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There are two common reasons
for dogs to be very itchy - mite infestation (called Scabies), and allergic
skin reactions (also called eczema, summer eczema, dermatitis, allergic
dermatitis). Mites are often difficult to diagnose, and may require a
trial treatment to eliminate it as a possibility. Depending on things
like possible exposure, areas of itchiness, skin scrapings and response
to treatments, we will be able to advise you if this is necessary. Signs
of allergies include chewing at skin, licking excessively, rubbing against
objects and on the ground, scooting (rubbing bottom along the ground),
chewing/licking at feet, chronic ear irritation, chronic watery eyes or,
occasionally, sneezing. There are other problems that can cause each of
these, so it is important to have the vet assess the problem at least
initially.
We can divide skin allergies
into 5 general areas:
-
Flea
Allergies - usually chewing/scratching around tail base or around neck, but can be itchy anywhere. Unfortunately it takes only 1 flea to cause a flea allergy, which is why some dogs that have very few fleas can be itchier than a dog with many fleas that isn't allergic. Often seasonal (Spring/Summer), but can be all year round.
-
Food
Allergies - often will be itchy around the face, ears and feet, although can be itchy all over. Most common allergens include wheat products (found in most canned and dry foods), beef, and to a lesser degree chicken. Allergies will occur all year round.
-
Contact
Allergies - are quite uncommon, and usually affect areas with no or little fur cover eg. abdomen and feet. Allergens include grasses, plants, clothing/carpet fibres and many others. Often seasonal, but can be all year round. Most common is
wandering
jew.
-
Inhaled
Allergies - are quite common, and commonly affect all areas ie. skin, feet, ears, face, eye, nose etc.. Most common allergens include grass pollens, other plant pollens, dust mites, and moulds (found normally in most environments). Often seasonal, but can be all year round.
-
Allergies to the normal bacteria found on the
skin - called Staph. Allergies (Staphylococcus being the most common skin bacteria). These will often show slightly different signs to other allergies- your vet will be able to determine if this is a likely possibility. Often all year round.
Despite these guidelines,
all allergies can cause itchiness anywhere, so it is impossible to tell
just on appearances which allergen is causing the problem. While the allergens
mentioned above are the most common causes of allergies, there are literally
hundreds of substances that can cause allergies. Similarly, many allergic
dog are allergic to several allergens, so, for example, eliminating fleas
will solve a flea allergy problem, if the dog is also allergic to grasses,
we have only solved half of the problem.
So where do we start!!
There are 2 main options when trying to deal with allergies:-
(1)
Discovering the Cause
two types of allergies that can be eliminated without medications or expensive testing are flea allergies and food allergies.
(a)
If fleas are present, it is worthwhile trying to eliminate them. Unfortunately, where allergies are concerned, we need to eliminate all fleas from the environment. We can give you advice on the best flea medications for your situation.
(b)
If a food allergy is suspected, the dog can be trialed on a low allergy food diet. This involves maintaining the diet for at least 6 weeks, and having no breaks from a strict list of foods that can be used eg. having a single dog biscuit at week 4 can ruin a trial in a dog allergic to wheat. This is difficult, but does help greatly if we can implicate or eliminate food as a cause.
The diet consists of:-
(i)
Meat that the dog hasn't had before eg. fish, kangaroo, rabbit, lamb. This should make up about 30% of the meal.
(ii)
Rice -
boiled - approx. 50% of meal.
(iii) Vegetables
- approx. 20% of meal.
After 6 weeks, we can often get a 'yes or no' as to the possibility of food allergies.
- if it has been determined that food and fleas aren't implicated, an allergy test can be
performed. This is a test for inhaled allergens, and tests 30-40 of the most common allergens, including plants, grasses, trees, dust mites and moulds. This is done by taking blood- the test takes approximately 2 days to perform. If these results suggest an allergen that cannot be avoided (eg. dust mites), then a vaccine can be made up against these allergens, and given as a series of injections. Very rarely are side effects seen with this treatment, and results can be favourable.
- if all of the above has been performed to no avail, then a contact allergy, or inhaled allergen not included in the allergy test is most likely. Further trials can be performed at home eg. change bedding, send dog to a relatives place for 3-4 weeks. If no allergen can be identified, option (2) is taken.
(2)
Trialing medications -
Cortisone is often used to control allergies because it is the only medication that will nearly always stop itching quickly and effectively. This makes it a very good short term solution. However, due to the side-effects it can have if used constantly (called Cushings Syndrome- thinning of skin, liver problems, weight gain, predisposing to infections, diabetes, hair loss, lethargy and increased thirst), CORTISONE IS NOT A GOOD LONG TERM SOLUTION. Unfortunately, this means we have to find something else to solve the problem. There are many things that sometimes help, and trying them by themselves or in combination can be worthwhile. These include:-
(a)
Anti-histamines - the main side-effect from anti-histamines is drowsiness. This is uncommon, and can be remedied by decreasing the dose. Anti-histamines work better with evening primrose oil (see below) than alone. Some anti-histamines to try include:-
Please contact us for the appropriate dose for your dog.
For each dog, one anti-histamine may work, when another won't, so trialing several is helpful. All of these medications can be bought from any chemist without prescription.
(b)
Evening Primrose Oil - use daily at 1-4 capsules in food. The capsules can be broken, and the oil applied to food. A less expensive version is available from us.
(c) Anti-allergy shampoos and
conditioners - from us or pet shops.
There are many other washes etc. that people have reported to us to have helped, eg. tea tree preparations, and eucalyptus rinses. While these can also be tried, we have had rare allergic reactions reported. There are also other medications that we can dispense, that will sometimes help.
Penrith Veterinary Hospital
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