QUANTITATIVE ULTRASONOGRAPHY FOR ASSESSMENT OF BONE MINERAL DENSITY IN THE CANINE RADIUS AND TIBIA

Quantitative ultrasound allows noninvasive assessment of cortical bone density. Potential applications include monitoring of fracture healing, rehabilitation, and skeletal diseases. The objectives of this study were to determine the three most accessible portals to obtain speed of sound measurements of the radius and tibia with an Omnisense multisite quantitative ultrasound device and to determine probe-dependent intra- and interoperator variability for speed of sound measurements of the radius and tibia in six healthy hounds. The radius was most accessible at the cranial proximal metaphysis, the cranial middiaphysis, and medial distal metaphysis. Speed of sound measurements were possible at these sites on the radius with acceptable intra- and interoperator variation (1.6–4.6%). Measurements differed significantly when performed with different probes at the cranial proximal radial metaphysis. The tibia was most accessible at the cranial proximal metaphysis, the medial middiaphysis, and medial distal metaphysis. The medial middiaphyseal and mediodistal tibial sites allowed measurements with lowest intra- and interoperator variation (<3.5%). A smaller probe allowed tibial measurements with lowest interoperator variation. Measurements did not differ significantly at each tibial site when different probes were used. Measurements did not differ significantly between observers when measuring with the same probe at each specific site on radius and tibia. A medium-size probe allowed for most time-efficient measurements and the least number of failed measurements on the radius and tibia. Speed of sound can be consistently measured by different observers on the radius and tibia in healthy hounds.     

The effect of anesthesia and surgery on heart rate variability in dogs

Heart rate variability (HRV) may be useful for objective assessment of stress and pain in animals. The objective of this study was to describe the effect of anesthesia and surgery on HRV in dogs. We hypothesized that surgery would decrease HRV to a greater degree and for a longer duration than anesthesia alone. Four healthy male dogs (29 ± 2 kg) were instrumented for ambulatory ECG monitoring. Continuous ECG data was obtained for 1 day prior to, and 6 days following anesthesia alone (ANES) or anesthesia plus unilateral stifle arthrotomy (ANSX). The anesthetic protocol included xylazine (0.5 mg kg^–1 IM), morphine (0.5 mg kg^–1 IM), atropine (0.04 mg kg^–1 IM), thiopental (10 mg kg^–1 IV) and isoflurane in oxygen. A single dose of morphine (0.5 mg kg^–1 IM) was administered at extubation. Time domain analysis of HRV was performed on 5 minutes epochs of artefact‐ and arrhythmia‐free ECG data obtained at 12 noon and 12 midnight on each of the seven experimental days. Mean RR interval, standard deviation of normal R‐R intervals (SDNN), and the standard deviation of successive differences in RR intervals (SDSD) were compared to baseline for ANES and ANSX. Pain scores obtained during the day were also evaluated. Significance was set at p < 0.01. There were no differences between groups for any baseline data. Mean RR interval did not differ from baseline on days 1–6 in ANES or ANSX. SDNN and SDSD values at noon were not different from baseline on days 1–6 in ANES or ANSX. At midnight on days 1 and 2, SDNN was significantly decreased from baseline in ANSX, and on day 1 a significant difference between groups existed. ANSX values of SDSD at midnight were significantly decreased from baseline and ANES on day 1. Pain scores for ANSX were significantly greater than baseline on days 1–3, and different from ANES on days 1–5. These results suggest that HRV is decreased following anesthesia plus surgery, and that changes in HRV may be associated with pain.     

A comparison of conservative treatment and fenestration for thoracolumbar intervertebral disc disease in the dog

Many dogs will recover after a thoracolumbar disc protrusion whether they are treated conservatively or surgically. Two statistically similar groups of dogs submitted to the Department of Surgery, Royal Veterinary College (RVC) and to the Department of Surgery, University of Glasgow Veterinary School (UGVS) were reviewed. At the RVC an aggressive surgical policy was adopted and at the UGVS a conservative regime was followed. A comparison has been made between the two groups to evaluate the advantages of each regime. This comparison has provided the basis for a treatment protocol for cases of thoracolumbar intervertebral disc disease in the dog.     

Specific microbial responses to herbicides*

Examples from the literature and from the authors’own laboratory demonstrate that herbicides can exert adverse effects on the soil micro-flora, depending on concentration, though often at higher rates than the herbicidal dose. Examples refer to changes in microbial growth (asulam, linuron, paraquat) and equilibrium (metoxuron), respiration and nitrification in samples from field experiments (linuron, simazine) and laboratory experiments (bentazone, glyphosate, barban, etc.), enzyme activities (urease, phosphatase; barban, chlorpropham, linuron) and the decay of sprayed vegetation (glyphosate, paraquat).