Reversible protocols of chemical restraint in wild capybaras (Hydrochoerus hydrochaeris)

Abstract

The Brazilian Spotted Fever can cause infection with severe clinical condition and lead to death if not treated properly. The capybara (Hydrochoerus hydrochaeris) is considered an important amplifier of the disease in nature, which makes it necessary to control their population and the deferentectomy technique has been shown to be the most appropriate. For this purpose, animals must be restricted chemically and the use of dissociative anesthetics, widely used, have shown a series of limitations and contraindications. This project aims to compare different chemical restraint protocols and their total and partial reversal. It is expected that one or more protocols will be effective in the immobilization of free life capybaras for fast procedures and its reversal will promote a quicker return to its environment, enabling the management of a greater number of animals in a safer way. Fifty six animals will be used, which will be divided into two groups (n=28), and subjected to one of the following protocols: dexmedetomidine (0,02 mg/kg) + midazolam (0,5mg/kg) + butorphanol (0,1 mg/kg) (DMB) or methadone (0,3mg/kg) (DMM), IM. Each group will be divided twice. First, 50% of the animals will receive supplementation of 100% of O2 and the other 50% will receive ambient air. In the second division, after 40 minutes of recumbency, 50% of each subgroup will receive flumazenil (0,02 mg/kg) + atipamezole (0,1 mg/kg) + naloxone (0,04 mg/kg) for full reversal and the other animals will receive only flumazenil and atipamezole. Thus, eight subgroups will be formed (DMB-O2-Completo, DMB-O2-Parcial, DMB-Ar-Completo, DMB-Ar-Parcial, DMM-O2-Completo, DMM-O2-Parcial, DMM-Ar-Completo e DMM-Ar-Parcial) with seven capybaras each. During the immobilization the heart and respiratory rate, temperature and noninvasive pressure will be monitored, as well as blood gases and electrolytes. The duration and quality of immobilization phases will be evaluated based on behavioral scales. The most efficient and secure protocol will be used, in combination with local block techniques, to perform deferentectomy.