Retrograde Ejaculation in Dogs
What is Retrograde Ejaculation?
A retrograde (or backward) flow of a small quantity of spermatozoa into the bladder is a normal event. However, a retrograde flow of large quantities of spermatozoa back into the bladder is abnormal. Such abnormality may occur during ejaculation as a result of a partial or complete absence of contractions of the bladder neck during semen expulsion. The bladder becomes the least resistant pathway for seminal fluids coming from the urethra when it occurs, and the ejaculate produced from the penis is either scant or absent, and spermatozoa can be retrieved in large quantities from the bladder.
Generally following erection and normal pelvic thrusting a normal dog produces an ejaculate composed of 0.5 to 2.5 ml of presperm (clear fluid) and a sperm rich fraction (milky substance), and 4 to 45 ml of clear fluid fraction. It usually leads to the suspicion that retrograde ejaculation has occurred when there is a complete lack of ejaculate or production of minimal amount of ejaculate (i.e. 0.1 to 0.3 ml).
How Can it be Treated?
Success of treatment depends on the cause of the failure for the bladder neck to contract. Treatment is generally unsuccessful if there is a structural defect to the bladder wall. However, if the defect is neuropathic (diabetes, or prolonged treatment with drugs interfering with contraction of bladder neck), successful treatment of diabetes, or ceastion of the medication concerned normally rectifies the situation.
In normal dogs the vas deferens, epididymis, and prostate and bladder neck (all structures involved in production and passage of spermatozoa) are mainly under the control of sympathetic nervous system which causes contraction of all these structures to occur during times of ejaculation. Hence if the bladder structure appears normal and the above neuropathic causes have been ruled out affected dogs are often placed on appropriate medication before breeding or semen collection in an attempt to cause closure of the bladder neck during the ejaculation process.
Is Retrograde Ejaculation a Common Problem?
It is considered as a rare event but may occur more frequently than expected. Inadequate manipulation of the dog penis during semen collection can increase the chance of retrograde ejaculation by 60%. A lack of interest in the bitch to be mated or fear of a new environment can lead to insufficient activation of the sympathetic nervous system and hence retrograde ejaculation.
Retrograde ejaculation should be ruled out when low sperm numbers with minimal quantities of fluid or absence of semen or fluid occurs. This is commonly done by collecting urine samples from the dog and looking for large numbers of spermatozoa in the sample.