Ginger cat at the vet with owner

Don't feed a cat's prescription diet to a dog – and vice versa.

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What is a prescription diet?

By Dr Hester Mulhall MA, VetMB, MRCVS Veterinarian

Updated on the

These special diets are made just for your pet, but how do you get them and what's in them?

A ‘prescription diet’ is a term that refers to a pet food that is designed to form part of the treatment plan for a specific medical problem. Similar diets are often referred to as ‘therapeutic diets’ or 'veterinary diets'. These diets are specially formulated, so that they contain the right balance of ingredients to help treat or manage a certain condition. As they might include less or more of specific nutrients than a normal healthy animal would require, they should only be fed with the recommendation of a vet.

Do you need a prescription to buy a therapeutic or prescription diet?

No, somewhat confusingly. Neither require a prescription. Having said that, therapeutic diets are generally available through vet practices or specialist retailers. Always check with a vet before feeding your pet a therapeutic diet, as it may not be suitable for your pet and could exacerbate a health problem if fed incorrectly.

Why do vets recommend prescription diets?

This depends on the medical condition that the diet is being recommended for. There is a large range of therapeutic diets, including those to help manage kidney disease, obesity, food allergies, bladder stones, diabetes, heart disease, digestive problems and more. Each diet will have properties that have benefits for a specific condition. A vet will recommend a therapeutic diet because there is evidence to show that they can be effective as part of a treatment plan, either on their own or alongside other medication.

Why do I need a prescription diet for my dog?

If a vet has recommended a prescription diet, but it is unclear why, you should ask the vet for more information. There is a large range of diets that are designed to benefit different illnesses or health problems.

Is prescription dog food necessary?

A vet may recommend a therapeutic diet if their clinical reasoning suggests that it would be a useful part of a treatment plan for your pet. In some cases this will be considered essential, if your dog has a condition that can be made worse by a regular diet. For others, this will be part of a ‘gold standard’ treatment plan. This means that ideally you would feed the recommended dog food, but if this is not feasible due to constraints (financial or otherwise), then the vet may be able to offer you an alternative management plan.

Always discuss this with a vet, as they will be able to advise how essential the diet is for your pet and whether there are any alternatives. Do not try to re-create a diet at home or feed an alternative without consulting a vet. The diet can form a very important part of managing your pet’s health.

If feeding a prescription diet recommended by a vet, you should avoid feeding treats or other foods that might upset the balance of nutrition, which is finely adjusted to support your pet.

Do you need a prescription for Purina Pro Plan?

No, neither Purina Pro Plan nor Purina Pro Plan Veterinary Diets require a prescription from a vet.

Is FortiFlora a prescription-only product?

No, to get hold of FortiFlora does not require a prescription.

What is Purina FortiFlora used for?

Purina FortiFlora is one of the brands of veterinary probiotics that are available. It is designed to support gastrointestinal health.

How long does FortiFlora take to work?

This depends on the individual and why they are taking FortiFlora. If your pet is showing gastrointestinal symptoms such as diarrhoea, you would expect to see some improvement within three to five days.

Can cats have dog FortiFlora?

No, the cat and dog FortiFlora have different formulations, so you should not give the dog version to a cat – and the same is true vice versa.

What is a veterinary diet?

A veterinary diet is simply another term for a prescription diet or therapeutic diet.

Can too much of probiotics cause diarrhoea?

Any novel food can cause digestive upset. With probiotics in particular, the quality of the probiotic should be considered. There is more evidence to support the use of some types than others. Diarrhoea has many causes and not all are dietary related.

Although probiotics may be used to treat diarrhoea, there is evidence to show that they can cause diarrhoea as a side effect in rare cases. If your pet has developed diarrhoea following any treatment, you should speak to a vet.

Is a prescription diet for a cat and dog the same?

Cats and dogs have very different nutritional needs and it’s not advisable to feed the food meant for one species to another. This is especially the case with cats, who are obligate carnivores and need to be supplied with nutrients found in meat products. This also means that prescription diets vary between cats and dogs, and between medical conditions. It is important to feed the correct diet for your pet’s health.

What should I ask a vet about prescription diets?

If you are worried about your pet’s health, it is worth booking a vet appointment, so that they can have a health check and you can discuss your concerns. During the appointment, you can ask the vet about whether a therapeutic diet is available that would be appropriate for your pet and whether this is necessary.

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