Clinical Theriogenology

Intrinsic and management-related factors associated with bull breeding soundness examination failure: a retrospective study

Chika Okafor, Lew Strickland, Brian Whitlock — Wed, 11 Mar 2026 05:50:01 +0000

Bull breeding soundness examination (BBSE) is critical for identifying subfertile bulls and preventing reproductive and economic losses in cow/calf systems. This retrospective study evaluated intrinsic and extrinsic factors associated with BBSE failure in bulls. Data from 1,375 BBSE records (2008-2018) included age, breed, body condition, scrotal circumference (SC), semen quality traits, physical and reproductive findings, examining veterinarian, season, and prior BBSE history. Outcomes were classified as pass or fail. Among failures, sperm morphologic abnormalities were the predominant reason (73.3%), followed by inadequate SC (8.6%), penile abnormalities (5.5%), no ejaculate produced (4.6%), and lameness (3.1%). Bulls that previously failed BBSE were likely to fail again (> 6 times) with abnormal morphology accounting for 93% of repeat failures. Significant intrinsic predictors of failure included SC, sperm morphology, progressive motility, primary and secondary defects, gross motility, breed, and body condition score. Significant extrinsic predictors included examining veterinarian, year, quarter, and prior BBSE status. A significant downward trend (p = 0.0299) in failure prevalence was observed. In the multivariable model, previous BBSE, year of examination, and examination quarter remained independently associated with failure. Results highlighted the multifactorial nature of BBSE outcomes and emphasized the importance of considering prior evaluation history, seasonal timing, and persistent morphology abnormalities when interpreting results and managing herd reproductive performance.

Reproductive hormones, antral follicle count, and transvaginal oocyte aspiration outcomes in mares receiving intravenous clomiphene citrate

Thu, 22 Jan 2026 14:10:59 +0000

The likelihood of creating an in vitro produced foal is much lower in horses than in other species because of inefficient in vitro embryo production. Inability to superstimulate ovaries is a major factor that could be addressed by choosing a right compound; clomiphene citrate (CC), a selective estrogen receptor modulator, is a potential agent. Therefore, 2 experiments were performed; mares received 2,000 mg of intravenous CC, every 24 hours for 5 days to assess the effects on reproductive hormone concentrations, uterine and ovarian responses, and oocyte parameters. In Experiment 1, 6 mares received CC and were monitored for plasma CC concentrations, serum reproductive hormone concentrations, and ovarian responses. Transvaginal oocyte aspirations were performed and in vitro embryo production parameters were collected. In Experiment 2, 6 mares received CC; reproductive hormone concentrations and ovarian responses were compared to control group (n = 6). Concentrations of CC had positive correlations with antral follicle count and uterine edema (r = 0.60, p = 0.0004 and r = 0.47, p = 0.009, respectively), and a moderate negative correlation with follicle-stimulating hormone (r = – 0.48, p = 0.001). Compared to controls, there were no differences in reproductive hormone concentrations, ovarian responses, or oocytes recovered in mares receiving CC; average blastocyst rate of matured oocytes was 47.5% in treated mares.

Common periparturient complications in female dogs

Sarah Ward, Patricio Razquin, Greg Burns, Jenny Sones — Fri, 23 Jan 2026 08:08:38 +0000

In female dog’s reproduction, periparturient period is a critical time, often characterized by morbidity/mortality of the dam and fetus/neonates. Preexisting risk factors influencing dam’s postpartum survival include body condition, nutritional status, and endocrinopathies. Periparturient complications in the dog are common and require knowledgeable observation to detect, diagnose, and treat. Focus of this review is to describe the clinical manifestations of infectious (mastitis and metritis) and noninfectious (ketosis and eclampsia) periparturient disorders that require supportive and interventional management; to present diagnostic approach from a practical perspective along with treatment protocols from literature; and to enable readers to understand the pathophysiology of these conditions, clinical signs, diagnostics, treatments, and prevention.

Ovarian follicular dynamics in cattle: a comprehensive review

Tue, 20 Jan 2026 00:00:00 +0000

Ovarian follicular dynamics in cows is characterized by well-coordinated development and maturation of ovarian follicles. In the bovine ovary, follicles advance from primordial stages (present at birth), to primary, secondary, and tertiary stages. During puberty, there is a marked increase in pulsatile secretion of gonadotropin-releasing hormone from the hypothalamus; this stimulates the anterior pituitary to release follicle stimulating hormone and luteinizing hormone, promoting follicle growth and selection with some dominant follicles ovulating. Estradiol 17-β from these developing follicles regulates the reproductive cycle, promoting estrus and cyclicity. Understanding these dynamics is vital for optimizing reproductive management and enhancing fertility. This review describes ovarian follicular dynamics and puberty in cattle.

Evaluating sperm fertilizing potential: what can we predict?

Raul Gonzalez-Castro — Fri, 16 Jan 2026 06:04:39 +0000

Multiparametric approaches that characterize the functional and metabolic aspects of sperm offer real-time information to discriminate and identify sperm subpopulations with attributes suitable for fertilization. In vivo, sperm requires various abilities to fertilize an oocyte that are less relevant for in vitro fertilization (IVF). Traditional evaluations such as sperm motility, DNA integrity, morphology, and viability as a measure of plasma membrane integrity are less sensitive and specific in detecting sublethal damage that can reduce a sample’s fertilizing potential. During in vivo fertilization, the female reproductive tract has a critical role in removing most of the dead sperm and those with sublethal damage that may explain why certain sperm variables have reduced predictive power for IVF success. Assessment of metabolic and physiological status provides new methods to estimate sperm fertilizing potential both in vivo and in vitro by identifying sublethal damage and capacitation-related changes. For IVF and intracytoplasmic sperm injections, sperm factors involved in oocyte activation and embryo development (e.g. phospholipase C zeta 1 [PLCZ1]), are considered the major male factors contributing to the failure of oocyte activation and embryo development. Reduced amounts, abnormal localization, and genetic variability of the PLCZ1 have been identified as factors in male infertility, suggesting potential diagnostic and prognostic value for clinical applications. However, male reproductive performance and fertilization are highly complex processes influenced by several factors. This complexity limits the predictive value of any single sperm assessment for reliably determining fertility outcomes.

The future of theriogenology: advancing research, clinical innovation, and education

Ramanathan Kasimanickam, Divakar Ambrose, John Kastelic, Richard Hopper — Wed, 14 Jan 2026 00:00:00 +0000

Theriogenology, the veterinary discipline focused on animal reproduction, is undergoing rapid transformation, driven by innovations in biotechnology, artificial intelligence and global health integration. This review explores the future of theriogenology through 4 key dimensions: research, teaching, outreach, and ethics. In research, cutting-edge technologies (e.g. clustered regularly interspaced short palindromic repeats, gene editing, multiomics, and artificial intelligence-enhanced diagnostics) are reshaping fertility management, reproductive efficiency and species conservation. In education, immersive simulations, hybrid learning models and interdisciplinary curricula, are preparing future practitioners with technical skills and ethical frameworks needed for modern clinical and research environments. Outreach efforts are expanding the field’s impact, bringing reproductive technologies to underserved communities, supporting wildlife conservation, and contributing to ‘One Health’ initiatives. However, these advancements raise complex ethical and regulatory challenges, including concerns regarding genetic modification, equitable access and cross-border collaboration. Addressing these issues will require global cooperation, capacity-building and a commitment to responsible innovation. Theriogenology’s future lies not only in scientific progress but also in its ability to bridge disciplines and communities for the benefit of animals, ecosystems and society at large.

Bovine uterine torsion: current insights and clinical perspectives

Pururava Sharma, Akshay Sharma, Dawa Yangka, Pravesh Kumar — Wed, 07 Jan 2026 08:39:40 +0000

Bovine uterine torsion is an obstetrical emergency that affects dairy cattle and buffaloes and contributes substantially to maternal and fetal mortality. Gravid uterus rotates on its longitudinal axis (often > 180°) during the late first stage of parturition or early second stage; however, pre or postpartum occurrence is also possible. Etiopathogenesis is multifactorial, involving maternal anatomical predispositions (e.g. short and ventrolateral attachment of broad ligaments, multiparity, and environmental factors), whereas fetal characteristics include weight, position, and movement. Clinical diagnosis involves transrectal and vaginal examination; recent advances in ultrasonography and Doppler imaging (visualization of placental perfusion, uterine wall integrity, and fetal viability) have enhanced diagnostic accuracy. Severe torsion compromises uterine vascularity, resulting in ischemia, degeneration, and fetal death if untreated. Histopathological evaluations have revealed substantial alterations including necrosis, adhesion formation, reduced placental expression of estrogen receptors and vascular endothelial growth factor. Clinical management includes rolling techniques (modified Schaffer’s method) for early or mild torsion and laparotomy or cesarian surgery for advanced cases. Prognosis depends on the degree and duration of torsion and the presence of complications (e.g. adhesions or endotoxemia).

Pregnancy hydrops in a recipient mare carrying an in vitro-produced embryo

Mariah Slack, Maria Schnobrich, Rachel Doenges, Peter Morresey — Thu, 22 Jan 2026 14:33:59 +0000

An 8-year, Thoroughbred mare, was referred on day 225 of pregnancy for progressive abdominal distension and on owner’s suspicion of hydrops. Mare was a recipient of a vitrified and warmed embryo that was produced via intracytoplasmic sperm injection. Transabdominal ultrasonography revealed increased allantoic and amniotic fluid depths. Fetal urachus was distended and fetal mouth was open throughout the examination. To salvage the mare, termination of pregnancy was elected on day 230 of pregnancy due to progressive abdominal distension and evidence of fetal compromise. Gross examination of the fetus revealed craniofacial abnormalities that precluded the mouth from closing. This case is another example of fetal craniofacial malformations’ association with hydrops; it is also important to consider the potential association of hydrops with advanced reproductive techniques, as observed in cattle following in vitro fertilization and cloning.

Bilateral uterine horn segmental aplasia in a doe

Adriana Garzon, Tessa Kell, Bret R. McNabb, Kevin Keel, Fauna Smith — Thu, 22 Jan 2026 14:53:46 +0000

This case documents a rare reproductive abnormality in a doe that resulted in infertility. Multiple fluid-filled portions of the uterine horns were identified via transabdominal ultrasonography; doe was unresponsive to prostaglandin F_2α treatment. Following euthanasia, postmortem examination confirmed multifocal bilateral segmental uterine horn aplasia with hydrometra and hydrosalpinx. This case represents a novel combination of antemortem clinical diagnosis with postmortem confirmation of uterine segmental aplasia, involving uterine horns and oviducts.