Equine Health Unveiled: Decoding the Secrets of Veterinary Blood Tests

Dr. Mac Sheds Light on Essential Veterinary Blood Tests for Horses – A Closer Look at Diagnosis and Disease Prevention

Why do veterinarians collect blood samples from horses and what information do they seek? Dr. Mac provides an overview of this vital diagnostic process. When a veterinarian is called to examine a horse, it is common for them to use a needle to draw blood from the animal’s jugular vein. Typically, two samples are taken, each in a tube with different colored tops—one red and one purple.

The red-topped tube, which contains no additives, is utilized for assessing blood chemistry and diagnosing infectious diseases through serology, an examination of blood serum. On the other hand, the purple-topped tube contains an anticoagulant, preventing blood clotting, and is employed to check the haematocrit and perform blood smears.

The haematocrit, representing the percentage of red blood cells in the total blood volume, helps identify conditions such as anemia or haemoconcentration. Anemia, often caused by blood parasites like Babesia caballi or Theileria equi, can lead to babesiosis. Haemoconcentration, an increased proportion of red blood cells, is associated with life-threatening conditions requiring immediate veterinary attention.

Another essential test involves examining blood smears, which assess the quantity, type, and shape of white blood cells (leukocytes). A high white cell count indicates severe infection or allergy. Platelets, vital for blood clotting and produced in the bone marrow, may decrease due to certain diseases, toxins, or immune-related conditions, leading to thrombocytopaenia.

Blood samples are also subjected to biochemical tests to identify bacteria and viruses. The accompanying analysis document lists the required tests, with normal values provided. Diagnosis involves comparing test values to the norm; for instance, elevated urea and creatinine levels suggest kidney problems, while increased bilirubin and alkaline phosphatase are linked to liver failure.

In cases of muscle injury or disease, elevated levels of creatinine kinase (CK) and aspartate aminotransferase (AST) within six to eight hours indicate acute muscle damage. CK, prevalent in skeletal and cardiac muscle, is often assessed with AST in muscle damage evaluations. Elevated blood lactate levels may indicate colic in horses.

Blood samples can also be sent to a laboratory for rapid identification, using polymerase chain reactions, of genetic patterns associated with hereditary diseases and the presence of pathogens such as African horse sickness.