Musculoskeletal Disease & Injuries

Photo: Silicosis Associated Osteoporosis (SAO)

Horse with silicate associated osteoporosis. Note the prominent shoulder blades (arrow) and sway back.

Silicosis Associated Osteoporosis (SAO)


We are investigating a recently identified disease in horses in which the bones become weak and osteoporotic. Research is focused on 1) determining what happens to the bones on microscopic level and 2) identifying the underlying mechanism of the disease. The ultimate goal of the research is to find optimal management of the affected horses and prevention strategies. Because many of the horses with the bone disease also have a lung disease called pulmonary silicosis, we are pursuing understanding of the link between the lung disease and the bone disease. 

Dr. Mandy Murray Arens has greatly advanced our understanding of SAO through her remarkable work and has completed her PhD in 2011. Dr. Regina Zavodovskaya, with interest is bone pathology, presently continues the investigation of SAO.


Regina Zavodovskaya, MS, DVM, Dipl ACVP
Postdoctoral Researcher
Phone: 530-754-0156 (office)

Susan M. Stover, DVM, PhD, Dipl ACVS
Phone: 530-752-7435 (office)

You can help with the study by making us aware of horses whose disease warrants humane euthanasia due to poor quality of life because of SAO, or other terminal conditions. Donated horses will be humanely euthanized in the large animal clinic. For more details please contact Dr. Zavodovskaya via email, or the phone number listed above.


Anderson J, Galuppo, L., Barr, B., Puchalski, S., MacDonald, M., Magdesian,G, Stover, SM.: Scintigraphic findings and clinical characterization of a bone fragility disorder in horses: 16 cases (1980-2006). Journal of American Veterinary Medical Association 232: 1694-1699, 2008

Durham M, Armstrong, CM: Fractures and Bone Deformities in 18 horses with Silicosis. Proceedings of the 52nd Annual Convention of the American Association of Equine Practitioners, San Antonio, Texas, USA, 2-6 December, 2006. 311-317

Arens AM, Puchalski SM, Whitcomb MB, Bell R, Gardner IA, Stover SM. Comparison of scapular ultrasound, physical examination and serum biomarkers for detection of equine bone fragility syndrome. J Am Vet Med Assoc. 2013. 242(1): 76-85.

Symons JE, Entwistle RC, Arens AM, Garcia TC, Christiansen BA, Fyhrie DP, Stover SM. Mechanical and Morphologic Properties of Trabecular Bone from Horses with a Bone Fragility Syndrome. Am. J. of Vet Res. 2012, 73(11): 1742-1751

Katzman SA, Nieto JA, Arens AM, MacDonald MH, Puchalski SM, Galuppo LD, Snyder JR, Maher O, Bell, RJ. Zolerdonate for the treatment of equine bone fragility disorder: 10 cases. J of Am Vet Med Assoc. 2012.240(11): 1323-1328.

Arens AM, Puchalski SM, Whitcomb MB, Bell R, Gardner IA, Stover SM. Abstract: Bone fragility syndrome: comparison of scintigraphy, physical examination, scapular ultrasound, and serum markers of bone turnover for accuracy in diagnosis. 57th Annual Convention of American Association of Equine Practitioners, San Antonio, Texas, USA. 2011. Proceedings of the AAEP Annual Convention, San Antonio TX. USA November 8 – 22, 2011.457-458.

Arens AM, Barr B, Poppenga R, Puchalski S, Kulin R, Anderson J, Stover S. Osteoporosis associated with pulmonary silicosis in an equine bone fragility syndrome. Vet Pathol. 2011. 48(3): 593 – 615.

Murray AL, Anderson JA, Stover, SM. Diagnostic, pathological, and radiographic findings in equine bone fragility syndrome. Abstract: 54th Annual Convention of the American Association of Equine Practitioners, San Diego, California, USA, 269-270. 2008