Yes, it should work fine on your Rott.

Seresto has been extensively tested for its safety, including pets chewing on the collar or ingesting the entire collar. As the vast majority of active ingredients are bound in the collar matrix and not on the surface, the only side effect recorded after ingesting a full collar was a mild stomach upset (e.g. loose stools), which was resolved within 24 hours. To prevent your pet from chewing the collar again, you might want to reattach it slightly more tightly.

Yes, Seresto should work on your chow chow.

Seresto Large Dogs is 27.5 inch long.

Seresto has been extensively tested for its safety, including pets chewing on the collar or ingesting the entire collar. As the vast majority of active ingredients are bound in the collar matrix and not on the surface, the only side effect recorded after ingesting a full collar was a mild stomach upset (e.g. loose stools), which was resolved within 24 hours.