Humane Endpoint: Example from a Murine Model of Disseminated Sporotrichosis

Vertebrate animal models are essential in research; however, efforts need to be made to decrease animal suffering as much as possible. It could be useful to determine humane endpoints that could serve as surrogates for a fatal outcome. We address this issue with respect to infectious diseases. We propose a humane endpoint for studies of Sporothrix brasiliensis infection. BALB/c mice were inoculated subcutaneously in the footpad. To define a humane endpoint, we considered two groups: animals who died during the experiment, and those euthanized at the end of the experiment. The groups were compared for colony-forming units (CFU) in internal organs, clinical condition, and body weight. Thirteen (22%) animals died before the end of the experiment due to the progression of local infection to severe and disseminated sporotrichosis. Analyzing data of the groups, we propose the following future criteria for euthanasia as a humane endpoint: neurological impairment OR necrosis of the footpad OR loss of ≥ 20% body weight AND moderate to severe dehydration. In view of the current global epidemiological impact of zoonotic sporotrichosis caused by S. brasiliensis, our data could facilitate the utility of models used to study the disease, particularly therapy.