The Final Goodbye – When to Put Your Cat to Sleep

Posted on March 3, 2024 by felinepurrspective_u3q4o6

Saying the final good bye to your cat is never easy. Medical care for cats has progressed by leaps and bounds in the past few decades and it is not uncommon for cats to live to be 19 or 20 years old. As age takes its toll and the older cat’s mind and body declines, many cat owners hope that their old friend will slip away in her sleep. Unfortunately, this does not happen often and we need to decide if it is time for euthanasia.

The word “euthanasia” comes from the Greek: “eu” or well, and thanatos, “death”, i.e. – the good death. A “good death” is the last gift we can give our cats.

The decision to put your cat to sleep is not made lightly.

The cost of medical care may be out of your reach financially and you elect euthanasia rather than have your cat suffer untreated.
You may have done all the medical treatments possible and your cat is just not responding. You must say goodbye.

But, what about the cat that clings to survival but is dwindling, still eating but not thriving? When do you say goodbye?

when to say goodbye and put your cat to sleep

In the case of the cat with the “dwindles”, it helps to make a list of what your cat does during her day. Keep an eye on these behaviors and watch for signs of apathy or disinterest.

It can be helpful to keep a calendar of your cat’s daily behavior or events (such as illness or playfulness). Each day can be evaluated as “good”, “bad” or “average”. When the “bad” days outnumber the “good” ones, it may be time to put your cat to sleep. Your veterinarian can help you with assessing your cat’s quality of life.

Last week I said goodbye to Marley, one of “The Feline Purrspective” team. Marley was a gentle, extremely sociable cat who enjoyed head rubs and treats. He was friendly with people and fairly tolerant of other cats. His health was generally good until he was about 16 years old. He will be sorely missed.

Marley’s timeline is summarized in the table below. I have highlighted the concerns that contributed to the decision to euthanize.

AGE	TIMELINE OF LIFE EVENTS
3-14 years	I adopt Marley from the veterinary technician school I attended. Marley is introduced to my 3 cats and becomes part of my household. He learns to go on morning walks and participate in the evening treat and playtime. He becomes quite adept at food puzzles. His health is good although he does seem to lose teeth at his annual dental cleanings.
14-16 years	Marley has two instances of malignant tumors on the bottom side of his tongue, which were successfully removed. His health and demeanor remain good overall: he still goes on daily walks and participates in evening treat and play time.
16-17 years	Marley’s vision and hearing begin to deteriorate. He starts to show signs of Cognitive Dysfunction Syndrome (CDS) and starts a Sam-E supplement. He stops going outside with the other cats on walks. He is still chasing treats at night but does not play with toys.
17-18 years	September, 2023: a firm, fibrous mass is found in front of Marley’s left ear. I decline surgery due to Marley’s progressing CDS. Marley is becoming less active and seems fearful of the other cats at times. He still comes for treats most nights.
18+ years	Marley turns 18 years in early February 2024 The tumor on his head has increased in size and his left eye is starting to close and squint. He spends most of his time in a heated basket, leaving only to use the litter box or to eat. He is no longer grooming himself and has stopped coming for treats at night.

Looking at the highlighted sections in the table above, you can see that going for walks outdoors and the evening treat/play time were key activities in Marley’s daily life. By the time he is 16-17 years old, he has stopped taking the daily walk but still participates in the nightly treat time. In the next year, he stops this activity.

These behaviors defined who Marley was and were indicators of his will to live. In the final months of his life, he lost this will to live. It was time to say goodbye.

the final goodbye

On February 24, 2024, I said a final goodbye to Marley. I gave him some gabapentin before taking him to the clinic for euthanasia. He passed quickly and peacefully in his basket – he was gone before finishing his favorite treat and before all the euthanasia solution was injected.

The decision to euthanize Marley was based not only on the progression of his medical condition, but also on the changes in his behavior. I feel he was not in pain but his life was no longer worth living. From a friendly, outgoing cat, he had become a reclusive, confused creature, going through the motions of surviving. I don’t feel that his last years were mismanaged but I do feel it may have been kinder to let him go a few months earlier.

I have shared my experience in the hopes that it can help other cat owners who are wrestling with this very difficult question: when to put your cat to sleep. I found it helpful to pay attention to Marley’s daily activities, and note how often he participated in them and when he just stopped doing them. Tracking these key behaviors can give you, the cat owner, an idea of your cat’s mental state: is he is still engaged in life or just going through the motions? If he is just going through the motions, is it time to say goodbye?

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Treating Diabetes in Cats – Insulin and Non-Insulin Therapies

Posted on November 12, 2023March 11, 2024 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

determine how many calories your cat is eating
reduce current calories by 10-20%
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

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
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
(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 )
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 November 5, 2023March 11, 2024 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

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
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)
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
American Association of Feline Practitioners, Diabetes Educational Toolkit, https://catvets.com/diabetes-toolkit/troubleshooting, viewed 11/2023

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Managing the Cat with Chronic Kidney Disease

Posted on September 24, 2023March 11, 2024 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:

Keep Kitty hydrated
Feed a diet that will lessen the stress on the kidneys
Maintain appetite
Manage high blood pressure
Treat anemia if necessary
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

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.
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 September 17, 2023March 11, 2024 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

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

Posted on September 3, 2023March 11, 2024 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

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
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

Arthritis in cats: a tale of biotech and a Chinese hamster

Posted on January 30, 2022 by felinepurrspective_u3q4o6

If you search for “monoclonal antibodies”, most of the search results are about COVID-19 and its variants. But did you know that monoclonal antibodies form the basis of the newest treatment for arthritis in cats? This new treatment is called Solensia. Solensia is a monthly injection for arthritic cats that won FDA approval this month. It should be available through your veterinarian later this year.

arthritis in cats: a tale of biotech and a chinese hamster

what are monoclonal antibodies?

Monoclonal: refers to a cell or organism that comes from a single individual or cell.
Antibodies are proteins in the blood that our immune system produces to counteract a foreign substance such as a bacteria or virus (think COVID-19).

antibodies and the immune system

Immune cells in our bodies called B-lymphocytes mount a response to a foreign substance or antigen (e.g. a virus), binding to it and deactivating it. The presence of the antigen and immune cells called T cells activate the B-cells. The B cells then propagate and release antibodies that are able to bind to and deactivate the specific antigen that stimulated their formation!

Monoclonal antibodies are derived from clones or copies of activated B cells. They can be harvested and grown in the laboratory and used to fight infections caused by the antigen they were developed to target.

Where do monoclonal antibodies come from?

Blood cells from convalescing patients: Due to the large numbers of convalescing COVID patients, there was a ready source of blood cells containing B-cells with antibodies to COVD 19 that could be used to make monoclonal antibodies to treat newly infected patients.
Transgenic mice: Mice that have been genetically altered to carry human antibody genes instead of mouse antibody genes are the usual source for monoclonal antibodies. These mice can be injected with a specific antigen and produce fully human antibodies that can be used by human patients to combat that antigen. Being human antibodies, they are less likely to be rejected by the human immune system.

Arthritis in cats: using monoclonal antibodies

Nerve growth factor (NGF) is a protein that is key to the development and survival of nerve cells or neurons, particularly sensory neurons that transmit pain, temperature, and touch sensations.

When NGF binds to pain receptors inside the sensory neuron, a series of events is triggered that ultimately sends a “pain” signal to the brain.

Instead of binding to a structure on a virus, monoclonal antibodies can be developed to recognize and attach to NGF, preventing NGF from binding to the pain receptors on the sensory neruron, blocking the pain signal.

Motion is Medicine

A reduction in pain means our arthritic cats will be more likely to move around more. Increased mobility will strengthen the cat’s muscles, so they can better support and assist the deteriorating joints. Increased activity and reduced pain result in a better quality of life.

Biotech Magic

The active ingredient in Solensia is frunevetmab, a monoclonal antibody that targets NGF. The antibodies are sourced from Chinese hamster ovary cells. Like the mice that have human antibodies instead of mouse antibodies, the hamster cells are “felinised”using recombinant biotechnology. Sections of the hamster antibodies are replaced with their feline counterparts. “Felinization” ensures that the cat’s immune system will not reject the monoclonal antibodies but allow them to function as part of the cat’s immune system.

Of cats and hamsters: no hamsters harmed

Frunevetmab is sourced from the cells of Chinese hamster ovaries. In fact, cells from an individual Chinese hamster, harvested back in the 1950s, produced the cell line which dominates biotechnology today. These cells are easy to propagate and maintain in the lab, providing a ready source of monoclonal antibodies.

multimodal therapy for arthritis in cats

Solensia is a pain medication and does not directly aid in preserving the synovial tissues. Most likely, Solensia will be part of a multimodal treatment that will include drugs and supplements like Adequan or glucosamine that are thought to help maintain synovial tissues in addition to weight loss and exercise.

Unlike other arthritis pain treatments such as NSAID’s, monoclonal antibodies are eliminated in the same way other proteins are, with minimal effect on the kidneys and liver, a concern for our cats with Chronic Kidney Disease.

Treatment using Solensia will consist of monthly injections under the skin. Most cat owners can become proficient in giving subcutaneous injections and treatment can be done in the safety and comfort of the cat’s home.

Thanks to a Chinese hamster years ago and advances in biotechnology, our cats may be able to spend their “ golden years” without pain from osteoarthritis!

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Measuring your cat’s blood pressure: why and how

Posted on December 12, 2021 by felinepurrspective_u3q4o6

You’ve brought your senior cat in for her regular checkup and the technician asks you if you would like to have her blood pressure checked. Although your blood pressure is routinely checked when you go to the doctor, it has not occurred to you to ask to have your cat’s blood pressure checked. Should you have your cat’s blood pressure measured? How is it done – will it be uncomfortable? Frightening?

Why measure your cat’s blood pressure

As cats age, many develop hyperthyroidism and kidney disease. Other cats may develop diabetes. All of these conditions can result in the heart pumping harder to compensate for the changes. As the heart pumps harder, blood pressure increases and arteries, the eyes, the kidneys, the brain and heart can be damaged.

Left untreated, high blood pressure can result in:

blindness
increasing loss of protein through the kidneys >> shortened life span
disorientation, lack of balance, seizures, altered mentation or behavior, or weakness in the limbs

The best way to avoid these consequences is to monitor your cat’s blood pressure and start treatment if his blood pressure is high.

So how do we measure your cat’s blood pressure?

When measuring blood pressure in humans, we typically place a pressure cuff on the upper arm, inflate the cuff until the flow of blood to the artery is shut off . The cuff is then released, and a wave of blood fills the artery, turbulent at first, then subsiding to a smooth flow.

The human practitioner can use a stethoscope to listen to the sounds made as the blood rushes back into the artery.

The first sound is heard at the systolic blood pressure (the higher number in 120/80)
The final sound is heard at the diastolic pressure (the lower number in 120/80).

We will also use a blood pressure cuff to measure your cat’s blood pressure. This cuff can be put:

on the front leg
on the hind limb, above or below the hock (ankle)
on the tail

Cats’ arteries are much smaller than humans’ and it is difficult to hear the sounds of the blood flow using a stethoscope, so we turn to other methods: Doppler and oscillometric.

Doppler

A Doppler unit measures blood flow.

After placing the cuff on your cat, the Doppler sensor is placed over the target artery.
Piezoelectric crystals in the sensor detect changes in the flow of blood in the arteries and convert these to sound.
Acoustic gel on the sensor ensures good contact so that the practitioner can hear the heartbeat.
The cuff is inflated until the heartbeat is no longer heard.
The cuff is then released and the pressure at which the heartbeat can be heard again is the systolic blood pressure.
Headphones are usually used when measuring blood pressure with a Doppler.

Doppler units give us a measurement of the systolic blood pressure, the larger number in the 120/80.

Oscillometric

Only a cuff needs to be placed to measure your cat’s blood pressure with an oscillometric unit.

A sensor in the cuff detects the pressure pulses in the artery.
As the cuff is inflated, the pulses decrease as flow to the artery is cut off.
The cuff is then deflated and the pressure wave that results as the blood rushes back into the artery is analyzed.

Oscillometric units typically only measure the peak of this wave, the average blood pressure, and calculate the systolic and diastolic pressures.

A High Definition Oscillometric unit records the entire pressure wave, directly measuring the systolic and diastolic pressures. An HDO unit is usually connected to a computer to view the pressure wave and determine if the measurement was accurate.

How accurate is a blood pressure if my cat is nervous at the vet clinic?

Just like people, cats get anxious and nervous when visiting the vet clinic. Blood pressure is sensitive to this and it can be a challenge to measure your cat’s blood pressure.

Putting the odds in our favor:

Most of the time, you should be with your cat during a blood pressure measurement. Your cat knows you and trusts you. Your presence is reassuring and calming.
Allow your cat to settle in for 5-10 minutes – the measurement should be done in a quiet room.
If your cat likes to snuggle in your lap, see if the measurement can be done there. If your cat prefers to sit on his stomach, perhaps a tail measurement is best. If he is comfortable laying on his side, a hind leg may be better.
Using the front leg to measure blood pressure puts the practitioner in front of the cat; curious cats may want to take a nibble at the blood pressure cuff. I prefer that your cat be facing you, her person, who can reassure her. I feel the tail and hind leg work better.
The artery being measured, tail or hind leg, should be at the same level as the heart – so kitty should not be sitting up, but laying comfortably on his stomach or side.

What do the numbers mean?

Again, like people, the systolic pressure is ideally around 120.
Pressures 150 and over can indicate the need for medication.
Your vet may also do an eye exam, looking at the eye with an ophthalmoscope or lens. In some instances of high blood pressure, the vessels in the eye dilate and become twisted; sometimes the retina may be detached, resulting in blindness. If high blood pressure is caught early enough, blindness may resolve with treatment.

My cat’s blood pressure is high but her eyes looked OK. What next?

High blood pressure can be treated with drugs – the most common drug used is oral amlodipine. Amlodipine takes effect fairly quickly and a blood pressure can be repeated in about 10 days and the dose adjusted if needed.
Other medications such as benazepril or telmisartan may be used alongside or in place of amlodipine.

I don’t think the reading was accurate – my cat was too nervous

It is worth investing in a home blood pressure visit. A practitioner can come to your home and get a measurement where your cat feels safe and secure.

Measuring your cat’s blood pressure especially as she gets older will help keep her healthy and comfortable. Without treatment, high blood pressure can have serious side effects, including blindness, seizures, and cardiac damage.

Have your cat examined regularly by your veterinarian, as changes to the eyes or a heart murmur might warrant a blood pressure check.

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