Abrasion index
The abrasion index is a diagnostic option in veterinary medicine to determine whether a pig population is infected with Sarcoptes mites ( Sarcoptes scabiei var. Suis ) ( mange ).
Usually about 20 animals are observed for 15 minutes. Every time an animal scratches it is noted. In the end, the number of scratches is divided by the number of animals and the so-called abrasion index is calculated.
If this is higher than 0.4, it is possible that the animals are sick with the mange, which should be checked by a veterinarian. From an index of 1.5 it is considered certain that the mange is in the stock. An abrasion index below 0.4 is no evidence that the population of Sarcoptes mites is free.
The diagnosis of mange by means of the abrasion index shows only a low specificity, however, since the scratching behavior of the animals can be triggered by a wide variety of causes. Different environmental conditions as well as social behavior and housing conditions play an essential role here. It should also be borne in mind that not only sarcoptic mites but also other ectoparasites such as B. Lice and flies can lead to an increase in itching.