Allergy shots, formally known as Subcutaneous Immunotherapy (SCIT), offer a long-term treatment option for individuals with persistent allergic reactions to dogs. These allergies are caused by specific proteins found primarily in the animal’s dander, saliva, and urine, not the hair. The immune system mistakenly identifies these harmless proteins as threats, triggering an inflammatory response that causes symptoms like sneezing, congestion, and asthma. SCIT modifies this immune response, aiming for tolerance rather than simply masking symptoms with medication. This treatment involves a significant time commitment, but it can be the most effective way to live comfortably alongside a canine.
Confirming Sensitivity to Dog Allergens
A precise diagnosis is mandatory before starting immunotherapy to confirm that dog allergens are the source of symptoms. Allergists typically use two primary methods: skin prick tests and specific IgE blood tests. The skin prick test involves introducing minute amounts of dog dander extract beneath the skin to observe a localized reaction. A positive result, indicated by a raised bump or wheal, suggests the presence of allergen-specific antibodies.
Alternatively, a blood test, sometimes called a RAST or ImmunoCAP test, measures the concentration of Immunoglobulin E (IgE) antibodies specific to dog allergens circulating in the bloodstream. Modern testing often includes component-resolved diagnostics, which identify sensitivity to specific proteins like Can f 1 (the most common dog allergen) or Can f 5 (associated with male dogs). Pinpointing the exact allergenic protein ensures the immunotherapy treatment is custom-formulated and highly targeted.
How Allergy Shots Retrain the Immune System
Allergy shots work by introducing gradually increasing doses of the dog allergen extract into the body, systematically modifying the aggressive immune response. This therapeutic exposure forces the immune system to shift away from the allergic reaction pathway dominated by T helper 2 (Th2) cells. Th2 cells promote the production of IgE antibodies, which bind to mast cells and trigger histamine release upon allergen re-exposure.
The goal of SCIT is to induce immunologic tolerance by steering the response toward a different pathway. This involves stimulating regulatory T-cells (Tregs), which secrete anti-inflammatory molecules such as Interleukin-10 (IL-10) and Transforming Growth Factor-beta (TGF-beta). These molecules actively suppress the inflammatory Th2 cells, reducing overall allergic sensitivity. The treatment also stimulates B-cells to produce protective antibodies, specifically Immunoglobulin G (IgG), particularly the IgG4 subtype. These “blocking antibodies” intercept dog allergens before they can bind to IgE antibodies, preventing the allergic cascade and reducing symptoms.
The Immunotherapy Timeline and Long-Term Outcomes
Allergen immunotherapy for dog allergies is a long-term commitment divided into two distinct phases.
Build-Up Phase
The build-up phase involves frequent injections, often once or twice a week, with a steadily escalating concentration of the allergen extract. This phase typically lasts between three and six months. Its purpose is to condition the immune system to tolerate high levels of the allergen.
Maintenance Phase
Once the highest tolerated dose is reached, patients transition into the maintenance phase. Injection frequency decreases significantly, usually to every two to four weeks. This phase must be sustained for three to five years to ensure long-lasting tolerance. Symptom relief often begins during this period, sometimes taking six to twelve months to become noticeable.
SCIT offers a high efficacy rate for environmental allergens, including dog dander, with most patients experiencing a significant reduction in symptoms and reliance on allergy medications. The benefit of this long-term treatment often persists for years after the injections are stopped. However, discontinuing the treatment too early increases the risk of the allergic sensitivity returning.