Tetanus is an illness that can follow a wound. It is caused by a toxin made by the bacterium Clostridium tetani. The toxin acts on the nerves that control the muscles, so the muscles become stiff or go into spasm, and this can get worse with excitement, noise or touch [2]. A toxin is a poison.
If your dog or cat gets stiff near a wound, in a leg, the jaw or the neck, see your vet. If your pet has muscle spasms or trouble breathing, see your vet now.
How a wound leads to tetanus
The CDC explains that tetanus spores are common in the environment, including soil, dust and manure, and that they get into the body through broken skin [4]. In its guidance for people, deep puncture wounds and wounds dirtied with soil, feces or saliva, such as animal bites, carry the most risk [3][4]. A puncture wound is a small, deep hole, such as from a bite or a sharp object.
Once inside, the bacteria multiply mainly in the infected wound and release their toxin there [2]. The wound is not always easy to spot: in a study of 27 cats with tetanus, vets found no wound at all in a few of them [1].
For more on deep bite wounds, see bite wounds in dogs and cats.
When signs start
Signs usually follow a wound or wound infection by days or weeks [2]. So stiffness can appear after a wound already seems fine.
Dogs and cats resist it, but it still happens
Dogs and cats are much less sensitive to the tetanus toxin than horses and people [2]. Cats are even more resistant than dogs, which is one reason tetanus is reported less often in cats and tends to stay in one part of the body [1].
Early signs near the wound
In cats, the first sign owners noticed was most often a lame or stiff leg, and in most of those cats the wound was on or near that leg [1]. A typical sign was that the cat could not bend the worst-affected leg [1].
In dogs, early signs are often in the face: the lips pulled back, a clenched jaw, ears held up, small pupils and the third eyelid showing across the eye [2]. The third eyelid is a thin extra eyelid in the inner corner of the eye.
Signs as it spreads
Tetanus can spread from one area to more of the body. In the cat study, signs got worse in most cats and spread to other limbs in many, usually reaching their worst within about a week [1].
Dogs with more spread may walk with a stiff gait, stand with their legs braced like a sawhorse, hold the tail stiff and up, and have trouble swallowing [2]. They can be very sensitive to noise, light and touch, and severe cases may have muscle spasms or seizures [2].
Breathing problems are the most serious risk. Spasm of the larynx, the voice box, can block the airway, and food or saliva breathed into the lungs can cause pneumonia [2].
How vets diagnose it
There is no single lab test that confirms tetanus in a living animal [2]. Vets mainly rely on the typical signs and a history of a wound in the days or weeks before [2]. Tell your vet about any wound your pet has had, even one that has healed.
Treatment
Your vet will advise on treatment for your pet.
At home, as directed by a vet:
- do not open, squeeze or drain a wound yourself;
- do not give your pet human or leftover medicines unless your vet says so;
- follow your vet’s care instructions exactly;
- go back for any recheck your vet books.
When to see your vet
See your vet if your dog or cat has:
- a stiff or lame leg, especially near a wound [1];
- a clenched jaw, lips pulled back or ears held stiffly up [2];
- great sensitivity to noise, light or touch [2];
- a stiff walk, a stiff raised tail or trouble swallowing [2];
- any wound or stiffness you are unsure about, even if the wound has healed.
See your vet now if your pet has muscle spasms or trouble breathing [2].
The bottom line
Tetanus is caused by a toxin from bacteria that get into wounds. In dogs and cats it can start as stiffness near the wound, in a leg, the jaw or the face, and signs can start days or weeks after the wound. Only a vet can confirm it.
This article is for general information only and does not replace advice from your veterinarian. If your pet gets stiff near a wound, see your vet.
Sources
- Dussaux A, Fuhrer L, Dorner MB, et al. Clinical findings and outcome in feline tetanus: a multicentric retrospective study of 27 cases and review of the literature. Frontiers in Veterinary Science, 2024 (CC BY 4.0). https://pmc.ncbi.nlm.nih.gov/articles/PMC11286588/
- Dörfelt S, Mayer C, Wolf G, et al. Retrospective study of tetanus in 18 dogs: causes, management, complications, and immunological status. Frontiers in Veterinary Science, 2023 (CC BY 4.0). https://pmc.ncbi.nlm.nih.gov/articles/PMC10651760/
- About Tetanus. Centers for Disease Control and Prevention (CDC). https://www.cdc.gov/tetanus/about/index.html
- Tetanus: Causes and How It Spreads. Centers for Disease Control and Prevention (CDC). https://www.cdc.gov/tetanus/causes/index.html