1. The best treatment is to determine the cause of the allergy and avoid it. As this is not always possible, various control measures are taken to relieve the itching and allow your pet to live comfortably. Allergy testing may be performed by skin testing or blood testing. Testing is performed to determine the allergic cause and to develop a vaccine administered on a regular basis to stimulate your pet's immune system to fight the allergens. Allergy treatment by injections may take one year to see results and is moderately successful.

2. Symptomatic treatments include antihistamines, steroids, medicated shampoos, and
omega-3 fatty acids.

3. Some pets require continual treatment.

4. Regular bathing and grooming may be necessary to remove allergens from the coat and maintain a healthy coat.

Flea Allergy
Flea allergic dermatitis is the most common skin disease in dogs and cats. For the flea allergic patient, 100% flea control is essential for the pet to remain symptom-free. This allergy is caused by the flea's saliva, and it only takes a few bites to induce the problem. In warm climates or in our homes, fleas may survive in low numbers year-round. Because flea allergy is so common, we recommend that complete flea control be instituted before proceeding with diagnostics for other allergies and that year-round flea control be maintained for all allergy patients. Flea allergies routinely cause hair loss at the lower back area (called the dorsal-lumbar area), which is not typical of atopy and food allergy. Flea allergy dermatitis does not cause hair loss around the face, eyes, and ears like in atopy.

Fleas or flea dirt can be detected using a flea comb. Flea dirt is droppings from the flea after is has bitten a pet and the blood has passed through the flea's digestive tract. It looks like pepper, and is easily visualized on a pet with a white haircoat.

Flea dirt visible on a patient’s haircoat

Magnified flea causing visible irritation to the skin

Food Allergy
Some pets develop specific hypersensitivities to components of their diets. The allergen usually is a major protein or carbohydrate ingredient such as beef, chicken, pork, corn, wheat, or soy. Minor ingredients such as preservatives or dyes are also potential allergens. In dogs, beef, dairy products, and wheat tend to cause most of the problems, with chicken, lamb, and soy following. In cats, beef, dairy products, and fish account for most of the food allergies. Premium dog foods can contain these products, so just because you are feeing a higher quality or more expensive food doesn't mean that food will not cause a food allergy.

The diagnosis of food allergy requires that we test your pet by feeding special strict diets that contain only ingredients that he has never eaten before. This is often achieved by feeding a prescription diet for a period of 10 to 16 weeks. If the signs resolve, a challenge is performed by feeding the former diet and watching for a return of the itching. If this occurs, a diagnosis of food allergy is confirmed.


Fortunately, many pet food companies have discerned the need for diets using unusual protein and carbohydrate sources with a minimum of additives. Foods can be obtained based on venision and potato, fish and potato, egg and rice, duck and pea, and even kangaroo. Many of these specialized diets are available both as canned and dry formulas. Some examples of allergy diets include Hill’s Science Diet d/d, Royal Canin (IVD) allergy diet, and Eukanuba Response FP.

It is important that during the diet trial no unnecessary medications be given. No edible chew toys (such as rawhides or bones) should be given. Treats must be based on the same food sources as the test diet. Chewable heartworm preventives should be replaced with tablets.

Recently a new approach has been introduced using diets made from hydrolyzed proteins. This means that a conventional protein source is used but the protein is broken down into molecules too small to excite the immune system. There are two such diets currently marketed: Hill's(TM) Z/D and Ultra Z/D

How Long to Feed the Trial Diet
Some food allergic animals require 8 to 10 weeks to respond. Our current recommendation calls for a recheck appointment or phone call after four weeks of diet trial and then again after eight weeks of trial. Eighty percent of food allergic dogs will have responded to diet trial at least partially by six weeks. The Labrador retriever and cocker spaniel appear to require up 10 weeks of trial diet before showing a response. Some animals may even require a longer period.

What to Do if the Diet is Successful?
To confirm food allergy, return to the original food. If itching resumes within 14 days, a food allergy was most likely the reason for the itchy skin. Many people do not want to take a chance of returning to itching if the patient is doing well; it is not unreasonable to simply stay with the test diet if the pet remains free of symptoms.

It is possible to more specifically determine the identity of the offending foods after the pet is well. To do this, a pure protein source (such as cooked chicken, tofu, wheat flour or any other single food) is added to the test diet with each feeding. If the pet begins to itch within 2 weeks, then that protein source represents one of the pet's allergens. Return to the test diet until the itching stops and try another pure protein source. If no itching results after two weeks of feeding a test protein, the pet is not allergic to this protein.

What to Do if the Diet is Unsuccessful?
Generally, an unsuccessful food trial is strongly suggestive that an inhalant allergy is the primary problem, but there are some other possibilities that should be considered:

• Are you certain that the dog received no other food or substances orally during the trial?
• Was sarcoptic mange ruled out?
• Your pet may require a longer diet trial.
• Has your pet ever had a skin culture or biopsy? Now may be a good time.

If an inhalant allergy is being considered, symptomatic relief either via medication, medicated baths, or allergy shots may be necessary. Chronic itchiness can be extremely uncomfortable and prompt relief is the goal.

Allergies are often the underlying cause of recurring skin and/or ear infections. Bacterial and yeast infections, though secondary to the allergy, can cause an increase in your pet's level of itching. Long-term treatment with antibiotics and anti-yeast medications is commonly required along with medicated bathing programs.

It is an area of skin that has been maimed from intense pruritis. Pyoderma is also present, and the skin is very painful. Hot spots occur rapidly and can encompass a large section of skin in a short time. Affected areas usually include the rump and the side of the face. Other common causes of hot spots include anal gland problems, ectoparasites like mange, grooming, and deep skin infections. Golden and Labrador retrievers, St. Bernards, Collies, and German shepherds are more prone than other breeds.

There are many causes, allergies being a primary one. Other causes include arthritis, skin tumors, inflamed nerves, fungal infections, ectoparasites, and psychological factors like boredom and stress. Once the licking starts the problem is difficult to control. In some cases we have found that the use of the laser has been a significant help.

A small lick granuloma on the front
leg of a Golden Retriever

Diagnostic Tests to Rule-Out Allergy

Skin Scraping
It is important to do a skin scraping in many cases of allergy because atopic lesions commonly mimic those of other diseases. Ectoparasites like demodex or scabies can cause skin lesions and itching.

Fungal Tests
Ringworm can mimic allergy symptoms. However, lesions from Ringworm tend not to be as pruritic as allergies. Ringworm is diagnosed by swabbing the affected area. This sample is plated in a culture medium to determine if there is any fungal growth over a period of time.


Malassezia, another fungus, is commonly associated as a secondary problem when the skin is infected. Even though it is a normal part of an animal’s haircoat, it will add to the itching if other conditions are present. Common areas for Malassezia include the ears, lips, muzzle, between the toes, and the anal area. Indications that Malassezia is present include pruritis, erythema, and greasy skin with an offensive odor.


Malassezia is diagnosed by the above symptoms and by microscopic examination of skin discharge obtained by swabbing the skin. Many pets respond to medicated baths with specific antifungal shampoos twice weekly. These topical treatments will only work when the underlying allergy and its associated skin infection are under control. In some cases, it is necessary to prescribe oral antifungal medications.

Thyroid Test
A blood test can be done to determine if a pet has a thyroid imbalance. Hypothyroidism can cause skin conditions including hair loss, although dogs with only hypothyroidism are not excessively pruritic.

Routine Blood Panels
On occasion a specific type of white blood cell, called an eosinophil, is elevated in allergic conditions. Other conditions, like internal parasites, can also cause this elevation. A routine blood panel can also give an indication of internal or hormonal problems that might show up as a skin condition. The most important of these is Cushing's Disease.

Skin Biopsy
In some cases it is difficult to make a diagnosis. When there is no definitive diagnosis, a veterinarian may biopsy several small pieces of infected skin and have them analyzed by a pathologist. The cytology results may tell us the cause of the skin disorder.

Diagnostic Allergy Tests

Allergy tests are performed in cases where we already have a diagnosis of allergy. The main purpose of allergy testing is to find exactly what your pet is allergic to, and also to set up a protocol for allergy injections. Allergy tests will let us know what allergens we want to avoid.

There are two main types of allergy tests that are performed. Neither one is perfect, and they can have false positives and false negatives.


In this test, called the ‘allergy skin test’ or ‘intradermal test’, small amounts of materials that routinely cause allergies in dogs are injected under the skin. The reaction, if any, is graded, and a determination is made as to whether or not a pet is allergic to that specific allergen.

Your pet must not take oral cortisone medication for at least 1 month before testing. If injectable cortisone is given, the waiting time is longer. Your pet must not take tranquilizers at the time of testing and not use antihistamine medication for 10 days.

Pets usually are given a sedative to calm them and to minimize the release of cortisone due to stress, which will affect the outcome. The hair on the side is clipped where there is no current dermatitis. A tiny amount of histamine is injected first. If there is no reaction to histamine, the full test is postponed. A small amount of sterile saline is also injected as a control.

The areas where the allergen is injected are marked

Numerous allergens are injected into the skin and a reaction is noted at 15 minutes and again at 30 minutes. The reaction we are looking for is called a wheal. A positive test to a specific allergen occurs when the reaction is in between the saline and histamine tests in size.

In some cases the wheal is obvious, in others it is subtle, which is part of the interpretation process.




The second type of test that is performed is called the RAST test. RAST stands for radioallergosorbent test. It tests for the levels of allergen specific IgE. In this test, a blood sample is taken and submitted to a special lab for analysis.

The RAST test has advantages over the intradermal test. There is no clipping, sedating, and there is no potential to have an adverse reaction to an allergen injected into the skin. There is less of a chance that prior drug therapy (cortisone) will influence the outcome, and it can be used in patients that have dermatitis.

The primary disadvantage is the fact that false positives are more common when compared to the intradermal test.The RAST test is very thorough and checks for many different allergens in the home, outside, and in your pet's food.


Allergy tests can be unreliable at diagnosing food allergy. A better way to diagnose food allergies is using a technique called the elimination trial. By taking away a food that is suspected of causing the food allergy you can determine if the problem resolves. This might take up to several months to know for sure. To verify the diagnosis you need to feed the suspected food again to see if the skin condition returns. Commercial diets that contain rice, venison, fish, and potato are commonly used for the elimination trial.

Treatment

In the early years of atopic dermatitis, the pruritis is more easily controlled. As the problem progresses treatment is less effective. Chronic changes to the skin can occur, especially lichenification (thickening and hardening of the skin) and hyperpigmentation (increased darkness of skin color).

Treatment is aimed at all the factors that contribute to pruritis. For example, a pet that is normally not itchy might become so if exposed to fleas or if it gets a pyoderma. These multiple factors must be taken into account when developing a treatment protocol.

Avoidance
If it is exposure to an allergen that causes the problem in the first place, then we should try to eliminate this exposure. In reality though, these allergens are everywhere. Minimizing exposure can be beneficial since it will decrease the allergen load, and hopefully keep your pet from experiencing the symptoms associated with skin disorders.

Pets that are allergic to kapok, wool, cotton, feathers, animal dander, newspaper, and tobacco smoke all might benefit from limiting exposure. Limiting the number of houseplants could be helpful, and the use of synthetic material for your pets’ bedding. Pets allergic to house dust mites might experience less allergies if kept out of bedrooms or placed outside more often. Being outside though might expose them to more pollens. Keep the grass cut short, and keep pets out of the yard when cutting the grass. Rinsing your pet's feet and face off thoroughly after being outside can be beneficial in some cases.

Mold allergies might be helped by dusting and cleaning more thoroughly, especially house plants and bathroom carpets. Keep your pet away from damp areas like basements and use humidifiers and air conditioners in humid weather. Rinse the filters frequently and clean with chlorine bleach. To truly filter most of the dust, mites, pollens, bacteria, and molds in your house you need to use a HEPA (high efficiency particulate air) filter. Upright vacuum cleaners return most of the dust back into the air, so use canister or cylindrical type machines.

Routine and thorough washing, cleaning, and vacuuming of your household will keep mold, house dust, and house dust mites to a minimum. Keep your pet out of the house when doing thorough cleaning and vacuuming to minimize allergens that are stirred up by the cleaning. Put plastic over bedding that might harbor house dust. Keep pets indoors at dusk and early morning during heavy pollen seasons.


Flea Control
Since we live in a flea endemic area year round, it is incredibly important to use proper flea control year round in any pet that has a skin condition. Even pets that are 100% indoors are susceptible to flea bites.

The products available today are a significant improvement over flea control products in the recent past. They are economical, safe, effective, and very convenient. The main products we recommend are Advantage© and Frontline Plus©. Revolution© is another available product that kills fleas and treats heartworm, ear mites, and internal parasites.



Anti-inflammatories

Cortisone
One of the primary oral medications for treating atopy is cortisone, commonly know as steroids. These steroids fit in the class of drugs called corticosteroids. Cortisone use is usually reserved for flare-ups, since long term use has the potential for causing side effects. Long term use of high doses of cortisone can lead to hair loss, thinning of the skin, liver problems, stomach problems, and muscle weakness. The overuse of cortisone can also cause iatrogenic Cushing's disease (excessive pituitary excretion of adrenocorticotropic hormone).

Cats are more resistant to the side effects of cortisone than dogs. Some cats are difficult to give oral medication, so it is not uncommon to use an injectable version of cortisone that lasts for several months. Older cats need to be checked for underlying problems like diabetes before instituting cortisone therapy. Cortisone will raise the blood sugar level, making it more difficult to control the problem.

Cortisone is usually given on an every other day basis. This minimizes side effects yet still gives an adequate amount of the drug to minimize scratching. In many cases we give an injection first to give your pet immediate relief from the scratching. We may use cortisone for 1-2 weeks to help get the scratching problem under control.

While on cortisone you will notice that your pet drinks and urinates more than usual. It might also have an increased appetite and might show some behavioral changes. These symptoms will go away, in the meantime make sure your pet has access to fresh water at all times and can go outside to use the bathroom frequently.

Antihistamines

Antihistamines can be effective in treatment in some skin allergies. They counteract the release of histamine from the mast cell, the source of the itching. Antihistamines are the mainstay of our long term medical treatment for skin allergies. Occasional side effects include drowsiness and dry mouth, both of which tend to resolve. In general, they are safe to use on a long term basis.

Your veterinarian may start an antihistamine trial to determine which one, if any, is most effective for your pet. The trial lasts for up to 2 weeks to determine if a particular antihistamine is effective. It is a good idea to stop cortisone use at the same time your pet is trying a new antihistamine, since your veterinarian will not know if a decrease in pruritis is due the cortisone or the antihistamine. If one antihistamine works effectively, your pet will be taking that antihistamine on a long term basis. Eventually this might change, and if there is a significant flare up, cortisone is used to control the problem for several weeks. In the long run, even if antihistamine use has only minimal effects on decreasing pruritis, its use can help us decrease the use of cortisone.

Some of the common antihistamines we use are:

• Benadryl
• Atarax
• Tavist
• Chlorphenaramine
• Amitryptiline

Antibiotics

Some dogs scratch so severely they cause a secondary bacterial infection of the skin called pyoderma. The bacteria that commonly cause pyoderma are called Staphylococcus intermedius. This secondary bacterial infection intensifies the itching. These dogs need treatment with antibiotics for several weeks to several months. In addition, they need to be bathed with medicated shampoo that will help the skin infection. Long term use of antihistamines are not effective if a skin infection is allowed to persist.

The area of pyoderma is often called a ‘hot spot.’ If a hot spot is present it will be gently clipped and cleansed with an antiseptic like Betadyne. Pets with hot spots must be put on antibiotics and usually short term cortisone to prevent the problem from progressing. A topical corticosteroid spray like Betagen or Gentamycin may be prescribed to decrease inflammation and irritation. These hot spots are very uncomfortable for pets and can expand in size and severity very quickly.

Antibiotics that work best for pyoderma include:

• Cephalexin
• Baytril
• Clavamox

Antifungals

Secondary fungal infections can occur, especially when the feet are licked frequently. The most common fungal infection is called Malassezia. It is treated with topical antifungals (ketoconazole) and medicated baths in most cases. West Highland Terriers, Poodles, Basset Hounds, Cocker Spaniels, and Dachshunds are more prone to this yeast infection.


Cyclosporines
A relatively new treatment for atopy relies on cyclosporines, the medication that prevents organ transplant rejections. It is called Atopica©

Atopica© is used to replace cortisone in dogs only. Your dog must weigh at least 4 pounds for use. Its main advantage is that it has few side effects and can be used on a long term basis. It can be highly effective, but can cause short-term vomiting and diarrhea. Initially it is given once daily for 30 days, and should be given one hour prior or two hours after a meal. If a response is achieved, the dose will be decreased slowly, with the ultimate goal of giving it twice per week. It is probably worthwhile to try this medication if your dog is on chronic cortisone use.

Allergy Shots
If an allergy test is performed on your pet, we will know what it is allergic to. Then allergy shots can be custom designed for your pet’s specific allergies. Giving allergy shots is called hyposensitization or immunotherapy. Theoretically, hyposensitization stimulates the production of IgG, which subsequently attaches to the allergen, preventing IgE from attaching to this same allergen. If there is no IgE attached to the allergen, then the mast cells do not release histamine and no allergic reaction is produced.

Even if you do not give the allergy shots, knowing what your pet is allergic to can be beneficial because you can remove the offending allergen from your pet’s environment. Allergy shots are used when avoidance methods and medication are unsatisfactory in minimizing pruritis.

Giving allergy shots can be a significant way to minimize your pets scratching, although just like in people, no guarantee can be given. In general with allergy shots, you can expect some improvement 60% of the time. In some cases we will still keep your pet on an antihistamine, cortisone or Atopica© at a reduced dose. A decision to undertake this treatment modality takes a commitment to a lifetime of giving these injections.

Giving the injection is very easy since a small amount of serum is injected with a tiny needle. We will teach you how to give these allergy injections, and if need be, will give them for you. Initially, the injections are given every few days for several months. It takes several months to know if the allergy injections are working, and up to a year for full effectiveness. Eventually, these injections are given once every few weeks to a few months per year. Each pet's response is different.

Allergens are made specifically
for each pet

Room Purifier
If your pet is kept in a confined area, the use of a room purifier that filters out pollen particles can help with allergies.


Food Supplements
Some allergic dogs and cats scratch less when supplemented with essential fatty acids. Some examples of these are Derm Caps, 3V Caps, and EFA-Z. As with other therapeutic options, essential fatty acids will not be effective if your pet has pyoderma. It will take at least several weeks of supplementation to see an improvement in your pet’s skin condition. In some cases, the need for inflammatory medication may be reduced when a pet is taking essential fatty acids supplementation.



Medicated Baths

Bathing in cool water several times per week is beneficial. Do not use hot water because it can intensify the itching. Proper bathing will help remove allergens and eliminate dry skin, both factors that affect the pruritic threshold. However, bathing your pet too often can dry its skin out and increase its itchiness.

We have a number of medicated shampoos and rinses to help your pet’s skin condition, including Relief, Chlorhexiderm, Malaseb, and Oatmeal shampoos. For hot spots we use Malaseb shampoo. If we suspect a secondary fungal infection caused by Malassezia we will use an antifungal shampoo called Chlorhexiderm. We also carry shampoos for seborrhea skin conditions (moist, oily, scaly skin).

Topical Medications

There is a strong tendency on the part of pet owners to use topical medications for allergic skin disease. They are prescribed by veterinarians and are helpful, but should not be relied upon as the primary source of treatment. Topical medications we use usually have an antibiotic, antihistamine, or cortisone base. We use topical agents most often with pets with hot spots. In these cases we use a topical spray in addition to oral antibiotics for complete treatment.

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