Tetanus in Dogs

What is Tetanus in Dogs?

Tetanus in dogs is caused by a toxin produced by a bacteria called Clostridium tetani. This toxin targets the central nervous system (such as the nerves, spinal cord, and brain) and causes muscle spasms and hyperactive behavior. 

Dogs exposed to the bacteria through an open wound produce the toxin, usually through a deep puncture wound. Tetanus spores are widespread in the environment and can survive for months or even years in soil. These spores do not cause a problem if they are eaten or land on the skin. Instead, they cause infection when they bury themselves deep in the body where there is not enough oxygen. This is when they are able to “wake up” and start producing the toxin. 

This poison, called tetanospasmin, will find the central nervous system, usually, a nerve near the site of the injury. From there, it travels up the nerve, reaching the spinal cord and eventually the brain. Symptoms are possible anywhere the toxin is present as it travels through the dog’s body. Typically, signs of the disease start within 5-10 days of the wound occurring, but signs can show up as early as 3 days after exposure or as late as 3 weeks after the poison enters the system. 

Symptoms of Tetanus in Dogs

There are two forms of tetanus in dogs: the localized form (which is the most common) and the generalized form.  

In the localized form of the disease, signs develop primarily in the area closest to the wound. The muscles may become tight, stiff, and tremors may develop. Sometimes an entire leg may be affected. The localized form of the disease may sometimes become a generalized form of the disease. 

The generalized form of the disease is more severe and affects widespread areas of the body.  These animals may walk in a very stiff fashion, with their tail held straight up or straight out behind them, or if the muscles are so stiff they cannot bend their legs, they will stand with all four legs rigidly extended. This is called the “sawhorse” stance. 

Sometimes the area around the face and head is most severely affected, with the animal holding their lips back in a “sinister smile” and the jaws held tightly closed. Because of this, tetanus is often called lockjaw. Affected animals may be unable to swallow, leading to trouble eating or drinking, along with excessive drooling. If the muscle spasms affect the throat or the muscles that control breathing, respiratory distress can result. Because so many muscles are contracting and generating heat, these dogs may develop a fever. 

How Veterinarians Diagnose Tetanus in Dogs

In most cases, veterinarians can diagnose tetanus based on physical exam findings. This is a much simpler process if there is a wound present to support the suspected diagnosis. Although there are tests that are available to test for the toxin or C. tetani bacteria, these tests can be unreliable and are generally not recommended. 

Your veterinarian may also perform some basic screening tests to look for additional potential issues, including bloodwork, a urinalysis, and x-rays. Depending on the situation, other tests may be recommended. 

Treatment of Tetanus in Dogs

If the disease is caught early an antitoxin treatment may reduce its severity. However, once the poison has attached to the nerve cells, the antitoxin is no longer effective and may cause more side effects than benefits.   

For most animals, antibiotics are appropriate. Antibiotics do not directly affect the toxin, but if the underlying bacteria can be killed, it will stop the release of additional toxin into the dog’s system. This reduces the severity of the disease and allows the body to fight the remaining toxins. 

If your vet finds a wound, they will likely want to surgically debride the wound, or clean it out. This includes removing all tissue in and around the wound to remove as much C. tetani bacteria as possible, which reduces the amount of toxin being produced. 

Dogs with tetanus require very intensive medical care. Often, they are placed on intravenous fluids (IV) and medications for extended periods of time. Post-surgery, if they are unable to eat on their own, they may require a feeding tube. Most dogs require a significant amount of nursing care in a quiet, dark environment that reduces stimulations which may trigger muscle spasms. Medications can be used to try and reduce these spasms, but these have potential side effects and will need to be used with caution. 

Recovery and Management of Tetanus in Dogs

Dogs with the localized form of tetanus typically recover with time and early treatment, but it could take a month or more for all signs to resolve. For dogs that are more severely affected, or that have the generalized form of the disease, the prognosis is much worse, with survival rates as low as 50%. The quicker the diagnosis and the more aggressive the supportive care, the better the prognosis. 

The best way to prevent tetanus in dogs is to monitor your dog for any fresh wounds and seek appropriate care immediately. Proper cleaning of the wound (often under sedation if the wound is deep) is important to remove any bacteria. Following up with antibiotics for these deep wounds is also critical. If your dog develops any signs consistent with tetanus, reporting these immediately to your veterinarian is key. Rapid, appropriate treatment is lifesaving in cases of tetanus.