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  • Author or Editor: Celia L. M. Davenport x
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Abstract

Objective—To identify scintigraphic abnormalities in the pelvic region of horses examined because of hind limb lameness or poor performance and determine the clinical relevance of areas of abnormal radiopharmaceutical uptake (ARU) in these horses.

Design—Retrospective study.

Animals—128 horses.

Procedure—Medical records were reviewed, and information on signalment, history, admitting complaints, physical examination findings, and results of lameness examinations was recorded. Clinical relevance of areas of ARU was determined by comparison with results of other diagnostic tests. For horses with clinically relevant areas of ARU, follow-up information was obtained through telephone interviews with owners and trainers and analysis of race records.

Results—Areas of ARU were identified in the tuber coxae (25 horses), ischiatic tuber (9), hip joint (10), third trochanter (10), ilium (5), sacral tuber region (22), greater trochanter (1), cranial femoral cortex (1), skeletal muscle surrounding the pelvis (34), or multiple areas (11). In 44 horses, areas of ARU were associated with the primary cause of lameness; in 51, areas of ARU were not associated with the primary cause of lameness; and in 33, the primary cause of lameness was not determined. Thirty-six of the 44 horses with clinically relevant areas of ARU were available for follow-up; 15 (42%) had a good outcome.

Conclusions and Clinical Relevance—Results suggest that pelvic scintigraphy may be useful in identifying abnormalities in horses with hind limb lameness or poor performance. (J Am Vet Med Assoc 2004;224: 88–95)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To investigate the effects of enrofloxacin and magnesium deficiency on explants of equine articular cartilage.

Sample Population—Articular cartilage explants and cultured chondrocytes obtained from adult and neonatal horses.

Procedure—Full-thickness explants and cultured chondrocytes were incubated in complete or magnesium- deficient media containing enrofloxacin at concentrations of 0, 1, 5, 25, 100, and 500 µg/ml. Incorporation and release of sulfate 35S over 24 hours were used to assess glycosaminoglycan (GAG) synthesis and degradation. An assay that measured binding of dimethylmethylene blue dye was used to compare total GAG content between groups. Northern blots of RNA from cultured chondrocytes were probed with equine cDNA of aggrecan, type-II collagen, biglycan, decorin, link protein, matrix metalloproteinases 1, 3, and 13, and tissue inhibitor of metalloproteinase 1.

Results—A dose-dependent suppression of 35S incorporation was observed. In cartilage of neonates, 35S incorporation was substantially decreased at enrofloxacin concentrations of 25 mg/ml. In cartilage of adult horses, 35S incorporation was decreased only at enrofloxacin concentrations of ≥ 100 µg/ml. Magnesium deficiency caused suppression of 35S incorporation. Enrofloxacin or magnesium deficiency did not affect GAG degradation or endogenous GAG content. Specific effects of enrofloxacin on steadystate mRNA for the various genes were not observed.

Conclusion and Clinical Relevance—Enrofloxacin may have a detrimental effect on cartilage metabolism in horses, especially in neonates. (Am J Vet Res 2001;62:160–166)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the effects of insulin-like growth factor-II (IGF-II) on DNA and glycosaminoglycan (GAG) synthesis and the expression of matrix-related genes in equine articular cartilage explants and chondrocytes, respectively, with and without interleukin 1-β (IL1-β).

Sample Population—Articular cartilage from 12 adult horses.

Procedure—Articular cartilage was incubated in standard media with and without equine IL1-β (10 ng/mL) containing various concentrations of IGF-II for 72 hours. Synthesis of DNA and GAG was determined by incorporation of thymidine labeled with radioactive hydrogen (3H) and sulfate labeled with radioactive sulfur (35S), respectively. Total GAG content of the explants and spent media was determined by use of the 1,9-dimethylmethylene blue assay. Northern blots of RNA from cultured equine articular cartilage chondrocytes were hybridized with cDNA of major matrix molecules.

Results—Insulin-like growth factor-II stimulated DNA and GAG synthesis at concentrations of 25 and 50 ng/mL, respectively. In cartilage explants conditioned with IL1-β, IGF-II stimulated DNA and GAG synthesis at concentrations of 500 and 50 ng/mL, respectively. Insulin-like growth factor-II had no effect on total GAG content as determined by the 1,9-dimethylmethylene blue assay. No specific effects on steady-state levels of messenger RNAs were observed.

Conclusions and Clinical Relevance—Insulin-like growth factor-II stimulated DNA and GAG synthesis in equine adult cartilage and may have potential application in vivo. (Am J Vet Res 2004;65:238–244)

Full access
in American Journal of Veterinary Research