For optimal reliability, where should pulse oximetry probes be placed on unconscious, sedated, or anesthetized dogs?

Placing pulse oximetry probes on the tongue of unconscious, sedated, or anesthetized dogs is optimal for several reasons. The tongue is a highly vascularized area, which means that it has a rich blood supply. This facilitates accurate readings of oxygen saturation levels since there’s greater blood flow and a larger volume of blood present in the tongue compared to other areas. Moreover, the soft tissue of the tongue allows the probe to make good contact, reducing movement artifacts that can interfere with measurements.

Additionally, the tongue's location provides a central coupling for the measurement of arterial oxygen saturation, which is vital in assessing the overall oxygenation status of the patient in critical situations. This centralized position is generally less affected by peripheral factors which can skew readings from locations like the tail or toe, where circulation may be more variable or weaker, especially in sedated or unconscious animals.

Using the tongue is also practical in veterinary settings as it allows for quick and efficient checking of vital signs without the need to manipulate the animal excessively, which is crucial in maintaining the safety and comfort of the patient during monitoring procedures.