Among humans, tetanus is quite a scary possibility when wounds become contaminated, but can dogs get tetanus from stepping on a rusty nail as it happens in people? This question is a good one considering that tetanus is a serious condition that can even lead to death if not treated on time. Tetanus shots for dogs are not popular in veterinary medicine as in human medicine, and there's a good reason why: tetanus is overall a rare condition in dogs. However, rare doesn't mean impossible, so following is some information about tetanus in dogs.
A Potent Neurotoxin
Tetanus, also known as lockjaw, is a medical condition that is caused by exposure to a potent neurotoxin that affects the muscles. This neurotoxin is created by the body by Clostridium tetani, a spore-forming bacteria that can be found in the environment, particularly in rich soil and manure, but also in dust and saliva. Once in the environment, the bacteria, can stick around for quite long period of times by forming spores.
How does a person or dog becomes infected? The bacteria, present in the environment, in particular in the soil and manure, enters the body courtesy of cuts (open wounds or even cuts in the mouth associated with teething) or puncture wounds (from nails, barb wire or animal bites) that become contaminated with such soil. Once the bacteria are in the body, they form potent neurotoxins (tetanospasmin) which can travel from the wound to nerves at distant sites.
These toxins block the inhibitory transmission to motor neurons, which means that they interfere with the correct functioning of muscle contractions causing motor neuron disturbances. In simple words, the neurotoxin interferes with the signals that the brain sends to tell muscles to relax. This leads to several of the tell-tale signs that are seen in tetanus.
Symptoms of Tetanus in Dogs
If your dog stepped on a rusty nail, don't expect for signs of tetanus to show up right away. Clinical signs of tetanus tend to occur generally anywhere between 5 days to 3 weeks after the injury. The signs may start from the area of injury and then gradually spread to the entire nervous system.
In localized tetanus, the affected dog will therefore first develop stiffness of a muscle or of the entire leg that's wounded. Afterward, as the condition progresses, the stiffness will spread to involve the whole body including the tail. The dog affected with tetanus will hold the ears erect (even if the ears are normally floppy), and the facial muscles may be drawn in what is medically known as "risus sardonicus"a staple sign of tetanus that makes the dog appear as if he is grinning.
Affected dogs may also develop increased salivation, abnormal heart and respiratory rates, laryngeal spasms, trouble swallowing, regurgitation and gastroesophageal reflux. Because dog can't open the mouth well and have trouble swallowing, they are often unable to eat. Additionally, the dog's third eyelid may show, the muscles of the dog's jaw may develop spasms, hence the term "lockjaw" which is also known by the medical term "trismus." Mild stimulation such as sudden movements or noises may lead to repeated episodes of contractions of the muscles of the whole body, hyperextension (opisthotonus) and convulsions. Left untreated, death can arise from respiratory failure.
Tetanus in Dogs
As mentioned, tetanus in dogs is quite rare and that's why vets do not vaccinate for tetanus as it happens in people and horses. Tetanus is also quite rare in cats too. A potential reason behind this is that cats and dogs may have evolved to better cope with puncture wounds associated with fighting and are therefore better capable to fight off the disease, explains veterinarian Dr. Matt Allworth.
While tetanus is not very common in dogs, if your dog has stepped on a rusted nail or got hurt from barb wire, an animal bite or some other way, preventing an infection is something you may need to be more concerned about.
See your vet as some wounds may require you to start your dog on antibiotics so to lower the chances for an infection to set in. As first aid, you should clean the wound with warm water and then can apply some plain neosporin until you can take your dog to the vet, suggests veterinarian Dr. Christian.
Another thing to consider is that there are a variety of conditions that can cause symptoms that are similar to tetanus in dogs. Possible differentials include strychnine intoxication, organophosphate poisoning, meningitis, polymyositis rabies or hypocalcaemia (low calcium levels).
"Yes, dogs can get tetanus. However, they are naturally resistant, and tetanus infections are very rare. We do not immunize dogs for tetanus. There are no approved tetanus immunization for dogs." ~Dr. Laura Devlin, Veterinarian
At the Vet's Office
Your vet will take a detailed history asking about your dog's symptoms and wounds. At the current time, there is no test that provides definite diagnosis of tetanus in dogs. Isolating clostridium tetani from a wound is unfortunately difficult to do and often unrewarding.
Diagnosis of tetanus in dogs is generally made through history of a recent wound and the clinical signs which are often quite characteristic of tetanus. Relying on the presence of a wound as proof of potential tetanus though is not enough considering that it is possible that, the owner has not noticed it, or by the time tetanus symptoms set in, the wound has already healed up.
The vet may run a complete blood count to check for signs of infection and serum biochemistry profile to look at the numbers of muscle enzymes. In particular, creatinine kinase (CK) and aspartate aminotransferase (AST) may show significantly increased numbers due to the sustained muscle contractions. X-rays may also show signs of complications that are possible with tetanus such as presence of megaoesophagus or aspiration pneumonia.
Dog Tetanus Treatment
Antitoxin, which uses an antibody of another animal to destroy the tetanus toxins within the dog’s body, can be administered through an IV, but precautions must be taken to prevent allergic reactions and potential anaphylaxis, but its efficacy remains uncertain. Some vets may decide to first test for reactions by giving an injection under the skin. If there are chances for allergic reactions, vets will administer an antihistamine. If a reaction develops, the vet may need to administer steroids or epinephrine.
Antibiotics (penicillin G, tetracyclin, metronidazole) may be given through a vein or in a muscle to help rid of any clostridium tetani organisms still present in the wound. Supportive care may include sedatives for excitable dogs, fluids for hydration, thracheostomy for laryngeal spasms, muscle relaxants and gastric tubes if the muscle spasms prevent the dog from eating. In some cases, toe amputation may be needed if there is presence of severe nail bed infections.
In mild cases, where there are no abnormalities in heart rate or blood pressure values, affected dogs return to normal functions, possibly weeks after treatment is started, but in severe cases, the prognosis is guarded and dogs may die from respiratory and cardiovascular dysfunction. Due to the extensive costs associated with hospitalization for several weeks, many dogs are euthanized due to the owner's financial constraints.
Viewer Discretion Advised: Micky, Tetanus in a Dog. This story has a happy ending.
- Clinical Practice, Companion Animals, Diagnosis and treatment of generalised tetanus in dogs by Anne Fawcett and Peter Irwin
Tetanus in the dog: review and a case-report of concurrent tetanus with hiatal hernia, Els Acke, Boyd R Jones, Rory Breathnach, Hester McAllister, Carmel T Mooney, Ir Vet J. 2004; 57(10): 593–597. Published online 2004 Oct 1