Multifocal discrete osteolysis in a horse with silicate associated osteoporosis.
Abstract: Silicate associated osteoporosis (SAO) was diagnosed in an adult horse with the shortest documented exposure to cytotoxic silicates of 2 years. The horse was evaluated for a 6-months history of progressive back tenderness and acute onset of lameness. The horse had a marked (4/5) [American Association of Equine Practitioners scale] left forelimb lameness, moderate (2/5) hindlimb ataxia and weakness, and cervical pain upon palpation. Physical examination did not reveal clinical skeletal deformities or respiratory compromise. Radiographs revealed widespread, discrete, sharply delineated, osteolytic lesions in the skull, vertebral column, ribs, scapulae and middle phalanx (P2) of the left forelimb and a diffuse bronchointerstitial lung pattern. The presumptive clinical diagnosis was widespread, metastatic osteolytic neoplasia. Due to the poor quality of life and grave prognosis, the horse was humanely euthanised. Post mortem examination revealed pulmonary silicosis in the lungs and hilar lymph nodes and osteolytic lesions with numerous, large osteoclasts and disorganised bone remodeling both consistent with SAO. SAO should be included as a differential diagnosis for horses with widespread, multifocal, discrete osteolysis and history of exposure to endemic regions with possible cytotoxic silicate inhalation. Exposure time of 2 years is potentially sufficient to develop SAO.
Publication Date: 2018-02-15 PubMed ID: 33041530PubMed Central: PMC7546327DOI: 10.1111/eve.12899Google Scholar: Lookup
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Summary
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This study presents the case of an adult horse diagnosed with Silicate-associated Osteoporosis (SAO) after a two-year exposure to cytotoxic silicates. The horse showed symptoms like back tenderness, lameness, hindlimb ataxia and weakness, and cervical pain. Radiographs identified osteolytic lesions in several parts of the horse’s body. Ultimately, due to its deteriorating condition, the horse was euthanized. The necropsy confirmed the presence of SAO and the study concludes that exposure to cytotoxic silicates even for limited periods like two years can lead to the development of SAO in horses.
Overview of the Case
- This research revolves around a symptomatic horse which underwent several tests for a period of six months due to progressive back tenderness and sudden onset of lameness. The horse was also observed to have a significant left forelimb lameness, mild hindlimb weakness, and pain in the neck region. This indicated a grave condition which led to further investigation.
Investigation and Diagnosis
- Physical examination did not show any obvious skeletal deformities or respiratory issues in the horse. However, when radiographs were taken, numerous osteolytic lesions were discovered in the skull, vertebral columns, ribs, shoulder blades, and in the long bone of the left forelimb.
- Additionally, a diffuse pattern was observed in the horse’s lungs, which led to the preliminary clinical diagnosis of widespread, metastatic osteolytic neoplasia. This is a serious bone disease causing bone loss, commonly seen in cancer patients.
Post Mortem Evaluation
- Given the poor quality of life and grim prognosis, the decision was made to euthanize the horse. Post-mortem analysis allowed for a more conclusive diagnosis.
- The necropsy results revealed Pulmonary Silicosis in both the lungs of the horse and its hilar lymph nodes, a condition usually caused by the inhalation of dust containing silica.
- The bone lesions exhibited a large number of osteoclasts and signs of disorganized bone remodeling. These findings corresponded to a condition known as Silicate-associated Osteoporosis (SAO), confirming the diagnosis.
Conclusion
- The study concludes that SAO should be considered when diagnosing horses exhibiting widespread, multifocal, and discrete osteolysis, especially if they have been exposed to areas endemic with potentially cytotoxic silicate dust.
- It is also highlighted that exposure duration as short as two years could also potentially lead to the development of SAO.
Cite This Article
APA
Zavodovskaya R, Eckert M, Murphy BG, Stover SM, Kol A, Diab S.
(2018).
Multifocal discrete osteolysis in a horse with silicate associated osteoporosis.
Equine Vet Educ, 31(10), 517-522.
https://doi.org/10.1111/eve.12899 Publication
Researcher Affiliations
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616 USA.
- Steinbeck Country Equine Clinic, Salinas, CA 93908 USA.
- Department Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616 USA.
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616 USA.
- Department Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616 USA.
- California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California-Davis, Davis CA 95616 USA.
Grant Funding
- T32 OD011147 / NIH HHS
Conflict of Interest Statement
Authors’ declaration of interests The authors declare that there were no conflicts of interest.
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