Understanding Prescription Cat Food for Specialized Diets

Kirsten McCarthy / Cats.com

Prescription or therapeutic veterinary diets are specifically formulated to treat or support health issues in cats. In some cases, they may be the only treatment your cat needs. Specialized diets play an important role in the treatment of many conditions, including chronic kidney disease, urinary tract problems, diabetes, hyperthyroidism, gastrointestinal problems, and obesity.

The balance of nutrients in prescription diets is very different from normal diets – meaning they are usually not appropriate for healthy cats. As a result, they should be prescribed by a veterinarian and used under their supervision, just like a medication.

Read on for everything you need to know about prescription diets, from how they work to what they are used for.

What are Prescription Diets?

Prescription diets are specialized therapeutic diets formulated to treat or manage a certain health condition. They contain specific nutrients in a certain formulation that are beneficial to that medical problem.

Unlike normal cat food, the Association of American Feed Control Officials (AAFCO) does not require prescription diets to be balanced or complete for a healthy cat. This is because cats with specific health conditions have different nutritional needs from healthy cats, often requiring higher or lower levels of certain nutrients. Therapeutic diets may also contain extra nutrients to help the condition they are treating.

Some prescription diets work by causing a change to your cat’s normal physiology which is helpful to their condition. An example is urinary care diets which alter the normal pH of your cat’s urine to prevent or dissolve bladder stones.

However, prescription diets can be inappropriate – or even harmful – for cats without that condition. Prescription diets are an important part of your cat’s treatment plan. So – just like a prescription medication – they must be prescribed by your vet and used under their careful supervision.

Common Prescription Diets for Cats: A Vet Explains

Prescription diets are a mainstay in the treatment of kidney disease, urinary tract problems, obesity, and food allergies in cats. Kirsten McCarthy / Cats.com

Appropriate, high-quality nutrition is important for the management of any health issue. However, there are certain diseases and conditions where using a specialized prescription diet is known to make a significant difference. This section contains everything you need to know about the most common prescription diets I recommend as a veterinarian.

1. Chronic Kidney Disease

Starting your cat on a specialized kidney diet is the best treatment for chronic kidney disease (CKD) – even more so than any medication. They help cats live longer with fewer symptoms and a better quality of life by meeting specific nutritional needs.

Compared to regular pet foods, prescription kidney diets contain:

• Reduced protein: Healthy cats require high levels of protein. But cats with CKD struggle to eliminate the waste products caused by breaking it down. Instead, these waste products build up in the blood (uremia) and can cause them to feel unwell. Kidney diets contain lower amounts of protein to reduce this but use high-quality sources to avoid muscle wastage.
• Reduced phosphorous: Excess phosphorous is excreted in urine, but cats with CKD struggle to do this, leading to high levels in the blood, which can worsen the disease. Reduced phosphorous levels slow the progression of the kidney disease, helping your cat live longer with fewer symptoms.
• Reduced sodium (salt): Too much sodium can overwhelm the kidneys in cats with CKD, worsening high blood pressure and causing fluid retention. So, low sodium diets manage fluid balance and blood pressure.
• Increased fat: kidney diets contain increased fat to help your cat eat enough calories and maintain their weight. It also improves the taste, as cats with CKD often struggle with poor appetite.
• Increased potassium: Cats with CKD are prone to low potassium (hypokalemia) due to increased loss in their urine and reduced intake through poor appetite or vomiting. Kidney diets contain increased amounts to compensate for this.

Prescription renal diets for cats also contain a whole host of extra nutrients, including omega-3 fatty acids, antioxidants, beta-carotene, acidifiers, buffers, and additional vitamins and minerals.

2. Feline Lower Urinary Tract Disease

Prescription urinary care diets are formulated to reduce the risk of Feline Lower Urinary Tract Disease. Yaya Photos / Shutterstock.com

Cats are prone to lower urinary tract problems, from urinary tract infections (UTIs) to stress cystitis and uroliths (bladder stones) – which can lead to a blocked bladder, a life-threatening condition. Collectively, these are called ‘Feline Lower Urinary Tract Disease’, or FLUTD. There are many commercial diets aimed at reducing FLUTD in cats. While they differ depending on what condition they are treating, they have some common goals:

• Dilute the urine: Cats naturally have concentrated urine, but we know this puts them at risk of urolith formation and increases inflammation in their urinary tract. Diets that dilute the urine significantly reduce the risk of FLUTD.
• Reduce uroliths: Prescription diets control the pH of the urine to prevent certain types of uroliths from forming (some diets can even dissolve them). They also promote the activity of your cat’s natural urolith inhibitors. The vitamins and minerals (such as calcium, phosphate, and vitamin D) are balanced to reduce the risk of certain uroliths, especially calcium oxalate.
• Reduce stress: We know stress plays a significant role for many cats who suffer from recurrent FLUTD. Recent prescription FLUTD diets contain substances such as alpha-casozepine and tryptophan that can help reduce stress, and therefore FLUTD.

Many prescription diets for recurring FLUTD are designed to be fed long-term. However, diets designed specifically to break down a certain type of urolith (such as struvite) are for short-term use only.

3. Weight Control

Helping your cat reach a healthy weight can add years to their life – but it is often easier said than done! Weight control diets are formulated to reduce your cat’s calorie intake by containing reduced calories and fat. This encourages their body to use their fat stores for energy, helping them to lose weight.

However, cats often struggle with hunger between meals on a calorie-restricted diet. Satiety diets contain increased fiber to help them feel full between meals, reducing hunger and attention-seeking behavior. This makes the weight-loss process easier for both of you.

Importantly, satiety diets contain high levels of high-quality protein to help your cat maintain muscle mass while losing weight. They also have a high concentration of vitamins and minerals, so your cat still gets everything they need, despite eating fewer calories – which can be an issue if you simply feed them less of their normal food.

4. Allergies

Prescription hypoallergenic diets can be used to both diagnose and treat food allergies in cats. Kirsten McCarthy / Cats.com

A diet trial is the most effective way to diagnose (or rule out) a food allergy in your cat. The most common food allergens are proteins – usually the meat element. So, prescription hypoallergenic diets contain proteins that have been processed (hydrolyzed) so the body does not react to them. They are different from non-prescription or ‘over the counter’ diets which may use the word ‘hypoallergenic’ but would not be suitable for a diet trial.

Some prescription hypoallergenic diets are designed only to be fed for the diet trial to test if your cat’s symptoms resolve. However, some hypoallergenic diets are complete and can be fed long-term to sensitive cats.

They may also contain other ingredients that help cats with food sensitivities, such as fatty acids to strengthen the skin barrier or probiotics for gut health.

How To Feed Prescription Diets

Prescription diets are important to your cat’s treatment plan. It can be helpful to think of them as a form of medication. Like medication, they must be prescribed by your veterinarian and used under their guidance.

Starting a Prescription Diet

Your veterinarian will recommend a diet specifically tailored to your cat’s needs. But for many prescription diets, there are a few different brands, textures, and flavors available. So, try a few to see which your cat likes best. You can purchase prescription diets directly from your veterinarian, but you may also be able to find them online or in pet stores.

As always with any change in diet, you should transition your cat gradually onto their new food, mixing in a little more each day, over 10-14 days. Contact your vet if your cat shows worrying symptoms on their new food, such as diarrhea.

Feeding as a Sole Diet

As prescription pet foods are calculated to contain a precise balance of nutrients for your cat’s condition, they should be given as your cat’s sole diet. Unfortunately, this means no extra treats or titbits! However, some common prescription diets will have a range of treats available that are safe to use at the same time.

Feeding Prescription Diets With Other Cats at Home

Feeding a specialized diet can be tricky if you have more than one cat, you may need to feed them at different times in different rooms. Kirsten McCarthy / Cats.com

If you have more than one cat, you might be worried about feeding different diets. However, some prescription diets are safe (if a little expensive!) to feed a healthy cat too. For instance, most prescription gastrointestinal diets will meet the nutritional needs of a healthy cat but be extra digestible and easy on the guts. So, check with your veterinarian if you can feed all your cats the same diet.

But don’t worry, even if the prescription diet is not appropriate for your other cats, eating some occasionally won’t cause any issues.

Long Term vs Short Term Diets

Check with your veterinarian if the diet is intended for short or long-term use. Cats with chronic health conditions, such as CKD or hyperthyroidism will likely need a specialized diet for the rest of their life. But other diets are only designed to be used for a little while and won’t meet your cat’s nutritional needs long-term.

Monitoring Cats on Prescription Diets

Your cat will likely need some ongoing monitoring for their health condition. So, monitoring once they have started their new diet will form part of this. Depending on their condition, they may need regular check-ups, or blood or urine tests, to see how the diet is working.