Expression of GnRH receptor in the canine corpus luteum, and luteal function following deslorelin acetate-induced puberty delay

The goals of this study were as follows: (Experiment 1) to examine the basic capability of canine corpora lutea (CL) to respond to GnRH by assessing expression of gonadotropin-releasing hormone receptor (GnRH-R) in luteal samples collected throughout the luteal lifespan from non-pregnant dogs, and (Experiment 2) to investigate the effects of pre-pubertal application of the GnRH agonist deslorelin acetate on luteal function following the first oestrus. Mature CL were collected during the mid-luteal phase (days 30–45) from treated and control bitches. Transcript levels of several factors were determined: estrogen receptors (ESR1/ERα, ESR2/ERβ), progesterone (P4)-receptor (PGR), prolactin receptor (PRLR), PGE2-synthase (PTGES) and PGE2 receptors (PTGER2/EP2, PTGER4/EP4), vascular endothelial growth factor (VEGFA) and VEGF receptors (VEGFR1 and VEGFR2), cyclooxygenase 2 (COX2/PTGS2), steroidogenic acute regulatory protein (STAR) and 3β-hydroxysteroid dehydrogenase (3βHSD). Additionally, levels of Kisspeptin 1 (Kiss1) and its receptor (KISS1-R) were evaluated. Although generally low, GnRH-R expression was time dependent and was elevated during early dioestrus, with a significant decrease towards luteal regression. In deslorelin-treated and control dogs, its expression was either low or frequently below the detection limit. EP2 and VEGFR1 were higher in the treated group, which could be caused by a feedback mechanism after long-term suppression of reproductive activity. Despite large individual variations, 3βHSD was higher in the deslorelin-treated group. This, along with unchanged STAR expression, was apparently not mirrored in increased luteal functionality, because similar P4 levels were detected in both groups. Finally, the deslorelin-mediated long-term delay of puberty does not have negative carry-over effects on subsequent ovarian functionality in bitches

The first case of Brucella canis in Sweden: background, case report and recommendations from a northern European perspective

Infection with Brucella canis has been diagnosed in Sweden for the first time. It was diagnosed in a three-year-old breeding bitch with reproductive disturbances. Fifteen in-contact dogs were tested repeatedly and all of them were negative for B. canis. The source of infection could not be defined. The present article describes the case and the measures undertaken and gives a short review over B. canis. Recommendations on how to avoid the infection in non-endemic countries are given

Short-term clinical and hormonal effects of a deslorelin implant on late-prepubertal bitches – Based on flare-up signs

Gonadotropin-releasing hormone (GnRH) agonists offer an alternative to surgical sterilization in pre-pubertal dogs, preserving ovarian and uterine functions. However, the clinical and hormonal effects of GnRH agonist application during the late-prepubertal stage remain insufficiently understood. This study aimed to investigate the clinical effect (flare-up) and hormonal changes, specifically serum progesterone (P4) and estradiol (E2) levels, in bitches treated with 4.7 mg deslorelin acetate (DA) implants (Supre-lorin & REG;, Virbac, F) during the late prepubertal period. Sixteen clinically healthy kangal cross-breed bitches, aged 7-8 months, with a mean body weight of 20.5 & PLUSMN; 0.8 kg, were implanted with DA. Estrus signs were monitored daily, and blood and vaginal cytological samples were collected every other day for four weeks. Cytological changes were analyzed for overall and superficial cell index. Six out of sixteen DA-treated bitches (EST group; n = 6) exhibited clinical proestrus 8.6 & PLUSMN; 0.6 days after implant insertion. The mean serum concentrations of P4 and E2 at the onset of estrus were 1.38 & PLUSMN; 0.32 ng/ml and 37.38 & PLUSMN; 10.07 pg/ml, respectively. Notably, all non-estrus (N-EST group; n = 10) bitches demonstrated an increase in superficial cell index, in addition to expected cytological changes observed in the EST group. On the 18th day post-implantation, the EST group exhibited a significantly higher number of superficial cells compared to the N-EST group (p < 0.001). DA implantation resulted in cytological profile alterations accompanied by a slight increase in estrogen concentrations in all dogs. However, the flare-up response exhibited significant variability, differing from that observed in adult dogs. This study highlights the importance of meticulous timing and breed-specific considerations when utilizing DA for puberty manipulation in late-prepubertal bitches. The observed cytological and hormonal changes in response to DA implants provide valuable insights, but the variability in flare-up responses warrants further investigation. & COPY; 2023 Elsevier Inc. All rights reserved