HARTFORD • A little girl in the United States with an inoperable brain tumour and a huge love for dogs received a special surprise last week.

About 40 police officers and dogs from the Hartford police department's K-9 unit were seen queueing up outside a house in Hartford, Wisconsin, last Saturday.

They had stopped by to surprise seven-year-old Emma Mertens, whose family had asked on social media for pictures of dogs to cheer her up.

Emma was diagnosed with diffuse intrinsic pontine glioma in January and has since undergone radiation therapy and surgery to reduce swelling on her brain.

The avid dog lover was overjoyed by the furry surprise, and pictures online showed her smiling and patting the dogs.

On Team Emma - Emmalovesdogs7, a Facebook page set up for her, one post said: "There are no words... Pure joy! Thank you to everyone who took the time to organise and participate in this. Emma is still all smiles! Over 35 different departments and many more K-9s and officers."

A post on the Wisconsin Humane Society's Facebook page on Feb 28 had asked users to post photos of dogs in the comments section for Emma to look at.

The post has since garnered almost 180,000 comments, featuring adorable pictures of all types of dogs, and even the occasional cat.

The amount of dog pictures the family has received has also been overwhelming, said a post on the Team Emma Facebook page.

The family had received so many pictures through regular mail and e-mail that they set up the Facebook page to channel all the pictures there instead.

The Lincoln County Sheriff's Office in Wisconsin also posted on its Facebook page a letter to Emma from two of its K-9 dogs named Nina and Poncho.

The letter was signed with both names written in a shaky scrawl, accompanied by a paw print from each dog.