Clinical findings, treatment and outcome in cats diagnosed with precursor-targeted immune-mediated anaemia in a referral hospital in the UK: 30 cases (2010-2021).

Aims: This retrospective study aimed to report clinical findings, treatment response and survival in cats diagnosed with precursor-targeted immune-mediated anaemia (PIMA) in a referral hospital in the UK.

Methods: Feline cases diagnosed with presumed PIMA between January 2010 and February 2021 were retrospectively recruited. Signalment, clinical signs, diagnostic tests, treatment and outcome were recorded. Descriptive analytics were performed. Outcomes were documented according to survival to discharge, 30-day survival, total survival time, response to immunosuppressive treatment and frequency of relapses.

Results: Thirty cats met the inclusion criteria. A higher prevalence of females (19/30) was identified (p = 0.001). Most cats (25/30) presented with haematocrit below 0.15 L/L. Concurrent cytopenias occurred in 18 of 30 cats. Bone marrow diagnosis was erythroid hyperplasia in 24 of 30 cases. Survival to discharge was documented in 26 of 30 cats, of which 23 survived more than 30 days since diagnosis. Initial treatment included blood products (26/30) and prednisolone (26/30) or prednisolone with ciclosporin (3/30); 18 of 30 cats responded to treatment, with a normal haematocrit at a mean of 28 days. The initial haematocrit and the presence of concurrent cytopenia were not statistically different between responders and non-responders. The median survival time was 140 days (range 1-3930 days).

Conclusions and relevance: The treatment response rate of feline PIMA was high (60%), with a mortality rate of 23% over the 30 days following diagnosis. Relapses occur frequently (77%) but the response rate after treatment modification was high (76%) and therefore ongoing treatment may be justified at that point. Long survival times (up to 3930 days) can be achieved.