Diets for Pets with Specific Illnesses

Pete Wedderburn
19th April 2021 - 4 min read

Most pet food that’s commercially available is designed for healthy pets. However, when a dog or cat has some illnesses, we know that their nutritional requirements are sometimes different.

veterinary diet dog bowl

Specialised pet food manufacturers have identified that there is a specific need here, and they have formulated diets that have been custom-made to suit animals with specific conditions. If those diets are fed to healthy pets, they may not cause any particular issues, but the nutrition will not be ideal for them. For this reason, a decision has been made that it’s better to restrict the distribution of these diets to vet-only channels.

The aim is to ensure that the disease-specific diets are only supplied to animals that have the particular needs for which the diets have been designed. That’s why they are called “veterinary” or “prescription” diets.

There is a long list of conditions for which special diets are available. The Purina Pro Plan for Dogs and Purina Pro Plan for Cats covers the most common issues.

Kidney Disease

Kidney disease is one of the most important: we know that cats with chronic renal failure (a common problem in elderly felines) can have their remaining life expectancy doubled if they are kept strictly to a diet designed for cats with kidney disease such as Purina Proplan Renel Cat Food The same general rule applies to dogs. The Purina Proplan Renal Dog Food has specific characteristics: restricted levels of phosphorus, limited amounts of high-quality protein, enhanced levels of omega-3 fatty acids, as well as other features.

Bladder Stones

Bladder stones are surprisingly common in pets: substances in the urine crystallise together, forming solid stones a bit like those large crystal stones that you can buy as ornaments. You can imagine that a large stone in the bladder will cause discomfort as well as signs of illness in an animal. In the past, surgery to remove such stones was the only answer: these days, special diets are available that change the chemical composition of the urine, allowing any bladder stones to dissolve naturally, over weeks and months. The Pro Plan UR Urinary Dog Food for dogs or Pro Plan Ur Urinary Cat Food is designed to prevent these crystals from developing in the first place.


Diabetes is a condition that can affect pets as much as humans, with daily injections of insulin being needed. Diet is an important additional way of helping to stabilise affected animals, so it’s possible to buy special formulations designed for diabetic pets. The Pro Plan DM Diabetes Management Dog Food or Pro Plan DM Diabetes Cat Food contains lower levels of carbohydrates than standard diets, provoking less of a spike in blood glucose levels after meals.


A gastro-intestinal diet has also been created, with low-fat levels and highly digestible ingredients. For any animal suffering from gastroenteritis, The Pro Plan ENGastrointestinal Dog Food or Pro Plan ENGastrointestinal Cat Food is often recommended by vets to assist a rapid recovery towards normal. Affected pets can then gradually have their normal diet added to the special diet as their gut resumes normal health. Proplan fortiflora probiotics can also be given to aid the return to a healthy gut microbiome.

grey cat eating food from white bowl

Food Allergies

Food allergies can make pets itchy, as mentioned before. The only way that a diagnosis of this problem can be made is to feed a trial diet that is highly unlikely to prompt an allergy. If the pet stops itching, then you have proven that the diet was the cause. It’s possible just to feed a restricted protein diet, with rare ingredients that are unlikely to provoke a reaction (e.g. venison and potato). However, a new alternative is to feed a special hydrolysed diet, such as Pro Plan HA Hypoallergenic Dog Food or Pro Plan Hypoallergenic Cat Food which has been treated in the pet food factory so that all of the protein has been chopped into short chains at a molecular level. The immune system is unable to have an allergic reaction to such short chains of protein. Feeding this type of diet is a short-cut to diagnosing food allergy: an allergic pet will usually stop itching within days of being fed nothing but this special food, allowing the diagnosis to be confirmed.


As well as this anti-allergy diet, so-called “skin diets” are available such as Pro Plan DRM Dermatosis Dog Food these have ingredients designed to optimise skin health, with added ingredients such as omega-3 fatty acids, zinc, and other specific nutrients.

Dementia or Cognitive Disorder

In older pets, dementia (or “cognitive disorder”) is increasingly common. So-called “neuro-diets” such as Pro Plan NC Neurocare Dog Food contain ingredients chosen because they support the brain’s metabolism, and in theory at least, they should provide optimal support for an elderly brain that’s beginning to fail.