Allergies in Dogs

If your dog is persistently chewing its feet or scratching at its face, allergy may be a possible cause. Unfortunately, there are no specific signs for allergy so you will need to rely on your pet's veterinarian to make that determination. Allergy diagnosis requires eliminating other causes for your pet's clinical signs. This involves taking a detailed history of your pet's problems, a complete physical examination, and some preliminary laboratory tests. If your pet's history and physical examination suggest that an allergy is likely, your veterinarian may recommend allergy assessment to identify the offending allergens.

The Signs:

The most common sign of dog allergies is itching of the skin, either localized (one area) or generalized (all over the dog). Pets are scratching, face rubbing, biting and chewing at the skin. Usual locations for signs of allergy are the flank, feet, and face, particularly around the eyes, mouth and ears, as well as areas around the base of the tail. In dogs, allergies are often the underlying cause of persistent skin disease; however, it is important to note that not all scratching is due to allergy. Conditions such as thyroid disease, fleas and certain infections, such as ringworm, can cause similar signs. Your dog may have coughing, sneezing, and/or wheezing. Sometimes there may be an associated nasal or ocular (eye) discharge. Some dogs have vomiting or diarrhea.

The Causes:

In the allergic state, the immune system "overreacts" to foreign substances (allergens or antigens) to which it is exposed. Allergies occur whenever the offending allergens are present. The more common allergens, such as house dust mites or mold spores, will produce signs of allergy year round, while allergies from plants that pollinate during warm months are apt to cause allergies only when they pollinate. Food allergy may occur by itself or it may be a component of an overall allergy problem. Because of the complexity of allergy diagnosis, the combination of patient history, physical examination, and allergy signs in the pet are all important in making an accurate diagnosis.

  • Flea Allergy

Fleas are one of the most common causes of pruritic or itchy skin disease in pets. There are two ways fleas can cause a pet to itch. The presence of the fleas crawling around in the fur causes the pet to scratch and bite the skin. Once the pet starts itching, the self-trauma to the skin causes the pet to itch more. If the physical presence of fleas is not enough to make the pet itch, some pets are also allergic to the saliva of the flea. Many pets are extremely sensitive to the saliva from the fleabite although the pet may have little evidence of flea infestation. These animals may develop a condition known as flea allergy dermatitis (FAD). FAD is a very pruritic disease and predisposes the pet to secondary bacterial or yeast infections of the skin. Because the pet is so pruritic they groom themselves excessively, eliminating any evidence of fleas. A couple of fleabites every two weeks are sufficient to make a sensitive pet very pruritic without any physical evidence of fleas. FAD should be considered a progressive disease, with each “flea season” resulting in an increasingly severe reaction in the allergic pet. A well-planned flea control strategy is essential to maintaining the health and comfort of both the pet and the owner. Pets that have FAD may never reach a level of zero itchiness, so flea control should be directed at trying to keep fleas off of the pet.

  • Inhalant Allergy

The most common type of dog allergies is the inhalant type, or atopy. Dogs may be allergic to all of the same inhaled allergens that affect humans. These include tree pollens (cedar, ash, oak, etc.), grass pollens (especially Bermuda), weed pollens (ragweed, etc.), molds, mildew, and the house dust mite. Many of these allergies occur seasonally, such as ragweed, cedar, and grass pollens. Others are with us all the time, such as molds, mildew, and house dust mites. The dog's reaction usually produces severe, generalized itching. In fact, the most common cause of itching in the dog is atopy (inhalant allergy). Most dogs that have inhalant allergy react to several allergens. If the number is small and they are the seasonal type, itching may last for just a few weeks at a time during one or two periods of the year. If the number of allergens is large or they are present year-round, the dog may itch constantly.

  • Bacterial Allergy

There are many types of Staphylococcus (Staph) bacteria; this is the least common of dog allergies. If the skin is normal and the dog's immune system is normal, Staph causes no problems. However, some dogs develop an allergy to this bacterium. When this happens, the dog develops areas of hair loss that look much like ringworm. They are often round and 1/2 to 2 inches (1-5 cm) in diameter. These same lesions develop in true Staph infection; they are easily treated with certain antibiotics, but the Staph-allergic dog has recurrent "Staph infections." The lesions will usually clear with appropriate antibiotics but return as soon as antibiotics are discontinued. After a while, some dogs become resistant to antibiotic treatment. Treatment of Staph allergy involves antibiotics to control the immediate problem and desensitization with Staph antigen for long-term relief.

  • Food Allergy

Dogs are not likely to be born with food allergies. This is the second most prevalent of dog allergies. It often shows up as inflammation of the ears. Dogs develop allergies to food products before 1 year of age or after 5 years of age. The allergy most frequently develops in response to the protein component of the food; for example, beef, pork, chicken, or turkey, or dairy products. Food allergy may produce itching, digestive disorders, and respiratory distress. Testing is done with a special hypoallergenic diet. Because it takes at least eight weeks for all other food products to get out of the system, the dog must eat the special diet exclusively for 8-12 weeks (or more). If the diet is not fed exclusively, it will not be a meaningful test. We cannot overemphasize this. If any type of table food, treats or vitamins are given, these must be discontinued during the testing period. There may be problems with certain types of chewable heartworm preventative, as well.



FLEA PREVENTION - The most important treatment for flea allergy is to get the dog away from all fleas. Therefore, strict flea control is the backbone of successful treatment. There are several medications for getting rid of and keeping fleas off your dog; check with your vet. You should try to keep the dog’s environment as flea-free as possible.


SOOTHE IT TOPICALLY - Calendula ointment is an herbal medication that has been successfully used to relieve the itch. Apply a thin coat twice daily to affected areas. If your pet has chewed or scratched sore spots on skin, hydrocortisone cream can be applied. Do not let the pet lick the area.


BATH - An oatmeal shampoo with cool water will ease the itchiest skin. Leave the shampoo on for 10 minutes then rinse well. With the most severe allergies, bathe your pet twice weekly.


CLEAN ENVIRONMENT - The goal is to eliminate your pet’s exposure to fleas, dust mites, molds, and fungi as much as possible. Environmental controls include frequent vacuuming and mopping all floors, washing kennel floors, and washing the pet’s bedding. If flea infestation is severe you may need commercial extermination and outdoor spraying every 2-3 weeks. All pets should be removed from premises during environmental treatments.

IMMUNOTHERAPY - In pets with more severe allergies, or in pets where allergies occur year round, specific immunotherapy (allergy shots) may be needed. Your pet's veterinarian will discuss various alternative treatments with you based on your needs and the needs of your pet.

The success of treatment depends on several factors including the overall health of your pet and a commitment to therapy. In general, the steps to successful allergy treatment involve the following: (1) trying to avoid or reduce the allergens in the environment, (2) giving recommended medications to control clinical signs and (3) identifying the specific allergens causing clinical signs in your pet early in disease, followed by allergy immunotherapy. The combination of these therapies will result in successful allergy treatment in the majority of pets.


Lakeside Veterinary clinic assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.