A physiological condition determination system and method can include: attaching a tag to animal tissue; emitting light into the animal tissue; detecting a first optical signal; extracting a first measurement of peripheral capillary oxygen saturation from the first optical signal; qualifying the first measurement of peripheral capillary oxygen saturation as a baseline; detecting a second optical signal with the optical sensor; extracting a second measurement of peripheral capillary oxygen saturation from the second optical signal; qualifying the second measurement of peripheral capillary oxygen saturation; storing the second measurement of peripheral capillary oxygen saturation as a tag feature set; storing a history; determining animal distress based on the difference between the second measurement of peripheral capillary oxygen saturation and the baseline; and sending an instruction to the tag.
