Horses are the species most often abused, the Swedish Animal Welfare Agency said in its report, which it handed to the government.
A total of 209 cases of bestiality, of which 161 involved horses, have been documented since the 1970s, the agency said. It based its figures on responses to more than 1,600 questionnaires sent to veterinarians, animal welfare inspectors and police agencies across the country.
The government last year tasked the agency with determining the scope of the problem, which species are most often abused and whether the animals suffer psychologically from the abuse.
"Horses are most often subjected to violations. Even if it is difficult to assess an animal's degree of psychological suffering, it is likely that it experiences discomfort or is subjected to psychological suffering even in cases where there is no evidence of physical injury," the agency said.
"Some of the animals suffered injuries to their genitalia due to vaginal and anal penetration as well as cut and stab wounds," it said.
In the period 2000 to 2004, 119 cases of bestiality were documented, compared to just three known cases in the 1970s, 17 in the 1980s and 70 in the 1990s.
But the author of the report, Katarina Andersson, told AFP that the rise in documented cases did not necessarily mean that there was a de facto increase.
"We know that there must be cases that have not been documented," she said, adding that people have also become more aware of the problem in recent years and are therefore more likely to report suspected cases to the authorities.
Andersson said it was difficult to determine whether sex with animals was more common in Sweden than in other countries.
"It's impossible to say. We have not been able to find other studies from other countries because they haven't done extensive studies," she said.
Bestiality is not illegal in Sweden. A ban on the practice was lifted in 1944, along with a ban on homosexuality.
However, a person can be found guilty of cruelty to animals if prosecutors can prove that the animal suffered physical or psychological injury.
The Animal Welfare Agency said it considered the current legislation to be insufficient to protect animals from suffering, but stopped short of calling for a ban.