• Adverse reaction;
  • Platelet recovery time;
  • Platelets;
  • Vaccine


Vaccination is often cited as a potential cause of immune-mediated thrombocytopenia (ITP) in dogs. Although an association has been documented in humans, particularly in children, this relationship has not been definitively established in dogs.


To identify the presence of an association between recent vaccination and ITP in dogs.


Forty-eight client-owned dogs with presumptive idiopathic ITP and 96 age-matched, client-owned dogs with non-immune-mediated disease.


Retrospective, case-control study. Dogs were identified through the Veterinary Medical Database (VMDB) and Hospital Information System at Purdue University.


The median age at presentation for dogs with ITP was 7 years (range: 2–15 years). The majority of the ITP group was comprised of mixed breed dogs (38%); no pure breed was represented by more than 3 cases. The number of dogs that were vaccinated within 42 days of diagnosis of ITP did not differ significantly (P = .361) between cases of presumptive ITP (4/48, 8%) and the control group (13/96, 14%).

Conclusions and Clinical Importance

This study failed to confirm the presence of an association between presumptive idiopathic ITP in dogs and recent vaccination; however, the possibility of an association cannot be completely ruled out based on the small sample populations and requires further investigation.