Clinical Theriogenology

Effects of fatty acid binding protein in the maturation media of bovine oocytes on in vitro embryo development

Jessica Looman, Sydney Hickerson, John Gibbons — Thu, 07 May 2026 10:59:18 +0000

Oocytes matured in vitro have higher lipid content and fatty acid binding protein3 (FABP3) may mediate the inter or intracellular transport of lipids and fatty acids. Our aim was to investigate the effects of varying concentrations of FABP3 during in vitro maturation on blastocyst development of oocytes. In Experiment 1, oocytes from abattoir-derived ovaries were matured in media supplemented with 1, 10 or 20 or 0 μg/ml FABP3 (control). In Experiments 2 and 3, oocytes collected via transvaginal aspiration from mature nonlactating Jersey cows (425-500 kg) were matured in media at concentrations with 10 or 20 and 0 μg/ml FABP3 (control; Experiment 2), 1 or 5 and 0 μg/ml, FABP3 (control; Experiment 3). After fertilization and 8 days of culture, cleavage and blastocyst rates were analysed. In Experiment 1, cleavage rate was higher (p < 0.05) in 20 μg/ml group compared to control and 10 μg/ml FABP3 groups. In Experiment 2, cleavage rate was higher (p < 0.05) in control and 10 μg/ml groups compared to 20 μg/ml group and blastocyst development was higher (p < 0.05) in control compared to 20 μg/ml group. In Experiment 3, cleavage and blastocyst development was higher (p < 0.05) in the control group compared to 5 μg/ml group. There was no clear benefit of FABP3 demonstrated among tested concentrations; however, 20 μg/ml during in vitro maturation appeared to be detrimental to cleavage and embryo development in oocytes aspirated from live cows.

Prostaglandin pretreatment enhances ova recovery in cattle

Jessica Looman, Luis Ochoa, Sydney Hickerson, John Gibbons — Thu, 07 May 2026 10:36:19 +0000

Despite ovarian superstimulation (superovulation) advantages in cattle over the last 40 years, fewer ova or embryos are recovered after uterine lavage than the number of corpora lutea (CL) on the ovaries. Uterine contraction agents given before collection may address this issue. We evaluated the effects of prostaglandin F_2α (PGF_2α) treatment prior to embryo collection using a novel approach which allowed embryo donors to serve as their own control. After follicular wave synchronization and follicle stimulating hormone (FSH) treatment, embryos were collected from a uterine horn (control) and cows were given intramuscular PGF_2α (25 mg in Experiments 1 and 3, 6.25 mg in Experiment 2) prior to collection from the second uterine horn. Ova and embryos were collected 5 minutes after PGF_2α in Experiments 1 and 2, and after 1 hour in Experiment 3. Although the number of CL were similar, ova recovery rates were higher (p < 0.05) from the uterine horn collected after treatment.

Cholesterol protects stallion sperm from cold shock but egg yolk is necessary for optimal cryopreservation

Marta Cittone, Patricio Razquin, James Graham — Tue, 07 Apr 2026 00:00:00 +0000

Membrane cholesterol affects sperm membrane fluidity and stability at low temperatures. Sperm from species with high cholesterol:phospholipid ratios (human and rabbit) are resistant to cooling damage whereas equine sperm with low cholesterol:phospholipid ratios (~ 0.3) are sensitive to cooling and freezing damage. Cholesterol-loaded cyclodextrins (CLC) improve sperm cryosurvival; however, cholesterol-treated sperm have always been diluted with egg yolk or milk-based cryopreservation media that also protect sperm from cooling damage. Therefore, cholesterol’s effect on mitigating cooling or freezing damage remains unclear. We examined how CLC affect stallion sperm membrane cholesterol composition and whether cholesterol alone can mitigate cold shock and cryopreservation damage. Stallion sperm treated with CLC (0-1.8 mg) were subjected to cold shock (0°C) or cryopreservation, with or without egg yolk, using 1 or 2 step cryopreservation protocols; CLC increased sperm cholesterol:phospholipid ratios 2.7 fold. After cold shock, sperm motility was lower (p < 0.05) in control (8%) than CLC-treated sperm (39-65%), and CLC maintained high motility in cold shocked sperm, similar to fresh sperm. Sperm motility was similar for sperm cryopreserved in medium with egg yolk in either 1 or 2 step cryopreservation protocols. Although CLC alone provided modest cryopreservation protection, the combination of CLC and egg yolk resulted in greater motility and viability (p < 0.05) than either CLC or egg yolk alone. Furthermore, the cholesterol:phospholipid ratio that protected sperm from cold shock damage varied widely among stallions (0.33-0.79). In conclusion, adding cholesterol to sperm membrane eliminated cold shock damage but egg yolk provided additional cryoprotection, particularly at low CLC concentrations.

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.

Neurologic dysfunction in newborn calves: understanding neonatal encephalopathy in clinical practice

Bailey Bailey, Ramanathan Kasimanickam — Tue, 07 Apr 2026 00:00:00 +0000

Neonatal encephalopathy (NE), a clinically important syndrome causing neurologic dysfunction in newborn calves, contributes to early-life morbidity and mortality. Affected calves exhibit impaired adaptation to extrauterine life, including delayed or absent respiration, difficulty standing, and ineffective nursing, compromising colostrum intake, passive immunity transfer, and overall viability. NE reflects a clinical presentation rather than a specific etiologic diagnosis and may result from hypoxic-ischemic injury, metabolic disturbances, trauma, infection, or intoxication. Historical terms such as ‘dummy calf’ and weak calf syndrome lack diagnostic precision and should be interpreted cautiously. Neonatal maladjustment syndrome, derived largely from equine and human literature, represents a proposed mechanistic subset of NE, potentially involving persistent neurosteroid activity but remains speculative in calves. Emerging hypotheses, including neurosteroid persistence and maternal gut microbiome influences, may contribute to neonatal maladaptation but require further validation. Management is primarily supportive whereas prevention should focus on dystocia reduction, timely obstetric intervention, and optimized periparturient and early neonatal care. Clarifying terminology and understanding underlying mechanisms is essential to improve clinical decision-making and research interpretation.

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).

Toxicoinfectious metritis with fatal complications following retained fetal membranes in a mare

Wed, 22 Apr 2026 11:51:27 +0000

A 7-year, American Paint maiden mare, was presented 2 days after foaling following manual removal of retained fetal membranes. Fetid vaginal discharge was noticed and subinvoluted uterus was palpated transrectally. Endometrial cytology had Gram-positive cocci, Gram-negative and positive rods, and clostridial organisms with spores. Small fragment of fetal membranes was retrieved during uterine lavage. Mare developed signs of gastrointestinal disease with a large colon impaction and had refractory pain (response to multimodal analgesia). Despite intensive therapy, mare’s condition deteriorated. Abdominocentesis revealed turbid fluid with increased protein and lactate consistent with elevated inflammatory cells and peritonitis. Necropsy confirmed necrotizing metritis with vascular thrombosis, localized fibrinous peritonitis, and focal adhesion between uterus and pelvic flexure of the large intestine. This case illustrated the rapid progression from retained fetal membranes to systemic illness and highlighted the diagnostic value of cytology to select antimicrobial agents in advance of culture and sensitivity results.

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.