Oral and injectable synthetic progestagens effectively manipulate the estrous cycle in the Przewalski's horse (Equus ferus przewalskii).

To date, there has been limited research on manipulation of the estrous cycle in endangered equids. The objectives of this study were to assess the efficacy of using combinations of: (a) oral altrenogest and PGF2α, and (b) injectable altrenogest and PGF2α for manipulation of ovarian activity in Przewalski's mares. Reproductive cycles were monitored by assessing follicular changes with rectal ultrasound and changes in urinary steroid hormones. In Study 1, five cycling mares were treated with oral altrenogest (n=11 cycles) for 14 days. In Study 2, cycling mares were treated with oral altrenogest for 12 days (n=5 cycles; n=5 mares) or a single injection of biorelease altrenogest (n=10 cycles; n=6 mares). In all study groups, PGF2α was given 2 days before cessation of progestagen treatment. In Study 1, mares responded in six of 11 cycles (54%) where treatment occurred with normal ovarian follicular development post hormone therapy. In Study 2, mares responded in four of five (80%, oral altrenogest) and eight of 10 (80%, injectable altrenogest) cycles with the development of an ovulatory follicle. With the use of injectable altrenogest, there was an obvious suppression of urinary estrogens and progetsagens. These results indicate that manipulation of the estrous cycle of Przewalski's mares can be achieved by administering oral (12 days) or injectable form of altrenogest in conjunction with PGF2α. Findings in the present study may have long term application for the development of timed artificial insemination as a genetic management tool for this critically endangered equid.

Long-acting neuroleptic use for reproductive management of non-domestic ungulates using the domestic goat (Capra hircus) as a model.

Fluphenazine decanoate is a long-acting phenothiazine neuroleptic that attenuates the stress response and may be useful during intensive handling for reproductive procedures in non-domestic ungulates. However, phenothiazines are also associated with elevated serum prolactin, which can suppress fertility in some species. For this study, 10 female domestic goats were used as a model for non-domestic caprids to test effects of fluphenazine decanoate on serum cortisol and reproductive cyclicity following estrus synchronization. Two identical trials were conducted during the breeding season, employing a random crossover design. First, females underwent estrus synchronization using a 14-day treatment with progesterone (330 mg; CIDR). After 7 days of CIDR exposure, the treatment group (n = 5) received fluphenazine decanoate (1.0 mg/kg IM) and controls (n = 5) received an equivalent volume of 0.9% saline IM. At CIDR withdrawal (Day 14), animals received 125 mg cloprostenol sodium to lyse any luteal tissue and synchronize estrus. Blood was collected every 2 hr from 36 hr after CIDR withdrawal until 24 hr after standing estrus, or up to 5 days to monitor stress and reproductive hormones. Serum cortisol, prolactin, luteinizing hormone (LH) and progesterone concentrations were determined by enzyme immunoassay. While treatment with fluphenazine was associated with lower cortisol concentrations compared to controls (P = 0.001), 4 of the 10 treated animals experienced elevated serum prolactin, suppression of the LH surge and inhibition of ovulation. These findings suggest that long-acting neuroleptic drugs reduce the adrenal stress response, but may interfere with reproductive responses and negatively influence breeding success.

Fundamental studies of the reproductive biology of the endangered persian onager (Equus hemionus onager) result in first wild equid offspring from artificial insemination.

We studied the Persian onager (Equus hemionus onager), an endangered equid subspecies. The objective was to characterize endocrine patterns and ovarian follicular dynamics of females as well as seminal traits and sperm sensitivity to cryopreservation in males as a prerequisite to testing the feasibility of artificial insemination (AI). Urinary progesterone and estrogen metabolite profiles were determined by enzyme immunoassay in 11 females. Serial ultrasonography of ovarian activity was performed for 2 mo in a subset of four females. Females were seasonally polyestrous (June-November). Ovarian morphometry via ultrasonography and urinary progesterone profiles were more reflective of reproductive events than urinary estrogen patterns, and preovulatory follicle size was smaller than reported for other equid species. There was evidence for lactational suppression of estrus for up to 1.5 yr in nursing dams. Electroejaculation allowed recovery of highly motile sperm from 7, anesthetized males on 57% of occasions. Spermatozoa, including motility and acrosomal integrity, were resilient to freeze-thawing. Artificial insemination was successful in 2 of 3 females following detection of a dominant follicle and deslorelin administration, resulting in births of a healthy female and male foal by using fresh/chilled and frozen/thawed sperm, respectively.

Abnormal reproductive patterns in Przewalski's mares are associated with a loss in gene diversity.

The ex situ population of the Przewalski's horse (Equus ferus przewalskii) is not self-sustaining (20% foaling rate), and the demography is skewed toward aging individuals with low gene diversity. We designed the present study to gain a better understanding of the reproductive biology of the Przewalski's mare and to determine whether age and gene diversity influenced reproductive function. Urine samples were collected 3-7 days/wk from 19 mares from May to September, and ultrasound examinations of follicular structures were performed 3 days/wk for 5 wk from May through July in nine individuals. A high proportion of mares exhibited abnormal (endocrine, 5 [26.3%] of 19; follicular, 2 [22.2%] of 9) or acyclic (endocrine, 4 [21.1%] of 19; follicular, 3 [33.3%] of 9) reproductive patterns. In four cyclic mares, estrous cycle length was 25.1 ± 1.2 days, with 12.2 ± 0.9 days of diestrus. Follicles in cyclic mares grew 1.2 ± 0.6 mm per day and ovulated after reaching 40.4 ± 8.9 mm. Mares with a high coefficient of inbreeding excreted reduced levels of mean urinary estrogens (r(2) = 0.476, P < 0.05), but age had no significant impact on reproductive patterns in this population. Overall, these data suggest that long-term genetic management of this population is necessary to maintain reproductive fitness.

Analysis and cytologic characterization of hemocytes from freshwater mussels (Quadrula sp.).

BACKGROUND: Freshwater mussels are among the most endangered taxa in North America and minimally invasive techniques to evaluate their health are needed. OBJECTIVE: The objective of this study was to develop a standardized approach for identifying and enumerating the cellular components of freshwater mussel hemolymph. METHODS: Hemocyte clumping, total hemocyte count, and hemocyte morphology were compared in untreated hemolymph or hemolymph treated with formalin, sodium citrate, sodium heparin, EDTA, water, or l-cysteine. Morphology was then used to categorize hemocytes and perform a 100-cell differential. RESULTS: Treatment with formalin or >25 mg/mL l-cysteine reduced hemocyte clumping, although only formalin significantly increased the total hemocyte count. However, formalin also induced crenation that impaired hemocyte identification. Both EDTA and sodium citrate-induced hemocyte degranulation while sodium citrate and >40 mg/mL l-cysteine-induced cell lysis. Hemocytes could be categorized into 2 groups of granulocytes (eosinophilic or basophilic) and 2 groups of agranulocytes (large or small) for performing a cytologic differential. The differential was not significantly altered by anticoagulant treatments providing cell morphology was adequate for obtaining a differential. Eosinophilic granulocytes predominated (59%) with fewer large agranulocytes (27%) and basophilic granulocytes (13%). Small agranulocytes comprised 2% of the total population. CONCLUSIONS: No single treatment provided an optimal method to evaluate freshwater mussel hemolymph. Maximal hemocyte counts were obtained following formalin treatment. l-cysteine reduced clumping and maintained hemocyte morphology for performing a cytologic differential. These techniques provide a standardized approach for the hematologic evaluation of freshwater mussels.

Clinical Parelaphostrongylus tenuis infection in two captive American bison (Bison bison).

CASE DESCRIPTION: 2 juvenile (17 and 19 months of age) male American bison (Bison bison) were examined because of acute bilateral hind limb weakness and ataxia; 1 animal also had urinary incontinence. TREATMENT AND OUTCOME: Given the clinical signs and rapid deterioration in the condition of these 2 animals, obtaining a definitive diagnosis was considered essential to minimizing the risk of disease in the remaining bison herd and among other animals at the facility. Therefore, both affected animals were euthanized. At necropsy, no gross abnormalities were seen. Histologic examination of sections of the brains from both animals revealed mild to moderate multifocal aggregates of eosinophils and mononuclear cells in perivascular regions of the meninges and gray matter of the cerebrum, cerebellum, and brainstem. Systematic examination of multiple sections of brain and spinal cord revealed evidence of nematode sections and aberrant parasite migration. CLINICAL RELEVANCE: Findings suggested that CNS migration of Parelaphostrongylus tenuis in American bison may cause clinical signs. These findings have implications for the management of captive bison and free-ranging bison sharing ranges with white-tailed deer (Odocoileus virginianus), the definitive host, and elk (Cervus elaphus canadensis).