Arterial Blood Gas, Electrolyte and Acid-Base Values as Diagnostic and Prognostic Indicators in Equine Colic.

The study aimed to investigate if arterial blood analysis in conscious horses presenting with signs of colic and breathing ambient air had diagnostic or prognostic value. Arterial blood samples from 352 horses presenting with colic at a university equine referral hospital were analysed for pH, partial pressure of carbon dioxide (PaCO2), partial pressure of oxygen (PaO2), concentrations of sodium (Na+), potassium (K+), ionised calcium (Ca2+) and chloride (Cl-), actual and standardised plasma bicarbonate concentration (HCO3- (P) and HCO3- (P, st)), blood and extracellular fluid base excess (Base (B) and Base (ecf)) and anion gap (AG). Results were compared to previously reported values for healthy horses, and comparisons were made between final diagnosis, treatment and survival to hospital discharge. Significant differences were found between colic cases and healthy reference values between some primary aetiologies. Overall, surgical and non-surgical colic cases differed in Ca2+ and Cl- concentrations and Ca2+ differed between cases that survived to discharge and those that did not. PaO2 differed between small intestinal surgical cases that survived and those that did not. From these results, we developed regression models that demonstrated excellent or good predictive value in identifying the likelihood of surgical versus medical management and survival to hospital discharge.

Neurovascular variations in the proximal plantar metatarsal region of the horse.

BACKGROUND: Neurovascular variation may be relevant when performing surgical techniques to the proximal plantar metatarsal region. OBJECTIVES: To document variations in the neurovascular anatomy of the proximal plantar metatarsal region and study the relationship of the neurovascular components to each other and other structures located in this area. STUDY DESIGN: Descriptive anatomical study. METHODS: Paired cadaver hind limbs from 15 horses were dissected from the distal tibia to the metatarsophalangeal joint. Deep branch of the lateral plantar nerve (DBLPN) length, location of its origin from the lateral plantar nerve (LPN), individual DBLPN ramifications into the suspensory ligament (SL) and relationship of the DBLPN to the plantar arch and accessory ligament of the deep digital flexor tendon (ALDDFT) were recorded. RESULTS: Mean DBLPN length was 5.8 ± 1.7 cm with the nerve arising 3.7 ± 1.5 cm proximal to the head of the fourth metatarsal bone (MTIV). There was a median of three individual DBLPN ramifications (range 2-6) entering the SL. There were no significant left/right differences. In 57% (CI 39%-74%; n = 17) limbs, the deep plantar arch was superficial to the DBLPN, whereas in 33% (CI 16%-50%; n = 10) limbs, the DBLPN passed between the venous and arterial components of the arch. In 10% (CI 1%-20%; n = 3) limbs, the deep plantar arch was deep to the DBLPN. In 67% (CI 50%-84%; n = 20) limbs, the DBLPN was superficial to the ALDDFT, whereas in 33% (CI 16%-50%; n = 10) limbs, the nerve ran deep to the ALDDFT. An additional branch from the LPN was noted in one limb. MAIN LIMITATIONS: Limbs were used from horses with unknown clinical history. CONCLUSIONS: Anatomical variation, in particular the relationship of the DBLPN and deep metatarsal fascia to the deep plantar arch and the ALDDFT is an important consideration when undertaking surgical approaches to the proximal plantar metatarsal region.

CT more accurately detects foreign bodies within the equine foot than MRI or digital radiography.

Identification and characterization of foreign bodies in the distal limb of horses poses a diagnostic challenge. The aims of this prospective experimental cadaver study were to describe the appearance of five foreign body materials within the equine hoof using CT, MRI, and digital radiography (DR) and to compare interrater agreement among three reviewers. Fifty foreign bodies consisting of five materials were implanted at a solar location or a coronary location in 25 equine cadaver feet. The images were reviewed by three equine veterinarians experienced in advanced imaging interpretation, who were blinded to the material of the foreign body. Foreign bodies were graded on visibility and appearance. Sensitivity and specificity were calculated for accurate identification of the different materials. Interrater agreement was assessed using Fleiss' kappa. Computed tomography had higher visibility score, sensitivity/specificity, and interrater agreement for detection of all materials; particularly slate, glass, and dry wood, compared to the other imaging modalities. Soaked wood and plastic had lower sensitivity (31-33%) on CT with a similar attenuation of the two materials. Foreign bodies were often visible on MRI, although with similar appearance and unclear details. On DR, only slate and glass were visible. The interrater agreement for identifying the correct material was almost perfect for slate, glass, and dry wood (κ = 0.92-1.00) and poor for plastic and soaked wood (κ < 0.20) on CT. Interrater agreement was poor for all materials on MRI and DR (κ < 0.20), with the except for fair (κ = 0.28) for slate on DR and moderate (κ = 0.28) for soaked wood on MRI.

Epidural administration of opioid analgesics improves quality of recovery in horses anaesthetised for treatment of hindlimb synovial sepsis.

BACKGROUND: Opioid epidural analgesia has been shown to provide effective analgesia in horses. There is a lack of evidence regarding the effect of opioid epidural analgesia on quality of recovery in horses. OBJECTIVES: Identify whether opioid epidural analgesia influences quality of recovery in horses undergoing general anaesthesia required for management of hindlimb synovial sepsis. STUDY DESIGN: Single-centre retrospective cross-sectional study. METHODS: Data were obtained from the clinical records of horses which had undergone arthroscopic or tenoscopic surgery for management of hindlimb synovial sepsis over a 9-year period in a referral hospital population. Multivariable logistic regression analysis was used to identify the perioperative factors that impact on quality of recovery. RESULTS: Records from 149 horses, undergoing 170 general anaesthetics were included. Multivariable logistic regression analysis showed that opioid epidural analgesia (OR 3.0, 95% CI 1.2 to 7.2, P = .02) was associated with good quality of recovery, whereas Cob breeds (OR 0.16, 95% CI 0.06 to 0.46, P = .001), age (in years) (OR 0.90, 95% CI 0.83 to 0.97, P = .004) increasing intraoperative dosages (in mg/kg) of thiopental (OR 0.64, 95% CI 0.46 to 0.90, P = .01) or ketamine (OR 0.42, 95% CI 0.18 to 0.98, P = .04) were associated with poor quality of recovery. MAIN LIMITATIONS: Certain variables that may influence quality of recovery, such as patient temperament and hindlimb orthopaedic co-morbidities were not recorded. The clinical prediction model obtained is only applicable to the specific facilities, population and perianaesthetic management practiced at our institution. CONCLUSIONS: Opioid epidural analgesia is significantly associated with good quality of recovery in horses undergoing general anaesthesia required for management of hindlimb synovial sepsis. Other risk factors, such as increasing age, cob breed, use of higher intraoperative dosages (in mg/kg) of ketamine and/or thiopental, were associated with poor quality of recovery.

Mouse microRNA signatures in joint ageing and post-traumatic osteoarthritis.

OBJECTIVE: This study investigated mice serum and joint microRNA expression profiles in ageing and osteoarthritis to elucidate the role of microRNAs in the development and progression of disease, and provide biomarkers for ageing and osteoarthritis. DESIGN: Whole joints and serum samples were collected from C57BL6/J male mice and subjected to small RNA sequencing. Groups used included; surgically-induced post-traumatic osteoarthritis, (DMM; 24 months-old); sham surgery (24 months-old); old mice (18 months-old); and young mice (8 months-old). Differentially expressed microRNAs between the four groups were identified and validated using real-time quantitative PCR. MicroRNA differential expression data was used for target prediction and pathway analysis. RESULTS: In joint tissues, miR-140-5p, miR-205-5p, miR-682, miR-208b-3p, miR-499-5p, miR-455-3p and miR-6238 were differentially expressed between young and old groups; miR-146a-5p, miR-3474, miR-615-3p and miR-151-5p were differentially expressed between DMM and Sham groups; and miR-652-3p, miR-23b-3p, miR-708-5p, miR-5099, miR-23a-3p, miR-214-3p, miR-6238 and miR-148-3p between the old and DMM groups. The number of differentially expressed microRNAs in serum was higher, some in common with joint tissues including miR-140-5p and miR-455-3p between young and old groups; and miR-23b-3p, miR-5099 and miR-6238 between old and DMM groups.We confirmed miR-140-5p, miR-499-5p and miR-455-3p expression to be decreased in old mouse joints compared to young, suggesting their potential use as biomarkers of joint ageing in mice. CONCLUSIONS: MiR-140-5p, miR-499-5p and miR-455-3p could be used as joint ageing biomarkers in mice. Further research into these specific molecules in human tissues is now warranted to check their potential suitability as human biomarkers of ageing.

Post-traumatic osteoarthritis development is not modified by postnatal chondrocyte deletion of Ccn2.

CCN2 is a matricellular protein involved in several crucial biological processes. In particular, CCN2 is involved in cartilage development and in osteoarthritis. Ccn2 null mice exhibit a range of skeletal dysmorphisms, highlighting its importance in regulating matrix formation during development; however, its role in adult cartilage remains unclear. The aim of this study was to determine the role of CCN2 in postnatal chondrocytes in models of post-traumatic osteoarthritis (PTOA). Ccn2 deletion was induced in articular chondrocytes of male transgenic mice at 8 weeks of age. PTOA was induced in knees either surgically or non-invasively by repetitive mechanical loading at 10 weeks of age. Knee joints were harvested, scanned with micro-computed tomography and processed for histology. Sections were stained with Toluidine Blue and scored using the Osteoarthritis Research Society International (OARSI) grading system. In the non-invasive model, cartilage lesions were present in the lateral femur, but no significant differences were observed between wild-type (WT) and Ccn2 knockout (KO) mice 6 weeks post-loading. In the surgical model, severe cartilage degeneration was observed in the medial compartments, but no significant differences were observed between WT and Ccn2 KO mice at 2, 4 and 8 weeks post-surgery. We conclude that Ccn2 deletion in chondrocytes does not modify the development of PTOA in mice, suggesting that chondrocyte expression of CCN2 in adults is not a crucial factor in protecting cartilage from the degeneration associated with PTOA.This article has an associated First Person interview with the first author of the paper.

Serum snoRNAs as biomarkers for joint ageing and post traumatic osteoarthritis.

The development of effective treatments for the age-related disease osteoarthritis and the ability to predict disease progression has been hampered by the lack of biomarkers able to demonstrate the course of the disease. Profiling the expression patterns of small nucleolar RNAs (snoRNAs) in joint ageing and OA may provide diagnostic biomarkers and therapeutic targets. This study determined expression patterns of snoRNAs in joint ageing and OA and examined them as potential biomarkers. Using SnoRNASeq and real-time quantitative PCR (qRT-PCR) we demonstrate snoRNA expression levels in murine ageing and OA joints and serum for the first time. SnoRNASeq identified differential expression (DE) of 6 snoRNAs in young versus old joints and 5 snoRNAs in old sham versus old experimental osteoarthritic joints. In serum we found differential presence of 27 snoRNAs in young versus old serum and 18 snoRNAs in old sham versus old experimental osteoarthritic serum. Confirmatory qRT-PCR analysis demonstrated good correlation with SnoRNASeq findings. Profiling the expression patterns of snoRNAs is the initial step in determining their functional significance in ageing and osteoarthritis, and provides potential diagnostic biomarkers and therapeutic targets. Our results establish snoRNAs as novel markers of musculoskeletal ageing and osteoarthritis.

Resveratrol and N-acetylcysteine influence redox balance in equine articular chondrocytes under acidic and very low oxygen conditions.

Mature articular cartilage is an avascular tissue characterized by a low oxygen environment. In joint disease, acidosis and further reductions in oxygen levels occur, compromising cartilage integrity.This study investigated how acidosis and very low oxygen levels affect components of the cellular redox system in equine articular chondrocytesand whether the antioxidants resveratrol and N-acetylcysteine could modulate this system. We used articular chondrocytes isolated from nondiseased equine joints and cultured them in a 3-D alginate bead system for 48h in <1, 2, 5, and 21% O2 at pH 7.2 or 6.2 in the absence or presence of the proinflammatory cytokine, interleukin-1ß (10ng/ml).In addition, chondrocytes were cultured with resveratrol (10µM) or N-acetylcysteine (NAC) (2mM).Cell viability, glycosaminoglycan (GAG) release, mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS), GSH:GSSG ratio, and SOD1 and SOD2 protein expression were measured. Very low levels of oxygen (<1%), acidosis (pH 6.2), and exposure to IL-1ß led to reductions in cell viability, increased GAG release, alterations in ΔΨm and ROS levels, and reduced GSH:GSSG ratio. In addition, SOD1 and SOD2 protein expressions were reduced. Both resveratrol and NAC partially restored ΔΨm and ROS levels and prevented GAG release and cell loss and normalized SOD1 and SOD2 protein expression. In particular NAC was highly effective at restoring the GSH:GSSG ratio.These results show that the antioxidants resveratrol and N-acetylcysteine can counteract the redox imbalance in articular chondrocytes induced by low oxygen and acidic conditions.

Use of immunohistochemical staining and electron microscopy to aid in diagnosis of soft tissue sarcomas associated with the fetlock joint in two horses.

Soft tissue sarcomas of the equine distal limb associated with joints, sheaths, or bursae have rarely been reported. Accurate diagnosis of these tumors is challenging in both human beings and veterinary species. Immunohistochemical staining and transmission electron microscopy have been used in human beings to reduce misdiagnosis. The current report describes 2 mature horses presenting with lameness and swelling associated with the dorsal aspect of the metacarpo(tarso)phalangeal joint. In both cases, surgical excision was performed with subsequent histological analysis of the masses to determine the tissue of origin. In both cases, immunohistochemical staining and transmission electron microscopy aided the definitive diagnosis of fibrosarcoma associated with the fetlock joints of 2 horses.

Expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in equine laminitis.

Tissue sensitisation and chronic pain have been described in chronic-active laminitis in the horse, making treatment of such cases difficult. Purinergic P2X receptors are linked to chronic pain and inflammation. The aim of this study was to examine the expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in the hoof, palmar digital vessels and nerve, dorsal root ganglia and spinal cord in horses with chronic-active laminitis (n=5) compared to non-laminitic horses (n=5). Immunohistochemical analysis was performed on tissue sections using antibodies against P2X receptor subtypes 1-3 and 7. In horses with laminitis, there was a reduction in the thickness of the tunica media layer of the palmar digital vein as a proportion of the whole vessel diameter (0.48±0.05) compared to the non-laminitic group (0.57±0.04; P=0.02). P2X receptor subtype 3 was expressed in the smooth muscle layer (tunica media) of the palmar digital artery of horses with laminitis, but was absent in horses without laminitis. There was strong expression of P2X receptor subtype 7 in the proliferating, partially keratinised, epidermal cells of the secondary epidermal lamellae in the hooves of horses with laminitis, but no immunopositivity in horses without laminitis.

Growth factor regulation of intracellular pH homeostasis under hypoxic conditions in isolated equine articular chondrocytes.

Hypoxia and acidosis are recognized features of inflammatory arthroses. This study describes the effects of IGF-1 and TGF-ß(1) on pH regulatory mechanisms in articular cartilage under hypoxic conditions. Acid efflux, reactive oxygen species (ROS), and mitochondrial membrane potential were measured in equine articular chondrocytes isolated in the presence of serum (10% fetal calf serum), IGF-1 (1, 10, 50, 100 ng/ml) or TGF-ß(1) (0.1, 1, 10 ng/ml) and then exposed to a short-term (3 h) hypoxic insult (1% O(2)). Serum and 100 ng/ml IGF-1 but not TGF-ß(1) attenuated hypoxic regulation of pH homeostasis. IGF-1 appeared to act through mitochondrial membrane potential stabilization and maintenance of intracellular ROS levels in very low levels of oxygen. Using protein phosphorylation inhibitors PD98059 (25 µM) and wortmannin (200 nM) and Western blotting, ERK1/2 and PI-3 kinase pathways are important for the effect of IGF-1 downstream to ROS generation in normoxia but only PI-3 kinase is implicated in hypoxia. These results show that oxygen and growth factors interact to regulate pH recovery in articular chondrocytes by modulating intracellular oxygen metabolites.

Magnetic resonance imaging findings of equine solar penetration wounds.

The magnetic resonance (MR) imaging features, signalment, clinical history and outcome of 55 horses with a penetrating sole injury were evaluated. Our aim was to describe MR imaging findings within the hoof capsule, assess the utility of the technique and give recommendations for the optimal MR imaging protocol to evaluate such injuries. Data from five equine hospitals were analyzed retrospectively. The tract was more likely to be visualized in animals scanned within the first week postinjury. There was no significant predisposition based on breed, age, or gender. T2*W transverse sequences were the most useful for assessment of solar penetrations due to their orientation perpendicular to the deep digital flexor tendon, the reduced scanning time, and the T2* capability of enhancing magnetic susceptibility caused by hemorrhage.

Stem cell-based therapies for bone repair.

This article provides an overview of the cellular and molecular events involved in bone repair and the current approaches to using stem cells as an adjunct to this process. The article emphasizes the key role of osteoprogenitor cells in the formation of bone and where the clinical applications of current research may lend themselves to large animal orthopaedics. The processes involved in osteogenic differentiation are presented and strategies for bone formation, including induction by osteogenic factors, bioscaffolds, and gene therapy, are reviewed.

Rapid effects of hypoxia on H+ homeostasis in articular chondrocytes.

Articular chondrocytes experience low oxygen (O(2)) levels compared with many other tissues, and values fall further in disease states. Chondrocyte intracellular pH (pH(i)) is a powerful modulator of matrix synthesis and is principally regulated by Na(+)-H(+) exchange (NHE). In equine chondrocytes, NHE is inhibited when cells are incubated for 3 h at low O(2), leading to intracellular acidosis. O(2)-dependent changes in reactive oxygen species (ROS) levels appear to underlie this effect. The present study examines whether hypoxia can influence chondrocyte NHE activity and pH(i) over shorter timescales using the pH-sensitive fluoroprobe BCECF in cells isolated not only from equine cartilage but also from bovine tissue. O(2) levels in initially oxygenated solutions gassed with N(2) fell to approximately 1% within 2 h. A progressive fall in pH(i) and acid extrusion capacity was observed, with statistically significant effects (P < 0.05) apparent within 3 h. For equine and bovine cell populations subjected to step change in O(2) by resuspension in hypoxic (1%) solutions, a decline in acid extrusion and pH(i) was observed within 10 min and continued throughout the recording period. This effect represented inhibition of the NHE-mediated fraction of acid extrusion. Cells subjected to hypoxic solutions supplemented with CoCl(2) (100 microM) or antimycin A (100 microM) to raise levels of ROS did not acidify. The conserved nature and rapidity of the response to hypoxia has considerable implications for chondrocyte homeostasis and potentially for the maintenance of cartilage integrity.