I had the same problem of wet dog smell after water getting into the cyclonic unit. There is only one way that I know of to get rid of the smell. You have to completely, and I stress completely disassemble the cyclonic unit and clean all parts that are part of the unit. I’ve done it twice but I will never do it again. There are no instructions on the procedure, but it is not that difficult but it’s time consuming. Figure about 6 hrs to disassemble, clean, dry and reassemble. I contacted Dyson but the response was unacceptable. Take it to a service center was there reply. I don’t believe you even have to get the unit wet to end up with wet dog smell. We have a dog that sheds a lot and looking at the base of the vacuum there were some darkened areas that confused me. I believe it’s a combination of the oil from the dogs hair and whatever dirt it comes in contact with. With that being said I did a little research and bought a cheap non hepa Bissell used vacuum to test my theory. After thoroughly cleaning the Dyson cyclonic unit and the rest of the vacuum I vacuumed with the Dyson first and then the cheap Bissell. The amount of dirt and dog hair that I removed from the Bissell was unbelievable. I could go on and on but this response is getting pretty long. I would gladly answer any questions if you have some.
Thanks
Paul