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The most common fall season health problem in dogs is inhalant allergies to pollens, particularly ragweed. The predominant sign is generalized itching, rubbing, and licking without any visible reason.
Cause and Incidence
Allergies in dogs are the result of an oversensitive immune system and triggered by inhaling small particles such as plant pollen. Dogs with inhalant allergies are genetically programmed to become oversensitive. Purebreds are most often affected. Breeds at higher than normal risk for inhalant allergies include schnauzers, Irish setters, Boston terriers, Scottish terriers, West Highland terriers, cairn terriers, and wire-haired terriers. Signs of allergic inhalant dermatitis usually first appear at 1 to 3 years of age during the dog's second or later ragweed pollen season. Ragweed pollen season occurs from about the second week in August to the first hard frost, usually in November.
Signs
Itching of the entire body is the main sign or symptom of allergic inhalant dermatitis caused by ragweed pollen. The face, feet, and axilla ("armpits") are usually the first and most severely affected areas. Chewing, scratching, and bacterial infection damage the skin. Hair loss may eventually occur around the eyes and tops of the feet as a result of damage to the hair shafts from the severe rubbing and scratching of these areas. Occasionally, dogs with inhalant allergies will sneeze and have an itchy nose which the dog will rub excessively.
Diagnosis
Either skin or blood tests can be used to identify the cause of allergy. Your veterinarian will advise you if these tests are necessary for your dog.
Treatment
Antihistamines may be used, but are rarely very effective alone. Histamine is only one of the chemicals that are causing the itching.
Treatment with drugs that suppress the immune system and reduce inflammation (cortisone family drugs) are often the most effective means of controlling allergic inhalant dermatitis. If large doses or prolonged use of these drugs is required, the effectiveness may diminish and the adverse effects increase. A new anti-inflammatory drug (cyclosporine, "Atopica") is available which is less likely to cause adverse effects with long-term use, but it is much more expensive than cortisone-type drugs.
Desensitizing injections ("allergy shots" or immunotherapy) may help if avoidance or drug therapy is ineffective. However, desensitization is slow in becoming effective, is expensive, and some continued drug treatment is usually necessary.
Regular bathing and grooming can help control allergic inhalant dermatitis by reducing the pollen and other allergens caught in the hair coat.
Management Measures Reduce exposure - confine indoors with air conditioning, particularly at night and in the early morning hours Restrict to rooms with tile or hardwood floors Keep skin cool – clip long hair
For more information, contact your local veterinarian or the MU Veterinary Medical Teaching Hospital 573-882-7821 or visit http://www.vmth.missouri.edu/
C.B. Chastain, DVM
Professor, University of Missouri
College of Veterinary Medicine
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