Azoturia:

Syn: Monday morning sickness, Paralytic Myoglobinuria, Tying Up, Equine Exertional Rhabdomyolysis

• It is metabolic disease of horse occurring during exercise after a period of rest on full ration.
• It is characterized by muscle degeneration, Myoglobinuria, stiff gait, lameness, swelling, and hardening of skeletal muscles

Etiology:

• Overloading of carbohydrate, excessive production of lactic acid
• B₁ deficiency
• E and Se deficiency

Pathogenesis:

Horses on full ration during rest period results in excess storage of glycogen in muscle.

During exercise, after a period of rest, muscle glycogen is rapidly converted to lactic acid due to hypoxia

Lactic acid cannot be cleared by blood and gets accumulated in muscle

Lactic acid produces toxic effect on muscle causing coagulation and degeneration

Muscle becomes hard, stiff, swollen and Myoglobinuria occurs.

Clinical Signs:

• Signs develop 15-60 minutes after beginning of exercise.
• Profuse sweating, stiffness in gait, reluctant to move
• Horse assumes a dog-sitting position followed by lateral Recumbency
• Accelerated weak pulse, rapid respiration, and temperature may rise upto 40.5°C
• Hardboard like muscles- particularly of hindlegs (gluteal and quadriceps)
• Horse voids dark-red brown urine (Hburia).

Treatment:

• Avoid further exercise, give rest to animal.
• Supportive treatment; Massage of limbs by hot application
• IV injection of large quantities of fluids and electrolytes to maintain urine flow.
• Dexamethasone IV in large doses @2-5 mg IV or IM
• Thiamin (Vitamin B₁) @ 0.5-1 gm IM or IV
• NSAID; Flunixin @1ml/50 kg, b.wt., OD. It may be repeated upto 5 days
• Avil or Phenergan @ 10-15 ml, IV or IM
• E + Selenium mixture injection @1ml/50 kg, b.wt. It is repeated at 5-10 days’ interval.