If your horse is exhibiting signs of colic, weight loss, or diarrhea, your veterinarian might reach for an ultrasound probe to get a glimpse of what is going on inside the animal’s abdomen. Some serious conditions, however, aren’t easily visible on ultrasound.

Because lymphadenopathy (enlarged lymph nodes) is a common finding upon post-mortem examination of horses with infectious, inflammatory, or cancerous disease, Betsy Vaughan, DVM, assistant clinical professor of Large Animal Ultrasound at the University of California (UC), Davis, School of Veterinary Medicine, set out to determine if this condition could be identified on ultrasound, which might help veterinarians reach a conclusive diagnosis and implement treatment before horses are euthanized. She presented the results of her study at the 2013 American Association of Equine Practitioners convention, held Dec. 7-11 in Nashville, Tenn.

"Mesenteric lymph nodes are not often visualized by ultrasound because of their location deep within the horse’s abdomen," Vaughan said. "The cecal mesentery (connective tissue attached to the cecum, part of the large intestine), however, is located adjacent to the body wall in the right flank region and can be readily visualized with ultrasound in most horses."

Therefore, she proposed that using ultrasound to evaluate this structure might reveal signs of lymphadenopathy and direct further diagnostic testing