Leptospirosis - Cattle and Sheep
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Description
Leptospirosis is an economically significant zoonotic disease caused by the bacteria leptospira interrogans. L. interrogans serovar hardjo is host-adapted to cattle; disease in cattle is usually due to L.pomona or L.hardjo. Clinical disease is rarely seen in sheep, they are less susceptible to the bacterium but may act as non-symptomatic carriers.
In cattle leptospirosis is seen in 3 forms, acute, subacute and chronic.
- Acute disease in susceptible heifers, with fever and agalactia of all quarters; abortion and stillbirth may occur
- Diagnosed by rising antibody titre in paired serum samples
- Infection in sheep may cause abortion and agalactia
- Urinary excretion can be reduced by administering dihydrostreptomycin or amoxycillin
- Incactivated vaccines are of questionable efficacy
- Serovars pomona, grippotyphosa and icterohaemorrhagiae cause pyrexia, haemoglobinurea, jaundice, anorexia, uraemia due to renal damage and death in calves and lambs
Signalment
Risk factors include access to rivers and watercourses, rodent infestation, buying in stock and using a bull instead of AI. Cograzing sheep with cattle can result in disease in cattle as sheep can act as non-symptomatic carriers.
Diagnosis
Clinical Signs
Acute syndrome:
- Pyrexia
- Anorexia
- Dyspnoea
- Hymolytic anaemia
- Icterus
- Haemoglobinuria
Enzootic/chronic form:
- Abortion
- Infertility
- Milk drop