Clinical Signs & Symptoms

Acute signs:
Pyrexia – generally mild (fever)
Lethargy (weakness / loss of energy)
Anorexia (loss of appetite leading to weight loss)
Icterus (Jaundice – yellowing of the skin and eyes that is caused by too much bilirubin in the blood)
Haemoglobinemia (excessive haemoglobin in the blood)
Haemoglobinuria (dark red haemoglobin-containing urine)
Pale mucous membranes
Tachycardia (rapid heart rate)
Tachypnea (rapid breathing)

Additionally, sweating, colic, lacrimation, incoordination, cardiac murmurs, and subcutaneous oedema around the head and eyelids can occur.

Subacute cases are characterised by intermittent pyrexia, anorexia, tachycardia, tachypnea, with variable degrees of icterus, haemoglobinuria, and bilirubinuria.

Chronic infections typically result in variable clinical presentations involving anorexia, lethargy, and mild anaemia. Of the two causative organisms, B. equi is considered more pathogenic. A variety of secondary complications may result from Babesiosis including acute renal failure, colic, enteritis, laminitis, pneumonia, infertility, and abortion. In cases with suspect clinical signs of Babesiosis, the following differential diagnoses should be considered: Equine Infectious Anaemia (EIA), Monocytic Ehrlichiosis, Red Maple Toxicosis, and hepatic disease.

On rare occasions, a peracute form of the disease occurs. Horses can die within 24-48 hours of the onset of clinical signs.