Assessment of a portable prothrombin time analyzer (CoaguChek-XS) in dogs.

Objectives - To assess the performance of a portable prothrombin time (PT) analyzer (CoaguChek-XS) in dogs. Animals - Ninety-seven dogs composed of 20 healthy dogs, 45 ill dogs, and 32 ill dogs with altered coagulation. Procedures - Samples were concurrently obtained and PT was measured using the CoaguChek-XS and an automated coagulation analyzer. Agreement between methods was assessed using Spearman's correlation and Bland-Altman analysis. Results - The reference interval for PT using the CoaguChek-XS was 9.6-11.5 s. The CoaguChek-XS was easy to use, required a small volume of whole blood, and gave results within 1 min. The mean difference in PT between the 2 methods was 2.58 s (SD 3.10), and 94% of the samples fell within limits of agreement. The correlation was moderate, but significant (r = 0.35, P < 0.001). Sensitivity and specificity of the CoaguCheck-XS PT compared to analyzer PT were 92% and 56%, respectively, and increased to 95% and 77% on intent to treat basis. The coefficient of variance was 0.72%. The CoaguChek-XS identified all 8 dogs with anticoagulant rodenticide intoxication, although a discrepancy was noted from the analyzer results. In anemic dogs (PCV <= 25%), the CoaguChek-XS did not display accurate results. Conclusions - The CoaguChek-XS is a simple, user-friendly, highly precise PT analyzer. Results had moderate correlation and good agreement with a standard method. It can be used reliably for screening dogs when the PT is normal. However, when the CoaguChek-XS PT is prolonged or when the PCV is <= 25%, results should be confirmed using a standard method.