Bhashya
ते श्वान तत्रैव आगत्य ऋषे समक्षं यथैवेह कर्मणि बहिष्पवमानेन स्तोत्रेण स्तोष्यमाणा उद्गातृपुरुषा सरब्धा संलग्ना अन्योन्यमेव सर्पन्ति, एवं मुखेनान्योन्यस्य पुच्छं गृहीत्वाआससृपु आसृप्तवन्तः, परिभ्रमणं कृतवन्त इत्यर्थः, त एव ससृप्य समुपविश्य उपविष्टाः सन्तः हि चक्रुः हिंकारं कृतवन्तः ॥
In plain words
Those dogs came right before the seer and—just as priests performing the outer pavamāna stotra move along linked together in sacrifice—each holding the tail of the one ahead in its mouth, they moved in a circle. Having completed this movement and seated themselves together, they uttered the sacred hiṃkāra chant.
Close to the Sanskrit
Those dogs having arrived right there in the presence of the seer, just as here in ritual with the outer pavamāna stotra the udgātṛ priests linked together crawl one after another, so taking each other's tail with the mouth they crawled, having made circumambulation that is the meaning, those having crawled having sat down seated [thus] made the hiṃkāra sound.