# Allergies



## MSK (Aug 13, 2008)

Subject: Allergies.... Sat 31 May 2008 - 11:19
Allergies are one of the most common causes of skin conditions. They are encountered in pets, especially dogs, as often as we see them in humanoids. The main difference between us and pets is that allergies in pets tend to cause skin conditions.

It goes by several names, the most common are atopy, allergic skin disease, or allergic inhalant dermatitis.

Allergies can be hard to control and are chronic in nature. This causes significant frustration for pet owners and discomfort for pets. A correct diagnosis along with proper therapy instituted early in the course of the disease will minimize this frustration.

This page summarizes and generalizes the complex problem know as allergic skin disease. It is detailed, and will take a few minutes of your undivided attention to help in understanding this problem.

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Pathophysiology of Allergies

When the immune system encounters an allergen that has the potential to cause disease (ex. parvo virus) it produces antibodies called IgG (immunoglobulin G, previously known as gammaglobulin) and IgM (immunoglobulin M). For the first 7-14 days of infection the virus spreads throughout the body because not enough antibodies are produced to stop them. Within 7-14 days enough antibodies are made to neutralize the virus, and the dog eventually recovers from the disease, all other things being equal.

As time goes on the now sensitized immune system is ready to produce large amounts of antibodies rapidly the next time it encounters this virus. The rapid antibody response neutralizes the virus immediately, instead of taking the 7-14 days that occurs the first time it encountered the virus. This is called the anamnestic response, and is why a dog that recovers from parvo virus does not get the disease again.

A different scenario presents itself when the immune system encounters an allergen that is not necessarily pathogenic (ex.- a pollen particle). A different part of the immune system kicks into high gear when these nonpathogenic allergens invade the body.

When a pollen particle enters the body for the first time (through the skin or respiratory passage) it stimulates the body to produce antibodies also, this time they are called IgE (immunoglobulin E). This IgE antibody attaches to the allergen in order to neutralize it, just like IgG would do to a parvo virus. This process, called sensitization, occurs in the first season a pet encounters a specific allergen in its area. Without this sensitization there is no allergy.

The next time a pet encounters these pollen particles (usually the next allergy season) the immune system produces large amounts of IgE antibodies rapidly because it has been sensitized to them from the previous season. Again, this is similar to what happens when the immune system makes IgG and IgM antibodies against parvo virus.

IgE, with attached allergens, circulates throughout the bloodstream to a type of cell called the mast cell. Mast cells contain many chemicals that can cause inflammation, the most important of which in relation to allergies is called histamine. When an IgE antibody (even IgG can be involved)) with an attached allergen encounters a mast cell in the skin, it alters the membrane of the cell, and histamine leaks into the surrounding tissue. Histamine causes inflammation, noted as redness (erythema) and itching (pruritis) on the skin surface. The reaction that is seen on the skin surfaceis called a wheal or a hive.

It is the mast cell, that releases histamine when it encounters an IgE antibody with a pollen particle attached, that is a major component of allergies. This is what occurs in atopy and is suspected to occur in food allergy. In flea allergies, it is an allergic reaction to the flea saliva that causes the immune system reaction.

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Types

There are 3 main types of allergies in relation to skin conditions. It is possible for a pet to have a combination of all 3 allergy types:

1. Food Allergy

They are caused by an allergic reaction to ingredients or preservatives in food. Some of the more common food allergens are:

horse meat, eggs, beef, fish, pork, corn, lamb, soy, poultry products, preservatives and dyes, dairy products, rawhide chews and dog biscuits/treats


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 dogs 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.

Dog owners commonly go to pet stores to get food to stop their pet from scratching. Pet store employees will recommend a specific food to stop the itching because they are under the assumption that this is the main type of allergy that causes skin conditions in pets. Unfortunately, by a large margin, food allergies are the least common of the allergic skin problems we diagnose.

It is estimated by some veterinary dermatologists that food allergies account for only 10% of all the allergies that cause allergic dermatitis. In those pets that truly have food allergy, a high percentage also have atopy at the same time. Cats might have more food allergies than dogs.

2. Flea Allergy Dermatitis (FAD)

When a flea bites a dog or cat it is looking for a meal of blood in which to nourish itself. In order to suck this blood it inserts an anticoagulant into its saliva to prevent the blood from clotting while it sucks it through its small proboscis. It is the allergens in this saliva that cause an allergic reaction to occur.

Until the recent past FAD was a very common cause of allergic dermatitis. With the advent of new treatments that are convenient and very effective, this problem, while still important, has diminished in importance. The products we recommend are Revolution, Advantage, and Frontline.

3. Atopy or Allergic Inhaled Dermatitis

Canine atopy is a genetically determined predisposition to produce IgE antibodies when exposed to an allergen. Re-exposure to this same allergen in the future causes allergic skin disease (you learned the mechanism above). Depending on the study, it is estimated that between 3% and 15% of dogs have atopy.

Common allergens that cause this reaction are ragweed, pollen, house dust, house dust mites, mold, animal dander, feathers, grasses, trees, and shrubs. The allergens can be inhaled, pass through the pads of the feet, and even possibly ingested. Since these compounds are in abundance everywhere, it is apparent that preventing exposure in the first place is impossible.

If fleas are not a factor, atopy accounts for up to 90% of the allergies that cause allergic dermatitis. Only a small percent of these pets with atopy also have a food allergy at the same time.

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Symptoms

The most consistent symptom in pets with allergic skin disease is excessive itching. The medical term for this is pruritis. High strung dogs might itch more than placid dogs. Chewing, biting, or licking, or rubbing the skin can all be manifestations of pruritis.

Dogs can chew so incessantly that they wear down their incisor teeth to the gumline.

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In dogs some of the most common areas for pruritis to occur are the face, feet, and armpit areas. As the problem progresses the whole body might be involved. Some pets will scratch excessively but not show any problems with their skin.

If your pet has an allergy to fleas you might find tiny blood spots where it has been. These are the result of flea dirt that has fallen off your pet and become wet. Since flea dirt is made up mostly of blood, they appear as small blood spots on the floor or table tops.


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## MSK (Aug 13, 2008)

Diagnosis

Since the symptoms of allergic skin disease mimic those of other skin diseases, a thorough approach is needed to differentiate them. In every disease we encounter we follow the tenets of the "diagnostic process" to ensure that we make an accurate diagnosis, and that we do not overlook some of the diseases that are also encountered in conjunction with skin diseases.

1. Signalment

Typically, atopy occurs in mature dogs between 1- 3 years of age, although it can occur earlier (Shar pei's can get it as early as 3 months). The condition rarely starts in dogs over 6 years of age.

Most dogs get their first exposure to an allergen and develop sensitization in their first exposure to a pollen season. Symptoms usually occur during their second season of exposure to the pollen allergen when the immune system has its exaggerated response to the allergen and produces high levels of IgE. Dogs that are highly allergic can show signs of atopy during their first season of exposure to pollen allergens. It depends on how long the pollen season lasts and how rapidly their body produces the IgE antibodies.

Several canine breeds are prone to getting atopy. They include, but are not limited to:

Terriers Beagle
Retrievers Setters
Lhasa apso Miniature schnauzer
Shih Tzu Pug
Cocker spaniel Boxer
Dalmatian Shar Pei



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2. History

Atopy tends to be a progressive disease with worse symptoms each allergy season. Many dogs will be more affected during a specific season. As time goes on dogs can have allergies year round. It is not a contagious disease, so other dogs, cats, and people in the same household do not usually have symptoms (unless of course it is another dog that is highly prone to allergies).

The progeny of atopic dogs are more prone to developing atopy than other dogs. Careful breeding therefore can help minimize the occurrence of this problem.

Pets that have been treated with cortisone in the past, and did not improve, give us a clue that something else besides an allergic disease is involved.

Food allergies in dogs and cats can start at any time in a pet's life, even those on the same diet for a long period of time. Non-seasonal allergies bring food allergies to mind, along with vomiting or diarrhea, although these are not consistent findings. The skin lesions in food allergy are indistinguishable from atopy, but have a propensity to show only inflammation of the ears. Feeding dog and cat foods that contain ingredients that pets are routinely allergic to might also clue us in to a food allergy. This includes the premium foods and those that contain lamb.

Flea allergies are suspected whenever we are presented with a pet that has a skin condition and is not on routine flea control. This is true even for pets that never go outside. Other pets in the household that are itching might also indicate fleas in the environment. 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.

3. Physical Exam

The physical exam of a dog with a skin condition is the same as any other sick pet. We examine the whole body for clues as to the cause of the skin condition. The distribution of the skin lesions gives us a clue as to the cause, but is not consistent in all skin conditions.

Some of the more common exam findings are:

Pyoderma

A skin infection.

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Conjunctivitis

This is an inflammation of the eyes.

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Lichenification and hyperpigmentation

Chronic licking and scratching can cause thickening and dark pigmentation of the skin.

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Acute Moist Dermatitis

Commonly know as a hot spot. 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.

The serum that is exuded from the inflamed skin matts the hair and causes the problem to progress under the haircoat without anyone realizing how serious it is.

Hot spots can progress and cause serious skin conditions. This is painful and requires immediate care.

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Otitis externa

This is an infection of the outer ear canal. Sometimes this is the only symptom of allergy, especially food allergies. This ear is so severely infected that it is difficult to ascertain the normal anatomy. The ear canal is completely occluded, necessitating surgery to correct it.

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Pododermatitis

Infection of the feet can occur from chronic licking.

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Acral Lick Dermatitis

These are commonly known as lick granulomas. 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.

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Fleas or flea dirt

Flea dirt is literally 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. This is an example of lots of flea dirt.

Flea eggs are small white particles, similar in size to flea dirt, that fleas lay in a pet's haircoat. They eventually drop off and contaminate the environment. A pet can have fleas, yet show no evidence of fleas, flea dirt, or flea eggs.

Flea allergy dermatitis typically does not cause hair loss around the face, eyes, and ears like in atopy.

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4. Diagnostic Tests

Diagnostic tests are important even if we strongly suspect an allergy. In some situations other skin diseases can occur simultaneously with the allergy. It is impossible to make a diagnosis in any skin condition just by looking at it. This is because there are many diseases that affect the skin, yet the skin has only a limited number of ways to exhibit signs of disease.

Skin Scraping

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

Fungal Tests

Ringworm can mimic allergy symptoms. Lesions from Ringworm tend not to be as pruritic as allergies.

Malassezia, another fungus, is commonly associated as a secondary problem when the skin is infected. Even though it is a normal part of an animals 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. These symptoms can occur with other diseases also.

Malassezia is diagnosed by the above symptoms and looking for the organism under the microscope after swabbing the skin and placing the discharge on a microscope slide. Many pets respond to shampooing with specific antifungal shampoos twice weekly. These topicals will only work when the underlying allergy and its associated skin infection are under control. In some cases we use oral antifungal medications to control the problem.

Thyroid Test

Hypothyroidism can cause skin conditions, although dogs with only hypothyroidism are not terribly pruritic.

Fecal Exam

Hypersensitivity to internal parasites can cause symptoms similar to atopy. This is not a common situation.

Skin Biopsy

In some cases it is difficult to make a diagnosis. When we are presented with this situation we will biopsy several small pieces of infected skin and have them analyzed by a veterinarian that specializes in tissue analysis of the skin.

Here is a typical report from one of them. all of the big words mean that in this skin biopsy an allergy is most likely, but autoimmune disease cannot be ruled out for sure.

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Allergy Testing

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. If giving allergy shots is not contemplated then this test is of less value, although it will let us know what allergens we want to avoid. Trying to avoid these allergens though is almost impossible.

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

Intradermal (skin) Test

Most of us are familiar with the first one. 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.

This test is very subjective, and therefore prone to errors in interpretation, and therefore requires significant experience. Many different techniques are used.

Your pet must be off of oral cortisone medication for at least 1 month before testing. If injectable cortisone is given, the waiting time is longer. Your pet must not be on any tranquilizers at the time of testing and must be off of any 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 occurring. 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.

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RAST (in vitro test)

The second type of test that is performed is called the RAST test. RAST stands for radioallergosorbent test. Another in vitro test is called the ELISA (enzyme linked immunosorbant assay) test. RAST 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.

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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. There is a food manufactured by Hills called Z/D that has been a big help in diagnosing and treating food allergies.

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Routine Blood Panels

On occasion a specific type of white blood cell, called an eosinophil, is elevated in allergic conditions. Other conditions, notably worms, 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


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## MSK (Aug 13, 2008)

Treatment


In the early years of atopy the pruritis is more easily controlled. As the problem progresses treatment is not as rewarding. Chronic changes to the skin can occur, especially lichenification and hyperpigmentation.

Treatment is aimed at all the factors that contribute to pruritis. For example, a pet that is normally not atopic might become so if exposed to fleas or if it gets a pyoderma. This concept is called summation of effects, and might push the pet over what is called the pruritic threshold.

Avoidance

Obviously, if it is exposure to an allergen that causes the problem in the first place, then logic will dictate that we 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 under the pruritic threshold.

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 use synthetic material for your pets bedding. Pets allergic to house dust mites might do better 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. Rinse 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. Even think about replacing your carpets with wooden flooring. Keep your pet away from damp areas like basements (in California that's easy since we don't have many) and use humidifiers and air conditioners in humid weather. Rinse their 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 cylindric 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, we cannot emphasize the importance of proper flea control in any pet that has a skin condition. Even pets that are 100% indoors are possible flea victims.

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© , Revolution©, and Frontline©. We have detailed brochures on each to explain how they work, please ask one of our receptionists.

There is a new product that will be of significant help in outdoor dogs and cats. It is called Revolution©. In addition to treating fleas, it treats heartworm, ear mites, and internal parasites (depending on the species). This is a huge spectrum of control, and will probably become the future standard. We also have detailed brochures on this product.

Anti-inflammatories

Cortisone

One of the mainstays of therapy for treating atopy is cortisone, commonly know as steroids. These steroids fit in the class of drugs called corticosteroids, which are not the same thing as anabolic steroids used by bodybuilders. 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.

Cortisone is a very potent drug used in human and veterinary medicine literally thousands of times each day. Without this drug we would not be able to treat a large number of diseases. Cortisone has been abused by some people, leading to a bad name for this drug in some people's minds. When used judiciously, and under a doctor's supervision, it is one of the most important drugs we have.

Cats are more resistant to the side effects of cortisone than dogs. Some cats are difficult to pill, 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 sugar 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 routinely use cortisone for 1-2 weeks to help get the scratching problem under control. Since cats are more tolerant to cortisone, and can be difficult to pill, it is not unusual to use the injectable version of cortisone in them.

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 cases. They counteract the release of histamine (that's why they are called antihistamines) from the mast cell, which as you know is the source of the itching. They 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.

We will initiate an antihistamine trial to determine which one, if any, is most effective for your pet. We do a trial for up to 2 weeks to determine if one is effective or not. It is helpful not to have your pet on cortisone at the same time we are trying a new antihistamine, since we will not know if a decrease in pruritis is due the cortisone or the antihistamine. If we find one antihistamine that works well we stay with it on a long term basis. Eventually this might change, and if there is a significant flare up we will use cortisone 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 A
Atarax
Tavist
Chlorphenaramine
Amitryptiline

Medications used to treat allergic dermatitis are used on a long term basis. We will refill medications as needed, and require a complete physical exam every 6 months to verify we are still treating the correct problem and to check for potential side effects to medication. A blood sample will be recommended periodically to verify the health of internal organs that might be affected by long term medication.

Antibiotics

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

If a hot spot is present it will be gently clipped and cleansed. Pets with hot spots must be put on antibiotics and usually short term cortisone to prevent the problem from progressing. Hot spots are very painful, and oftentimes require sedation if the wound is to be clipped and cleansed properly.

Antibiotics that work best for pyoderma include:

Cephalexin
Baytril
Clavamox
Antifungals

Secondary fungal infections can occur, especially when the feet are licked constantly. The most common one is called Malassezia. It is treated with topical antifungals in most cases.

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 it to be used. Its main advantage is the fact it works without any side effects on a long term basis that can be encountered in drugs like cortisone.

It can be highly effective, but might cause vomiting and diarrhea, which might resolve on its own after a period of time. 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 we will decrease the dose slowly, with the ultimate goal of giving it twice per week. It becomes cost effective at this twice per week dosing, and it is probably warranted 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, and allergy shots can be custom designed for your pets specific allergy. 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.

Even if you do not give the allergy shots, knowing what your pet is allergic to can be beneficial in some cases, assuming you can remove the offending allergen (see previous section on avoidance). We tend to rely on allergy shots when avoidance methods and medication are unsatisfactory in minimizing pruritis.The company that performs the RAST test also supplies us with the allergens to give the allergy shots.

Giving allergy shots can be a significant way to minimize your pets scratching, although just like in people, no guarantee can be given to the outcome. Estimates vary, but in general, you can expect some improvement 60% of the time. In some cases we will still keep your pet on an antihistamine or cortisone, or Atopic©, but 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 it is a small amount with a tiny needle. We will teach you how to give them, and if need be, will give them for you. Initially, the injections are given every few days for several months. It takes at least several months to know if the injections are working, and up to a year for full effectiveness. Eventually, they are only given from once every few weeks to only a few times per year. Each pet's response is different.

Allergens are made specifically for each pet. This dog is allergic to many things, so three vials are needed to treat its problem.

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Food Allergy

Hypoallergenic means foods that your pet has never eaten, which technically, it cannot be allergic to. Even though food allergies are not a common cause of skin conditions in dogs, we recommend using these foods. It will take up to 2 months to know if the food is working. You cannot feed any other foods or treats during this trial period, so plan on rewarding your pet with something else besides food.

Hypo allergenic foods that contain fish, lamb, potato, or venison used to be the most effective. We now recommend Hills Z/D© as the most effective treatment for food allergy.

It is important that you do not have your pet on cortisone or antihistamines while trying to determine if your pet has a food allergy, since they will decrease the scratching and lead to an erroneous conclusion on the effect of the food. This causes a dilemma for those pets that have significant scratching, since they need immediate relief. In these cases we recommend using medication initially and starting your pet on a hypo-allergenic diet at the same time. If the itching is decreased after 1-2 months you can start weaning your pet off the medication to determine if the scratching is still diminished while on the hypo-allergenic diet also. In some cases we find the use of this food will allow us to use less medication to control the scratching.

Room Purifier

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

Food Supplements

Some allergic dogs and cats scratch less when supplemented with essential fatty acids. The main ones we use are Derm Caps and EFA-Z. As with other therapeutic options, essential fatty acids will not work when the skin has pyoderma. It will take at least several weeks of supplementation to see any improvement. In some cases the need for inflammatory medication will be reduced when a pet is put on essential fatty acids supplementation.

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Bathing

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. Bathing your pet too often will dry its skin out and increase its itchiness.

We have many different shampoos that will help you- please ask one of our receptionists to show you. We have had best results with oatmeal shampoos and rinses, along with antihistamine shampoos and rinses. Use a mild shampoo once weekly to keep the haircoat clean without drying it out. For hot spots we use Oxydex shampoo. If we suspect a secondary fungal infection caused by Malassezia we will use an antifungal shampoo called chlorhexidine.

This is an allergic reaction to shampoo in the arm pit area of a 8 month old female pit bull named Pumpernickel. This illustrates the principal that many things can cause an allergic reaction, even treatments for allergies.


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## MSK (Aug 13, 2008)

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Topical Medications

There is a strong tendency on the part of pet owners to use topical medications for allergic skin disease. They are used, and are helpful, but should not be relied upon as the primary source of treatment. Topical medications we use usually have an antibiotic, an antihistamine, or cortisone as ingredients. We tend to use topical agents most often when presented with pets with hot spots. In these cases we use antibacterial creme in addition to antibiotics that are given orally.

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Prognosis

Allergic Dermatitis is a chronic disease that is not cured, only controlled. It can be the cause of significant frustration, and will wax and wane in some cases. Understanding this disease will help you formulate a long term plan that suits your needs and minimize the chance of side effects when medications are used on a long term basis.


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## MSK (Aug 13, 2008)

Subject: Allergic Skin Diseases, by Marion Coffman Sat 31 May 2008 - 11:21 
Allergic Skin Diseases
by Marion Coffman


Most breeds of dogs have allergies to certain substances, the 3 most common being food, inhaled substances, or injections such as vaccines, insect bites or drugs.

The most devastating allergic reactions come from injected allergens, most often insect bites. By the time the owner realises that his dog has been bit and is suffering distress, it is often too late to save the animal. The reaction to a bite can be so immediate that there isn't enough response time available and the dog will go into shock and respiratory failure.

Inhalant allergies and food allergies represent the most common reactions, not related to parasites, in dogs. Most of these allergy problems are not life threatening but interfere with the full enjoyment of life because of the annoyance of skin, gastrointestinal, and respiratory problems. Besides being a source of discomfort to the dog, they are also frustrating to the owner looking for a solution to the problem.

Allergic inhalant dermatitis is one of the most common skin problems presented to the veterinarians. Affected dogs react to a variety of inhalants including house dust, feathers, grass, tree and weed pollen. Moulds often cause allergies and occur all year long. They produce a vast number of small spores that outnumber even the pollen in the air. This is especially hard on owners of hunting dogs as the allergy causes immediate reaction of wheezing, coughing, chewing at the feet and discharge in the eyes.

More often though, inhalant allergies will show up as they affect the skin. Dogs develop itchiness, hair loss and hives in the groin, flanks and armpits. Many dogs rub their faces on the furniture to relieve the itching and inflammation on the face and ears. Secondary skin infections develop in the traumatised areas, resulting in hot-spots - red and moist lesions with hair loss in the center. Antibiotics are needed to combat the infections and testing can be done to determine which allergies affect your dog.

Veterinary dermatologists usually rely on skin tests to confirm the diagnosis and to identify specific allergens to which the dog is allergic. Skin testing involves shaving the hair off the dog’s side, then injecting minute amounts of allergy extracts of various compounds known to cause allergy. The skin is examined at 15 minutes and again at 30 minutes. Swelling and inflammation around one or more of the test substances helps identify the culprit and, once the cause is known, hypo-sensitisation can be attempted. Although individual responses vary, most dogs can be sufficiently desensitised to give them relief.

Having your dog avoid inhalant allergens is rarely practical unless it is proven that the problem is a contact allergy. In that case environmental control can be aimed at by limiting the exposure to the allergens by removing substances such as wool, house plants and even plastic food dishes. Topical therapy using a variety of shampoos will often make the allergic dog more comfortable. Colloidal oatmeal can also be added to the bath water and has a soothing effect.

Immunotherapy (allergy shots) is a slow process sometimes taking up to a year before improvement. Antihistamines are useful and the advantage in using them is that they are relatively safe compared to corticosteroids.

Some dogs develop allergies to food, rawhide chews, medications or other ingested substances. These allergies most often show up as skin problems and not as digestive upsets. Although food allergies are relatively uncommon they are an important cause of severe itching in dogs. The clinical signs of food allergy are very much like those of many other allergic conditions except that clues that the diet is at fault may be that food allergy is not seasonal and that, unlike flea or inhalant allergy, it is not easily relieved by treatment with corticosteroids. Since food allergy is uncommon, other sources should be excluded before you blame it on the diet.

Many affected animals have been fed the offending food 2 or more years before developing any clinical signs. Clinical signs may develop at any age, even appearing before the dog is 9 months of age or after the dog is old (more than 8 years).

For most food hypersensitivities the symptoms are all year round, being typically abrupt in onset and only affecting one dog in the household though all are on the same diet. The symptoms may progress to loss of appetite, weight loss, itchy reddened skin and hair loss especially on the head, feet, armpits, groin and ears. Vomiting, diarrhea, sneezing, asthma-like conditions and behavioral changes may occur.

The only way to be certain that the diet is the problem is by dietary restrictions. Just changing from one commercial pet food to another is not the answer because many of these diets contain the same ingredients. The most common causes of food allergies are beef, pork, chicken, milk, corn, soy, whey, eggs, fish and preservatives.

The easiest way to check for food allergies is to put the dog on an elimination diet. This diet usually consists of nothing except pure lamb (editors note: remember that all sheep products in New Zealand should be cooked or frozen to standards required for destruction of hydatids and sheep measles) and rice. Your veterinarian will work out with you to reintroduce particular foods until the offending ingredients are discovered.

Hypoallergenic diets must contain ingredients not previously encountered by the patient and all other sources of potential or offending substances should be excluded including rawhide chews, table scraps and vitamin and mineral supplements.

Response to the hypoallergenic diet rarely occurs within the first week. If the dogs skin condition improves by the twenty-first day diet is probably at fault and the animal will be put back on the original diet. If the animal’s itchiness increases, there is no doubt what the problem is. In this case you will need to find a diet that is both nutritionally sound and free of the offending substances.

Many food allergic dogs can safely eat commercially prepared hypoallergenic diets. Introduction of individual dietary antigens can be based on a list of ingredients in the dogs original commercial meal. For the dog eating foods containing dried whey, powdered milk can be mixed into the daily ration. If there is no resumption of the itching within 7 days, ground beef can be substituted for the lamb. If neither of those ingredients causes itching, wheat flour and then soy or corn meal can be added in a similar manner. If there still is no resumption of itching, the dog can be placed on a commercial diet free of additives, preservatives and artificial flavours and colours.

Avoidance of the offending foods is the only specific and practical treatment of food allergies.


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## iluvbigran (Sep 13, 2012)

My Pitty has Demodex & Flea Allergy!! It makes it Really hard to know which is the reason for hair loss at any given time! Especially since we live in Texas & fleas just come with the territory!


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