Prematurity and Dysmaturity Are Associated With Reduced Height and Shorter Distal Limb Length in Horses

Title
Prematurity and Dysmaturity Are Associated With Reduced Height and Shorter Distal Limb Length in Horses
Publication Date
2020-08
Author(s)
Clothier, Jane
( author )
OrcID: https://orcid.org/0000-0001-8215-158X
Email: jclothi5@une.edu.au
UNE Id une-id:jclothi5
Small, Alison
Hinch, Geoff
( author )
OrcID: https://orcid.org/0000-0003-4731-865X
Email: ghinch@une.edu.au
UNE Id une-id:ghinch
Brown, Wendy Y
( author )
OrcID: https://orcid.org/0000-0002-5309-3381
Email: wbrown@une.edu.au
UNE Id une-id:wbrown
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Elsevier Inc
Place of publication
United States of America
DOI
10.1016/j.jevs.2020.103129
UNE publication id
une:1959.11/51679
Abstract

The long-term effects of gestational immaturity in the premature (defined as < 320 days gestation) and dysmature (normal term but showing some signs of prematurity) foal have not been thoroughly investigated. Studies have reported that a high percentage of gestationally immature foals with related orthopedic issues such as incomplete ossification may fail to fulfill their intended athletic purpose, particularly in Thoroughbred racing. In humans, premature birth is associated with shorter stature at maturity and variations in anatomical ratios, linked to alterations in metabolism and timing of physeal closure in the long bones. We hypothesized that gestational immaturity in horses might similarly be associated with reduced height and different anatomical ratios at maturity. In this preliminary study, the skeletal ratios of horses with a history of gestational immaturity, identified through veterinary and breeder records, were compared with those of unaffected, closely related horses (i.e., sire, dam, sibling). External measurements were taken from conformation photographs of cases (n = 19) and related horses (n = 28), and these were then combined into indices to evaluate and compare metric properties of conformation. A principal component analysis showed that the first two principal components account for 43.8% of the total conformational variation of the horses' external features, separating horses with a rectangular conformation (body length > height at the withers), from those that are more square (body length = height at the withers). Varimax rotation of PC1 and analysis of different gestational groups showed a significant effect of gestational immaturity (P = .001), with the premature group being more affected than the dysmature group (P = .009, P = .012). Mean values for the four dominant indices showed that these groups have significantly lower distal limb to body length relationships than controls. The observed differences suggest that gestational immaturity may affect anatomical ratios at maturity, which, in combination with orthopedic issues arising from incomplete ossification, may have a further impact on long-term athletic potential.

Link
Citation
Journal of Equine Veterinary Science, v.91, p. 1-7
ISSN
1542-7412
0737-0806
Start page
1
End page
7

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