February 23, 2026, 4:56 am | Read time: 5 minutes
If a dog suddenly has trouble swallowing, appears tense in the face, and seems unusually calm, many owners initially think of a harmless cause like an insect sting or teething. However, if the condition rapidly worsens and the facial expression becomes rigid, there may be more to it. Such early signs are easily misinterpreted. PETBOOK explains which symptoms should be taken seriously and why quick action can be crucial.
Overview
What Is Behind a Tetanus Infection?
Tetanus, also known as lockjaw, is a bacterial disease of the nervous system. It is caused by the bacterium Clostridium tetani. However, it is not the bacterium itself that is responsible for the symptoms, but rather a nerve toxin it produces, called tetanospasmin. This toxin is released after entering the body and specifically interferes with communication between nerves and muscles. This disrupts normal signal transmission, ultimately leading to the typical muscle spasms.
Normally, the nervous system ensures a controlled interplay of muscle tension and relaxation. Certain nerve cells have an inhibitory effect—they prevent muscles from remaining tense permanently. However, tetanospasmin blocks these inhibitory signals. As a result, the muscles remain constantly tense, leading to persistent muscle spasms and typical stiffness of the limbs.
After the toxin is produced in the wound, it travels along the nerves toward the spinal cord and brain. There, it binds to certain nerve cells and permanently blocks their function. This binding is irreversible—it cannot be undone. For the signal transmission between nerves and muscles to normalize again, the body must build new nerve connections. This process takes time, which is why a tetanus infection in dogs can last for several weeks.1
Causes of Tetanus in Dogs
Tetanus is caused by the bacterium Clostridium tetani. It is found worldwide, especially in moist soil, street dust, mud, and the feces of various animals. A notable feature of the bacterium is that it forms resilient spores that can survive in the environment for weeks or months.2
An infection almost always occurs through an injury. If spores enter a wound and oxygen-poor conditions prevail, they begin to multiply and produce the nerve toxin. Deep, poorly ventilated, or contaminated wounds are particularly susceptible. However, even small, initially inconspicuous injuries can serve as infection sites. These include:
- Bite and fight injuries
- Paw injuries from splinters, thorns, or nails
- Abrasions and scratches
- Postoperative wounds
- Small mucosal injuries, such as during teething
In general, mammals react differently to the tetanus toxin. Compared to horses, for example, dogs are considered significantly less sensitive. Nevertheless, the disease can be severe and life-threatening in dogs.
How Owners Can Recognize the Symptoms
The first symptoms usually appear three to 18 days after infection. Initially, the course of infection is often gradual but can rapidly worsen. Early signs often affect the facial muscles. Typical symptoms include:
- Stiff facial features
- Raised lips with a rigid expression (“sardonic smile”)
- Problems blinking
- Difficulty swallowing
- Increased salivation
- Stiff, cautious gait
- Hypersensitivity to light, sounds, or touch3
As the condition progresses, muscle stiffness can spread throughout the body, leading to:
- Generalized muscle rigidity
- Noticeably extended posture of the limbs (“sawhorse stance”)
- Difficulty standing up or lying down
- Stiffly carried tail
- Jaw muscle spasm with limited mouth opening
- Fever
- Increased pulse
- Breathing problems due to cramped respiratory muscles
If tetanus remains untreated, it can lead to respiratory arrest in severe cases.4
How Tetanus Is Diagnosed in Dogs
A definitive laboratory test for tetanus is usually not available in practice. Therefore, the diagnosis is primarily based on the typical clinical appearance.
Key factors for diagnosis include:
- Characteristic muscle changes
- The rigid facial expression
- Evidence of a previous injury
- Neurological examination
- Exclusion of other diseases with similar symptoms
The overall symptom picture usually provides the crucial clue.
Treatment
A tetanus infection is an acute emergency in dogs and requires immediate, intensive treatment. Once the veterinarian has made the diagnosis, tetanus is treated as follows:
- Wound care:
The wound is thoroughly cleaned. Contaminated or dead tissue is surgically removed. - Antibiotics:
Antibiotics are used to combat the bacterium. - Tetanus antitoxin:
In severe cases, an antitoxin may be administered to neutralize the circulating toxin. Its effectiveness is variably assessed in the literature. - Symptom control:
Muscle relaxants, pain relievers, and sedatives are used to control spasms. Infusions stabilize circulation and fluid balance.
Recovery can take four to six weeks. During this time, the tetanus toxin remains active.
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Prognosis
The chances of survival depend on several factors. The severity of the symptoms and whether vital muscle groups like the respiratory or heart muscles are affected are crucial. Additionally, the dog’s age and overall health play an important role. The timing of the start of therapy also significantly influences the course: The earlier the treatment begins, the better the prospects usually are.
Can Owners Prevent Tetanus in Dogs?
A routine tetanus vaccination, like in humans, is not common for dogs. Therefore, careful wound hygiene is of particular importance. Injuries should be cleaned as soon as possible and treated with an appropriate disinfectant. It is important to have deeper, contaminated, or poorly healing wounds examined by a veterinarian.
It is also advisable to regularly check the paws and mouth area, especially after fights, extensive digging, or during teething phases when small mucosal injuries can occur. The more consistently even small injuries are noticed and treated, the lower the likelihood of infection.