Food intolerance in cats

Food intolerance is when a cat’s body is unable to cope with something they’ve eaten and they become ill. This is a common problem and may happen for different reasons. In rare cases, it can be serious, but more commonly, it’s a long-term problem that stops if the problematic food is no longer given.

Food intolerance can happen to any cat. It is different from food allergy because the immune system isn’t involved. It can be difficult to tell them apart though. Cats can become intolerant to something they’ve eaten for a long time, but it can also happen the first time they eat something new. Usually the symptoms are a digestive upset, but skin reactions are also common. Diagnosis is usually done with a strict diet for several weeks.



What is food intolerance in cats?

There are several causes of food intolerance:

  • Deficiencies in digesting or using certain foods, such as lactose intolerance.
  • Metabolic problems that lead to abnormal storage of the components of food in the body. This can lead to problems such as liver disease caused by copper accumulation
  • Medication-like effects, such as histamine present in fish that is not fresh, cause allergic-type reactions
  • Abnormal reactions to ingredients in the food
  • Spoiled foods
  • When toxic substances are present in the food

Most often the end result is that food won’t be digested properly, but other parts of the body may also be affected, with the skin being the most common.



Symptoms of food intolerance in cats

Food intolerance can have a range of symptoms. Some of the more common ones are:



Cats at higher risk of food intolerance

Food intolerance can affect cats of any age and sometimes develops after a cat has been eating a food for years. It does seem to develop more often when cats are still young (under 5 years). Siamese cats seem to be more prone to food intolerance.



Diagnosis of food intolerance in cats

Food intolerance is usually suspected based on the symptoms. Tests may be needed to rule out other diseases:

  • Faeces tests to rule out intestinal parasites and some infections
  • Blood tests to rule out diseases of internal organs, such as pancreatitis or liver disease
  • Skin scrapes to rule out mites

The final diagnosis of food intolerance is usually achieved by doing a strict diet with a special food for 6-8 weeks.


Vet treatment

Vet treatment of food intolerance in cats

If symptoms are serious, your pet will need to see a vet. Depending on what is found, the vet may recommend:

  • Intravenous fluids (a drip) to correct dehydration and electrolyte imbalances
  • Anti-vomiting medication
  • Antacids to help the stomach heal
  • Medication to reduce itching, such as steroids
  • Pain medication when necessary
  • Skin products to soothe the skin and restore the skin’s defences
  • Some types of infections may be treated with antibiotics


Home treatment

Home treatment of food intolerance in cats

Avoiding problematic foods is obviously the goal of treating food intolerance. If your cat has managed to eat something they are intolerant of and has developed serious symptoms, speak to a vet (see below). If the symptoms are mild, or once they have improved with treatment at the vet, a few things can be done at home to help with recovery.

  • If vomiting has been a problem, a short period (4-12 hours, depending on age and other factors) on an empty stomach may help things settle.
  • Small, frequent meals and an easy to digest diet for a few days will feed the healing of the gut while reducing the symptoms. Chicken and white fish can help in many cases if your cat is not intolerant of them. Special foods are available to boost the healing of the gut, such as Hill’s I/D or Z/D.
  • Anti-diarrhoea pastes contain special minerals (for example, kaolin or montmorillonite) that firm up the stool and help reduce the symptoms.
  • Good bacteria (probiotics) and their food (prebiotics) will help the gut function return to normal.
  • Skin products are available to help with itchy or irritated skin, but the best product to use will depend on the situation. Speak to a vet for further advice.



Can food intolerance in cats be prevented?

There is no known way to prevent the development of food intolerance.


When to worry

When to worry about food intolerance in cats

Take your cat to see a vet immediately if they show:

  • Large amounts of blood in their diarrhoea
  • Black or tarry stools
  • Constant vomiting
  • Weakness or lack of response when you interact with them
  • Severe swelling of the face
  • Wheezing or laboured breath

Speak to a vet as soon as possible if your cat:

  • Continues to vomit even on an empty stomach
  • Is constantly passing watery diarrhoea
  • Loses interest in food
  • Is quiet or lethargic
  • Passes blood in their diarrhoea
  • Has puffy eyes or swollen face
  • Is itching constantly or has broken skin
  • Has a sore lump on their lips, thighs or other areas.

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