Proceedings

Poster n°26
Closure times of the physis in high performance Mangalarga Marchador
Gaited Horses - preliminary findings
K. Moura da Costa Barcelos 1 , A. Souza Carneiro de Rezende 1 , R. Weller 2 , A. M. Quintão Lana 1
and R. Resende Faleiros 1
1 Universidade Federal de Minas Gerais, Escola de Veterinária, Departamento de Pós Graduação em
Zootecnia, Equinotecnia, Pampulha, Belo Horizonte, MG Brasil – Cep 31270901.
2 The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, AL9 7TA, UK
katebar@terra.com.br
The closure of the physes of the long bones is commonly used as a parameter when training
can be started in horses. Mangalarga Marchador (MM) is a gaited horse breed that start
competing in hand at 15 months and being ridden at 39 months of age. This schedule requires
intense training at very young age. To date the closure times of the physes in long bones and
hence skeletal maturity in this breed is unknown. The aim of this study was to determine the
closure times of the distal physis of the tibia and radius in MM horses with the ultimate aim to
guide training programmes and promote animal welfare. Fifty-six sound MM horses that
competed successfully in one type of gaited horse competition (Marcha Picada Gait (MPG) were
included in this study. These animals were the first seven placed horses in four categories in the
National Exhibition in 2014, categorised by type of competition, age and gender: category I:
shown in hand, 7 females (19-29 months) and 7 males (18-21 months), category II: shown in
hand and 7 females (30 to 34) and 7 males (22 to 34); category III: ridden, 7 females (41 to 45)
and 7 males (41 to 53) and category IV: ridden, 7 females (54 to 56) and 7 males (53 to 58).
Three radiographs were taken of each horse: a cranio-caudal radiograph centred on the left and
right distal radius and the left distal tibia using a digital radiography system (Orange 90® x-ray
generator in combination with a Claro X DR system) with a focus-film distance of 60 cm, kV
between 70-73 and 3.2 mAs. The radiographs were graded for physis closure by a single
observer (RW) into: open-A, partially closed-B and fully closed-C. Data distribution of groups and
homoscedasticity variances were checked using Lilliefors tests and Cochran, and the data were
analysed using descriptive statistics. The physis closure results for radius and tibia were are the
same. The initial closing time, grade B, began in females (29%) in category I, and in males
(43%) in category II. In all horses physes full closure occurred earlier in females in category III
and later in males in category IV. This results suggests physis closure time begin to take place
between 22-34 months and ends between 41-58 months. This wide variation may be related
directly to the type of feeding and training management, and additionally the genetic breed
variation. More studies are needed to compare these findings with horses in the same breed not
subjected to intense exercise, under the same management and feeding thus evaluating the
influence of exercise on the growth of these animals in order to better guide and improve MM
horse training.
Lay person message: The MM Horse MPG begins participation in competitions at 15 months
when the cartilage of long bones has not yet ossified. Ossification begins to take place between
22-34 months and ends between 41-58 months. This wide variation indicates that exercise,
management and feeding of high performance horses may in combination influence
mineralization.
Keywords: gaited horse, Marcha Picada, growth, physis, training, welfare.
© International Society for Equitation Science 2016
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