Tetanus

What is Tetanus?

Tentanus is an infectious bacterial disease characterised by localised or generalised muscle spasms. The spasms are due to a neurotoxin produced by Clostridium tetani. Initially the bacterial spores enter a deep or penetrating wound. Germination occurs in the wound and bacteria then produce a neurotoxin that enters nerve cells and travels through spinal cord.

The neurotoxin may enter the central nervous system via three potential routes.

(i)   By ascending via the spinal cord.

(ii)  Spread of the toxin through blood circulation and passage through the blood-brain barrier.

(iii) Ascent via the cranial nerve axons.

The neurotoxin interferes with the nerve inhibition impulses from getting to the 'lower motor nerve cells' once it reaches the central nervous system. Such interferences cause spasms of the muscle.

The overall prevalence of tetanus in dogs is much lower than that in horses and human. This may be due to the relatively susceptibility of horses and human to the neurotoxin.

What are the Clinical Signs of Affected Dogs?

It may take 5 to 10 days for dogs to show clinical signs after the Clostridial spores have entered the wounds. Clinical signs vary according to the severity of the infection and are particularly worsened by noise and excitement. Those signs demonstrated by severely affected dogs include:

(i)   Lateral recumbency with rigidity of all limbs.
(ii)  Hypertension of the neck and difficulty in opening the mouth.
(iii) 'Tragic' facial expression.
(iv)  Seizures.
(v)   Respiratory failure causing death.

Clinical signs shown by dogs with less severe infection include:

(i)   Stiff gait.
(ii)  Elevated tail.
(iii) Erect ears and retracted lips.

A presumptive diagnosis of tetanus may be made based on the clinical signs and a history of having a deep or penetrating wound 5 to 10 days before.

Can Cases of Tetanus be Treated?

It is important to immediately limit the production and spread of neurotoxin once tetanus is suspected for successful treatment. Management of tetanus cases includes administering of tetanus antitoxin, cleaning, flushing and debriding of the infected wound, administering of antibiotic like penicillin, and provision of intravenous fluids.
 
The dog must be kept in a dark, quiet and undisturbed environment and receive minimal handling. Muscle relaxants are sometimes required to control the muscle spasms, rigidity and anxiety. If the dog survives, noticeable improvement generally occurs within 7 to 10 days and complete recovery takes place in about 4 weeks.

Does the Dog Require Routine Vaccination Against Tetanus?

Routine vaccination of dogs against tetanus is not generally recommended due largely to the low incidence of tetanus in dogs.