Ultrasound-guided injection of contrast medium into the crus penis for diagnosis of erection failure in bulls

The objectives of this study were to demonstrate the ability to cannulate the crurae of the bull’s penis under ultrasound guidance, to demonstrate contrast medium injected by this route in the distal penis, and to confirm the technique to be safe and repeatable. Five adult bulls with normal serving ability were used, one being subjected to the procedure twice. The procedure was performed with the bulls under general anesthesia and in lateral recumbency. A spinal needle was passed through the skin and into the crus penis under ultrasound guidance and two syringes containing an iodine-based contrast medium were connected to it. Stimulation using an electro-ejaculator with a rectal probe was initiated, and when the penis started developing an erection, 50–100 ml of contrast medium was injected. Lateral and ventro-dorsal radiographs were taken of the extended penis during, and at intervals after, injection. After a rest period of 5 min, clearance of the contrast medium was confirmed and the procedure was repeated on the other crus penis. Each case therefore, contained two attempts. Successful cannulation of the crus penis was confirmed by observing indentation of its fibrous wall by the needle, free flow of blood, lack of resistance to the injection of air, which could be seen in the crus, and fluctuation of resistance to injection in synchrony with the pulsation of the electro-ejaculator. Contrast medium was demonstrated in the mid or distal portion of the penis in all six cases, or on 9 of the 12 attempts. Attainment of penile erection, a larger volume of contrast medium, and the order of cannulation all enhanced flow of contrast medium to the distal portion of the penis, with the first crus giving better results. On one occasion the needle worked out of the crus penis during stimulation, resulting in injection of contrast medium into the corpus spongiosum penis. All bulls recovered uneventfully and returned to normal serving ability. It is concluded that ultrasound-guided cannulation of the crus penis is a safe and successful method for the injection of contrast medium for contrast studies of the penis, and is less invasive than the surgical method.