Aytalā is the dual of ayṭal, referring to the two flanks or lower side regions of the animal. The gazelle comparison evokes a lean, agile, and proportionate body.
Sāqā naʿāmah contains the dual of sāq (“leg”), in an iḍāfah with “ostrich.” The ostrich supplies the image of long, powerful legs suited to swift running.
Neither image is a literal anatomical claim. The poet assembles selected strengths from different animals to convey the horse’s exceptional build.