Influence of Dexamethasone on Some Reproductive Hormones and Uterine Progesterone Receptor Localization in Pregnant Yankasa Sheep in Semiarid Zones of Nigeria.

Dexamethasone is widely used in both veterinary and human medical practices. However, it seems to cause some deleterious effects on pregnancy probably by causing changes in the reproductive hormone levels and their corresponding receptor concentrations. This study investigated the effects of dexamethasone on these parameters. Twenty healthy adult Yankasa sheep comprising 18 ewes and 2 rams were used for this study. Pregnancies were achieved by natural mating after estrus synchronization. Dexamethasone was administered at 0.25 mg/kg body weight on days 1, 3, and 5 during first trimester; days 51, 53, and 55 during second trimester; and days 101, 103, and 105 during the third trimester. Blood samples were collected biweekly for hormonal assay. Uterine biopsies were harvested through caesarean section for immunohistochemical analysis. Results showed that dexamethasone significantly (p < 0.05) decreased progesterone concentrations and caused abortion in Yankasa sheep but had no significant (p > 0.05) effect on estrogen, while progesterone receptors (PR) were upregulated. The abortion could probably be due to decreased progesterone concentrations as a consequence of the adverse effects on placenta. The PR upregulation may be a compensatory mechanism to increase progesterone sensitivity. It was concluded that dexamethasone should not be used in advanced pregnancy in Yankasa sheep.

Effects of dexamethasone on progesterone and estrogen profiles and uterine progesterone receptor localization during pregnancy in Sahel goat in Semi-Arid region.

BACKGROUND: Despite the widespread use of dexamethasone in veterinary and human medicine, it is reported to cause some severe pregnancy related side effects like abortion in some animals. The mechanism of the response is not clear but seems to be related to interspecies and/or breed difference in response which may involve alterations in the concentrations of some reproductive hormones. METHODS: Twenty Sahel goats comprising 18 does and 2 bucks were used for this study. Pregnancies were achieved by natural mating after synchronization. Repeated dexamethasone injections were given at 0.25 mg/kg body weight. Blood samples were collected biweekly for hormonal assay. Uterine biopsies were harvested at days 28 and day 78 of gestation through caesarean section for immunohistochemical analysis using 3 pregnant does randomly selected from each group at each instant. Data were expressed as Means ± Standard Deviations and analyzed using statistical soft ware package, GraphPad Instant, version 3.0 (2003) and progesterone receptor (PR) were scored semi-quantitatively. RESULTS: Dexamethasone treatments had no significant (p > 0.05) effect on progesterone and estrogen concentrations in pregnant Sahel goats but up regulated PR from 2+ to 3+ in second trimester. CONCLUSION: As dexamethasone adverse effect on placenta is an established fact, the lack of effect on progesterone level in this study may be due to the fact that unlike other species whose progesterone production during pregnancy is placenta - dependent, in goats is corpus luteum - dependent. Consequently dexamethasone adverse effect on placenta reported in literatures did not influence progesterone levels during pregnancy in Sahel goat. The up regulation of progesterone receptor (PR) in Sahel goat gravid uterus is a beneficial effects and that dexamethasone can safely be used in corpus luteum - dependent progesterone secreting pregnant animal species like Sahel goat and camel. Therefore source of progesterone secretions during pregnancy should be considered in clinical application of dexamethasone in pregnancy.

Comparative studies on genital infections and antimicrobial susceptibility patterns of isolates from camels (Camelus dromedarius) and cows (Bos indicus) in Maiduguri, north-eastern Nigeria.

A total of 160 genitalia of Camels and cows were investigated in Maiduguri, north-eastern Nigeria to compare bacterial isolates and the antibacterial susceptibilities of some of the isolates. Streptococcus (Str.) pyogenes (31%), Escherichia (E.) coli (24%) and Staphylococcus (S.) aureus (20%) were the most common vaginal bacterial isolates in camels; while E. coli (73%), Str. pyogenes (18%) and S. aureus (11%) were the most frequent isolates in the cows. Of the 78 uterine isolates recovered in this study, E. coli was the most prominent in camels (8%) and cows (54%). The overall weight of genital infection in all camels and cows examined was highest (P < 0.05) with E. coli (79%), but there was no difference (P > 0.05) between vaginal and uterine bacterial isolates from camels and cows in this study. The Relative Risk (RR) for an infection of the vagina with E coli (3.04, 95% Confidence Interval (CI): 2.104 to 4.398, P < 0.0001) is more in cows compared to the camel, but the RR for vaginal infection with S. aureus and Str. pyogenes were lower in cows compared to Camels. The E. coli and S. aureus isolates were highly susceptible to the antimicrobial agents tested. Therefore effective management of reproductive disorders associated with these pathogens can be achieved with proper use of these antimicrobial agents in these animal species.

The prevalence of bovine venereal campylobacteriosis in cattle herds in the Lake Chad basin of Nigeria.

The prevalence of bovine venereal campylobacteriosis (BVC) was investigated in the Lake Chad basin of Nigeria. Preputial washings and cervico-vaginal mucus samples were obtained from 270 cattle presenting a history of abortion and lowered fertility, kept in traditional and institutional farms. All the samples investigated were cultured using standard bacteriological technique. Campylobacter fetus was isolated from six bulls and four cows. In all cattle sampled, the isolation rates were 2.2% for C. fetus subsp. venerealis and 1.5% for C. fetus subsp. fetus; the herd and within-herd prevalence rates for C. fetus were 22.2% and 3.4%, respectively, while the overall active infectivity rate was 3.7%. BVC probably contributes to lowered fertility and abortions found in cattle in the Lake Chad basin of Nigeria, associated more with C. fetus subsp. venerealis than C. fetus subsp. fetus.

The effect of vitamin C at varying times on physiological parameters in rabbits after xylazine anaesthesia.

The effects of vitamin C administration at varying time intervals on rectal temperature, respiratory rates, heart rates and sleeping time following xylazine anaesthesia was evaluated in rabbits. A total of 36 rabbits placed in six groups (A-F) with 6 animals per group each were used. Groups A and B were used as controls for vitamin C (120 mg/kg, oral) and xylazine (4 mg/kg, intramuscular) treatments, respectively, while groups C-F received vitamin C at four intervals prior to xylazine anaesthesia. The result of the study showed that vitamin C pre-medication prior to xylazine anaesthesia induced depression in respiratory and heart rates and a slight increase in rectal temperature. It also significantly increased sleeping time in rabbits (p<0.05). The lengthiest duration of sleep was observed among rabbits that received vitamin C 60 min prior to xylazine anaesthesia. Vitamin C administration 10 min prior to xylazine anaesthesia in rabbits induced a sleeping time three times the value compared to those animals that had received xylazine anaesthesia alone. However, the study did not observe a significant difference (p>0.05) in temperature between groups either before or after xylazine administration. It was concluded that vitamin C alters the clinical parameters as well as the sleeping time in rabbits under xylazine anaesthesia.

Beta-lactamase Escherichia coli and Staphylococcus aureus isolated from chickens in Nigeria.

The occurrence of beta-lactamase-producing Escherichia coli and Staphylococcus aureus in chickens was investigated. Specimens (n = 1,300) were collected from 400 chickens and were streaked on MacConkey agar plates. From each plate, presumptive growths of organisms were picked and streaked on eosin methylene blue and Baird-Parker agars, respectively. Typical colonies of E. coli and S. aureus with similar morphologies were identified by biochemical tests. Isolates were tested for beta-lactamase production and antimicrobial susceptibilities. Results indicated that 805 E. coli isolates from which 89 (11%) were beta-lactamase-positive and 660 S. aureus from which 58 (8.8%) were beta-lactamase-positive. Both isolates showed a high level of resistance to all twelve antibiotics screened. The increased prevalence of antibiotic resistance amongst bacterial organisms is undoubtedly correlated with the discovery and characterisation of multiple, transferrable resistance determinants, such as beta-lactamases, corresponding to their respective phenotypes. The implications of this for humans when handling and/or consuming chickens and chicken products contaminated with strains of such isolates, is a risk of transferrable multi-drug resistance and a failure of treatment. The results of our study indicated that beta-lactamase-producing E. coli and S. aureus are prevalent in chickens in Nigeria.