Sky Sports understands a number of clubs are tracking highly-rated Carlisle United midfielder Brad Potts.
Sheffield United are planning to send Andy Butler back out on loan after seeing an agreement with Walsall collapse.
Kiernan had a temporary spell at Griffin Park in November, making seven appearances for Uwe Rosler's side before returning to the Latics.
The Republic of Ireland Under-21 international featured in both central defence and midfield and played a key role in Brentford's win over Sheffield United in late November, helping to set up the first goal.
He is available for selection for the Bees' League One game at Oldham on Saturday.