# Ivermectin for Dogs With Cancer or Lymphoma Ivermectin for dogs with cancer is not an approved or proven cancer treatment. Laboratory studies have looked at whether it can kill cancer cells, but there are no veterinary clinical trials showing it helps dogs with lymphoma or other cancers. Giving it outside a veterinarian's supervision can cause serious neurological toxicity. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Ivermectin is an antiparasitic drug. Its proven use in dogs is against parasites, not cancer [1]. - No published veterinary clinical trial shows ivermectin treats lymphoma or extends survival in dogs with cancer. - The one canine cancer trial involving ivermectin studied transmissible venereal tumor, a sexually transmitted tumor unrelated to lymphoma, and results were inconsistent [2]. - Ivermectin can cause neurological toxicity, including tremors, incoordination, and coma, especially in dogs with certain genetic mutations or at high doses [3]. - Do not give ivermectin to a dog with cancer without talking to your veterinary oncologist first. ## What Ivermectin Is and What Veterinarians Actually Use It For Ivermectin is a macrocyclic lactone, a class of drugs that has been used for decades to treat parasites in animals and people [3]. In dogs, veterinarians prescribe it to prevent heartworm disease and to treat certain mite and worm infections. It works by interfering with nerve signaling in parasites, which paralyzes and kills them [1]. The drug has a long-standing reputation for safety when used at approved doses for approved reasons [3]. That safety record is one reason it is so widely used. It is also one reason some owners wonder whether it could do more, including fighting cancer. That question has grown partly because of research into ivermectin's other possible effects. Some laboratory and preclinical work has explored antiviral activity, but those findings are exploratory and come mostly from cell cultures or early animal studies, not from treated patients [1]. The same is true for cancer. Cell-level activity does not automatically translate into a benefit in a living dog with a real tumor. ## Does Ivermectin Help Dogs With Cancer or Lymphoma? This is the central question, and the honest answer is that we do not have the evidence to say yes. For canine lymphoma specifically, there is no published clinical trial showing that ivermectin improves remission rates, extends survival, or improves quality of life. What exists for lymphoma is preclinical work on entirely different drugs. One study tested a compound called KPT-335 (Verdinexor) alone and combined with doxorubicin or vincristine in four canine lymphoma cell lines, and it found that the combinations suppressed cell growth more than single agents [4]. That is laboratory evidence about a different drug, not evidence about ivermectin. It shows how early most of this research is. The closest thing to a canine cancer trial involving ivermectin comes from transmissible venereal tumor (CTVT), which is not lymphoma. In that randomized, placebo-controlled, double-blinded trial, 20 dogs with CTVT received either vincristine alone or vincristine plus ivermectin, and researchers classified tumors as aggressive or non-aggressive [2]. The authors noted that earlier results combining the two drugs had been inconsistent, and they hypothesized that ivermectin's effect might depend on how aggressive the tumor was [2]. This is a narrow, specific cancer type. Even if the trial had shown a clear benefit, it would not tell us whether ivermectin helps a dog with lymphoma, mast cell tumor, osteosarcoma, or any other common cancer. If your dog has lymphoma, the treatments with real supporting evidence are chemotherapy protocols such as CHOP, and in some situations prednisone palliation. You can read more about how those compare in [Lymphoma in Dogs: CHOP Chemotherapy Protocol vs Prednisone Palliation](/knowledge/veterinary-medicine/dermatology-oncology/lymphoma-in-dogs-chop-chemotherapy-protocol-vs-prednisone-palliation) and about how lymphoma is diagnosed and staged in [Canine Lymphoma: Diagnosis and Chemotherapy Protocols](/knowledge/veterinary-medicine/clinical-methods/canine-lymphoma-diagnosis-chemotherapy-protocols). ## How Ivermectin Works Ivermectin's main antiparasitic effect happens through glutamate-gated chloride channels in invertebrates. The drug opens these channels, chloride flows in, and the parasite's nervous system is paralyzed [1]. Dogs do not have the same glutamate-gated chloride channels in the same places, which is part of why the drug is normally well tolerated at correct doses. The proposed anticancer mechanism is different. In laboratory settings, ivermectin has been studied for effects on cell signaling pathways that influence how cancer cells grow and die. These are test-tube findings. Whether the drug reaches a tumor in a living dog at a concentration high enough to matter, without also reaching the brain at a toxic concentration, is not well established in veterinary research. There is also a practical barrier. Ivermectin does not cross into the central nervous system easily in most dogs because of a pump called P-glycoprotein that pushes it back out. When that pump is blocked or absent, brain levels rise and toxicity becomes much more likely [5]. A study in beagle dogs found that a P-glycoprotein inhibitor changed how the drug was handled by the body [5]. This is a warning sign, not a green light. ## Dosing Basics: Who Decides and How It Is Given The dose is always set by your veterinarian. It depends on your dog's weight, the condition being treated, the formulation of the drug, and your dog's overall health. There is no safe home dose for cancer, because no cancer dose has been established for dogs. In the CTVT trial, dogs received ivermectin at 0.5 mg/kg subcutaneously, given twice, alongside weekly vincristine at 0.5 mg/m2 intravenously [2]. Those numbers come from a controlled research setting with monitoring, and they apply only to that specific tumor and protocol. They are not a recipe for treating your dog at home. Ivermectin for dogs comes in several forms, including oral tablets, chewables, and injectable products. Many over-the-counter products combine ivermectin with other drugs, and some of those combinations are dangerous for dogs. Never use a livestock or farm-supply ivermectin product on a dog. The concentrations are designed for animals weighing hundreds of pounds, and dosing errors are easy to make. If your veterinarian has prescribed ivermectin for a legitimate reason and you miss a dose, do not double up. Call the clinic and ask how to restart. Doubling a dose is one of the most common ways dogs get poisoned. ## Side Effects of Ivermectin in Dogs Most side effects at correct doses are mild, but serious reactions happen. The table below separates the two. | Side effect | How common or serious | What to do | |---|---|---| | Reduced tear production (dry eye) | Common in treated dogs. In one study of 128 dogs, tear values dropped significantly 36 hours after treatment, with an average drop of about 4.38 mm/min in treated dogs [6] | Ask your vet about a tear test if your dog is on repeated doses. Watch for red, dull, or squinting eyes | | Vomiting, drooling, loss of appetite | Uncommon at correct doses, usually mild | Call your vet if it lasts more than a day | | Dilated pupils, poor pupil response, vision changes | Serious. Seen in overdose cases [7] | Emergency visit | | Tremors, ataxia, incoordination | Serious. Seen in overdose cases [7] | Emergency visit | | Bradycardia (slow heart rate) | Serious. Seen in overdose cases [7] | Emergency visit | | Encephalopathy, seizures, coma | Rare but severe, reported in post-marketing surveillance [3] | Emergency visit immediately | The dry eye finding deserves attention because it can be easy to miss. In the study, tear production fell even at recommended doses, and the authors suggested that susceptible dogs could develop subclinical dry eye, which is why tear testing may be advisable [6]. If your dog is already on a medication that dries the eyes, or has a history of eye problems, tell your veterinarian. ## Who Should Not Take Ivermectin Some dogs should never receive ivermectin, or should receive it only with extreme caution. The biggest risk group is dogs with a mutation in the MDR1 gene, also called ABCB1. This mutation is most common in collies and related herding breeds, but it can appear in any dog. Dogs with this mutation cannot pump ivermectin out of the brain effectively, so normal doses can cause severe neurological signs [3][5]. Other dogs to flag for your veterinarian include: - Dogs already showing neurological signs, since it can be hard to tell drug toxicity from the underlying disease - Dogs with liver or kidney disease, because the drug may not clear normally - Very small dogs, since a small dosing error becomes a large overdose. The overdose case in the literature involved a 2.5 kg Shih Tzu [7] - Puppies and pregnant or nursing dogs, unless your veterinarian specifically recommends it - Dogs taking other drugs that affect P-glycoprotein, since these can raise ivermectin levels in the brain [5] Drug interactions matter. Any medication that interferes with the P-glycoprotein pump can increase the risk of neurotoxicity [5]. This includes some common veterinary drugs. Your veterinarian needs a full list of everything your dog takes, including supplements and flea and tick products. ## Overdose and When to Call for Help Ivermectin toxicity can progress quickly. In the reported overdose case, a dog developed ataxia, tremors, incoordination, absent pupil reflexes, bradycardia, and salivation within 12 hours of eating a 10 mg tablet [7]. Treatment with an intravenous lipid emulsion was started, neurological signs began improving about 2.5 hours later, and the dog recovered within 24 hours [7]. That outcome required intensive veterinary care. If you think your dog ate ivermectin, or ate a product containing it, do not wait for symptoms. Call your veterinarian or an animal poison control hotline right away. Have the product packaging, the estimated amount eaten, your dog's weight, and the time of ingestion ready. Signs that mean an emergency visit right now: - Tremors, twitching, or muscle rigidity - Wobbling, stumbling, or inability to stand - Dilated pupils or a blank stare - Drooling or vomiting - Slow heart rate or collapse - Seizure or unresponsiveness Do not try to induce vomiting at home unless a veterinarian tells you to. Do not give activated charcoal, milk, oil, or any home remedy. ## Limitations and When to Contact a Veterinarian The evidence for ivermectin as a cancer treatment in dogs is thin. There is no clinical trial showing it treats lymphoma. The only canine cancer trial involving it studied a different tumor type and produced inconsistent results across prior work [2]. Laboratory findings about anticancer effects have not been confirmed in dogs with cancer. There is also a real safety cost. Even at recommended doses, ivermectin reduced tear production in healthy dogs [6]. At higher doses or in susceptible dogs, it can cause severe neurological toxicity [3]. For a dog already fighting cancer, adding a drug with no proven benefit and known risks is a decision that needs careful thought. Individual cases need a veterinarian. Your oncologist knows your dog's diagnosis, stage, bloodwork, and current medications. That context matters more than any general article. Call your veterinarian the same day if your dog on ivermectin develops eye redness, squinting, reduced blinking, vomiting, or appetite loss. Go to an emergency clinic immediately for tremors, wobbling, dilated pupils, slow heart rate, or any change in consciousness. For routine questions about whether ivermectin fits into your dog's cancer plan, bring it up at your next scheduled visit, and ask specifically what evidence supports it for your dog's tumor type. If you are exploring supportive care, ask your oncologist about nutrition and monitoring. Two useful reads are [Cancer Diet for Dogs: Ketogenic Omega-3 and Antioxidant Protocol](/knowledge/veterinary-medicine/nutrition/cancer-diet-for-dogs-ketogenic-omega-3-and-antioxidant-protocol) and [Monitoring Immunotherapy in Veterinary Oncology: Response and Toxicity](/knowledge/veterinary-medicine/veterinary-pathology-microbiology/monitoring-immunotherapy-veterinary-oncology). ## Frequently Asked Questions ### Can ivermectin cure my dog's lymphoma? No. There is no clinical evidence that ivermectin cures or treats lymphoma in dogs. Lymphoma is treated with chemotherapy protocols that have been studied in dogs, and your oncologist can explain the expected remission rates and side effects for your dog's specific case. ### Is ivermectin safe for dogs at normal doses? It is generally well tolerated at approved doses for approved uses, but it is not risk-free. A study of healthy dogs found that tear production dropped significantly after treatment, and rare severe neurological reactions have been reported in real-world use. Your veterinarian can tell you whether your dog's breed, size, and medications raise the risk. ### Why do people say ivermectin fights cancer? Laboratory studies have shown that ivermectin can affect cancer cells in test tubes. Those results have not been confirmed in dogs with cancer. A finding in a dish does not mean the drug will shrink a tumor in a living animal without causing harm. ### Can I give my dog ivermectin from a farm supply store? No. Livestock ivermectin products are made for much larger animals and are easy to overdose. Some also contain other ingredients that are toxic to dogs. Only use ivermectin that your veterinarian has prescribed specifically for your dog. ### What should I do if my dog with cancer is already taking ivermectin? Tell your oncologist at your next visit, and sooner if you notice any side effects. Do not stop or change the dose on your own, especially if the drug was prescribed for heartworm prevention. Your veterinarian can review whether it should continue alongside cancer treatment. ## Related Articles - [Lymphoma in Dogs: CHOP Chemotherapy Protocol vs Prednisone Palliation](/knowledge/veterinary-medicine/dermatology-oncology/lymphoma-in-dogs-chop-chemotherapy-protocol-vs-prednisone-palliation) - [ivdd in dogs](/knowledge/veterinary-medicine/clinical-methods/ivdd-in-dogs) - [Canine Lymphoma: Diagnosis and Chemotherapy Protocols](/knowledge/veterinary-medicine/clinical-methods/canine-lymphoma-diagnosis-chemotherapy-protocols) - [Cancer Diet for Dogs: Ketogenic Omega-3 and Antioxidant Protocol](/knowledge/veterinary-medicine/nutrition/cancer-diet-for-dogs-ketogenic-omega-3-and-antioxidant-protocol) - [Monitoring Immunotherapy in Veterinary Oncology: Response and Toxicity](/knowledge/veterinary-medicine/veterinary-pathology-microbiology/monitoring-immunotherapy-veterinary-oncology) - [Cutaneous Lymphoma Dog: Comprehensive Veterinary Reference Guide](/knowledge/veterinary-medicine/oncology/cutaneous-lymphoma-dog) - [Prednisone for Dogs With Lymphoma and Other Cancers](/knowledge/veterinary-medicine/senior-and-chronic-care/prednisone-dogs-lymphoma-cancer) - [Milbemycin vs Ivermectin for Dogs: Which Is Safer?](/knowledge/veterinary-medicine/pet-medication-guide/milbemycin-vs-ivermectin-dogs) - [Ivermectin for Dogs With Mange: Does It Work?](/knowledge/veterinary-medicine/parasitic-diseases/ivermectin-dogs-mange) ## References 1. [Ivermectin in veterinary medicine: a narrative review of antiparasitic efficacy, resistance evolution, antiviral evidence, and One Health implications](https://pubmed.ncbi.nlm.nih.gov/42317461/). Frontiers in veterinary science, 2026. 2. [A clinical-cytological scoring system predicts response to vincristine with or without ivermectin in canine transmissible venereal tumor](https://pubmed.ncbi.nlm.nih.gov/41742510/). Journal of veterinary internal medicine, 2026. 3. [Ivermectin Toxicity in Humans and Animals: Clinical Spectrum, Mechanisms, and Management](https://pubmed.ncbi.nlm.nih.gov/41837342/). Journal of applied toxicology : JAT, 2026. 4. [Combination effect of Exportin 1 inhibitor (KPT-335) with doxorubicin or vincristine in canine lymphoma cell lines](https://pubmed.ncbi.nlm.nih.gov/41285475/). The Journal of veterinary medical science, 2026. 5. [Study of Pharmacokinetics for Ivermectin B1a from Beagle Dogs](https://pubmed.ncbi.nlm.nih.gov/38134186/). Journal of chromatographic science, 2025. 6. [Systemic Ivermectin Administration Reduces Aqueous Tear Production and Affects Ocular Surface Health in Clinically Healthy Dogs](https://pubmed.ncbi.nlm.nih.gov/41963771/). Veterinary ophthalmology, 2026. 7. [Intralipid emulsion therapy for ivermectin toxicity in a dog](https://pubmed.ncbi.nlm.nih.gov/40859605/). Veterinary medicine and science, 2025. ## Further Reading - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information)