Toxic disorders of the peripheral nerves and neuromuscular junction in animals are caused by exposure to certain drugs, chemicals, or naturally occurring toxins that damage the nerves or neuromuscular junction.
Botulism
Botulism is intoxication with a neurotoxin produced by the bacterium Clostridium botulinum. It affects horses, cattle, sheep, and birds worldwide. It is uncommon in dogs and pigs. (For a complete discussion, see Botulism in Animals; for poultry in particular, see Botulism in Poultry.)
Ionophore Toxicosis
Ionophore toxicosis has been observed in horses, cattle, sheep, pigs, dogs, cats, and poultry; horses are particularly susceptible.
Food contaminated with the ionophore lasalocid has been reported to cause flaccid tetraparesis with hyporeflexia in dogs (1). In 1996, cat food contaminated with another ionophore, salinomycin, caused an outbreak of polyneuropathy in approximately 850 cats in the Netherlands and Switzerland. Affected cats had acute onset of tetraparesis, hyporeflexia, dysphagia, respiratory weakness, and eventual muscle atrophy. Histopathological findings in these cats consisted of degeneration of distal sensory and motor axons (2).
Animals with ionophore toxicosis usually recover with supportive care and removal of the offending food.
Organophosphate Toxicosis
Organophosphate toxicosis in animals is caused by exposure to an insecticide containing an organophosphate.
Clinical signs vary depending on the species affected, the specific chemical, and the dose and duration of exposure. See Organophosphate Toxicosis in Animals.
Tetanus
Tetanus is a neurological disease caused by the tetanus toxin (tetanospasmin), a neurotoxin produced by Clostridium tetani, a soil- and intestinal tract–associated bacterium. Infection typically occurs when the bacterium enters tissues through deep wounds. Tetanospasmin reaches the central nervous system via peripheral motor nerves, where it disrupts inhibitory neurotransmission and causes muscle rigidity and spasms. (For a more complete discussion, see Tetanus in Animals.)
Tick Paralysis
Tick paralysis, a rapidly progressive paralysis, is caused by neurotoxins produced by certain ticks. See Tick Paralysis in Animals.
Vincristine-Induced Neuropathy
The chemotherapeutic agent vincristine can cause a dose-dependent peripheral neuropathy in animals.
Clinical signs of vincristine-induced neuropathy are ataxia, tetraparesis, and weak spinal cord reflexes. Clinical signs improve or resolve slowly after discontinuation of vincristine.
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References
Segev G, Baneth G, Levitin B, Shlosberg A, Aroch I. Accidental poisoning of 17 dogs with lasalocid. Vet Rec. 2004;155(6):174-176. doi:10.1136/vr.155.6.174
Pakozdy A, Challande-Kathman I, Doherr M, et al A. Retrospective study of salinomycin toxicosis in 66 cats. Vet Med Int. 2010;2010:147142. doi:10.4061/2010/147142
