My Dog Won’t Stop Scratching: Understanding Pet Allergies
Are Pet Allergies Causing Your Dog To Constantly Scratch And Chew Themselves?
Fall in the Ozarks brings less humidity, cooler weather, colored leaves, and unfortunately ragweed. Fall means hay fever symptoms in people and allergic dermatitis in our pets. Unlike humans, most pets show signs of allergies through their skin. So, what are pet allergies? An allergy is a state of over-reactivity or hypersensitivity to an allergen. Most allergens are proteins. The allergen protein may be of insect, plant or animal origin. Some allergens are inhaled, some allergens are ingested and some allergens cause contact irritation. No matter the route of exposure, the end result is an itchy dog if your pet suffers from allergies. The itching is caused by an overactive immune system reaction. This can sometimes happen with the first allergen exposure but often it requires multiple exposures to the offending allergen. An antibody in the blood called Immunoglobulin E (IgE) binds to the allergen protein. This allergen-IgE complex then attaches to a Mast Cell. When attached to an allergen complex, Mast Cells break up and release potent inflammatory compounds such as histamine. This starts the inflammatory cascade and the allergic reaction. This allergic reaction can happen anywhere on the skin of your dog. The medical term for this is allergic dermatitis or atopy.
There are numerous substances that can act as allergens. Flea saliva, tick saliva, tree pollens (cedar, oak, ash), flower pollens, grasses and weed pollens (ragweed), as well as molds, mildew, and house dust mites are the most common allergy offenders. Some plant and animal proteins found in foods can cause allergies as well as some food additives. The most common cause of allergies in our pets is fleas and the least common cause of allergies is food. Up to 80% of our pets with allergic dermatitis are very allergic to fleas so flea control is absolutely essential in the allergic pet.
SIGNS OF ALLERGIC DERMATITIS:
The most common sign of allergies is itching of the skin –either in one area or generalized over the body. Itchy signs can include chewing and licking of the feet, rubbing or pawing at the face or eyes, rubbing the head or ears along the carpet or sofa, rubbing the belly or rear on the floor, and redness of the skin in the affected areas. Many pets will lick their armpits, thighs, belly or abdomen. Scratching at the ears or ear flicking and head shaking is also indicative of allergies. The constant scratching and licking can result in a secondary bacterial skin infection. Other signs of allergies may also include reoccurring ear infections, full anal glands and anal gland infections.
BREEDS PREDISPOSITION :
Many dog breeds are predisposed to allergies. Terrier breeds as a group are the most commonly affected dogs that we see in our practice. Schnauzers, Westies, Scottish, Cairn, Welsh, Fox, Boston and Jack Russell Terriers are just a few that can be afflicted with allergies. Golden Retrievers, Labrador Retrievers, Boxers, Bulldogs, Shih Tzus, Cocker Spaniels, and Shepherds are also commonly affected breeds. Most pets will start showing allergy signs between one and three years of age. Initially, many allergies will occur seasonally when the allergen is at its peak. But each year, the allergy season starts a little earlier and lasts a little longer and the allergies worsen. Eventually, with time, allergic dermatitis can become year-round. Allergens such as house dust mites, molds and mildew are present any season and pets sensitive to these will suffer year-round.
The best way to treat allergies is to individualize the treatment to your pet and to treat that patient with the lowest dose or frequency of medication possible because allergies are a life long problem. Eventually, your pet may need medication daily to control its allergies so starting with lower dose therapy initially will be of benefit. Keep in mind that some animals will respond better to different aspects of the therapy than others and some therapies may not work at all. Also remember that allergies are controlled and not cured. Seven possible allergy treatments include frequent bathing, antihistamine therapy, fatty acid supplementation, anti-inflammatory therapy, cyclosporine therapy, desensitization therapy, and/or food allergy trial. And as mentioned earlier, flea and tick control is essential in the allergic patient.
Keep in mind that each allergy patient is different and each treatment will be individualized to that pet. Some therapies will work better than others for different pets. Above all, remember that allergies are controlled at best. Allergies are not cured. Close communication with your veterinarian is essential in keeping your allergy pet as comfortable as possible.
Frequent bathing helps physically remove irritants that are on the surface of your pet’s skin. Bathing also helps control and removes infection causing bacteria from the skin. Some pets need be bathed weekly. It is very important to use a high-quality, hypoallergenic or medicated shampoo that will not dry out or irritate your pet’s skin when used regularly. Be sure to thoroughly rinse your pet after its bath. Your veterinarian will recommend the best shampoo and the best bathing schedule for your pet. Consider having your long-haired pet’s coat shaved during allergy season to assist you in bathing.
Antihistamines work the same in our pets as they do in us. By decreasing the release of inflammatory mediators, antihistamines help alleviate the symptoms of allergies. As is the case with people, different antihistamines will affect our pets in different ways. Some pets will become sleepy, others may become excitable, and some may show a decrease in appetite. Despite these few side effects, antihistamines are relatively safe to use on a daily basis and are most effective when given prior to and regularly through the allergy season. The biggest benefit to using these medications is that it allows us to avoid using steroids or allows us to use a lower dose of steroids.
Fatty acids are compounds in the body that are used as building blocks to form compounds such as histamine and prostaglandins. Histamines are compounds that can cause inflammation and allergies. Supplementing the diet with a non-body source of fatty acids may actually help decrease the amount of inflammatory mediators produced by the body because the oral fatty acid gets metabolized into different, less potent inflammatory mediators. Fatty acid supplements work in about 30 % of our patients. It is believed that some antihistamines and fatty acids work synergistically to achieve an even greater effect. Fatty acids also help moisturize and improve the condition of the hair coat which is important in our allergy patients.
Steroids are used when the above therapies are not effective or the allergies are so severe that the patient needs relief. Steroids are often used to help a patient survive through allergy season until allergy testing and desensitization therapy can be initiated. Steroids basically turn off the over-reactive immune system. Steroids do have side effects some of which can be serious. The most common side effects are increased thirst and urination, increased appetite and weight gain. Steroids also predispose pets to infections, especially bladder infections. Steroids can also interfere with your pet’s own hormonal regulation. There are short acting and long acting steroids. The severity of side effects is directly related to the potency of the steroid used. There are two basic forms of steroids. There is an injectable form and a pill form. The injectable form can last in your pet’s system for 2 to 3 months. The tablet form usually lasts for about a day. It is safer for your pet to be on the oral tablets at a graduated, tapered dose. The injectable form is used when your pet’s allergies are so severe that immediate relief is needed. Steroid treatment is a serious therapy that requires close attention by your veterinarian.
ALLERGY TESTING & DESENSITIZATION THERAPY:
This is the gold standard for a patient with allergic dermatitis. Your pet may either be skin tested or have blood drawn for an allergy test. The skin test involves injecting diluted allergens into your pet’s skin and looking for a flare skin reaction. The blood test is done in a specialized laboratory. The test looks for blood levels of IgE in response to antigens. Most allergy testing is done in the winter when your pet is no longer receiving medications. Once it is determined what your pet is allergic to, an allergen-specific immune serum can be compounded. This serum will have low levels of antigen that your pet will be exposed to by injections over a period of time – in effect desensitizing your pet to the allergens. The exact mechanism of action of immunotherapy is still unknown in the dog but it is postulated that immunotherapy decreases the levels of IgE antibodies and increases the levels of IgG antibodies along with altering T-helper cell response. Overall, desensitization improves allergy symptoms in about 50% of patients and the results can be very gratifying.
Cyclosporine is a chemotherapy drug. It has been altered and formulated into a low dose oral tablet called Atopica. Atopica is a potent immunosuppressor of T- helper cells and inhibits interleukin -2 which is an inflammatory mediator. These two actions help turn off the over reactive immune system response and provide relief for the allergy pet. Atopica does not suppress cell- mediated immune responses and therefore overall doesn’t adversely affect the pet’s ability to fight infections. It is only approved for use it dogs.
Is the newest generation anti-inflammatory medication used to control itching associated with allergic dermatitis? We have now treated over 80 patients at Deerfield in the past year with this new medication and have seen very positive results. Apoquel targets the pet’s immune system. It specifically addresses that part of the immune system that is involved in the itch and inflammatory response. Unlike
DON’T FORGET ABOUT FLEAS:
No amount of allergy treatment in the world will relieve your pet’s itching if your pet has fleas. As stated earlier, 80% of our pets with allergies are also allergic to fleas. It may take only one or two flea bites to cause an allergic reaction in your pet. One flea is one flea too many for a pet with allergies. Flea control is essential for an allergy patient.
We know it can be stressful to see your pet suffer. Feel free to contact us for further help and advise regarding your pet.