[Hemophilia A in a male cat with intermittent lameness]

A 3-month-old domestic shorthair tomcat born on a farm was unsuccessfully treated with meloxicam for alternating lameness, fever and inappetence. On presentation, there was lameness (grade 2/4) of the right forelimb with mild swelling of the soft tissue. Rectal temperature was 39.9°C, a moderate anemia developed. Inadequate bleeding occurred during arthrocentesis performed on suspicion of polyarthritis. Coagulation tests revealed an isolated prolonged activated partial thromboplastin time (aPTT). Activity of factor VIII was 5% (reference range: 70-125%), of factor IX 55% (80-130%), and of factor XII 73% (50-140%).In a genetic study, exons and adjacent intron sequences of the feline F8-gene were sequenced and compared with the reference (ENSFCAT000078256.1). While no non-synonymous variants were found in coding sequences, intron 19 revealed the variant c.6073+2 T>C. This variant likely results in splice site alteration, atypical splicing, and thus an altered mRNA for FVIII.The patient was treated symptomatically (metamizole, buprenorphine, tranexamic acid) and clinical signs improved. Chemical castration with a GnRH implant was performed at 8 and 18 months of age, whereby minor bleeding at the implantation site occurred after the second implantation. After 3.5 years, the cat lives nearly without clinical signs of bleeding.aPTT prolongation with normal PT indicated a factor deficiency. Determination of factor activity led to the diagnosis of hemophilia A. Genetic testing detected a splice variant in the F8-gene.