Tetanus in Goats (Clostridium tetani Infection)

Etiology

Pathogenesis

1. Is taken up by peripheral motor nerve terminals
2. Travels retrograde to the spinal cord and brainstem
3. Blocks release of inhibitory neurotransmitters (glycine, GABA) at inhibitory interneurons
4. Results in failure of inhibition of motor reflex responses
5. Leads to generalized spastic (rigid) paralysis - simultaneous contraction of agonist and antagonist muscles

Entry Points in Goats

• Castration (especially elastrator banding - creates deep anaerobic pockets)
• Kidding/dystocia - uterine/vaginal wounds during difficult births
• Disbudding/dehorning - open wounds near the horn base
• Ear tagging and tattooing
• Umbilical stump infections in neonatal kids
• Dog bites, fight wounds, puncture wounds
• Tethering lesions - chronic skin wounds from neck ropes
• Foot wounds - foot rot, interdigital injuries

Elastrator band castration is considered higher risk than open surgical castration because it creates a closed, oxygen-poor environment where spores thrive.

Incubation Period

• Typically 10-20 days, but can range from a few days to several months
• Shorter incubation = more severe disease (toxin closer to CNS)

Clinical Signs

• Rigid, stiff gait
• Mild bloat (tympany)
• Anxiety, nervousness
• Stiffness of the jaw muscles (trismus/lockjaw)
• Changed/altered voice (muffled bleat)

• Lockjaw - inability to open the mouth, drooling of saliva
• Sawhorse stance - all four limbs rigidly extended, resembling a rocking horse
• Erect ears and stiff, elevated tail
• Prolapse of the third eyelid (nictitating membrane) across the eye
• Fixed stare, wide eyes
• Flared nostrils
• Neck stiffness with head pulled back (opisthotonus)
• Hypersensitivity to sound, light, or touch - any stimulus triggers spasms
• Constipation, urinary retention

• Convulsions
• Respiratory muscle spasm - apnea, asphyxia
• Lateral recumbency with limbs rigidly extended
• Death (from respiratory failure or aspiration)

Diagnosis

• History of a recent wound, castration, kidding, or surgical procedure
• Characteristic signs: trismus, sawhorse stance, third eyelid prolapse, opisthotonus
• Hypersensitivity to external stimuli

• Hypomagnesemia (grass tetany) - no wound history
• Polioencephalomalacia - central signs predominate
• Listeriosis
• Rabies
• Strychnine poisoning
• Meningitis/encephalitis

Treatment

1. Wound Management

• Identify and thoroughly clean/debride the wound
• Remove necrotic tissue; create aerobic conditions
• In band-castrated males with late-presenting tetanus, surgical removal of the band/scrotum is recommended to eliminate the toxin source

2. Neutralize Circulating Toxin

• Tetanus Antitoxin (TAT) - passive immunization using equine-derived antibodies
  • Prevention dose (high-risk, unvaccinated animal): 1,500 IU
  • Treatment dose (active disease): 3,000-15,000 IU, regardless of body size
  • Must be given early - ineffective once toxin is bound to neural tissue
  • Note: equine-origin TAT can cause anaphylaxis; have epinephrine ready

3. Kill the Organism

• Penicillin G (procaine or aqueous) - drug of choice; kills C. tetani at the wound site
• Metronidazole - an alternative/adjunct; highly active against anaerobes
• Continue for 7-10 days

4. Sedation / Muscle Relaxation

• Diazepam (Valium) or acepromazine - reduces muscle spasms
• Phenobarbital or xylazine can also be used
• Keep the animal in a dark, quiet environment - minimize sensory stimulation

5. Supportive Care

• Fluid therapy - IV or oral via stomach tube; animal cannot drink due to lockjaw
• Nutritional support - nasogastric tube feeding may be needed
• Bloat management - pass a stomach tube carefully (do NOT give mineral oil - it can be aspirated)
• Turn the animal every 30-60 minutes if recumbent - prevents pressure sores and hypostatic congestion
• Corticosteroids (e.g., dexamethasone) may reduce inflammation
• The Pharma Journal case report documented full recovery in 3 days with fluid therapy, penicillin, and dexamethasone in a post-kidding goat

Prevention

Vaccination (most effective measure)

• Tetanus toxoid (often combined with Clostridium perfringens C & D = CD&T vaccine)
• Primary course:
  • Dose 1 at 1 month of age
  • Dose 2 at 2 months of age (4-6 weeks later)
• Annual boosters for all adults
• Pregnant does: Booster 2-4 weeks before kidding - transfers passive immunity to kids via colostrum
• Kids from vaccinated does receive maternal antibody but still need their own primary course

Tetanus Antitoxin (TAT) for at-risk unvaccinated animals

• Give at the time of castration, disbudding, or any major wound in unvaccinated goats
• Provides temporary passive immunity for 7-14 days

Good Management Practices

• Use surgical (open) castration rather than elastrator bands where possible
• Maintain clean, hygienic facilities
• Disinfect all wounds, ear tags, tattoo instruments
• Proper neonatal umbilical cord care (dip in iodine)
• Avoid tethering with ropes that cause skin abrasions

Prognosis