Riebold Tw

Comparison of lidocaine, xylazine, and lidocaine−xylazine for caudal epidural analgesia in cattle

OBJECTIVE To directly compare the time to onset and duration of analgesia produced by a lidocaine/xylazine combination with that produced by lidocaine and xylazine administered alone in the caudal epidural space of dairy cattle. Design   Prospective randomized experimental study. ANIMALS Nine adult (> 4 years of age) dairy cows (520-613 kg). METHODS Caudal epidural analgesia was produced in all cows with 2% lidocaine (0.22 mg kg-1; 5.5 mL 500 kg-1), 10% xylazine (0.05 mg kg-1 diluted to 5.5 mL 500 kg-1 with sterile water), and 2% lidocaine/10% xylazine (0.22 mg kg-1/0.05 mg kg-1; total volume of 5.7 mL 500 kg-1), at no earlier than weekly intervals in a Latin square design. Time to onset, duration and cranial spread of analgesia were recorded, as were degree of sedation, ataxia and ptyalism. RESULTS No significant difference (p > 0.05) was noted for time (mean ± SEM) of onset of analgesia between lidocaine (4.8 ± 1.0 minutes) and the lidocaine/xylazine combination (5.1 ± 0.9 minutes) but onset of analgesia following xylazine was significantly longer (11.7 ± 1.0 minutes) than either of the other two treatments. Lidocaine/xylazine (302.8 ± 11.0 minutes) produced analgesia of significantly longer duration than that of xylazine (252.9 ± 18.9 minutes) and both the lidocaine/xylazine combination and xylazine alone produced analgesia of significantly longer duration than that produced by lidocaine (81.8 ± 11.8 minutes). In all cattle, xylazine, administered either alone or with lidocaine, induced mild to moderate sedation and ataxia and cutaneous analgesia from the coccyx to T13. Mild ataxia was also present in those cattle receiving lidocaine alone. CONCLUSION The combination of xylazine and lidocaine produces analgesia of quicker onset and longer duration than xylazine administered alone and of longer duration than lidocaine administered alone. CLINICAL RELEVANCE Utilizing this combination, long-duration obstetrical and surgical procedures could commence relatively soon after epidural injection and could be completed without re-administration of anesthetic agents.

Prophylactic partial stylohyoidostectomy for horses with osteoarthropathy of the temporohyoid joint

Summary A technique of partial, unilateral, stylohyoidostectomy was developed for use in horses with chronic proliferative temporohyoid osteoarthrosis and ankylosis to prevent stress fractures of the skull. Partial stylohyoidostectomy may prevent fracture by eliminating forces on the skull resulting from movement of the tongue and larynx. Clinical, radiographic and histologic effects of unilateral (n=4) and bilateral (n=1) partial ostectomy performed in 5 horses were evaluated. Dysphagia was present for 1 week following unilateral, partial ostectomy but the horse that had a bilateral, partial ostectomy had residual prehension and mastication deficits when it was euthanatized 5 weeks after surgery. A pseudoarthrosis occurred between the cut ends of the stylohyoid bone. Unilateral, partial stylohyoidostectomy was easily performed and caused no permanent complications.

Monitoring Equine Anesthesia

Continued improvement in techniques used to assess the depth of anesthesia has made monitoring equine anesthesia more precise and, in turn, has made anesthesia safer. Techniques that are described include those that use the individual’s senses, monitoring equipment, and clinical judgment to assess the effects of the drugs on the cardiovascular, respiratory, and central nervous systems.

Effect of hind limb position on the craniocaudal length of the lumbosacral space in anesthetized dogs

OBJECTIVE To investigate whether rostral extension of the hind limbs increases the cranio-caudal dorsal interlaminar distance between the seventh lumbar vertebra and the sacral bone (LS distance) in sternally recumbent anesthetized dogs. STUDY DESIGN Prospective clinical study. ANIMALS Eighteen dogs (eight neutered males, three intact males, six spayed females, one intact female) of various breeds, weighing 4-34 kg and ranging in age from 1 to 13 years. METHODS Each dog was grouped by size: small (≤ 10 kg), medium (15-20 kg) or large (≥ 25 kg). Each dog was anesthetized and positioned in sternal recumbency. Computed tomography (CT) of the lumbosacral area was performed with the hind limbs resting on the stifle and the feet extended posteriorly, and then with the hind limbs extended rostrally. LS distance, craniocaudal dorsal interlaminar distance between sixth and seventh lumbar vertebra (L6-L7 distance), length of L7 vertebral body and lumbosacral angle (LS angle) were measured on a reconstructed mid-sagittal CT image from the two hind limb positions. The measurements from the two hind limb positions for the whole dog population and by size were compared using Students T tests. Diagnostic interpretation of the CT images was performed. RESULTS The length of L7 was taken as the reference value as it was not affected by hind limb position. LS distance, L6-L7 distance and LS angle were significantly higher when the hind limbs were extended rostrally in all three size groups. The CT images of ten dogs showed clinically undetected osteoarthrosis of the ileo- and lumbosacral area. CONCLUSIONS AND CLINICAL RELEVANCE Rostral extension of the hind limbs significantly increases LS and L6-L7 distance and LS angle even in dogs with clinically undetected osteoarthrosis of the ileo- and lumbosacral area, and may enhance the ease of lumbosacral epidural injection in sternally recumbent anesthetized dogs.

Cerebral injury from intracarotid injection in an alpaca (Vicugna pacos).

A mixture of ketamine, xylazine, and butorphanol was inadvertently injected into the right carotid artery of a 1-year-old alpaca. Injection was followed by a brief period of recumbency and seizure activity. The alpaca recovered, but was euthanatized 72 hr later because of development of progressive neurologic deficits. Pathologic findings were confined to the right cerebrum, meninges, thalamus, and hippocampus. Cerebrocortical edema with astrocytic reaction, perivascular hemorrhage and neutrophilic infiltration, and fibrinoid necrosis of vasculature within the meninges and thalamus were the most prominent lesions. Neuronal necrosis was mild. Astrocytic reaction within the right cerebral cortex was confirmed with immunohistochemistry for glial fibrillary acidic protein.

Cardiac-gated computed tomography angiography in three alpacas with complex congenital heart disease.

BACKGROUND The prevalence of congenital heart disease is higher in camelids than in other domestic species and complex defects, often involving the great vessels, are more frequently encountered in llamas and alpacas than in other species. Some of these complex defects can be difficult to accurately characterize via echocardiography, the most commonly used diagnostic imaging technique to evaluate the heart in veterinary patients. Contrast-enhanced, electrocardiogram (ECG)-gated computed tomography (CT) has proven utility for the evaluation of human patients with certain congenital heart defects, including those with conotruncal septation defects and other abnormalities involving the formation of the great vessels. METHODS Three alpaca crias, 4 days, 5 weeks and 14 months of age were clinically evaluated and subjected to a complete color-flow Doppler echocardiogram and a contrast-enhanced ECG-gated CT. RESULTS These alpacas exhibited a variety of clinical findings including lethargy, failure to thrive, exercise intolerance, heart murmur, and/or respiratory difficulty. All three crias were subsequently diagnosed with complex cardiac defects including pulmonary atresia with a ventricular septal defect (VSD), a truncus arteriosus with a large VSD, and a double outlet right ventricle with a large VSD and aortic hypoplasia. In each case, the diagnosis was confirmed by postmortem examination. CONCLUSION Color flow echocardiographic evaluation identified all of the intra-cardiac lesions and associated flow anomalies but contrast-enhanced ECG-gated CT permitted more accurate assessment of the morphology of the extracardiac structures and permitted a more precise determination of the exact nature and anatomy of the great vessels.