Eighteen cases of COR were identified, all diagnosed in an 8-year period (2006–2014).
Affected dogs were typically young (range 1–8; median 2 years), and both sexes were equally represented.
Common clinical signs included exophthalmos (16/18) with dorsolateral deviation of the globe (10/18) and elevation of the nictitans (12/18).
Ultrasonography, performed in nine cases, revealed an orbital mass with mixed echogenicity and posterior globe indentation.
Advanced imaging, performed in nine cases, demonstrated a soft tissue mass with variable contrast enhancement and lysis of the orbital bones (5/9).
Histologically, all tumors were subclassified as embryonal rhabdomyosarcoma.
All neoplasms demonstrated positive immunohistochemical labeling for desmin, and 14/18 were positive for skeletal muscle actin.
Follow-up information was available for 15/18 cases.
Older dogs, aged 6–8 years, had no clinical signs of recurrence or metastasis 8–13 months postdiagnosis (4/4).
Most younger dogs (9/11), aged 1–4 years, were euthanized within 6 months (median 2.5 months) of diagnosis due to recurrence at the surgical site (5/9) and/or metastasis (5/9).
Source: Scott, E. M., Teixeira, L. B.C., Flanders, D. J., Dubielzig, R. R. and McLellan, G. J. (2015), Canine orbital rhabdomyosarcoma: a report of 18 cases. Veterinary Ophthalmology. doi: 10.1111/vop.12270
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