Special diets support pets with kidney and liver disease
(July 1, 2025) — As I mentioned in last month’s column on pet foods, certain health conditions sometimes dictate a change in diet, such as allergies, kidney and liver disease, to name a few.
Chronic kidney (renal) disease frequently necessitates a diet change to help off-load the work the kidneys need to do to excrete toxins in the body.
Renal diets work by lowering the amount of phosphorus (which is not excreted properly in patients with renal disease), sodium, and protein ingested, to help minimize progressive damage to the kidneys from mineralization, direct toxicity and hypertension.
Also, renal diets supplement potassium – a vital electrolyte that patients with kidney disease will urinate in excessive quantities due to the increased urine output of renal patients.
Omega-3 fatty acids are beneficial as antioxidant support to help kidneys as are supplementation with B complex vitamins. Prescription renal diets are specially formulated to address all these needs. Palatability is paramount. Home-made versions of a proper renal diet can also be formulated by a veterinary nutritionist.
Liver (hepatic) disease, in general, does not require a specific diet change until and unless the liver changes are severe and end-stage, and causing a neurologic problem called hepatic encephalopathy.
Even so, a good quality, highly digestible food is ideal to make sure the pet has adequate nutrition which can help slow progression of disease. Sometimes addition of antioxidants is recommended to help with that as well (vitamin E, S-adenosyl-methionine or SAMe, milk thistle).
Pets with certain types of liver disease – such as copper storage disease – may need limitations of specific ingredients, but this would be addressed by your veterinarian/veterinary internist.
If progression to hepatic encephalopathy occurs, your veterinarian will start limiting protein quantity. This will minimize ammonia absorption, which is not well tolerated by a poorly functioning liver and can lead to the neurologic signs seen with hepatic encephalopathy.
Allergies to foods can manifest with gastrointestinal signs or itchy skin and recurrent skin/ear infections. Itchy skin (also known as pruritus) is less commonly associated with diet than with skin parasites like fleas, or with inhaled allergies – especially if the clinical signs are seasonal.
Our pets’ version of hay fever, for instance, is much more likely to be seen as severely itchy skin, ears and paws. Having said that, if parasites and seasonal allergies are completely ruled out, a diet trial may be warranted to help identify a food allergy.
Food allergies happen following a long time of eating the same food rather than an acute reaction to a new food, so diet trials typically last 6-8 weeks of feeding a single novel (meaning not previously fed to this animal) protein to see if a new protein source will alleviate the itching.
If there appears to be success with the diet change, a feeding challenge can be done by refeeding the suspected offending protein to see if it causes recurrence of itching. Many opt not to do the challenge part once itching has been resolved, they choose to move forward with a new protein source from a balanced product.
There are commercially available foods that have what are considered novel proteins, such as rabbit, venison, duck, certain fish, bison, alligator or kangaroo meat in them, instead of more commonly fed proteins. A new one, get this, is even made from black soldier fly larvae.
Another option is to feed what is called a hydrolyzed protein diet, where the protein is essentially broken down to its component parts to hopefully not be recognizable to the gastrointestinal tract as an offending protein.
Lastly, sometimes dogs and cats can have trouble with more processed foods, such as kibble and might benefit from a switch to one of the frozen commercial foods I mentioned last column – even if they contain a protein the animal had been eating.
Two I have used with success over the past few years are Just Food For Dogs and Chi Dog, though there are a few others. This condition could be compared to the rise in gluten allergies in people associated with excessive processing of grains.
Hopefully this was an informative quick peek at certain specific diseases that can be helped utilizing specialized diets. You will want to work with your veterinarian if your pet has a condition that might benefit from considering a prescription diet or other specialized diet.
Email questions and comments for Micki McCabe Walls to drmccabevet@gmail.com
Related story: Taking stock of traditional pet foods

Micki McCabe Walls
Micki McCabe Walls, DVM, DACVIM, FAAVA, is a long-time Clayton resident. The recently retired local veterinarian has an interest in internal and integrative medicine.