CANINE AND FELINE KERATOMALACIA TREATED WITH CO2 LASER Ana Calado Lopes 1 , Luís Filipe Carvalho 2 1 – Escola Universitária Vasco da Gama, Av. José R. Sousa Fernandes 197, Lordemão, 3020-210 Coimbra. 2 – Hospital Veterinário da Marinha Grande, R. Dom João Pereira Venâncio 7, 2430-291 Marinha Grande. Introduction - Canine and feline keratomalacia is a painful and rapidly progressive corneal disease of infectious or non-infectious origin (Ion, Lonascu, & Birtoiu, 2015) whose medical and surgical management have unreliable outcomes (Kokuti, 2019, Ion et al., 2015). Highly precision CO 2 laser surgery in keratomalacia patients is an innovative and poorly documented method, not fully consensual, that enables damaged cells vaporization with minor inflammatory onset (Gilmour, 2003). Materials and Methods - Laser surgery consisted of CO 2 laser excimer 2 W (power range), repeat pulse mode of 10Hz, 5 msec, 5%, size tip of 0,4 mm, focused at 1 to 3 mm from the selected tissue, until its vaporization. A third eyelid-scleral pexia was placed over two weeks. Support treatment with topical tobramycin, artificial tears QID and pain relief (cats - meloxicam 0,1mg/Kg SID; dogs carprofen 4mg/Kg SID, PO) were administered for three days. After suture removal cornea was clinically controlled. Results - All animals recovered from keratomalacia after third eyelid suture removal. Corneal regeneration and transparency was almost completely achieved in dogs (Figure 1) over 20,37 days +/-8,7 days and in cats over 24,0 days +/-6,1 days. Both keratomalacia and mild associated edema (Figure 2) and chronic keratitis with collagenolysis (Figure 3) fully recovered. Figure 1 – Canine right keratomalacia. A) Fluorescein positive area is identified (red line) before CO 2 laser surgery and associated corneal edema is noticed. B) Two-week post- surgical control exhibits transparent cornea with mild scar tissue. Figure 2 – Canine left keratomalacia. A) Fluorescein positive area is identified (red line) before CO 2 laser surgery with mild associated corneal edema. B) Two-week post- surgical control exhibits healthy and regular transparent cornea. Objective - This study aims to evaluate the treatment outcome of CO 2 laser in 25 animals, 19 dogs (mean age of 6,2 years +/- 5,1 years) and 6 cats (mean age of 6,5 years +/- 6,1 years) with keratomalacia of unknown etiology and variable severity, size, duration and deepness. Figure 3 – A) Canine left eye chronic keratitis with axial granulation tissue surrounded by collagenolytic tissue. B) Post-surgical healthy and regular transparent cornea, two weeks after CO 2 laser treatment. Discussion – CO 2 laser surgery is able to promote keratomalacia fully recovery, preserving healthy tissues, due to damaged cells ablation by vaporization, minimizing inflammatory response. This outcome is independent on ulcer etiology and severity, patient age and preexistent underlying diseases. Bibliography Gilmour, M. A. (2003). Laser applications for corneal disease. Clin Tech Small Anim Pract, 18 (3), 199-202. doi:10.1016/s1096-2867(03)90017-x Ion, L., Lonascu, L., & Birtoiu, A. (2015). Melting keratitis in dogs and cats. Agriculture and Agricultural Science Procedia, 6 , 342 – 349 Kokuti, R. (2019). Medical treatment of keratomalacia in a cat. Veterinary Record Case Reports, 7: e000820 . doi:doi: 10.1136/vetreccr-2019-000820 McGavin, M. D. Z., J. F. (2017). The eye. In Elsevier (Ed.), Pathologic Basis of Veterinary Disease (6 ed., pp. 1265). St. Louis. A B A B A B Bacteria Protease inhibitors Proteolytic enzymes Neutrophils Conclusion – CO 2 laser surgery is a highly satisfactory safe and consistent method to treat keratomalacia of unknown origin in canine and feline patients of all ages. Acknowledgments - We thank to Dr. Pedro Tralhão for his contribution to this work. Keratomalacia