Generally, most ectoparasites with good motility such as adult arthropods (various crustaceans, lice, fur mites, mosquitoes, ticks, etc.) will abandon the host carcass over the first minutes to hours, especially in birds and mammals where the dropping body temperature is a strong stimulus. Some parasites, however, are firmly or deeply embedded in the host skin and may be occasionally detected on a skin scrape after six hours, though they may be already dead. Importantly, knits, eggs, and feces of many ectoparasites will still be detected on the skin, on hair shafts, or within hair follicles. The answer really depends on the host species and parasite species of interest. In any case, the skin can be swabbed at 6 hours post-mortality using a sterile synthetic (e.g., dry flocked) swab that can be tested for multiple parasite species using real-time PCR.

Considering that skin scraping is performed to diagnose contagious diseases, if it is very important, because it must consider that the dead animal, allows the possibility of confirming the diagnosis and take measures to protect the rest of the animals, as well as the implementation of appropriate measures for the decontamination of the area in which the animal died, for what may be occupied by new individuals.

I agree with Dr. Crim