Background: Since the discovery of the Mik antigen, several studies have described blood incompatibilities unrelated to the AB system in cats. Objective: To estimate the prevalence of cats with non-AB incompatibilities associated with naturally occurring alloantibodies (NOAb), and to begin mapping the corresponding feline erythrocyte antigens (FEA). Animals: Two hundred and fifty-eight type A cats. Methods: Prospectively, cats were evaluated for the presence of NOAb by crossmatching in groups of 4-6 cats. When NOAb were detected in a cat, its plasma was used as reagent to assess for the presence of the corresponding FEA in all cats included thereafter, and agreement observed between results of this extensive blood typing was evaluated. Results: The chance of detecting incompatibilities by randomly crossmatching 2 cats was 3.9%, which resulted in at least 7% of type A cats having NOAb. Blood typing and agreement analyses performed with 7 newly detected NOAb allowed the identification of 5 presumably distinct FEA. Feline erythrocyte antigens 1 and 5 were most frequent with prevalence of 84% and 96%, respectively. Only FEA 1-negative status was associated with a higher risk of presenting NOAb; with 16.7% of 42 FEA 1-negative cats having NOAb compared to 5.1% of 216 FEA 1-positive cats. Conclusions and Clinical Importance: This study represents a first step of FEA identification outside the AB system. Because of its prevalence and association with NOAb, FEA 1 might correspond to the Mik antigen.

Background In dogs with congestive heart failure (CHF), the efficacy of torasemide, a loop diuretic, has been demonstrated. However, unlike in dogs and humans little has been described about the use of torasemide in the cat with spontaneous CHF. The objectives of this retrospective study were therefore to describe the therapeutic use of oral torasemide in cats with spontaneous CHF, document its potential adverse effects while reporting the clinical course of this feline population following torasemide administration in addition to standard medical therapy. Results Medical records of 21 client-owned cats with CHF (median age = 10.6 years [interquartile range (IQR) = 6.5–11.2]) receiving torasemide were reviewed. Data collected included torasemide dosages, other concurrent medications, physical examination features, echocardiographic data, and potential adverse effects during follow-up. A survival analysis was performed to estimate the time from diagnosis to cardiac death. Dyspnea related to CHF was identified in all cats (pleural effusion [8/21], pulmonary edema [5/21] or both [8/21]), associated with ascites in 4/21 cats. The CHF cause was determined by echocardiography in all cats: hypertrophic (n = 10), restrictive (n = 6), arrhythmogenic right ventricular (n = 3), dilated (n = 1) cardiomyopathies, and aortic valve abnormality (n = 1). At initiation, median torasemide dosage was 0.21 mg/kg [IQR = 0.17–0.23] q24h. Clinical signs declined in most cats (20/21) during the first 2 weeks with no remarkable adverse events. Median survival time after torasemide prescription was 182 days [IQR = 46–330]. A contemporary control group including 54 cats with CHF, receiving furosemide as sole loop diuretic treatment was compared with the study group. Median (IQR) survival time of cats in the control group was not significatively different (p = 0.962) from that of the torasemide group, i.e., 148 days (9–364), although the torasemide group included significantly more cats with recurrent episodes of CHF (52%) that the control group (19%). Conclusions This case series demonstrates that torasemide can be used in cats with spontaneous CHF. This therapeutic interest needs to be confirmed by prospective clinical trials.