Epaxial Research Articles

An Investigation Into the Short-Term Effects of Photobiomodulation on the Mechanical Nociceptive Thresholds of M. Longissimus and M. Gluteus Medius, in Relation to Muscle Firing Rate in Horses at Three Different Gaits

Back pain is a common condition in horses, yet despite this, quantitative assessments of the efficacy of treatment are scarce. Mechanical nociceptive thresholds (MNTs) and acoustic myography (AMG) recordings were obtained, both preinterventionand postintervention, from the left and right epaxial muscles in eight healthy general riding horses (mean age 17 ± 6 yrs). Using an algometer, MNT readings were taken at each of the 6 preselected points along the thoracolumbar M. longissimus and M. gluteus medius region. AMG recordings of the M. longissimus and M. gluteus medius were taken while walking, trotting, and cantering on a left or right hand 20m circle on a longe, on a waxed sand surface in an indoor arena. Horses were then treated using a class 1 laser. Therapy was applied for 1 minute at 1000 Hz to the same preselected points from which MNT measurements had previously been taken. Measurements were subsequently taken 1 hour and 24 hours post-treatment for MNT reading, and only 24 hours after for AMG measurements. No significant effect of treatment was noted for the MNTs. The AMG results were analyzed in terms of their temporal summation (T-score), where statistically significant improvements in the T-scores for M. longissimus and M. gluteus medius were noted for the different gaits. It is concluded that cold laser therapy has a positive effect on horse muscles that reveals a change in their firing frequency that is commensurate with changes seen with analgesia in subjects experiencing pain.

MRI T2/STIR epaxial muscle hyperintensity in some dogs with intervertebral disc extrusion corresponds to histologic patterns of muscle degeneration and inflammation.

Magnetic resonance imaging hyperintensity on T2-weighted turbo SE and STIR sequences of the paraspinal musculature in canine patients being imaged for thoracolumbar intervertebral disc extrusion is frequently observed but poorly understood in veterinary medicine. The objective of this prospective analytical study was to describe the histopathology of muscle hyperintensity in dogs with thoracolumbar intervertebral disc extrusions and to determine if a relationship exists between the presence of this hyperintensity and various patient factors. Twenty privately owned dogs who underwent surgical decompression of intervertebral disc extrusions diagnosed on MRI were enrolled (10 normal "control or nonaffected cases" without MRI paraspinal musculature hyperintensity and 10 "affected cases" with hyperintensity). Surgical biopsies of the epaxial musculature at the region of hyperintensity (affecteds) and at the site of the disc herniation (controls) were submitted for histopathology. The degree of myofiber degeneration and necrosis was scored using an ordinal scoring system: absent (0), minimal (10), mild (20), moderate (30), marked/severe (40), and massive (50). Associations between hyperintensity presence and patient age, weight, body condition, neurologic status, acuteness of onset, number of disc herniation sites, degree of spinal cord compression, and volume of herniated material were investigated. Nonaffected patients were significantly older (median age=9.4 years) than affected patients (median age=3.5 years), but no other significant associations were found. Acute myofiber degeneration/necrosis and intramuscular inflammation were observed in half of affected patients. Therefore, T2/STIR muscle hyperintensity in some patients with intervertebral disc extrusion may represent muscle degeneration and inflammation.

Sound Production and Mechanism in the Giant Sea Bass, Stereolepis gigas (Polyprionidae)

This study provided a first detailed description of the acoustic calls and the possible sound production mechanism in the Giant Sea Bass (Stereolepis gigas). Passive acoustic (hydrophone) recordings of Giant Sea Bass sounds were made of three mature individuals (40–45 kg) held in a circular 17,000 l seawater tank isolated from other fish species. Four basic sounds plus combinations were identified from the tank recordings when fish were present and were encountered on numerous occasions throughout the study. We classified the basic sounds as two types of pulses (A and B), short bursts, and long bursts, and combinations of short and long bursts. Mean peak frequencies of the four sound types were less than 39 Hz, while mean durations ranged from 67 ms to 545 ms, depending on sound type. We also obtained and dissected two mature, adult Giant Sea Bass to describe the morphology of a putative sound production mechanism. Five putative sonic muscles were discovered between each of the first six pleural ribs of the male examined. These five massive muscles (=obliquus superioris?) unite ribs 3 to 9 and were found at the level of the deep hypaxial musculature. The identification of these sounds and accompanying sonic mechanism marks the first occurrence of sound production in the family of wreckfishes (Polyprionidae). This knowledge of the acoustic characteristics increases our ability to document the presence, activity, and possibly the abundance of this critically endangered species at spawning sites.

Accelerometric Changes before and after Capacitive Resistive Electric Transfer Therapy in Horses with Thoracolumbar Pain Compared to a SHAM Procedure.

Simple SummaryCapacitive resistive electric transfer (CRET), a radiofrequency at 448 kHz, has been shown to result in increased muscle oxygenation and flexibility in the quadriceps muscle of human beings. In this study, 18 sport horses with thoracolumbar pain were divided into two homogenous groups: CRET (n = 9), subjected to four sessions of CRET during two consecutive weeks and SHAM (n = 9), subjected to the same sessions but with the device off. Clinical examination and accelerometry were made at the beginning and at the end of the study. A Mann-Whitney test and a Wilcoxon matched pair test were used to compare between SHAM and CRET groups and before and after the intervention, respectively. CRET horses showed a reduction of 1 degree in thoracolumbar pain (p = 0.002) and of 2 degrees in epaxial muscle pain (p = 0.03). SHAM horses had a reduction of 1 degree in thoracolumbar pain (p = 0.01). CRET horses presented increased dorsoventral power at walk and trot (p < 0.002), probably reflecting increased dorsoventral movement and flexibility. Such changes were not found in SHAM horses. No changes were found in the dorsoventral displacement of the center of gravity in either group. Our study demonstrated that sport horses with mild to moderate thoracolumbar pain could improve clinically and biomechanically after CRET therapy.Capacitive resistive electric transfer (CRET), a radiofrequency at 448 kHz, increases flexibility in quadricep muscles of human athletes. To assess whether CRET would result in clinical and biomechanical improvements in horses with thoracolumbar pain, 18 sport horses were divided into two groups: CRET (n = 9), subjected to four CRET sessions, during two consecutive weeks, and SHAM (n = 9), subjected to the same procedure with the device off. Clinical examination and accelerometry were performed before and after the four sessions. During the study, horses were in training and in active competition, and did not receive any other treatment. Mann-Whitney and a Wilcoxon matched pair tests were used to compare between the SHAM and CRET groups and before and after the intervention, respectively. CRET horses showed increased dorsoventral (p < 0.002), mediolateral and total power (p < 0.01) after the intervention, suggesting increased back flexibility. SHAM horses did not show any of these modifications after the intervention. No changes were found in the dorsoventral displacement of the gravity center in either group. Thoracolumbar pain decreased one degree after CRET (p = 0.002), and it did not change after SHAM. Epaxial muscle pain decreased two degrees after CRET (p = 0.03) and one degree after SHAM (p = 0.01). These results reflected that CRET therapy would increase back flexibility and decrease thoracolumbar and epaxial pain.

Multifactorial Causes of Chronic Mortality in Juvenile Sturgeon (Huso huso).

Simple SummarySturgeons are species of biological and economic importance. Among them, the beluga sturgeon (Huso huso, Linnaeus, 1758) is the largest freshwater fish and can reach a maximum weight of 1000 kg. Over 80% of existing sturgeon species are endangered, vulnerable, or on the brink of extinction because of their late sexual maturity and long periods between spawning in the wild. Many species of sturgeon are being reared to increase natural populations or produced for consumption as human food. Despite considerable global interest in sturgeon aquaculture, there is still a paucity of information on nutrient requirements and utilization and even their general nutrition. The development of sturgeon aquaculture has been accompanied by an increase in disease outbreaks, representing a serious problem. This paper presents an investigation of chronic mortality outbreak. The clinical presentation of diseased sturgeons, which is suggestive of a neurologic condition, was further investigated using various laboratory analyses that excluded the presence of the main viral agents of sturgeons while confirming the presence of both bacteria and mycetes. The pathological findings point out the severe myopathy, depletion of lymphohematopoietic tissue, and signs of degeneration consistent with a suboptimal environmental state. Results from chemical analyses also suggest nutritional imbalance.This investigation focused on an episode of chronic mortality observed in juvenile Huso huso sturgeons. The examined subjects underwent pathological, microbiological, molecular, and chemical investigations. Grossly severe body shape deformities, epaxial muscle softening, and multifocal ulcerative dermatitis were the main observed findings. The more constant histopathologic findings were moderate to severe rarefaction and disorganization of the lymphohematopoietic lymphoid tissues, myofiber degeneration, atrophy and interstitial edema of skeletal epaxial muscles, and degeneration and atrophy of the gangliar neurons close to the myofibers. Chemical investigations showed a lower selenium concentration in affected animals, suggesting nutritional myopathy. Other manifestations were nephrocalcinosis and splenic vessel wall hyalinosis. Septicemia due to bacteria such as Aeromonas veronii, Shewanella putrefaciens, Citrobacter freundii, Chryseobacterium sp., and pigmented hyphae were found. No major sturgeon viral pathogens were detected by classical methods. Next-generation sequencing (NGS) analysis confirmed the absence of viral pathogens, with the exception of herpesvirus, at the order level; also, the presence of Aeromonas veronii and Shewanella putrefaciens was confirmed at the family level by the metagenomic classification of NGS data. In the absence of a primary yet undetected biological cause, it is supposed that environmental stressors, including nutritional imbalances, may have led to immune system impairment, facilitating the entry of opportunistic bacteria and mycotic hyphae.

Variations in epaxial musculature dimensions and horse height over a period of eight hours

Variations in epaxial musculature dimensions and horse height over a period of eight hours

Fishes can use axial muscles as anchors or motors for powerful suction feeding.

ABSTRACTSome fishes rely on large regions of the dorsal (epaxial) and ventral (hypaxial) body muscles to power suction feeding. Epaxial and hypaxial muscles are known to act as motors, powering rapid mouth expansion by shortening to elevate the neurocranium and retract the pectoral girdle, respectively. However, some species, like catfishes, use little cranial elevation. Are these fishes instead using the epaxial muscles to forcefully anchor the head, and if so, are they limited to lower-power strikes? We used X-ray imaging to measure epaxial and hypaxial length dynamics (fluoromicrometry) and associated skeletal motions (XROMM) during 24 suction feeding strikes from three channel catfish (Ictalurus punctatus). We also estimated the power required for suction feeding from oral pressure and dynamic endocast volume measurements. Cranial elevation relative to the body was small (<5 deg) and the epaxial muscles did not shorten during peak expansion power. In contrast, the hypaxial muscles consistently shortened by 4–8% to rotate the pectoral girdle 6–11 deg relative to the body. Despite only the hypaxial muscles generating power, catfish strikes were similar in power to those of other species, such as largemouth bass (Micropterus salmoides), that use epaxial and hypaxial muscles to power mouth expansion. These results show that the epaxial muscles are not used as motors in catfish, but suggest they position and stabilize the cranium while the hypaxial muscles power mouth expansion ventrally. Thus, axial muscles can serve fundamentally different mechanical roles in generating and controlling cranial motion during suction feeding in fishes.

Pharmacokinetics of danofloxacin following intramuscular administration of a single dose in koi (Cyprinus carpio).

To determine the pharmacokinetics of danofloxacin following IM administration of a single dose (10 mg/kg) in koi (Cyprinus carpio). 69 healthy adult koi housed in a 980-L flow-through-system tank. 3 fish were kept as untreated controls, and the remaining 66 fish were assigned to 11 treatment groups with 6 fish/group. Fish in the treatment groups were given a single dose of danofloxacin (10 mg/kg) IM in the left epaxial musculature. Fifteen, 30, and 45 minutes and 1, 4, 12, 24, 72, 96, 120, and 144 hours after administration of danofloxacin, fish in each treatment group were euthanized, and blood samples and samples of liver, spleen, gill, anterior kidney, posterior kidney, skin and muscle, and scales were collected. Plasma and tissue drug concentrations were determined by liquid chromatography-tandem mass spectrometry, and noncompartmental pharmacokinetic analyses were performed. Tissues from the untreated control fish and fish euthanized 144 hours after danofloxacin administration were examined histologically. Maximum plasma concentration (mean, 8,315.7 ng/mL) was reached approximately 45 minutes after danofloxacin administration; plasma elimination half-life was 15 hours. Danofloxacin was detected in all examined tissues from all 6 fish euthanized 15 minutes after drug administration and was detected in some tissues from 3 of the 6 fish euthanized 144 hours after drug administration. For all tissues, results of histologic examination were unremarkable. IM administration of a single dose (10 mg/kg) of danofloxacin in koi resulted in rapid absorption, with maximum plasma concentration reached approximately 45 minutes after drug administration; the drug could still be detected in some tissues 144 hours after administration.

Novel concept for the epaxial/hypaxial boundary based on neuronal development.

Trunk muscles in vertebrates are classified as either dorsal epaxial or ventral hypaxial muscles. Epaxial and hypaxial muscles are defined as muscles innervated by the dorsal and ventral rami of spinal nerves, respectively. Each cluster of spinal motor neurons passing through dorsal rami innervates epaxial muscles, whereas clusters traveling on the ventral rami innervate hypaxial muscles. Herein, we show that some motor neurons exhibiting molecular profiles for epaxial muscles follow a path in the ventral rami. Dorsal deep-shoulder muscles and some body wall muscles are defined as hypaxial due to innervation via the ventral rami, but a part of these ventral rami has the molecular profile of motor neurons that innervate epaxial muscles. Thus, the epaxial and hypaxial boundary cannot be determined simply by the ramification pattern of spinal nerves. We propose that, although muscle innervation occurs via the ventral rami, dorsal deep-shoulder muscles and some body wall muscles represent an intermediate group that lies between epaxial and hypaxial muscles.

Effect of Caudal Traction on Mechanical Nociceptive Thresholds of Epaxial and Pelvic Musculature on a Group of Horses With Signs of Back Pain

Direct muscular attachment from lumbar vertebrae to the caudal vertebrae of the tail suggests that caudal traction, also described as a tail pull, may affect lumbar vertebral segments and/or associated soft tissues in horses. Traction is a commonly used human manual therapy technique used for pain relief and anecdotally observed to relieve pain in horses. However, research is lacking validating the efficacy of manual caudal traction on the horse. The objective of this study was to determine if caudal traction has an effect on mechanical nociceptive thresholds (MNTs) in a group of horses with clinical signs of back pain. Pressure algometry was used to measure MNTs of five bilateral anatomical sites in the epaxial and pelvic musculature of 11 horses referred to physiotherapy because of clinical signs of back pain. Measurements were recorded both before and immediately after traction. A significant difference (P ≤ .05) was identified between mean before and after caudal traction algometry measurements in all described sites. The percentage of MNT increase was highest in the thoracic region (83%) compared with the lumbar (50%) and the pelvic (52.4%) regions. These results support an effect of caudal traction in increasing MNTs in the thoracolumbar and pelvic regions in horses. Further research to determine the clinical effect of this technique is warranted.

Chondrocranial and hyobranchial structure in two South American suctorial tadpoles of the genus Telmatobufo (Anura: Calyptocephalellidae)

Chondrocranial and hyobranchial structure in two South American suctorial tadpoles of the genus Telmatobufo (Anura: Calyptocephalellidae). The chondrocranium, hyobranchium, rectus abdominis muscle, and epaxial musculature of Telmatobufo australis and T. ignotus are described. In addition, these structures were compared wih those of the non-suctorial Calyptocephalella gayi, the sister group of Telmatobufo.

Application of a Ridden Horse Pain Ethogram and Its Relationship with Gait in a Convenience Sample of 60 Riding Horses.

Simple SummaryHorse owners are poor at recognising lameness which may compromise equine welfare. A Ridden Horse Pain Ethogram, comprising 24 behaviours with specific definitions, was developed to facilitate identification of musculoskeletal pain. Previous studies demonstrated that the presence of ≥8/24 behaviours is likely to reflect musculoskeletal pain. The aim of this study was to further test the Ridden Horse Pain Ethogram by applying it to a convenience sample (n = 60) of sports horses and riding school horses in regular work and assumed by their owners to be working comfortably. All horses performed a purpose-designed dressage-type test of 8.5 min duration in walk, trot and canter, with their normal rider. The presence of increased back muscle tension or pain, poor saddle fit, gait abnormalities and rider skill were assessed by independent experts. The Ridden Horse Pain Ethogram was applied retrospectively, by a trained analyst, to video recordings which had been acquired in a standardised fashion. There was a significant association between the Ridden Horse Pain Ethogram score and lameness. Lame horses had higher scores than non-lame horses. Education of riders about behaviours which may reflect pain in ridden horses could allow the earlier identification of lame horses, whose welfare may be improved by accurate diagnosis and treatment.A Ridden Horse Pain Ethogram (RHpE) comprising 24 behaviours has been developed to facilitate the identification of musculoskeletal pain. The aim was to further test the RHpE by its application to a convenience sample (n = 60) of sports horses and riding school horses in regular work and assumed by their owners to be working comfortably. All horses performed a purpose-designed dressage-type test of 8.5 min duration in walk, trot and canter, with their normal rider. The RHpE was applied retrospectively to video recordings acquired in a standardised fashion. Seventy-three percent of horses were lame (≤ grade 2/8) on one or more limbs; 47% had gait abnormalities in canter. Ridden Horse Pain Ethogram scores ranged from 3 to 16/24 (median 9); rider skill score ranged from 2.5 to 8/10 (median 4.75). The effect of horse age, breed, sex, work-discipline, epaxial muscle hypertonicity or pain, an ill-fitting saddle, rider skill score, the presence of lameness or gait abnormalities in canter on the RHpE score was assessed using Poisson regression. Two variables were retained in the final multivariable analysis, rider skill score as a continuous variable (p < 0.001), and lameness (p = 0.008). A RHpE score ≥8 was a good indicator of the presence of musculoskeletal pain.

Crooked tail carriage in horses: Increased prevalence in lame horses and those with thoracolumbar epaxial muscle tension or sacroiliac joint region pain

SummaryThe relationship between lameness and crooked tail carriage (CTC) in horses is unclear. The objectives of this study were (i) to determine the association between CTC and lameness; (ii) among lame horses, to determine associations between CTC and lameness diagnosis, saddle slip, thoracolumbar range of motion (ROM), epaxial muscle tension and pain, and sacroiliac joint region (SIJR) pain, and (iii) to determine whether abolition of lameness and SIJR pain by diagnostic anaesthesia modified CTC. In this study, 520 lame and 170 nonlame sports horses were examined for CTC and other characteristics by one clinician (S.J.D.). All horses were evaluated when ridden. Lame horses were also assessed in hand and on the lunge. Crooked tail carriage, its direction, lameness, musculoskeletal and tack‐related parameters were recorded as binary variables and analysed using 2 × 2 contingency tables. Sacroiliac joint region pain was diagnosed using local anaesthesia. Standard errors are shown in square brackets. 32.5% of lame horses had CTC, compared with 5.3% of nonlame horses (odds ratio = 8.6 [confidence intervals 4.4, 16.7]; P = 2×10−12). Of 169 lame horses with CTC, 103 (60.9% [3.8%]) held their tail to the left. There was no association between the side of the predominant lame limb and CTC direction. However, CTC was more common (P = 0.005) in horses with hindlimb lameness (35.7% [2.4%], N = 401) compared with forelimb lameness (21.0% [4.1%], N = 100). Crooked tail carriage was associated with SIJR pain (P = 0.0007) and thoracolumbar epaxial muscle tension (P = 0.0007), but not with saddle slip, reduced thoracolumbar ROM or thoracolumbar epaxial muscle pain. Limitations of the study included the facts that nonlame horses were a convenience sample and lameness assessment, other clinical observations and determination of the presence of CTC were subjective, with potential for bias. Video recordings and photographs are available for verification of tail position. It was concluded that CTC is more prevalent in lame horses than nonlame horses. There is a positive association between CTC and hindlimb lameness, SIJR pain and thoracolumbar epaxial muscle tension.

The Tail of the Late Jurassic Sauropod Giraffatitan brancai: Digital Reconstruction of Its Epaxial and Hypaxial Musculature, and Implications for Tail Biomechanics

Dinosaur locomotion and biomechanics, especially of their pelvic girdles and hind limbs, have been analysed in numerous studies. However, detailed volumetric musculoskeletal models of their tails are rarely developed. Here, we present the first detailed three-dimensional volumetric reconstruction of the caudal epaxial and hypaxial musculature of the Late Jurassic sauropod Giraffatitan brancai, and highlight the importance and necessity of 3D modelling in musculoskeletal reconstructions. The tail of this basal macronarian is relatively short compared to diplodocids and other coexisting macronarians. The centre of mass lies well in front of the hind limbs, which support only ca. half the body weight. Still, our reconstruction suggests a total weight for the entire tail of ca. 2500 kg. We conclude that the hypaxial and hind limb muscles (more specifically the M. caudofemoralis longus and its counterpart the M. ilioischiocaudalis) in Giraffatitan were well developed and robustly built, compensating for the shorter length of the M. caufodemoralis longus, the main hind limb retractor muscle, in comparison with other sauropods. Our methodology allows a better-constrained reconstruction of muscle volumes and masses, in extinct taxa, and thus force and weight distributions, throughout the tail, than non-volumetric approaches.

Osteology of Klamelisaurus gobiensis (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods

Fossil-rich deposits from the Middle and Late Jurassic of China have yielded a diverse array of sauropod dinosaurs, including numerous species referred to Mamenchisaurus and Omeisaurus. Despite an abundance of fossils and a proliferation of taxa, the anatomy of Middle–Late Jurassic Chinese sauropods remains poorly documented. Here, we comprehensively redescribe and illustrate Klamelisaurus gobiensis from the Middle–Late Jurassic Shishugou Formation of northwest China. Phylogenetic analyses conducted under parsimony and time-calibrated Bayesian optimality criteria consistently recover Klamelisaurus as a member of a predominantly Chinese radiation of exceptionally long-necked eusauropods that includes Mamenchisaurus spp., Chuanjiesaurus, Qijianglong and Wamweracaudia. In most analyses, this lineage also includes Euhelopus, reviving a ‘traditional’ Euhelopodidae and calling into question the macronarian affinities of Euhelopus. Klamelisaurus shares several features with Euhelopus that are unique to a subset of East Asian taxa or rare among sauropods, including a convex ventral margin of the prezygodiapophyseal lamina in middle–posterior cervical vertebrae, a ventrally bifurcated postzygodiapophyseal lamina in posterior cervical vertebrae, and development of a rugose projection extending anteriorly from the epipophysis into the spinodiapophyseal fossa in most cervical vertebrae. Anatomical comparisons of the cervical vertebrae of Klamelisaurus to several other sauropodomorphs and insights from myological studies of extant archosaurs strongly suggest that this latter structure, often considered part of an epipophyseal-prezygapophyseal lamina, is an epaxial muscle scar that is distinct from pneumatic structures of the lateral surface of the neural spine. The phylogenetic and comparative anatomical data presented here provide a foundation for future revision of the taxonomy and systematics of sauropods from the Junggar and Sichuan basins.

Locomotor rib kinematics in two species of lizards and a new hypothesis for the evolution of aspiration breathing in amniotes

Most lizards walk and run with a sprawling gait in which the limbs are partly advanced by lateral undulation of the axial skeleton. Ribs and vertebrae are integral to this locomotor mode, but 3D motion of the axial skeleton has not been reported for lizard locomotion. Here, we use XROMM to quantify the relative motions of the vertebrae and ribs during slow treadmill locomotion in three savannah monitor lizards (Varanus exanthematicus) and three Argentine black and white tegus (Salvator merianae). To isolate locomotion, we selected strides with no concurrent lung ventilation. Rib rotations can be decomposed into bucket-handle rotation around a dorsoventral axis, pump-handle rotation around a mediolateral axis, and caliper rotations around a craniocaudal axis. During locomotion, every rib measured in both species rotated substantially around its costovertebral joint (8–17 degrees, summed across bucket, pump and caliper rotations). In all individuals from both species, the middle ribs rotated cranially through bucket and pump-handle motion during the propulsive phase of the ipsilateral forelimb. Axial kinematics during swing phase of the ipsilateral forelimb were mirror images of the propulsive phase. Although further work is needed to establish what causes these rib motions, active contraction of the hypaxial musculature may be at least partly responsible. Unilateral locomotor rib movements are remarkably similar to the bilateral pattern used for lung ventilation, suggesting a new hypothesis that rib motion during locomotion may have been an exaptation for the evolution of costal aspiration breathing in stem amniotes.

Pharmacokinetics of hydromorphone hydrochloride after intravenous and intramuscular administration in guinea pigs (Cavia porcellus).

To determine the pharmacokinetics of hydromorphone hydrochloride after IV and IM administration in guinea pigs (Cavia porcellus). 8 healthy adult guinea pigs (4 sexually intact females and 4 sexually intact males). In a crossover study, hydromorphone (0.3 mg/kg) was administered once IM (epaxial musculature) or IV (cephalic catheter) to each guinea pig at a 1-week interval (2 treatments/guinea pig). Blood samples were collected before and at predetermined intervals after drug administration via a vascular access port. Plasma hydromorphone concentrations were determined by liquid chromatography-tandem mass spectrometry. Noncompartmental analysis of data was used to calculate pharmacokinetic parameters. Mean ± SD clearance and volume of distribution for hydromorphone administered IV were 52.8 ± 13.5 mL/min/kg and 2.39 ± 0.479 L/kg, respectively. Mean residence time determined for the IV and IM administration routes was 0.77 ± 0.14 hours and 0.99 ± 0.34 hours, respectively. The maximum observed plasma concentration following IM administration of hydromorphone was 171.9 ± 29.4 ng/mL. No sedative effects were observed after drug administration by either route. Pharmacokinetic data indicated that hydromorphone at a dose of 0.3 mg/kg may be administered IV every 2 to 3 hours or IM every 4 to 5 hours to maintain a target plasma concentration between 2 and 4 ng/mL in guinea pigs. Hydromorphone had high bioavailability after IM administration. Further research is necessary to evaluate the effects of other doses and administration routes and the analgesic effects of hydromorphone in guinea pigs.

EVALUATION OF LOCALIZED INFLAMMATORY REACTIONS SECONDARY TO INTRAMUSCULAR INJECTIONS OF ENROFLOXACIN IN STRIPED BASS (MORONE SAXATILIS).

Enrofloxacin is a fluoroquinolone widely used in animals including fish. Intramuscular (IM) injection of enrofloxacin is a feasible and efficacious option for drug delivery. In many species IM injection has been associated with injection site reactions and increases in serum muscle enzymes. Injection site reactions have not been well characterized in fish. Three groups of striped bass (Morone saxatilis) received an IM injection of enrofloxacin 2.27% in the right epaxial musculature 24, 48, or 96 hr prior to evaluation. Mean dose was 7.69 mg/ kg (6.14-9.69 mg/kg). The 24- and 48-hr groups received an injection of equal-volume 0.9% saline in the left epaxial musculature. A corresponding noninjected tissue sample was designated in the left epaxial musculature from each fish of the 96-hr group. Fish were euthanized and injection sites and noninjection control sites were evaluated grossly and histologically. Grades 1-4 were assigned to samples, with grade 1 corresponding to normal tissue and grades 2, 3, and 4 corresponding to mild, moderate, and severe inflammation and/or necrosis respectively. Externally, all control and injection sites appeared visually unremarkable. On cut surface, epaxial muscle of the enrofloxacin-injected tissue appeared moderately to severely hemorrhagic compared to saline and noninjected tissue, which was normal or mildly hemorrhagic. Histologically, eight of eight noninjected tissues were grade 1. For saline-injected tissues, 14 of 16 tissues were grade 2 and 2 samples were grade 3 when 24- and 48-hr groups were combined. For enrofloxacin-injected tissues, 8 of the 8 24-hr samples were grade 3 and 16 of the 16 48- and 96-hr samples were grade 4. These data show that IM injection of enrofloxacin 2.27% is associated with severe hemorrhage, necrosis, and inflammation in striped bass, and may negatively affect animal welfare.

Usefulness of muscle condition score and ultrasonographic measurements for assessment of muscle mass in cats with cachexia and sarcopenia.

To compare muscle condition scores (MCSs) and muscle ultrasonographic measurements in cats with and without muscle loss and to evaluate repeatability and reproducibility of MCS assessment. 40 cats of various ages, body condition scores (BCSs), and MCSs. A prospective cross-sectional study was conducted. Body weight, BCS, MCS, epaxial muscle height (EMH), vertebral epaxial muscle score (VEMS), and forelimb epaxial muscle score (FLEMS) were assessed in each cat. The MCS for each cat was assessed 3 separate times by each of 5 raters. The MCS was significantly correlated with EMH (r = 0.59), VEMS (r = 0.66), and FLEMS (r = 0.41). For MCS, the overall value of the κ coefficient for interrater agreement (reproducibility) was 0.43 and the overall value of the κ coefficient for intrarater agreement (repeatability) ranged from 0.49 to 0.76. Ultrasonographic measurements of muscle may be useful for assessing muscle loss in individual cats over time. However, for the cats of this study, no advantage was observed for assessment of VEMS or FLEMS over EMH. Substantial repeatability and moderate reproducibility were shown when MCS was used for assessment of muscle mass in cats. Prospective ultrasonographic studies are warranted to evaluate the usefulness of MCS and EMH assessment for evaluation of changes in muscle mass of cats over time.

Effect of a functional feed additive on mitigation of experimentally induced gilthead sea bream Sparus aurata enteromyxosis.

In gilthead sea bream Sparus aurata, infection by Enteromyxum leei produces a cachectic syndrome with anorexia, weight loss, severe epaxial muscle atrophy and, eventually, death. Currently, there are neither vaccines nor effective prescription medicines to control this infection. Nutraceutical approaches are raising interest in the aquaculture industry, responding to the lack of therapeutic tools for the management of insidious chronic losses due to parasites. In this study, the effect of a commercially available health-promoting feed additive (SANACORE® GM) at 2 different doses was tested in comparison with a basal diet without the additive during a laboratory-controlled challenge with E. leei. Group performance and biometrical values were monitored, and an in-depth parasitological diagnosis, quantification of parasite loads and histopathological examination were carried out at the end of the trial. Supplemented diets mitigated the anorexia and growth arrestment observed in challenged fish fed the basal diet. This mitigation was maximum in the highest dose group, whose growth performance was not different from that of unchallenged controls. Treated groups also presented lower prevalence of infection and a lower parasite load, although the differences in the mean intensity of infection were not statistically significant. Although the decrease in parasite levels was similar with both doses of additive tested, the pathogeny of the infection was mostly suppressed with the higher dose, while only mitigated with the lower dose. The mechanisms involved in the effects obtained remain to be investigated, but the results point to a modulation of the immunopathological response to the infection.