Successful non-surgical treatment of priapism in a breeding stallion.

Abstract

Priapism is an abnormally prolonged erection of the penis normally not associated with sexual desire. It can occur in horses following phenothiazine tranquilizer administration. In general, priapism therapy consists of slings, massage, diuretics, cholinergic blockade and surgery. A 17-year-old, 538-kg KWPN breeding stallion was referred with priapism of > 4 days duration. Priapism occurred on the farm after a single IM injection of 15 ml imidocarb for treatment of suspected piroplasmosis (Babesia PCR positive). The horse was referred to a clinic where he was treated with 12ml flunixin meglumine IV, 30ml dexamethasone IV, 5ml furosemide IM and nadroparine calcique SC. Hematology and biochemistry were within normal limits except for a slight elevation of ASAT, LHD and total bilirubin. He was correctly vaccinated against influenza/tetanus/equine herpes virus and negative for all equine venereal diseases. On arrival the body score was 7/9 and a completely normal systemic and reproductive exam except for a non-painful erect penis, which he was unable to retract. Surgical creation of a vascular shunt between the corpus cavernosum penis (CCP) and the corpus spongiosum (CS) was proposed but rejected. After sedation with detomidine and butorphanol IV,10 mg phenylephrine diluted in 5ml NaCl 0.9% was injected twice in the CCP in 24 hours, at 1cm dorso-caudal to the corona glandis of the penis. After the second injection, permanent detumescence was achieved.Paralysis/paraphimosis necessitated 2 months of meloxicam treatment and use of a penile suspensory device to keep the penis in position. An initial 4-week intense acupuncture treatment did not resolve the paraphimosis. During a 2-month period, 3 cold showers of 30 minutes each were applied daily, each time resulting in partial retraction. He also received 60 ml Vitamin B per os daily for 3 months. Seven months post-injury, semen could only be collected via pharmacologically induced ejaculation (100%). Despite his excellent libido, regular trials to collect semen on the dummy, using three different AVs and with the aid of systemic gabapentin, clomipramine, oxytocin, phenylbutazone, xylazine, gonadotropin, topical testosterone gel and hot compresses at the root of the penis never resulted in effective ejaculation. Ultrasonographic examination revealed multiple distinct hyperechogenic areas in the CC. Twenty months post injury the stallion, ejaculated for the first time on the dummy in a hot and tight Colorado AV while under clomipramine, oxytocin, phenylbutazone and xylazine medication. All medication was gradually discontinued over the ensuing month. Until today he has remained active as a fertile breeding stallion without using any medication. This case shows that non-surgical treatment for priapism can be a valid alternative for the stallion to return to a normal full-time breeding activity on the dummy.