Allergies in Dogs

From ASPCA
http://www.aspca.org/pet-care/dog-care/dog-care-allergies.aspx

What Are Allergies?

Just like people, dogs can show allergic symptoms when their immune systems begin to recognize certain everyday substances—or allergens— as dangerous. Even though these allergens are common in most environments and harmless to most animals, a dog with allergies will have an extreme reaction to them. Allergens can be problematic when inhaled, ingested or contact a dog’s skin. As his body tries to rid itself of these substances, a variety of skin, digestive and respiratory symptoms may appear.

What Are the General Symptoms of Allergies in Dogs?

• Itchy, red, moist or scabbed skin
• Increased scratching
• Itchy, runny eyes
• Itchy back or base of tail (most commonly flea allergy)
• Itchy ears and ear infections
• Sneezing
• Vomiting
• Diarrhea
• Snoring caused by an inflamed throat
• Paw chewing/swollen paws
• Constant licking

Allergic dogs may also suffer from secondary bacterial or yeast skin infections, which may cause hair loss, scabs or crusts on the skin.

Which Dogs Are At Risk for Getting Allergies?

Any dog can develop allergies at any time during his life, but allergic reactions seem to be especially common in terriers, setters, retrievers, and flat-faced breeds such as pugs, bulldogs and Boston terriers.

What Substances Can Dogs Be Allergic To?

A few common allergens include:

• Tree, grass and weed pollens
• Mold spores
• Dust and house dust mites
• Dander
• Feathers
• Cigarette smoke
• Food ingredients (e.g. beef, chicken, pork, corn, wheat or soy)
• Prescription drugs
• Fleas and flea-control products (The bite of a single flea can trigger intense itchiness for two to three weeks!)
• Perfumes
• Cleaning products
• Fabrics
• Insecticidal shampoo
• Rubber and plastic materials

Can Dogs Be Allergic to Food?

Yes, but it often takes some detective work to find out what substance is causing the allergic reaction. Dogs with a food allergy will commonly have itchy skin, breathing difficulties or gastrointestinal problems like diarrhea and vomiting, and an elimination diet will most probably be used to determine what food he is allergic to. If your dog is specifically allergic to chicken, for example, you should avoid feeding him any products containing chicken protein or fat.
Please note that food allergies may show up in dogs at any age.

What Should I Do If I Think My Dog Has Allergies?

Visit your veterinarian. After taking a complete history and conducting a physical examination, he or she may be able to determine the source of your dog’s allergic reaction. If not, your vet will most probably recommend skin or blood tests, or a special elimination diet, to find out what's causing the allergic reaction.

How Are Dog Allergies Diagnosed?

If your dog’s itchy, red or irritated skin persists beyond initial treatment by a veterinarian, allergy testing, most often performed by a veterinary dermatologist, is likely warranted. The diagnostic test of choice is an intradermal skin test similar to the one performed on humans.
The only way to diagnose a food allergy is to feed your dog a prescription or hydrolyzed protein diet exclusively for 12 weeks. The importance of not feeding your dog anything but the diet cannot be emphasized enough—that means no treats, table food or flavored medication. This diet will be free of potential allergy-causing ingredients and will ideally have ingredients your dog has never been exposed to. He’ll remain on the diet until his symptoms go away, at which time you’ll begin to reintroduce old foods to see which ones might be causing the allergic reaction.
Please note, many dogs diagnosed with a food allergy will require home-cooked meals—but this must be done in conjunction with your veterinarian, as it requires careful food balancing.

How Can Dog Allergies Be Treated?

The best way to treat allergies is to remove the offending allergens from the environment.

• Prevention is the best treatment for allergies caused by fleas. Start a flea control program for all of your pets before the season starts. Remember, outdoor pets can carry fleas inside to indoor pets. See your veterinarian for advice about the best flea control products for your dog and the environment.
• If dust is the problem, clean your pet's bedding once a week and vacuum at least twice weekly—this includes rugs, curtains and any other materials that gather dust.
• Weekly bathing may help relieve itching and remove environmental allergens and pollens from your dog’s skin. Discuss with your vet what prescription shampoos are best, as frequent bathing with the wrong product can dry out skin.
• If you suspect your dog has a food allergy, she’ll need to be put on an exclusive prescription or hydrolyzed protein diet. Once the allergy is determined, your vet will recommend specific foods or a home-cooked diet.

Are There Allergy Medications for Dogs?

Since certain substances cannot be removed from the environment, your vet may recommend medications to control the allergic reaction:

• In the case of airborne allergens, your dog may benefit from allergy injections. These will help your pet develop resistance to the offending agent, instead of just masking the itch.
• Antihistamines such as Benadryl can be used, but may only benefit a small percentage of dogs with allergies. Ask your vet first.
• Fatty acid supplements might help relieve your dog’s itchy skin. There are also shampoos that may help prevent skin infection, which occurs commonly in dogs with allergies. Sprays containing oatmeal, aloe and other natural products are also available.
• An immune modulating drug may also be helpful.
• There are several flea-prevention products that can be applied monthly to your dog’s skin.
• If the problem is severe, you may have to resort to cortisone to control the allergy. However these drugs are strong and should be used with caution and only under the guidance of your veterinarian.

Are Allergies and Bronchitis Related?

Chronic exposure to inhaled irritants (including cigarette smoke) may be a cause of bronchitis in the dog. Bronchitis is characterized by a persistent cough due to inflammation of the airway and excessive mucus production. Treatment may include medication to open breathing passages, antibiotics and anti-inflammatory agents. Please remember, your pets should not be exposed to cigarette smoke.