Efficient Association between PGF2α and Methyl 4‐hydroxybenzoate Sex Pheromone Prior to Electroejaculation in Dogs

Abstract

Electroejaculation is a technique that can be used to collect semen from canines, but its use with this group of animals is restricted by low success rate and low semen quality. Here, we evaluated whether pharmacological and sexual sensory stimuli, which may affect ejaculation, can increase electroejaculation efficiency and improve ejaculate quality. We worked with 20 dogs of mixed breed weighing between 5.3 and 22.2 kg, divided into two groups. Both groups were exposed to a spayed female for 10 min, but in the second group, the same spayed female had her vagina impregnated with methyl 4-hydroxybenzoate synthetic pheromone for 10 min and after receiving dinoprost tromethamine IM, 0.1 mg/kg. After stimulation, all dogs were chemically restrained with ketamine, 8 mg/kg, IM; and xylazine, 1 mg/kg, IM, and subjected to electroejaculation protocol. We obtained 100% of antegrade ejaculate in treatments when the spayed female had her vagina impregnated with pheromone and 80% when she did not. Sperm motility was significantly different (p < 0.05) between controls and the test group (10.1 ± 4.5 and 43.0 ± 8.3, respectively). We concluded that the adopted electroejaculation protocol was efficient and that the PGF2α associated with sexual sensory stimulation can improve semen quality in dogs undergoing the procedure.

The Efficiency of Synthetic Sex Pheromones in Sexual Arousal Stimulation in Domestic Dogs

“…However, Kruse and Howard (1983) in their study concluded that methyl p-hydroxybenzoate cannot be considered as a key sexual attractant for male dogs. Santos et al (2013), using methyl 4-hydroxybenzoate (cat. H5501; Sigma-Aldrich ® , Saint Louis, MO, USA) in their study also stated that "there was no sexual behavior observed between the dogs and the bitch (....), even though she was impregnated with artificial pheromone".…”

Methyl paraben as a sex pheromone in canine urine – is the question still open?

“…However, analysis of the literature on the activity of methyl paraben in the context of sexual arousal shows a lack of efficiency of this substance (Kruse and Howard 1983, Tonosaki and Tucker 1985, Dzięcioł et al 2011. In the original article reporting an effective association between PGF2h and methyl 4-hydroxybenzoate prior to electroejaculation in dogs, while the authors obtained better results in a group of males exposed to methyl paraben, they also confirmed that there were no signs of sexual arousal observed in these males (Santos et al 2013). Also, while the influence of natural pheromones on physiological parameters (e.g., heart rate) in dogs was previously described by Dzięcioł et al (2012b), Santos et al (2013) did not find any differences between groups in heart and respiratory rate or rectal temperature.…”

“…In the original article reporting an effective association between PGF2h and methyl 4-hydroxybenzoate prior to electroejaculation in dogs, while the authors obtained better results in a group of males exposed to methyl paraben, they also confirmed that there were no signs of sexual arousal observed in these males (Santos et al 2013). Also, while the influence of natural pheromones on physiological parameters (e.g., heart rate) in dogs was previously described by Dzięcioł et al (2012b), Santos et al (2013) did not find any differences between groups in heart and respiratory rate or rectal temperature. In this case, a probable explanation for the better results obtained in males injected with PGF2α and stimulated by MP is the stimulating influence of PGF2α (Estienne and Harper 2000, Kozink et al 2002).…”

“…(1979) is still the most often cited study (Person 1985, Pageat and Gaulnier 2003, Kustritz 2005, Santos et al 2013, Wani et al 2013. Described as a primary dog sex pheromone, methyl paraben has become a component of commercially available products (Eau D'Estrus, Synbiotics, USA) recommended to both veterinarians and breeders as a useful tool for male canine sexual stimulation (Kustritz 2005, Kutzler 2005).…”