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AFAST and the AFS system were prospectively studied in 49 traumatized cats. Although 17% of cats had positive fluid scores, feline “large‐volume bleeders” were almost nonexistent and those with an AFS of 3 and 4 died during triage or were dead on arrival and not enrolled (Lisciandro 2012). Originally, the conclusion was that AFS was less reliable in cats, but several years of experience suggest that AFS for bleeding works just as well in cats. However, bluntly traumatized cats generally do not survive large‐volume bleeds as dogs might (Mandell and Drobatz 1995; Lisciandro 2012). This is likely because the canine spleen serves as a large reservoir of blood whereas the feline spleen does not. Moreover, cats have over the years presented with “soft” positives at multiple AFAST views that would be better scored as a ½ rather than a full 1. The modification of the AFAST‐applied AFS system thus recategorizes more accurately these feline cases as “small‐volume bleeders” (Figure 7.8).

Figure 7.8. Example in a cat using the modified AFS system. (A) AFAST in right lateral recumbency and the four AFAST views used for the AFS. In (B) small triangulations (½ + ½ + ½) are found at three of the four views which calculates as an AFS of 1.5, a “small‐volume bleeder/effusion.” In (C) there are larger pockets of free fluid (1 + 1 + 1) at the same three AFAST views as in (A) and the AFS calculates as 3, a “large‐volume bleeder/effusion.” In (D) there are small triangulations at the DH and SR views and a larger pocket at the HRU view with a calculated AFS of 2 (½ + ½ + 1), a “small‐volume bleeder/effusion.” The same concept is applied to dogs.

Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.

Pearl: Cats with automobile‐induced traumatic hemoabdomen are often nonsurvivors before making it to veterinarians because they cannot compensate as dogs do and because of their smaller size, making injury more severe and lacking a splenic blood reservior. Free fluid on AFAST in surviving cats (>12–24 hours) is more likely to be urine than blood.