149 Preliminary Results of the Oxytocin Treatment on the Collection of Cat Semen by Urethral Catheterization After Pharmacological Induction

Abstract

Urethral catheterization after pharmacological induction (Ur.Ca.P.I.) has been developed as a method to collect semen from cats (Zambelli et al. 2008 Theriogenology 69, 485-490). This procedure is based on contraction of the vas deferens induced by the α-agonist medetomidine and the subsequent release of sperm into the urethra. To ensure adequate sedation, the medetomidine dosage is 130 µg kg⁻¹. Usually, a single collection of semen is done by catheterization immediately after medetomidine takes effect. A 3.5 French (Fr) gauge urinary tom cat catheter with the tip cut is inserted 90 mm deep into the urethra. Even in the absence of clinical signs, the cut catheter tip may cause minor trauma to the urethral mucosa. Aims of this study were to test a new catheter and evaluate effects of oxytocin administration on quality and quantity of semen collected. The study was performed on 8 client-owned, pubertal domestic cats, 10 to 18 months old. These cats were randomly allocated into 2 groups: control and treatment, with 3 and 5 cats, respectively. In each group, 2 semen collections were performed. The catheter had a diameter of 4 Fr and a rounded tip without mandrel and it was inserted 90 mm deep. In both groups, the first collection was performed as effects of medetomidine were apparent. In the control group, the second collection was done 10 min later. However, in the treated group, 5 IU of oxytocin was injected intramuscularly immediately after semen collection, with the second collection performed 10 min later. Semen was evaluated for volume, concentration, rate of progressive motility, curvilinear speed (VCL), morphology, and vitality. Comparisons between collections and between groups were done with a Student’s t-test. Comparing the second versus first collection in the control group, there was only an increase in volume (9.33 v. 2.67 µL; P < 0.05). In contrast, in the oxytocin group, all parameters evaluated were better (P < 0.05) for the second collection. As expected, the first collection was not different between the 2 groups for any parameter. However, for the second collection, there were differences (P < 0.05) between the oxytocin and the control group for volume (12.6 v. 3.7 µL), concentration (1252.6 v. 858 × 10⁶ sperm mL⁻¹), progressive motility (90.2 v. 77.8%), VCL (137.71 v. 117.94 µm s⁻¹), morphologically normal sperm (87.0 v. 81.4%), and vitality (86.4 v. 82.8%). Oxytocin may be involved in mobilization of sperm from the epididymis. We concluded that oxytocin improved recovery of sperm from epididymal reserves, resulting in sperm with better morphology and function than those present in the vas deferens.