Blood Clotting Ability in Dogs with Immune Mediated Hemolytic Anemia (IMHA)



To evaluate blood clotting ability in dogs with immune mediated hemolytic anemia (IMHA).


Thromboembolism (inappropriate formation of blood clots) is a common and often fatal consequence of canine immune mediated hemolytic anemia (IMHA). Dogs with IMHA have mortality rates up to 80%, making this a serious and often fatal disease. Many of the deaths can be blamed on thromboembolic complications. Recent research has been unsuccessful in identifying why dogs with IMHA are prone to thromboembolism. Studies using a blood clotting test, called thromboelastography (TEG), have shown that dogs with IMHA have increased blood clotting activity. However, results of TEG are greatly influenced by low red blood cell numbers, or anemia, which is present in all IMHA dogs at diagnosis. Therefore, the presence of anemia can cause errors in TEG results. A more accurate way to measure blood clotting ability in IMHA dogs and other patients with anemia is needed. Calibrated automated thrombogram (CAT) is a new test of blood clotting used in human medicine. There are few veterinary studies describing the use of CAT. The OVC Comparative Hemostasis Laboratory has recently acquired the equipment to perform CAT. The first phase of this study will generate a reference interval for CAT results in healthy dogs. This will allow the test to be used in dogs with illness and blood clotting disorders, to determine if their CAT results are abnormal when compared to healthy individuals. The second phase of this study will determine if CAT is a better test of blood clotting ability in dogs with IMHA, compared to TEG. No such studies have been described yet in veterinary medicine, making the information gained in this research a novel addition to the literature. It is hoped that through this research, we will be better able to determine why dogs with IMHA are prone to thromboembolism. This knowledge will help lead to improved treatment and survival of dogs with IMHA.


  • Study covers cost of complete blood count upon study enrollment, 24hrs later and day of hospital discharge

Samples required

  • Blood (day 0, day 1 and day of hospital discharge)

Inclusion Criteria

  • IMHA diagnosis
  • Complete blood count consistent with IMHA (anemia plus spherocytes)
  • Presence of autoagglutination/positive Coomb's test
  • Platelet count >100,000 x109/L

Exclusion Criteria

  • Treatment with corticosteroids or anticoagulants for longer than 24 hours
  • Blood product transfusion within last 2 weeks


Dr. Shauna Blois (PI)

Dr. Benoit Cuq (DVSc. student)



Dr. Shauna Blois
Work #: 519-824-4120 x54419; Email:

Vicky Sabine, PhD
Clinical Research Coordinator
Email:; Work Cell #: 226-218-0338

Funded by OVC Pet Trust