Retrograde ejaculation and hypothyroidism were diagnosed in a 19-mo-ol
d Labrador retriever: The retrograde ejaculation was reversed followin
g the administration of the sympathomimetic agent, pseudoephedrine hyd
rochloride, at a dose of 4 mg/kg per os given 1 and 3 h before semen c
ollection. Antegrade ejaculation failed to occur after normalization o
f serum thyroid hormone levels by thyroxine supplementation. The patho
physiology of retrograde ejaculation is reviewed.