Dear Daisy Dog: AJ, my 10-year-old Chihuahua, takes enalapril for his chronic heart valve disease. The veterinarian recommended chest x-rays or an ultrasound with the cardiologist, but I can’t afford either. Without them, how will I know if AJ’s heart disease is getting worse?

Daisy Responds: Monitor his sleeping respiratory rate (SRR), the number of breaths he takes per minute while he’s sleeping quietly. Count how many times AJ’s chest expands (inhalation),  gets smaller (exhalation) and then pauses; each cycle is one breath.

Don’t count when he’s actively dreaming and his body is twitching, or when he’s especially warm after falling asleep in the sun.

Research shows that healthy dogs and those with stable heart conditions have an SRR of up to 25 breaths per minute. Studies indicate that an abnormally high SRR can predict the onset of congestive heart failure, the term used when the heart is so weak that fluid builds up in the lungs and breathing becomes difficult.

Check AJ’s SRR daily for a week to establish his baseline average. Then monitor and record his SRR every two or three days. If you see the number increasing, return to daily monitoring.

If his SRR climbs above 25 for two or three days, call the animal hospital to schedule an appointment. Your veterinarian may decide to transition AJ to a prescription heart diet, or add one or more heart medicines to improve his heart function.