It could be that your pet just drank it's water a bit too fast - or it could be the first sign of a serious problem involving its heart or lungs. (2ndchance.info)
Again, I'm not sure if this is «a little higher than normal but within the tolerable range» or «a seriously abnormal sign of a serious problem», different sources seem to contradict each other on this (mechanics.stackexchange.com)
Other signs of a serious problem include severe headache, swelling in the arms or legs, fever, chills, dizziness, nauseua or vomiting, change in vaginal discharge, problems walking and problems urinating. (howtoadult.com)