FieldDxTetanusClinical signs, differential diagnosis, treatment and prevention in sheep, dogs, cats and horses.
Overview
A frequently fatal neurotoxic disease following wound contamination, especially deep or contaminated wounds in horses and lambs. Clostridium tetani, a soil-dwelling spore-forming bacterium producing a potent neurotoxin in anaerobic wound conditions. Marked emergency in FieldDx. Zoonotic: this condition can pass to people.
Clinical signs
- Spasm of the head muscles causes difficulty grasping and chewing food (‘lockjaw’).
- Horses: ears erect, tail stiff and extended, nostrils dilated, a rigid ‘sawhorse’ stance.
- Sheep, goats and pigs often collapse with opisthotonos when startled; consciousness is not affected.
- Dogs and cats often develop localised stiffness in a wounded limb before any generalised signs.
Predisposing factors
- Deep puncture wounds are the classic entry point for Clostridium tetani, carried in soil and the intestinal tract.
- In lambs and other young stock, often follows docking or castration where technique is not clean.
Treatment
- Drain and clean the wound; give penicillin or a broad-spectrum antimicrobial.
- Tetanus antitoxin — in horses, 300,000 IU IV every 12 hours has been used; see the separate Tetanus Antitoxin drug entry for other species.
- Sedation and muscle relaxants; nurse in a quiet, darkened space.
Drugs mentioned: Tetanus Antitoxin Penicillin G Penicillin V
Prevention
1. Toxoid vaccination. Kids/lambs should be vaccinated before or immediately after castration or disbudding. 2. A booster toxoid dose after a new, dangerous wound in an already-vaccinated animal.
Source
MSD Veterinary Manual — Tetanus in Animals (accessed 2026-08-10)
A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goat by ELSEVIER — Tetanus
Condensed and attributed, never reproduced whole. Open the full entry in the app.