Immune Suppressant Therapy for Allergies in Dogs

Like people, dogs can suffer from allergic reactions to food and to their environment. Controlling these allergies may require medications, such as antihistamines. However, another approach for coping with allergies is immunosuppressant therapy. As the name suggests, the therapy stops the dog’s immune system from working too efficiently thus stopping the allergic reactions.

Allergic reactions in humans and canines are caused by a hypersensitive reaction in the immune system. The immune system normally reacts when bacteria, viruses, or other unwanted pathogens enter the body. The immune system produces antibodies that try to drive out the unwanted invaders resulting in allergy systems. In some cases, however, the immune system reacts to ordinary intruders, such as pollen or peanut dust, in the same way. Essentially, allergy systems are the body’s efforts to eliminate the false threat posed by those allergens – the ordinary substances that generate the false alarm in the immune system.

Because allergic reactions are caused by an overly sensitive immune system, suppressing the immune system is one way of dealing with allergies. A number of medications are available that can suppress the immune response to allergens. Steroids given in high doses can serve this function. Cyclosporine also acts as an immune suppressant. These drugs act in different ways to prevent the immune system from reacting to the presence of allergens, as well as legitimate pathogens. The drugs need to be used under the care of a veterinarian because the combination of these drugs and/or their prolonged use can cause serious side effects.

Steroids can cause serious side effects for dogs, including weight gain, diarrhea, hyperactivity and depression. These side effects can appear even when the drugs are used in small amounts over short periods of time. However, long-term effects of the drug can cause liver problems, diabetes and increased infections in dogs. The risks can be reduced by using steroids topically instead of orally, but that approach may not work for all types of allergic reactions, according to Richard Palmquist, DVM, for the Huffington Post. On the other hand, cyclosporine and similar drugs cause digestive distress in 15 to 25 percent of dogs. Some research also suggests a link between these drugs and canine cancer, Palmquist advises.

While immunosuppressant therapy is one way to fight canine allergic reactions, other options are also available and may be safer. Some allergic reactions can be prevented through avoidance. For example, if a dog has an allergy to certain food ingredients, a change in diet may solve the problem without the use of medications. Hyposensitization can also be used to reduce the dog's sensitivity to the allergen through repeated exposure. Once the specific allergen is identified through testing, an injection of altered allergens is administered over several weeks or months to slowly desensitize the dog's immune system. Although expensive and time-consuming, this treatment has a 70 to 80 percent success rate, according to the Pet Education website.