Transient Non-Regenerative Anemia in a Dog with Granulomatous Meningoencephalitis Following Leflunomide Treatment

A 10-year-old, spayed female Maltese dog was tentatively diagnosed with granulomatous meningoencephalitis (GME) on magnetic resonance imaging. The meningoencephalitis was classified as aseptic GME because cerebral fluid analysis did not reveal an infectious aetiology. Two months after leflunomide treatment (Arava; Sanofi; 4 mg/kg/day), the patient developed non-regenerative, macrocytic, and normochromic anemia. As the patient’s anaemia began after the administration of leflunomide, and other differentials for anaemia had been ruled out, the leflunomide was determined to be the cause and this treatment ended. After 15 days, the anaemia resolved spontaneously. This is the first report of reversible aplastic anaemia following treatment with leflunomide in a canine patient with GME.