Arrhythmogenic Right Ventricular Cardiomyopathy and the Shetland Sheepdog

This distinction decides which specialist your dog needs, and owners are the only witnesses. What you notice in the first ten seconds matters more than anything measured later.

When a Shetland Sheepdog does turn out to have an arrhythmia, the underlying cause is generally something other than ARVC. Rhythm disturbances arise from valve disease, from congenital defects present since birth, from systemic illness affecting electrolytes, from pain and from thyroid disease. Hypothyroidism is one of the five conditions documented in this breed, and low thyroid hormone can slow the heart and alter its behaviour, which is one concrete reason a cardiac workup in a Sheltie usually includes bloodwork.

The diagnostic path is fairly standard whatever the suspicion. A stethoscope catches a murmur or an irregular beat. An electrocardiogram records the rhythm at that moment. Because arrhythmias are intermittent by nature, a normal in-clinic trace proves very little, so a Holter monitor worn at home for twenty four hours is often the tool that actually finds the problem. An ultrasound scan then shows whether the muscle and valves are structurally abnormal.

There is a breed detail worth flagging before any of this happens. Some cardiac procedures and the sedation used for imaging bring the Sheltie's documented MDR1 drug sensitivity into play. If your dog is heading for a cardiology referral, get the genotype tested first so the specialist is not making drug choices around an unknown.