An adverse reaction to food most frequently affects
the skin or digestive system. This is why skin and intestinal disease
in their various forms are probably the commonest problems seen
by veterinary surgeons.
In the dog this can vary from a low-grade itchiness,
which many owners accept as normal for a dog to severe widespread
inflammation with reddening, blisters, eruptions, weeping clear
fluid or pus. The appearance, frequency and distribution of lesions
(areas of damage) varies tremendously. In most dogs self-mutilation
by scratching, licking, chewing and biting serve to aggravate the
The cat tends to produce less dramatic symptoms.
Scratching tends to be less but the cat will groom excessively.
As the condition progresses the cat will become moth-eaten in appearance
as bald patches appear. There will often be numerous tiny dry scabs
all over the skin (known as military eczema).
Skin irritation tends to recur and become persistent
and difficult to treat although some dogs tend to be affected only
seasonally. Occasionally the problem will surface when the bitch
comes in to season or has puppies. Some breeds are affected more
than others (West Highland Terriers seem particularly prone) so
there is clearly some genetic susceptibility.
Diagnosis of skin problems can be extremely complicated
and a mini-industry funded by pet insurance companies has grown
in recent years. Dogs are frequently found to be "allergic"
to many different outside factors such as fleas, house dust mites,
wool, carpets, synthetic furnishings, cleaning materials, chemicals
in the diet, foodstuffs. Veterinary immunologists insist however
that true food allergy is present in less than 10 % of dogs that
Many "allergies" are due to food intolerance
rather than true allergy, the difference being that an allergy is
characterised by involvement of the immune system whereas an intolerance
is not. The clinical symptoms are the same.
Treatment of skin irritation usually takes the form
of anti-inflammatory drugs (steroids), antibiotics, de-sensitising
regimes using vaccines tailored specifically to the individual dog.
None of these approaches is likely to prove rewarding
because they fail to tackle the true, underlying cause of the problem
which is the build-up of toxins in the dog's system. It is often
impossible to avoid the dog encountering those things to which it
is allergic (grass, house dust etc.) but it is possible to treat
the dog by changing the dog's system so that it does not over-react
to its normal environment.
Many cases of skin disease are due to an undiagnosed
adverse reaction to food ingredients and a change of diet which
eliminates the offending ingredients will be effective.
Essential fatty acids (EFA) are important for maintaining
healthy skin and there are many preparations on the market which
are high in EFA’s e.g. Evening Primrose Oil, fish oils etc.
These will be useful to supplement a diet which is deficient in
EFA but a properly formulated diet will have adequate levels.
Common pet health problems
John Burns Pet Health Management