Nottrott said the new technique requires less needle repositioning and would theoretically take less time than an X ray-guided technique, meaning reduced risk of infection and probably lower levels of stress for the horse. | Photo: Courtesy K. Nottrott

A new ultrasound-guided technique, however, is showing promise, said Knut Nottrott, DVM, of the Pole Equin at VetAgro Sup in Marcy L’Étoile (Equine Teaching Hospital of Lyon), in France.

Currently, practitioners take one or more X rays during needle positioning to check needle placement before injecting. Despite the common use of ultrasound guidance in other needle placement techniques, traditionally this modality hasn’t been useful for visualizing within the hoof because the wall blocks the ultrasound waves, Nottrott said. So radiography has been the imaging technique of choice.

Scientists recently tried a new technique, however, by first placing the hoof in a 60° flexed position—a navicular or Hickman block position (a special block in which the horse rests a hoof while the veterinarian takes a navicular bone X ray). Then by accessing the foot laterally through the tissue above the hoof on the side, the scientists were able to “see” the needle via ultrasound entering the navicular bursa without interference from the hoof wall. This led not only to successful injection but also to reduced risks for both horse and veterinarian