Immunotherapy for Dogs: Allergy Shots and Sublingual Drops Explained

By Emiel Maddens  ·  Reviewed in consultation with licensed veterinary professionals  ·  Updated April 2026  ·  12 min read

Photo by Karsten Winegeart on Unsplash

If your dog has been battling environmental allergies for years, cycling through antihistamines, steroids, Apoquel, or Cytopoint injections, your veterinarian or dermatologist may have recommended allergen-specific immunotherapy as a longer-term strategy. Unlike medications that suppress symptoms while the dog takes them, immunotherapy aims to fundamentally change how the immune system responds to allergens. The concept is simple: by introducing tiny, gradually increasing amounts of the specific allergens your dog is sensitive to, the immune system can be retrained to tolerate those triggers rather than overreacting to them. This guide covers both delivery methods, what the treatment timeline looks like, realistic expectations for success, and how to decide if immunotherapy is the right choice for your dog.

Allergen-specific immunotherapy has been used in veterinary medicine for over four decades and remains the only treatment that modifies the underlying disease process rather than simply managing symptoms. The approach was adapted from human allergy medicine, where desensitization injections have been standard practice since the early twentieth century. In recent years, sublingual (under-the-tongue) delivery has emerged as a convenient alternative to injections, broadening access for dogs whose owners are uncomfortable with needles or whose pets resist injection protocols. Understanding the science, logistics, and realistic outcomes of both approaches empowers you to have a productive conversation with your veterinary team about whether immunotherapy belongs in your dog's long-term management plan.

What Is Allergen-Specific Immunotherapy (ASIT)?

Allergen-specific immunotherapy is a treatment protocol in which a dog receives controlled, gradually increasing doses of the specific environmental allergens identified through allergy testing. The goal is immune tolerance, a state in which the immune system no longer mounts an excessive inflammatory response upon exposure to those allergens. ASIT is available in two forms: subcutaneous immunotherapy (SCIT), which involves injections given under the skin at scheduled intervals, and sublingual immunotherapy (SLIT), which involves placing liquid drops containing allergen extracts under the tongue once or twice daily. Both methods use a customized allergen formulation based on your dog's individual allergy test results, whether those results came from intradermal testing or serum-based testing. ASIT is not a standalone cure but rather a foundational treatment that, when successful, can reduce or eliminate the need for ongoing symptom-control medications.

How Does Immunotherapy Retrain the Immune System?

The immunological mechanisms underlying desensitization are complex, but understanding the basics explains why this treatment requires months of patience and why it does not work for every dog.

The Shift from Th2 to Th1 and Regulatory T-Cell Response

In dogs with atopic dermatitis, the immune system is skewed toward a T-helper 2 (Th2) response when encountering environmental allergens. Th2 cells produce cytokines like IL-4, IL-5, and IL-13 that drive IgE production, eosinophil recruitment, and the inflammatory cascade responsible for itching and skin damage. Immunotherapy works by gradually shifting this response toward a more balanced Th1 profile and, critically, by inducing allergen-specific regulatory T-cells (Tregs). These Tregs produce anti-inflammatory cytokines such as IL-10 and TGF-beta, which actively suppress the allergic response. This immune rebalancing is why improvement is gradual rather than immediate, as the regulatory cell populations need time to expand and establish dominance over the Th2 response.

IgG4 Blocking Antibodies

As immunotherapy progresses, the immune system begins producing allergen-specific IgG4 antibodies (or the canine equivalent) that compete with IgE for allergen binding. These blocking antibodies intercept allergen molecules before they can cross-link IgE on mast cell surfaces, preventing the degranulation that releases histamine and other inflammatory mediators. Studies in both human and veterinary patients have shown that increasing levels of blocking antibodies correlate with clinical improvement during immunotherapy.

Subcutaneous Immunotherapy (SCIT): The Injection Protocol

Traditional allergy injections are given subcutaneously (under the skin) using a small-gauge needle, similar to insulin injections. The protocol consists of two phases. During the induction phase, which typically lasts 4 to 6 months, the allergen concentration and volume are gradually increased with injections given every few days to weekly. Once the target maintenance dose is reached, injections are spaced to every 2 to 4 weeks and continued indefinitely, often for life. Most owners learn to administer injections at home after initial training at the veterinary clinic, which significantly reduces the cost and inconvenience of frequent clinic visits.

Sublingual Immunotherapy (SLIT): The Drop Protocol

Sublingual immunotherapy delivers allergen extracts as a liquid pump spray or drops placed under the tongue, where they are absorbed through the oral mucosa. SLIT is typically administered once or twice daily and does not require an extended induction phase with dose escalation, though some protocols do start with a lower concentration. The oral mucosal route appears to engage a slightly different set of immune mechanisms, particularly involving dendritic cells in the sublingual tissue that promote tolerogenic immune responses. Studies comparing SCIT and SLIT in dogs show broadly similar efficacy rates, with SLIT offering the advantage of needle-free daily administration.

Timeline: Induction, Maintenance, and Expected Results

The full immunotherapy timeline requires patience. During the first 3 to 6 months (induction for SCIT, dose establishment for SLIT), most dogs show little to no improvement, which can be discouraging. Meaningful clinical improvement typically becomes apparent between months 6 and 12, with maximum benefit often not reached until 12 to 18 months. Published studies report that approximately 60 to 75 percent of dogs show clinically significant improvement, with roughly 20 to 25 percent achieving excellent responses (near-complete symptom resolution), 40 to 50 percent showing good responses (significant symptom reduction with less medication needed), and 25 to 40 percent showing minimal or no response.

Sublingual immunotherapy involves placing allergen drops under the dog's tongue daily, offering a needle-free alternative to traditional allergy injections.

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Which Breeds Benefit Most?

Breeds predisposed to atopic dermatitis are the primary candidates for immunotherapy. Since immunotherapy is only effective for environmental allergies (not food allergies), dogs with confirmed environmental sensitization through allergy testing benefit most.

• German Shepherd: German Shepherds frequently develop environmental allergies with perianal and interdigital involvement. Their large size makes long-term Apoquel or cyclosporine therapy costly, which can make immunotherapy a more economical choice over the dog's lifetime despite the slow onset of effect.
• Labrador Retriever: Labradors are among the most commonly referred breeds for immunotherapy. Their allergen profiles frequently include dust mites and storage mites, which respond particularly well to desensitization protocols. Combining immunotherapy with environmental mite-reduction strategies enhances outcomes.
• Golden Retriever: Golden Retrievers often develop moderate to severe atopy that requires lifelong management. Immunotherapy can reduce the medication burden in this breed and is frequently recommended by veterinary dermatologists as a cornerstone of their long-term management plan.
• West Highland White Terrier: Westies have a very high prevalence of atopic dermatitis and are among the breeds most commonly started on immunotherapy. Their smaller body size makes subcutaneous injections straightforward for owners to administer at home, and many Westies achieve meaningful improvement within the first year.
• French Bulldog: French Bulldogs with environmental allergies often have concurrent skin fold complications that benefit from reduced overall allergic inflammation. Immunotherapy can decrease the frequency of secondary yeast and bacterial infections in skin folds by addressing the root immune dysfunction.
• Cocker Spaniel: Cocker Spaniels commonly present with allergic otitis (ear inflammation) as a primary sign of atopy. Immunotherapy can significantly reduce the frequency and severity of ear flares in this breed when combined with appropriate ear maintenance protocols.

Conditions This Addresses

Immunotherapy is specifically designed for environmental allergies but has implications for several related skin conditions that occur secondary to or alongside atopic dermatitis.

• Canine Atopic Dermatitis: The primary and only validated indication for allergen-specific immunotherapy. ASIT targets the root cause of atopic dermatitis by retraining the immune system to tolerate environmental allergens, making it the only treatment that can potentially modify the disease course.
• Yeast Dermatitis (Malassezia): Recurrent yeast overgrowth on the skin and ears is frequently driven by underlying atopic inflammation. As immunotherapy reduces the allergic component, many dogs experience fewer yeast infections. Topical antifungal therapy from products like those in Vetified's line remains important for managing active flares.
• Recurrent Pyoderma: Bacterial skin infections that keep recurring despite appropriate antibiotic therapy often signal underlying allergic skin disease. Successful immunotherapy reduces the frequency of pyoderma episodes by restoring healthier skin barrier function.
• Flea Allergy Dermatitis: Many atopic dogs are concurrently sensitized to flea saliva. Some immunotherapy formulations can include flea allergen extract, and year-round flea prevention is essential alongside any immunotherapy protocol to minimize combined allergen burden.
• Seasonal Allergies in Dogs: Dogs with seasonal patterns to their allergies are often excellent immunotherapy candidates because their allergen triggers (specific pollens) are well defined and testable. These dogs may eventually only need immunotherapy seasonally rather than year-round.

Starting Immunotherapy: What the Process Looks Like

The road from allergy diagnosis to active immunotherapy treatment involves several steps. Understanding the full process helps you plan financially and set realistic expectations.

Step 1: Allergy Testing to Identify Triggers

Immunotherapy formulations are custom-made based on your dog's individual allergy test results. Testing can be performed through intradermal testing (IDT) at a veterinary dermatologist's office or through serum-based (blood) testing at your general veterinarian's clinic. Both methods identify which environmental allergens your dog is sensitized to. For a detailed comparison of testing methods, see our guide on dog allergy testing: intradermal vs. serum.

Step 2: Custom Formulation and Delivery Method Selection

Based on test results, your dermatologist selects the most clinically relevant allergens (typically 8 to 12) and orders a custom formulation from a veterinary allergen laboratory. You will choose between subcutaneous injections and sublingual drops based on your comfort level, your dog's temperament, and your veterinarian's recommendation. Both methods have similar efficacy, so the choice largely comes down to practicality and preference.

Step 3: Induction Phase (Months 1 to 6)

For subcutaneous immunotherapy, the induction phase involves gradually increasing injection doses and volumes over approximately 4 to 6 months, with injections given every 2 to 7 days depending on the protocol. Your veterinarian will teach you to administer injections at home. For sublingual immunotherapy, treatment typically starts at the prescribed dose from day one, with drops given once or twice daily. During induction, your dog will likely still need concurrent allergy medications to manage symptoms.

Step 4: Maintenance Phase (Month 6 Onward)

Once the target dose is reached with SCIT, injections are spaced to every 2 to 4 weeks and continued indefinitely. SLIT continues at the same daily frequency. The maintenance phase is when most dogs begin showing clinical improvement. Your veterinarian will schedule follow-up appointments every 3 to 6 months to assess response, adjust the protocol if needed, and potentially reduce concurrent medications as immunotherapy takes effect.

Step 5: Long-Term Management and Protocol Adjustments

Immunotherapy is typically a lifelong commitment. If the initial formulation provides partial but incomplete improvement, your dermatologist may adjust the allergen concentrations, add or remove specific allergens, switch from SCIT to SLIT (or vice versa), or modify the dosing interval. Some dogs achieve such good control that maintenance injections can be spaced to monthly with no loss of efficacy, while others require more frequent dosing to maintain benefit.

Signs of Improvement and How to Measure Progress

Because immunotherapy works gradually, tracking your dog's symptoms over months is essential for assessing whether the treatment is effective. Small improvements can be easy to miss without systematic observation.

Decreasing Medication Requirements

One of the earliest measurable signs of immunotherapy success is a reduced need for concurrent allergy medications. If your dog previously needed Apoquel daily and can now skip days without flaring, or if Cytopoint injections are lasting longer between doses, immunotherapy is likely contributing to improved baseline control.

Longer Intervals Between Flares

Rather than looking for complete symptom resolution (which is uncommon), track the frequency and severity of flare episodes. A dog that previously flared every two weeks and now flares every six weeks is showing meaningful improvement, even if flares still occur. Keeping a simple calendar log of flare days helps quantify this progress.

Reduction in Secondary Infections

Dogs responding to immunotherapy often experience fewer secondary bacterial and yeast skin infections over time. If your veterinarian used to see your dog for skin infections every month and visits have become quarterly, this represents a significant quality-of-life improvement and indicates better underlying immune regulation.

Improved Coat and Skin Quality

Gradual improvements in coat fullness, skin texture, and reduced hyperpigmentation (darkened skin) are later signs that immunotherapy is working. These changes typically lag behind itch reduction by several weeks to months, as the skin needs time to heal and regenerate after chronic inflammation.

Potential Side Effects and Risks

Immunotherapy is one of the safest long-term allergy treatments available, but there are potential downsides and limitations that pet owners should understand before beginning the commitment.

Injection Site Reactions

Some dogs experience mild swelling, redness, or itching at the subcutaneous injection site. These local reactions are usually self-limiting and resolve within a few hours. Applying a cool compress can provide comfort. Persistent or worsening injection site reactions should be reported to your veterinarian, as the dose or concentration may need adjustment.

Temporary Worsening of Symptoms

A small percentage of dogs experience a temporary increase in allergy symptoms during the induction phase, particularly when allergen doses are being escalated. This occurs because the immune system is being actively stimulated with the very substances it is allergic to. Your veterinarian can manage this by slowing the dose escalation, temporarily reducing the dose, or prescribing short-term symptom-control medications.

Rare Systemic Allergic Reactions

Anaphylactic reactions to immunotherapy injections are rare but possible. Signs include facial swelling, hives, vomiting, diarrhea, difficulty breathing, or collapse occurring within minutes to hours of an injection. This is why first injections at new dose levels are sometimes administered at the veterinary clinic with a 30-minute observation period. Owners administering injections at home should be familiar with these signs and have emergency contact information readily accessible.

Treatment Failure: The 25 to 40 Percent Non-Response Rate

Not every dog responds to immunotherapy. Approximately 25 to 40 percent of dogs show minimal or no improvement after a full 12-month course. Factors that may influence response include the accuracy of the allergy test results, whether all relevant allergens were included in the formulation, concurrent untreated food allergies, and individual variation in immune responsiveness. Non-responding dogs still have other effective management options including Apoquel, Cytopoint, cyclosporine, and multimodal topical care.

Time and Financial Investment Without Guaranteed Returns

The combination of allergy testing ($200 to $600), immunotherapy formulation ($200 to $400 for the initial vials), and ongoing monthly costs ($50 to $150) represents a significant investment, especially given that results take 6 to 12 months to materialize. However, for dogs that respond well, the long-term cost of maintenance immunotherapy is often lower than ongoing Apoquel or Cytopoint therapy, making it a potentially cost-effective strategy over the dog's lifetime.

When to See Your Vet Instead

Immunotherapy requires veterinary oversight at every stage, from allergy testing through ongoing maintenance. Certain situations warrant prompt communication with your veterinary team.

Suspected Allergic Reaction After an Injection

If your dog develops facial swelling, widespread hives, vomiting, lethargy, or difficulty breathing within minutes to hours of a subcutaneous injection, seek emergency veterinary care immediately. While systemic reactions are rare (estimated at less than 1 percent of injection visits), they require prompt treatment with epinephrine, antihistamines, and supportive care.

No Improvement After 12 Months of Consistent Therapy

If your dog has been receiving immunotherapy consistently for a full year with no discernible improvement in symptoms, medication requirements, or infection frequency, schedule a reassessment with your dermatologist. Options include reformulating the allergen mix, switching delivery methods (SCIT to SLIT or vice versa), retesting for additional allergens, or transitioning to a different management strategy.

Significant Change in Symptom Pattern

If your dog develops new symptoms or a dramatically different distribution of skin disease during immunotherapy, a veterinary evaluation is important. New patterns could indicate development of additional allergen sensitivities, emergence of a concurrent condition such as food allergy or hypothyroidism, or secondary complications requiring separate treatment.

Related Symptoms

Dogs undergoing this treatment often present with these symptoms. Our guides explain each one:

• Dog Scratching at Night, Nighttime scratching driven by dust mite sensitivity is one of the most common symptoms that leads to immunotherapy referrals, as dust mites are among the most successfully targeted allergens.
• Recurring Dog Ear Infections, Chronic allergic otitis is a frequent manifestation of atopic dermatitis, and many dogs see significant reductions in ear infection frequency as immunotherapy takes effect.
• Excessive Paw Licking in Dogs, Interdigital itching from environmental allergens often improves with successful immunotherapy, particularly when grass or weed pollens are among the identified triggers.
• Dog Yeasty Smell, The characteristic musty odor of Malassezia overgrowth often decreases as immunotherapy controls the underlying allergic inflammation that promotes yeast proliferation.
• Dog Hair Loss and Thinning Coat, Alopecia from chronic scratching and inflammation can gradually resolve as immunotherapy reduces the allergic itch cycle, though full regrowth may take several months.

Frequently Asked Questions About Immunotherapy for Dogs

Q: How much does immunotherapy cost for dogs?

Initial costs include allergy testing ($200 to $600) and the first immunotherapy vial ($200 to $400). Ongoing monthly costs for maintenance therapy typically range from $50 to $150 depending on the formulation and whether you administer injections at home or visit the clinic. Over a dog's lifetime, immunotherapy is often less expensive than continuous Apoquel (approximately $2 to $3 per day) or Cytopoint ($50 to $150 per injection every 4 to 8 weeks).

Q: How long does immunotherapy take to work in dogs?

Most dogs require 6 to 12 months of consistent therapy before clinically significant improvement is visible. Some dogs show early improvement within 3 to 4 months, while others may not reach maximum benefit until 12 to 18 months. The slow timeline reflects the gradual immunological retraining process and is not an indication that the treatment is failing.

Q: What is the success rate of immunotherapy in dogs?

Published veterinary studies consistently report that approximately 60 to 75 percent of dogs show meaningful improvement with allergen-specific immunotherapy. About 20 to 25 percent achieve excellent results with near-complete symptom resolution, 40 to 50 percent show good improvement with reduced medication needs, and 25 to 40 percent show minimal or no response.

Q: Are allergy shots or sublingual drops better for dogs?

Clinical studies show broadly similar efficacy between subcutaneous (injection) and sublingual (drop) immunotherapy. The choice often depends on practical factors: owners comfortable with needles may prefer the less frequent injection schedule, while those who prefer a needle-free approach may opt for daily sublingual drops. Some dogs that do not respond to one delivery method may improve when switched to the other.

Q: Can immunotherapy cure my dog's allergies?

Immunotherapy does not cure allergies in the traditional sense, but it can significantly reduce the immune system's overreaction to specific allergens, sometimes to the point where the dog requires little or no additional medication. Most veterinary dermatologists consider it a long-term management strategy rather than a cure, as discontinuation can lead to gradual relapse in some dogs.

Q: What happens if immunotherapy does not work for my dog?

If your dog shows no improvement after 12 months of consistent immunotherapy, your dermatologist may recommend reformulating the allergen mix, switching from injections to drops (or vice versa), retesting for additional allergens, or transitioning to other management strategies such as cyclosporine, Apoquel, or Cytopoint. Multimodal management including medicated bathing and omega-3 supplementation remains important regardless of immunotherapy response.

Q: Does my dog need allergy testing before starting immunotherapy?

Yes. Immunotherapy formulations are custom-made based on the specific allergens your dog is sensitized to, so allergy testing (intradermal or serum-based) is a mandatory prerequisite. There is no standardized, one-size-fits-all immunotherapy product. Testing identifies which of the dozens of potential environmental allergens should be included in your dog's unique formulation.

Sources

Olivry T, DeBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Veterinary Research. 2015;11:210.

DeBoer DJ, Morris M. Multicentre open trial demonstrates efficacy of sublingual immunotherapy in canine atopic dermatitis. Veterinary Dermatology. 2012;23(1):65-e16.

Loewenstein C, Mueller RS. A review of allergen-specific immunotherapy in human and veterinary medicine. Veterinary Dermatology. 2009;20(2):84-98.

Willemse A, Van den Brom WE, Rijnberk A. Effect of hyposensitization on atopic dermatitis in dogs. Journal of the American Veterinary Medical Association. 1984;184(10):1277-1280.

Mueller RS, Bettenay SV. Evaluation of the safety of an abbreviated course of injections of allergen extracts (rush immunotherapy) for the treatment of dogs with atopic dermatitis. American Journal of Veterinary Research. 2001;62(3):307-310.

Bentley JL, DeBoer DJ. Sublingual immunotherapy for atopic dermatitis in dogs: a prospective pilot study. Veterinary Dermatology. 2014;25(5):463-e75.

Related Reading

• Dog Allergy Testing: Intradermal vs. Serum Testing, Allergy testing is a mandatory prerequisite for immunotherapy. This guide compares the two testing methods to help you understand which approach best identifies your dog's triggers.
• Canine Atopic Dermatitis: Complete Guide, Comprehensive overview of the allergic skin disease that immunotherapy is designed to treat, including diagnosis criteria and the full range of management options.
• When to See a Veterinary Dermatologist, Immunotherapy is typically initiated and monitored by veterinary dermatologists. Learn when a specialist referral is warranted for your dog's skin condition.
• Natural Allergy Relief for Dogs, Complementary approaches including fatty acids, probiotics, and environmental management strategies that can enhance immunotherapy outcomes.
• Elimination Diets for Dogs: A Step-by-Step Guide, Since immunotherapy only addresses environmental allergies, ruling out food allergies through an elimination diet is an important parallel step in comprehensive allergy management.
• Chlorhexidine for Dogs: Veterinary Antiseptic Guide, Topical antimicrobial care with chlorhexidine remains an essential part of managing secondary infections during the months before immunotherapy reaches full effect.

Emiel Maddens

Founder of Vetified. Develops topical antifungal and antimicrobial formulations for companion animals. Vetified products are listed on DailyMed and manufactured through FDA-registered facilities in the United States.