Grooming and coat
What is a coat blow and how long does it last?
Last updated 23 September 2026 · How we write and check this
Short answer
A coat blow is when a double coated dog sheds its undercoat heavily to prepare for a new season, typically lasting two to four weeks and happening most noticeably in spring and again in autumn. Daily brushing during this period removes far more loose hair than the usual weekly routine.
What is actually happening
During a coat blow, large amounts of dead undercoat release at once rather than shedding gradually, which is why it feels dramatically different from the low level shedding a double coated dog does the rest of the year. The spring blow clears out the dense winter undercoat, while the autumn blow prepares the coat for colder weather ahead.
How long it typically runs
Most double coated dogs go through a coat blow lasting two to four weeks, though it can stretch closer to six weeks in dogs that are not brushed regularly during that time, since undercoat left in place takes longer to fully release.
Managing it well
Daily sessions with an undercoat rake, focused on the rear legs, tail, and flanks where the thickest undercoat sits, shorten how long the visible mess lasts and are more effective than any shampoo or supplement at managing a coat blow. A warm bath midway through can also loosen dead hair and make brushing easier afterward.
Key takeaways
- A coat blow is a heavy seasonal release of undercoat, typically lasting two to four weeks.
- It happens most noticeably in spring and autumn in double coated breeds.
- Daily brushing with an undercoat rake shortens the length of a visible coat blow.