Do dogs need tetanus shots? We have all heard of tetanus. In fact, most of us have even received tetanus shots, but what about canine companions, do dogs get tetanus? Yes, dogs get tetanus, but no, they do not need tetanus vaccines. This is because dogs are more resilient to tetanus than humans. Humans and horses are particularly sensitive, while cats are extremely resistant. Dogs are somewhere in the middle – they can get tetanus, but on rare occasions.
Understanding the Tetanus Malady
Almost all warm-blooded animals can contract tetanus, a non-contagious infection caused by the bacteria Clostridium tetani. The bacterium thrives without causing disease in the horse’s intestinal tract and is found in soil contaminated by horse or cow manure.
Clostridium tetani usually enters the body through a deep, penetrating wound in the skin. Once inside the wound, in conditions where oxygen is lacking and the body’s tissue is decaying, the bacteria produce a poisonous chemical or toxin, called tetanospasmin. The tetanospasmin upsets the infected dog’s nervous system.
Signs of Tetanus in Dogs
What the signs of tetanus in dogs? The clinical signs may appear within a few days, but usually show up several weeks after the injury. The leg muscles of the affected dog may contract violently in random spasms. The limbs may extend in a rigid manner, and the jaws become locked – hence the common name for tetanus, which is lockjaw.
The mouth becomes difficult to open, and there is a characteristic "smile" caused by the muscular retraction of the lips and eyes. The forehead muscles contract, making the ears stand up, and the third eyelids may be more apparent. Death results from a combination of dehydration, breathing problems and general exhaustion.
Based on the severity of the signs, affected dogs can be classified in 4 different groups:
- Group I – the dog is able to walk, but it is unable to open its jaw, the pupils are constricted, the ears are erect, the eyes are sunk in and the dog is sensitive to light.
- Group II – the dog walks stiffly, the tail is erect, the dog takes a sawhorse stance and has difficulties swallowing.
- Group III – the dog is unable to walk and shows muscle tremors, spasms and seizures.
- Group IV – the dog’s heart rate switches from below 60 beats per minute to above 140 beats per minute, the blood pressure switches from low to high and ultimately the dog shows signs of respiratory arrest.
It should be well-noted that this condition has a tendency to progress really fast. A dog classified as group I can become group II, III or even IV in just a few days.
At the Vet's Office
Dogs suspected of having tetanus or showing signs, need to be promptly taken to the vet. Sadly, there is no specific test for diagnosing tetanus – no blood tests, no unique findings. More often than not, the diagnosis is based on the history of a deep wound and the dog’s overall appearance.
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Alternatively, one may try to culture the Clostridium tetani from the wound, but these attempts are usually not successful. Theoretically, the antibodies against the tetanus toxin can be measured. However, this approach is not regularly used.
It is important to spot the clinical signs early and to eliminate the possibility of strychnine poisoning, which causes similar symptoms.
What's the treatment for tetanus in dogs? The treatment of tetanus consists of two goals: killing the Clostridia and stabilizing the patient. Since the Clostridia tetani rod is a classic gram positive bacteria, it can be successfully killed with an antibiotic therapy. The antibiotic of choice is penicillin. Dogs that are sensitive to penicillin can be alternatively treated with tetracycline. Metronidazole is also effective but if used on a long-term basis it has more side-effects.
The second goal, stabilizing the patient, is trickier and it includes several aspects:
- Controlling the spasms and seizures – this is achieved through sedation. Acepromazine and chlorpromazine are frequently used. In addition of achieving sedation, they aid in managing the light and noise sensitivity.
- Reducing the muscle stiffness – diazepam, midazolam, propofol and phenobarbital are successfully used.
- Addressing the respiratory compromise – in cases of larynx spasm, the patient needs general anesthesia, an endotracheal tube and a mechanical ventilator.
- Minimizing the noise and light stimuli – it is recommended to have the patient placed in a darkened and quiet room.
- Managing the dehydration – intravenous fluid therapy is quite beneficial.
- Destroying the tetanus toxin – this can be achieved by using tetanus antitoxin. However, the use of this antitoxin is quite controversial. The antitoxin is a blood product derived from horse or human blood. It acts by binding with the toxin and inactivating it. However, the antitoxin cannot inactivate the toxin that is already bound with the patient’s nerves. It can only inactivate the toxin that is not yet bound.
The major risk associated with the use of this antitoxin stems from the fact that, as a blood product from a different species, it can be highly inflammatory and triggering to the host’s immune system. When used, it can be administered subcutaneously (s.c.) and muscularly (i.m.) or intravenously (i.v.). The s.c. and i.m. administration are safer in terms of triggering an anaphylactic reaction. However, if administered via these routes, the antitoxin needs up to 3 days to reach a therapeutic level.
The i.v. administrations warrant a much faster efficiency, but the risk of allergic reaction is also much greater. In the early stages of the disease, the antitoxin can be administered directly into the skin. This procedure is used to determine how reactive the patient is.
The prognosis depends on the dog’s stage classification at the time of treatment initiation. Complete recovery is possible, but it may take several weeks, so follow-up supportive care is essential.
Do Dogs Need Tetanus Shots?
As mentioned, unlike human beings, dogs have a naturally high resistance to Clostridium tetani. However, the risk of infection remains. Since there is no approved tetanus vaccine for dogs, routine vaccination is not undertaken. If your dog has been injured, always make sure that any wound is cleaned and disinfected thoroughly and promptly to stop the infection spreading. Early intervention by a vet can avoid death.
About the Author
Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia. She currently practices as a veterinarian in Bitola and is completing her postgraduate studies in the Pathology of Domestic Carnivores at the Faculty of Veterinary Medicine in Zagreb, Croatia.