u/Kit-Kat1523

We've just taken in Buddy from a family member who couldn't keep him due to health and new housing. He was groomed professionally at the beginning of July on his way here. What do i need to keep his coat mai stained between groomings? He moved from a hot dry climate to a cooler humid climate so he seems to be having an undercoat turnover.

We currently have a slicker brush and one of those metal cushioned brushes but they don't seem to get enough of the trapped undercoat.