Sperm collection in the domestic cat: A comparison of two techniques

Semen collection in cats in the clinic setting can be difficult. However, semen analysis is vital when evaluating breeding soundness of a male. Electroejaculation (EEJ) is currently the most reliable semen collection method but requires specialized equipment and training of the operator. Chemical ejaculation followed by urethral catheterization (UC) is a technique that allows semen collection without special equipment: a catheter is placed into the urethra of a sedated tom and semen is collected passively into the catheter. Earlier studies used the sedative medetomidine at high doses for this procedure. However, medetomidine has been replaced with dexmedetomidine in some countries. This study sought to compare the results of EEJ and UC for semen collection in the domestic cat using dexmedetomidine, a potent α2-adrenoceptor agonist (α2A), as a substitute for medetomidine at the equivalent dose to that used in earlier studies. Twelve domestic cats were collected thrice at weekly intervals. All cats received intramuscular ketamine (5 mg/kg) and intramuscular dexmedetomidine (30 μg/kg) for initial cleanout via EEJ, then randomly underwent either EEJ or UC one week apart. The EEJ was performed under the same anesthetic protocol as the initial cleanout. The UC was performed using intramuscular dexmedetomidine at a dose of 60 μg/kg. Success of collection, total sperm number, sperm morphology, and motility characteristics were analyzed. Sperm was collected successfully from all 12 cats via EEJ and from 11/12 via UC. There were no significant differences in the percentage of total motile, progressively motile, or morphologically normal sperm between ejaculate types when averaged across all cats or individual cats. Although UC yielded a lower volume and higher concentration ejaculate, it consistently produced a lower total sperm number than ejaculates retrieved via EEJ (17.91 x 10⁶ total sperm for UC versus 46.51 x 10⁶ total sperm for EEJ). These results indicated that dexmedetomidine is a very effective sedative and performed satisfactorily in both procedures at the doses used in this study. It was also safe with no adverse effects on healthy toms. EEJ remained the most reliable in terms of assessing semen quality and retrieving semen with adequate number of sperm for breeding purposes. However, UC with dexmedetomidine at this dose demonstrated a 92 % success rate, presenting itself as a remarkably consistent alternative.