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Animal health and veterinary medicine are integral to One Health, contributing important perspectives on complex challenges arising at the human-animal-environment interface. The published Competency-Based Veterinary Education (CBVE) framework dedicates a domain of competence and three associated sub-competencies to public health (Domain 4). However, a panel of One Health scientists sought to establish additional outcomes believed necessary to support core veterinary curricula related to veterinary public health (VPH)/One Health. We hypothesized that early career veterinarians use knowledge, skills, and abilities consistent with VPH/One Health and that the existing CBVE could incorporate these concepts. We conducted key informant and exploratory interviews with veterinarians across 12 sectors of veterinary medicine and used inductive coding to identify VPH/One Health codes. We then cross-analyzed these codes with the existing CBVE framework to incorporate field-validated VPH/One Health codes into the published framework. Thirty codes emerged which were designated as either adequately represented (5), not represented (6), or represented with sub-competency creation or augmentation recommended (19) in the existing framework. This information was used to cross-map, validate, and update the CBVE sub-competencies so that they accurately reflect the breadth and depth of One Health engagement required for competent veterinarians. This iterative, evidence-based revision process is a model for integrating One Health into medical professional curricula.

One Health is a collaborative approach that requires synergies between human, animal and environmental health sectors, other key sectors, and partners supporting these capacity-building efforts. Multiple One Health capacity-building tools are available that can be used independently or together. Two tools that have been used in sequence to inform each other include the US Centers for Disease Control and Prevention's One Health Zoonotic Disease Prioritization (OHZDP) Process and University of Minnesota/US Department of Agriculture's One Health Systems Mapping and Analysis Resource Toolkit™ (OH-SMART). In August 2017, a workshop was held in Islamabad, Pakistan, that integrated these two tools for the first time. In this integrated workshop, we used the OHZDP to develop a list of priority zoonotic diseases for Pakistan and OH-SMART™ to conduct a partner assessment and disease-specific gap analysis. Both tools were used to identify areas for One Health collaboration for the priority zoonotic diseases. Additionally, we trained 11 in-country facilitators representing the human and animal health sectors on both tools. This manuscript describes the integration of these two tools-using the Pakistan workshop as a process case study-to inform future efforts to implement One Health tools synergistically. Implementation of the technical and logistical aspects of the integrated workshop was detailed: (1) workshop preparation, (2) facilitator training, (3) workshop implementation and (4) workshop outcomes. Sixteen months after the workshop, we conducted an in-country facilitator survey to follow-up on the utility of both tools and the training for facilitators. We evaluated facilitator survey results using a qualitative analysis software Atlas.ti. Using the OHZDP Process and OH-SMART™ together achieved continuity between the two processes and provided a professional development opportunity for in-country facilitators. Based on the success of this integrated workshop, partners developing and implementing One Health tools should recognize the importance of collaboration to maximize outcomes., (© 2022 The Authors. Zoonoses and Public Health published by Wiley-VCH GmbH. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Background: The level of preparedness of the health care workers, the health facility and the entire health system determines the magnitude of the impact of an Ebola Virus Disease (EVD) outbreak as demonstrated by the West African Ebola outbreak. The objective of the study was to assess preparedness of the health care facilities and identify appropriate preparedness measures for Ebola outbreak response in Kasese and Rubirizi districts in western Uganda., Methods: A cross sectional descriptive study was conducted by interviewing 189 health care workers using a structured questionnaire and visits to 22 health facilities to determine the level of health care system preparedness to EVD outbreak. District level infrastructure capabilities, existence of health facility logistics and supplies, and health care workers' knowledge of EVD was assessed. EVD Preparedness was assessed on infrastructure and logistical capabilities and the level of knowledge of an individual health work about the etiology, control and prevention of EVD., Results: Twelve out of the 22 of the health facilities, especially health center III's and IV's, did not have a line budget to respond to EVD when there was a threat of EVD in a nearby country. The majority (n = 13) of the facilities did not have the following: case definition books, rapid response teams and/or committees, burial teams, and simulation drills. There were no personal protective equipment that could be used within 8 h in case of an EVD outbreak in fourteen of the 22 health facilities. All facilities did not have Viral Hemorrhagic Fever (VHF) incident management centers, isolation units, guidelines for burial, and one-meter distance between a health care worker and a patient during triage. Overall, 54% (n = 102) of health care workers (HCWs) did not know the incubation period of EVD. HCWs who had tertiary education (aOR = 5.79; CI = 1.79-18.70; p = 0.003), and were Christian (aOR = 10.47; CI = 1.94-56.4; p = 0.006) were more likely to know about the biology, incubation period, causes and prevention of EVD., Conclusions: Feedback on the level of preparedness for the rural districts helps inform strategies for building capacity of these health centers in terms of infrastructure, logistics and improving knowledge of health care workers.

Zoonotic diseases pose a significant health challenge at the human-wildlife interface, especially in Sub-Saharan Africa where ecosystem services contribute significantly to local livelihoods and individual well-being. In Uganda, the fragmented forests of Hoima district, form part of a "biodiversity and emerging infectious disease hotspot" composed of communities with high dependency on these wildlife protected areas, unaware of the associated health risks. We conducted a cross-sectional mixed methods study from March to May 2017 and interviewed 370 respondents, using a semi-structured questionnaire from eight villages neighbouring forest fragments in Hoima District, Uganda. Additionally, a total of ten (10) focus group discussions (FGDs) consisting of 6-10 men or women were conducted to further explore the drivers of hunting and perception of zoonotic disease risks at community level. Qualitative and quantitative data were analysed using content analysis and STATA version 12 respectively. We found twenty-nine percent (29.0%, CI: 24.4-33.9) of respondents were engaged in hunting of wildlife such as chimpanzee (Pan troglodytes) and 45.8% (CI: 40.6-51.0), cane rats (Thryonomyidae spp). Acquisition of animal protein was among the main reasons why communities hunt (55.3%, CI: 50.1-60.4), followed by "cultural" and "medicinal" uses of wildlife and or its parts (22.7%, CI: 18.6-27.4). Results further revealed that hunting and bushmeat consumption is persistent for other perceived reasons like; bushmeat strengthens the body, helps mothers recover faster after delivery, boosts one's immunity and hunting is exercise for the body. However, respondents reported falling sick after consumption of bushmeat at least once (7.9%, CI: 5.3-11.1), with 5.3% (CI: 2.60-9.60) reporting similar symptoms among some family members. Generally, few respondents (37.0%, CI: 32.1-42.2) were aware of diseases transmissible from wildlife to humans, although 88.7% (CI: 85.0-92.0) had heard of Ebola or Marburg without context. Hunting non-human primate poses a health risk compared to edible rats (cane rats) and wild ruminants (cOR = 0.4, 95% CI = 0.1-0.9) and (cOR = 0.7, 95% CI = 0.2-2.1) respectively. Study suggests some of the pathways for zoonotic disease spillover to humans exist at interface areas driven by livelihoods, nutrition and cultural needs. This study offers opportunities for a comprehensive risk communication and health education strategy for communities living at the interface of wildlife and human interactions., Competing Interests: The authors have declared that no competing interests exist.

Bacillus anthracis, the bacteria that causes anthrax, a disease that primarily affects herbivorous animals, is a soil borne endospore-forming microbe. Environmental distribution of viable spores determines risky landscapes for herbivore exposure and subsequent anthrax outbreaks. Spore survival and longevity depends on suitable conditions in its environment. Anthrax is endemic in Queen Elizabeth Protected Area in western Uganda. Periodic historical outbreaks with significant wildlife losses date to 1950s, but B. anthracis ecological niche in the ecosystem is poorly understood. This study used the Maximum Entropy modeling algorithm method to predict suitable niche and environmental conditions that may support anthrax distribution and spore survival. Model inputs comprised 471 presence-only anthrax occurrence data from park management records of 1956-2010, and 11 predictor variables derived from the World Climatic and Africa Soil Grids online resources, selected considering the ecology of anthrax. The findings revealed predicted suitable niche favoring survival and distribution of anthrax spores as a narrow-restricted corridor within the study area, defined by hot-dry climatic conditions with alkaline soils rich in potassium and calcium. A mean test AUC of 0.94 and predicted probability of 0.93 for anthrax presence were registered. The five most important predictor variables that accounted for 93.8% of model variability were annual precipitation (70.1%), exchangeable potassium (12.6%), annual mean temperature (4.3%), soil pH (3.7%) and calcium (3.1%). The predicted suitable soil properties likely originate from existing sedimentary calcareous gypsum rocks. This has implications for long-term presence of B. anthracis spores and might explain the long history of anthrax experienced in the area. However, occurrence of suitable niche as a restricted hot zone offers opportunities for targeted anthrax surveillance, response and establishment of monitoring strategies in QEPA., Competing Interests: The authors declare having no competing interests.

Advocates for a One Health approach recognize that global health challenges require multidisciplinary collaborative efforts. While past publications have looked at interdisciplinary competency training for collaboration, few have identified the factors and conditions that enable operational One Health. Through a scoping review of the literature, a multidisciplinary team of researchers analyzed peer-reviewed publications describing multisectoral collaborations around infectious disease-related health events. The review identified 12 factors that support successful One Health collaborations and a coordinated response to health events across three levels: two individual factors (education & training and prior experience & existing relationships), four organizational factors (organizational structures, culture, human resources and, communication), and six network factors (network structures, relationships, leadership, management, available & accessible resources, political environment). The researchers also identified the stage of collaboration during which these factors were most critical, further organizing into starting condition or process-based factors. The research found that publications on multisectoral collaboration for health events do not uniformly report on successes or challenges of collaboration and rarely identify outputs or outcomes of the collaborative process. This paper proposes a common language and framework to enable more uniform reporting, implementation, and evaluation of future One Health collaborations., Competing Interests: The authors have declared that no competing interests exist.

The capacity to effectively and efficiently address threats to public and animal health requires an adequately trained workforce. A prerequisite for this is an effective plan for building the capacity of both private and public health workers. Yet capacity building and workforce development within One Health collaboration remain challenging for a number of reasons, including competing priorities, sectorspecific funding and a lack of trust and communication across sectors. Practical considerations, such as differences in language and culture, and working across time zones and geography, also have a considerable influence. Consequently, previous attempts to build capacity have traditionally lacked the attributes necessary for effective development and sustainability, such as continuity and systematic coordination of the learning process. Through the presentation and analysis of two recently implemented workforce development programmes, the authors highlight effective characteristics of workforce initiatives to build capacity. Such programmes can play a strategic role in developing, coordinating and supporting systematic and sustainable training for One Health and Veterinary Services performance on a regional and global scale., (© World Organisation for Animal Health (OIE), 2019)

Background: Anthrax is a zoonotic disease primarily of herbivores, caused by Bacillus anthracis, a bacterium with diverse geographical and global distribution. Globally, livestock outbreaks have declined but in Africa significant outbreaks continue to occur with most countries still categorized as enzootic, hyper endemic or sporadic. Uganda experiences sporadic human and livestock cases. Severe large-scale outbreaks occur periodically in hippos (Hippopotamus amphibious) at Queen Elizabeth Protected Area, where in 2004/2005 and 2010 anthrax killed 437 hippos. Ecological drivers of these outbreaks and potential of hippos to maintain anthrax in the ecosystem remain unknown. This study aimed to describe spatio-temporal patterns of anthrax among hippos; examine significant trends associated with case distributions; and generate hypotheses for investigation of ecological drivers of anthrax., Methods: Spatio-temporal patterns of 317 hippo cases in 2004/5 and 137 in 2010 were analyzed. QGIS was used to examine case distributions; Spearman's nonparametric tests to determine correlations between cases and at-risk hippo populations; permutation models of the spatial scan statistics to examine spatio-temporal clustering of cases; directional tests to determine directionality in epidemic movements; and standard epidemic curves to determine patterns of epidemic propagation., Key Findings: Results showed hippopotamus cases extensively distributed along water shorelines with strong positive correlations (p<0.01) between cases and at-risk populations. Significant (p<0.001) spatio-temporal clustering of cases occurred throughout the epidemics, pointing towards a defined source. Significant directional epidemic spread was detected along water flow gradient (206.6°) in 2004/5 and against flow gradient (20.4°) in 2010. Temporal distributions showed clustered pulsed epidemic waves., Conclusion: These findings suggest mixed point-source propagated pattern of epidemic spread amongst hippos and points to likelihood of indirect spread of anthrax spores between hippos mediated by their social behaviour, forces of water flow, and persistent presence of infectious carcasses amidst schools. This information sheds light on the epidemiology of anthrax in highly social wildlife, can help drive insight into disease control, wildlife conservation, and tourism management, but highlights the need for analytical and longitudinal studies aimed at clarifying the hypotheses., Competing Interests: The authors have declared that no competing interests exist.

A One Health approach is critical to strengthening health security at country, regional, and global levels. However, operationally its uptake remains limited. Recent momentum in assessing capacity to effectively prevent, detect, and respond to disease threats has resulted in identification of gaps that require dedicated action. This article highlights relevant tools, standards, and guidance to assist countries and institutions in meeting the collective vision articulated at the 2018 Prince Mahidol Award Conference on "Making the World Safe from the Threats of Emerging Infectious Diseases." Taking stock of assessment findings, resources, priorities, and implementation initiatives across human and animal health, environment and disaster risk reduction sectors can help expand participation in global health security, target risk drivers, and form synergies for collective action and shared gains for both emerging and endemic disease challenges. In addition to health security gains, a multisectoral, One Health approach can drive benefits for wider health sector and global development goals.

Background: Africa of late has been faced with challenges that require a multidisciplinary and multisectoral approach to address them, and academic and non-academic institutions have played a key role in training and conducting research that would promote the One Health approach., Objectives: The objective of this review was to document networks and organizations conducting One Health training, research, and outreach in Africa, as one of a series of articles around the world., Methods: Data for this review were collected from organizations through key contacts of the authors and their knowledge of networks they have worked with. Web searches were conducted using One Health, training, and research as key words for work done in Africa., Results: Africa has major networks involved in One Health training, research, and outreach, with participation of both academic and non-academic institutions. This review highlights an effort in Africa to form networks to conduct multidisciplinary training and research. The main networks include Afrique One, Southern African Centre for Infectious Disease Surveillance (SACIDS), and One Health Central and Eastern Africa (OHCEA)., Conclusions: Both academic and non-academic institutions and organizations have shown an interest to conduct multidisciplinary training and research in Africa for managing challenges that Africa is facing currently, especially the outbreak of infectious diseases., Competing Interests: and funding The authors have not received any funding or benefits from industry or elsewhere to conduct this study.

Infectious diseases, in particular canine distemper virus (CDV), are an important threat to the viability of wild carnivore populations. CDV is thought to be transmitted by direct contact between individuals; therefore, the study of species interactions plays a pivotal role in understanding CDV transmission dynamics. However, CDV often appears to move between populations that are ecologically isolated, possibly through bridge hosts that interact with both species. This study investigated how an introduced species could alter multihost interactions and act as a bridge host in a novel carnivore assemblage of domestic dogs (Canis familiaris), invasive American mink (Neovison vison), and threatened river otters (Lontra provocax) in southern Chile. We found that rural dogs interact with mink near farms whereas in riparian habitats, minks and river otters shared the same latrines with both species visiting sites frequently within time intervals well within CDV environmental persistence. No interactions were observed between dogs and otters at either location. Both dog and mink populations were serologically positive for CDV, making the pathogen transfer risk to otters a conservation concern. Altogether, introduced mink in this ecosystem have the potential to act as bridge hosts between domestic dogs and endangered carnivores.

Although domestic dogs play many important roles in rural households, they can also be an important threat to the conservation of wild vertebrates due to predation, competition and transmission of infectious diseases. An increasing number of studies have addressed the impact of dogs on wildlife but have tended to ignore the motivations and attitudes of the humans who keep these dogs and how the function of dogs might influence dog-wildlife interactions. To determine whether the function of domestic dogs in rural communities influences their interactions with wildlife, we conducted surveys in rural areas surrounding protected lands in the Valdivian Temperate Forests of Chile. Sixty percent of farm animal owners reported the use of dogs as one of the primary means of protecting livestock from predators. The probability of dog-wild carnivore interactions was significantly associated with the raising of poultry. In contrast, dog-wild prey interactions were not associated with livestock presence but had a significant association with poor quality diet as observed in previous studies. Dog owners reported that they actively encouraged the dogs to chase off predators, accounting for 25-75% of the dog-wild carnivore interactions observed, depending on the predator species. Humans controlled the dog population by killing pups and unwanted individuals resulting in few additions to the dog population through breeding; the importation of predominantly male dogs from urban areas resulted in a sex ratios highly dominated by males. These results indicate that dog interactions with wildlife are related to the role of the dog in the household and are directly influenced by their owners. To avoid conflict with local communities in conservation areas, it is important to develop strategies for managing dogs that balance conservation needs with the roles that dogs play in these rural households.

Old World frugivorous bats have been identified as natural hosts for emerging zoonotic viruses of significant public health concern, including henipaviruses (Nipah and Hendra virus), Ebola virus, and Marburg virus. Epidemiological studies of these viruses in bats often utilize serology to describe viral dynamics, with particular attention paid to juveniles, whose birth increases the overall susceptibility of the population to a viral outbreak once maternal immunity wanes. However, little is understood about bat immunology, including the duration of maternal antibodies in neonates. Understanding duration of maternally derived immunity is critical for characterizing viral dynamics in bat populations, which may help assess the risk of spillover to humans. We conducted two separate studies of pregnant Pteropus bat species and their offspring to measure the half-life and duration of antibodies to 1) canine distemper virus antigen in vaccinated captive Pteropus hypomelanus; and 2) Hendra virus in wild-caught, naturally infected Pteropus alecto. Both of these pteropid bat species are known reservoirs for henipaviruses. We found that in both species, antibodies were transferred from dam to pup. In P. hypomelanus pups, titers against CDV waned over a mean period of 228.6 days (95% CI: 185.4-271.8) and had a mean terminal phase half-life of 96.0 days (CI 95%: 30.7-299.7). In P. alecto pups, antibodies waned over 255.13 days (95% CI: 221.0-289.3) and had a mean terminal phase half-life of 52.24 days (CI 95%: 33.76-80.83). Each species showed a duration of transferred maternal immunity of between 7.5 and 8.5 months, which was longer than has been previously estimated. These data will allow for more accurate interpretation of age-related Henipavirus serological data collected from wild pteropid bats.

There is little information on the reproductive biology of the male Baird's tapir (Tapirus bairdii). In this study, we characterized the ejaculate traits and evaluated the efficacy of 2 cryodiluents on sperm cryosurvival. Ejaculates were assessed for volume, pH, sperm motility, forward progression, osmolality, sperm concentration, sperm morphology, and acrosomal integrity. For cryopreservation, ejaculates with >50% total sperm motility were washed, and sperm pellets were resuspended in either Botu-Crio (CryoVital, Grandau, Germany) or INRA 96 containing 2% egg yolk and 2.5% each of methyl- and dimethylformamide (INRA 96), and they were cryopreserved over liquid nitrogen vapor. Thawed samples were incubated in vitro (25 °C) and evaluated for percent total sperm motility, forward progression, and acrosomal integrity at hourly intervals for 4 hours. Spermic ejaculates were obtained from all males, and the mean seminal volume, sperm concentration per milliliter, percent sperm motility, progressive status, and percent morphologically normal cells were 20.4 ± 4.3 mL, 101.2 ± 24.0 × 10(6)/mL, 46.1% ± 5.0%, 2.9 ± 0.1, and 6.9% ± 1.4%, respectively. There was a positive significant correlation between percent normal sperm and animal age (r = 0.66; P < .004). Cryopreservation in either Botu-Crio or INRA 96 resulted in a decline (P < .05) in percent sperm motility and acrosomal integrity. Sperm forward progression remained unaffected immediately after thawing in INRA 96 but continued to decline over time. These results characterize, for the first time, the ejaculate traits of the tapir; demonstrate that tapir spermatozoa can be cryopreserved in diluents containing amides alone or in combination with glycerol; and provide fundamental information critical for development of assisted reproductive technologies for the Baird's tapir.

The influence of oral progestin (altrenogest; ALT) on cat ovarian activity was studied using non-invasive fecal steroid monitoring. Queens were assigned to various ALT dosages: (1) 0mg/kg (control; n=5 cats); (2) 0.044 mg/kg (LOW; n=5); (3) 0.088 mg/kg (MID; n=6); or (4) 0.352 mg/kg (HIGH; n=6). Fecal estrogen and progestagen concentrations were quantified using enzyme immunoassays for 60 days before, 38 days during and 60 days after ALT treatment. Initiation of follicular activity was suppressed in all cats during progestin treatment, whereas controls continued to cycle normally. Females (n=6) with elevated fecal estrogens at treatment onset completed a normal follicular phase before returning to baseline and remained suppressed until treatment withdrawal. All cats receiving oral progestin re-initiated follicular activity after treatment, although MID cats experienced the most synchronized return (within 10-16 days). Mean baseline fecal estrogens and progestagens were higher (P<0.05) after treatment in HIGH, but not in LOW or MID cats compared to pre-treatment values. The results demonstrate that: (1) oral progestin rapidly suppresses initiation of follicular activity in the cat, but does not influence a follicular phase that exists before treatment initiation; and (2) queens return to normal follicular activity after progestin withdrawal. This study provides foundational information for research aimed at using progestin priming to improve ovarian response in felids scheduled for ovulation induction and assisted breeding., ((c) 2010 Elsevier Inc. All rights reserved.)

Suppression and subsequent rebound of ovarian activity using a progestin (levonorgestrel; Norplant) versus a GnRH antagonist (antide) was assessed in the domestic cat via fecal estradiol and progesterone metabolite analyses. Following an initial dose-response trial, queens were assigned to one of four treatments: (1) antide, two 6 mg/kg injections 15 days apart (n = 8 cats); (2) levonorgestrel, six silastic rods (36 mg levonorgestrel/rod) implanted for 30 days (n = 8); (3) control injections (n = 5); and (4) control implants (n = 5). Steroid metabolites were quantified from daily fecal samples for 90 days before, 30 days during, and 90 days after treatment. Antide and levonorgestrel inhibited estrous cyclicity in contrast to continued cyclicity in controls. Cats already at estradiol baseline in antide (n = 7) and levonorgestrel (n = 4) groups remained inhibited during treatment. In females with elevated estradiol levels at treatment onset (Day 0), a normal estradiol surge was completed before concentrations declined to baseline (approximately Days 5-7) and remained suppressed throughout the remaining treatment period. Additionally, 56% of treatment animals exhibited at least one spontaneous ovulation during the pre-treatment period, but no female ovulated during treatment with levonorgestrel or antide. Antide-treated cats exhibited lower (P < 0.05) baseline estradiol concentrations during treatment compared to pre- and post-treatment. In contrast, levonorgestrel induced elevations in baseline estradiol following treatment compared to pre- and during treatment intervals. Control females showed no change (P > 0.05) in baseline estradiol throughout the study period. All levonorgestrel and antide cats returned to estrus after treatment withdrawal. Results demonstrate that: (1) both antide and levonorgestrel are effective for inducing short-term suppression of follicular recruitment and ovulation in the cat; (2) inhibition is reversible; and (3) GnRH antagonists and progestins differentially regulate basal estradiol secretion. This study also confirmed a relatively high incidence of spontaneous ovulation in the cat, a species generally considered to be an induced ovulator.

Effects of osmolality stresses on the sperm of normospermic (>60% normal sperm/ejaculate) versus teratospermic (<40% normal sperm) domestic cats and the normospermic leopard cat and the teratospermic clouded leopard were studied. Spermatozoa were exposed to various anisotonic solutions in a single step or returned to near isotonic conditions in a single step after exposure to anisotonic solutions. The percentage of sperm motility was measured subjectively, and dual fluorescent stains were used to assess membrane integrity by flow cytometry. The percentage of sperm motility declined (P < 0.05) in domestic cat sperm exposed to osmolalities <200 and >450 mOsm. Spermatozoa from all felines underwent marked (P < 0.05) membrane disruption following a hypotonic stress, but sperm from teratospermic donors experienced greater (P < 0.05) membrane disruption in response to decreased osmolality. While feline spermatozoa appeared to be highly resistant to hypertonic (600, 1200, and 2400 mOsm) conditions, with >85% of the cells maintaining intact membranes, severe membrane disruption occurred when cells were returned to isotonicity in a single step. There was no difference (P > 0.05) between a 1- and 5-min exposure to various anisotonic solutions. Similarly, sperm from normospermic and teratospermic domestic cats responded identically after exposure to ionic or nonionic solute. Results demonstrate that: (1) spermatozoa from teratospermic males are more vulnerable to a hypotonic stress than sperm from normospermic counterparts; (2) in response to small deviations in osmolality, feline sperm experience a more rapid decline in motility than membrane integrity; and (3) an abrupt return to isotonicity after a hypertonic stress causes extensive sperm membrane damage regardless of ejaculate quality., (Copyright 2000 Academic Press.)

Freeze-thawing cat sperm in cryoprotectant results in extensive membrane damage. To determine whether cooling alone influences sperm structure and viability, we compared the effect of cooling rate on sperm from normospermic (N; > 60% normal sperm per ejaculate) and teratospermic (T; < 40% normal sperm per ejaculate) domestic cats. Electroejaculates were divided into raw or washed (Ham's F-10 + 5% fetal calf serum) aliquots, with the latter resuspended in Ham's F-10 medium or Platz Diluent Variant Filtered without glycerol (20% egg yolk, 11% lactose). Aliquots were 1) maintained at 25 degrees C (no cooling; control), 2) cooled to 5 degrees C in a commercial refrigerator for 30 min (rapid cooling; approximately 4 degrees C/min), 3) placed in an ice slush at 0 degrees C for 10 min (ultrarapid cooling; approximately 14 degrees C/min), or 4) cooled to 0 degrees C at 0.5 degrees C/min in a programmable alcohol bath (slow cooling); and aliquots were removed every 4 degrees C. All samples then were warmed to 25 degrees C and evaluated for percentage sperm motility and the proportion of intact acrosomes using a fluorescein-conjugated peanut agglutinin stain. In both cat populations, sperm percentage motility remained unaffected (p > 0.05) immediately after exposure to low temperatures and after warming to 25 degrees C. However, the proportion of spermatozoa with intact acrosomes declined (p < 0.05) after rapid cooling ( approximately 4 degrees C/min) to 5 degrees C (N, 65.6%; T, 27.5%) or ultrarapid cooling ( approximately 14 degrees C/min) to 0 degrees C (N, 62.1%; T, 23.0%) in comparison to the control value (N, 81.5%; T, 77.5%). Transmission electron microscopy of cooled sperm revealed extensive damage to acrosomal membranes. In contrast, slow cooling (0.5 degrees C/min) to 5 degrees C maintained (p > 0.05) a high proportion of spermatozoa with intact acrosomes (N, 75.5%; T, 68.3%), which also remained similar (p > 0.05) between cat populations (N, 64.7%; T, 56.8%) through continued cooling to 0 degrees C. Results demonstrate that 1) rapid cooling of domestic cat sperm induces significant acrosomal damage without altering sperm motility, 2) spermatozoa from teratospermic males are more susceptible to cold-induced acrosomal damage than normospermic counterparts, and 3) reducing the rate of initial cooling markedly decreases sperm structural damage.