Effects of Lupron and surgical castration on fecal androgen metabolite concentrations and intermale aggression in capybaras (Hydrochoerus hydrochaeris)

Abstract

To curb agonistic interactions in a bachelor group of three male capybaras (Hydrochoerus hydrochaeris), a single dose of leuprolide acetate (Lupron®) was used in an attempt to chemically sterilize the males. Concurrently, fecal androgen metabolite (FAM) concentrations were quantified via enzyme immunoassay to monitor changes in testosterone production after injection of the gonadotropin‐releasing hormone agonist. When Lupron proved ineffective in suppressing intraspecific aggression, surgical castration was performed on two males, with continued noninvasive endocrine monitoring. In all three capybaras, FAM concentrations increased initially as a result of the luteinizing hormone surge, but then decreased significantly following chemical sterilization. Surgical castration resulted in further, persistent declines in FAM concentrations in two males, while the third, intact male demonstrated a rise in FAM to pre‐Lupron concentrations at 8.5 and 9.5‐month postadministration. Despite successful suppression of sperm and testosterone production, intermale aggression continued, ultimately necessitating separation of the animals and transfer to other holding institutions. Under this set of conditions, a single Lupron dose was inadequate for suppressing intraspecific aggression in a group of three males with a pre‐established history of aggression.

Surgical contraception of free‐ranging female capybaras: Description and comparison of open and minimally invasive techniques

“…(C) Suspension of the left ovary by the uterine tube, after removing the intestine. (D) Topography of the right uterine tube when the procedure is performed on the opposite side; kidney (9) and intestines (10). (E) Blunt divulsion of the mesosalpynx (ms) to isolate part of the uterine tube (ut).…”

“…Removing the 5); stomach (6); small (7) and large (8) intestines. (G) Small intestines reflected to expose de right ovary (9); bladder (10) caudally reflected to expose the uterine body (11). (H) Stomach reflected to expose the left ovary (12) excised uterine tube segment through the 5 mm portal was performed unremarkably.…”

“…However, these studies have only addressed males. The consequences of gonadectomy on the social behavior of male capybaras are still uncertain 10 and have never been studied in females. By contrast, the use of deferentectomy and salpingectomy does not seem to cause social changes in the group 12 and in this sense they are still considered acceptable surgical options for the sterilization of capybaras.…”

“…4 It is territorial and forms family groups that have a strong social hierarchy. 5 In contrast with other wild animals, [6][7][8][9] there are a few recent reports on hormone therapy use 10 or immunocontraceptive methods 11 in capybaras. However, these studies have only addressed males.…”

Comparative statistical analysis of the release kinetics models for nanoprecipitated drug delivery systems based on poly(lactic-co-glycolic acid)

“…For instance, for long-term administration formulations, the time of permanence in blood varies between 24 hours (i.e. Lupron ® , AbbVie Inc. [ 49 ]), 4 weeks (Lupron Depot ® , AbbVie Inc. [ 50 ]), 12 weeks (Lupaneta Pack ® , AbbVie Inc. [ 51 ]), to 24 weeks (i.e. Triptodur ® , Arbor Pharmaceutics [ 52 ]).…”