In a cat suspected of urethral obstruction, which vital sign should be checked first?

In a cat suspected of urethral obstruction, checking the heart rate first is crucial because alterations in heart rate can be indicative of the animal's physiological status and response to stress or pain. Urethral obstruction can lead to severe complications, including electrolyte imbalances and potential cardiac effects due to changes in fluid status.

An elevated heart rate may indicate pain, anxiety, or shock, while a bradycardic response might suggest a dire situation such as hyperkalemia (high potassium levels), which can occur due to obstruction. Monitoring the heart rate initially allows for quick assessment and immediate intervention if needed, guiding further evaluation and treatment.

While blood pressure, temperature, and pupillary light response are also important vital signs, they may not provide as immediate or direct information regarding the urgent state of circulation and perfusion in this specific context. Evaluating heart rate first prioritizes the assessment of any potential immediate cardiovascular compromise.