Botulism in Dogs

By Catherine Barnette, DVM

What is botulism?

Botulism is a rare condition that causes paralysis in dogs. Botulism is caused by ingesting the botulinum toxin, which is a substance produced by the bacteria Clostridium botulinum.

Most cases of botulism in dogs are caused by eating dead animals or contaminated raw meat. Clostridium botulinum that grows in/on meat can release the botulinum toxin into its surroundings, allowing the toxin to be ingested by dogs who eat the contaminated meat.

When dogs eat contaminated meat, the toxin is absorbed by the intestines and enters the bloodstream. Botulinum toxin is then carried throughout the body, where it binds to nerve cells and causes paralysis.

"Botulinum toxin is then carried throughout the body, where it binds to nerve cells and causes paralysis"

botulism_dogsWhat are the signs of botulism?

Signs of botulism typically develop hours to days after ingesting contaminated meat, though the onset can be delayed up to six days. Clinical signs vary depending upon the amount of toxin ingested, although earlier onset of clinical signs is typically associated with more severe disease.

Botulism often affects the body in a characteristic way. The rear legs are often the first part of the body to be affected, and weakness in the rear legs is often the first sign of disease. Within 24 hours, this weakness progresses to include the front legs, as well as the muscles of the head and face.

"Affected dogs are mentally normal. They can sense pain and are aware of their environment."

Affected dogs are mentally normal. They can sense pain and are aware of their environment. Botulism's effects on muscle movement may lead to an inability to swallow, increased salivation, constipation, and eye inflammation (due to decreased tear production and an inability to blink).

In some cases, death may occur due to paralysis of the diaphragm. The diaphragm is the muscle that moves to inflate the lungs; when the diaphragm is paralyzed, a dog cannot breathe without the assistance of a mechanical ventilator. Fortunately, the diaphragm is better able to resist botulism paralysis than other muscles within the body, and therefore not all dogs require the use of a ventilator.


How is botulism diagnosed?

Diagnosing botulism can be difficult. Your veterinarian will start by doing a full examination of your dog and taking a thorough history to determine possible opportunities your dog may have had to ingest the botulinum toxin, along with the signs your dog has been showing and duration.

Routine laboratory tests, such as bloodwork and urinalysis, are typically normal in affected dogs, so diagnosis is usually based on history of exposure and observation of the dog. Blood, stool and/or vomit samples may be taken and tested for the botulinum toxin in the serum. X-rays may show evidence of pneumonia, paralysis of the respiratory muscles, or esophageal motility problems, all of which can be seen with this condition.


How is botulism treated?

If botulism exposure is known or suspected before the onset of clinical signs, the antitoxin can be administered. The antitoxin prevents the botulinum toxin from binding to nerve endings and causing clinical signs. Once signs of paralysis develop, the antitoxin is not effective.

Once signs have developed, treatment of botulism is focused on supportive care. This supportive care will require hospitalization; depending on the severity of your dog’s signs, he may require hospitalization at a facility with an intensive care unit.

The signs of botulism will typically resolve with time, and supportive care decreases the likelihood of complications. Affected dogs should be kept hospitalized on soft bedding, to prevent pressure sores. Mildly-affected dogs may need assistance with eating or drinking, while more severely affected dogs may require intravenous fluids to prevent dehydration and a stomach tube for feeding.

Many affected dogs lose the ability to empty their bladder, so the veterinary staff may need to manually express your dog’s bladder regularly or place a urinary catheter to keep the bladder empty. Your dog may require ointment to keep the eyes moist (if he is unable to blink), or antibiotics to treat secondary infections that may occur.

If your dog’s diaphragm becomes paralyzed, a mechanical ventilator may be used to allow him to breathe.

What is the prognosis for botulism?

Most affected animals recover within 14-24 days, if they receive appropriate supportive care. Without treatment, death due to paralysis of the diaphragm or secondary infection may occur.


How can botulism be prevented?

Botulism can be prevented by preventing your dog from eating raw meat or roadkill.

"Botulism can be prevented by preventing your dog from eating raw meat or roadkill."

There is no available vaccine against botulism.

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