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Ocular tumours are seldom described in veterinary patients. According to Veterinary Medical Database these lesions affect only 0.87 and 0.34% of all dogs and cats, respectively. However, it seems that they are more common, especially benign tumours, and are not histologically examined. Ocular neoplasia is second to glaucoma as the cause for enucleation surgery and tumours cause 25% of nontraumatic uveitis in dogs. Primary ocular tumors may develop from eyelids and adnexa, from optic nerve, or may form within the globe. The most common canine peri-ocular neoplasm is Meibomian adenoma and followed by melanocytoma. Other mesenchymal tumours are described much less often. Irrespectively to the tumour mass lesions, other clinical signs of some neoplasms of the eyelids, third eyelid, and ocular surface may not be seen. Abnormalities often described include epiphora, mucopurulent discharge, protrusion of the third eyelid and corneal/conjunctival ulceration. Common clinical signs of intraocular neoplasms include a visible intraocular or scleral mass, glaucoma, hyphema and uveitis with no or only minor pain. Intraocular lesions may be incidentally found during ophtalmoscopic examination. Usually the clinical and ultrasonographic appearance is strongly suggestive of intraocular neoplasia, although the definitive diagnosis may be impossible without invading the eye or removing the globe. Diagnostic workup, in cases of finding intraocular mass, includes careful physical examination, ophtalmoscopic examination, visualization techniques (skull and thoracic radiographs, ultrasonography, computed tomography) and cytology of the removed lesion and regional lymph nodes. In some cases, especially when benign tumour is suspected, animals are carefully observed and regular control examinations are performed. When malignant tumors are suspected or if complications such as intractable uveitis or secondary glaucoma develop, surgery is required. Ocular enucleation or exenteration is the treatment of choice in most malignant or/and progressive benign eye tumors. In cases of orbital involvement orbitectomy can be performed. Prognosis depends upon the tumour type, extension of the process and therapeutic modalities used but in many, even malignant cases, can be good.
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