Concentrations of carnitine in the seminal fluid of normospermic, vasectomized, and castrated dogs

Concentrations of total carnitine (free and esterified) were determined in seminal fluids from 12 normospermic dogs before treatment and from the same 12 dogs after assignment to control, vasectomized, or castrated treatment groups (4 dogs each). Before treatment, the mean concentration (+/- SD) of carnitine in seminal fluid was 946 +/- 345 nmol/ml and was not significantly different (P greater than 0.05) among groups on any seminal collection day. After surgery, mean concentrations of carnitine in seminal fluid from vasectomized and castrated dogs were 49 +/- 9 and 14 +/- 5 nmol/ml, respectively and were lower (P less than 0.001) than the mean concentration in control (sexually intact) dogs. Dogs with obstructive azoospermia may be distinguished from those with aspermatogenesis (secretory azoospermia) by measuring seminal carnitine concentration. Seemingly, the epididymis is the major source of carnitine in canine seminal fluid, because the concentration of carnitine in prostatic fluid was only 58 +/- 53 nmol/ml, whereas the concentration of carnitine in 6 pools of epididymal fluid was 18.8 +/- 3.9 mumol/ml.