Ivermectin dosage reference for cats (Heartgard)

Ivermectin (often known by brand names such as Heartgard, Ivomec, and Acarexx (otic)) is a macrocyclic lactone antiparasitic commonly used in veterinary medicine for Ear mite treatment (Otodectes cynotis), Heartworm prevention, Intestinal parasite treatment, Demodectic mange (off-label), and Notoedric mange (off-label). Understanding the correct dosage, administration, and potential side effects of Ivermectin is critical for your cat’s safety and well-being.

A typical Ivermectin dose for cats is around 0.2 mg/kg Single dose for ear mites (may repeat in 2 weeks); monthly for heartworm prevention, within a usual range of 0.024-0.4 mg/kg. Available forms include Injectable solution (used orally or by injection), Topical (otic), and Oral paste.

Ivermectin Dosage Calculator for Cats

Enter your cat’s weight below to estimate the Ivermectin dose from the 0.2 mg/kg guideline. Your veterinarian may adjust it for your cat’s age, condition, and other medications, so treat the result as an educational starting point, not a prescription.

Quick Dosage Chart

Typical Ivermectin amounts for common cat weights, for quick reference:

One Ivermectin Number Cannot Cover Every Use

This page’s record spans a wide 0.024–0.4 mg/kg range and uses 0.2 mg/kg as its standard arithmetic reference. That alone shows why weight is not enough: heartworm prevention, ear-mite treatment, and off-label parasite protocols do not share one interchangeable dose, route, or schedule.

The formulation must be selected before any volume can be calculated. Otic products, cat-specific preventives, injectable solutions, and concentrated horse or cattle products are not substitutes for one another. A small decimal or dilution error can be clinically important in a cat.

Use the calculator only to understand how the recorded 0.2 mg/kg value scales with weight. Do not use it to choose an indication, convert a large-animal product, or decide when to repeat treatment.

How to Give Ivermectin to Your Cat

Ivermectin administration in cats varies by indication, route, and formulation. Use only the exact cat-specific or compounded product supplied or identified by the prescribing veterinarian, and follow its label. Never convert, dilute, or measure a large-animal horse or cattle formulation at home; concentration errors can be dangerous in cats.

It is generally recommended to give Ivermectin with food to help reduce stomach upset. It may interact with Spinosad (increased ivermectin toxicity risk), Ketoconazole and other P-glycoprotein inhibitors (increased ivermectin levels), Other macrocyclic lactones (additive toxicity), and Benzodiazepines (may mask early neurotoxicity signs).

Side Effects and Safety

Common side effects include Transient lethargy, Decreased appetite, Drooling (if given orally and tastes the solution), and Mild diarrhea. More serious side effects can occur, such as Neurotoxicity (ataxia, tremors, blindness, seizures, coma), Hypersalivation and vomiting (early toxicity sign), Death (at toxic doses), and Severe allergic reaction.

When to Call the Vet

If your cat experiences any of the following, contact your veterinarian or an emergency clinic immediately:

• Wobbliness, tremors, or inability to walk (possible neurotoxicity)
• Dilated pupils or apparent blindness
• Seizures or loss of consciousness
• Excessive drooling or vomiting within hours of dosing
• Severe lethargy or unresponsiveness

Frequently Asked Questions