Ivermectin dosage for a small / toy breed
under 22 lb (10 kg)
The short answer
For a dog weighing under 22 lb (10 kg), the dose of Ivermectin reported in the literature is 0.3-0.6 mg/kg per day, given daily, or five days on / two days off, over 4-12+ weeks. It is studied in this weight class primarily for investigational oncology adjunct — mdr1 testing required first. These figures are reported as published and are not recommendations — the dose for an individual dog must be set by a veterinarian who has examined the animal.
Worked examples at specific weights
Calculated from the reported range of 0.3–0.6 mg per kg of body weight.
| Body weight | Calculated dose range | Frequency |
|---|---|---|
| 2 kg (4 lb) | 0.6–1.2 mg | Daily, or five days on / two days off |
| 5 kg (11 lb) | 1.5–3 mg | Daily, or five days on / two days off |
| 8 kg (18 lb) | 2.4–4.8 mg | Daily, or five days on / two days off |
For an exact figure at your dog's weight, use the dose calculator.
Typical breeds in this weight class
Chihuahua, Yorkshire Terrier, Dachshund, Pomeranian, Shih Tzu and similarly sized dogs generally fall within under 22 lb (10 kg). Weigh your dog rather than estimating — dosing is calculated per kilogram and an estimate that is out by a few kilos changes the figure materially, particularly at the smaller end.
Breed-specific risk in this weight class
Shetland Sheepdog — MDR1 (ABCB1) mutation risk — genetic testing required before ivermectin
This breed carries a meaningful frequency of the MDR1 gene mutation, which prevents the drug-efflux protein at the blood-brain barrier from clearing ivermectin out of the central nervous system. Affected dogs develop neurotoxicity at doses other dogs tolerate without difficulty, and at the investigational oncology doses discussed on this site that reaction can be fatal. A cheek-swab test through Washington State University or a commercial laboratory settles the question and must be done before the first dose.
Before dosing at all
⚠ MDR1 gene mutation — testing is mandatory
Dogs carrying the MDR1 (ABCB1) mutation cannot clear ivermectin from the brain and suffer neurotoxicity at doses other dogs tolerate. At the investigational oncology doses discussed here, that reaction can be fatal. Affected breeds include Collies, Australian Shepherds, Shetland Sheepdogs, Old English Sheepdogs, Border Collies, Long-haired Whippets, and any mixed breed with herding ancestry. The test is a simple cheek swab available through Washington State University and commercial laboratories. It must be done before the first dose.
Common questions
How much Ivermectin for a small / toy breed?+
For a dog in the under 22 lb (10 kg) range, the reported dose is 0.3-0.6 mg/kg per day, given daily, or five days on / two days off, typically for 4-12+ weeks. At a representative weight of 5 kg (about 11 lb), that works out to roughly 1.5–3 mg per dose. These figures are reported from the source literature and are not recommendations.
How often should a small / toy breed be given Ivermectin?+
Daily, or five days on / two days off is the reported frequency, over a course of 4-12+ weeks. See the cycling guide for how breaks are structured.
Is Ivermectin safe for a small / toy breed?+
Ivermectin's safety in dogs splits cleanly along one genetic line. In dogs without the MDR1 mutation it has decades of use as a heartworm preventive and is generally well tolerated. In dogs carrying the MDR1 (ABCB1) mutation it cannot be cleared from the brain, and at the investigational oncology doses discussed here the resulting neurotoxicity can be fatal. Collies, Australian Shepherds, Shelties, Old English Sheepdogs, Border Collies and herding mixes are the high-risk populations. The cheek-swab test is inexpensive and must precede the first dose.
References
- 1.CANINE STUDYZhu M, et al. Ivermectin-induced apoptosis of canine mammary tumor cells through regulation of the cell cycle and WNT signaling. BMC Veterinary Research, 2019. PMC6679554
- 2.Juarez M, Schcolnik-Cabrera A, Duenas-Gonzalez A The multitargeted drug ivermectin: from an antiparasitic agent to a repositioned cancer drug. American Journal of Cancer Research, 2018. PMID 29344093
- 3.Tang M, et al. Ivermectin, a potential anticancer drug derived from an antiparasitic drug. Pharmacological Research, 2021. PMC7505114
- 4.Dominguez-Gomez G, et al. Ivermectin as an inhibitor of cancer stem-like cells: antitumor effects at clinically feasible concentrations. Cancer Chemotherapy and Pharmacology, 2020. View source
Other weight classes: Ivermectin for a medium breed, Ivermectin for a large / giant breed.
Educational information — not veterinary medical advice
Everything on this page is compiled from published peer-reviewed literature for educational and research purposes. It does not establish a veterinarian-client-patient relationship (VCPR) and is not a substitute for veterinary examination and diagnosis. Most compounds described here are investigational or used off-label and are not FDA-approved for these purposes in dogs. Extralabel drug use in animals requires a valid VCPR and the direct supervision of a licensed veterinarian under AMDUCA (21 U.S.C. §360b). Dosing figures are reported as they appear in the source literature and are not recommendations.