The observation of reactive thrombocytosis in New Zealand white rabbits inresponse to experimental Pasteurella multocida infection

Reactive thrombocytosis is an increase in the circulating thrombocyte count secondary to a physiologic process within the body, often an infection. Re active thrombocytosis is different than primary or essential thrombocytosis which is usually related to myeloproliferative neoplasia, Essential thromb ocytosis is most common in adults, whereas reactive thrombocytosis is most frequently observed in children. Reactive thrombocytosis has been occasiona lly reported in cats, dogs and horses but has not been previously reported in the rabbit. Rabbits were challenged with virulent Pasteurella multocida. Hematologic, clinical, and culture assessments were performed prior to cha llenge, enabling each animal to serve as its own control. The questions ask ed were whether reactive thrombocytosis was a consistent phenomena and whet her its presence and/or intensity was related to disease severity. All chal lenged rabbits demonstrated some degree of thrombocytosis in response to th e infection, but individual rabbits were varied in their pattern of thrombo cytosis. Elevations varied from intense to mild to undulating with duration s of 1 to 11 days above 500x10(9)/L and 0 to 5 days above 650x10 degrees/L. Correlation analysis was unable to demonstrate significant association bet ween thrombocytosis, body temperature, leukocyte count, or the granulocyte lymphocyte ratio (all r < 0.2), No significant association between intensit y of thrombocytosis and degree or type of pathologic lesions was observed. Thrombocytosis does not appear predictive of disease intensity or outcome. The data indicate that in the rabbit thrombocytosis is a consistent respons e to infection with P. multocida, Rabbits may serve as a model for the stud y of reactive thrombocytosis, in humans especially in children infected wit h Haemophilus sp,, which are also a members of the bacterial family Pasteur ellaceae. (C) 1999 Academic Press.