Complaints about dangerous dogs made to two councils in Norfolk have shown an increase during the past year.
Norfolk and Norwich University Hospital deals with animal bites
A hospital also said it had dealt with more people suffering from animal bites during the same period.
Breckland District Council's dog warden has seen a 50% rise in complaints about dangerous dogs, and South Norfolk is reporting a similar increase.
The Norfolk and Norwich University Hospital has dealt with 181 patients with dog bites compared to 106 in 2006.
Breckland dog warden Steve O'Brien said any dog was capable of turning nasty.
He said: "We're dealing with dangerous dog incidents that involve border collies, rotweillers and German shepherds but we know that any dog is capable of biting.
"Every incident is taken seriously to protect the public from these dogs, and if it is serious enough we will take the case to court which means the penalty can be anything from a fine to imprisonment with the dog being destroyed."
A spokesman for the Norfolk and Norwich Hospital said their staff dealt with 215 incidents of bites involving animals, predominantly dogs.