Causes of Weight Loss in Older Cats

Jun 24, 2015 / Practitioner Updates / Veterinary Clinical Medicine

[skinny orange cat]

Weight loss in senior cats is a common finding that is often overlooked, but that is a poor prognostic sign for continued good health. Dr. David Williams, a professor in the Department of Veterinary Clinical Medicine, in collaboration with colleagues at Nestle-Purina, is investigating the underlying cause, useful diagnostic tests, and treatments that may help arrest or reverse weight loss in otherwise apparently healthy geriatric cats that is commonly followed by death within one or two years.

Weight loss in older cats is often readily attributed to chronic renal disease, diabetes mellitus, hyperthyroidism, inflammatory bowel disease, exocrine pancreatic insufficiency, and dental problems. However, in many cases aging cats lose weight without evidence of organic disease using readily available standard diagnostic methods.

Recent evidence has indicated that some 30 to 40 percent of cats aged 10 to 12 years have low fat and protein digestibility and subnormal serum cobalamin (vitamin B-12) and tocopherol (vitamin E). Despite this clear evidence of nutrient malabsorption, these cats often have no signs of gastrointestinal disease other than insidious weight loss.

The decline in intestinal function and associated weight loss begins as soon as 8 years of age in some cats. Dr. Williams’ studies have also shown that most of these cats also have a component of concurrent protein-losing enteropathy, even though serum albumin is usually normal. Recent studies have revealed associations between changes in the intestinal microbiome and many of the above-mentioned abnormalities.

A physical exam, blood cell count, serum chemistry, urinalysis, and fecal parasite testing should be evaluated when dealing with a case of senior cat weight loss. Since senior cats often have concurrent problems, all potential associated diseases should be considered.

To investigate malabsorption further, clinicians should evaluate gastrointestinal function by analysis of serum trypsin-like immunoreactivity (fTLI), pancreatic lipase (fPL), cobalamin and folate, and perhaps tocopherol, which can provide evidence of intestinal and pancreatic disease. Pancreatic abnormalities are commonly found in association with the idiopathic chronic enteropathy (ICE) in these cats.

None of the tests for this enteropathy is perfect, so if no other explanation for the weight loss can be found a presumptive diagnosis of ICE is reasonable. Initially a diet change, perhaps with probiotic supplementation, can be used. Dr. Williams recommends a low-carbohydrate diet initially. If this does not appear to help, diets with different fermentable fiber contents may be helpful.

If low serum cobalamin, folate or tocopherol were detected, supplementation with vitamin E and other antioxidants may be beneficial.
Antibiotic treatment with metronidazole or tylosin is often impractical in cats, so when aggressive treatment is needed glucocorticoid therapy with prednisolone is recommended.

The underlying cause of the problems in these ICE cats is currently unknown. However, it should be considered in any older cat with weight loss, irrespective of the presence or absence of other signs of gastrointestinal disease.

Investigations are ongoing, and Dr. Williams is happy to consult on management of any suspected affected cats.