Penile erection and contraction of penile muscles the spinal and intact dog

Abstract

Electromyographic recordings from penile muscles and observations of erection were made while stimulating various areas of the penis of dogs. Three distinct patterns of responses were observed in both the chronic spinal and intact dogs depending on the area of penis stimulated. Rubbing behind the bulbus glandis elicited tonic contraction of the ischiourethral muscle, rhythmic contraction of the bulbocavernosus and ischiocavernosus muscles, and rapid penile tumescence. During a refractory period which followed this reaction, a 2nd similar reflex was elicited by applying pressure behind the bulbus glandis and rubbing the urethral process. The responses to this stimulus were tonic contraction of the ischiourethral muscle, rhythmic contraction of the bulbocavernosus and ischiocavernosus muscles, and slow penile tumescence. A 3rd reflex, elicited by stimulating the corona glandis, resulted in tonic contraction of the bulbocavernosus and ischiocavernosus muscles and rapid detumescence. The possible role of these reflexes in penile erection and copulation in the dog are discussed.