Why monitor sleeping respiratory rate?

Sleeping respiratory rate (SRR) monitoring is very useful in assessing for the onset or reoccurrence of left sided congestive heart failure (CHF) in both dogs and cats.

Left sided congestive heart failure occurs when pressure in the top left heart chamber (left atrium) increases and blood back up into vessels within the lungs (pulmonary vasculature). The high pressure in the pulmonary vasculature results in fluid entering the airspaces in the lungs (pulmonary oedema).

The early identification of CHF is very important as this is often when medications are first recommended for animals with common cardiac diseases such as degenerative valve disease, dilated cardiomyopathy and hypertrophic cardiomyopathy.

How to monitor sleeping respiratory rate?

The recording should be done when the animal is asleep in a thermo-neutral environment (ie, not too cold, not too hot). This should be repeated daily for 2-3 days (to get a baseline variation), and then a few times a week up to daily depending on the stage of the disease.

We have created a SRR form that you can download and use.

Normal SRR

Normal SRR in dogs and cats is <30 breaths/min, often in the high-teens or low 20s. A SRR that does not decrease to <30 breaths/min in patients with underlying heart disease is strongly suggestive of the development of CHF. However, primary respiratory disease with concurrent subclinical heart disease needs to be ruled out.

What to do if the SRR is high?

Please contact your vet if your pets SRR does not decrease to <30 breaths/min.

If the SRR is elevated, several options exist. If everything else suggests CHF as the cause, then thoracic radiographs should be obtained. If there are no contraindications, a short diuretic trial can be employed.

Other causes of elevated SRR include (but are not limited to) morbid obesity, pulmonary thromboembolic disease, pulmonary hypertension, severe hypoxemia of any cause (e.g. severe anemia), acute pneumonia, severe heat, pyrexia of any cause.

What do I do if the patient is already receiving diuretics or other drugs for CHF?

If the patient is already on medications for CHF, then SRR can be used to monitor for relapsing CHF. A patient with well controlled CHF will have a normal SRR (<30 breaths/min). If CHF starts to recur, the SRR will start to creep up over time, allowing intervention earlier in the disease process, before the situation becomes critical.

Assessing and recording of Sleeping Respiratory Rate is:

Probably the most sensitive indicator of developing pulmonary edema or pleural effusion in dogs and cats.

A very useful home-monitoring technique for owners to perform.

Used once a diagnosis of CHF has been made (and is now controlled), or where substantial heart disease exists and is likely to result in CHF at some future stage.

In addition to being a great home monitoring aid, involving the owner in this process helps overcome the "need to do something" that many owners and veterinarians exhibit when dealing with heart disease.