Merck Manual

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Pet Owner Version

Botulism in Dogs


Henry R. Stämpfli

, DMV, Dr Med Vet, DACVIM-LAIM, Department of Clinical Studies, Ontario Veterinary College, University of Guelph

Reviewed/Revised Jun 2018 | Modified Oct 2022

Botulism is a motor paralysis caused by eating food containing the toxin (a poisonous substance) produced by Clostridium botulinum bacteria. This bacterium grows rapidly in decomposing animal tissue and sometimes in plant material. It results in rapid death due to the paralysis of vital organs. Botulism is an intoxication, not an infection.

There are 7 types of Clostridium botulinum; the C1 type is most common in animals. The usual source of the toxin is decaying carcasses or spoiled vegetation. Botulism is most common in wild water birds (for example, ducks) and occurs only sporadically in dogs.

The signs of botulism are caused by muscle paralysis and include progressive motor paralysis, disturbed vision, difficulty chewing and swallowing, and progressive weakness. Death is usually due to paralysis of the lungs or heart. Treatment is usually not possible, although a few experimental therapies have had limited success.

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