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Rabbit Heart Disease - Two Case Studies

by Suzanne Smith

In the late nineties, I had misfortune of dealing with heart disease in two of my four rabbits. One had a heart arrhythmia while the other had a heart murmur. Since not much is known about rabbit heart disease, I thought I should tell their stories.

One summer, when we estimated Hazy was about 5 years old, I noticed that she was a little more reclusive, less active, sleeping in more protected places, and gaining weight. She also wasn't jumping onto the couch as often as she used to. When I took her in for a check-up, the veterinarian detected a heart murmur. An ultrasound revealed that she had two structural defects in her heart. The most severe was the pulmonic stenosis. The second was a small VSD, 3-4 mm. The first ultrasound
didn't show much damage to her heart. Over the next three years, her health steadily declined. She didn't require any medication and for the most part functioned normally. The changes were subtle ones in her behavior. Two years later she was responding poorly in the summer heat. While the other rabbits seemed fine, she would be laying in her cage panting, breathing hard. Another ultrasound showed that the defects were damaging her heart. The right ventricle wall was thickened. The aorta was enlarged, resulting in a large difference in pressure on each side of the valve. In Hazy, what I noticed was an intolerance to any form of heat and dizziness. When fall arrived, she seemed to be doing much better. The following summer was not a good one. In August Hazy suddenly refused food and appeared to be out of it. Respiratory rate appeared to be high. She was placed on Lasix and Enalipril. Hazy responded well to the medication and started reverting to her old self. A mere ten days later, she seemed overly stressed from receiving her medication, but settled down within 15 minutes. When I woke up the next morning, she had passed away.

We were very lucky in discovering Sasha's heart arrhythmia. She had been to the veterinarian for a problem with her paw. During a recheck a month later, my veterinarian detected an irregular heart beat. She was six years old and didn't display any symptoms at all. I may not have found it until it was too late, if it weren't for that appointment. We scheduled an ultrasound and echocardiogram which showed that the left atrium and ventricle were enlarged. Her heart rate was 360 beats per
minute and irregular. Systolic function was mildly decreased. The assessment was atrial fibrillation, volume overload and mildly decreased left ventricular systolic function. The cause of these changes was not evident. At that time we couldn't find any other cases of rabbits with this condition, so we tried enalipril and followed the dosage for cats. Her heart started beating normally again. For the next eighteen months she functioned as a normal rabbit who just needed medicine every day. In rabbits, the subtle changes can signal serious problems. In the course of a few days I noticed that she seemed slightly slower in her routine and that sometimes she stuck her nose up in the air. Weird- so I took her in. An x-ray revealed that she had a significant amount of fluid around her heart and it was compressing her trachea, hence her need to raise her nose to breathe. She was placed on Lasix and appeared to return to her normal self. Two weeks later she again was sluggish. A trip to the vet didn't show any problems. The next morning she couldn't stand. Her heart was in atrial fibrillation and sadly, terminal. Within a day she was humanely euthanized.

Copyright 2001- Suzanne Smith