Botulism in Dogs: What It Is and When To Seek Veterinary Care

Botulism in dogs is a rare but potentially fatal illness caused by a toxin produced by the bacteria Clostridium botulinum. Dogs are typically exposed by eating decomposing animal carcasses or spoiled vegetation, and the toxin can cause rapidly progressing muscle weakness and paralysis.  

Botulism is a medical emergency because paralysis can eventually affect the muscles a dog needs to breathe. If your dog develops sudden or worsening weakness, especially after possible exposure to a dead animal or rotting material, contact a veterinarian immediately.   

With prompt, intensive supportive care, many dogs can make a full recovery. 

What Is Botulism in Dogs?

Botulism in dogs is a rare but potentially fatal illness caused by a toxin produced by the bacteria Clostridium botulinum. 

Dogs become affected by eating decomposing animal carcasses or spoiled vegetation where the bacterium grows. 

Once eaten and absorbed from the stomach and intestines, the toxin attacks a dog’s nerves, resulting in weakness (paresis) and eventual paralysis. If untreated, this can progress quickly to breathing difficulties or death. 

Botulism in dogs is considered a medical emergency. If you believe your pet is experiencing any of the signs of botulism, contact your local veterinarian immediately. 

Symptoms of Botulism in Dogs

Signs of botulism in dogs may develop within a few hours but can be delayed up to six days. Symptoms can vary based on the amount of toxin consumed, but the earlier the signs appear, the more serious the disease. 

Clinical signs of botulism in dogs include: 

• Vomiting/diarrhea    
• Progressive, symmetrical, ascending weakness that begins in the rear limbs. This is a classic hallmark sign of botulism in dogs. It means weakness that began in the back legs has moved up the body to the front legs, and then to the head and neck. As this occurs, you may see these additional symptoms: 
  • Inability to walk 
  • Inability to hold up the neck and head 
  • Facial paralysis including decreased jaw tone, decreased ability to chew or swallow, and drooling or hypersalivation 
  • Urinary retention (inability to pee) and constipation (unable to poop) 
  • Difficulty breathing 
  • Paralysis of all four limbs (quadriplegia) 

Despite being paralyzed, affected dogs are mentally normal, and can still sense their environment and feel pain. 

If left untreated, most pets die of botulism due to respiratory distress as the muscles used for breathing, such as the diaphragm, become paralyzed and the dog is unable to breathe.  

The paralysis can also affect other organs that contain muscle, such as the heart, and this can also be fatal. 

If your pet is experiencing any of the above clinical signs of botulism in dogs, bring them to an emergency veterinarian immediately.   

Causes of Botulism in Dogs

Botulism in dogs is caused by the botulinum toxin produced by the bacteria C. botulinum. 

There are seven subtypes of C. botulinum (A, B, C, D, E, F, and G), and all of them have the same effect on the nervous system.  

Subtypes A, B, E, and F are associated with botulism in humans, while most cases in dogs are caused by subtype C. 

Dogs become infected with botulism after eating food or other material containing the botulinum toxin. Common sources include: 

• Dead animals or carcasses: an important source for dogs that spend lots of time outside and those that roam, hunt, or scavenge for their meals. Eating dead birds, rodents, rabbits, fish, livestock, or other decomposing animals is a risk because after an animal dies, its tissues contain little oxygen and are a prime environment for botulism spores to grow. 
• Spoiled meat or improperly stored food also provides a low-oxygen environment. This can become a concern for dogs that eat homemade meals that are not properly cooked or refrigerated.  
• Garbage or compost 
• Contaminated raw food 
• Decaying organic material  

Once a dog consumes the toxin, it’s absorbed in the stomach and intestines and carried in the bloodstream to the nerves.  

Nerves in the body are used to signal muscles to contract. Botulinum toxin blocks this process so that the muscles are unable to contract, creating muscle weakness and paralysis. 

The diaphragm muscle separates the abdomen and thorax. Its contraction plays a major role in breathing. Luckily, it is more resistant than other muscles in the body to the botulinum toxin, but once affected, a dog cannot breathe and without therapy they will die. 

Botulism is not contagious between dogs through touching, licking, coughing, or sharing water. However, if two dogs share the same environment or contaminated food source, they may contract the disease at the same time but not from each other.  

How Veterinarians Diagnose Botulism in Dogs

Veterinarians diagnose botulism in dogs based on medical history, symptoms, and by ruling out other causes of paralysis, since there is no quick and reliable test currently available.  

Botulism can be difficult to diagnose because it is very rare and its symptoms closely resemble other conditions, including: 

• Tick paralysis 
• Intervertebral disc disease (IVDD) 
• Degenerative myelopathy 
• Toxin exposure 
• Myasthenia gravis 
• Other nerve and muscle diseases  

If you suspect your dog has botulism, it’s very important to share any history of possible exposure to animal carcasses, rotting vegetation, or raw meat with your veterinarian to help them reach a diagnosis. 

Current tests to diagnose botulism involve highly specialized laboratory testing to detect the botulinum toxin in blood, feces, vomit, or the ingested material.  

Your veterinarian will start with a thorough physical examination to assess weakness, spinal reflexes, pain, and fever. They will also perform a complete orthopedic and neurologic examination. 

To further evaluate your dog and help rule out other causes of paralysis, your veterinarian may also recommend: 

• Blood work, including complete blood count (CBC) and serum blood chemistry 
• Urinalysis 
• X-rays to assess for signs of pneumonia or changes in the esophagus (megaesophagus)

Treatment of Botulism in Dogs

While there is an antitoxin for botulism, it’s not readily available in veterinary hospitals and must be given before the toxin reaches the nerve endings and causes clinical signs. Once a pet develops signs of paralysis, the antitoxin is not effective. 

Treatment of botulism in dogs is mainly supportive care. This supportive care can be time-consuming and expensive as it will require hospitalization, likely in an intensive care unit (ICU). 

Mildly affected dogs may be able to continue to eat and drink on their own with assistance, while more severely affected dogs will likely need IV fluids (to keep them hydrated) and feeding tubes. 

Care must be taken to provide sufficient bedding/padding and rotation of positioning to prevent an unmoving patient from developing bed sores.