Ivermectin

Broad-spectrum antiparasitic for internal and external parasites in horses (strongyles, ascarids, bots, pinworms, mites, lice), cattle, and dogs. Macrocyclic lactone antiparasitic (avermectin class). Mechanism: potentiates GABA-gated chloride channels (GluCl channels) in invertebrate nerve and muscle cells → hyperpolarization → paralysis of susceptible parasites. High selectivity for invertebrate receptors over vertebrate GABA-A receptors. Broad spectrum: strongyles, ascarids, bots, pinworms, mites, lice. Do not use in Collie breeds (MDR1/ABCB1 mutation). Key information Do NOT use in MDR1/ABCB1 mutation dogs (many herding breeds — collies, Australian shepherds, etc.). Avoid in foals under 4 months. Injectable: for cattle/swine only. Horses: oral paste or liquid only. Cattle: USDA withdrawal times apply. Toxicity signs: mydriasis, ataxia, tremors.

Oral paste (horses): administer via dose syringe into the back of the mouth at the correct weight marking on the plunger. Twist plunger lock before use. Oral (dogs/cats — heartworm prevention): Administer orally. May be given with food to improve compliance and reduce GI upset. Administer with food to reduce GI adverse effects. Injectable (cattle): administer SQ in the neck area. Pour-on (cattle): apply along the backline. Store at room temperature; protect from light. If a dose is missed Administer as soon as you remember. If it is almost time for the next scheduled dose, skip the missed dose and resume the normal schedule. Never double up doses to make up for a missed one. Monthly preventatives: give when remembered, then resume normal monthly schedule.

CNS toxicity in susceptible breeds (Collie, Australian Shepherd, Shetland Sheepdog, Border Collie, MDR1/ABCB1 mutant dogs): ataxia, tremors, hypersalivation, blindness, coma, death. GI: vomiting, diarrhea, anorexia (mild at labeled doses). Foals and young horses: generally safe at labeled doses. Do not use in horses destined for human consumption. Soft tissue injection reactions (SQ use — irritation).

For animals Collies, Australian Shepherds, Shetland Sheepdogs, Border Collies, and MDR1/ABCB1-mutant dogs: CONTRAINDICATED at antiparasitic doses — severe CNS toxicity (coma, death). Test for MDR1 mutation before use in at-risk breeds. Do not use in horses intended for human consumption. Use with caution in pregnant animals. Foals: safe at labeled doses. For people handling this medication Wash hands thoroughly with soap and water after handling. Avoid contact with eyes; if contact occurs, flush with water for 15 minutes and seek medical attention. Keep out of reach of children. If accidental ingestion occurs, contact Poison Control (1-800-222-1222). Macrocyclic lactone — Wash hands thoroughly with soap and water after handling. after handling. Generally safe at labeled doses. Avoid ingestion. Keep out of reach of children. Do not use human head lice ivermectin products in pets without veterinary guidance.

Contact your veterinarian immediately. Signs of ivermectin toxicity include severe neurological signs: fixed dilated pupils, ataxia, tremors, seizures, blindness, and coma. MDR1/ABCB1 mutation dogs are especially sensitive. Emergency supportive care including IV lipid emulsion therapy is required. Contact your veterinarian, a veterinary emergency clinic, or the ASPCA Animal Poison Control Center (888-426-4435) immediately. Do not induce vomiting unless specifically directed by a veterinary professional.