Systemic arterial pressures of spontaneously hypertensive rats (SHR) were not detectably different from control rats prior to 3 weeks of age. Arterial pressure was elevated in SHR at 4 weeks compared to Wistar-Kyoto rats. Thus, the term ‘prehypertensive stage’ should probably be reserved for animals less than 1 month of age when this model is examined.

The ability to safely and effectively manage reproduction is central to the success of AZA captive-breeding programs. Although the AZA Wildlife Contraception Center routinely monitors contraceptive safety, there have been no studies that compare the effects of contraceptive use to separation of males from females, the other option for preventing reproduction. We used retrospective medical records and pathology reports submitted by AZA and related facilities for the seven AZA-managed canid species to assess rates of uterine pathology relative to female reproductive life histories. Our results showed that the prevalence of both pyometra and endometrial hyperplasia (EH) was associated not only with treatment with the two most common contraceptives (Suprelorin® and MGA implants) but also with the number of years barren (i.e., not producing a litter and not contracepted). Rates of pyometra and EH were especially high in African painted dogs and red wolves, but lowest in swift and fennec foxes. The number of years producing a litter had a low association, suggesting it could be protective against uterine pathology. A more recently developed Suprelorin® protocol using Ovaban® to prevent the initial stimulation phase, followed by implant removal when reversal is desired, may be a safer contraceptive option. These results concerning the relationship between reproductive management and uterine health have important implications for AZA-managed programs, since the unsustainability of many captive populations may be due at least in part to infertility. Managing a female's reproductive lifespan to optimize or maintain fertility will require a reconsideration of how breeding recommendations are formulated.

This study examined the role of the anteroventral third ventricle (AV3V) in the renin-dependent two-kidney, one-clip model of renal hypertension. AV3V lesion and sham lesion rats were subjected to the placement of a clip on one renal artery or a sham operation. The sham lesion-renal artery clip rats experienced an increase in systolic blood pressure; however, AV3V lesioned animals experienced only a transient rise in arterial pressure during the 1st wk after clip. Body fluid regulation studies during the course of the hypertension revealed that there were no differences in water intake and urine volume between the lesion- and sham lesion-renal artery clip animals. Although significantly greater plasma and blood volumes were demonstrated in the AV3V lesion-sham clip rats compared with sham lesion animals, no differences in vascular volumes were detected in the renal artery clip rats. Finally, the rats were water deprived for 3 days to maximally stimulate vasopressin release. Urine osmolality increased significantly in all groups of rats except the AV3V lesion-renal artery clip animals protected against the hypertension.

The sea otter (Enhydra lutris) is a popular exhibit animal in many zoos and aquariums worldwide. Captive sea otters from these populations are owned by the United States Fish and Wildlife Service (USFWS). The USFWS has requested that these sea otters be prevented from breeding in order to save captive space for wild rescued animals. Sea otters are often housed in mixed sex groups, therefore a chemical contraceptive method or surgical removal of gonads must be used to prevent potential pregnancy. The contraceptive, Suprelorin® or deslorelin, has been used in many different species to effectively suppress reproduction but duration of effect may vary not only between species but also individuals. Here, we report the effects of one to several consecutive deslorelin implants on gonadal reproductive hormones found in fecal samples from six captive sea otters (two males and four females) compared to two control otters (one male and one female) housed at three zoological institutions. We documented the longitudinal hormone signatures of many stages of the contraceptive cycle including pretreatment (PT), stimulatory phase (S), effective contraception (EC), and hormone reversal (HR) that was characterized by a return to normal hormone levels. Deslorelin was found to be an effective contraceptive in sea otters and was found to be reversible documented by a live birth following treatment, however the duration of suppression in females was much longer than expected with a 6-month and a 1-year implant lasting between 3 and 4 years in females.

Contents North American zoos began using melengestrol acetate (MGA) implants to control reproduction in wild felids in the mid‐1970s. Research linking MGA and other progestin‐based contraceptives to uterine and mammary pathology in canids as well as felids resulted in a shift to GnRH agonist implants (Suprelorin®: deslorelin, Peptech Animal Health, Australia). However, a recent study revealed an association between Suprelorin® and uterine pathology in canids, but that pathology was not found in canids treated with oral megestrol acetate (MA) for 2 weeks around the time of implant insertion to prevent the initial agonist stimulation phase. Thus, the AZA Wildlife Contraception Center (WCC) currently recommends Suprelorin® plus the 2‐week MA regimen for wild canids and felids. WCC research is now focusing on factors affecting Suprelorin® reversibility.