Amitraz
Amitraz is a formamidine acaricide and insecticide used primarily in veterinary medicine for the treatment of generalized demodicosis in dogs, as well as for flea and tick control. * **Clinical Pearl:** Amitraz is highly effective against *Demodex* mites but requires strict adherence to safety protocols due to its potent alpha-2 adrenergic agonist effects in mammals. * It is available as a liquid concentrate for dilution (e.g., Mitaban) and in impregnated collars (e.g., Preventic). * **Toxicity Warning:** It is highly toxic to cats, rabbits, and horses. Use in these species is generally avoided or done strictly extra-label with extreme caution.
Mechanism: Acts as a **monoamine oxidase (MAO) inhibitor** in susceptible mites โ alters neurotransmitter breakdown โ CNS toxicity and death. Additionally, acts as an **alpha-2 adrenergic agonist** in mammals โ inhibits insulin release โ transient hyperglycemia and sedation. Also inhibits **prostaglandin synthesis**.
Dosing by species
- Generalized demodicosis (Labeled Protocol) ยท 250 ppm (one 10.6 mL bottle in 2 gallons of warm water) ยท topical ยท q14d ยท 3-6 treatments (or until 30 days past two negative skin scrapings) ยท Apply to entire animal and air dry. DO NOT rinse or towel dry.
- Generalized demodicosis (Extra-label Protocol 1) ยท 250 ppm, 500 ppm, or 1000 ppm ยท topical ยท q7d ยท Until 30 days past two negative skin scrapings ยท Step up concentration if lower doses fail. Increased risk of toxicity at higher doses.
- Generalized demodicosis (Extra-label Protocol 2) ยท 0.125% solution (1 mL of 12.5% Taktic in 100 mL water) ยท topical ยท q24h ยท Until 30 days past two negative skin scrapings ยท Rub onto one-half of the dog's body and alternate sides daily.
- Otic demodicosis ยท 1 mL of 12.5% Taktic in 8.5 mL mineral oil ยท topical ยท q3-7d ยท Until resolved ยท Discontinue if irritation develops.
- Generalized mite infestations (canine demodicosis, sarcoptic acariasis and cheyletiellosis) ยท Diluted as a dip, left on the coat ยท topical ยท As directed (typically weekly or bi-weekly depending on specific product label) ยท Until clinical and microscopic resolution ยท Clipping long-haired coats will improve penetration. Animals should not be bathed or allowed to swim for 48 hours after application.
- Follicular demodicosis (Demodex cati) ยท 0.0125% (125 ppm) ยท topical ยท q7-14d ยท Until resolved ยท Extra-label. Monitor very closely for side effects. Use E-collar until dry.
- Surface demodicosis (Demodex gatoi) ยท 0.0125% (125 ppm) ยท topical ยท q7d ยท 12 weeks ยท Extra-label. Monitor very closely for side effects. Use E-collar until dry.
Routes of administration
Contraindications
- Cats and rabbits (highly toxic, though extra-label protocols exist)
- Chihuahuas and toy breeds (use with extreme caution)
- Puppies less than 4 months of age
- Dogs with deep pyodermas and draining tracts (treat infection first)
- Brittle diabetic patients
- Pregnant or nursing animals
Adverse effects
- Transient sedation (up to 72 hours)
- Ataxia
- Bradycardia
- Vomiting and diarrhea
- Hypothermia
- Transient hyperglycemia
- Pruritus, erythema, and edema at application site
- Seizures (rare)
Drug interactions
- Corticosteroids ยท Immunosuppression can worsen demodicosis; concomitant use is contraindicated.
- Selegiline ยท Concurrent use of MAO inhibitors increases risk of toxicity.
- Amitriptyline ยท Concurrent use with tricyclic antidepressants is not recommended.
- Clomipramine ยท Concurrent use with tricyclic antidepressants is not recommended.
- Alpha-2 agonist sedatives (e.g., dexmedetomidine, xylazine) ยท Additive or synergistic CNS depression and cardiovascular effects (bradycardia). ยท major
- Other ectoparasiticides ยท Potential for increased toxicity. ยท moderate
Monitoring
- Resolution of clinical signs (negative skin scrapings)
- Blood glucose levels (especially in diabetic patients)
- Heart rate and body temperature
- Signs of excessive sedation or CNS depression
Overdose
Toxicity can be significant, especially if amitraz-containing collars are ingested. * **Signs:** Ataxia, severe CNS depression, bradycardia, hypothermia, and marked hyperglycemia. * **Treatment:** Emesis (if asymptomatic), endoscopic retrieval of ingested collars, activated charcoal, and cathartics. * **Antidotes:** **Yohimbine** (0.11-0.2 mg/kg IV) or **Atipamezole** can effectively reverse the alpha-2 adrenergic mediated signs (sedation, bradycardia, hyperglycemia). Repeated doses may be necessary due to the short half-life of the reversal agents.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.