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One of the most common conditions affecting our dogs (and even our cats) is allergies. In the allergic state, the dog's immune system overreacts to foreign substances (allergens or antigens) to which he is exposed. These overreactions are manifested in any of three ways:

1. Itching of the skin - either localized (one area) or generalized (all over the dog). This is the most common presentation. The areas most commonly affected are the paws, the armpits, the groin, the belly and the ears.

2. Respiratory system signs such as coughing, sneezing, and/or wheezing. Sometimes there may be associated nasal or eye discharge.

3. Digestive system signs such as vomiting or diarrhea.

There are several different types of allergies in the dog: contact, flea, food, and inhalant are the most common. These will be explained in detail in the next several paragraphs.

There are several different types of allergies in the dog: contact, flea, food and inhalant are the most common. Each of these has some common expressions in dogs, and each has some unique features.




Contact allergy is the least common type of allergic skin condition in dogs. Contact allergy results in a local hypersensitivity reaction in the skin. Examples of contact allergies include reactions to flea collars, types of bedding such as wool or cedar, reaction to detergent used to launder blankets and beds, or even shampoos. If the dog is allergic to such substances there will be skin irritation at the points of contact. Removal of the contact irritant will solve the problem, however identifying the allergen can require some detective work.




Flea allergy is very common in dogs. A normal dogs experiences only minor irritation in response to flea bites, often without any itching. On the other hand, a flea-allergic dog has a severe, itch producing reaction when the flea's saliva is deposited in the skin. Just one bite causes such an intense itch that the dog may severely scratch or chew himself, leading to the removal of large amounts of hair. There will often be open sores or scabs on the skin allowing secondary bacterial infection to begin. The area most commonly involved is over the rump, just in front of the tail, but it can also be seen extending down the thighs or in other areas as well.

The most important treatment for flea allergy is the remove all fleas from the dog and the dog's environment. Strict flea control is the backbone of successful treatment. Flea control has come a long way since the days of flea collars, baths and smelly, toxic dips. We now have wonderful, safe, effective and long lasting products that kill, sterilize, and control fleas and ticks. You and your veterinarian should decide which products are best for you and your pet based on their lifestyle and your previous or present environmental conditions.

You can limit your dog's exposure to fleas by taking a few simple steps to eliminate as many immature fleas (eggs, larvae, and pupae) in the environment as possible.

  • VACUUM frequently wherever your dog has been, especially your car, carpeted areas, and any furniture your pets climb on. (Admit it, the dog does jump up on that sofa when you're not looking!)
  • WASH your dog's bedding, blankets and other washable items regularly in the hottest water possible. Check the laundering instructions for appropriate water temperatures for your dog's washables.
  • TAKE CARE OF YOUR YARD by mowing your lawn and raking up leaves, brush and clippings.

For more information on fleas and/or ticks please visit the Merrick Veterinary Group
July 2008 Monthly Update Archive.




Food allergy is one of the itchiest conditions known to cats and dogs. Animals eat a variety of processed food proteins, fillers, and colorings which are further processed inside their bodies. Proteins may be combined or changed into substances recognized by the immune system as foreign invaders to be attacked. The resulting inflammation may target the GI tract or other organ systems but, in dogs and cats, it is the skin that most often suffers from this immunologic activity.

Many people erroneously assume itching due to food allergy requires a recent diet change of some sort. In fact, the opposite is true. Food allergy requires time to develop; most animals have been eating the offending food for years with no trouble. The allergy most frequently develops from the protein source in the food; for example beef, pork, chicken, or turkey.

Food allergy may produce any of the signs previously discussed, including itching, digestive disorders, and respiratory signs. In cats, food allergy usually produces scabs and other signs of itching around the face or neck.

Veterinarians recommend testing for food allergy when the clinical signs have been present for several months, the pet has been treated for sarcoptic mange or other mites/infections without any positive change, the pet's itchiness is not and has never been a seasonal problem, the pet has responded poorly or only partially to cortisone-type medications, or when a very young dog itches with no other apparent cause of allergy.

Testing is done with a special hypoallergenic diet trial. Obviously, the test diet must be of a food source that the patient could not possibly be allergic to. The traditional method is the use of a novel protein and carbohydrate source; that is, something the pet has never eaten before. Because it takes at least eight weeks for all other products to get out of the system, the dog or cat must eat the special diet exclusively for 8-12 weeks (or more). If a positive response occurs, the original diet is then fed for up to two weeks to see if itching resumes. If we see recovery with the test diet and itch with the original diet, then food allergy is diagnosed and the pet is returned to either the test diet or another appropriate commercial food indefinately.

Where can I get a novel protein diet?

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, rabbit and pea, and even kangaroo. Our hospital generally recommends venison or fish and potato based foods for dogs and rabbit or venison and pea based foods for cats. We have chosen these products because they are available both as canned as well as dry formulas. However, we do offer several other varieties of hypoallergenic foods for pets that have a pickier appetite.

Please remember, if the diet is not fed exclusively during the trial, it will not be a meaningful test. This CANNOT be over emphasized. If ANY types of table food, treats or vitamins are given, these must be discontinued during the testing period. 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. There may be problems with certain types of heartworm preventative as well. Chewable preventative should be replaced with tablets.

For treats appropriate to dogs on a food trial see:

http://www.snookdog.com/ for sweet potato treats

http://www.sitstay.com/ for rabbit ear treats, venison sausage, carrot dental bones, turkey jerky strips, rabbit ear treats, icelandic fish chews, and other novel protein-based treats

What to Do if the Diet is Unsuccessful?

Generally, an unsuccessful food trial is strongly suggestive that an inhalant allergy is really the primary problem but there are some other considerations that should at least be mentioned: 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. Are you certain regarding the factor that pointed us toward the food allergy? If your pet has not been biopsied, now may be a good time. If an inhalant allergy has risen to the top of the list, symptomatic relief either via medication, special baths, or allergy shots will likely be necessary. Chronic itchiness can be extremely uncomfortable and prompt relief is the goal.




Canine atopic dermatitis (allergic dermatitis, canine atopy) is an inherited predisposition to develop allergic symptoms following repeated exposure to some otherwise harmless substance, an allergen. Common inhaled allergens include pollen, grass, trees, dander, mold, or any other airborne particles. Most dogs begin to show their allergic signs between 1 and 3 years of age. Due to the hereditary nature of the disease, several breeds, including golden retrievers, most terriers, Irish setters, Lhasa apsos, Dalmatians, bulldogs and Old English sheep dogs are more commonly atopic, but many dogs, including mixed breed dogs can have atopic dermatitis. The incidence is increasing both in man and animals.

Atopic animals will usually rub, lick, chew, bite or scratch at their feet, muzzle, ears, armpits or groin, causing hair loss, and reddening and thickening of the skin. In some cases several skin problems can "add" together to cause an animal to itch where just the allergy alone would not be enough to cause itching. These problems include air borne-allergens (pollens, etc.), allergens in food, and allergens from parasites (fleas, etc.) and also bacterial or yeast infections of the skin. Eliminating some but not all of the problems may allow a patient's itchiness to go away. Therefore it is important to treat any other problems that could be making your pet itch while dealing with allergy.

With cats, the most typical signs are multiple little scabs around the neck and head and along the center line of the back. We call this condition of multiple scabs miliary dermatitis. We now know that this is the same disease as atopy.

Diagnosis

Specific diagnosis of atopic dermatitis is based upon the results of intradermal skin testing and/or in vitro (blood) testing. Many medications can interfere with our ability to properly skin test your pet. Length of time that a medication's effect remain in an animal's body is highly variable; however, basic guidelines for withdrawal of medications are: At least 4 weeks off oral prednisone; 10 weeks after triamcinolone acetonide injection; 14 weeks after methylprednisolone acetate injection; 10 to 14 days off antihistamines; 10 to 14 days off topical steroids (ear drops, ear drops or medication for skin); 2 days off tranquilizers.

Treatment Options for Atopy or Allergic Skin Disease

We don’t have a cure for Atopic Dermatitis, but here’s what we can do to manage these cases and make your pet a lot more comfortable. Please note that it's not a realistic goal to stop 100% of the itch, but rather to control the problem enough to make the pet reasonably comfortable.

1) Antihistamines: This medication works in 20% of atopic patients. Your pet can take antihistamines for life. The only side effect usually seen is drowsiness. Several types may be tried to find the one best for your pet. Topical antihistamines for the eyes can be helpful in patients with eye allergy (itchy conjunctivitis).

2) Avoidance of the allergens: This can be helpful for house dust mite allergies. Pollen exposure can be reduced by using air-conditioning and air filters, avoiding the outside early morning and late afternoon, wiping down with moist cloths after going outside and frequent bathing.

3) Oral Steroids (prednisone, cortisone, triamcinolone, etc.): These drugs have many potential side effects and are reserved for adult animals, those with short seasonal problems or where other therapy is not possible or is ineffective. Typically, treatment is started at one dose and then tapered off to every other day usage.

4) Topical Steroids: Topical usage is safer than oral usage. It can be very helpful if itching is localized (e.g., eyes, ears). It can be used for more widespread disease in the form of leave-on rinses or lotions (ResiCORT®) or a triamcinolone spray (Genesis®).

5) Cyclosporine (Neoral®): This immunosuppressive agent can be used at low doses to treat allergy successfully in about 60% of patients. It can also be used to lower needed dosages of steroids. The major short-term side effect is gastrointestinal upset. The long-term safety is not completely known. The dosage can often be lowered after a few weeks of successful treatment.

6) Tacrolimus (Protopic® ointment): This drug is related to cyclosporine. It can be very useful for treating localized itchy areas in atopic dermatitis. It is applied once or twice a day at first, and then frequency is reduced.

7) Fatty acid supplements: Certain types of oils can reduce allergic symptoms in some patients. We can give fish oil capsules in conjunction with a low-fat diet or prescribe special prescription diets with the fish oil content raised. This therapy can help improve response to antihistamine therapy.

8) Bathing: Atopic skin is sensitive and subject to drying. Only specially designed hypoallergenic shampoos should be used on your allergic dog. Rinsing should be thorough. Generally it is best to follow with a hypoallergenic cream rinse or spray to remoisturize the skin after every bath. Virbac's Allermyl® comes as a shampoo or a spray and contains 1-rhamnose, which may reduce itch and inflammation, however there are several other good products available.

9) Antibiotics may be needed to treat secondary bacterial infections that arise from chronic licking and scratching of the skin and ears. These are usually prescribed for several weeks at a time to ensure that a recurrance of infection does not occur.

Most dogs that have atopic dermatitis are treated with a combination of therapies such as antihistamines, fatty acids and shampoos to obtain maximum relief of their symptoms.

If all of the above treatment options fail, or the use of steroids if unacceptable, there is another option:

Allergen Specific Immunotherapy/Hyposensitization

The final form of allergy treatment is hyposensitization with specific antigen injections (or allergy shots). Once the specific sources of allergy are identified through blood or skin testing, very small amounts of antigen are injected weekly. The purpose of this therapy is to reprogram the body's immune system. The goal as time passes is to have an immune system that becomes less reactive to the problem-causing allergens. If hyposensitization helps the dog it is continued for several years. For most dogs a realistic goal is for the itching to be significantly reduced in severity; in some dogs ithching may completely resolve.

  • This approach is NOT successful with food allergy.
  • Results may not be seen for 3 to 6 months.
  • When results are not seen in 9 to 12 months, a re-evaluation is necessary.

Although hyposensitization is the ideal way to treat inhalant allergies it does have some drawbacks and may not be the best choice in certain circumstances. Your veterinarian will discuss these with you and together you can make an informed decision about whether hyposensitization is right for your pet.

Please remember that approximately 50% of dogs will have an excellent response. About 25% of dogs will get a partial or good response. About 25% of dogs with get little to no response. The same statistics are true for people undergoing desensitization treatment.






If you think your dog or cat's itching and scratching may be due to allergies of any type please call the Merrick Veterinary Group at 516-379-6200 to schedule an appointment today.


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