Tick paralysis in horses

J Vet Intern Med. 2019 Jun 3. doi: 10.1111/jvim.15540.
Presumptive tick paralysis in 2 American Miniature horses in the United States.
Trumpp KM1, Parsley AL1, Lewis MJ1, Camp JW Jr2, Taylor SD1.

Author information:
1. Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, Indiana.
2. Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, West Lafayette, Indiana.
Abstract
RATIONALE:

Tick paralysis has not been reported in horses in North America.
CLINICAL FINDINGS:

Two American Miniature horses were examined for progressive weakness and recumbency. Numerous ticks (Dermacentor variabilis) were found on both horses. Horse 1 was recumbent (grade 5/5 gait deficit) on presentation, whereas Horse 2 was standing but ataxic (grade 4/5 gait deficit) and tetraparetic. Both horses had decreased tongue and tail muscle tone, and had normal spinal reflexes. Cerebrospinal fluid cytology was normal. Equine herpesvirus-1 testing was negative.
PERTINENT INTERVENTIONS:

Ticks were removed within 24 hours of presentation. Both horses were treated topically with permethrin. Supportive care included fluid therapy, treatment for corneal ulceration, and frequent repositioning during recumbency.
OUTCOME:

Within 48 hours of tick removal, both horses were neurologically normal.
CLINICAL RELEVANCE:

Ours is the first reported case of presumptive tick paralysis in horses in North America. Although rare, tick paralysis should be considered in horses presented with acute-onset weakness progressing to recumbency.

© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.