Azoturia: Pathogenesis , Diagnosis and treatment

Synonyms

  • Paralytic Myoglobinuria
  • Paralytic Haemoglobinuria
  • Black Water
  • “ Typing Up “ myositis
  • “Monday Morning ” Sickness

Introduction:

Tying Up/ Azoturia - Agnew Equine
  • It is a disease of horse, occurring during exercise after a period of inactivity on full ration.
  • This is characterized by myogloglobinuria and muscle degeneration.
  • In most instances there is history of a period of complete inactivity for 2 or more days immediately preceding the onset of the disease.
  • Generally on Sunday animals are kept at rest with full quantity of good grain diet. Since the animal has not to face exhaustion and exercise and remain inactive ,the ration is not utilized fully and major parts of grain remain stored in muscle as glycogen.
  • On Monday, during exercise the problem starts with the onset of the disease. So, the disease is most commonly known as “ Monday Morning Disease”.

Aetiopathogenesis

A Review of Exertional Rhabdomyolysis in Wild and Domestic Animals ...
  • When exercise is taken after a period of inactivity the glycogen stored in the muscles is rapidly metabolized to large amount of lactic acid due to anoxia.
  • If the rate of production exceeds the rate of excretion, accumulation of lactic acid occurs rapidly and highly in the muscle as sarcolactate.
  • The space between the individual muscle fibres is filled with lactate.Since lactate is very much toxic, muscles become swollen leading to muscular degeneration and coagulation of muscle proteins.
  • There is profound formation of myoglobin due to the degenerative changes of muscle and also due to anaerobic condition of muscle.
  • Due to this myoglobin comes out in the blood stream and ultimately excreted through urine.
  • This is called myoglobinuria and urine is red broun in colour.
  • Coagulation necrosis of muscle fibres occurs which causes hard, stiff and painful swelling in the muscle.
  • The gluteal muscle are most commonly affected due to their high content of glycogen.(Condition Known as myopathy)
  • Due to neuropathic degeneration of the heavy muscle , animal is unable to stand and lie down to sternal and lateral recumbancy.
  • Prolonged recumbency leads to ulcers on skin.
  • Death is usually due to decubital septicaemia or myohaemoglobinuric nephrosis and uraemia.
  • In some case,degeneration of myocardium ( cardiopathy) may also be the cause of death.

Clinical Findings:

Azoturia in Horses: Causes, Clinical Signs and Treatment
  • Signs develop within 15 minutes to 1 hr after the beginning of exercise, which need not be vigorous.Thus even only simple walking may cause this condition.
  • There is sudden cramp of the muscles of hindquarters. Muscles become stiff, hard and boardlike.
  • Severe pain and distress are accompanied by stiffness of the gait, struggling, restlessness and repeated attempts to raise.
  • Rapid respiration with abnormal pulse.
  • Profuse sweating
  • In later stage, temperature may raise to 105ºF.
  • Urine is coffee or deep red brown coloured.
  • Appetite and water intake are often normal.

Diagnosis

  • By History:

History of a period of complete inactivity.

  • By clinical findings :
  • Clinical Pathology:

Presence of myoglobin in Urine. Myoglobin in urine can be differentiated from haemoglobin by Spectroscopic examination.

Differential Diagnosis

  • Laminitis:

No discolouration of urine.

  • Haemoglobinuria :

Absence of local pain or lameness. Generally caused by infective agent( Bacteria, protozoa, toxic plants, snake venom etc)

  • Vit E or Selenium Deficiency:

Muscular dystrophy, absence of myoglobinuria.

  • “ Typing Up “ Syndrome:
Understanding and Managing Tying Up and Rhabdomyolysis in the Horse

Mild paralytic myoglobinuria. Abdomen become hard, tucked up due to colic. But, rectal palpation would indicate obstructive substances.

  • Illiac Thrombosis:

It can be detected on Rectal Palpation.

Line of Treatment:

  • All the possible steps should be taken so that animal is able to stand.
  • Narcosis with chloral hydrate may be necessary if pain is severe or the makes repeated efforts to rise.
  • Corticostereroids are to be administered intravenously.
  • Antihistamines evoke success in early stage.
  • Vit B1 should be administered as it helps in lactate metabolism.
  • Vit. E and selenium is also recommended.
  • Urine should be kept alkaline to avoid precipitation of myoglobin in renal tubules. So alkanizer like Sod. Bicarbonate @60g b.i.d orally or 2.5% sod. Bicarbonate can be injected IV route.
  • Sometimes 25% solution of calcium borogluconate IV gives good result.
  • Autohaemotherapy.

Prevention and Control measures

Azoturia in Horses: Causes, Clinical Signs and Treatment
  • Regulated Exercise.
  • Horse should be provided with half of its grain ration during rest period while no exercise is made.
  • Ration of horse should be according to nature of its work.
  • Carbohydrate intake should be monitored properly.
  • The serum enzyme of race horse should be monitored as a guideline to measure the muscle damage.

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