Use of an aiming device for application of a type-II (bilateral) external fixator to a fractured tibia of a dog

An aiming device was used to guide insertion of fixation pins in a type-II (bilateral) external fixator stabilizing an open canine tibial fracture. This device, designed by the Swiss AO group, has multiple applications in orthopedic surgery, because it accurately locates the exit point of a pin or drill hole on the far side of a bone or fractured bone fragment. When used with the type-II external fixator, it greatly facilitates pin placement by ensuring that, as a pin emerges from the bone, it is in line with the second clamp on the opposite connecting bar.     

Resistance monitoring of Heliothis virescens to pyramided cotton varieties with a hydrateable, artificial cotton leaf bioassay

Proof of concept was demonstrated for a practical, off-the-shelf bioassay to monitor for tobacco budworm resistance to pyramided Bt cotton using plant filtrates. The bioassay was based on a previously described feeding disruption test using hydrateable artificial diet containing a blue indicator dye, a diagnostic dose of insecticide and novel assay architecture. Using neonate larvae from a Bt-susceptible, laboratory reared tobacco budworm strain, a diagnostic dose for Bollgard II and WideStrike cotton was obtained that limited neonate blue fecal production to 0-2 pellets in 24 h (Bt-resistant larvae produced >2 fecal pellets). The bioassay was tested with three different field populations of tobacco budworm collected from tobacco in central North Carolina (USA) and shown to accurately diagnose susceptibility to Bt. The diagnostic doses were also successfully evaluated with two Bt-resistant, laboratory reared tobacco budworm strains. Shelf life studies showed the assay could be stored for at least 6 months at room temperature (longer storage times were not studied). The application of the bioassay as an easy to use monitoring tool is discussed.     

Evaluation of wraps covering the distal aspect of pelvic limbs for prevention of bacterial strike-through in an ex vivo canine model

Objective— To determine differences in bacterial strike-through for materials commonly used to cover the distal aspect of the pelvic limb during operative site preparation.
Study Design— Randomized block design; ex vivo model.
Animals— Canine cadaveric pelvic limbs (n=40).
Methods— Pelvic limbs (n=40) were randomly assigned to 4 treatment groups: Group 1=Vetrap^™+sterile Coban^™; Group 2=latex glove+Vetrap^™+sterile Coban^™; Group 3=latex glove+Vetrap^™+sterile Coban^™+sterile latex glove+sterile Coban^™; and Group 4=latex glove+Vetrap^™+sterile disposable drape+sterile Coban^™. Limbs were contaminated with a standardized bacterial solution and routinely prepared using the assigned distal leg wrap. Bandages were fluid challenged with a saline (0.9% NaCl) solution-soaked laparotomy sponge for 30 seconds. The wrap surface was sampled for microbial culture before surgical preparation, immediately after, and 60 minutes after applying a sterile leg wrap.
Results— Bacterial growth occurred in all Group 1 cultures, 90% of Group 2 cultures, and none of the Group 3 and 4 cultures, 60 minutes after applying the sterile wrap.
Conclusion— A distal leg wrap of Vetrap^™+sterile Coban^™ is not effective in preventing bacterial strike-through.
Clinical Relevance— If similar results occur in the live animal, then a sterile impermeable barrier must be incorporated into the distal leg wrap to prevent bacterial strike-through.     

An In Vitro Comparison of Hollow Ground and Trocar Points on Threaded Positive-Profile External Skeletal Fixation Pins in Canine Cadaveric Bone

OBJECTIVE: To compare the microstructural damage created in bone by pins with lathe-cut and rolled-on threads, and to determine the peak tip temperature and damage created by positive-profile external fixator pins with either hollow ground (HG) or trocar (T) tips during insertion. STUDY DESIGN: An acute, in vitro biomechanical evaluation. SAMPLE POPULATION: Twenty-seven canine tibiae. METHODS: Lathe-cut thread design with T point (LT-T), rolled-on thread design with T point (RT-T), and rolled-on thread design with HG point (RT-HG) pins were evaluated. Twenty pins of each type were inserted under constant drilling pressure into 12 canine tibiae (12 diaphyseal and 8 metaphyseal sites per pin type). Peak pin tip temperature, drilling energy, end-insertional pin torque, and pullout force were measured for each pin. For the histologic study, five pins of each type were inserted into cortical and cancellous sites in 15 additional tibiae. Entry and exit damage, and thread quality were assessed from 100 micron histologic sections by using computer-interfaced videomicroscopy. RESULTS: T-tipped pins reached higher tip temperature in both diaphyseal and metaphyseal bone compared with HG-tipped pins. RT-T pins had higher pullout strength (diaphyseal) and end-insertional torque compared with other combinations. No differences in drilling energy or insertional bone damage was found between the three pin types (P < .05). CONCLUSIONS: T-tipped pins mechanically outperformed HG-tipped pins. Pin tip and thread design did not significantly influence the degree of insertional bone damage. CLINICAL RELEVANCE: T-tipped pins may provide the best compromise between thermal damage and interface friction for maximizing performance of threaded external fixator pins.     

Expression of MHC-I and -II in Uterine Tissue from Early Pregnant Bitches

The aim of the study was to investigate the expression of major histocompatibility complex (MHC)-I and -II in uterine tissues from pregnant and non-pregnant bitches, taken at different time periods after mating. The pregnant bitches were ovariohysterectomized during the pre-implantation (group 1, n = 4), implantation (group 2, n = 7) and placentation stage (group 3, n = 7). Non-pregnant animals in diestrus served as controls (group 4, n = 7). The expression of MHC- I and -II in salpinx, apex, middle horn, corpus uteri and at implantation sites was investigated by immunohistochemistry as well as qualitative and quantitative RT-PCR; MHC-I mRNA was detected in all tissues and with quantitative RT-PCR, and no significant changes were detected until placentation. Immunohistologically, at the apex and corpus site, the average number of MHC-II positive cells increased from the pre-implantation to the post-implantation stage (apex: 1.54 ± 1.21 to 3.82 ± 2.93; corpus: 1.62 ± 1.9 to 5.04 ± 4.95; p < 0.05). The greatest numbers of MHC-II positive cells were observed at placentation sites (6.64 ± 5.9). In parallel, a marked increase in the relative mRNA expression of MHC-II in uterine tissues was assessed from the pre-implantation to the placentation stage (relative to Glycerinaldehyd-3-phosphate-Dehydrogenase (GAPDH): 6.9 ± 9.5, 8.4 ± 5.8, p > 0.05). Immunohistologically, in the salpinx, significantly greater numbers of MHC-II positive cells were found in the tissues of pregnant animals than in the control group (p < 0.05). It is proposed that the increase in MHC-II is pregnancy-related, even though the impact on maintenance of canine pregnancy is still unclear.     

Epidemiological studies of pig diseases: 1. Use of French protocols for risk factor assessment to predict the health status of Australian herds

Objective To determine in Australian pig herds the accuracy of French protocols for risk factor assessment.
Procedure Data on health indicators and risk factors were collected for three syndromes, 'pre-weaning diarrhoea', 'post-weaning diarrhoea' and 'respiratory problems', using the French protocols. The protocols were used on 118 occasions in 32 Western Australian pig herds during 3 years (1988 to 1991).
Results There was a wide variation in pre-weaning performance, for example growth rate was 107 to 273 g/day (< 200 g/day in 33% of herds). Respiratory lesions at weaning were associated with poor pre-weaning performance. Post-weaning (21 days after weaning) growth rate was 114 to 408 g/day (< 250 g/day in 54% of herds). In the grower herds, 91% of herds had pneumonia, and growth rate was 439 to 625 g/day (< 550 g/day in 54% of herds). Pleurisy as well as pneumonia was associated with reduced growth rate. The risk factor most closely associated with respiratory health status was air volume per pig.
Conclusion Risk factors were most accurate at predicting the health status in post-weaning problems. A weaning weight of at least 7.9 kg and weaning age of 30 days optimised weaner performance. Stocking densities and shed designs providing at least 3 m³ air volume and 0.6 m² floor space per pig throughout the growing phase should be considered for an improved respiratory health status. Australian pig sheds often do not provide a satisfactory environment for optimum health. The technique of risk factor assessment as an aid to the maintenance of health in pig herds is applicable in Australia, but further research is necessary to determine the most important Australian risk factors.