Managing comorbidities in senior cats

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As cats age, they are more likely to develop chronic conditions such as hypertension, diabetes mellitus, chronic kidney disease, and hyperthyroidism. In some cases, multiple diseases develop. These comorbidities are sometimes at odds with each other and can create a more complicated situation for veterinarians who are trying to diagnose and treat concurrent diseases. During a session at the 2023 American Veterinary Medical Association Convention in Denver, Colorado, Stuart Walton, BVSc, MANZCVS, DACVIM, clinical assistant professor at the University of Florida, discussed tips for managing common comorbidities in senior cats.¹

Diagnosis of Age-Related Conditions in Cats

Cats are notorious for hiding early signs of illness. In his talk, Walton stressed the importance of wellness examinations and tracking trends over time. “It is paramount that we look at elderly cats as a whole rather than having an organ or body system approach,” he said, emphasizing that if we are too focused on a single system, we could miss a concurrent disease. This risk is increased when a primary disease process makes the diagnosis of additional diseases more difficult, such as with chronic kidney disease and hyperthyroidism.

Senior cats should have a complete physical examination at least every 6 months. Body weight, body condition score (BCS), and muscle condition score (MCS) should be recorded and tracked over time, according to Walton. Blood pressure and laboratory testing including a complete blood count, chemistry panel, electrolytes, thyroid, and urinalysis should also be performed regularly. All laboratory results should be interpreted in light of the patient’s clinical signs and physical examination findings.

Laboratory values should be tracked over time with particular attention paid to trends in blood pressure, SDMA, creatinine, total T4, and urine specific gravity. Performing regular testing and monitoring trends in the results can allow veterinarians to make a diagnosis before the patient shows clinical signs of illness. This maximizes the opportunity for the veterinarian and pet owner to slow disease progression and prolong high quality of life.

Finally, Walton reminded veterinarians that some disease processes increase risks of other diseases, which may require more frequent monitoring. For instance, a patient with proteinuria or hypertension should be more closely monitored for development of chronic kidney disease.

General Approach to Treatment of Comorbid Conditions

When multiple conditions are diagnosed, there are times when the treatment of each individual condition may be at odds, such as congestive heart failure and chronic kidney disease. It is essential that veterinarians evaluate the goals of treatment for each individual disease process and look for commonalities when possible.

But no matter what disease or how many diseases are being managed, Walton suggested prioritizing the following areas:

Hydration, which can be accomplished through a combination of canned food, improving desirability of water—such as with a fountain—and use of subcutaneous fluids.

Nutrition, which is essential to meet the high protein requirements of the species. Appetite can be improved with the use of appetite stimulants, antinausea medications, and prokinetics.

Analgesia, which should be multimodal.

Environmental and Behavioral needs, which are needed to maintain quality of life.

Prioritizing these items along with the individual goals of treatment for each disease will help to maximize quality of life for both the cat and their family, according to Walton.

Comorbid Disease Challenges

Chronic kidney disease and hypertension

Chronic kidney disease (CKD) is a common disease in older cats. The goal of treatment in this disease is to slow disease progression by maintaining adequate hydration and nutrition, and managing phosphate levels, proteinuria, and anemia. Hypertension is a common comorbidity that can exacerbate proteinuria and increase renal damage.

Amlodipine, the first line treatment for feline hypertension, doesn’t affect GFR or renal parameters and can be used at any stage of CKD. However, if amlodipine alone is not sufficient, adjunct medications, such as angiotensin-receptor blockers and ACE-inhibitors must be used cautiously in the presence of CKD, making treatment more challenging. Close monitoring of renal parameters and blood pressure is essential in these cases.

Chronic kidney disease and hyperthyroidism

Most veterinarians are aware that hyperthyroidism can mask azotemia, but Walton cautioned that thyroid levels can be falsely lowered in the presence of CKD, making simultaneous diagnosis of both diseases difficult. Walton noted that even if a T4 level is normal, if a thyroid slip or goiter is palpable, further diagnostics, such as a TSH level should be pursued.

Treatment of hyperthyroidism may need to be altered when CKD is also present. Diets for hyperthyroidism are not recommended in azotemic patients. Medical management with methimazole should be the first line treatment, utilizing the lowest dose of methimazole. When CKD is present concurrently, a T4 level in the upper end of the reference interval is acceptable.

Diabetes mellitus and Inflammatory bowel disease

Diabetes mellitus (DM) and inflammatory bowel disease (IBD) are 2 diseases that can be especially challenging to comanage, as the ideal treatments for both diseases are somewhat at odds with each other. The common goals of treatment for these patients are to maintain food intake and body weight, avoid hypoglycemia, and balance nutritional needs.

The presence of IBD can complicate the management of DM as it can affect insulin sensitivity and inconsistent food intake and absorption may predispose to hypoglycemia. Additionally, serum fructosamine concentrations may be decreased by intestinal loss of albumin.

The dietary recommendations for both diseases can also be challenging to meet. Most IBD patients need a novel or hydrolyzed diet, and DM requires a low carbohydrate, high protein diet. Walton noted that “there is no one size fits all [solution].” He reminded veterinarians to also monitor appetite and address nausea and vomiting.

Medical management of IBD can also affect glycemic control. Steroids are often the first line of therapy for patients with IBD, though they can lead to hyperglycemia. Walton notes that prednisolone may need to be used in the early stages of therapy and require a higher insulin dose in the short term. He recommends twice daily dosing to minimize large swings in blood glucose concentration. Once the IBD is more controlled, medications such as budesonide or chlorambucil may be good options for long term use.

Take Home Points

Older cats commonly present with multiple disease processes. These comorbidities can complicate the diagnosis and treatment of disease. Veterinarians can maximize outcomes for senior cats through regular, careful monitoring to improve early disease detection. Once diagnosed, treatment goals for each disease should be set, paying special attention to hydration, nutrition, patient comfort, and overall quality of life for both pet and owner.

Kate Boatright, VMD, a 2013 graduate of the University of Pennsylvania, is a practicing veterinarian and freelance speaker and author in western Pennsylvania. She is passionate about mentorship, education, and addressing common sources of stress for veterinary teams and recent graduates. Outside of clinical practice, Boatright is actively involved in organized veterinary medicine at the local, state, and national levels.

Reference

Walton S. Feeline your age: comorbidities in old cats. Presented at American Veterinary Medical Association Convention: Denver, Colorado; July 15, 2023.