The rete mirabile of the tail, an effective site for sampling sterile blood from armadillos (Dasypodidae, Xenarthra)

Armadillos constitute a neotropical endemic mammalian group in the American continent and the main diversity is distributed in Argentina. Several species of this family are in danger of extinction. Blood collection in armadillos is difficult because of their anatomy. In the present work, in latex-perfused material, the rete mirabile of the coccygeal artery of the tail was recognized as an appropriate venipuncture site for sterile blood collection. From cadaveric material, histological sections of the tail of six species of five genera of armadillos were used to determine the diameter and the distance to access the main artery of the rete mirabile ventrodorsally. Field studies were carried out in wild animals. A total of 232 blood samples were obtained from the following species: Chaetophractus villosus (70), C. vellerosus (105), Zaedyus pichiy (15), Euphractus sexcinctus (8), Dasypus hybridus (25), and Tolypeutes matacus (9). The animals were restrained with the thumbs pressing the abdomen ventrolaterally and the rest of the fingers holding the carapace. Punctures were carried out between the first and second rings of the tail with a 21-gauge needle. Alternatively, an immobilization device was designed to allow sampling by a single operator. Blood cell integrity was evaluated through histological analysis and ulterior development in lymphocyte culture. We concluded that the rete mirabile of the tail of armadillos is an effective venipuncture site for field studies that allows obtaining sterile blood samples, avoiding animal mortality, high-risk venipuncture sites, anesthetics and excessive stress.