Epistaxis related to exercise-induced pulmonary haemorrhage in South African Thoroughbreds

Weideman, H.; Schoeman, S.J.; Jordaan, G.F.; Kidd, Mark

doi:10.4102/jsava.v74i4.525

Cited by 21 publications

(34 citation statements)

References 12 publications

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“…Increasing age has been suggested to be associated with epistaxis in horses, with horses aged ≥5 years being up to 6.4 times more likely to have epistaxis compared to 2‐year‐old horses (Takahashi et al . 2001; Weideman et al . 2003) although neither study controlled for the confounding effect of increased numbers of lifetime starts, which would be expected to be highly correlated with age in most horses.…”

Section: Discussionmentioning

confidence: 99%

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Risk factors for exercise‐induced pulmonary haemorrhage in Thoroughbred racehorses

Hinchcliff¹,

Morley

Jackson

et al. 2010

Equine Veterinary Journal

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SummaryReasons for performing study: Risk factors for occult exerciseinduced pulmonary haemorrhage (EIPH) are poorly defined or quantified. Objectives: To investigate the importance of putative risk factors for EIPH amongst Thoroughbred racehorses in Australia. Methods: Tracheobronchoscopy was used to determine EIPH status of 744 Thoroughbred racehorses after flat racing in Melbourne, Australia. Horses were identified for study before racing, and over 50% of horses racing during the study period were examined. Statistical analysis included use of bivariate and multivariate logistic regression analysis to account for simultaneous effects of a large number of variables. Results: The only risk factor identified as associated with both EIPH Ն1 or Ն2 was ambient temperature, with horses racing at temperatures <20°C being at~2 times risk of occult EIPH. There was no association of EIPH with age, sex, weight carried, track hardness, speed of racing, or air quality. Conclusions: There do not appear to be individual risk factors, amongst those examined in this study, that are strongly associated with EIPH. Potential relevance: The risk of developing EIPH cannot be readily determined from a combination of age, race speed, race distance, track hardness or air quality. This study does not provide support for the hypotheses that racing on hard surfaces or in polluted air contributes to the development of EIPH.

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Section: Discussionmentioning

confidence: 99%

“…Studies reporting the assessment of risk factors for EIPH have often used epistaxis as a marker for the disorder (Takahashi et al . 2001; Weideman et al . 2003).…”

Section: Introductionmentioning

confidence: 99%

Risk factors for exercise‐induced pulmonary haemorrhage in Thoroughbred racehorses

Hinchcliff¹,

Morley

Jackson

et al. 2010

Equine Veterinary Journal

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“…Virtually all horses bred and trained for competitive racing show evidence of exercise-induced pulmonary hemorrhage (EIPH), which manifests as bleeding from the nose after exertion or the presence of red blood cells or hemosiderophages in the airways (3,6,21,39,47,53,58,67). The causative mechanism of EIPH was demonstrated experimentally when it was shown that high pulmonary capillary pressures can cause discrete breaks in the endothelium, epithelium, or the entire BGB in mammals (10,50,64,66).…”

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confidence: 99%

Morphometry of the extremely thin pulmonary blood-gas barrier in the chicken lung

Watson¹,

Fu²,

West³

2007

American Journal of Physiology-Lung Cellular and Molecular Phys

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Watson RR, Fu Z, West JB. Morphometry of the extremely thin pulmonary blood-gas barrier in the chicken lung. Am J Physiol Lung Cell Mol Physiol 292: L769-L777, 2007. First published November 17, 2006; doi:10.1152/ajplung.00355.2006.-The gas exchanging region in the avian lung, although proportionally smaller than that of the mammalian lung, efficiently manages respiration to meet the high energetic requirements of flapping flight. Gas exchange in the bird lung is enhanced, in part, by an extremely thin blood-gas barrier (BGB). We measured the arithmetic mean thickness of the different components (endothelium, interstitium, and epithelium) of the BGB in the domestic chicken lung and compared the results with three mammals. Morphometric analysis showed that the total BGB of the chicken lung was significantly thinner than that of the rabbit, dog, and horse (54, 66, and 70% thinner, respectively) and that all layers of the BGB were significantly thinner in the chicken compared with the mammals. The interstitial layer was strikingly thin in the chicken lung (ϳ86% thinner than the dog and horse, and 75% thinner than rabbit) which is a paradox because the strength of the BGB is believed to come from the interstitium. In addition, the thickness of the interstitium was remarkably uniform, unlike the mammalian interstitium. The uniformity of the interstitial layer in the chicken is attributable to a lack of the supportive type I collagen cable that is found in mammalian alveolar lungs. We propose that the surrounding air capillaries provide additional structural support for the pulmonary capillaries in the bird lung, thus allowing the barrier to be both very thin and extremely uniform. The net result is to improve gas exchanging efficiency. capillary stress failure; lung morphology; bird respiratory physiology; air capillary; extracellular matrix; interstitium IN THE VERTEBRATE LUNG, OPTIMAL thickness of the pulmonary blood-gas barrier (BGB) is affected by opposing selective pressures (65). The barrier thickness is minimized to allow efficient exchange of oxygen and carbon dioxide, yet the capillary walls must also be strong enough to withstand high pulmonary capillary pressures that are incurred during extreme physical exertion. The BGB is composed of three layers: capillary endothelium, an interstitial layer or extracellular matrix, and an epithelial layer (Fig. 1). Combined, these cellular layers are relatively thin, usually measuring Ͻ2 m in total thickness under normal conditions (5,33,36). This three-ply ultrastructure of the BGB appears to be evolutionally well conserved over a variety of vertebrate taxa, indicating that its basic structure is efficient and relatively immalleable (18,25,27,31,33). The strength of the pulmonary capillary walls is likely related to the morphometry of the BGB, where the thickness of the interstitium determines the fragility of the capillaries (5). Where the BGB is thinnest, the interstitial layer is composed of only the fused basement membranes of the endothelium and epithelium laye...

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“…This would involve testing stallions' offspring in an epistaxis-challenging environment. As a clear positive relationship between racing at sea level and epistaxis was established 17 , it might be fruitful to challenge the southern African based sires, comparing all offspring produced that raced at sea level, clearly an unfavourable condition. This may shed more light on the predisposition of imported sires of unknown bleeder status and in some instances racing after treatment with furosemide (Lasix), producing more than their share of offspring that suffer epistaxis.…”

Section: Resultsmentioning

confidence: 99%

“…A variety of findings have been reported. These include a positive relationship between EIPH and age 16 , EIPH and the cooler months of the year 7 , EIPH and sex 12 and EIPH as associated with pulmonary haemorrhage and altitude 17 . On the other hand similar studies could not establish any relationship between EIPH and sex 8 , EIPH and the distance raced 15 , while no association was found between EIPH and trainer or going 9 .…”

Section: Introductionmentioning

confidence: 99%

The inheritance of liability to epistaxis in the southern African Thoroughbred

Weideman¹,

Schoeman²,

Jordaan³

2004

J. S. Afr. Vet. Assoc.

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This study was carried out to estimate the heritability of liability to epistaxis in the southern African Thoroughbred population. Data of all horses that suffered epistaxis while racing in southern Africa and Mauritius from 1986 to 2002 and involving 1252 bleeders were analysed. Pedigree data covering the period 1960-1986 was used as required to calculate the incidence of bleeding amongst ancestors of the post-1986 era. Only pedigrees of horses that raced were included in this study as it was not possible to predict whether non-runners would have bled had they raced. Consequently all non-runners and also those that raced overseas in countries where bleeding occurrence was not recorded, were excluded. The heritability of liability method as described by Falconer (1989) was used to estimate the relative importance of heredity and environment. For the period investigated, the population incidence for epistaxis in southern African horses was 2.1 %. The estimation of heritability of liability showed that 1st-degree relatives had a figure of 55.4 %. Second-degree relatives had a heritability of 41.3 % and 3rd-degree relatives came in at 30.4 %. The heritability of liability shown in this study could be regarded as being at the lower end of the range but could be appreciably higher. The data depict horses that bled almost exclusively on race days, as only a small percentage (~5 %) was reported as having bled during exercise. Accordingly, the full extent of epistaxis amongst racing Thoroughbreds in southern Africa is difficult to gauge. It is clear that epistaxis in the racing Thoroughbred has a strong genetic basis. It is suggested that horses showing frank bleeding from the nostrils after racing or exercise be suspended, and not used for breeding purposes. This should result in relatively fast progress being made towards eradicating this costly scourge of the modern Thoroughbred racehorse

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Epistaxis related to exercise-induced pulmonary haemorrhage in South African Thoroughbreds

Cited by 21 publications

References 12 publications

Risk factors for exercise‐induced pulmonary haemorrhage in Thoroughbred racehorses

Risk factors for exercise‐induced pulmonary haemorrhage in Thoroughbred racehorses

Morphometry of the extremely thin pulmonary blood-gas barrier in the chicken lung

The inheritance of liability to epistaxis in the southern African Thoroughbred

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