Just like people, dogs that are critically ill or hospitalized are at a heightened risk of blood clots. Yet veterinarians have few reliable tools to diagnose animals that are prone to developing a potentially life-threatening clot.

To help in the process of identifying high-risk dogs, a team of clinicians from Penn’s School of Veterinary Medicine evaluated the medical records of hundreds of dogs treated at Penn Vet’s Ryan Hospital. Their analysis revealed that a commonly performed blood test often used to identify patients at risk of bleeding may also be used to identify those predisposed to clot excessively.

“I think based on this retrospective study, we should pay more attention to shortened clotting times and look at them with a degree of diagnostic value,” says Deborah Silverstein, senior author on the study, which was published in the Journal of Veterinary Emergency and Critical Care, and an associate professor of critical care at Penn Vet. “In this patient population of critically ill dogs, it may help in identifying patients at risk of thrombosis.”

The research, conducted together with former intern Jennifer Song and Kenneth J. Drobatz, a professor of critical care and director of emergency services at Penn Vet, looked specifically at the results of two blood tests commonly used to measure a dog’s ability to clot: prothrombin time, or PT, and activated partial thromboplastin time, or aPTT. Animals with results that are longer than normal are considered at risk of abnormal bleeding. However, when a clotting time was shorter than normal, clinicians have typically dismissed it as due to a sampling or handling mistake.

The new study took a closer look at patients with shorter PT and aPTT times, also looking at their medical records for indications of a clinical finding of hypercoagulability, a tendency for blood to clot excessively.

They found that more dogs with shortened PT and aPTT times had clinical signs of hypercoagulability and suspected pulmonary thromboembolism compared to a control group of hospitalized dogs with normal clotting times.

Though the results are from a relatively small group of animals, Silverstein thinks they are compelling enough for clinicians to consider further diagnostic tests and even anti-coagulant treatment in certain high-risk patients with a shortened PT or aPTT.