Is ivermectin safe for dogs?

  • Ivermectin is a medicine veterinarians use for heartworm prevention in dogs, including other parasites found in the bodies of small animals(1).
  • A veterinarian can also prescribe the drug to treat capillaria, and mites in dogs, and it is also considered an ‘off-label’ medicine(2).
  • Certain dogs that have the MDR1 gene, a mutation that makes them incompatible with ivermectin use, are at risk of life-threatening toxicity when taking the medication(3).
  • Natural alternatives to ivermectin for dogs such as black walnut extract(4) and CBD oil(5) are considered a safer choice by holistic veterinarians in treating parasites in canines.
  • To avoid complications, pet owners planning to use natural alternatives to ivermectin for dogs should always consult with a veterinarian first.

What is Ivermectin?

Ivermectin is an anti-parasitic agent that doctors commonly administer to dogs and small animals as a heartworm preventive, and as a treatment to certain types of parasites in their bodies(6).

The drug may be prescribed as an injectable or oral treatment for mites, capillaria, and certain skin conditions (demodicosis or demodectic or sarcoptic mange) in dogs. It is classified as ‘off-label’ or ‘extra-label’ which is a common practice in veterinary medicine. (7)

A clinical study in 1997 proved the efficacy of ivermectin when it was used in the successful application and treatment of scabies (sarcoptic mange) on ninety dogs(8).

Ivomec and Heartgard are popular brands of ivermectin for dogs.

Ivermectin Dosage for Dogs Information

Veterinarians approve the use of ivermectin on dogs when it comes to preventing dirofilariasis or the parasitic infestation of microfilariae nematodes. Oral doses of ivermectin are typically 0.006 and 0.024 mg/kg, respectively, once every month(9).

The dosage regimens for dogs vary and will depend on the species and parasites to be treated. Prevention of heartworm disease requires the lowest dose, while other parasites will need higher doses(10).

Dogs that require high doses, but have not previously received ivermectin, begin with a low dose of 50 to 100 mcg/kg which are increased by increments of 50 to 100 mcg/kg/day on following treatments daily. During this time, doctors observe a dog for signs of central nervous system toxicity such as tremors, sedation, and ataxia(11).

The majority of dogs can tolerate oral intake of ivermectin to a maximum dose of 2.5 mg/kg of body weight before clinical signs of toxicity start to show up. However, dogs younger than six weeks old or those that do not have a current negative heartworm preventative test should not take this medication(12).

Side Effects of Ivermectin on Dogs

Ivermectin is generally safe for use in most dogs and is an effective way to treat and prevent several forms of parasitic infections. However, dogs that have the MDR1 mutation gene, a mutation that causes life-threatening reactions to dogs that consume ivermectin, are at risk of toxicosis(13).

Dogs that have this gene mutation are also susceptible to other medications, including acepromazine, loperamide, and other chemotherapy drugs(14).

The American Kennel Club lists the following dog breeds as being possibly sensitive to ivermectin:

  • Australian Shepherd
  • Border Collie
  • Collie
  • English Sheepdog
  • English Shepherds
  • German Shepherd
  • Longhaired Whippet
  • Miniature American Shepherd
  • Old English Sheepdog
  • Shetland Sheepdog (Shelties)
  • Silken Windhound
  • Skye Terrier
  • Working Collie
  • Mixed herding breeds

Take note that not all individual dogs in the breeds listed above have the mutation(15).

Pet owners should not use ivermectin together with other spinosad (Trifexis or Comfortis) since this can increase the potential of ivermectin’s adverse reactions(16).

Ivermectin Overdose Effects in Dogs

The overdose of ivermectin in a dog happens when there is a high enough concentration in their body. Here are the following symptoms of ivermectin overdose in dogs:

  • Vomiting
  • Mental dullness
  • Unsteadiness when walking
  • Dilated pupils
  • Drooling
  • Blindness
  • Seizures
  • Tremors
  • Coma

If ivermectin toxicity in dogs is identified early on, decontamination in the form of washing or inducing vomit can help. A veterinarian may also recommend intravenous fluid therapy, mechanical ventilation, endotracheal intubation, extensive nursing care, seizure control, and nutritional support(17).

Natural Alternatives To Ivermectin For Dogs

A study in 2013 looked into the possibility of natural products being used as a source to treat diseases caused by parasites. One reason for the study was due to the growing resistance of parasitic infestations to anti-parasitic drugs such as ivermectin(18).

As an alternative to the active ingredients used in these medications, doctors began looking into herbal plants as another option(19).

Black Walnut

Dr. Carolyn Blakey DVM, a holistic veterinarian of Westside Animal Clinic in Richmond, Indiana, follows a multi-pronged approach for her heartworm preventive measures in dogs. One of her treatments includes the use of black walnut, which she claims is spot-on in weakening the adult roundworms(20).

“The herbal treatment’s effect on the worms, and subsequent improvement in their host, is astonishing,” says Blakey. “It’s incredible. The dogs start feeling better within days because their circulation is improved, and their heart can function better.”(21)

Black walnut is commonly available in most health food stores. Blakey suggests that dog owners consult with a holistic veterinarian first before they plan to take on this kind of treatment.


In 2019, a study showed that cannabidiol (CBD) is an effective inhibitor of the intestinal parasite called Giardia intestinalis(22). Giardia, a parasite that affects both humans and dogs, can cause symptoms such as abdominal discomfort, nausea, gas, diarrhea, and vomiting.

Human beings have been consuming CBD oil for its therapeutic properties. Since humans and most animals share the same endocannabinoid system (ECS)(23), the part of the body that regulates cannabinoids, we can conclude that dogs can also benefit in taking products with cannabidiol as an active ingredient.  

Just like black walnut extract, CBD may offer a much safer alternative to ivermectin since the medicine can be harmful to dogs that have high ivermectin sensitivity. Pet owners can administer CBD in several ways, such as giving it orally, massaging on affected areas, or including in their diet.

There is still no dosing chart available for dogs at this time since CBD is not yet approved by the U.S. Food and Drug Administration (FDA).

Small animal owners must consult first with a veterinarian before deciding to implement CBD as a treatment for their pets.


Ivermectin is an effective medication in treating heartworm infection, ear mites, and other parasites in small and large animals. However, certain canines can possess a specific genetic mutation in their genes, which can cause adverse effects with ivermectin intake.

Holistic veterinarians suggest the use of natural alternatives to ivermectin that are more compatible with dogs while not causing harmful changes to their wellbeing.

CBD oil and black walnut extract may provide healing properties that pet owners can use as a substitute to the said drug.   

As with any pet regimen, owners should talk to their veterinarian first before administering these products to their canines.

  1. Coates, Jennifer DVM (2013, January 8). The Safe Use of Ivermectin. Retrieved from:
  2. Gollakner, Rania BS DVM (2019). Ivermectin. Retrieved from:
  3. Paddock, Arliss (2015, December 4). Common Heartworm Medication Ivermectin Can Have Serious Side Effects for Some Breeds. Retrieved from:
  4. Kerns, Nancy (2001, April 24). Treating Heartworm Holistically. Retrieved from:
  5. Gavinho B., Rossi I. V., Evans-Osses I., Lange S., Ramirez M. I. (2019). Peptidylarginine deiminase inhibition abolishes the production of large extracellular vesicles from Giardia intestinalis, affecting host-pathogen interactions by hindering adhesion to host cells. Biorxiv 586438. 10.1101/586438
  6. Coates, Jennifer DVM (2013, January 8). op. cit.
  7. Gollakner, Rania BS DVM (2019). op. cit.
  8. M Paradis, C de Jaham, and N Pagé. Topical (pour-on) ivermectin in the treatment of canine scabies. Can Vet J. 1997 Jun; 38(6): 379–382.
  9. Mealey, Katrina DVM, PhD, DACVIM, DACVCP (2013). Small Animal Toxicology (Third Edition). Retrieved from:
  10. Papich, Mark DVM, MS, DACVCP (2016). Saunders Handbook of Veterinary Drugs (Fourth Edition). Retrieved from:
  11. Ibid.
  12. Gollakner, Rania BS DVM (2019). op. cit.
  13. Paddock, Arliss (2015, December 4). op. cit.
  14. Ibid.
  15. Ibid.
  16. Brooks, Wendy DVM, DABVP (2001, January 1). Ivermectin (Ivomec, Heartgard 30, Acarexx, Iverheart Plus). Retrieved from:
  17. Coates, Jennifer DVM (2013, January 8). op. cit.
  18. D. Ndjonka, L. Nakamura Rapado, A. M. Silber, E. Liebau, and C. Wrenger. Natural Products as a Source for Treating Neglected Parasitic Diseases. Int J Mol Sci. 2013 Feb; 14(2): 3395–3439. Published online 2013 Feb 6. doi: 10.3390/ijms14023395.
  19. A.C.F.L., Reis I.F., Bevilaqua C.M.L., Vieira L.S., Echevarria F.M., Melo L.M. Anthelmintic resistant nematodes in sheep and goat herds in the state of Ceará, Brazil. Ciencia Rural. 2003;33:339–344
  20. Kerns, Nancy (2001, April 24). op. cit.
  21. Ibid.
  22. Gavinho B., Rossi I. V., Evans-Osses I., Lange S., Ramirez M. I. (2019). op. cit.
  23. R. Silver. The Endocannabinoid System of Animals. Animals (Basel). 2019 Sep; 9(9): 686. Published online 2019 Sep 16. doi: 10.3390/ani9090686.
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