Environmental surveillance and adverse neonatal health outcomes in foals born near unconventional natural gas development activity

Clinical and histopathological features in horses with neuroaxonal degeneration: 100 cases (2017-2021)

BACKGROUND

Adult horses with proprioceptive ataxia and behavior changes that have histologic lesions consistent with neurodegenerative disease have been increasingly recognized.

HYPOTHESIS/OBJECTIVES

Describe the history, clinical findings and histopathologic features of horses presented to a referral institution with neuroaxonal degeneration.

ANIMALS

One hundred horses with a necropsy diagnosis of neuroaxonal degeneration compatible with neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM).

METHODS

Retrospective study of horses presented to the University of Pennsylvania, New Bolton Center, between 2017 and 2021 with a necropsy diagnosis of eNAD/EDM.

RESULTS

Affected horses had a median age of 8 years (range, 1-22), and the majority were Warmbloods (72). Sixty-eight horses had behavioral changes, and all 100 had proprioceptive ataxia (median grade, 2/5). Fifty-seven horses had abnormal findings on cervical vertebral radiographs, and 14 had myelographic findings consistent with compressive myelopathy. No antemortem diagnostic test results were consistently associated with necropsy diagnosis of neurodegenerative disease. All 100 horses had degenerative lesions characteristic of eNAD in the brainstem gray matter, and 24 had concurrent degenerative features of EDM in the spinal cord white matter.

CONCLUSIONS AND CLINICAL IMPORTANCE

Clinical and histopathologic findings in this large group of horses with neurodegenerative disease were most consistent with eNAD/EDM, but with a different signalment and clinical presentation from earlier descriptions. The increasing occurrence of neurodegenerative disease in horses and the safety risk posed emphasize the importance of focused research in affected horses.

Systematic Analysis of Breed, Methodological, and Geographical Impact on Equine Sperm Progressive Motility

Simple Summary

Semen quality is an important indicator of reproductive health and fertility. With adverse temporal trends in human semen quality over the past 50 years paralleled in male animals, there is increasing concern for the causes and implications of perturbed male reproductive health. The evaluation of equine progressive motility (PM), a parameter closely associated with fertility, provides information on the fertilising capacity of equine ejaculate and current reproductive health of the equine stallion. Using systematic analysis, recent trends in equine PM were determined from 696 estimates from 280 individual studies. Temporal trends indicate equine PM has not significantly changed between the years 1990 and 2018. Significant breed, methodological, and geographical variations observed in equine PM may considerably influence actual and reported stallion fertility potential. Information on stallion PM meaningfully contributes to the wider literature on semen quality and provides avenues for future stallion fertility research. This systematic analysis presents the wider challenges associated with semen quality assessment, particularly within the equine sector, and provides recommendations to promote consistency across industry and research.

Abstract

Over the past five decades, there has been increasing evidence to indicate global declines in human semen quality. Parallel adverse trends measured in male animals indicate a potential environmental aetiology. This study evaluated the progressive motility (PM) of stallion ejaculate through a systematic review and meta-analysis. A total of 696 estimates of equine PM from 280 studies, which collected semen samples between the years 1990 and 2018, were collated for meta-analysis. The method of motility analysis, breed, season of collection, and geographical location were extracted. Simple linear regression determined temporal trends in stallion PM. Studies using microscopy estimated PM to be significantly greater compared to computer-automated methods (p ≤ 0.001). For Arabian breeds, PM was consistently higher than other breeds. Over time, there was a significant decline in PM for studies from Europe (n = 267) but a significant increase for studies from North America (n = 259). Temporal trends indicate the fertilising capacity of equine ejaculate has remained consistently high in the last three decades. That being so, variations observed suggest methodological, geographical, and individual stallion differences may significantly influence actual and reported stallion fertility potential.

The effect of neonatal dysphagia on subsequent racing performance in Standardbred horses

BACKGROUND

Previously we described a clustering of dysphagic foal cases on a Pennsylvania (PA) Standardbred farm which was associated with exposure of pregnant mares to high concentrations of polycyclic aromatic hydrocarbons (PAHs) in the well water. The effect of dysphagia on future athleticism was uncertain.

OBJECTIVES

To determine if, as adults, dysphagic foals were less likely to race and if athleticism (age of first race, Speed Index and Earnings Per Start Index) differed from that of healthy foals that raced as adults.

STUDY DESIGN

Prospective cohort study.

METHODS

All foals born during the study period (2014-2017) on the affected PA or an unaffected New York (NY) farm with the same proprietor were eligible for inclusion in the study. Foals with dysphagia attributed to causes other than PAH environmental exposure were excluded. The proportion of foals from both farms that raced, their age of first race, Earnings Per Start Index and Speed Index were compared between the dysphagic and normal foals using Chi-Square and Wilcoxon Rank Sum Tests. Significance level was P < .05.

RESULTS

A total of 116 foals met the inclusion criteria. No significant difference was found in the percentages of foals that raced from each farm: On the PA farm, 54% of healthy and 72% of dysphagic foals raced; 70% of healthy NY farm foals raced. Median (interquartile range) age of first race, Earnings Per Start Index or Speed Index for dysphagic foals (2 years (2, 2); 57 (49, 60); 60 (45, 66) was not different from those of healthy foals from both farms (2 years (2, 3); 55 (39, 78)) or the PA farm (2 years (2, 2); 61(24, 73); 68 (57, 85)). All P > .05.

MAIN LIMITATIONS

Small sample size and unique type of dysphagia.

CONCLUSIONS

The athleticism of formerly dysphagic foals does not appear to be negatively impacted compared with normal foals as measured by age of first race, Earnings Per Start Index and Speed Index.