Once an animal has been diagnosed with allergic skin disease due to inhalant or environmental allergies, allergy vaccines (allergen specific immunotherapy) may be suggested as part of the management of the pet's condition. Although this is not a cure for the skin condition, it is part of the management strategy to keep the animal's allergic condition under control, thus leading to healthier skin and minimizing the discomfort caused by the severe pruritus (itching) associated with the allergic reaction.

How Allergen Extracts Work

  • Hyposensitization (allergy vaccine) is an attempt to induce immunologic tolerance to allergens that currently cause allergic symptoms.

  • The rate in which an animal may respond to allergy vaccine is quite varied and may take up to 6 months or even a year to build up enough “protective” (IgG) antibodies to eliminate the allergic symptoms.

  • Hyposensitization is not a “cure” for allergies. Maintenance injections must be continued for the life of the pet. The interval between injections will vary with each animal but is generally given on a monthly basis once a good clinical response is achieved.  DO NOT STOP THE VACCINE UNLESS YOU AND YOUR VETERINARIAN DECIDE THAT HYPOSENSITIZATION IS NOT ACCCEPTABLE FOR YOUR PET. 

Routes of Administration

There are two routes of administration - injections and oral (sublingual immunotherapy)

Technique for Subcutaneous Injections 
(under the skin)

  • The vaccine should be kept refrigerated.

  • Syringes and needles are disposable and should only be used once. The used syringes and needles can be returned to your veterinarian for safe disposal as medical waste.

  • Insert the needle underneath the skin over the neck, shoulder or back area. Once in position, push the plunger and release the contents under the skin. Pull the needle out of the skin and discard. Vary your injection sites to minimize pain.

  • Try to adhere to the suggested schedule of injections recommended by your veterinarian.

  • Only give the injection if you will be able to watch your pet for at least one hour after the injection is given - to monitor for any adverse reactions.

Sublingual Immunotherapy
- involves giving “allergy drops” twice daily. This form of vaccine administration is as equally effective as the injectable form.

Adverse Reactions & Side Effects

  • Reactions to allergy vaccine are rare.

  • There may be mild itchiness or irritation at the injection site for a few minutes after the injection.

  • During the early stages of hyposensitization an increase in itchiness is common for one or two days after the injection. If this is a problem for your pet, you may need to use topical therapy or antihistamines to help minimize the clinical signs.

  • The most severe reaction is anaphylactic shock. Your pet is slowly being given very small amounts of allergens to help prevent this occurrence. If anaphylaxis occurs, it will manifest within 30 minutes to one hour after the injection is given. This severe reaction will appear as vomiting, diarrhea, generalized hives, swollen face, and / or difficulty breathing and weakness. Take your pet to a veterinarian immediately. This reaction is extremely rare.

Interactions with other medications and vaccines

  • Allergy vaccines will not interfere with other routine vaccines (Distemper, Parvo, Rabies, etc.)

  • Large doses of prednisone or other corticosteroids may decrease or retard the effectiveness of the vaccine and should therefore be avoided if at all possible. Low doses are certainly acceptable if needed.

Other Important Considerations

Bacterial Infections

  • Bacterial infections can contribute to your pet’s itchiness. 

  • Superficial pyoderma (bacterial folliculitis) is an infection of the skin and hair follicles recognized by the appearance of a rash, pimples, pustules, scabs, and “hot spots.”

  • In certain short-coated breeds, these infections can appear merely as patches of circular hair loss.

  • Staphylococcus pseudintermedius (Staph infection) is the frequent cause of this condition and is often seen in association with allergies.

  • Staphylococcal bacteria are part of the normal flora of the skin and are thus not considered contagious to you or other pets in the household.

  • Shampoo therapy and, often, oral antibiotics are needed to control superficial pyoderma in allergic patients.

Flea Control

  • Flea control is vitally important for the allergic pet.

  • Fleas do not need to be seen for them to be considered a contributing factor in the pet’s itchiness.

  • A flea allergic pet generally does not have a severe flea infestation. Rather, it is a massive reaction to the saliva of the flea.

Yeast Infection

  • Malassezia pachydermatis (yeast) overgrowth is a common cutaneous opportunist in allergic patients.

  • The organism may colonize the skin and / or ear canal.

  • Allergic patients produce excessive amounts of wax in the ear canal which is conducive to yeast and bacterial overgrowth.

  • Yeast organisms may cause excessive pruritus (itchiness) and skin inflammation.

  • These organisms are not contagious to you or other pets in the household. 

Key Considerations

  • Hyposensitization is considered a component or an integral part in controlling the pet's allergic symptoms.

  • Shampoo therapy should be part of the routine maintenance protocol.

  • Antihistamines or other medications may still be necessary to control itchiness.

  • Hyposensitization is effective in approximately 75% of all tested patients. Vaccine therapy should be continued for at least one year before results can be evaluated.

  • Contact your veterinarian if you have any questions or problems with your pet. A re-check appointment is generally recommended 2 - 3 months into the vaccine protocol.

  • Vaccines should be kept refrigerated ... do not freeze!

  • It is not harmful to the vaccine if kept at room temperature for several days but do note that extreme heat and cold should be avoided.


Contributed by: Karen Helton-Rhodes, DVM, Diplomate ACVD