Long-Term Effects of Various Therapies for Pigmentary Keratitis in Pugs

To compare the long-term efficacy of simplified medial canthoplasty (MCP) with and without adjunctive corneal cryotherapy (CC), followed by topical therapy (TT), versus TT alone in the management of pigmentary keratitis (PK) in Pugs.

Medical records of Pugs diagnosed with PK were retrospectively reviewed and assigned to four treatment groups. Only dogs with a minimum follow-up period of 1.5 years were included. Group 1 received TT alone; Group 2 underwent MCP with TT. Group 3 was treated with MCP, bilateral CC, and TT, while Group 4 received MCP, TT, and randomized unilateral CC. Outcome measures included ocular discharge, Schirmer tear test-1 (STT-1), fluorescein staining (FS), and corneal pigmentation (density and distribution), assessed at baseline and at final follow-up.

Seventy-six Pugs met the inclusion criteria. Tear film parameters (STT-1, FS, and ocular discharge) improved in all dogs following therapy. In Groups 1 and 2, regression of the PK occurred in approximately 25% of dogs. In Group 2, complete resolution of the PK was observed in two dogs. In Group 3, corneal pigmentation decreased or remained stable in most cases, and in Group 4, PK consistently regressed in CC-treated eyes.

Simplified MCP in combination with TT provides superior long-term control of PK compared with TT alone. In dogs presenting with advanced pigmentation, adjunctive CC offers additional therapeutic benefit, although partial recurrence of pigmentation may develop over time.