Teresa Margarida Costa Pereira e Curto
Dissertation in Veterinary Medicine
ADVISOR
Doctor Maria da Conceição da Cunha Vasconcelos Peleteiro
CO-ADVISOR
Doctor Maria Luisa Mendes Jorge
Abstract
Since 2008, the high prevalence of acquired flexural limb deformities front was observed in the Lusitano stud farm. This work aims to evaluate this problem by reporting the results from tissue alterations in the affected animals as well as environmental conditions and management changes, which could have led to this observation.
A total of eleven affected animals were studied. In these, a complete physical and orthopedic examination were performed specifically the determination of the angle between the dorsal hoof wall and the floor. Radiographic examination, CT imaging, determination of the thickness of the cortical bone of the third metacarpian and histopathology of some tissues collected in biopsy and necropsy were done in a subset of affected foals. All the animals had been supplemented with balanced commercial diet for equine. To investigate a possible genetic cause, two foals from distinct bloodlines were brought to the stud. These also developed the deformities after 6 months.
Two of the affected foals were placed in a pasture away from the initial one and two others were admitted at the College of Veterinary Medicine in Lisbon. In those animals, except for one that had to be euthanized for humane reasons, an improvement was observed on their condition, with partial recovery of the deformity.
Histopathology was performed from (i) the tendon obtained by surgical desmotomy in one foal, (ii) tendon biopsies were performed in three foals and (iii) from the tissue of one foal during necropsy.
Histologically the most significant alterations were the dissociation of myofibrils of the smooth muscle. This was predominantly seen in the small intestine but also in the walls of small capillary vessels, including those of the tendon vasculature.
The flexural deformities have a complex and multifactorial etiopathogeny. They occur due to uncoupling of the longitudinal development of the bone and its adjacent soft tissues, but also from shortening of the tendon-muscle unit in response to pain.
In the case series presented here, there was no obvious cause for the development of this problem, therefore we hypothesized of this condition, especially those introduced in recent years.
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