Introduction

• Amitraz Amitraz is a formamidine acaricide available as a topical preparation (dips, shampoos, lotions, sprays) for demodicosis Skin: demodectic mange and impregnated in a neck collar for tick control in dogs.
• Amitraz toxicity occurs when the topical formulation is improperly mixed or applied or the dog ingests the tick collar.
• Many products with amitraz also contain xylene. Some of the clinical signs associated with amitraz toxicity may be due to xylene toxicity.
• Amitraz is not approved for use in cats.

Pathogenesis

Etiology

• Amitraz toxicity occurs after ingestion of amitraz impregnated tick collars or following topical administration of amitraz for demodicosis, or accidental oral exposure to topical products.

Predisposing factors

• Sick, elderly or debilitated animals may be more predisposed and may take longer to recover.

Pathophysiology

• Amitraz is an a adrenergic agonist that has primary activity in the central nervous system resulting in sedation. It also is thought to have some peripheral alpha-1 and alpha-2 adrenergic activity. Amitraz is also thought to be a weak monoamine oxidase inhibitor.
• The bradycardia associated with amitraz toxicosis is due to an alteration of autonomic function, not a direct effect of the amitraz. Death is thought to occur to due profound bradycardia and hypotension.
• Stimulation of the postsynaptic alpha-2 receptors leads to mydriasis.
• Smooth muscle contractility is inhibited, leading to decreased intestinal motility.
• Insulin release is suppressed resulting in hyperglycemia.
• LD50 is 100 mg/kg for dogs.
• Acute oral exposure dose of 20 mg/kg in dogs has been associated with clinical signs of illness; acute oral exposure dose of 4.0 mg/kg in dogs has been associated with hypothermia.

Timecourse

• Signs of toxicity generally develop within 2 to 6 hours of exposure or ingestion. The half-life of amitraz is about 24 hours.

Diagnosis

Treatment

Prevention

Outcomes