Vet Guide 2025: Tetanus (Lockjaw) in Dogs – Causes, Symptoms & Emergency Treatment 🧠🦷

Hi pet parents, I’m Dr Duncan Houston. Tetanus—also known as lockjaw—is a rare but potentially life-threatening condition in dogs. Caused by toxins from Clostridium tetani, it triggers severe muscle spasms. In this guide, we’ll review causes, clinical signs, diagnosis, treatment steps, survival rates, and what you can do if your dog may be affected. 🐶

What Is Tetanus?

Tetanus is a result of a toxin (tetanospasmin) produced by Clostridium tetani, an anaerobic bacterium commonly found in soil. The toxin travels via nerves to the spinal cord and brainstem, blocking inhibitory neurotransmitters (glycine, GABA). The result? Painful muscle rigidity, spasms, and—when severe—respiratory paralysis. Dogs show species-specific signs and generally resist toxins better than humans or horses.

Who Is at Risk?

• Dogs—especially those with deep wounds or punctures contaminated with soil, grass awns (e.g., foxtails), or animal bites.
• Cats are highly resistant and rarely affected; this guide focuses on canine tetanus.

How Dogs Get Tetanus

C. tetani thrives in oxygen-deprived environments—think deep puncture wounds, dirty surgical sites, or grass awn burrows. The toxin travels within nerve sheaths, reaching the central nervous system typically in 3–21 days (5–10 days average) post-injury. Early signs often include facial stiffness (locked muzzle, raised ears) and heightened sensitivity to stimuli—light clapping may cause spasms.

Recognizing the Signs

Symptoms often follow this progression:

1. Facial stiffness: Difficulty blinking, risus sardonicus (“sardonic smile”), erect ears, light/noise sensitivity.
2. Sawhorse stance: Rigid legs, stiff neck and back; may refuse to walk.
3. Advanced signs: Jaw locked shut, difficulty eating, trouble breathing, generalized muscle twitching or full-body spasms.

Dogs may initially show localized signs near the wound; this can spread systemically.

Diagnosing Tetanus

• No definitive test—diagnosis is based on history, signs, and wound examination.
• Blood tests for antibodies aren’t routinely used.
• Cultures rarely isolate C. tetani.

Treatment Overview

Key goals are to eradicate the infection, neutralize unbound toxin, control spasms, and provide supportive care.

1. Antibiotic Therapy

Stop bacterial growth using:

• Penicillin: Safe and effective against C. tetani.
• Metronidazole or clindamycin: Also options, especially with anaerobic coverage.

2. Toxin Management

• Tetanus antitoxin: Neutralizes circulating toxin but not toxin already bound within nerves. Must be skin-tested to avoid allergic reactions.
• Tetanus toxoid vaccine: Stimulates immunity but does not contain antibodies; not useful for acute cases.

3. Muscle Spasm Control & Sedation

Medications and supportive strategies:

• Acepromazine or chlorpromazine: Reduce sensory-triggered spasms and lighten external stimuli sensitivity.
• Benzodiazepines (diazepam, midazolam), barbiturates, or muscle relaxants (e.g., methocarbamol): Manage severe spasms. General anesthesia may be needed if respiratory muscles are compromised.

4. ICU & Supportive Care

• Calm environment: Dark, quiet, minimal stimulation.
• Feeding and hydration: Fear of aspiration may require slurries or tube support during “lockjaw.”
• Ventilation: Intensive respiratory support is essential if breathing muscles stiffen.
• Wound care: Surgical cleaning and debridement to remove necrotic tissue and foreign material (foxtails, etc.).
• Prevent secondary issues: Soft bedding, physical therapy, eye protection due to eyelid paralysis.

Severity Classification

A study of 35 dogs at UC Davis categorized cases as follows:

• Group I: Facial signs only (e.g., risus sardonicus, jaw stiffness) – walking normally.
• Group II: Additional stiff gait, erect tail, mild systemic signs.
• Group III: Muscle spasms, inability to walk, seizures possible.
• Group IV: Severe: abnormal blood pressure, respiratory arrest, critical.

Outcomes & Survival Rates

In the UC Davis study:

• 77% overall survival.
• 100% survival for dogs not progressing past Group II.
• About 50% survival for those in Group III or IV requiring intensive care.

Typical Recovery Timeline

Improvement often begins within the first week. Full recovery can take 2–4 weeks. Some dogs retain jaw stiffness or respond slower to triggers, but most regain mobility and function.

Prevention Tips

• Recognize and clean wounds early: Deep punctures from grass awns, broken glass, or animal bites are risk factors.
• Use sterile technique: Especially after surgeries or deep laceration repairs.
• Vaccination rationale: Routine tetanus toxoid is not standard for dogs (rarely affected), but may be considered in high-risk situations (e.g., foxtail ab airway migration).
• Breed predisposition: We haven’t seen specific breed susceptibility beyond common risk factors.

When to Take Action

Seek emergency veterinary care if your dog shows:

• Jaw stiffness (“lockjaw”) or facial spasm
• Light or sound triggering spasms
• Stiffness, inability to walk, breathing difficulty
• Drooling, difficulty eating, decreased appetite

We’ll begin treatment promptly to limit toxin effects and support your dog safely through recovery.

Case Example: Extreme Tetanus

A dog treated at the University of Florida for severe tetanus required mechanical ventilation and intensive sedation. With careful ICU care and supportive treatment, the dog made a strong recovery over several weeks.

Bottom Line

Tetanus is rare but serious in dogs. Prompt veterinary treatment—including antibiotics, spasm control, wound management, and intensive support—leads to a good prognosis in most cases. Prevention focuses on cleaning wounds quickly and understanding environmental risks like grass awns or deep bite wounds.

Stay alert to early signs like jaw stiffness or sensitivity to stimuli. With rapid intervention, your dog can bounce back from tetanus and live a full, happy life.

Dr Duncan Houston, BVSc