Cytopoint (lokivetmab) is a caninized monoclonal antibody injection that targets interleukin-31 (IL-31), one of the main chemical messengers driving allergic itch in dogs. It is administered by a veterinarian as a subcutaneous injection, and a single dose can control pruritus for 4 to 8 weeks. This article explains how Cytopoint works, who it is for, what the evidence says about efficacy and safety, when it stops working, and how it compares to other allergy medications like Apoquel.

Quick answer

Cytopoint is an injectable biologic — not a drug in the traditional sense — that binds and neutralizes canine IL-31, a cytokine that sends itch signals to the brain. It is licensed by the USDA Center for Veterinary Biologics (CVB) for the control of clinical signs associated with allergic dermatitis and atopic dermatitis in dogs. A single subcutaneous injection starts working within 1 day and lasts 4 to 8 weeks. Clinical studies show that approximately 65% of dogs respond to the first injection, with cumulative response rates reaching 85–93% after a second or third injection. Cytopoint is approved for dogs only — not cats.

How Cytopoint works

Lokivetmab is a caninized monoclonal antibody — a protein engineered to bind specifically to canine IL-31. In dogs with allergic dermatitis, environmental allergens (pollen, dust mites, mold) trigger an immune cascade that includes overproduction of IL-31. This cytokine binds to receptors in the nervous system and sends a strong itch signal to the brain, causing the scratching, licking, and chewing that damage the skin further.

Cytopoint intercepts IL-31 before it can bind to its receptor. By neutralizing soluble IL-31 in circulation, the itch signal is reduced. Because lokivetmab is a naturally derived protein rather than a small-molecule chemical, it is broken down and recycled by the body through normal protein degradation pathways — it does not rely on liver or kidney metabolism for clearance.

The half-life of lokivetmab is approximately 16 days, which explains why a single injection can provide relief for 4 to 8 weeks.

When veterinarians use Cytopoint

Cytopoint is used for dogs with:

• Atopic dermatitis — chronic, non-seasonal or seasonal allergic skin disease triggered by environmental allergens.
• Allergic dermatitis — broader pruritic skin conditions where allergic inflammation is the primary driver.

Board-certified veterinary dermatologists note that Cytopoint works best when given early in the allergic flare, when IL-31 levels are rising. In dogs that arrive at the clinic already inflamed and self-traumatized, veterinarians sometimes pair the Cytopoint injection with a short course of steroids or other anti-inflammatory therapy to bring the acute inflammation under control while waiting for the biologic to reach full effect.

Cytopoint does not treat the underlying allergy — it controls the itch signal. Identifying and managing the underlying cause (flea allergy, food allergy, environmental allergy) remains essential for long-term management.

Dosing and administration

Cytopoint is administered by a veterinarian as a subcutaneous injection. The dose is weight-based, using pre-filled vials according to a dosing chart:

The U.S. label minimum dose is 2 mg/kg. The EU label minimum dose is 1 mg/kg.

After the first injection, owners typically observe reduced itch within 1 to 3 days. A progress exam at 4 weeks is recommended to assess response and determine whether the injection interval should be adjusted. Some dogs need injections every 4 weeks; others can go 6 to 8 weeks between doses.

How well does it work

Clinical evidence from multiple studies shows:

• 65% of dogs achieved treatment success (significant pruritus reduction) after the first injection by day 30.
• 85% cumulative response by day 60 (after a second injection in dogs that needed it).
• 93% cumulative response by day 90 (after a third injection where indicated).
• In a separate European university study, 76.5% of dogs showed significant pruritus reduction and 77.8% showed significant lesion improvement over 8 weeks, with no reported adverse side effects or changes in blood tests.
• Three months after the end of that study, 77.8% of dogs continued lokivetmab therapy.

These numbers mean that most dogs respond, but not all dogs respond to the first injection. Dogs that show even a partial response to the first dose often achieve better control with a second or third injection, possibly due to antibody accumulation over the first few doses.

A veterinary dermatologist quoted by the AKC estimates Cytopoint works for about 60–65% of itchy dogs, and notes that if the injection does not provide at least 3 weeks of relief, it is likely not the best option for that individual dog.

Safety and side effects

In clinical field studies, dogs receiving Cytopoint had no more side effects than dogs receiving a placebo injection. The Zoetis product information lists the following based on voluntary post-approval reporting:

Common (generally mild):

• Lethargy for 1–2 days after injection
• Mild vomiting or diarrhea (uncommon)

Rare (fewer than 1 in 10,000 treated dogs):

• Hypersensitivity reactions: anaphylaxis, facial edema, urticaria (hives). These require immediate veterinary treatment.
• Neurological signs: seizure or ataxia (very rare).
• Immune-mediated disease: immune-mediated hemolytic anemia (IMHA) or immune-mediated thrombocytopenia (very rare).

Cytopoint is considered safe for dogs of any age and has been used alongside commonly prescribed medications — including parasiticides, antibiotics, antifungals, corticosteroids, NSAIDs, vaccines, immunotherapy, and antihistamines — without reported drug interactions in clinical studies.

Pregnancy and lactation: Safety has not been specifically established. The Zoetis product information and VCA note that it should be used with caution in pregnant or nursing dogs.

Vaccinations: Cytopoint can be given at the same time as vaccines, but the injection should be administered at a different body site.

When Cytopoint stops working

The product label warns that lokivetmab may induce anti-drug antibodies. In uncommon cases, these antibodies can be persistent and cause a noticeable decrease in efficacy in dogs that previously responded. An estimated 2.5% or less of treated dogs develop this response.

Signs that anti-drug antibodies may be developing:

• The interval between injections shortens over time (e.g., from 8 weeks to 4 weeks, then 3 weeks).
• A dog that previously responded well stops responding at all.

If this happens, veterinarians typically switch to an alternative therapy — Apoquel (oclacitinib), Zenrelia (ilunocitinib), Atopica (cyclosporine), or immunotherapy. A 2025 retrospective study described dogs receiving combination oclacitinib plus lokivetmab after monotherapy failure, suggesting that layered approaches are sometimes used under specialist guidance for refractory cases.

Cytopoint versus Apoquel

Both Cytopoint and Apoquel (oclacitinib) are used to control allergic itch in dogs, but they work differently:

The choice between Cytopoint and Apoquel depends on the dog's specific situation, comorbidities, the owner's ability to administer daily medication, and cost. Some dogs respond to one but not the other.

Dogs that may not be ideal candidates

Cytopoint may not be the best fit for:

• Dogs whose itch is not primarily IL-31 driven (some dogs with deep secondary infections, food allergy without atopic component, or parasitic dermatitis may not respond).
• Dogs that need immediate, same-day itch control and cannot wait 1–3 days for onset.
• Dogs in which injection-based therapy is impractical due to access or cost.

What to ask your veterinarian

• Is my dog's itch primarily allergic in origin? Cytopoint targets allergic itch. If the cause is parasitic, infectious, or behavioral, the injection may not help.
• How many injections should we try before deciding it is not working? Most dermatologists recommend at least 2 injections before concluding it is not the right fit, since cumulative response improves with repeated dosing.
• Should we track itch between injections? Keeping a simple log of scratching, licking, and sleep quality helps your veterinarian adjust the injection interval.
• What is the plan if Cytopoint stops working over time? Discussing backup options (Apoquel, Zenrelia, immunotherapy) before anti-drug antibodies develop avoids gaps in itch control.

Sources

• Zoetis. Cytopoint (lokivetmab) Product Information (U.S.). https://www.zoetisus.com/content/_assets/docs/vmips/package-inserts/cytopoint-product-information.pdf
• Zoetis Petcare. Cytopoint for Pet Owners. https://www.zoetispetcare.com/products/cytopoint
• Michels GM, Ramsey DS, Walsh KF, et al. A blinded, randomized, placebo-controlled, dose determination trial of lokivetmab, a caninized, anti-canine IL-31 monoclonal antibody in client-owned dogs with atopic dermatitis. Vet Dermatol. 2016;27(6):478-e129. https://pubmed.ncbi.nlm.nih.gov/27625369/
• University of Lisbon. Efficacy and safety of lokivetmab (Cytopoint) for the control of pruritus and skin lesions in dogs with atopic dermatitis. https://researchportal.ulisboa.pt/en/publications/efficacy-and-safety-of-lokivetmab-cytopoint-for-the-control-of-pr/
• Zoetis. Some Dogs Benefit from Additional Cytopoint Injections for Maximum Response (clinical data summary). https://www.zoetisus.com/content/_assets/docs/PDFs/ZPN/Cytopoint-Clinical-Applications-Advertorial.pdf
• Van Brussel. A masked, randomised clinical trial evaluating the efficacy and safety of lokivetmab compared to saline control in client-owned dogs with allergic dermatitis. PubMed Central. 2021.
• Bachtel. Efficacy of Combination Oclacitinib and Lokivetmab Therapies After Monotherapeutic Failure in 44 Dogs: A Retrospective Study. PubMed. 2025.
• VCA Animal Hospitals. Lokivetmab (Cytopoint). https://vcahospitals.com/know-your-pet/lokivetmab
• PetMD. Cytopoint Injection for Dogs. https://www.petmd.com/pet-medication/cytopoint-for-dogs
• AKC. Cytopoint for Dogs: Uses, Side Effects, and Alternatives. https://www.akc.org/expert-advice/health/cytopoint-for-dogs/