Clinical and laboratory findings of a bleeding disorder in Simmental cattle.

Eight Simmental cattle were presented to the Western College of Veterinary Medicine over the past decade with historic or current prolonged episodes of bleeding. Spontaneous epistaxis, superficial hematomas, and prolonged bleeding following injury or minor surgery (such as tattooing) were frequent observations. Animals presented because of prolonged hemorrhage were anemic and debilitated. Compensatory erythropoiesis was compromised in these animals by depletion of iron stores due to chronic blood loss. Screening tests to assess coagulation were normal as were numbers and morphology of platelets. In vitro platelet aggregation was abnormal in all affected cattle. Three animals were euthanized due to uncontrollable hemorrhage but the precise source of hemorrhage was undetectable. These findings are consistent with bleeding due to a platelet function disorder which has been described previously in Simmental cattle.