The clotting cascade is a complex interaction of numerous protein and other factors that allow blood to clot after an internal or external stimulus. Deficiencies in clotting factors may be congenital or acquired, and lead to either an increased risk of bleeding or blood clot formation. In cats, several congenital coagulopathies have been described, including the Vitamin K responsive coagulopathy of Devon Rex cats, the clinically insignificant Hageman trait, and others. This case series described the occurrence and inheritance of a novel coagulopathy of Maine Coon cats in the United Kingdom.
The index case was an 8 month old Maine Coon who presented for uncontrolled hemorrhage 6 days after castration. On coagulation testing, PT, PTT, and TCT were indefinitely prolonged and fibrinogen was undetectable. The hemorrhage spontaneously ceased and the cat was discharged, but died one month later of pulmonary hemorrhage. On investigation, two of this cat’s littermates had also died of hemorrhage.
To investigate this condition blood samples were collected from Maine Coon cats over several years; both from healthy Maine Coons and from cats related to the affected cats. Cats were stratified into three groups: 1) cats with clotting abnormalities; 2) healthy cats related to cats with clotting abnormalities; and 3) healthy cats unrelated to coagulopathic cats.
All blood samples received a full CBC with manual film review, PT, PTT, TCT, measurement of factors VIII, IX, XI, and I. If sufficient serum was available, factors II and X were assessed.
Thirty-four cats were recruited to the study, however one died of pathologic hemorrhage before blood samples could be attained. Eight cats were recruited to group 1, thirteen to group 2, and twelve to group 3.
Cats in group 1 had a higher PT than groups 2 and 3, which were not different from each other. PTT was not significantly different between groups. TCT was significantly higher in groups 1 and 2 than in group 3. Fibrinogen was significantly lower in group 1 than in groups 2 and 3, and was lower in group 2 than groups 3.
The authors conclude that a genetic congenital fibrinogen deficiency exists in Maine Coon cats. The presence of an ‘intermediate” phenotype (group 2) suggests that it may be incompletely penetrant. (MRK)
Sparkes AH, Papasouliotis K, Mardell E, et al. Hypofibrinogenaemia causing bleeding problems in two cats. Birmingham: Proceedings of the BSAVA Annual Congress, 2003.