VN February 2023

Vetnews | February 2023 37 5. Prep the patient: Can the procedure be done under sedation or GA? Shave the fur in the area if necessary. 6. Protect surrounding structures, especially the cornea. A very effective method is to break small pieces off from a polystyrene cup and wedge these under the eyelid in such a manner that the cornea is protected when a tarsal margin cryo procedure is being performed. Using a cryoprobe / fine spray tip type delivery system is better, as opposed to the diffuse cryospray units [purchased over the counter at pharmacies for controlling skin warts] that may not provide more control of the affected surface area being treated. 7. Surgically debulk if necessary After the freeze : After freezing, the lesion appears white due to the frozen water in the tissue. As the ice ball thaws, the area becomes erythematous and hyperaemic. A blister may form 2-24 hours after the freeze. Blisters may take several days to drain or dissolve. Once the blister breaks, a crust will form over the lesion, appearing more like fresh, healthy granulation tissue. The treated tissue, in essence, dies back, the crust forms, and one may even see some hypo-pigmented areas develop. After the dead tissue is sloughed off the lesion, it then becomes re-epithelized. This extends from the margins of the lesion and hair follicles. This process may take a few weeks. Our approach is to check the patient after about three weeks to monitor the progress, as well as to reassure the pet owner that the lesion is progressing as expected. In some cases, the post-treatment lesion may look ulcerated, which may be of concern to the owner. Healing occurs from 1-6 weeks, depending on the depth of freeze and size of the lesion. Mild ocular discharges may be noted, but amazingly, there seems to be good patient comfort, and progress seems uneventful in most cases. In general, a topical antibiotic eye drop is used post-op if the cryotherapy has been done along the tarsal margin or medial canthus regions. Oral NSAIDs are given for a few days. Tumour or mass selection : 1] Good candidates for cryo : Regulars I Ophthalmology Column >>> 38