bits & pieces ASK THE VET Your horse health questions answered
Battling Botulism By Alfredo SAnchez-londoño, MV, MS, dAcVIM (lArge AnIMAl)
I recently read about a botulism outbreak which caused the deaths of 23 horses in Maine. Since there is no test for this, can you tell me what some of the symptoms and causes of botulism are, and what are the different forms of treatment?
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equine Journal
| July 2012
ally affect foals from a few days old to several months, with the majority of cases occurring between two and five weeks of age; affected foals usually lie down for longer periods of time than normal, and when forced to stand will have generalized muscle tremors. Forage poisoning most commonly occurs in adult horses that ingest the preformed toxin in forages that have been improperly dried and processed, such as round-baled hay, hay cubes, etc., or from feed contaminated with animal body parts that contain Cl. botulinum. Clinical signs of botulism can occur as early as 12 hours to as long as several days. The clinical signs in horses will be very similar, regardless of the route of toxicity. Common clinical signs identified include: difficulty swallowing, which will lead to the horse taking a longer time to eat its normal amount of food; poor or decreased muscle tone, resulting in reduced tongue tone, droopy eyelids, poor tail tone; decreased ability to retract the tongue after pulling it out of the mouth; generalized weakness; and muscle tremors that can lead to the horse lying down
Forage poisoning most commonly occurs in adult horses that ingest the preformed toxin within improperly dried and processed forages.
and having difficulty rising. In some cases, horses can present signs of colic, due to the lack of adequate intestinal motility and gas accumulation. The toxin can cause significant changes in the respiratory pattern and rate, which can lead to respiratory paralysis, and consequently, death. There are simple field tests that can be done to try to diagnose the disease in its early stages. As previously mentioned, the tongue tone is decreased, so gently pulling the tongue out and releasing it to determine how long it takes to go back into the mouth can give an early indication that there is a problem. A normal horse should retract the tongue very fast after pulling it out, but a horse with botulism may leave it out for a prolonged period of time. Another easy test to perform is the “grain test,” in which a small amount of feed is offered to the horse in a feed tub, and the horse is monitored to determine the time it takes to consume the feed offered. A normal
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Botulism is a disease that affects all warm-blooded animals and causes damage to the nerves and muscles, resulting in a lack of muscle tone with decreased ability to move, also known as flaccid paralysis. The clinical signs of the disease are a result of the neurotoxins produced by the bacteria clostridium botulinum. There are seven different neurotoxins (A, B, C, D, E, F and G) that have been identified, but the most common ones that affect horses are type B (85% of cases) and occasionally types A and C. The botulism toxin is considered the most poisonous naturally-occurring substance in the world, so it takes a very small amount of toxin to cause death in an adult horse. The bacteria can live in the soil in most areas of the United States, but is very commonly found in the Northeast, Ohio Valley, and along the eastern seaboard. The disease can occur by one of three routes: ingestion of the toxin in forage (most commonly in adult horses and cattle), ingestion of spores (affects mostly foals with a syndrome known as Shaker Foal), and through wounds contaminated with botulism spores with production and absorption of neurotoxins. Horses are more susceptible to botulism than cattle. Wound botulism most commonly occurs in horses after castrations, umbilical hernia repairs, or deep puncture wounds that occur with injections of irritating substances. The disease can be severe and will cause respiratory complications, that if untreated or not recognized early on, can lead to death. Shaker Foal Syndrome can occasion-