Objectives: We compared the effects of two alpha (α)₂-adrenergic agonists on semen traits. Methods: In this study, 13 adult domestic cats were divided into two experimental groups, according to the chemical ejaculation protocol used: the first group received medetomidine hydrochloride (100 µg/kg) and ketamine (5000 µg/kg); the second group received dexmedetomidine hydrochloride (25 µg/kg) and ketamine (5000 µg/kg), both by the intramuscular route. Results: The animals responded positively ( P >0.05) to chemical collection. Seminal parameters evaluated included volume, sperm vigor, total motility, progressive motility, sperm concentration, and the structural and functional integrity of the plasma membrane; sperm morphology values did not differ between groups ( P >0.05). Conclusions and relevance: The results indicated that dexmedetomidine is a more viable and economical alternative to medetomidine in domestic cats submitted to semen collection by urethral catheterization. Semen collection by urethral catheterization after using α₂-adrenergic agonists is a recently developed technique in feline species that is considered to be quick and highly applicable to assisted reproduction programs in felids.

This study aimed to evaluate the effect of treatment with equine chorionic gonadotrophin (eCG) on the follicular dynamics and function of crossbred cows with different circulating progesterone (P4) concentrations during synchronization of ovulation in a fixed-time artificial insemination (FTAI) protocol. To this end, 30 crossbred cows were submitted to a pre-synchronization protocol to ensure that all of them presented corpus luteum (CL) at the beginning of the protocol, and were evaluated by transrectal ultrasonography (TRUS) to verify the presence of CL. After that, the animals underwent an ovulation synchronization protocol and evaluation of follicular dynamics and vascularization by B-mode and power-Doppler ultrasound (US). High plasma P4 concentrations at the time of ovulation synchronization negatively influenced follicle diameter on day 10 (D10), preovulatory follicle diameter, and preovulatory follicle wall vascularization area (p0.05) similar to those of animals with low P4 concentration at the time of ovulation synchronization. Therefore, high P4 concentrations at the time of ovulation synchronization negatively influence follicular diameter and vascularization, and eCG can be used as a strategy to favor better follicular and luteal response in crossbred cows with high P4 concentrations submitted to an FTAI protocol.

Due to the peculiarities of the reproductive cycle of the female dog, which makes it difficult to accurately ascertain the date of conception, it may be challenging to precisely estimate the gestational age in bitches. Using fetal measurements obtained by ultrasound, it is possible to estimate the gestational age in dogs; however, due to the differences in size of the various breeds, such estimates may have a significant standard deviation, which represents less accuracy when specifying the date of birth. The purpose of this study was to evaluate pregnant female Chihuahuas, establishing relations between the fetal dimensions measured by ultrasound and the remaining time until delivery. Using 13 pregnant female Chihuahuas, weekly ultrasound assessments and measurements were performed, of the inner chorionic cavity, cranial-caudal length, biparietal diameter, abdominal diameter and thoracic diameter. Such parameters were retroactively correlated to the date of delivery, and linear regressions were established between the gestational measurements and remaining days until delivery. The fetal measurement presenting the highest correlation (r = 0.99; P<0.0001) and reliability (R2 = 0.98, P<0.0001) with the probable date of delivery was the biparietal diameter, a measurement that can be easily and safely obtained and, when applying a specific formula (Y = -15.46X1 + 38.72), can accurately predict the date of delivery in Chihuahua female dogs.

The objective of this study was to evaluate the effects of an hCG subdose applied at the Hou Hai acupoint as an ovulation inducer in donkeys. Eleven donkeys were distributed in randomized blocks in T1 = application of 1,500 IU of hCG intravenous (IV); T2 = 450 IU of hCG applied at the false acupoint (IV), and T3 = 450 IU of hCG applied at the Hou Hai acupoint. There was no difference (P > 0.05) between the treatments regarding the mean diameter of the pre-ovulatory follicle (34.5 ± 1.3 mm), the ovulation rate (96.97%), the interval between induction and ovulation (58.07 ± 16.82 h), the mean diameter of the CL (D0 = 23.0 ± 0.6; D2 = 27.7 ± 1.9 and D8 = 28.2 ± 0.8mm), and serum P4 concentrations (10.50 ± 2.99 ng.mL-1). The application of 450 IU of hCG at the Hou Hai acupoint increased ovulation rate (72.73%) more than 48 h after induction (P = 0.03) and a larger diameter of the CL on D4 (30.7 ± 5.1 mm) (P = 0.04). The vascularization area of the CL on D8, obtained by minimum number of colored pixel (NCP), was greater (P < 0.05) in the donkeys that received 1,500 IU of IV hCG (T1, 41.91 ± 1.17), and we found a positive correlation (P < 0.05) between mean NCP and P4 concentration in the donkeys that received 450 IU of hCG IV at the false acupoint (T2) or at the Hou Hai acupoint (T3). The application of 450 IU of hCG by IV route at the false acupoint or the Hou Hai acupoint was sufficient to induce ovulation in donkeys, demonstrating that the average dosage commonly used for this species is too high.