Managing renal disease in cats - Veterinary Practice
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Managing renal disease in cats

RICHARD BYRNE reports on a recent CPD seminar on a common condition

RENAL disease is one of the most common diagnoses made in general practice and approximately a third of cats over the age of 15 have the condition. It is often subclinical in cats and therefore it can be difficult for vets to diagnose, as cats may show either no or few signs of illness until the disease is advanced.

Bayer Animal Health, manufacturer of Renalzin, a feed additive for the management of chronic renal disease (CRD), recently hosted a series of CPD meetings featuring Dr Sarah Caney, an RCVS specialist in feline medicine.

With topics covering early diagnosis, diagnostic testing, reassessments, treatments and support for clients, the meetings highlighted some important pointers for veterinary surgeons to utilise in their practices.

Clinical signs

Cats are masters of disguising illness and those with renal disease may show gradual weight loss as their only clinical sign, which often goes unnoticed by their owners. Other common signs to look out for include dehydration, lethargy and weight loss – unfortunately some of the least specific clinical signs an ill cat could show.

Polydipsia and polyuria, which are regarded as some of the main clinical signs in canine CKD, are reported less frequently in cats, perhaps due to their lifestyle or because many cats have the ability to retain greater urine concentrating ability than dogs. Additional signs may include vomiting or signs of nausea, anaemia, signs referable to systemic hypertension and oral ulceration.


As the condition is often subclinical and therefore difficult to diagnose, veterinary professionals should be proactive in identifying renal disease. Cat owners need to be educated on the importance of regular check-ups, particularly in cats at risk of the condition.

A thorough physical examination should be performed, making sure that a weight check and body condition score are recorded at every visit in addition to assessment of hydration status, mucous membranes and oral cavity, an ophthalmic examination and blood pressure measurement.

It is advisable to consider routine urinalysis as part of an annual health check for all cats over seven years of age. Annual blood screening can be justified in all cats over 11 years as a third of cats over 15 have kidney failure. Because of their susceptibility to renal disease, these cats should ideally have check-ups twice a year.


The International Renal Interest Society (IRIS) has developed a classification system that distinguishes clinical stages of chronic renal disease. These stages correspond to progressive decreases in renal function, as reflected by decreasing glomerular filtration rate and increasing serum creatinine levels.

It is advisable that clinicians use the IRIS desired phosphate levels and not laboratory reference ranges when assessing and treating patients.

Owner awareness

Often clients are reluctant to bring their cats into practices, even for preventive care. However, there are some strategies that can be developed to increase contact with mature, healthy cats.

These include extending booster consultations and combining vet and nurse booster consultations in conjunction with a pre-consultation health questionnaire to obtain the history in a time-efficient way.

Dedicated senior and geriatric clinics can also be held to encourage owners to bring their cats into practices and educational literature should be utilised both in practices and on practice websites.


It is important that each cat is treated as an individual, as all cats are different in the complications associated with the condition. Providing individual treatment increases the best chance of optimum care.

Owners should be advised that the renal damage that has already occurred is irreversible, although long-term management can have a good prognosis. Current treatment options are aimed at improving the quality and length of life of the affected cats.

Dietary management is the single most beneficial treatment for cats with kidney disease and phosphate restriction has a significant effect on the survival of cats. Felines that will readily eat a renal prescription diet will live on average twice as long as those that will not.

For cats that will not eat a renal prescription diet, feed additives such as Renalzin ( can be added to a cat’s preferred food to restrict phosphate. Renalzin is the only phosphate binder on the market that has no contra-indications.

Diets can be slow to be accepted and it is often useful to use a phosphate binder in a cat’s regular food while introducing or trialling different diets. If a diet or binder is not readily accepted, stop for a couple of days but persevere in the long-term.

Do not expect to see a reduction in phosphate levels straight away. However, both veterinary surgeons and clients must persevere as this will slow the progression of the disease and will prolong the lifespan of the cat.

Regular monitoring can help identify new problems which may be essential in ensuring the best long-term care of cats with renal disease.

Monthly check-ups are advocated, where possible, to allow early detection and treatment of problems. These consultations enhance client communication and greatly improve the chances of optimal treatment.


Kidneys perform many different, vital functions and management of cats with renal disease is not straightforward. Thorough assessment, treatment and monitoring are required to ensure that optimal therapy is being achieved, which should be tailored to each individual cat.

In spite of the progressive nature of renal disease, treatment can be incredibly rewarding not only to the cat and owner but also to the veterinary professional involved in the management of the case.

To obtain maximum results, owners should be encouraged to be as involved as possible, not only for the well-being of their cat, but also so that they feel they have done as much as they possibly can to extend the life of their pet.

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