Sperm Tail Defects and Abnormal Testicular Blood Flow in a Beagle Dog: A Case Report.

A 5-year-old male Beagle dog produced ejaculates with a high percentage of spermatozoa with abnormal morphology, especially sperm tail defects. Although libido and semen volume were normal, ejaculates showed asthenospermia, oligozoospermia, and teratozoospermia. The spermatozoa exhibited morphologic defects affecting the flagellum, mainly coiled tails with or without macrocephalia (33.5 ± 2.1%), bent tails (18.3 ± 3.4%), and proximal cytoplasmic droplets (6.7 ± 2.8%). The peripheral plasma testosterone level was 2.76 ± 0.21 ng/mL. The resistive index and the pulsatility index from marginal and intratesticular vessels measured by Doppler ultrasound showed higher values in the right testicle than in the left testicle. Histologic evaluation revealed focal reduction in the number of germ cells and sperm in the seminiferous tubules in the right testicle. This is the first report that describes simultaneously the presence of sperm tail defects in the ejaculate and changes in the blood flow of testicular vessels in the dog.