What is your diagnosis? A feline blood smear

Abstract

A 2‐year‐old female spayed domestic shorthair cat was referred to the Ontario Veterinary College Health Sciences Centre (OVC‐HSC) for evaluation of vomiting, lethargy, anorexia, and icterus. The cat was current on vaccinations, and together with two other healthy cats, was adopted from South Africa 1 month prior to presentation. Seven days before referral, the cat was evaluated at the referring veterinarian for vomiting, at which time the cat was treated with maropitant, milbemycin oxime, and metronidazole. One day before referral the cat was re‐presented due to a reoccurrence of the vomiting. A gastrointestinal diet was prescribed, and blood was submitted to a diagnostic laboratory for a CBC and serum biochemistry profile (ADVIA 120 Hematology System analyzer and Olympus AU640 Chemistry Analyzer). On the day of referral, the cat was icteric, depressed, and acutely anorexic. The previously submitted CBC and biochemistry results showed a macrocytic, hypochromic, markedly regenerative anemia (hematocrit 0.19 L/L, reference interval (RI) 0.29‐0.48 L/L; mean corpuscular volume 77 fL, RI 37‐61 fL; mean cell hemoglobin concentration 297 g/L, RI 300‐380 g/L; absolute reticulocytes 418 × 10/L, RI <45 × 10/L), increased alanine aminotransferase (1533 U/L, RI 31‐105 U/L) activity, pancreatic lipase (PrecisionPSL, 193 U/L, RI 8‐26 U/L) activity, and total bilirubin (38.7 μmol/L, RI 0‐4 μmol/L) concentration. On testing, the cat was seronegative for feline leukemia virus (FeLV) antigen (ELISA) and feline immunodeficiency virus (FIV) antibody (immunofluorescent antibody assay; both tests completed by Antech Diagnostics Canada Ltd. Mississauga, ON, Canada). On physical examination at the OVC‐HSC, the cat was dull but responsive, tachycardic (300 bpm), tachypneic (60 bpm), pyrexic (40.0°C), and had pale icteric mucous membranes. A CBC performed at admission revealed a macrocytic, hypochromic, regenerative anemia, and leukocyte and platelet concentrations within RIs (Table 1). A blood smear was reviewed (Figure 1). Results of a direct antiglobulin test (DAT) by microtiter plate technique were negative at a dilution of 1:2 (Veterinary Medical Research & Development, Pullman, WA, USA).