Dogs may cause urinary tract infections (UTIs), such as cystitis, new research suggests.

As The Daily Mail reports, two patients receiving hospital treatment for the condition carried the same infection-causing bacteria that was found in their dogs' faeces, a study found.

Although one of the patients had recovered after almost a year, their dog still harboured the bacteria, which suggests it is a permanent carrier and transmitted the infection to its owner, according to the researchers.

It is unclear how dogs may infect their owners with UTIs. Nonetheless, study author Dr Peter Damborg, from the University of Copenhagen, urges pet owners to avoid being licked by their animals, particularly if they have weak immune systems.

UTIs affect many women at some point in their lives and are usually caused by bacteria entering their urinary tracts from their bowels, which can occur during sex. 

Dr Damborg told the New Scientist: 'I think that people in general should take precautions when in contact with their pets.

'If someone has a compromised immune system, then this point is even more important as they are more at risk for infections.'

Such people may include those undergoing chemotherapy or organ transplants. 

Dr Damborg adds that although none of the study's participants appeared to catch infections from their cats, this could theoretically occur. 

The researchers analysed 119 patients being treated at Hvidovre Hospital, Copenhagen, for a UTI, of which 19 lived with either cats or dogs.

The pet owners swabbed their animals' faeces at the start of the study and again 10 months later. 

The findings were published in the journal bioRxiv.