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Amitraz toxicity
Synonym(s): Insecticide, flea collar toxicity
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.
Presenting signs
- Depression.
- Ataxia.
- Weakness.
- Tremors.
- Vomiting.
Acute presentation
- Acute onset of neurologic and gastrointestinal signs, generally within 2-6 hours of exposure.
Age predisposition
- Older animals may be predisposed.
Breed/Species predisposition
- Toy breed dogs may be more susceptible, especially to the topical product.
Public health considerations
- Without proper precautions, humans can be exposed to toxic levels of amitraz when administering the topical product.
Cost considerations
- Cost will depend on the severity of the clinical signs and the response to therapy. Many dogs will respond quickly.
- Dogs presented moribund may require extensive therapy.
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
General- 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
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
Other sources of information
- Gwaltney-Brant S (2004) Insecticides and Molluscicides.I n:Clinical Veterinary Toxicology.(ed) Plumlee KH. Mosby. St. Louis, pp177-178.
- Gfeller R W & Messonnier S P (1998) Handbook of Small Animal Toxicology & Poisonings. Mosby. St. Louis. pp 77-79.
- Osweiler G D (1996) Toxicology. Lippincott Williams & Wilkins. Philadelphia. pp 245-246.
Organisation(s)
- ASPCA Animal Poison Control Center: www.aspca.org/pet-care/animal-poison-control, telephone (888) 426-4435.
- Veterinary Poisons Information Service (VPIS); www.vpisglobal.com, telephone + 44 (0) 2073 055 055.