You are working at a mixed animal practice in Missouri and y…

Yоu аre wоrking аt а mixed animal practice in Missоuri and you have a healthy canine patient under propofol anesthesia for a quick laceration cleaning and suturing. It is a hunting dog that cut herself on a fence while chasing a squirrel instead of looking for pheasants. The dog is breathing room air and has a respiratory rate of 6 breaths/minute. You notice the pulse oximetry value is decreasing to 85% (normal is 95-100%). What is the MOST LIKELY reason for the decrease in the pulse oximetry value? There’s no hidden clue in the picture.