The authors observed the anterior segment changes following recti tenotomy in 34 adult dog eyes. 16 eyes with tenotomy of any 2 recti showed no discernible signs of anterior segment ischemia (ASI). 18 eyes had tenotomy of 3 recti in various combinations, and 5 of 9 eyes (55.6%) with tenotomy of superior, inferior and lateral recti manifested serious ASI. The pathological characteristics of ASI were degeneration, necrosis and exfoliation of epithelial cells, inflammation of anterior segment tissues and cell membrane structural damages. The authors pointed out that simultaneous tenotomy of superior, inferior and lateral recti should be avoided in clinical practice because of the high risk of ASI.