Veterinary Clinical Medicine-II

CLINICAL SIGNS OF HYPOMAGNESEMIC TETANY

Acute

• Cease to graze, posture of unusual alertness, twitching of muscles and ears.
• Severe hyperesthesia - even a slight disturbance can precipitate attack, continuous bellowing, frenzied galloping.
• Staggering gait
• Falls with tetany of limbs, clonic convulsions, nystagmus, champing of jaws, frothing at the mouth, pricking of ears, retraction of eyelids
• The animal lies calm between episodes frequently, but sudden noise or touch precipitates another attack.
• Temperature - 40 to 40.5^ºC.
• Pulse and respiratory rates increased.
• Intensity of heart sounds audible at some distance from cow.
• Death in ½ - 1 hr.
• Mortality is high.

Sub acute

• Gradual onset - 3 to 4 days.
• Inappetence.
• Wildness of facial expression.
• Exaggerated limb movements.
• Resist being driven.
• Spasmodic urination and defecation.
• Decreased milk yield .
• Ruminal movements decreased.
• Wild tetany of hind legs and tail showing unsteady, straddling gait, retraction of head and trismus.
• Sudden movement, noise, restraint and injections can precipitate violent convulsions.
• May recover spontaneously within days or the disease progress to a stage of recumbency.
• Treatment is usually effective with marked tendency to relapse.

Chronic

• Serum Mg decreased
• No clinical signs, but sudden death.
• Few animals show vague syndrome - dullness, unthriftiness (more obvious syndrome), indifferent appetite and reduced milk yield.
• Paresis / milk fever like syndrome (in lactating cattle) but not responding to Calcium treatment.
• May also occur from the sub-acute form.