Effect of post-thaw dilution with caffeine, pentoxifylline, 2’-deoxyadenosine and prostatic fluid on motility of frozen-thawed dog semen

The aim of the experiment was to evaluate the motility pattern of frozen-thawed canine semen to which pentoxifyilline (PTX), caffeine (CAF), 2’-deoxyadenosine (DX), and prostatic fluid (PROST) were added after thawing. Semen evaluations were performed using computer-assisted sperm analysis (CASA) at thawing and during 120 min of incubation at 37 °C. Three experiments were conducted: 1) to establish which concentrations of stimulants work best; 2) to investigate the interaction between thawing rate and addition of CAF 5 mM, PTX 2.5 mM and PROST; 3) to evaluate the effect of PTX 7.5 mM and DX 5 mM on semen motility after thawing. In experiment 1, ALH and VCL were enhanced at thawing by CAF 7.5 mM (CAF 7.5: 9.1 ± 0.5 μm; control: 6.7 ± 0.4 μm) and DX 5 and 7.5 mM (DX 5: 199.1 ± 12.8 μm/s; DX 7.5: 197.3 ± 13.9 μm/s; control: 162.5 ± 8.4 μm/s), while PTX 2.5-5-7.5 mM improved TOT after 120 min of incubation. In experiment 2, PROST lowered ALH values throughout incubation (P < 0.05) with respect to the other treatments, in particular when compared to CAF at Time = 30 and at Time = 60. In experiment 3, PTX 7.5 mM improved VAP (PTX: 101.6 ± 6.8 μm/s; control: 81.9 ± 10.5 μm/s), VSL (PTX: 82.9 ± 6.4 μm/s; control: 65.9 ± 9.8 μm/s), VCL (PTX: 214.3 ± 13.3 μm/s; control:167 ± 15.7 μm/s), ALH (PTX: 10.5 ± 0.3; control: 7.3 ± 1.4 μm), PM (PTX: 11.3 ± 4.2%; control: 7.7 ± 3.9%) and TOT (PTX: 20.1 ± 5.3%; control:15.6 ± 5.6%) at Time = 120, while DX 5 mM influenced VCL at Time = 60 (DX: 218.3 ± 14.3 μm/s; control: 188.5 ± 7.5 μm/s, P < 0.05). Motility stimulants may be useful for enhancing motility of canine frozen-thawed spermatozoa without affecting sperm longevity.