Thrombocytosis in 24 horses (1989-1994).

The study assesses the risk factors associated with thrombocytosis in horses, which were presented to the Veterinary Teaching Hospital of North Carolina State University College of Veterinary Medicine between 1989 and 1994. It found a strong link between thrombocytosis and inflammatory disorders/infections in horses.

Research Approach

• The researchers examined the records of horses presented between January 1, 1989, and April 30, 1994, to identify any associated factors with thrombocytosis – a condition characterized by high platelet counts.
• Out of 2,346 horses which underwent complete blood count (CBC), 1.0% had a platelet count that exceeded 400,000/microL.
• The demographic, diagnostic, physical examination, and clinicopathologic data were collected from these cases for comparison. A reference population was created involving 189 horses with a normal platelet count during the same period.

Findings

• Horses with high platelet counts were found to have infectious or inflammatory disorders more commonly than those with normal platelet counts.
• The initial independent evaluation of demographic variables showed that horses older than 3 years, females, and geldings were less likely to develop thrombocytosis than younger ones or stallions.
• Additional analysis of clinicopathologic variables indicated that horses with thrombocytosis were more likely to suffer from hyperfibrinogenemia, leukocytosis, hypoproteinemia, and anemia than horses with normal platelet counts.
• The study also noted that tachycardia (fast heart rate) and pyrexia (raised body temperature) were physical examination parameters associated with thrombocytosis.
• In the final multivariable model, the factors most strongly linked to thrombocytosis were leukocytosis, anemia, and hyperfibrinogenemia.

Implications

• The study concluded that thrombocytosis rarely results in clinical problems in horses and doesn’t generally need specific antiplatelet therapy.
• However, the strong relationship between thrombocytosis and infectious/inflammatory disorders may prompt clinicians to consider these types of conditions in cases of horses with high platelet counts.