The musculoskeletal system consists of bones, muscles, tendons, ligaments, and articular structures that comprise the joint. The musculoskeletal system's primary functions include support of the body, provision of motion, and protection of vital organs.
Bones are also the primary storage organs for calcium and phosphorus and contain components critical to maintaining the hematopoietic system. Hematopoietic stem cells reside within the bone marrow, which is essential for producing blood cells and components of the immune system.
Diseases of the musculoskeletal system most often result in lameness, an abnormal stance or gait caused by pain, mechanical restrictions of the limbs, injury to one or more components of the musculoskeletal system, or neuromuscular disease. Although the underlying mechanisms of lameness can be interrelated, pain is the most common basis in all species.
In horses, dogs, and cats, musculoskeletal injuries are the most common source of debilitating pain, loss of athleticism, and (in horses) economic loss. Osteoarthritis is the most common orthopedic disorder diagnosed in middle-aged and older animals and has a substantial financial impact on owners of companion and performance animals.
In young performance horses, acute traumatic injuries are the most common cause of musculoskeletal dysfunction. Several studies demonstrate that problems involving the fetlock and carpal joints in horses account for most of the time lost from race training (1, 2, 3, 4). Tendon and ligament injuries are also common debilitating injuries in performance horses.
In dogs, cranial cruciate ligament rupture resulting in secondary osteoarthritis is a common musculoskeletal injury that leads to lameness.
Although they are less common causes of musculoskeletal system disorders, primary muscle diseases, neurological deficits, toxins, endocrinopathies, metabolic disorders, infectious diseases, blood and vascular disorders, nutritional imbalances or deficits, and congenital disabilities can also adversely affect the musculoskeletal system.
For More Information
Cole R, Hespel A-M. Overview of the musculoskeletal system. In: Holland M, Hudson J, eds. Feline Diagnostic Imaging. John Wiley & Sons; 2020:579-619.
Johnson MD, Gillick MS, Fox SM. Musculoskeletal disorders and injuries. In: Schaer M, Gaschen F, Walton S, eds. Clinical Medicine of the Dog and Cat. 4th ed. CRC Press; 2023:603-646.
van Weeren PR, Back W. Musculoskeletal disease in aged horses and its management. Vet Clin North Am Equine Pract. 2016;32(2):229-247.
Also see pet owner content regarding components of the musculoskeletal system in dogs, cats, and horses.
References
Paris A, Beccati F, Pepe M. Type, prevalence, and risk factors for the development of orthopedic injuries in endurance horses during training and competition. J Am Vet Med Assoc. 2021;258(10):1109-1118. doi:10.2460/javma.258.10.1109
Sarrafian TL, Case JT, Kinde H, et al. Fatal musculoskeletal injuries of Quarter Horse racehorses: 314 cases (1990–2007). J Am Vet Med Assoc 2012;241(7):935-942. doi:10.2460/javma.241.7.935
Crawford KL, Finnane A, Greer RM, et al. Appraising the welfare of Thoroughbred racehorses in training in Queensland, Australia: the incidence and type of musculoskeletal injuries vary between two-year-old and older Thoroughbred racehorses. Animals (Basel). 2020;10(11):2046. doi:10.3390/ani10112046
Reed SR, Jackson BF, McIlwraith CW, et al. Descriptive epidemiology of joint injuries in Thoroughbred racehorses in training. Equine Vet J. 2012;44(1):13-19. doi:10.1111/j.2042-3306.2010.00352.x
