Anoestrus in the Dog: a Fascinating Story

In the bitch, progression from early to late anoestrus is characterized by a higher amplitude and a larger number of gonadotrophin-releasing hormone (GnRH) pulses generated by the hypothalamus, an increase in the sensitivity of the pituitary to GnRH, and an increase in ovarian responsiveness to gonadotrophins. An increase in basal plasma follicle-stimulating hormone (FSH) concentration is a critical event required for initiation of folliculogenesis. A period of increased luteinizing hormone pulsatility has been reported shortly before the onset of pro-oestrus. Apart from these changes in the hypothalamic-pituitary-ovarian axis, there is also involvement of dopaminergic influences in the initiation of a new follicular phase in the bitch. Administration of the dopamine-agonists bromocriptine and cabergoline shortens the anoestrus and is associated with a decrease in the plasma prolactin concentration, suggesting that the shortened anoestrus is the result of suppression of prolactin secretion. Yet, the anoestrus is not shortened in bitches treated with metergoline, a drug, which in a low dosage lowers the plasma prolactin concentration via a serotonin-antagonistic pathway. In addition, under physiological conditions low plasma prolactin concentrations are found during the entire anoestrus. Furthermore, a low dosage of bromocriptine, insufficient to cause a decrease in the plasma prolactin concentration, prematurely induces folliculogenesis. These observations indicate that not the decrease in the plasma prolactin concentration, but another dopamine-agonistic influence plays a critical role in the transition to a new follicular phase. The dopamine-agonist induced shortening of the anoestrus is associated with a rapid rise in the basal plasma FSH concentration, similar to what is observed during the physiological late anoestrus. This observation underlines the importance of an increase in the circulating plasma FSH concentration in the initiation of folliculogenesis in the bitch.     

Detection and localization of regucalcin in spermatozoa of water buffalo (Bubalus bubalis): A calcium‐regulating multifunctional protein

Regucalcin (RGN) is a calcium‐regulating, anti‐apoptotic, antioxidative and antiproliferative multifunctional protein predominantly seen in liver and kidney. All these functions are very crucial during spermatogenesis and sperm maturation process until fertilization of the ovum. Although many studies have reported the wide distribution of regucalcin in the male reproductive tract of the rat, human and bovine, its presence in spermatozoa is yet to be demonstrated wherein calcium has a pivotal role in the transport, capacitation, acrosomal reaction and further fusion with ova. Here, we detected the expression of regucalcin mRNA and protein in buffalo spermatozoa using real‐time PCR and Western blot, respectively. The study detected two new regucalcin isoforms of 44 kDa and 48 kDa size along with the reported 34‐kDa, 28‐kDa and 24‐kDa isoforms, wherein the 34‐kDa isoform was found to be membrane associated in spermatozoa. Further, immunocytochemistry study localized the regucalcin protein in the acrosomal region of the caudal and ejaculated buffalo spermatozoa while it was detected in both cytoplasm and acrosomal region of testicular spermatozoa. This discovery of RGN in spermatozoa and localization in the acrosomal region will help to focus researchers to see its role in calcium‐related functions like capacitation, acrosomal reaction and membrane fusion. Overall, regucalcin may be a new fertility marker in buffalo and can be utilized for infertility treatments.     

Antinociceptive effect of buprenorphine and evaluation of the nociceptive withdrawal reflex in foals

ObjectiveTo elicit and evaluate the NWR (nociceptive withdrawal reflex) in 2 and 11 day old foals, to investigate if buprenorphine causes antinociception and determine if the NWR response changes with increasing age. The effect of buprenorphine on behaviour was also evaluated.Study designProspective, experimental cross-over trial.AnimalsNine Norwegian Fjord research foals.MethodsBuprenorphine, 10 μg kg⁻¹ was administered intramuscularly (IM) to the same foal at 2 days and at 11 days of age. The NWR and the effect of buprenorphine were evaluated by electromyograms recorded from the left deltoid muscle following electrical stimulation of the left lateral palmar nerve at the level of the pastern. Mentation, locomotor activity and respiratory rate were recorded before and after buprenorphine administration.ResultsWe were able to evoke the NWR and temporal summation in foals using this model. Buprenorphine decreased the root mean square amplitude following single electrical stimulation (p < 0.001) in both age groups, and increased the NWR threshold following single electrical stimulation in 2 day old foals (p = 0.0012). Repeated electrical stimulation at 2 Hz was more effective to elicit temporal summation compared to 5 Hz (p < 0.001). No effect of age upon the NWR threshold was found (p = 0.34). Sedation when left undisturbed (11 occasions), increased locomotor activity when handled (9 occasions) and tachypnea (13 occasions) were common side-effects of buprenorphine.Conclusion and clinical relevanceThese findings indicate that buprenorphine has antinociceptive effect in foals. Opioid side effects often recognized in adult horses also occur in foals.     

Minimal External Masculinization in a SRY-negative XX Male Podenco Dog

Normal mammalian sex differentiation takes place in three genetically controlled steps: chromosomal sex determination (XX or XY), gonadal differentiation and development of the phenotypic sex. Animals are considered to be sex reversed if chromosomal sex determination and gonadal development are not in agreement. In this report, sex reversal is described in a 1.5-year-old Podenco dog that was referred because of suspected recurrent growth of a previously removed os clitoridis in the vulva. With that exception the dog was phenotypically female, but had never been in oestrus and exhibited male behaviour. Abdominal ultrasonography showed a small tubular structure dorsal to the bladder, consistent with a uterus. An ovoid structure resembling a gonad was visible between the right kidney and inguinal canal. Plasma testosterone concentrations before and after GnRH administration indicated the presence of functional testicular tissue. Two testes, each with its epididymis and ductus deferens, and a complete bicornuate uterus were removed surgically. Cytogenetic analysis of peripheral blood lymphocytes showed a normal female karyotype (78, XX). These findings are consistent with the diagnosis of an XX male. PCR analysis of genomic DNA revealed that the SRY gene was absent. In summary, this report describes the first SRY-negative XX male Podenco dog with an almost complete female phenotype despite high basal and stimulated plasma testosterone concentrations. It is hypothesized that the clinical observations in this dog may have been caused by reduced and delayed Müllerian-inhibiting substance secretion and the absence of conversion of testosterone to dihydrotestosterone due to 5α-reductase deficiency.     

Development of a method for the identification, using the polymerase chain reaction, of Aspergillus fumigatus isolated from ostriches

Objective To develop a method for identifying DNA of Aspergillus fumigatus from ostriches, using the polymerase chain reaction (PCR). A fumigatus is the principal causative agent of avian aspergillosis.
Design A biochemical trial.
Sample population Twelve Aspergillus fumigatus isolates and three other Aspergillus species.
Procedure PCR primers that were based on the sequence of the alkaline protease gene from human isolates of A fumigatus were used.
Results We successfully tested the method on ostrich isolates from five states and showed that the test is specific for A fumigatus.
Conclusions In most cases the DNA sequence of A fumigatus isolates from ostriches is similar to that of human isolates. DNA sequences vary significantly among A fumigatus isolates, including those from affected ostriches in the same flock. The genetic variation may be used to trace aspergillus infections in ostrich flocks and determine if the disease is transmitted by contact with infected birds.