Employee perception of precision technology use at the dairy farm.

The adoption of precision technologies on dairy farms has increased significantly in recent decades, leading to the challenge of providing employees with resources to maximize the efficient use of these tools. The objective of this study was to explore how dairy farm employees perceive the available precision technologies and to identify possible challenges they face when adapting to their use at the farm. An online survey consisting of four sections (employee demographics, precision technologies in use, perception of these technologies, and opportunities for adapting to technology use) was completed from September to December 2022 by 266 farm employees from three dairies operated under similar management. Most of the respondents were identified as male (72.2%), Hispanic or Latino (92.5%), aged between 21 and 30 (39.1%) or 31 and 40 yr (36.8%), with a bachelor's degree (34.6%) or completion of middle school (29.3%) and having basic or no English proficiency (74%). Overall, the respondents indicated being comfortable (95.6%) with and understanding (91.8%) the technology they use. Employees recognized precision technology as a tool that helps them to be more efficient (93.7%), identifying the technologies' benefits (92.1%). However, challenges for adapting to these technologies included personal limitations, such as not knowing the language of the technology (31%), visual impairments (24%), light sensitivity (14%), and not being able to read (7%). Environmental limitations were also recognized and included cold weather (64.3%), wind (46%), and surroundings that were too dark (31%) or too bright (21%). Significant associations between perception of the technology and age, level of education, and English proficiency were identified. Respondents indicated their desire to learn more about precision technologies implemented at work, which could eventually lead to improved efficiency at the dairy operation through innovations in the way users interact with these technologies, increasing employees' motivation. This study provides insights that could assist the dairy industry in addressing challenges and enhancing opportunities for a more efficient use of precision technologies at dairy farms.

Genetic parameters for pulmonary arterial pressure, yearling performance, and carcass ultrasound traits in Angus cattle.

Pulmonary arterial pressure (PAP) can be used as an indicator of susceptibility to pulmonary hypertension and subsequent potential to develop right-sided heart failure (RHF). Previously reported heritability estimates of PAP have been moderate to high. Based on these estimates, selection for the indicator trait, PAP, could reduce the incidence of RHF due to hypoxia. Previous studies have also speculated that increased growth rates and body fat accumulation contribute to increased PAP and RHF. Research evaluating the genetic relationships between PAP and performance traits (e.g., yearling weight and postweaning gain) has yielded conflicting results, leading to ambiguity and uncertainty regarding the underlying genetic relationships. Additionally, no previous research has evaluated the relationship between PAP and ultrasound carcass traits. Therefore, the objective of this study was to estimate trait heritabilities and genetic correlations between PAP, post-weaning growth traits, and ultrasound carcass traits in Angus cattle, using data (n = 4,511) from the American Angus Association. We hypothesized that traits associated with increased growth and muscle would have a positive genetic (i.e., unfavorable) relationship with PAP. Estimates for heritability and genetic correlations were obtained using a multi-trait animal model. Heritability estimates for PAP (0.21 ± 0.04), post-weaning gain (PWG; 0.31 ± 0.04), and yearling weight (YWT; 0.37 ± 0.04) were within the range of estimates previously reported. Genetic correlations were weak (< 0.20) between PAP, PWG, and YWT. A low-to-moderate genetic correlation between PAP and ultrasound ribeye area (UREA) was found (0.25 ± 0.12). Genetic correlations between PAP, ultrasound back fat (UBF), ultrasound intramuscular fat (IMF), and ultrasound rump fat (RUMP) were weak (ranging in magnitude from -0.05 to 0.10) and therefore, do not provide strong support for the hypothesis of an antagonistic relationship between PAP and carcass ultrasound traits, while heritability estimates for UBF (0.43 ± 0.05), UREA (0.31 ± 0.04), IMF (0.35 ± 0.04), and RUMP (0.47 ± 0.05) were in the range of previously reported values.

Beef cattle residing >1,500 m are subject to reduced atmospheric oxygen levels when compared with beef cattle at lower elevations which may result in hypoxia-induced pulmonary hypertension and right-side heart failure. Breeders use pulmonary arterial pressures to identify animals at risk of right-side heart failure and to select breeding animals that are less susceptible to the problem. There is a concern that selection for growth and carcass characteristics may be increasing the incidence of heart failure in feedlot cattle at elevations <1,500 m. To address the concern, this study estimated the genetic correlations (i.e., relationships) between pulmonary arterial pressure, growth, and ultrasound carcass measures in Angus cattle. The study shows that the genetic relationships between pulmonary arterial pressure and these traits are minimal to non-existent with the exception of ultrasound ribeye area. Our estimate suggests a moderate, unfavorable relationship between pulmonary arterial pressure and ribeye area and that single-trait selection for increased ribeye area alone may result in increased susceptibility to right-side heart failure. However, selection for both traits simultaneously should overcome increases in susceptibility given the moderate strength of the genetic relationship.

Functional and molecular determinants of right ventricular response to severe pulmonary hypertension in a large animal model.

Right ventricular (RV) failure is the major determinant of outcome in pulmonary hypertension (PH). Calves exposed to 2-wk hypoxia develop severe PH and unlike rodents, hypoxia-induced PH in this species can lead to right heart failure. We, therefore, sought to examine the molecular and structural changes in the RV in calves with hypoxia-induced PH, hypothesizing that we could identify mechanisms underlying compensated physiological function in the face of developing severe PH. Calves were exposed to 14 days of environmental hypoxia (equivalent to 4,570 m/15,000 ft elevation, n = 29) or ambient normoxia (1,525 m/5,000 ft, n = 25). Cardiopulmonary function was evaluated by right heart catheterization and pressure volume loops. Molecular and cellular determinants of RV remodeling were analyzed by cDNA microarrays, RealTime PCR, proteomics, and immunochemistry. Hypoxic exposure induced robust PH, with increased RV contractile performance and preserved cardiac output, yet evidence of dysregulated RV-pulmonary artery mechanical coupling as seen in advanced disease. Analysis of gene expression revealed cellular processes associated with structural remodeling, cell signaling, and survival. We further identified specific clusters of gene expression associated with 1) hypertrophic gene expression and prosurvival mechanotransduction through YAP-TAZ signaling, 2) extracellular matrix (ECM) remodeling, 3) inflammatory cell activation, and 4) angiogenesis. A potential transcriptomic signature of cardiac fibroblasts in RV remodeling was detected, enriched in functions related to cell movement, tissue differentiation, and angiogenesis. Proteomic and immunohistochemical analysis confirmed RV myocyte hypertrophy, together with localization of ECM remodeling, inflammatory cell activation, and endothelial cell proliferation within the RV interstitium. In conclusion, hypoxia and hemodynamic load initiate coordinated processes of protective and compensatory RV remodeling to withstand the progression of PH.NEW & NOTEWORTHY Using a large animal model and employing a comprehensive approach integrating hemodynamic, transcriptomic, proteomic, and immunohistochemical analyses, we examined the early (2 wk) effects of severe PH on the RV. We observed that RV remodeling during PH progression represents a continuum of transcriptionally driven processes whereby cardiac myocytes, fibroblasts, endothelial cells, and proremodeling macrophages act to coordinately maintain physiological homeostasis and protect myocyte survival during chronic, severe, and progressive pressure overload.

Brief Report: Case Comparison of Therapy With the Histone Deacetylase Inhibitor Vorinostat in a Neonatal Calf Model of Pulmonary Hypertension.

Pulmonary hypertension (PH) is an incurable condition in humans; driven by pulmonary vascular remodeling partially mediated by epigenetic mechanisms; and leading to right ventricular hypertrophy, failure, and death. We hypothesized that targeting chromatin-modifying histone deacetylases may provide benefit. In this Brief Report we describe case comparison studies using the histone deacetylase inhibitor vorinostat (suberanilohydroxamic acid, 5 mg/kg/day for the first 5 study days) in an established model of severe neonatal bovine PH induced by 14 days of environmental hypoxia. Echocardiographic, hemodynamic, and pharmacokinetic data were obtained in hypoxia-exposed (one each, vorinostat-treated vs. untreated) and normoxic vorinostat-treated control animals (n = 2). Echocardiography detected PH changes by day 4 and severe PH over 14 days of continued hypoxic exposure. RV dysfunction at day 4 was less severe in vorinostat-treated compared to untreated hypoxic calves. Cardioprotective effects were partially maintained following cessation of treatment through the duration of hypoxic exposure, accompanied by hemodynamic evidence suggestive of reduced pulmonary vascular stiffening, and modulated expression of HDAC1 protein and genes involved in RV and pulmonary vascular remodeling and pathological RV hypertrophy. Control calves did not develop PH, nor show adverse cardiac or clinical effects. These results provide novel translation of epigenetic-directed therapy to a large animal severe PH model that recapitulates important features of human disease.

Investigation of neonatal disorders in New World camelids and factors associated with death during and after hospitalization of affected crias.

OBJECTIVE: To assess signalment, clinical findings, and treatments for New World camelids (NWCs) hospitalized for evaluation and treatment of neonatal disorders and investigate associations between these factors and death during and after hospitalization. ANIMALS: 267 NWCs ≤ 30 days of age. PROCEDURES: Medical records of a veterinary teaching hospital were retrospectively reviewed to identify NWCs admitted for evaluation and treatment of neonatal disorders between 2000 and 2010. Signalment, physical examination data, diagnostic findings, treatments, and outcomes were recorded. Factors were examined for association with death during hospitalization and the overall hazard of death by use of multivariable logistic regression and Cox proportional hazards analysis, respectively. RESULTS: The sample comprised alpacas (n = 255) and llamas (12). Median age at admission was 3 days, and median hospitalization time was 2 days; 208 of the 267 (77.9%) neonatal NWCs survived to hospital discharge. Factors associated with increased odds of death during hospitalization included prematurity or dysmaturity, hypothermia, sepsis, toxic changes in neutrophils, and undergoing surgery. The odds of death during hospitalization also increased as anion gap increased. After discharge, 151 of 176 (85.8%) animals had follow-up information available (median follow-up time, 2,932 days); 126 (83%) were alive and 25 (17%) had died. Prematurity or dysmaturity, congenital defects, sepsis, oxygen administration, and undergoing surgery as a neonate were associated with an increased hazard of death; the hazard of death also increased as serum chloride concentration at the time of hospitalization increased. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested the prognosis for survival during and after hospitalization is good for most NWCs hospitalized because of neonatal disorders.

Evaluation of the sensitivity of pulmonary arterial pressure to elevation using a reaction norm model in Angus Cattle.

Pulmonary arterial pressure (PAP) is a diagnostic measure used to determine an individual's susceptibility to developing high-altitude disease. The importance of PAP measures collected at elevations lower than the intended breeding elevation of the bulls (i.e., ≥1,520 m) is unknown. Therefore, the objective of this study was to determine the genetic relationship between PAP measures collected in a range of elevations using reaction norm models. A total of 9,177 PAP and elevation observations on purebred Angus cattle, which averaged 43.49 ± 11.32 mmHg and 1,878.6 ± 296.8 m, respectively, were used in the evaluation. The average age of the individuals in the evaluation was 434.04 ± 115.9 d. A random regression model containing the effects of sex, a linear covariate of age, a quadratic fixed covariate of elevation, and random effects consisting of a contemporary group and a linear regression of PAP on elevation was used for the evaluation of PAP. Two forms of PAP were evaluated with this model. First, to address the non-normality of the data, PAP was raised to the power of -2.6 (ptPAP) based on the results of a Box-Cox analysis. Second, raw PAP (rPAP) phenotypes were evaluated to compare the results to those obtained from the transformed data. For ptPAP, heritability ranged from 0.25 to 0.37 corresponding to elevations of 1,900 and 1,215 m, respectively. For rPAP, heritability ranged from 0.22 to 0.41 corresponding to elevations of 1,700 and 2,495 m, respectively. Generally, lower elevations corresponded to decreased heritabilities while higher elevations corresponded to increased heritability estimates. For ptPAP, genetic correlations ranged from 0.18 (elevation: 1,215 and 2,495 m) to 1.00. For rPAP, genetic correlations ranged from 0.08 (elevation: 1,215 and 2,495 m) to 1.00. In general, the closer the elevations in which PAP was measured, the greater the genetic relationship. The greater the difference in elevation between PAP measures resulted in lower genetic correlations. The rank correlation between expected progeny differences (EPD) for 1,215 and 2,495 m was 0.65 and 0.49 for the ptPAP and rPAP, respectively. These results suggested that PAP measures collected in lower elevations may be used as an indicator of high-altitude adaptability. In the estimation of EPD to rank sires for their suitability for use in high-elevation production systems, it is important to account for the relationships among varied altitudes.

Laparoscopic ovariohysterectomy in goats.

OBJECTIVE To describe a minimally invasive 3-portal laparoscopic approach for elective ovariohysterectomy and the outcome of that procedure in a population of goats. DESIGN Descriptive clinical study. ANIMALS 16 healthy client-owned goats. PROCEDURES Food but not water was withheld from all goats for 24 hours before the procedure. Goats were anesthetized and positioned in dorsal recumbency. Three laparoscopic portals were created in the caudoventral portion of the abdomen, and the abdomen was insufflated to a maximum pressure of 10 mm Hg. A blunt-tip vessel sealer and divider device was used to transect the left and right mesovarium and mesometrium and uterus, and the resected tissue was removed from the abdomen. After hemostasis was verified, the portals were closed in a routine manner and anesthesia was discontinued. Goats were discharged from the hospital 24 hours after the procedure, and owners were contacted by telephone or email to obtain short- and long-term follow-up information by use of standardized questions. RESULTS All procedures were performed by a surgeon and assistant surgeon. The procedure was not complex and was easily learned. No intraoperative complications were reported, and only 1 goat required rescue analgesia post-operatively. No other postoperative complications were recorded. Median surgery time was 43 minutes (range, 20 to 65 minutes). All owners were satisfied with the outcome of the procedure, and several perceived that the procedure improved goat behavior. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that laparoscopic ovariohysterectomy was a viable alternative for elective sterilization of female goats.

Cardiopulmonary remodeling in fattened beef cattle: a naturally occurring large animal model of obesity-associated pulmonary hypertension with left heart disease.

The obesity epidemic in developed societies has led to increased cardiovascular diseases including pulmonary hypertension associated with left heart disease (PH-LHD), the largest and fastest-growing class of PH. Similar to obese humans, PH and heart failure (HF) are increasingly recognized in North American fattened beef cattle. We hypothesized that PH and HF in fattened beef cattle are novel, phenotypically distinct manifestations of bovine PH arising from left ventricular (LV) dysfunction similar to obesity-related PH-LHD in humans. We conducted a semi-quantitative histopathological assessment of cardiopulmonary tissues obtained from fattened beef cattle suffering end-stage HF compared to asymptomatic cattle of equivalent age undergoing the same fattening regimens. In HF animals we observed significant LV fibrosis, abundant cardiac adipose depots, coronary artery injury, and pulmonary venous remodeling recapitulating human obesity-related PH-LHD. Additionally, striking muscularization, medial hypertrophy, adventitial fibrosis, and vasa vasorum hyperplasia in the pulmonary arterial circulation were associated with sequela of pathologic right ventricular (RV) remodeling suggesting combined pulmonary venous and arterial hypertension. The association between obesity, pathologic cardiopulmonary remodeling, and HF in fattened beef cattle appears to recapitulate the complex pathophysiology of obesity-associated PH-LHD in humans. This novel, naturally occurring, and large animal model may provide mechanistic and translational insights into human disease.

Evaluation of moderate to high elevation effects on pulmonary arterial pressure measures in Angus cattle1.

Altitude-induced pulmonary hypertension is a disease once thought to only occur at extremely high elevations (>1,600 m), but recently, it has been observed at moderate elevations of 1,200 to 1,600 m. Pulmonary arterial pressure (PAP) has been used as an indicator of tolerance to high altitude in mountainous beef production systems for over 30 yr. The trait is typically measured on yearling bulls and heifers with values ≤ 41 mmHg being favorable. These observations were historically only considered valid when they were recorded at elevations ≥ 1,600 m; however, if observations from lower (i.e., moderate) elevations were reliable indicators, a greater number of cattle records could be used in genetic improvement programs for high-altitude beef systems. The objectives of this study were to evaluate the relationship between PAP and elevation, as well as to determine whether PAP measures obtained at moderate elevations (ME) less than 1,600 m have a genetic relationship with PAP observations obtained at high elevations (HE) 1,600 m or greater. Elevation and PAP data from purebred Angus cattle (n = 14,665) from 349 contemporary groups were used in the analyses. Elevation and PAP averaged 1,887 ± 1.8 m and 43.0 ± 0.1 mm Hg, respectively. A univariate model containing the effects of sex, age, elevation category (HE vs. ME), elevation (continuous), and elevation category by elevation interaction along with a random direct genetic effect was utilized to determine the relationship between PAP and elevation. In this model, all main effects were found to be significant contributors of variation in PAP (P < 0.001). The interaction between elevation category and elevation was not a significant contributor to variability of PAP (P > 0.05). A bivariate animal model was then used to evaluate the relationship between PAP observations obtained between HE and ME groups. Heritability estimates for these 2 groups were 0.34 ± 0.03 and 0.29 ± 0.09, respectively, and their genetic correlation was 0.83 ± 0.15. Even though this is a strong genetic relationship, results of this study support the hypothesis that PAP observations collected at HE and ME are not perfectly, genetically related. Results suggest that PAP measures collected from 1,219 to 1,600 m may be useful as a correlated trait in a multitrait genetic evaluation to produce EPD useful for selection of animals with reduced susceptibility to pulmonary hypertension.

School-Based Interprofessional Asthma Self-Management Education Program for Middle School Students: A Feasibility Trial.

BACKGROUND: Asthma is the most common chronic disease among school-aged children under 18 years of age and is a major cause of morbidity, loss of school days, and increased hospitalizations. Asthma disproportionately affects low-income, minority youth in Alabama. The benefits of improving asthma control and self-management have significance for improving health, preventing disease, and reducing health disparities by addressing social, behavioral, environmental, economic, and medical determinants of health. OBJECTIVES: This collaborative community partnership between the Mobile County Public School System, University of South Alabama (USA), and USA Children's and Women's Hospital involved nursing students, respiratory therapy students, and medical residents from three colleges and the hospital. The research question was whether a school-based asthma self-management education program presented by an interprofessional team was feasible for teens with asthma in a medically underserved area (MUA). METHODS: Middle school students with a diagnosis of asthma participated in this institutional review board-approved study. Asthma assessments, one-on-one coaching, and group education were done over five sessions, using Power Breathing for teens curriculum. Instruments were the Childhood Asthma Control Test (ACT), the Asthma Responsibility Questionnaire (ARQ), the Self-Efficacy Scale, the Pediatric Asthma Quality of Life Questionnaire (PAQLQ), peak flow monitoring, and spirometry. RESULTS: Eighteen students with moderate to severe persistent asthma completed the program with reduced asthma symptoms and increased asthma control, medication knowledge/skills, self-efficacy, and asthma responsibility. CONCLUSIONS: Adolescents with asthma need education in medication management, spacer use, peak flow, trigger avoidance, and coaching to take on the responsibility of asthma care. This multidimensional, interprofessional approach can strengthen asthma self-management in a middle school medically underserved community population.

Surgical Revision after Sacroiliac Joint Fixation or Fusion.

BACKGROUND: Minimally invasive sacroiliac joint (SIJ) fusion has been shown to be safe and effective for the treatment of SIJ dysfunction. Multiple devices are available to perform SIJ fixation or fusion. Surgical revision rates after these procedures have not been directly compared. METHODS: We retrospectively identified all patients in our practice who underwent SIJ fixation or fusion between 2003 and 2015. Using both chart review and focused contact with individual patients, we determined the likelihood of surgical revision. Revision rates were compared using Kaplan-Meier survival analysis. RESULTS: Thirty-eight patients underwent SIJ fixation with screws and 274 patients underwent SIJ fusion using triangular titanium implants. Four-year cumulative revision rates were 30.8% for fixation and 5.7% for fusion. CONCLUSIONS: In our study, SIJ fixation with screws had a much higher revision rate compared to SIJ fusion with triangular titanium implants designed for bone adherence.

Laparoscopic inguinal hernioplasty in a ram.

CASE DESCRIPTION: A 4-month-old Hampshire ram underwent open right inguinal herniorrhaphy and unilateral castration following herniation that developed after a kick injury. Seven months later, the ram was reevaluated because of scrotal swelling of 1 month's duration as well as suspected left inguinal hernia. CLINICAL FINDINGS: The ram had marked scrotal swelling. Palpation of the left testicle revealed no abnormalities. Ultrasonographic examination revealed heterogenous tissue within the cranial and medial portions of the scrotum with pronounced accumulation of hypoechoic fluid at the scrotal apex. Examination findings indicated left-sided indirect inguinal herniation of omentum. TREATMENT AND OUTCOME: To preserve fertility, left inguinal hernioplasty without castration was performed. The ram was anesthetized and placed in dorsal recumbency, and laparoscopic abdominal evaluation revealed omental entrapment within the left inguinal ring. The omentum was removed, and a polypropylene mesh was secured over the internal inguinal ring with an articulating hernia stapler. Following mesh placement, a dorsally based peritoneal flap was elevated and secured over the mesh repair. The ram recovered well from surgery; there was no repeated herniation following the surgical correction, and the ram was able to breed successfully without complication. CLINICAL RELEVANCE: Laparoscopic mesh hernioplasty can be successful in rams with inguinal hernias when preservation of fertility is preferred.

Increased prevalence of EPAS1 variant in cattle with high-altitude pulmonary hypertension.

High-altitude pulmonary hypertension (HAPH) has heritable features and is a major cause of death in cattle in the Rocky Mountains, USA. Although multiple genes are likely involved in the genesis of HAPH, to date no major gene variant has been identified. Using whole-exome sequencing, we report the high association of an EPAS1 (HIF2α) double variant in the oxygen degradation domain of EPAS1 in Angus cattle with HAPH, mean pulmonary artery pressure >50 mm Hg in two independent herds. Expression analysis shows upregulation of 26 of 27 HIF2α target genes in EPAS1 carriers with HAPH. Of interest, this variant appears to be prevalent in lowland cattle, in which 41% of a herd of 32 are carriers, but the variant may only have a phenotype when the animal is hypoxemic at altitude. The EPAS1 variant will be a tool to determine the cells and signalling pathways leading to HAPH.

One-year outcomes after minimally invasive sacroiliac joint fusion with a series of triangular implants: a multicenter, patient-level analysis.

BACKGROUND: Sacroiliac joint (SI) pain is an often-overlooked cause of lower-back pain, due in part to a lack of specific findings on radiographs and a symptom profile similar to other back-related disorders. A minimally invasive surgical (MIS) approach to SI joint fusion using a series of triangular, titanium plasma spray-coated implants has shown favorable outcomes in patients with SI joint pain refractory to conservative care. The aim of this study was to provide a multicenter experience of MIS SI joint fusion using a patient-level analysis. PATIENTS AND METHODS: We report a patient-level analysis from 144 patients with a mean of 16 months postoperative follow-up. Demographic information, perioperative measures, complications, and clinical outcomes using a visual analog scale for pain were collected prospectively. Random-effects regression models were used to account for intersite variability. RESULTS: The mean age was 58 years, 71% of patients were female, and 62% had a history of lumbar spinal fusion. Mean (95% confidence interval [CI]) operative time was 73 minutes (25.4-118), blood loss was minimal, and hospital stay was 0.8 days (0.1-1.5). At follow-up, mean (95% CI) visual analog scale pain scores improved by 6.1 points (5.7-6.6). Substantial clinical benefit, defined as a decrease in pain by >2.5 points or a score of 3.5 or less, was achieved in 91.9% of patients (95% CI 83.9%-96.1%), and 96% (95% CI 86.3%-98.8%) of patients indicated they would have the same surgery again. CONCLUSION: When conservative measures fail to relieve symptoms resulting from degeneration or disruption of the SI joint, MIS SI joint fusion using a series of triangular, porous, titanium plasma spray-coated implants is a safe and effective treatment option.

Myosin heavy chain 15 is associated with bovine pulmonary arterial pressure.

Bovine pulmonary hypertension, brisket disease, causes significant morbidity and mortality at elevations above 2,000 m. Mean pulmonary arterial pressure (mPAP) is moderately heritable, with inheritance estimated to lie within a few major genes. Invasive mPAP measurement is currently the only tool available to identify cattle at risk of hypoxia-induced pulmonary hypertension. A genetic test could allow selection of cattle suitable for high altitude without the need for invasive testing. In this study we evaluated three candidate genes (myosin heavy chain 15 [MYH15], NADH dehydrogenase flavoprotein 2, and FK binding protein 1A) for association with mPAP in 166 yearling Angus bulls grazing at 2,182 m. The T allele (rs29016420) of MYH15 was linked to lower mPAP in a dominant manner (CC 47.2 ± 1.6 mmHg [mean ± standard error of the mean]; CT/TT 42.8 ± 0.7 mmHg; P = 0.02). The proportions of cattle with MYH15 CC, CT, and TT genotypes were 55%, 41%, and 4%, respectively. Given the high frequency of the deleterious allele, it is likely that the relative contribution of MYH15 polymorphisms to pulmonary hypertension is small, supporting previous predictions that the disease is polygenic. We evaluated allelic frequency of MYH15 in the Himalayan yak (Bos grunniens), a closely related species adapted to high altitude, and found 100% prevalence of T allele homozygosity. In summary, we identified a polymorphism in MYH15 significantly associated with mPAP. This finding may aid selection of cattle suitable for high altitude and contribute to understanding human hypoxia-induced pulmonary hypertension.