Revista Veterinaria Zacatecas 2010 - Universidad Autónoma de ...

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ABSTRACT
Aguilar-Faz, ME, Vázquez-Salinas S, Escobar-Medina FJ. Review of fractures in small animals and its
resolution. The skeleton gives to the organism structural support and allows its movements and locomotion.
In addition, it protects vital organs, keeps the mineral homeostasis and pH balance; allows the hematopoiesis
and acts like reservoir of growth factors and cytokines. In the canine specie, the skeleton is composed of 321
bones, all of them under the permanent risk of being fractured. This fact then makes important the study of
these bones. Any fracture reparation is conducted as equal as in embryologic bone development; where
osteoclast and osteoblast cells take part in this process in a coordinated way by means of molecular signals.
The osteoblast cells create the bone, produce and secrete the most abundant protein of the osseous matrix
(type I collagen) and later mineralize it. They also produce alkaline fosfatase and most of the non-colagen
proteins that constitute the matrix. The osteoblast may evolution to osteocytes, transform to inactive
osteoblast, stay like covering cells or undergo apoptosis. Like osteocytes, they take part of the mineralized
matrix in the ossification process. The osteoclast disolve the mineral and deteriorate the bone’s organic matrix
during the osseous renovation. In this process the organic matrix is eliminated in many sites in order to be
substituted by new tissue. Bone resorption is needed to many process of the skeleton particulary during bone
growth, facture resolution and maintenance of appropriate levels of Ca in blood circulation. The molecular
signals, like cytokines, transforming growth factor (TGF-) and angiogenic factors participate in fracture’s
resolutions. The cytokines begging the cascade of events (for its resolution) decrease the damage response by
recluting inflammatory cells, increase the extracellular matrix synthesis and simulate the angiogenesis. The
development of blood vessels is related with cartilage removal; therefore it is important for fracture
resolution. The vascular endothelial growth factor (VEGF) and angiopoietins take part in angiogenesis
development, both active during fracture resolution. The osteoblast cells express increased levels of VEGF,
and thercture, they are involved in the primary regulation of angiogenesis and fracture reparation.
Key words: osteoclast, osteoblast, osteocytes, cytokines. Veterinaria Zacatecas 2010; 3: 149-173
Keywords: Fractures, resolution, small animals
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