Allergy Shots (Immunotherapy) for Dogs

Allergy shots for dogs is effective at giving them relief from itching and improving the quality of life.  Immunotherapy is important early in a dog’s life because environmental allergies are progressive and will worsen as a dog gets older.

Allergy Shots for Dogs

Allergy shots (Immunotherapy) for dogs are effective when dog allergies are a Type I Hypersensitivity Immune reaction.

Dog Allergies – Type I Hypersensitivity

Dog allergies are a result of a hypersensitive immune system, one which overreacts to a stimulus. The most common type of allergic reaction people see in their dogs (and in themselves) is a Type I Hypersensitivity (there are 4 Types, but for the scope of this writing, only Type I will be addressed). Allergies are basically the immune system overacting or acting inappropriately. When the body is exposed to a foreign protein like is found in a virus or bacteria, it usually makes an antibody called IgG to neutralize that foreign protein. In some animals and people, the body makes IgE instead of IgG and that is where the problem begins.

The Allergic Reaction

In the typical allergic reaction, a reactive chemical called histamine is released from granules in a cell called a mast cell. The mast cells are stimulated to release this chemical by a protein (which is actually a type of antibody) called IgE. IgE is specific for certain allergens (which are foreign proteins found in pollens, foods, molds, etc.). When the body is exposed to certain levels of specific allergens, it responds by releasing IgE specific for that allergen. The IgE then stimulates the mast cells. The mast cells in turn release histamine (“degranulate”) which causes the inflammatory reactions seen in common allergies. In people, the offending chemical IgE and mast cells, are in highest concentrations in the respiratory tract and mucous membranes (eyes, nose, mouth), but in dogs the concentration is much higher in the skin. This is why people more often have “hay fever” symptoms and dogs experience itchy skin.

An allergy is technically an immune response, therefore it requires previous exposure. This means a patient will usually not have a reaction the first time they are exposed to an allergen because the body needs time to react and make IgE. Also, in regards to food based allergies, it is possible to develop a food allergy to a food source which the patient has been eating for years. Allergies also can change with age, so the results of one test may not be the same years later as new allergies can develop with time.

Pruritic (Itch) Threshold

The idea of the pruritic (itch) threshold is that there is for every animal (or person) a level or amount of allergens (allergy inducing particles) that must be present before symptoms (itching, etc.) will occur. Every animal has a different threshold. An animal can be allergic to something in their food all year long and never show symptoms as there is not enough allergen exposure to cross the threshold; however, if they are also allergic to ragweed, then when ragweed season is in full force, they are itchy because the food allergy and the ragweed allergy when added together cross the threshold. If we are able to determine the food component and remove that food, then there is a chance that the ragweed season will not affect that pet because the threshold is no longer being crossed.

An Example of the Pruritic (Itch) Threshold in Jake the Labrador: Another way to look at it is if Jake the Labrador has a pruritic threshold of 6 (numbers strictly for illustrative purposes). Let’s now assume for Jake that beef counts as a 2 for him, wheat as a 3, and Bermuda grass as a 3. If he is eating a diet that has beef and wheat in it and he lives in a Bermuda grass dominated area (like North Texas), then his body is experiencing an allergen exposure level of 8, which is above his threshold of 6. This means he will most likely show some level of symptom all year. This may manifest in the skin or maybe only in the ears as an infection that is never totally cleared. Since we cannot remove the Bermuda grass from the environment, we can try him on desensitization injections (immune-modulating allergy shots) to reduce the effect of the Bermuda grass which may put him at an allergen exposure level of 5 which is below his threshold. Alternately, if we change his diet to something with different meat and starch sources (e.g. duck and potato) and if his numbers for these two food sources are 1 each, then he is at a level of 5, which is below his threshold even without doing anything about the Bermuda grass.

Impaired Skin Barrier Function

The impaired skin barrier function is another component of skin allergy and is related to the skin, a physical barrier protecting your dog. In allergic dogs, there is often an impairment of this barrier which allows pollens and other allergens to physically penetrate the skin deeply and stimulate the allergic response from their mere presence. This is why dogs with grass allergies often seem to have a problem primarily with their feet and that often there is some level of relief offered by covering the feet before allowing walking on the grass and/or from wiping the feet down shortly after coming inside from the grass. The exposure is not a simple inhaling issue like in people, but a physical contact issue with the skin.

Allergy Testing and Immunotherapy (Immune-Modulating Allergy Shots)

Allergy testing is the best way to find the source of some allergens to see if there is something that can be removed from the environment or diet, or if there is a specific serum that can be made for the pet in question so that they are not nearly so reactive to that allergen. Once tested, a serum or “vaccine” can be manufactured that is specific for the offending for a given patient. The idea behind this is to inject small concentrations (Immune-Modulating allergy shots) of the allergens to teach the body to make IgG instead of IgE. This Immunotherapy (Hyposensitization) can take a few months to a year before a patient responds favorably to the injections, and there are cases in which some patients never respond properly. Many people are stopped by the cost of the testing up front, but if they were to add up all financial costs of the exams, tests, pills, injections, and topical medications that they end up buying to treat the chronic skin and ear issues; plus the physical cost to their pets from the chronic inflammation, irritation, discomfort, and infections from the allergies, then testing will almost always pay for itself in the long run. Please remember that allergies also can change with age, so the results of one test may not be the same years later as new allergies can develop with time. If a patient that has been doing well on injections for a period of time develops symptoms again, it is often recommended to retest to be sure a new allergy has not developed. If one has, then the serum for the injections needs to be changed.

Breeds of Dogs with Known Pre-disposition for Allergy

Due to the hereditary nature of the disease, several breeds, including mixed breed dogs can have atopic dermatitis, especially most terriers,  Golden Retrievers, Irish Setters, Lhasa Apsos, Dalmatians, Bulldogs, and Old English Sheep dogs. Here is a comprehensive list of dogs that may inherit dog allergies:

• Boston Terrier
• Boxer
• Bull Terrier
• Cairn Terrier
• Chihuahua
• Chinese Shar-Pei
• Cocker Spaniel
• Dalmatian
• English Bulldog
• English Setter
• German Shepherd
• Golden Retriever
• Gordon Setter
• Irish Setter
• Jack Russell Terrier
• Labrador Retriever
• Lhasa Apso
• Miniature Schnauzer
• Pug
• Scottish Terrier
• Shih Tzu
• West Highland White Terrier
• Wirehaired Fox Terrier
• Yorkshire Terrier

If you suspect that your dog has allergies, please come in and see if we can help you and your pet get some relief. Please call 972-731-0001 to schedule an appointment or complete an Online Appointment Request to meet with our veterinarians at the Plantation Pet Health Center in Frisco.