Along with the health benefits associated with less stress and anxiety, therapy dogs bring joy and comfort to hospital patients. Unfortunately, they can also bring methicillin-resistant Staphylococcus aureus (MRSA), a bacterium that causes infections and is resistant to common antibiotics. MRSA carriage does not generally lead to infection in healthy people, but the risk is much greater in vulnerable patients, such as children with cancer. Because the dogs typically interact with patients both one-on-one and in group visits, in multiple departments or hospitals, the risk of MRSA carriage is high.

A study at Johns Hopkins Bloomberg Children's Hospital tested a cleaning procedure on specially trained dogs that engage with young cancer patients during outpatient visits. The results suggest that the simple treatment, which consists of cleaning each dog with antibiotic chlorohexidine shampoo at the start of the day and following up with chlorohexidine wipes every five to ten minutes, reduces the spread of MRSA to the young patients who visit and play with the therapy dogs.

The process of ridding the dogs of the bug is known as decolonization. The study tested 45 cancer patients, ages 2 to 20, with seven control sessions in which the dogs were not decolonized and six intervention sessions. No patients with active MRSA infections were included. In the control sessions, four patients (15.4%) and three dogs (42.9%) became MRSA carriers, compared with one patient (4.5%) and two dogs (33.3%) in the sessions with the treated dogs.

"This intervention not only decreases MRSA transmission from the therapy dog to the patient, but also indirectly between patients or from the hospital environment to patients, with the dog as an intermediary," said Kathryn Dalton, veterinarian and a Ph.D candidate in the department of environmental health and engineering at Johns Hopkins University Bloomberg School of Public Health, Baltimore. "Decolonization is inexpensive and fast — it can be done by hospital staff or even the dog handler — and improves patients' and dogs' safety."

The study was presented at IDWeek 2018.