I think tests were performed but there was controversy as to the results. It has been a long time since I have looked at the SAL cards but if I can locate a reference I will share.
Based on the information from http://www.amandaknoxcase.com/blood-evidence-downstairs-apartment/ there was no credible information disclosed about any scientific testing of the alleged cat blood. Interestingly, that site claims that Stefanoni testified that the cat left the blood after the police broke in. However, the video by the police shows bloodstains in a number of locations. Most curious is a nearly rectangular bloodstain with some suggestion of the outline of a knife blade on a bed (Bonassi's, IIRC).
The relevant lab records (“SAL’s”) were not disclosed until 2009, and then revealed that each of the 28 downstairs/outside Exhibits had been subjected to a presumptive test for blood (TMB), and 20 of the traces returned a positive result, indicating the likely presence of hemoglobin. The SAL characterized 18 of these as species-specific to “cat/gatto” but gave no further detail as to alleged species-specific blood testing. Curiously, Stefanoni testified that the “cat blood” had been deposited sometime after the police broke into the downstairs apartment, but before they collected the samples. Testimony by the residents of the downstairs apartment casts doubt on the theory that a cat been wounded sufficiently to have deposited all of the blood stains from downstairs/outside.
The question remains: were the downstairs samples really “cat blood”? The Scientific Police’s records are inconclusive and their actions suggest that they did not believe the samples were “cat blood”:
No species-specific blood test was observed by the defense, no methodology to identify species is disclosed in the SALs, and no corresponding test records have been produced.
The lab did not stop testing the samples that its records now say are “cat blood” (as would be expected if it believed it was dealing with cat samples), but instead, the lab subjected all of these traces to subsequent human-specific DNA analysis (Real Time PCR amplification and STR amplification).
The results of the Lab’s DNA testing undercut the suggestion that a species-specific blood test was performed, leading to a proper identification of all of the blood-positive samples as “cat blood”:
Only 2 of the 18 “cat blood” traces failed to quantify at least some human DNA.
Of the 20 blood-positive traces, 8 had sufficient quantity of human DNA such that, per the Lab’s practice, they could be genetically profiled. Of these 8 traces, the Lab records suggest that at least 6 were genetically-profiled (via STR analysis), but none of the ensuing 6 profiles have been disclosed by the prosecution.
It is implausible that some of the items identified as “cat blood”would actually have been deposited by a cat or that a cat could bleed from the ear that much:
Item Nos. 8, 9 and 10 form a path of 10 apparent freshblood drops leading down the steps to the entry door to the downstairs apartment. The number and placement of drops appears too profuse to be from a cat. In addition, the drops are wide and diffuse, suggesting that they might not represent drops of pure blood, but rather, blood thinned with water.
Item No. 28 is a lightswitch on the wall of the downstairs apartment. The lightswitch samples are the only blood samples from inside of the downstairs apartment that are not identified as cat’s blood.
The blood samples and their arrangement in the bedding may be too profuse to have been deposited by a cat.