Histochemical study of the anulus fibrosus in normal canine caudal cervical intervertebral discs

A qualitative assessment of glycosaminoglycans (GAGs) in the non-chondrodystrophoid canine cervical anulus fibrosus was performed using the Alcian blue/critical electrolyte concentration staining technique. Estimates of GAG concentration were deduced for two groups of dogs (average age four and eight years) by determining the hyaluronic acid, chondroitin sulphates and keratan sulphate 'alcianophilic indices'. Keratan sulphate was the predominant GAG in the four-year-old group of dogs. The concentration of keratan sulphate was equal to that of chondroitin sulphates in the eight-year-old group and the total GAG concentration was decreased. This qualitative assessment indicated that the concentrations of keratan sulphate decreased and chondroitin sulphates increased between four and eight years of age. Similar conclusions have not been reported for anuli in the thoracic and lumbar regions of the canine spine.