Effect of feeding on plasma antibiotic concentrations in Greyhounds given ampicillin and amoxycillin by mouth

In a cross-over study, six Greyhounds were dosed by mouth with ampicillin and amoxycillin at 20 mg/kg, using three different feeding regimens (no food, canned food prior to dosing, and dry food ad lib ) with each drug. Antibiotic levels in plasma were determined by microbiological assay at intervals after dosing.
Plasma ampicillin concentrations tended to be lower in fed than in starved Greyhounds, but amoxycillin levels were relatively unaffected by feeding. In starved Greyhounds, ampicillin gave higher early levels than amoxycillin.     

Duration of Mycoplasma hyopneumoniae Infection in Gnotobiotic Pigs

Sixteen gnotobiotic pigs raised in flexible plastic isolators (four pigs per isolator) were inoculated with a culture of Mycoplasma hyopneumoniae. One pig was killed and underwent necropsy at weekly intervals for the following 16 weeks. Macroscopic lesions were observed in the lungs of 13 of 16 pigs and microscopic lesions were found in 14 of 16 pigs. Mycoplasma hyopneumoniae was cultured from the trachea or lungs from 10 of the 16 pigs. Scanning electron microscope studies showed areas of damage to the cilia, collections, of leucocytes and mucus, and mycoplasma in the trachea as well as the bronchi. These conditions were found in all the pigs seen at necropsy from nine to 16 weeks postinoculation and there was no evidence of noticeable regression or recovery during this 16 week period.     

Further investigation of lead exposure as a potential threatening process for a scavenging marsupial species

There is a growing recognition of the harmful effects of lead exposure on avian and mammalian scavengers. This can lead to both lethal and non-lethal effects which may negatively impact wildlife populations. Our objective was to assess medium-term lead exposure in wild Tasmanian devils (Sarcophilus harrisii). Frozen liver samples (n = 41), opportunistically collected in 2017–2022, were analysed using inductively coupled plasma mass spectrometry (ICP-MS) to determine liver lead concentrations. These results were then used to calculate the proportion of animals with elevated lead levels (>5 mg/kg dry weight) and examine the role of explanatory variables that may have influenced the results. The majority of samples analysed were from the south-east corner of Tasmania, within 50 km of Hobart. No Tasmanian devil samples were found to have elevated lead levels. The median liver lead concentration was 0.17 mg/kg (range 0.05–1.32 mg/kg). Female devils were found to have significantly higher liver lead concentrations than males (P = 0.013), which was likely related to lactation, but other variables (age, location, body mass) were not significant. These results suggest that wild Tasmanian devil populations currently show minimal medium-term evidence of exposure to lead pollution, although samples were concentrated in peri-urban areas. The results provide a baseline level which can be used to assess the impact of any future changes in lead use in Tasmania. Furthermore, these data can be used as a comparison for lead exposure studies in other mammalian scavengers, including other carnivorous marsupial species.     

Pharmacokinetics of cephalexin in cats after oral administration of the antibiotic in tablet and paste preparations

Objective To determine the bioequivalence of a paste formulation of cephalexin with that of the tablet form.
Design A two-way cross-over study.
Animals Ten adult cats of mixed breed.
Procedure The cats, randomly allocated to two groups, received either the paste preparation or the tablet orally at 12-hour intervals for 48 h before a 12-hour blood collection period. Two weeks later the treatments were reversed and the blood sampling repeated. The serum concentrations of the antibiotic were determined. The pharmacokinetic factors were analysed using a computer.
Results There were no significant differences between the peak concentration of cephalexin, or the other pharmacokinetic factors obtained from the tablet and paste formulations. The serum profiles of cephalexin following four 12-hourly doses of each formulation were similar with the peak serum values occurring at approximately 2 h after administration.
Conclusion The paste formulation and the tablet form are bioequivalent.     

The effects of antigenic competition on the efficacy of multivalent footrot vaccines

SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins.     

Preliminary Trial: Motility Comparisons of a Unique Freezing Technology (UFT) to Liquid Nitrogen Mist Methodology for Cryopreservation of Porcine Spermatozoa

The motility outcomes of boar semen frozen with newly developed freezing techniques using a new unique freezing technology (UFT) compared with traditional liquid nitrogen methodology were investigated with the intent of improving current fertility outcomes using semen. The UFT is an electronically controlled cooling chamber that houses an organic fluid bath that can be maintained at temperatures below 0 degrees C without solidifying to freeze samples. Four ejaculates from four different boars were collected for this trial. Samples were handled consistently during the pre- and post-freeze processing. From each ejaculate, samples were separated into eight cryopreservation treatment groups, six UFT variations and two control liquid nitrogen groups, immediately before freezing, in replicates of two. After the initial cryopreservation was complete, all samples were stored in liquid nitrogen for at least 48 h. Post-thaw motilities and original motility return percentages were assessed on a random, individual-sample basis. After the initial evaluations, samples from two boars were recollected and frozen using the UFT for breeding purposes. Four sows were bred with the UFT frozen semen to confirm fertility capability. When assessing the individual UFT techniques, all of six UFT techniques had improved post-thaw motilities. However, treatments F (micro = 29%, return micro = 37%) and J (micro = 27%, return micro = 34%) showed the highest statistical improvement for post-thaw (p < 0.05) and original motility percent returns (p < 0.05) when compared with either the control cryo-tube (micro = 15%, return micro = 19%) or straw groups (micro = 12%, return micro = 16%). The UFT semen had a 50% conception rate, with an average of seven piglets from the sows that farrowed. Our preliminary data suggest a higher motility return with a slower pre-freeze phase below the freezing point before the acceleration to liquid nitrogen temperatures. The preliminary data suggest that the UFT could be utilized as a potential cryopreservation option for boar semen.     

Gradual Occlusion of Extrahepatic Portosystemic Shunts in Dogs and Cats Using the Ameroid Constrictor

Gradual occlusion of the splenic vein, using a specialized device (ameroid constrictor), was evaluated experimentally in three normal beagle dogs. Splenoportograms were used to verify that total occlusion of the splenic vein had occurred in all dogs within 4 to 5 weeks after application of the device. The ameroid constrictor (AC) was also evaluated as a method of gradual vascular occlusion in 12 dogs and two cats with single, extrahepatic, portosystemic shunts (PSS). Serum bile acid (SBA) concentrations were measured and portal scintigraphy (PS) was performed on all 14 animals preoperatively and 10, 20, 30, and 60 days postoperatively. Two dogs (14%) died from portal hypertension in the early postoperative period. One dog and one cat developed multiple acquired PSS, confirmed by mesenteric portography 90 days after the operation. Portal scintigraphy confirmed total occlusion of the primary shunt in the other 10 animals. Shunt fractions (SF), as measured by PS on postoperative days 30 and 60, declined significantly from preoperative values. Significant decreases were noted between preoperative and postoperative values for preprandial SBA on postoperative day 60 and for postprandial SBA on postoperative day 30. SBA concentrations did not correlate with SF. Based on this study, gradual vascular occlusion using the AC is recommended as a method for treatment of single, extrahepatic, PSS.     

Pharmacokinetics of gentamicin after intravenous and subcutaneous injection in obese cats

Six adult domestic shorthair obese cats were given 3-mg/kg gentamicin sulfate by rapid i.v. and by s.c. injection in a cross-over design. The plasma concentration-time data were analyzed using statistical moment theory with no assumption of a specific compartmental model. Means +/- SD for the half-life, which was calculated from the terminal slope of the log concentration-time curve, were 1.37 +/- 0.24 and 1.24 +/- 0.22 h following i.v. and s.c. injection, respectively. The apparent volume of distribution at steady state was 118.55 +/- 19.83 ml/kg, and total body clearance was 1.07 +/- 0.25 ml/kg/min. Bioavailability was 83.58 +/- 14.83% after s.c. administration. The calculated s.c. dose in obese cats to produce an average steady-state concentration of 4 micrograms/ml is 2.5 mg/kg every 8 h compared to 3 mg/kg in normal-weight cats.