Yes, absolutely correct that the Sarama is a female dog even in Rg veda. Obviously by the reason that if she is instructed to find the cows then she is much listening( domesticated or on the verge of being domesticated. But unable to reconcile on Bhagvat's one interpretation that Sarama was a beast and mother of all the beasts.

( pl see https://web.archive.org/web/20100712011112/http://vedabase.net/sb/6/6/24-26/)

We do see the word and myth transforming into Shuna and thus finally we get Shunasira. The same element of sky, in the similar celestial longitude ( or a bit away) is transforming ( which was happening on earth in physical animal as well.