Sleeping and resting respiratory rates in healthy adult cats and cats with subclinical heart disease

Sleeping and resting respiratory rates are commonly measured variables in patients with cardiac disease. However, little information is available on these variables in healthy client-owned cats or cats with subclinical heart disease (SHD). Therefore, we examined and characterized the sleeping respiratory rate (SRR) and resting respiratory rate (RRR) in 59 echocardiographically normal (EN) and 28 apparently healthy (AH) cats, and 54 SHD cats acquired by the cat owners in the home environment on eight to 10 separate occasions. The within-cat mean sleeping respiratory rate (SRRmean) in EN cats, AH cats and SHD cats with mild or moderate left atrial (LA) enlargement (as defined by quantiles of the ratio of the LA to the aorta [LA:AO]) was consistently <30 breaths/min; median SRRmean approximated 21 breaths/min. The SRRmean of SHD cats with severe LA enlargement sometimes exceeded 30 breaths/min, and was higher than SRRmean of other SHD cats ( P <0.05). The within-cat mean resting respiratory rate was consistently higher than SRRmean ( P <0.05). Age and geographic location, but not bodyweight, affected SRRmean in EN and AH cats. Within-cat SRR and within-cat RRR did not vary markedly from day-to-day, as evidenced by a low within-cat coefficient of variation. Data acquisition was considered easy or non-problematic by most participants. Our data provide useful guidelines for SRR and RRR, obtained in the home environment, in healthy cats and cats with SHD, and might prove useful in managing cats with clinical heart disease. Cats with SRRmean >30 breaths/min and cats with multiple SRR measurements >30 breaths/min likely warrant additional evaluation.