Question 1

Anxiety

Accepted Answer

Prescription 'calm' diets are formulated with ingredients that support emotional regulation, such as L-tryptophan and milk protein hydrolysates (casein). These active ingredients work together to help reduce the signs of stress and anxiety, helping to promote a calmer demeanour in pets facing environmental or social challenges.

For comprehensive guides about anxiety management, see our articles:

Question 2

Arthritis and joint care

Accepted Answer

Joint support diets work in two key ways: managing weight and reducing inflammation. They are often calorie-controlled to help maintain a lean body weight, which reduces physical stress on aching joints. Most importantly, they are fortified with high levels of omega-3 fatty acids (specifically EPA and DHA) from sources like fish oil, and other joint support ingredients like glucosamine and chondroitin, to help reduce joint inflammation and support cartilage health.

Diet options in this category include:

Retail diets (such as Hills Science Diet Mobility and Royal Canin Joint Care) for pets that don't currently have arthritis but are at risk of developing it.
Veterinary joint care diets which are ideal for pets that are curently suffering from arthritis and need active treatment.

In both the retail and veterinary joint care diets, there are foods that combine joint support with weight control benefits, as joint issues and excessive bodyweight commonly go hand in hand.

For more information, read through our articles on Arthritis in Dogs and Arthritis in Cats and our guide to the Best dog food for arthritis.

Question 3

Dental disease

Accepted Answer

Therapeutic dental diets work in a number of ways. They may either:

Feature a unique, large kibble with a specific fibre matrix, and/or
Include specific ingredients to bind calcium in the saliva to reduce tartar build up

Unlike regular kibble, which can shatter quickly when chewed, the special design of dental foods forces the tooth to sink into the biscuit. This creates a scrubbing or "brushing" action that mechanically cleans plaque and tartar from the tooth surface, right up to the gumline.

There are retail dental dog and retail dental cat foods which have similar, but generally less effective, benefits, and are particularly useful for pets who may be at higher risk of dental disease.

For more information, read through:

Question 4

Diabetes

Accepted Answer

The primary goal of a diabetic diet is to manage blood sugar (glucose) levels. These diets are typically formulated with high levels of fibre and complex carbohydrates. This combination slows down digestion and the absorption of glucose into the bloodstream, preventing the sharp spikes and drops in blood sugar that can be dangerous for a diabetic pet. Some diabetic diets, particularly for cats, are high in protein and relatively low in carbohydrates, to help lower the requirement of insulin.

Read more in our articles:

Question 7

Heart disease

Accepted Answer

Prescription cardiac diets are primarily designed to help manage congestive heart failure. Their most important feature is strictly controlled sodium levels. This helps to reduce fluid retention in the chest and abdomen (a common complication), which in turn decreases the overall workload on the struggling heart. They are often supplemented with nutrients like taurine and L-carnitine to support heart muscle function.

For more information, see our complete guides on:

Question 8

Kidney disease

Accepted Answer

The kidneys perform a number of functions vital to your pet's health; most notably they filter waste products from the bloodstream and help to maintain the correct fluid and electrolyte balance. When enough of the kidney is damaged, it is no longer able to perform these functions, and chronic kidney (renal) disease occurs.

The most critical part of treatment for kidney failure is the use of a veterinary prescription diet. These digestible protein and amino acids to reduce the load on the kidneys and therefore reduce the levels of toxic waste products circulating in the blood. They also have reduced levels of phosphorus which can protect the kidneys from further damage and can increase life expectancy, particularly in cats.

For more information, see our complete guides to:

Question 9

Liver disease

Accepted Answer

The liver is the second largest organ in the body and performs countless vital functions such as the removal of toxic substances from the bloodstream and helping with digestion and clotting. When the liver is no longer working correctly there are widespread negative effects throughout the body. Liver failure can occur from a wide range of diseases - including toxins, cancer, viruses, and congenital conditions.

Nutrition for managing liver disease? While medication (or surgery) is the most important component of liver failure treatment, nutrition can certainly help. The liver has an amazing capacity to heal, and veterinary prescription liver diets are formulated to support the liver during this process. These diets contain controlled levels of high-quality protein to reduce the liver's workload, reduced sodium to control blood pressure, and l-carnitine to assist with fat metabolism. They also contain antioxidants and low levels of copper to minimize copper accumulation in liver cells.

For more information, see our complete guides to:

Question 10

Obesity and weight control

Accepted Answer

Prescription weight-loss diets are scientifically formulated to help pets lose fat while maintaining lean muscle. They are low in calories but high in fibre and protein. The high fibre helps the pet feel full and satisfied (reducing begging), while the high protein level ensures they lose fat, not muscle, during their weight-loss journey.

Retail dog weight management diets and cat weight management diets can also help in the weight loss journey, however they will generally be less effective than the prescription diets, and are more formulated to help your dog or cat maintain their ideal weight once they reach it.

Read more about the best diets and exercise tips in our guides:

Weight Loss Tips for Dogs
Weight Loss Tips for Cats

Question 11

Skin care

Accepted Answer

Skin support diets work from the inside out to calm sensitive skin and strengthen the skin barrier. They may be made with novel or hydrolysed proteins to eliminate food-based allergic triggers. They are also heavily fortified with very high levels of omega-3 fatty acids and other skin-supporting nutrients to reduce inflammation and improve the skin's resilience against environmental allergens.

For more information, read through our articles:

Question 12

Thyroid issues

Accepted Answer

This primarily applies to hyperthyroidism (an overactive thyroid) in cats. The prescription diet for this condition is a medical marvel - it is formulated with severely restricted levels of iodine. Iodine is the essential building block the thyroid gland uses to produce thyroid hormone. By limiting the iodine "fuel," the diet safely and effectively prevents the overactive gland from producing excess hormone, allowing levels to return to normal.

Hypothyroidism is a common condition in dogs, but a special diet is not needed.

Question 13

Urinary disease

Accepted Answer

Urinary problems are a very common presenting complaint in veterinary clinics. Urinary issues commonly seen in dogs and cats include urinary infections, idiopathic cystitis, crystalluria and uroliths (the formation of crystals and stones), and urethral blockage. Urinary disease can become a medical emergency if the urethra is blocked.

Diets for urinary disease are usually 'preventative' and suitable for to help prevent urinary disease in pets who have experienced it in the past, or to prevent it occuring in pets who might be prone due to breed dispositions. However, some prescription diets can be used as an active treatment to help dissolve bladder stones.

Urinary diets are designed to make the bladder a hostile environment for the formation of urinary crystals and stones (like struvite or calcium oxalate). They work by controlling the urine pH (e.g., making it more acidic to dissolve struvites) and restricting the minerals (like magnesium and phosphorus) that act as the "building blocks" for the crystals. Some also encourage drinking to dilute the urine.

DID YOU KNOW? Never buy a prescription urinary diet unless your vet has recommended it after testing your cat's urine. This is because different diets are specifically designed to treat different types of stones. For example, Hills Prescription Diet U/D is only suitable for treating conditions caused by oxalate or cysteine stones, and may actually make other conditions (for example, cystitis associated with struvite stones) worse.

For more information, read through our articles:

FLUTD in Cats
Best Urinary Cat Food
Urinary Issues in Dogs
Bladder Stones in Dogs

Question 14

Why do I need a vet's prescription to buy these foods?

Accepted Answer

Prescription diets are classed as therapeutic foods, meaning they are formulated as part of a treatment plan for a specific medical condition. They are not just 'premium' foods. Using the wrong diet for your pet's condition, or using one when it isn't needed, could be ineffective or potentially harmful. The prescription requirement ensures your pet is receiving the correct nutritional support as diagnosed by their veterinarian.

Question 15

How long will my pet be on a prescription diet?

Accepted Answer

This depends entirely on the health condition being managed. For some acute issues, like a gastrointestinal upset or recovery from surgery, the diet might only be needed for a short time. For chronic conditions such as kidney disease, diabetes, or food allergies, the prescription diet is a critical part of lifelong management and will likely be required for the rest of your pet's life.

Question 16

Can I still give my pet treats on a prescription diet?

Accepted Answer

It is crucial to ask your vet this first. In most cases, you should not give your pet their regular treats, table scraps, or other foods. Prescription diets are precisely balanced, and giving other foods can interfere with their effectiveness. For example, a non-approved treat could trigger an allergic reaction in a pet on a hydrolysed diet. Your vet can recommend specific therapeutic treats, or safe treats, that are compatible with your pet's diet.

Question 17

Why are prescription diets more expensive?

Accepted Answer

The price reflects the extensive scientific research, development, and clinical testing that goes into creating these foods. They are formulated with high-quality, specific ingredients in precise ratios to manage a disease, which is a complex and costly process. You are investing in a food that is a key part of your pet's medical treatment, backed by significant scientific evidence.

Question 18

My pet refuses to eat their new prescription food. What can I do?

Accepted Answer

This can be frustrating. Firstly, always transition to a new diet slowly over at least 7-10 days, gradually mixing more of the new food with the old. If they are still hesitant, try gently warming wet food to enhance its aroma. Many prescription diets also come in different textures (like a pate versus a stew) or flavours, so ask your vet if an alternative is available.

Prescription Diets for Dogs and Cats: A Vet's Guide

In this article

What is a veterinary prescription diet?

Prescription vs retail diets: What's the difference?

How do prescription diets work?

What conditions are commonly managed with veterinary diets?

Anxiety

Arthritis and joint care

Dental disease

Diabetes

Food allergies

Gastrointestinal issues

Heart disease

Kidney disease

Liver disease

Obesity and weight control

Skin care

Thyroid issues

Urinary disease

Prescription Diets for Cats by Condition

Prescription Diets for Dogs by Condition

FAQs

Why do I need a vet's prescription to buy these foods?

How long will my pet be on a prescription diet?

Can I still give my pet treats on a prescription diet?

Why are prescription diets more expensive?

My pet refuses to eat their new prescription food. What can I do?

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Tue 8 Sep 2026

Dr Carla Paszkowski BVSc (Hons)

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