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Adverse food
reactions may be the result of food allergies or food intolerance.
Clinical signs will be more severe in cats that have existing
gastrointestinal disease. Some cats have severe reactions when exposed
to trace amounts of the offending food. In other cats clinical signs
may not appear until the cat is exposed to more than one antigen.
The reactions may be dermatologic, gastrointestinal or both systems
may affected. Some of the dermatologic signs seen are: scratching of
the head and neck, non-inflamed hairless skin, and moist or scaling
dermatitis. Over one third of the cats with skin lesions related to
adverse food reactions also suffer from flea allergy and or inhalant
allergies. The gastrointestinal signs that may be seen include
vomiting (hours to minutes after eating), diarrhea and flatulence.
The signs associated with adverse food
reactions are not specific for this condition. Testing and therapeutic
trials are needed to make this diagnosis.
Flea control and deworming
are the first interventions needed for these patients. Flea allergies
can produce identical dermatologic signs to food allergy and can make
the clinical signs of food allergy much worse. The monthly application
of a flea control product is an essential part of diagnosis and
treatment of adverse food reactions. Intestinal parasites can
produce
identical gastrointestinal signs (vomiting, diarrhea, flatulence)
to those seen with adverse food reactions. Strategic deworming should
be part of every patient’s treatment.
Following these interventions
the following tests are used to rule out other causes of hair loss and
gastrointestinal signs:
There is not a
specific blood test for food allergy. Elimination diets are essential
to reach a diagnosis. These may be homemade with a single protein
source (rabbit, venison etc.), commercial foods that have a single
protein source or a hydrolyzed diet that contains smaller molecules
that are unlikely to cause an adverse food reaction. The commercial
diets that are used at The Cat Clinic of Stillwater are:
Hills D/D (venison
and pea) dry and canned Royal Canin limited antigen diet
(venison and pea) dry and canned, and Hills Z/ D (a hydrolyzed diet)
A diet is selected
based on the patient’s acceptance. Gradual change from the cat’s
current diet to new diet may be needed and it may take some cats
several weeks to make the change. In multi-cat households, the
affected cat may be fed separately or all cats may be fed the new
diet. Outdoor cats will need to be kept inside during the trial to
assure only the limited antigen diet is consumed. Once the diet is
selected, it must be the only diet consumed for 6 to 8 weeks.
Studies have shown that 2/3 of these patients will show improvement on
appropriate commercial foods. Partial and complete remissions may be
seen.
The diagnosis and
treatment of adverse food reactions is challenging and time consuming.
Successful treatment markedly improves the quality of life for the
patient and the caregiver.
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