Atrial fibrillation associated with central nervous symptoms and colic in a horse: a case of equine cardiomyopathy.

This research article presents a case study of an 18-year-old horse suffering from atrial fibrillation symptoms, such as lethargy, blindness, and atypical movement, alongside colic. The study concludes that these were caused by congestive heart failure due to cardiomyopathy.

Clinical Presentation of the Horse

• The horse, a Dutch Warmblood mare of 18 years of age, was brought in primarily due to a colic condition. The horse was also demonstrating signficant central nervous symptoms, including lethargy, complete blindness, continuous pressings of her head, loss of muscle coordination (ataxia), and unusual circular movements.
• A rectal examination of the horse discovered a hard mass along with an excessive amount of fluid (oedema) around the cranial mesenteric artery.

Laboratory Findings and Clinical Observation

• The bloodwork showed increased level of liver enzymes and ammonia. Such abnormalities in liver function tests could be suggestive of liver disease or damage.
• Upon examination, the horse was found to have an erratic and irregular heart rhythm, a condition known as atrial fibrillation. This was noticed due to varied pulse frequency ranging from 36 to 52 beats per minute.
• Through a stethoscope, a repeating pattern of heart ‘murmurs’ was detected, with the maximum intensity on the right side of the chest.

Postmortem Findings and Final Diagnosis

• Postmortem examination revealed an enlargement of the right atrium, indicating a condition known as eccentric hypertrophy. In addition, the heart muscle exhibited pale and spotted discolorations, particularly on the right ventricle.
• There were secondary venous congestions observed in the azygos and mesenteric veins. Such a condition is generally associated with poor blood flow due to a weakened heart.
• The observable changes in the liver were indicative of a long-term (chronic) congestion situation.
• Despite the normal pulse rate, the observations and findings pointed toward congestive heart failure as a result of a particular type of heart disease known as cardiomyopathy. This was concluded to be the underlying cause of the central nervous symptoms and colic in the horse.