Ultrasonographical identification of the superficial circumflex iliac artery as a landmark for location of the femoral nerve in dogs

Objective

To investigate the utility of identifying the superficial circumflex iliac artery (SCIA) via ultrasound as an anatomical landmark for ultrasound-guided femoral nerve block.

Age-related changes in percentage of fiber types and mean fiber diameters of the ovine quadriceps muscles.

Mean fiber diameters and percentages of each fiber type of the vastus lateralis, vastus medialis, rectus femoris, and vastus intermedius muscles from 15 sheep, ranging from 1 day to 5 years of age, were determined. Myosin adenosine triphosphatase and nicotinamide adenine dinucleotide-tetrazolium reductase stained sections were used. The vastus lateralis, vastus medialis, and rectus femoris contained 3 fiber types (I, IIA, and IIB). The vastus intermedius was composed almost entirely of type I fibers. From birth to 5 years of age, mean fiber diameters of type I fibers increased from 15.8 to 47.0 micron in the vastus lateralis, 15.6 to 50.7 micron in the vastus medialis, 17.5 to 46.5 micron in the rectus femoris, and 26.7 to 51.8 micron in the vastus intermedius. Means of fiber diameters of type II fibers increased from 16.1 to 44.6 micron in the vastus lateralis, 19.8 to 44.0 micron in the vastus medialis, and 17.0 to 44.5 micron in the rectus femoris. The percentage of type II fibers in the vastus lateralis, vastus medialis, and rectus femoris decreased from 85% to 90% at birth to approximately 72% at 5 years of age. The vastus intermedius consisted of only type I fibers in sheep 2 years and older.     

Normal values for radial,peroneal and tibial motor nerve conduction velocities in adult sheep,with comparison to adult dogs

A technique for measuring motor nerve conduction velocities (NCV) in sheep was developed using 15 clinically normal ewes. Mean ±SD values were determined for the radial (76.3±12.5 m/s), peroneal (103.9±12.7 m/s), and tibial (98.6±13.1 m/s) nerves. The recording needle electrode was located in the extensor carpi radialis, tibialis cranialis, and gastrocnemius muscles, respectively. Latencies, amplitudes and durations of the proximal and distal evoked compound muscle action potentials are given. To investigate further the unexpectedly high NCVs calculated for the peroneal and tibial nerves, analogous stimulating and recording electrode sites were used in 7 clinically normal dogs. The corresponding canine peroneal (88.1±8.3 m/s) and tibial (89.2±12.4 m/s) NCVs were higher than the standard sciatic-tibial NCV recorded from the interosseous Myelinated nerve fiber diameters were measured on semithin transverse sections of peroneal and tibial nerve specimens taken from a clinically normal ewe and bitch. A possible explanation for the relative species difference in the proximal peroneal and tibial NCV values is the presence of fibers in both the peroneal and tibial nerves of the sheep which were as much as 3 wider than the largest fibers found in the dog.     

Conduction velocities and myelinated fiber diameter spectra of the infraorbital and palpebral nerves of the dog

Maximum conduction velocities of compound-action potentials of the infraorbital (ION) and palpebral (PN) nerves were determined by averaging potentials evoked and recorded through subcutaneous needle electrodes. The specificity of the stimulating and recording sites was verified by recording before and after cutting the nerves. Conduction times for orthodromically and antidromically conducted potentials of the ION were essentially the same. The unipolarly recorded antidromic compound-action potentials of the ION were of higher peak-to-peak amplitude and were more reliably recorded than were the bipolarly recorded orthodromic action potentials. Areas of cutaneous innervation were not found for the PN. Neuromuscular blockade eliminated the volume-conducted muscle action potentials that were recorded after PN stimulation, allowing triphasic nerve action potentials to be recorded unobscured. Mean conduction velocities were: ION = 83.9 +/- 3.5 m/s; PN = 56.4 +/- 2.8 m/s. Distributions of the external diameters of myelinated fibers within the ION and the PN were determined.     

Examination of nasopharyngeal and tracheal somatosensory evoked potential recordings in dogs

OBJECTIVE: To investigate the value of nasopharyngeal and tracheal recordings of somatosensory evoked potentials (SSEP) in anesthetized dogs. ANIMALS: 10 healthy mixed-breed dogs (5 males and 5 females). PROCEDURE: Square-ware electrical stimuli (50 microseconds duration, 4Hz) were delivered through bipolar surface electrodes to the median nerve of the right forelimb with 7 to 12 mA constant current. The SSEP were recorded with soft electrodes placed on the epipharynx and dorsal wall of the trachea, respectively. Traditional scalp and neck recordings of SSEP were also performed, using SC-inserted needle electrodes. The potentials recorded dorsally and ventrally from the neuraxis were compared to assess the application of these signals for intraoperative neurophysiologic monitoring. RESULTS: Electrical stimulation of the median nerve resulted in multiphasic potentials recorded from all 4 recording sites. Latency and phase shifts were observed between the far-field potentials placed ventrally and dorsally from the neuraxis. CONCLUSIONS AND CLINICAL RELEVANCE: Potentials recorded with nasopharyngeal and tracheal electrodes are regarded suitable for intraoperative neurophysiologic monitoring in anesthized dogs.     

Repetitive stimulation of the common peroneal nerve as a diagnostic aid for botulism in foals

Background: Botulism is a potentially fatal paralytic disorder for which definitive diagnosis is difficult. Objectives: To determine if repetitive stimulation of the common peroneal nerve will aid in the diagnosis of botulism in foals. Animals: Four control and 3 affected foals. Methods: Validation of the test in healthy foals for its comparison in foals with suspected botulism. Controls were anesthetized and affected foals were sedated to avoid risks of anesthesia. The common peroneal nerve was chosen for its superficial location and easy access. Stimulating electrodes were placed along the common peroneal nerve. For recording, the active and reference electrodes were positioned over the midpoint and distal end of the extensor digitorum longus muscle, respectively. Repeated supramaximal stimulation of the nerve was performed utilizing a range of frequencies (1–50 Hz). Data analysis consisted of measuring the amplitude and area under the curve for each M wave and converting these values into percentages of decrement or increment based on the comparison of subsequent potentials to the initial one (baseline) within each set. Results: A decremental response was seen at all frequencies in control foals. Decremental responses also were observed in affected foals at low frequencies. An incremental response was seen in all affected foals at 50 Hz. Conclusions and Clinical Importance: Decreased baseline M wave amplitudes with incremental responses at high rates are supportive of botulism. Repetitive nerve stimulation is a safe, simple, fast, and noninvasive technique that can aid in the diagnosis of suspected botulism in foals.     

The feline dorsal nerve of the penis arises from the deep perineal nerve and not the sensory afferent branch

The cat has been used extensively as an animal model for urogenital studies involving the pudendal nerve. However, discrepancies persist in the literature regarding the origin of the dorsal nerve of the penis (DNP). This study used gross dissections and serial histological cross sections to demonstrate that the DNP arises from the deep perineal nerve and not the sensory afferent branch as previously reported. This finding indicates a better than previously appreciated neuroanatomical homology between the cat and human.     

Compound-action potentials of myelinated fibers in the saphenous nerve of the dog: in situ electrophysiologic and behavioral studies

Compound-action potentials (CAP) were recorded directly from the surface of fascicles of the distal portion of the saphenous nerve (SN) of dogs in situ. Potentials were evoked through needle electrodes and were recorded through bipolar stainless steel electrodes. Stimuli of 10-microseconds duration and of 0.4 +/- 0.15-mA amplitude evoked a monophasic CAP. Sensory conduction velocities of afferent fibers, the action potentials of which contributed to this evoked compound potential, ranged from 62.4 +/- 2.8 m/s for the most rapidly conducting fibers to 30.5 +/- 2.4 m/s for the least rapidly conducting fibers. Stimuli of 25-microseconds duration and of 2.2 +/- 0.8-mA amplitude evoked a second, longer latency CAP in addition to the first CAP. Sensory conduction velocities of afferent fibers, the action potentials of which contributed to this evoked compound potential, ranged from 20.4 +/- 2.9 m/s for the most rapidly conducting fibers to 13.7 +/- 1.0 m/s for the least rapidly conducting fibers. Low-amplitude, negative peaks were recorded between the first and second major potentials elicited by the longer duration stimuli. Stimuli of still longer duration and higher currents induced contractions of the caudal part of the sartorius muscle by current spread in 9 of 12 dogs. In 3 dogs, a third monophasic CAP was evoked, having a maximal conduction velocity of 1.7 +/- 0.2 m/s. After section of the distal portion of the SN on one side in each of 2 dogs, an absence of signs of sensory deficit was found on clinical neurologic examination. The area of cutaneous innervation of the cranial branch of the distal portion of the SN was determined electrophysiologically.     

Fine structure of the retino-optic nerve junction in dogs

In most mammals, the optic nerve fibers are myelinated in its extraocular part (EON) but not in its intraocular part (ION) and also in the retina. Transitional zone from the myelinated to unmyelinated optic nerve usually lies in the central part to the lamina cribrosa. It has been known that dogs contain exceptionally myelinated fibers in ION by light microscopy. The aim of this study was to investigate electron microscopically the retino-optic nerve junction in dogs and re-evaluate the barrier to migration of oligodendroblasts into ION. Fourteen adult dogs were used. EON was largely myelinated. In ION the percentage of myelinated fibers decreased gradually toward the retina. A narrow area of ION adjoining the retina was completely unmyelinated. In most mammalian optic nerves, oligodendrocytes are not found in ION. It has been suggested that oligodendroblasts are prevented from migrating from EON into ION; that is to say, there is a barrier to migration of oligodendroblasts. The lamina cribrosa, a dense meshwork of fibrous astrocytic processes, and a defect in the blood optic nerve barrier have been proposed as a candidate for the barrier to migration. Our results suggest, however, that these factors, at least in dogs, would be not involved in the formation of a barrier to migration of oligodendroblasts.     

Tumours involving the nerve sheaths of the forelimb in dogs

Nerve sheath tumours were diagnosed in 10 dogs over a three-year period. The age at presentation ranged from three to 12 years (mean 6-3 years) and the sexes were equally represented. All the dogs were of medium to large breeds. The cases were assigned to two distinct clinical groups, which corresponded with the location of the neoplasia. One group presented as a chronic progressive, unilateral forelimb lameness; these dogs had peripherally located tumours. The other group had an acute onset of signs associated with spinal cord compression without previous forelimb signs. These were associated with tumours at the level of the spinal nerve roots.     

Effect of age on sensory nerve conduction velocity in the horse

This study aimed to establish a clinically reproducible method of evaluation of sensory nerve conduction in the horse and to provide reference values in a group of normal horses. Age-related changes in the sensory nerve conduction velocity were of particular interest. Sensory nerve conduction was performed in the lateral palmar nerve. The results revealed an increase in velocity over the first year of life and a subsequent decrease in velocity in older horses. The effect of age must be considered if results from horses in which peripheral nerve disease is suspected are to be interpreted correctly. The results reflect similar findings in man and other domestic species.     

Contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the swallowing process in dogs

The separate contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the innervation of the pharyngeal muscles were studied first in 10 canine cadavers by dissection of the pharyngeal plexus and the pharyngeal muscles. In 10 other dogs, the parent trunks and 1st division of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve were electrically stimulated. The evoked stimulation potentials were recorded from the stylopharyngeal, hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. One of the parent trunks was then transected, and the effects on the swallowing process were observed clinically and by contrast videofluorography. Denervation potentials resulting from nerve transection were recorded in the soft palate, the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. The pharyngeal plexus was composed of branches originating from the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve. In most dogs, the pharyngeal muscles and the soft palate were innervated ipsilaterally by both nerves. The swallowing process was more severely disturbed after bilateral transection of the pharyngeal branch of the vagus nerve than after bilateral transection of the glossopharyngeal nerve.     

Feasibility and repeatability of thermal quantitative sensory testing in normal dogs and dogs with hind limb osteoarthritis-associated pain

The objectives of this study were to determine whether thermal quantitative sensory testing (QST) can be performed in client-owned dogs, is repeatable and whether QST differs between normal dogs and dogs with hind limb osteoarthritis (OA). This clinical, prospective, observational study used clinically normal dogs (n = 23) and dogs with OA-associated hind limb pain (n = 9). Thermal QST was performed in standing dogs using a high-powered light source delivered by a previously validated system. Dogs were tested on two occasions, 2 weeks apart. Five tests were performed on each hind limb at each time point. Repeated measures analysis of variance was used to evaluate the effects of leg, time point and OA/normal status on thermal threshold latencies (TTL). Additionally, paired t tests were used to compare the TTL of left and right limbs within groups and between time points.Thermal thresholds were successfully measured in 32 client-owned dogs without prior training. TTL were significantly different between normal and OA dogs (P = 0.012). There was no difference between limbs (P = 0.744) or time periods (P = 0.572), when analyzed by repeated measures analysis of variance, and no interactions between group and limb, visit and limb, or visit and group. In conclusion, thermal thresholds can be measured in client owned dogs with no prior training and are repeatable from week to week. Further data are required to determine if OA results in thermal hypoalgesia as measured at the distal hind limb and whether this is an indication of central sensitization.     

日粮纤维与猪肠道健康的相关性研究与应用

在生猪产能恢复中,需要特别关注猪只肠道健康问题.很多营养素与猪的肠道健康密切相关,其中日粮纤维就是影响猪只肠道健康的重要营养素之一.日粮纤维在调节猪肠道微生态环境方面表现出异常活跃的营养学功能.日粮中适宜的纤维水平可改善猪肠道微生物种群多样性,调节菌群结构组成,维持猪肠道微生态平衡,提高饲料转化率,具有促进猪只的生长发...