Introduction

The objectives of this study were to describe different treatment protocols, survival to discharge, and relapse in dogs diagnosed with primary immune-mediated thrombocytopenia (IMTP).

Methods

A retrospective observational study was conducted. A search of computerized records of a university teaching hospital was performed for dogs diagnosed with IMTP between January 2010 and January 2022. The inclusion criteria were a complete medical record and severe thrombocytopenia (<50000 platelets) with no evidence of an underlying cause found on investigations. Patients were excluded if they were treated with immunosuppressive medications in the 48 hours prior to presentation. Data collected included signalment, clinical signs, results of initial diagnostic tests, treatment, reason for treatment choice, survival to discharge and relapse. Due to small group sizes, a statistical analysis was not possible.

Results

A total of 54 dogs were included. Their age ranged from 1.2 years to 15 years (mean 7.7). Mean hospitalization time was 6.3 days (range 2–19). Choice of treatment was at the discretion of the attending clinician. All dogs received glucocorticoids. Six of all dogs (11%) received only glucocorticoids, 66.7% (36/54) received a second immunosuppressive agent, 79.6% (43/54) received vincristine and 22.2% (12/54) received intravenous immunoglobulins. The majority of dogs (19/54, 35.2%) were treated with a combination of glucocorticoids, vincristine and mycophenolate. In 16/19, both mycophenolate and vincristine were started within the first 48 hours. When stated, the most common reasons for adding a second immunosuppressive agent to the treatment were lack of response to current treatment and perceived severity of the clinical signs. Twenty-nine dogs (53.7%) required one or more blood transfusions. Forty-two dogs (77.8%) survived to discharge. Of the patients that survived to discharge, 4 (11.4%) experienced a relapse.

Conclusions

The majority of dogs in this study received a second immunosuppressive agent and vincristine early in the course of treatment. The choice of treatment was mainly based on clinician preference and on subjective assessment of disease severity. Future prospective studies are required to determine which treatment protocol reduces length of hospital stay, improves outcome and prevents relapse.

E-mail: stefania.gelendi@gmail.com