Four more cases of canine influenza were reported in the Twin Cities on Wednesday by the Minnesota Board of Animal Health, leading to "strong indicators of community spread" of the rare virus after a larger outbreak earlier this month, the state agency said.

The Animal Humane Society closed its three shelters in Woodbury, Golden Valley and Coon Rapids on April 6, after about 200 dogs were infected with the highly contagious virus — the largest outbreak ever of canine influenza in Minnesota. The nonprofit has paused all pet adoptions through at least mid-May, its longest closure ever because of an animal-related outbreak, leading to an uptick in pets at other local shelters and nonprofit rescues.

Since then, the Board of Animal Health has been flooded with calls from veterinarians about suspected cases where testing wasn't done or was inconclusive. There are more cases of sick dogs than positive test results because the cost of testing is too expensive for many dog owners, Dr. Veronica Bartsch, senior veterinarian with the Board of Animal Health, said in a statement.

The four new cases are all in Hennepin County, according to the agency. Canine influenza causes similar symptoms as the flu in humans, including coughing and sneezing, a fever and runny nose, and dogs are sick and contagious for three to four weeks. The virus isn't transmittable to humans or most other animals.

The first outbreak of canine influenza was detected in the U.S. in 2015. But until this recent outbreak, Minnesota has had only minor reports of the virus in 2017, when 13 dogs were sick.

The Board of Animal Health recommends that dog owners avoid their dog having contact with other dogs, including at dog parks, and keeping their pet at home if they're sick. Dog boarding and day care facilities should separate symptomatic dogs and send any dog with signs of respiratory diseases home. To report a confirmed case of canine influenza or for more details on the virus, go to