[Antithrombin III activity in health cats and its changes in selected disease]

Measurements of the antithrombin III (AT III) activity in feline plasma with a thrombin dependent chromogenic substrate assay using an automatic analyzer showed a high within run precision. The coefficient of variance was 1.82% (normal AT III activity) or 3.19% (decreased AT III activity), respectively. In comparison with the feline pool plasma the AT III activity in canine plasma was similar (93.7%) and in human reference plasma was lower (71.7%). Respecting healthy cats aged more than three months no distinct influence could be demonstrated on the AT III activity neither of age nor of gender (p = 0.2180). Based on the 2.5%- and 97.5%- quantile the reference range was 83.5-122.5% respecting the total number of healthy cats (n = 138) or 82.6-121.5% concerning the 116 European Shorthair cats. AT III activity of cats infected with feline immunodeficiency virus (n = 37) or teline leukemia virus (n = 20) as well as of cats suffering from different solitary tumors (n = 8) was not distinctly different from the control group (p > 0.05). On the contrary, a significant decrease of AT III activity was found in traumatized cats (n = 20; median = 80.8%, p < 0.0001) as well as in animals with chronic renal failure (n = 20; median = 91.7%, p = 0.0228) which can be mainly attributed to a consumption reaction or excessive renal loss, respectively.