Category: Cat Care

Diagnosing Pandora Syndrome in Cats

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Some of the Signs that May Indicate Pandora Syndrome

The term “Pandora syndrome” was coined by Tony Buffington of Ohio State University to describe cats with chronic clinical symptoms suffering from health issues involving multiple organ systems. Buffington initially studied a group of 200 cats that had “incurable” urinary tract symptoms (bloody urine, difficulty urinating, urinating outside the box, and urinating small amounts). These cats had other health issues in addition to the urinary tract disease.  Curiously enough, the cats’ symptoms resolved after living in an enriched environment (Reference 1).

Early studies linked the urinary symptoms to diets containing too much magnesium, causing formation of urinary stones. However, dietary changes did not resolve the cats’ urinary issues and they continued to suffer from bloody urine, difficulty urinating, urinating outside the box, and urinating small amounts, frequently in the absence of stones (Reference 1).

diagnosing Pandora Syndrome in cats

What “Pandora Cats” have in common (Reference 2):

  • history of traumatic experiences such as abandonment, orphaning, infection
  • having more than one disease at once
  • clinical symptoms that wax and wane in response to changes in the environment

More About Pandora syndrome in cats

Genetic makeup and traumatic events are thought to contribute to Pandora syndrome in cats. Our genomes (cats and humans) contains the DNA that makes us unique. DNA is made up of 4 building blocks that can be assembled in different orders. The sequence of the DNA building blocks in a gene provides the code for a particular trait such as eye or hair color (Reference 3).

However, there is more to growth and development than just genes that code for a particular trait. The science of epigenetics studies modifications to our DNA that don’t change the order of the DNA building blocks. The epigenome refers to chemical compounds that are attached to your DNA. Exposure to pollutants, what you eat, and stress are some things that can result in certain molecules attaching to your DNA and turning particular genes on or off. This is why genetically identical twins may have different skills, health, or behavior (Reference 3).

The epigenome is reset when the genome is passed on from parents to their offspring at conception. Maternal stress during pregnancy, traumatic events such as abandonment, orphaning, and infection can subsequently affect the epigenome. While many cats recover from these things, others may develop chronic illnesses or behavioral abnormalities (Reference 2).

Pandora cats are inherently “sensitive” cats who have difficulty coping with challenges presented by their environment.  They have a heightened stress response that increases the likelihood of them becoming ill.

Why the name “Pandora” syndrome?
Pandora is a figure from Greek mythology. She was a human woman made by the gods from clay.  She was endowed with many attributes, such as beauty, charm, cleverness, and curiosity. Before sending her to earth, the gods gave her a box, that she was told NEVER to open. Pandora’s curiosity got the best of her one day and she opened the box, releasing evils to plague mankind – disease, violence, greed, old age, death… However, all was not lost. Hope was also in the box to help people survive and cope with the evils in the world.

Like Pandora’s box, “Pandora cats” have multiple problems (“evils”).

diagnosing pandora syndrome in cats

A diagnosis of Pandora Syndrome is a diagnosis of exclusion – the symptoms may respond to medical therapies but then recur. Diagnostic procedures do not reveal a root cause. Diagnosis requires an extensive review of the cat’s life history, medical history and home environment. Some sample questions are below. (A more complete history form can be found in the supplementary materials of Reference 2).

Life History

  • where did the cat come from? from a shelter? was he/she a stray? an orphan?
  • are other cats/pets in the house?
  • how many people in the house?
  • indoor only? outdoor access?
  • is your cat fearful? friendly?

Medical History

  • vomiting? diarrhea? coughing? sneezing?
  • using litter box?
  • history of medical problems- e.g. allergies, heart problems?

Environmental Resources

  • safe and secure resting places?
  • multiple, separated litter boxes, feeding stations, water bowls?
  • can the cat interact with people and other pets on his/her own terms?

treating pandora syndrome in cats

Pandora syndrome is treated with medical therapies and MEMO (multimodal environmental modification).   MEMO aims to reduce the cat’s perception of threat and increase his/her perception of control of his/her environment. There is no cure for Pandora syndrome but medical therapies and MEMO can reduce the cat’s clinical signs and increase the time between episodes of symptoms (Reference 1).

The goal of MEMO is to create an OPTIMAL environment for the individual cat.  This will be the subject of the next post.

references

  1. C.A. Buffington DVM, PhD, DACVN.  Pandora Syndrome in Cats: Diagnosis and Treatment; Today’s Veterinary Practice. August 10, 2018, Issue: September/October 2018. viewed on 1/06/24 https://todaysveterinarypractice.com/urology-renal-medicine/pandora-syndrome-in-cats/
  2. Tony Buffington CA, Westropp JL, Chew DJ. From FUS to Pandora syndrome: Where are we, how did we get here, and where to now? Journal of Feline Medicine and Surgery. 2014;16(5):385-394. doi:10.1177/1098612X14530212
  3. National Human Genome Research Institute; Epigenomics fact sheet 8/16/20. Viewed on 1/6/24. https://www.genome.gov/about-genomics/fact-sheets/Epigenomics-Fact-Sheet.

 

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Managing the Diabetic Cat – Home Monitoring and Emergencies

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A diabetic cat sports a fabric collar over her glucose sensor.

Managing the diabetic cat

Managing the diabetic cat is a balancing act.  The goal is to reduce the clinical signs of diabetes while avoiding complications like low blood sugar.

How do you know if the therapy your veterinarian has chosen for your cat is working?  Monitoring the clinical signs of diabetes is a start. (Reference 1).  Pay attention to:

  • Your cat’s attitude and activity level
  • daily thirst and urination
  • daily food intake
  • weekly weight and body condition score

 Your veterinarian will want to monitor your cat’s blood and urine regularly but these are “snapshots” (values at a particular time on a particular day). What is happening during a diabetic cat’s day?

monitoring Insulin-based therapies

Insulin-based diabetic therapies focus on the level of glucose in the blood.

  • Blood sugar is highest before giving one of the twice daily injections of insulin.
  • After giving insulin, the cells start to take up glucose and the level of glucose in the blood starts to drop
  • Blood sugar levels out somewhere between the morning and evening doses and starts to increase as insulin wears off
  • The lowest point in the plot is called the “nadir”; the high points in the morning and evening are called “peaks”

If you sample your diabetic cat’s blood every few hours and plot the blood glucose values on a graph, you will get a picture of how the insulin is working.

 

 

The Home Glucose Curve

Because cats are prone to stress hyperglycemia, it is best to measure these curves at home. This can be done using (1) a handheld meter and sampling every few hours or (2) a Continuous Glucose Monitoring system, consisting of an electronic sensor applied to the cat and a device to read the output of the sensor.

Blood Glucose Meter

These are like the meters used by human diabetics. Instead of pricking a fingertip, it is typical to prick the area around the vein that runs along the outside of the ear. The strip in the glucose meter soaks up the blood like a sponge and a current is generated. The strength of the signal is proportional to the blood sugar.

Continuous Glucose Monitoring System

A Freestyle sensor on the back of a cat’s neck

The Freestyle Libre is a continuous glucose monitoring system developed for humans that can be used with cats. The electronic sensor is the size of two stacked US quarters; the sensor can be scanned with a smartphone or dedicated reader device. The sensor samples every minute and stores data for 8 hours before starting to overwrite it.  It is important to scan the sensor at least every 8 hours.

Sensor life can range from a few days to 2 weeks. The sensor can be placed on the back of the neck, behind the shoulder, or on the flank. A 2″ x 2″ area is clipped and cleaned for sensor application.

A plot of the average of glucose reading recorded during a two week period.

Monitoring glucose allows your veterinarian to adjust the insulin dose or change the type of insulin to best regulate your cat. The goals of insulin therapy are (Reference 1):

  • Peak Glucose values of 180-250 mg/dL
  • Nadir Glucose values of 80-144 mg/dL

managing the diabetic cat – emergencies

HYPOGLYCEMIA
Low blood sugar can be life threatening when blood glucose drops to < 40 mg/dL.  You may notice your cat is tired, unresponsive, disoriented and anxious.

What triggers hypoglycemia in the managed feline diabetic?

  • insulin dose is too high relative to food intake
  • too much insulin is given
  • your cat is in remission

If your cat’s glucose in the blood is normal, there is no glucose in the urine, and his fructosamine is in normal range, your veterinarian will start to gradually reduce the insulin dose until insulin is discontinued.  If blood glucose values remain in the normal range and there is no glucose in the urine for 2- 4 weeks once insulin has been stopped, your cat is in remission!

If you suspect low blood sugar…

  1. measure blood glucose (BG)
  2. BG less than 80 mg/dL – feed the cat or give up to 1 tablespoon corn syrup by mouth (1 tbsp = 15 mls – you don’t need to give this all at once)
  3. recheck BG in 15 minutes
  4. if glucose rises, continue to offer food and check glucose until the value is in a normal range
  5. notify your veterinarian
  6. if your cat is unconscious, rub some syrup on his gums or inside his cheek, measure BG, and go the the ER!

DIABETIC KETOACIDOSIS

Diabetic cats have an abnormal glucose metabolism and their bodies may break down fats for energy, resulting in ketones in the bloodstream. Too high a level of ketones makes the blood acidic, causing cells to function abnormally. This is more likely to happen:

  • in newly diagnosed diabetics and poorly regulated diabetics
  • when there are illnesses such as infections, tumors, dental disease (Reference 2)

Watch for…

  • Loss of appetite
  • Lethargy and depression
  • Vomiting/diarrhea
  • dehydration
  • difficulty breathing
  • a sweet smell to the cat’s breath

This is a true emergency – high levels of ketones in the blood and urine combined with the blood and other body fluids becoming acidic can be fatal. Treatment starts with IV fluids to correct dehydration and electrolyte imbalances and administration of insulin to restore glucose as the main source of energy.

Managing the diabetic cat: non-insulin based therapies

Blood glucose curves are part of the recommended monitoring process for cats receiving oral non-insulin therapy but they do not have as important a role as monitoring a cat on insulin.  Cats receiving the oral therapies are not prone to low blood sugar and the blood glucose curve will not have the characteristic shape of a cat receiving insulin. Glucose readings are simply averaged.  It is more important to monitor ketones as these cats may be more prone to develop DKA.

Ketones can be monitored using “urine dipsticks”.  The cat’s urine is collected using non-absorbent litter or a litter tray with a sieve bottom. Urine is collected with a syringe and dropped on the urine test strip (Reference 1).  The makers of Senvelgo, a oral liquid non-insulin drug, recommend checking ketones this way every 1-3 days in the first 14 days of therapy.

Urine dipsticks detect acetoacetic acid and are not very sensitive. Hand-held meters that detect levels of beta-hydroxybutyrate in the blood provide a more sensitive measure of ketones.  Blood can be collected from the ear vein of the cat and level of ketones measured similar to the blood glucose meters described above.  Abott’s Precision Xtra meter has been validated for use in cats (Reference 3).  Perhaps, as  non-insulin therapies become more common, monitoring of ketones in the blood will become part of managing the diabetic cat at home.

With appropriate treatment, the diabetic cat can have a life expectancy similar to cats without diabetes. The key to managing the diabetic cat is early diagnosis, weight control, regular exams and labwork, and home monitoring of clinical signs, glucose and ketones.

references

  1. ISFM Consensus Guidelines on the Practical Management of Diabetes Mellitus in Cats. Sparkes, A. (chairman), Journal of Feline Medicine and Surgery (2015) 17, 235-250
  2. Rudloff E. Diabetic ketoacidosis in the cat: Recognition and essential treatment. Journal of Feline Medicine and Surgery. 2017;19(11):1167-1174. doi:10.1177/1098612X17735762
  3. Weingart C, Lotz F, Kohn B. Validation of a portable hand-held whole-blood ketone meter for use in cats. Vet Clin Pathol. 2012 Mar;41(1):114-8. doi: 10.1111/j.1939-165X.2011.00389.x. Epub 2012 Jan 17. PMID: 22250845.

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Treating Diabetes in Cats – Insulin and Non-Insulin Therapies

Posted on by felinepurrspective_u3q4o6
Insulin injections can be given under the skin in the loose skin over the shoulders.

Diabetes is a condition where there is persistently high levels of glucose in the blood and urine. In healthy cats, insulin, a hormone produced by the beta cells in the pancreas, signals the cells in the body to take up glucose, reducing the glucose in the blood and urine. Diabetic cats are similar to human Type 2 diabetics –  they are insulin resistant and have beta cells that are not functioning normally. What treatments are available for these cats?

treating diabetes in cats

One way to treat diabetes in cats is to supplement the insulin the cat is still producing with twice daily injections of insulin. There is not a commercially available feline insulin.  Fortunately, production of anti-insulin antibodies does not appear to be a significant problem in cats and we can turn to the synthetic insulins made for the human market or a product derived from pig insulin, developed for dogs (Reference 1).

Practitioners typically reach for the longer-acting insulins listed below to manage feline diabetics (Reference 1)

  • Glargine (brands:Lantus, Basaglar) is given twice daily. It is available in a 100 Units (U)/ml solution. It does not need to mixed before use and should be clear, not cloudy.
  • Protamine Zinc Insulin (PZI) is also given twice daily. It comes in a 40 Units (U)/ml suspension which should be rolled or inverted gently to suspend it before using.

Vetsulin is derived from porcine insulin and has a shorter duration of action compared to glargine and PZI. It is not as well tolerated by cats as glargine and PZI. It should be shaken prior to use and be uniformly white in color. It is available in a 40 Units U/ml suspension.

treating diabetes in cats with insulin

Insulin is given by syringe under the skin (subcutaneously) every 12 hours. It is best to stick to the every 12 hour schedule but if this is not possible, you can administer it within 2 hours before or 2 hours after the 12 hour mark. Skip the dose if you are out of this window (Reference 1).

Insulin Syringes

  • U-100 syringes are used with Glargine insulin.
  • U-40 syringes are used with PZI and Vetsulin.
  • Syringes with 0.5” needles are recommended – shorter needles may not always go far enough through the skin.

Giving Insulin Injections

  • The injection can be given in the loose skin near the shoulder blade or hip.
  • Rotate injection sites to avoid build up of scar tissue and for better absorption of the drug.
  • There are many good videos on giving subcutaneous injections.  Take a look at the “Caring for your Diabetic Cat” video on the “Health Topics” page at Cornell Feline Health Center.
Insulin can be given in the loose skin over the shoulders and hips.

 

Try to make giving injections as pleasant as possible. Establish a routine. It can help to have dedicated place to give treatments, for example, a soft blanket on one side of the sofa. If there is a treat or food your cat likes, be sure to offer this during or after the injection.

 

 

Diet and the Diabetic Cat

Insulin resistance has been linked to obesity in cats. If your diabetic cat is obese, losing weight can help manage his diabetes and possibly reduce his insulin dose.

If your cat has lost weight due to diabetes, start insulin therapy before starting a weight loss program. Once your cat is stable and you have established your “diabetic” routine, implement your weight loss plan (Reference 2).

Plan for weight loss

  1. determine how many calories your cat is eating
  2. reduce current calories by 10-20%
  3. monitor weight and body condition score (BCS)

Diets for Diabetic Cats

  • a high protein, low carbohydrate diet is recommended
  • canned foods are recommended due to their higher water content and lower carbohydrate content
  • many obese cats have low BCS in spite of excess body fat and high protein may be needed to maintain lean body mass

There are therapeutic diets targeted at treating diabetes in cats.  Purina DM and Hill’s m/d  feature high protein and low carbohydrates. If your cat does not care for high protein/low carb diets, consider a high protein, low fat, moderate fiber and moderate carbohydrate diet such as Hill’s w/d food, designed to address glucose balance as well as weight loss and urinary care.

For cats with concurrent diseases, you will have to choose which condition is better treated by diet.  For example, if your cat has kidney disease and diabetes, it may be wise to feed a kidney diet and manage the diabetes by adjusting insulin dose or type of insulin. 

treating diabetes in cats – “non-insulin” therapies

Recently, the FDA approved two drugs given orally for diabetic cats: Bexacat (12/2022) and Senvelgo (8/2023). Bexacat is a  once daily tablet; Senvelgo is a liquid given once daily with food or directly into the cat’s mouth.

Both these drugs (SGLT2 inhibitors) work by blocking the reabsorption of glucose by the kidneys. Instead of being returned to the bloodstream, glucose is excreted in the urine, lowering blood sugar without insulin.  High levels of blood glucose have been tied to beta cell dysfunction – SGLT2 inhibitors lower blood sugar and are thought to promote growth of new beta cells (Reference 3).

These drugs work best for treating diabetes in cats who have been recently diagnosed and have NOT had previous insulin treatment. At this time, Bexacat and Senvelgo are NOT recommended for cats…(Reference 4)

  • 13 years or older
  • with pancreatitis or a history of pancreatitis
  • with kidney disease or other concurrent disease
  • having suffered a condition known as ketoacidosis.

Candidates should be healthy, with the exception of being diabetic (Reference 4).

Treating diabetes in cats has traditionally focused on giving insulin injections and feeding a high protein, low carbohydrate diet. Experts recommend using the long-acting insulins for cats.  The injections are given twice daily.  Recently, new oral  therapies have been made available that offer once-a-day dosing and the potential of regenerating pancreatic cells.

In the next post, we will look at how we can monitor insulin and non-insulin therapies to ensure our diabetic cats’ health and safety.

references

  1. ISFM Consensus Guidelines on the Practical Management of Diabetes Mellitus in Cats. Sparkes, A. (chairman), Journal of Feline Medicine and Surgery (2015) 17, 235-250
  2. Clark M, Hoenig M. Feline comorbidities: Pathophysiology and management of the obese diabetic cat. Journal of Feline Medicine and Surgery. 2021;23(7):639-648. doi:10.1177/1098612X211021540
  3. (Nakamura A. Effects of Sodium-Glucose Co-Transporter-2 Inhibitors on Pancreatic β-Cell Mass and Function. International Journal of Molecular Sciences. 2022; 23(9):5104. https://doi.org/10.3390/ijms23095104 )
  4. AAHA publications NEWStat® 2023-1 New oral diabetes medication for cats requires careful case selection  Singler, Emily  1/13/23. https://www.aaha.org/publications/newstat/articles/2023-1/new-oral-diabetes-medication-for-cats-requires-careful-case-selection/ viewed 11/23.

 

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Diabetes in Cats – What is it? How is it diagnosed?

Posted on by felinepurrspective_u3q4o6
This diabetic cat is walking on his ankles. This is called a plantigrade stance.

Diabetes is a condition where there is persistent high glucose (sugar) in the blood and the urine. Like humans, cat can develop diabetes.  Which cats are at risk for diabetes? How do you diagnose diabetes in a cat?

Two previous posts addressed diseases that we tend to see in older cats, chronic kidney disease and hyperthyroidism. This post completes the trio by looking at feline diabetes.

diabetes in cats

Why do high levels of glucose occur in the blood and urine? Uptake of glucose by the muscle and fat cells in the body is dependent upon the hormone insulin. Insulin, produced by the “beta” cells in the pancreas, signals these cells to take up glucose. If the beta cells fail to produce enough insulin, these cells will not receive glucose, and, consequently, will not have energy for cellular functions. The glucose  in the blood stream is then filtered out into the urine. 

clinical signs of diabetes

Clinical signs of diabetes (Reference 1) are similar to those of hyperthyroidism and chronic kidney disease.

  • increased thirst and urination
  • weight loss
  • increased appetite

In some cases of uncontrolled diabetes, a cat will start walking on his ankles, referred to as a “plantigrade stance”. Cats often recover a normal gait after several months of treatment for diabetes. Some practitioners use oral methylcobalamin, a form of vitamin B12, to help speed up recovery (Reference 2).

 

the feline diabetic

Most feline diabetics are similar to type 2 human diabetics: they have insulin resistance and beta cells that are not functioning normally.

  • when muscle and fat cells become resistant to insulin, more insulin is needed to maintain glucose uptake.
  • beta cells in the pancreas respond by producing more insulin.
  • high levels of insulin trigger the liver to store glucose as glycogen instead of releasing it into the bloodstream (the cat is still able to get glucose from the GI tract).
  • eventually, the beta cells cannot continue “hyper-secreting” insulin and fail, resulting in high levels of glucose in the blood, not in the cells. (Reference 3)

diabetes in cats – who is at risk?

  • obese cats
  • cats over 7 years old
  • cats that are not very active
  • male and neutered cats
  • cats receiving steroids such as prednisolone

Obese cats are 2-4 times more likely to develop diabetes mellitus. Obesity leads to insulin resistance in the muscle and fat cells. However, many overweight cats never develop diabetes. They will have normal blood glucose values as long as the beta cells can produce enough insulin to suppress glucose production in the liver.

diagnosing diabetes in cats

Persistent high glucose levels in the blood (hyperglycemia) and urine (glycosuria) accompanied by one or more of the clinical signs above support a diagnosis of diabetes mellitus. A thorough history needs to be taken and a complete physical examination done.  Diagnostic blood work will include routine chemistries, a complete blood count, urinalysis, urine culture or bacterial assay, and T4 measurement.

Why measure T4?
Excess thyroid hormone increases glucose production in the liver. If a cat is hyperthyroid, the hyperthyroidism needs to be managed in order to control the blood sugar.

One of the challenges to diagnosing diabetes in cats in the veterinary clinic is stress hyperglycemia. A cat’s blood glucose values can become falsely elevated due to the stress of the car ride, the exam and other factors. If the blood glucose is high enough, glucose spills over in the urine, also causing a false positive. Options to rule out stress hyperglycemia include (Reference 4):

  • repeating the lab work on a subsequent visit with the patient on pre-visit sedation
  • collecting a urine sample at home
  • measuring blood glucose at home
  • adding a serum fructosamine to the blood panel

Fructosamine measures the average of the blood glucose over the two weeks preceding the sample collection and consequently should not be affected by stress hyperglycemia. Fructosamine may not be accurate if the cat became diabetic within the past two weeks or if the cat has uncontrolled hyperthyroidism (Reference 1)

Once your cat is diagnosed with diabetes, what happens next?

The next post will address the treatments available to the diabetic cat and how the chosen therapy must be monitored.

references

  1. Sparkes, A (chairman), ISFM Consensus Guidelines on the Practical Management of Diabetes Mellitus in Cats, Journal of Feline Medicine and Surgery (2015) 17, 235-250
  2.  Sereno, R. Managing complications in diabetic cats, DVM 360:article 5/1/2011. https://www.dvm360.com/view/managing-complications-diabetic-cats (viewed 11/2023)
  3. Clark M, Hoenig M. Feline comorbidities: Pathophysiology and management of the obese diabetic cat. Journal of Feline Medicine and Surgery. 2021;23(7):639-648. doi:10.1177/1098612X211021540
  4. American Association of Feline Practitioners, Diabetes Educational Toolkit, https://catvets.com/diabetes-toolkit/troubleshooting, viewed 11/2023

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Diets for Managing CKD in Cats

Posted on by felinepurrspective_u3q4o6

canned cat food meal feeding

Diet is a key therapy for cats with chronic kidney disease (CKD). Diets for managing CKD in cats aim to (Reference 1):

  • lessen the clinical signs of CKD
  • slow the progression of the disease
  • provide adequate nutrition

Diets for managing ckd in cats

The goal of diets for managing CKD in cats is to reduce the amount of uremic waste products while providing adequate nutrition. There are a number of commercially available diets that are formulated to do this. These foods feature (Reference 1):

  • reduced phosphorus
  • restricted amounts of high-quality protein
  • higher calories
  • reduced sodium
  • potassium supplementation
  • B vitamins and fatty acids

Phosphorus

Phosphorus is needed for the growth, maintenance, and repair of all tissues and cells, and for the production of the genetic building blocks, DNA and RNA. Phosphorus is also needed to help balance and use other vitamins and minerals, including vitamin D, iodine, magnesium, and zinc (Reference 2).

As kidney disease progresses, the ability of the kidneys to excrete phosphorus declines. To reduce stress on the kidneys, diets for managing CKD in cats aim to reduce the amount of phosphorus and balance the ratio of calcium to phosphorus. Too much phosphorus and not enough calcium can lead to kidney and bone damage (Reference 1). Commercial kidney diets are formulated to maintain an appropriate ratio of calcium to phosphorus.

protein in diets for managing cats with ckd

Since protein contributes significantly to phosphorus content, kidney diets restrict the amount of protein. Less protein means less uremic waste products. Emphasis is placed on formulating these diets with “high quality” protein. High quality proteins are a “complete package” and provide the cat with all the amino acids he or she needs. Thus, the protein used is highly bioavailable and generates less uremic waste products (Reference 1).

There are concerns that reduced protein diets predispose cats to weight loss and loss of lean muscle mass. Some recent studies suggest that senior cats may require more protein than younger cats to maintain lean body mass (LBM) (Reference 1).

Some practitioners advocate feeding higher protein diets to cats suffering with CKD to maintain the LBM. This may not be the answer to maintain LBM – increased protein in the cat’s diet means more uremic waste, making the cat feel nauseated and not inclined to eat. Ultimately, the cat will be eating less and calorie reduction will lead to muscle wasting as the cat’s body uses his own muscles for nutrition (Reference 3).

More on Lean Body Mass…

A recent study in 2019 (Reference 4) found a correlation between consumption of essential amino acids (essential amino acids must be consumed in the diet) and LBM. Cats with CKD Stages 1 and 2 were fed either a control kidney diet or a higher calorie “test” kidney diet that included higher amounts of essential amino acids and carnitine, an amino acid derivative that plays a role in energy production in the body.

The cats eating the lower calorie control diet lost LBM whereas the other group of cats eating the “test” diet maintained their LBM. Researchers observed that the cats on the control diet did not eat enough food to get adequate amounts of essential amino acids.  They found that essential amino acid intake, not total dietary protein, correlated with maintaining LBM.  

Although offering reduced protein, most commercial kidney diets make sure that more than sufficient amounts of the essential amino acids are available.  The challenge is to get cats with CKD to eat enough of the diets.

Other Supplements

Commercial diets for managing CKD in cats also supplement:

  • Potassium, an electrolyte essential to the function of muscles and nerves
  • B vitamins – these water soluble vitamins can be depleted as the cat drinks more water and urinates more
  • Fatty acids – fatty acids found in fish oils are thought to reduce inflammation and decrease protein in the urine

Starting a kidney Diet

Renal diets are typically recommended for cats in IRIS Stages 2, 3, and 4. Occasionally a reduced protein diet may be prescribed for a Stage 1 cat who has persistent protein in her urine. Many practitioners like to introduce therapeutic diets when the cat is in IRIS Stage 2, because the cat should still be feeling well and more likely to accept the new diet (Reference 3).

The best time to switch to a kidney diet is when your cat is eating her regular cat food well and is feeling well. Wait to introduce the new diet if…

  • Your cat has just come back from the hospital
  • You have visitors or are doing home remodeling
  • Your cat is not eating her regular food well
  • Your cat is vomiting or having diarrhea

Introduce the new diet gradually, over several weeks (Reference 1)

       

Week 1

Week 2

Week 3

Week 4

Offer 25% of the new diet and 75% of the current food

Offer 50% of the new diet and 50% of the current food

Offer 75% of new diet and 25% of the current food

Offer 100% of the new diet

Make sure to offer the appropriate amount of calories to your cat – the new renal diet will most likely be more caloric than the your cat’s current food and you will not need to feed as much.

tips for transitioning to a kidney diet

  • Choose a food similar to the one your cat is eating already – wet or dry? fish or chicken?
  • Offer the new food in a separate bowl alongside the regular food
  • Make sure to offer fresh food
  • Use a “topper” to encourage your cat to try the new food – fish flakes or a favorite treat
  • Try gently warming wet foods – the stronger smell may make the food more appealing
  • Meal feed your cat – small, frequent meals gives your cat more chances to try the new food
  • Avoid mixing medications into the new food – use a small amount of another food or pureed treat to give the medications

from “Helping Your Cat Transition to a Therapeutic Kidney Food”, Hill’s Pet Nutrition/Clinician’s Brief, Educational Concepts, LLC © 2022

If you are struggling with a finicky cat, talk to your vet. If your cat is healthy, ask if you can do a trial of mirataz to stimulate his appetite and facilitate the transition to the new food.

Alternatives to a commercial kidney diet

  • Use a phosphorus binder in the food your cat will eat. Consult your veterinarian for the appropriate dose.
  • Home cooked diets are an option but should be formulated by a veterinary nutritionist.  Nutritionists affiliated with websites such as balance.it  will work with your vet to formulate a recipe for your cat.

Studies have shown that diets for managing CKD in cats can increase longevity, help control uremia and maintain phosphorus concentrations. While some have concerns about the protein restriction in these diets, kidney diets have been shown to maintain LBM providing the cat eats enough food to get sufficient nutrition.

New research is focusing on the connection between the kidneys and the GI tract, particularly the uremic toxins that originate in the gut. Prebiotic and probiotic treatments in CKD cats are being investigated to see if improving the health of the microorganisms living in the gut can reduce blood concentrations of gut-derived uremic toxins. (Reference 5)

references

  1. Quimby, J. and Ross, S., Diets for Cats with Chronic Kidney Disease (CKD) [updated 2022]. http://www.iris-kidney.com/education/protein_restriction_feline_ckd.html [viewed 9/2023]
  2. Phosphorus: Fact Sheet for Health Professionals, https://ods.od.nih.gov/factsheets/Phosphorus-HealthProfessional/, viewed 9/2023.
  3. Cave, N. and Wall, M. Protein restriction for cats with chronic kidney disease, Vet Focus, Issue # 30.1, © 6/25/20
  4. Hall JA, Fritsch DA, Jewell DE, Burris PA, Gross KL. Cats with IRIS stage 1 and 2 chronic kidney disease maintain body weight and lean muscle mass when fed food having increased caloric density, and enhanced concentrations of carnitine and essential amino acids. Vet Rec. 2019 Feb 9;184(6):190. doi: 10.1136/vr.104865. Epub 2018 Dec 4. PMID: 30514741; PMCID: PMC6589452.
  5. Summers, S. and Quimby, J., The feline gut-kidney axis: food for thought, Veterinary Focus, Issue #33.1, 5/31/23, https://vetfocus.royalcanin.com/en/scientific/the-feline-gut-kidney-axis-food-for-thought, viewed 9/2023

Managing the Cat with Chronic Kidney Disease

Posted on by felinepurrspective_u3q4o6
HDO BP cat
A cat relaxes in his basket during a home blood pressure check. Regular blood pressure checks are essential to monitoring chronic kidney disease.

Chronic Kidney Disease (CKD) in cats is progressive and not curable but there are strategies we can undertake to improve the quality of life of our “kidney” cats and possibly give them some more time with us. Here is a checklist for managing the cat with chronic kidney disease:

  1. Keep Kitty hydrated
  2. Feed a diet that will lessen the stress on the kidneys
  3. Maintain appetite
  4. Manage high blood pressure
  5. Treat anemia if necessary
  6. Treat urinary tract infections

Managing the cat with chronic kidney disease

hydration

Kidney failure is tied to the “death” of nephrons that filter the blood. The remaining nephrons compensate by increasing filtration. Dehydration decreases renal blood flow putting more stress on the remaining nephrons. Keeping the “kidney” cat hydrated helps maintain electrolyte concentrations and dilute the waste products the kidneys are struggling to filter out.

Increasing Voluntary Water Intake

  • Have a variety of water sources and fountains in the home to encourage water intake.
  • Consider feeding a wet diet – many canned foods contain about 80% water.
  • Try water from tuna, water used to poach chicken or fish (offer alone, add to the water bowl, or try frozen in an ice cube tray and added to the water bowl). 

Hydration supplements like Purina’s Hydra Care are designed to maximize the amount of water cats take in while drinking. Nutrient enriched water is more viscous, clings to the cat’s barbed tongue, and increases the water consumed with each lap of the tongue.

Subcutaneous Fluids

This refers to giving fluids under the skin, not in a vein. It is done using a bag of sterile fluids, an IV line and a needle. This is a strategy often employed in IRIS stages 3 and 4 of kidney disease.  This can be done in the veterinary clinic or at home, once you and your cat are comfortable with the process.

Kidney-friendly diets

As the kidneys fail, they are no longer as efficient at filtering the waste products of protein metabolism. Phosphorus in the form of phosphates tends to build up in the body while potassium levels may drop.

Commercial renal diets for kidney cats feature reduced phosphorus and restricted amounts of high-quality protein, an increased calorie density, sodium restriction, potassium supplementation, supplementation with B vitamins, anti oxidants and omega-3 fatty acids (Reference 1). There have been a number of studies done addressing the effectiveness of these diets – the results show that cats suffering from CKD lived longer when fed a renal diet (Reference 2).

Phosphorus Binders

For some cats in advanced stages of CKD, a renal diet may not reduce phosphorus enough; other cats simply refuse to consume a renal diet. For these cats, adding a “binding agent” to the food can help reduce the amount of phosphorus that is available for the cat to metabolize. Supplements that “bind” with the phosphates in the food form a nonabsorbable compound eliminated in the stool.   “Phosphorus binders” include (Reference 1):

  • Aluminum hydroxide
  • Calcium carbonate
  • Calcium acetate
  • Sevalamer (a hydrogel of poly-allylamine, free of aluminum and calcium)

 appetite and nausea

A “kidney” cat can suffer from nausea and vomiting due to the buildup of uremic toxins in the bloodstream. The cat consequently doesn’t eat well resulting in dehydration and weight loss. Reduced potassium levels and anemia due to CKD also contribute to a reduced appetite (Reference 1).

Medical Management

Managing the cat with chronic kidney disease also includes managing nausea and vomiting. Drugs that target nausea and vomiting include maropitant (Cerenia) and ondansetron. These are typically available in oral tablets.

There is another drug that is often the first choice of many practitioners. Mirtazapine is an antidepressant drug that not only controls nausea and vomiting, it also stimulates appetite.

  • available in a transdermal gel (Mirataz) as well as tablets
  • the transdermal form is FDA approved for use in cats
  • the transdermal gel is applied once daily and the dose is easily adjusted
  • side effects are vocalizing and increased activity.

If a cat is too nauseous or unwell to maintain food intake, a feeding tube should be considered.

high blood pressure

Increased filtration rate in the remaining nephrons and activation of the renin-angiotensin system can lead to high blood pressure in cats with CKD. Systolic blood pressures over 160 mm Hg require treatment to prevent damage to the cat’s eyes, heart and kidneys. In particular, the leakage of proteins into the urine (proteinuria) can be reduced once high blood pressure is managed (Reference 1).

Amlodipine is the most commonly used drug to reduce cats’ blood pressure. It is a calcium channel blocker that is available in tablets that can be taken once or twice daily. Amlodipine typically reaches therapeutic levels in 7-10 days.  Managing the cat with chronic kidney disease should include a blood pressure check every 3-6 months.

anemia

One of the kidney’s functions is to produce the hormone erythropoietin. Erythropoietin triggers cells in the bone marrow to make more red blood cells. Failing kidneys may not generate enough erythropoietin and anemia (low levels of red blood cells) can result.

Fewer red blood cells means less hemoglobin. Less hemoglobin means less oxygen is getting moved around the body. Anemia can result in weakness and tiredness. 

If the fraction of red blood cells in the blood drops below 20%, many practitioners will supplement the cat with a man-made analog of erythropoietin. The most commonly used drug is darbepoetin; it is given as an injection under the skin. Injections of iron supplements often accompany the darbepoetin injections in the initial stages of therapy (Reference 1).

A new treatment (2023) is available for anemia in cats with CKD.  Varenzin -CA1 is a once daily oral liquid medication made specifically for cats.  Varenzin-CA1 is designed to stimulate the cat’s body to make its own erythropoetin.

Urinary tract infections (UTI)

With increasingly dilute urine seen in cats with CKD, UTI’s are more common. Most of these UTI’s do not have clinical signs such as frequent urination or blood in the urine. Urinalysis should be part of the CKD cat’s checkup. White blood cells found in a centrifuged urine sample are indications for a bacterial culture and treatment. Treatment can be based on sensitivity testing and a kidney friendly antibiotic chosen.

Managing the cat with chronic kidney disease requires attention to multiple factors. Treating dehydration, nausea, high blood pressure and anemia can keep the “kidney” cat comfortable and slow the progression of the disease. A critical part of managing the cat with chronic kidney disease is feeding an appropriate diet. The next post will look at the science behind the commercial renal diets and alternatives to them.

references

  1. Sparkes, A. (panel chair), ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease, Journal of Feline Medicine and Surgery (2016) 18, 219–239.
  2. Quimby, J. and Ross, S., Diets for Cats with Chronic Kidney Disease (CKD) [updated 2022]. http://www.iris-kidney.com/education/protein_restriction_feline_ckd.html [viewed 9/2023]

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Chronic Kidney Disease in Cats

Posted on by felinepurrspective_u3q4o6
Cat on Baby Scale
Weight loss is a symptom of kidney disease.

 

Chronic kidney disease (CKD) is common in older cats. A 2014 study found that 30-40% of cats over age 10 years had CKD. (Reference 1).

chronic kidney disease in cats

Let’s take a closer look at what the kidneys do for our cats.

  • regulate fluid volume in the body
  • maintain the pH and electrolyte composition of the body.
  • make renin, an enzyme that helps maintain blood pressure
  • make erythropoietin, a hormone that stimulates production of red blood cells
  • filter the blood removing waste products

Nephrons are the tubular structures in the kidney that filter the blood and produce urine. A cat’s kidney has about 200,000 nephrons (Reference 2).

Over time, nephrons become damaged and are replaced by scar tissue. Renal failure occurs when less than 25% of the nephrons are functional and the remaining nephrons can’t maintain adequate function. The most common cause is an inflammatory process called tubulointerstital nephritis (Reference 3).

The remaining nephrons compensate by increasing filtration rate. The result of this “hyper filtration” is scarring of the tubes in the nephrons and loss of protein into the urine. The “hyperactive” nephrons also release the enzyme renin. Renin triggers the production of the hormone, angiotensin II, that makes heart beat more forcefully and raises the cat’s blood pressure. (Reference 3).

Diagnosing Chronic Kidney Disease in Cats

Clinical Signs of Chronic Kidney Disease

Some clinical signs are similar to those of other chronic diseases such as hyperthyroidism and diabetes.  Like those disorders, these signs are usually not present until later in the disease process.

  • weight loss
  • increased thirst and urination
  • rapid pulse and breathing
  • unkempt hair coat

In addition the “kidney cat” may have

  • lethargy
  • weakness
  • poor appetite
  • bad breath or ulcers in the mouth (occasionally)

Diagnosing Chronic Kidney Disease in Cats

CKD is typically diagnosed by measuring creatinine and SDMA in the blood and measuring the urine concentration (Reference 1).

Creatinine

Creatinine is a by-product of energy-producing processes in the muscles. A healthy cat’s kidneys filter out most of the creatinine.  As kidney disease progresses, the remaining nephrons filter out less creatinine and values of creatinine in the blood rise.

SDMA

SDMA (symmetric dimethylarginine) is a metabolite of arginine, one of the essential amino acids for cats. SDMA is produced from metabolism of proteins and, like creatinine, is filtered out by the kidneys. Unlike creatinine, SDMA is not influenced by the change in muscle mass. SDMA is more sensitive to the increase in the filtration rate as kidney disease progresses. It will increase earlier than creatinine.

Urine Concentration

As remaining nephrons increase filtration to compensate for the loss of nephrons, the cat drinks more fluid and the urine he produces becomes more dilute.   As CKD progresses, urine concentration decreases.

the stages of chronic kidney disease

The International Renal Interest Society (IRIS) has formulated a guide to staging CKD in cats, as well as in other animals. There are 4 stages of CKD.  The table below summarizes the values for creatine and SDMA seen for cats in the stages of CKD.

Stage Creatinine (mg/dL) SDMA (mcg/dL) Comments
Stage 1 <1.6 <18   Blood values are normal but urine is dilute or kidneys are abnormal on examination or imaging
Stage 2 1.6 – 2.8 18 – 25 Clinical signs are mild or absent
Stage 3 2.9 – 5.0 26 – 38 Clinical signs are present but vary in severity
Stage 4 >5.0 >38 Risk of uremic crisis

 

Signs of Uremic crisis (end stage kidney failure):

Refusal to eat, vomiting, lethargy, confusion (possibly pacing and restlessness), withdrawn, uncontrolled urination or defecation, ammonia-like odor to the breath, seizures (from https://www.petmd.com/cat/conditions/urinary/kidney-failure-cats). Emergency treatment is needed.

other signs of chronic kidney disease in cats

Even if creatinine and SDMA are within normal limits, high blood pressure and protein in the urine may indicate that a cat has kidney disease.   Recall that as nephrons “die”, the remaining nephrons increase filtration to compensate and blood pressure rises. The higher pressure damages the walls of the tubes in the nephrons and protein can leak out into the urine.

High Blood Pressure

Systolic blood pressures under 140 mm Hg are considered normal; SBP 140- 159 is prehypertensive; over 160 is hypertensive and treatment is recommended. (see “Measuring Your Cat’s Blood Pressure: Why and How”)

Protein in the Urine

Protein in the urine can be associated with disease processes such as urinary tract infection.  Persistent protein in the urine warrants a closer look and the veterinarian will often choose to run a test to measure the urine protein creatinine ratio (UPCR). UPCR < 0.2 are normal; ratios of 0.2-0.4 are borderline; ratios over 0.4 support a diagnosis of CKD.

Diagnosis of chronic kidney disease can be challenging. Clinical signs are non specific and shared by other chronic diseases such as hyperthyroidism and diabetes. Because the kidneys have so much reserve capacity and our markers do not detect it until nephron death approaches 70-80%, it can be easy to miss some of the more subtle indicators of kidney dysfunction. It is important for our cats to have regular exams to assess their overall condition, lab work, and blood pressure measurement. Kidney disease is progressive and not curable, however, early intervention can slow down the process. In the next post, we discuss treatment of Stage 1 through Stage 4 of chronic kidney disease in cats.

references

  1. Sparkes, A. et al. ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease,  Journal of Feline Medicine and Surgery (2016) 18, 219–239, https://journals.sagepub.com/doi/pdf/10.1177/1098612×16631234
  2. Sadeghinezhad, J. and Nyegaard, J. Cat Kidney Glomeruli and Tubules Evaluated by Design-Based Stereology. The Anatomical Record, Volume 302, Issue 10, 18-46-1854, 14 May 2019, https://doi.org/10.1002/ar.24144
  3. Grauer, Gregory, Feline Chronic Kidney Disease, Today’s Veterinary Practice, February 6, 2015, Issue March/April 2015, https://todaysveterinarypractice.com/urology-renal-medicine/feline-chronic-kidney-disease/

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Diagnosing and Treating Hyperthyroidism in Cats

Posted on by felinepurrspective_u3q4o6

 

Over 10% of cats over 8 years old will be diagnosed with hyperthyroidism in their lives.  Although evidence points to thyroid disrupting chemicals in the cats’ food and environment, we don’t really know why these cats will become hyperthyroid.  Prompt diagnosis and treatment will help these cats live long and healthy lives.

Diagnosing and Treating Hyperthyroidism in Cats

Diagnosing

Clinical signs of hyperthyroidism include increased appetite and weight loss. These signs progress slowly and it may be months to years before the cat owner realizes that something is wrong.

Cats are considered seniors at the age of seven. Regular lab work is recommended for senior cats and most senior feline blood panels include a thyroid hormone (T4) measurement. Persistently elevated T4 concentrations coupled with one or more of the classic clinical signs (below) at the same time often confirms the diagnosis of hyperthyroidism. (Reference 1)

  • weight loss
  • increased thirst and urination
  • increased vocalization
  • hyperactivity
  • rapid pulse and breathing
  • vomiting, diarrhea
  • unkempt hair coat

This list of clinical signs is also shared with other feline diseases, such as diabetes, kidney disease, and GI disorders. These diseases can lower the T4 measurement, so that it is in the reference range, making diagnosis of hyperthyroidism challenging.

a challenging diagnosis

Cats that may have kidney disease as well as hyperthyroidism are particularly challenging to diagnose. Thyroid hormone increases the blood flow through the kidneys, often lowering kidney values to within the reference ranges. At the same time, kidney disease impairs the binding of T4 to proteins, reducing the T4 concentration. One disease masks the other and vice versa (Reference 2).

Cats with borderline T4 values and those suspected of having another chronic disease will need additional testing before a definitive diagnosis of hyperthyroidism is made. The veterinarian may request a more sensitive test called a “free T4 by equilibrium dialysis” in addition to remeasuring total T4. “Free T4” measures a form of T4 that is not bound to proteins in the blood. (Reference 3)

Routine thyroid monitoring in humans and dogs measures levels of  TSH or thyroid stimulating hormone. Unfortunately, levels of  TSH in hyperthyroid cats are often too low to be detected using canine tests. Zomedica has recently developed a feline TSH assay capable of measuring the low levels of TSH in cats which may aid in diagnosing feline hyperthyroidism. (Reference 3)

treating hyperthyroidism in cats

At the present time, there are 4 treatments available to cats with hyperthyroidism (Reference 1).

  • radioactive iodine (I-131)
  • medical management with a drug called methimazole
  • surgical removal of abnormal thyroid tissue
  • dietary therapy using iodine-restricted food

1. Radioactive Iodine (I-131)

Treating hyperthyroidism in cats with radiation must be done at a licensed facility. An injection of radioactive iodine is given under the skin, like a vaccine. The cat stays at the facility until radiation levels drop enough to send cat home (about 3-4 days) (Reference 1, 4)

  • 95% cure rate
  • side effects are rare
  • small risk of hypothyroidism (too much tissue is destroyed and the cat will need thyroid supplements)
  • owner must store wastes and soiled litter for 2 weeks
  • cannot cuddle kitty for extended times for 2 weeks post discharge (e.g. cat cannot sleep on bed)

2. Medical Management with Methimazole (Reference 1)

  • not a cure and the cat must receive daily medication to manage his hyperthyroidism
  • methimazole is available in pills and transdermal gel
  • frequent monitoring of T4 values is necessary
  • side effects: vomiting, facial itching, liver failure
  • tumor may continue to grow and become cancerous

3. Surgical Removal of Thyroid Gland (Reference 1)

The abnormal thyroid tissue is removed surgically, leaving the normal tissue alone. It is a procedure most surgeons can perform.

  • up to 90% cure rate
  • if not all the abnormal tissue is removed, hyperthyroidism can return
  • general anesthesia can be risky in cats with cardiac issues and kidney disease
  • there is a risk of damaging the adjacent parathyroid glands (regulate calcium in the body)
  • risk of hypothyroidism if too much normal tissue is removed

4. Dietary therapy (Reference 1)

Hills y/d diet reduces the amount of thyroid hormone in the body by decreasing the amount of iodine in the cat’s food.

  • response is 82% when on the diet
  • safe for cats with kidney disease
  • the cat cannot eat other foods
  • only low-iodine treats and water can be used
  • the cat will become hyperthyroid if he stops eating the diet

Both I-131 and thyroid surgery offer a cure for hyperthyroidism. However, both have a low risk of too much normal tissue being destroyed and the cat developing “hypothyroidism” as a consequence. The “hypothyroid” cat does not produce enough thyroid hormone and must be supplemented with daily oral medication for the rest of his/her life.

Both I-131 and surgery run the risk of unmasking more advanced kidney disease. Unlike medication or diet which can be adjusted or stopped, I-131 and surgery are permanent. Before recommending I-131 or surgery, some practitioners will conduct a trial with methimazole to assess kidney function when the hyperthyroidism is managed. However, some clinicians will opt to treat with I-131 even in the face of advanced kidney disease – persistent hyperthyroidism will further damage the kidneys if left untreated (Reference 5).

Diagnosing and treating hyperthyroidism in cats can be challenging. The presence of other diseases can mask hyperthyroidism and interfere with testing.  I-131 is considered the gold standard for treating hyperthyroidism in cats. It does not carry the risks of surgery, avoids the side effects of methimazole and the difficulties of maintaining a strict prescription diet with a cat. Whichever treatment you choose, you have taken a step toward giving your hyperthyroid cat a healthier and longer life.

 

references

  1. Carney HC, Ward CR, Bailey SJ, et al. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. Journal of Feline Medicine and Surgery. 2016;18(5):400-416. doi:10.1177/1098612X16643252
  2. Geddes R, Aguiar J. Feline Comorbidities: Balancing hyperthyroidism and concurrent chronic kidney disease. Journal of Feline Medicine and Surgery. 2022;24(7):641-650. doi:10.1177/1098612X221090390
  3. Kvitko-White, Heather. Recognizing and confirming feline hyperthyroidism. dvm360 March 2021 Volume 53, Feb 9, 2021. https://www.dvm360.com/view/recognizing-and-confirming-feline-hyperthyroidism (viewed 9/2023)
  4. Brooks, Wendy. Thyroid Treatment Using Radiotherapy for Cats. Veterinary Partner:VIN. Date Published: 01/01/2001
    Date Reviewed/Revised: 09/05/2023. https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951399 (viewed 9/2023)
  5. Vaughan, F. and Wackerbarth, D. “Methimazole Trials: What Are They Good For?”, https://www.felinehtc.com/documents/Methimazole-Trials.pdf (viewed 9/2023)

Hyperthyroidism in Cats – What is it? Why Does It Happen?

Posted on by felinepurrspective_u3q4o6
Thyroid Disruptors have a similar structure to the thyroid hormone T4

About 10% of senior cats will develop a condition called hyperthyroidism in their lives. Hyperthyroidism can affect a cat’s quality of life and potentially shorten it.

What is hyperthyroidism?
A cat has two thyroid glands, one on each side of the throat below the larynx or voice box. In a healthy cat, these glands are small and difficult to feel. In a cat with hyperthyroidism, these glands are enlarged due to an overgrowth of tissue. This tissue is functional and produces thyroid hormones. Chemical assay of an affected cat’s blood will show an excess of thyroxine (T4).

Most of these growths are benign – only 2% of hyperthyroid cats have cancerous tumors at the time of diagnosis (Reference 1).

Hyperthyroidism in Cats – what you may notice

  • Weight loss
  • Increase in vocalizing
  • Hyperactivity
  • Increased thirst and urination
  • Unthrifty haircoat
  • Vomiting
  • Diarrhea

Hyperthyroidism in cats – causes?

Hyperthyroidism was rare in cats prior to 1970 – the first case was officially reported in 1979 (Reference 2). What has changed since the ’70’s?

  • cats are living longer
  • more cats are eating commercial cat food
  • many cats live exclusively indoors

Longer Lifespan
Humans are more at risk to form small growths on their thyroid glands as they age (Reference 1). It is likely that older cats are also more predisposed to thyroid tumors.

Diet
Soy can be found in many cat foods, particularly dry formulations. Soy inhibits some of the key enzymes in the production of the thyroid hormones.  The pituitary gland responds to the lower levels of thyroid hormones by producing TSH (thyroid stimulating hormone).  More thyroid tissue grows to meet the need for thyroid hormones.

Studies with rats have linked eating soy with thyroid tumors, but only when consuming diets deficient in iodine (Reference 2). Could iodine supplementation help?  More research is needed to determine how large a role iodine plays in feline hyperthyroidism.  Most cats are exposed to other chemicals in their environment, drinking water, and diet that also affect thyroid function. How much do these chemicals contribute to the development of feline thyroid tumors?

Cat food can linings and Bisphenol A

Most canned cat foods have a plastic coating to extend the shelf life of the food inside and guard against contamination. Many of these canned linings contain a chemical called bisphenol A or BPA.

BPA has a chemical structure that is similar to the thyroid hormones and can possibly interfere with thyroid hormone function. (Even though most of the linings are PVC, BPA can be an additive in the processing of PVC). Although the FDA says the level of BPA in cans is very low and does not present health risks to humans, the agency did ban the use of BPA in baby bottles, sippy cups and infant formula packaging in July of 2012.

Hyperthyroidism in cats – the environment

Poly brominated diphenyl ethers (PBDE) are another class of compounds that have a chemical structure similar to the thyroid hormones and are known to disrupt thyroid metabolism. PBDE’s are used as flame retardants in electronics, furniture and textiles as well as construction materials (Reference 2).

In 2004, manufacturers in the US voluntarily stopped making many of the PDBE flame retardants. However, these chemicals accumulate in the environment and have been detected in significant amounts in animals as well as humans.

Multiple studies have found that house cats have serum levels of PBDE that are about 50 times higher than that in humans (Reference 2). A study at the University of Illinois found that feral cats had a lower level of PBDE’s in their blood than house cats. This indicates that house cats are exposed to PBDE in their homes.

Further work analyzed dust samples and found higher concentrations of PBDE’s in dust from the homes of hyperthyroid cats compared with those of healthy cats (Reference 2). As cats groom, they can ingest dust and possibly PBDE.

At this time, there are not any studies that have conclusively linked exposure to a specific chemical compound to hyperthyroidism in cats. Soy, iodine, BPA and PBDE’s may or may not play a significant role in cats becoming hyperthyroid (Reference 1).

Preventing Hyperthyroidism in cats

The suggestions below will certainly not hurt your cat and may limit his exposure to chemicals that can disrupt thyroid function (Reference 2).

  • Avoid cat food products containing soy products.
  • Limit fish-flavored foods: fish contain high levels of iodine and may be contaminated with PCB, PBDE, etc.
  • Feed wet foods in foil pouches in preference to using canned food possibly lined with coatings containing BPA
  • Home cooked diets can help help avoid contamination with chemicals but consult with a veterinary nutritionist so that the diet is balanced and complete.
  • Use ceramic or glass containers for feeding and storage to reduce exposure to chemicals like BPA.
  • Use filtered water from the tap to limit exposure to chemicals.
  • Vacuum regularly to limit the dust your cat ingests.
  • Avoid cat litters with deodorizers or odor neutralizers.

Thyroxine (T4) levels are routinely checked on most senior feline blood panels. Annual or bi-annual labwork will let you know if your cat is developing hyperthyroidism. This way, you can plan for appropriate treatment before your feline friend starts to show outward symptoms.

What are the treatment options for hyperthyroidism in cats? We will look at these in the next post.

references

  1. Carney HC, Ward CR, Bailey SJ, et al. 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism. Journal of Feline Medicine and Surgery. 2016;18(5):400-416. doi:10.1177/1098612X16643252
  2. Peterson M. Hyperthyroidism in cats: what’s causing this epidemic of thyroid disease and can we prevent it? J Feline Med Surg. 2012 Nov;14(11):804-18. doi: 10.1177/1098612X12464462

 

The Link Between the Environment and Cat Behavior

Posted on by felinepurrspective_u3q4o6
A cat enjoys the scents of a summer night from his window seat.

I remember visiting the zoo as a young child. Back then, the animals’ enclosures were not the large, landscaped areas that you see today. The animals were behind iron bars with a few hides to go into, water, and maybe a tree or two. It was not uncommon to see the tigers or lions pacing repetitively back and forth along the walls of their enclosures or the giraffes continually licking the chain link fences.

These repetitive behaviors are referred to as ARB’s, abnormal repetitive behaviors. In the past few decades, zoos have found that changing captive animals’ environments to allow more natural behaviors reduces ARB’s significantly. Expressing species-specific behaviors allows an animal to control and modify its environment, ensuring survival and reproductive success. Creating a den (safe place) is an example of how an animal controls and modifies its environment (Reference 1).

Environment and cat behavior

Many cats live predominately indoor lives. Our homes are quite different than the territory of a wild cat. The indoor cat often has little opportunity to engage in typical cat behaviors such as hunting and climbing trees. It is not surprising that some domestic cats indulge in ARB’s to reduce the stress of being unable to predict and control their environment.  Overgrooming, where a cat licks or scratches her fur so much that the area becomes inflamed and bald, is one of the more common ARB’s shown by domestic cats.

Of course, a good, solid medical workup may uncover a cause for overgrooming and itchiness – perhaps kitty has a food allergy or skin infection. But it is not uncommon for some of these cases to be “idiopathic”, meaning we don’t know what the cause is.

environment and cat behavior: ARB’s

The wound on this cat’s neck comes from repeated scratching.

A study published in 2018 (Reference 2) investigated the link between the environment and cat behavior. The study followed thirteen cats who had been diagnosed with Idiopathic Ulcerative Dermatitis (IUD).  IUD presents as a crusted, non-healing ulcer on the neck, head or between the shoulders. Medical therapy including surgical excision is rarely successful. The cat scratches at the wound frequently; the wound will heal if the cat cannot scratch it, say if she wears a collar or bandage. Once the collar or bandage is removed, the cat will scratch the area again and the wound reappears. (Reference 2)

 

The research team asked the owners of the 13 cats to institute the following environmental changes:

  • Leave closets open to allow cats to use them as a hideout
  • Free access to food and water (add a fountain if the cat prefers running water)
  • Free access to a garden or balcony/window – a cat door was recommended
  • Provide access to a secure area where each cat can sleep, eat, use the litter box without competing with other cats (some cats were separated from their house mates)
  • Regularly offer new toys to the cat
  • Stop interactions initiated by owner such as carrying the cat, petting the cat. Allow the cat to initiate the interaction.

As soon as environmental changes were set up, the ARB of scratching stopped within 2 days. All cats except one healed – for this cat, the owners were not able make the environmental changes. Oral medication was given to this kitty for two months but the neck wound did not heal. The other twelve cats did not receive medication.  The research team followed these cats for two years and no relapses were noted in that time.

The environmental remedies in this study aimed to give the cat control over her environment by allowing her to exercise typical “cat” behaviors.  These are in line with the AAFP* recommendations for a healthy feline environment (Reference 3):

  • Provide a safe place <> leave closets open to allow the cats to use them as a hideout
  • Provide multiple and separated key environmental resources<>secure area for eating, sleeping and using litter box
  • Provide opportunity for play and predatory behavior <> offering new toys to the cat
  • Provide positive, consistent and predictable human–cat social interaction <> emphasize interactions initiated by the cat
  • Provide an environment that respects the cat’s sense of smell <>  access to a garden/balcony/window exposes the cat to outdoor scents and smells

Although our cats are a domestic species and have lived alongside humans for over 10,000 years, life in our homes sometimes reduces their opportunity to express behaviors typical of their wild relations. The environment and cat behavior are intertwined.  Improving the cat’s environment to encourage species-specific behaviors can reduce a cat’s stress and, in some cases, cure disease.

Note: I don’t agree with free-feeding cats even in such a situation – I think it is better to meal feed and use feeding as a positive interaction with humans. Using food puzzles and tossing kibble for the cat to hunt down allows cats opportunities to engage in foraging and hunting behaviors.

* American Association of Feline Practitioners

references

  1. Joseph P. Garner, “Stereotypies and Other Abnormal Repetitive Behaviors: Potential Impact on Validity, Reliability, and Replicability of Scientific Outcomes”, ILAR Journal, Volume 46, Issue 2, 2005, Pages 106–117, https://doi.org/10.1093/ilar.46.2.106
  2. “From Feline Idiopathic Ulcerative Dermatitis to Feline Behavioral Ulcerative Dermatitis: Grooming Repetitive Behaviors Indicators of Poor Welfare in Cats”, Titeux Emmanuelle, Gilbert Caroline, Briand Amaury, Cochet-Faivre Noëlle. Front. Vet. Sci., 16 April 2018 Sec. Veterinary Dermatology and Allergy Volume 5 – 2018 | https://doi.org/10.3389/fvets.2018.00081
  3. Ellis SLH, Rodan I, Carney HC, et al. AAFP and ISFM Feline Environmental Needs Guidelines. Journal of Feline Medicine and Surgery. 2013;15(3):219-230. doi:10.1177/1098612X13477537

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