Histochemical and morphometric evaluation of skeletal muscle from horses with exertional rhabdomyolysis (tying-up).
Abstract: Thirteen horses with histories of exertional rhabdomyolysis were exercised for 20 minutes to induce clinical signs of lameness, elevated serum creatine kinase (CK), and aspartate aminotransferase (AST) activities and skeletal muscle morphologic lesions. The clinical signs exhibited by affected horses included trembling, sweating, increased rate of respiration, and restricted limb movement. Serum CK reached maximal activity between 4 and 8 hours after the exercise period and serum AST activity peaked between 24 and 48 hours. Histologically, the skeletal muscle lesions in muscle biopsies 24 hours after the exercise period consisted of segmental muscle fiber degeneration. Damaged muscle fibers were repaired by myoblastic regeneration. Horses with moderate (greater than 1,500 U/liter) to severe (greater than 5,000 U/liter) elevations of serum CK activity accompanied by clinical signs of muscle soreness induced by exercise, had visible muscle fiber degeneration microscopically. Frozen sections of biopsies of the gluteus medius muscle from affected (n = 13) and control (n = 11) groups of horses were processed to demonstrate myofibrillar ATPase activity. These sections were then used to determine fiber types, area percentages, and mean cross sectional fiber sizes. The mean type I, type II, and intermediate fiber sizes were significantly larger in the affected group than in the control group. In the gluteus medius muscles of the affected group, there was a significantly greater percentage of intermediate fibers and a significantly greater percentage of area occupied by intermediate fibers than in the control group. In the muscle samples with acute lesions of exertional rhabdomyolysis, type II fibers were selectively but not exclusively affected. In one horse which was subsequently necropsied 24 hours after the exercise period, lesions were present in several postural muscles, the masseter muscle and the heart. We conclude that the gluteus medius muscle fibers of affected horses are larger in cross sectional area than those of control horses and that there is preferential degeneration of type II fibers in acute lesions of exertional rhabdomyolysis.
Publication Date: 1986-07-01 PubMed ID: 2944276DOI: 10.1177/030098588602300409Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the effects of exertional rhabdomyolysis, a muscle degenerative condition, on horses. Researchers triggered the condition in 13 horses and compared skeletal muscle samples from affected and control groups to determine the disease’s histochemical and morphometric impacts.
Research Procedures
- The experiment began by deliberately inducing exertional rhabdomyolysis in thirteen horses that had prior histories of the condition. Researchers triggered by the disease by having the animals exercise for 20 minutes.
- The induced exertional rhabdomyolysis exhibited clinical symptoms such as lameness, trembling, increased respiration rates, and hampered limb movement. Affected horses’ serum also showed elevated levels of creatine kinase (CK) and aspartate aminotransferase (AST), and evidence of morphologic muscle lesions.
- CK levels peaked between 4 and 8 hours post-exercise while AST levels peaked between 24 and 48 hours. Histological analysis of the skeletal muscles revealed segmental muscle fiber degeneration 24 hours after the exercise period.
Findings from Muscle Analysis
- Damaged muscle fibers repaired through myoblastic regeneration. Horses with moderate to severe CK activity elevation (greater than 1,500 U/liter to greater than 5,000 U/liter) and clinical muscle soreness evidence demonstrated visible muscle fiber degeneration under microscopy.
- Biopsy samples from both affected and control horse groups were processed to indicate myofibrillar ATPase activity, which was used to determine fiber types, area percentages, and mean cross-sectional fiber sizes.
- Horses in the affected group had significantly larger type I, II, and intermediate fibers compared to the control group. Additionally, the affected horses displayed a greater percentage of intermediate fibers and a higher area occupied by these intermediate fibers.
- Type II fibers were primarily, though not exclusively, impacted in muscle samples with acute exertional rhabdomyolysis lesions.
Other Observations and Conclusion
- In one horse necropsied 24 hours after exercise, lesions were found in several postural muscles, the masseter muscle, and the heart. This finding suggests a widespread impact of the disease within the horse’s system.
- The researchers concluded that horses affected by exertional rhabdomyolysis have larger cross-sectional gluteus medius muscle fibers than horses without the condition. It was also found that acute exertional rhabdomyolysis lesions favorably deteriorate type II fibers.
This research furthers the understanding of exertional rhabdomyolysis in horses, particularly regarding how the disease affects the histochemical and morphometric aspects of skeletal muscles. The findings might support future investigations and therapies targeting this muscle condition in horses.
Cite This Article
APA
McEwen SA, Hulland TJ.
(1986).
Histochemical and morphometric evaluation of skeletal muscle from horses with exertional rhabdomyolysis (tying-up).
Vet Pathol, 23(4), 400-410.
https://doi.org/10.1177/030098588602300409 Publication
Researcher Affiliations
MeSH Terms
- Adenosine Triphosphatases / analysis
- Animals
- Aspartate Aminotransferases / blood
- Creatine Kinase / blood
- Female
- Horse Diseases / metabolism
- Horse Diseases / pathology
- Horses
- Lameness, Animal / metabolism
- Lameness, Animal / pathology
- Male
- Muscles / metabolism
- Muscles / pathology
- Physical Exertion
- Rhabdomyolysis / metabolism
- Rhabdomyolysis / pathology
- Rhabdomyolysis / veterinary
Citations
This article has been cited 6 times.- James C, Lloyd EM, Arthur PG. The Level of Thiol-Oxidised Plasma Albumin Is Elevated Following a Race in Australian Thoroughbred Horses. Vet Med Sci 2025 Jul;11(4):e70487.
- Buckley P, Buckley DJ, Freire R, Hughes KJ. Pre-race and race management impacts serum muscle enzyme activity in Australian endurance horses. Equine Vet J 2022 Sep;54(5):895-904.
- Isaacs AW, Macaluso F, Smith C, Myburgh KH. C-Reactive Protein Is Elevated Only in High Creatine Kinase Responders to Muscle Damaging Exercise. Front Physiol 2019;10:86.
- Ememe MU, Abdullahi US, Sackey AK, Ayo JO, Mshelia WP, Edeh RE. Effects of a joint supplement whose main components are resveratrol and hyaluronic acid on some biochemical parameters in aged lame horses. J Equine Sci 2016;27(1):19-22.
- Sierra E, Fernández A, Espinosa de los Monteros A, Arbelo M, Díaz-Delgado J, Andrada M, Herráez P. Histopathological muscle findings may be essential for a definitive diagnosis of suspected sharp trauma associated with ship strikes in stranded cetaceans. PLoS One 2014;9(2):e88780.
- Amelink GJ, Kamp HH, Bär PR. Creatine kinase isoenzyme profiles after exercise in the rat: sex-linked differences in leakage of CK-MM. Pflugers Arch 1988 Sep;412(4):417-21.
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