Medical honey for canine nasal intertrigo: A randomized, blinded, placebo-controlled, adaptive clinical trial to support antimicrobial stewardship in veterinary dermatology.

Intertrigo is a skin fold dermatitis often requiring recurrent treatment with topical antiseptics or antibiotics, which can select antimicrobial resistance. To minimize this risk, we tested the effectiveness of medical-grade Manuka honey at treating intertrigo as compared to a placebo hydrogel. We additionally characterized the culturable microbial flora of intertrigo and recorded any adverse effect with either treatment. During this randomized, placebo-controlled, double-blinded, adaptive group-sequential trial, the owners washed the affected sites on their dog with water, dried and applied a thin film of either the honey or the placebo product once daily for 21 days. Cytological and lesional composite scores, owner-assessed pruritus, and microbial cultures were assessed prior to treatment and on Day-22. The fixed effects of time, treatment, and animal-related variables on the pruritus and on each composite score, accounting for random dog effect, were estimated separately with generalized linear mixed models for repeated count outcomes (α = 0.05). The null hypothesis of equal treatment effects was rejected at the first interim analysis. The placebo (n = 16 dogs) outperformed the medical honey (n = 13 dogs) at improving both the cytological score (Treatment×Time = -0.35±0.17; P = 0.04) and clinical score (Treatment×Time = -0.28±0.13; P = 0.04). A microbial burden score higher than 4 increased the severity of the cytological score (dichotomous score: 0.29±0.11; P = 0.01), which in turn increased the severity of the clinical score and pruritus score. For every unit increase in cytological score, the linear predictor of clinical score increased by 0.042±0.019 (P = 0.03), and the one of pruritus score increased by 0.12±0.05 (P = 0.01). However, medical honey outperformed the placebo at alleviating the dog's owner-assessed pruritus after statistically controlling for masking effects (Time = -0.94±0.24; P = 0.002; and Treatment×Time = 0.80±0.36; P = 0.04). Unilateral tests of the least-square mean estimates revealed that honey only significantly improved the pruritus (Hommel-adjusted P = 0.003), while the placebo only improved the cytological and clinical scores (Hommel-adjusted P = 0.01 and 0.002, respectively). Taken together, these results question the value of Manuka honey at treating nasal intertrigo in dogs.

In vitro effects of dalteparin on thrombin generation in canine plasma.

BACKGROUND: The calibrated automated thrombogram (CAT) is a functional thrombin generation (TG) assay that may provide a new approach for monitoring anticoagulant therapy in dogs. The effects of dalteparin on TG variables in dogs are unknown. OBJECTIVES: Objectives were to establish normal TG variable ranges in dogs and measure the in vitro TG variables in canine pooled platelet-poor plasma (PPP) spiked with different dalteparin concentrations. METHODS: In the first experiment, plasma samples from 25 adult healthy Beagle dogs and 11 client-owned healthy dogs of multiple breeds was measured individually for obtaining normal TG values. In the second experiment, separate pools of the remaining PPP from 24 of the 25 previous adult Beagles and from 45 different client-owned dogs were spiked with dalteparin at 9 concentrations with increasing anti-factor Xa (anti-FXa) activity. Activated partial thromboplastin time, tissue factor-induced TG, and anti-FXa activity were measured for each concentration. Concentration-response relationships were determined with ADAPT v.5, using various nonlinear regression models for stimulatory or inhibitory effects. RESULTS: Thrombin generation ranges of client-owned dogs and Beagles were equivalent only for time-to-peak (P < .05). In vitro dalteparin resulted in a concentration-dependent decrease in endogenous thrombin potential (ETP) in pooled PPP. The estimated dalteparin concentration that produced half the maximal inhibition of baseline ETP (IC50 ) was 0.289 U/mL. Thrombin generation and anti-FXa activity were more sensitive than APTT to detect the effects of dalteparin. CONCLUSIONS: The CAT assay can measure the effects of dalteparin in canine plasma, resulting in significant dose-dependent decreases in ETP, prompting further in vivo investigation.

Inhaled nitric oxide prevents NSAID-induced renal impairment in pseudo-normovolaemic piglets.

OBJECTIVE: Inhaled nitric oxide (iNO) is commonly used as a treatment of pulmonary hypertension. Its action is purported to be specific to the lung, but extrapulmonary effects have been reported. The objective of this study was to evaluate if iNO could compensate the renal impairment induced by ketoprofen, a conventional non-steroidal anti-inflammatory drug (NSAID), during general anaesthesia. METHODS: Under pseudo-normovolaemic condition, thirty piglets were randomly assigned into 5 equal groups and equipped for renal and systemic parameters measurements. A first experiment was carried out to validate methods and reproduce the renal effects of iNO (40 ppm) in comparison with a placebo (100% oxygen). In a second experiment, iNO was inhaled for 120 minutes right after NSAID treatment (ketoprofen 2 mg×kg-1 IV, and 40 ppm iNO; group KiNO) and its effects were compared to ketoprofen alone (2 mg×kg-1 IV; group K) and placebo (saline; group C). RESULTS: In this model, iNO increased significantly renal blood flow measured by ultrasonic (RBFUL: +53.2±17.2%; p = 0.008) and by PAH clearance (RBFPAH:+78.6±37.6%; p = 0.004) methods, glomerular filtration rate (GFR: +72.6±32.5%; p = 0.006) and urinary output (UO: +47.4±24.2%; p = 0.01). In the second experiment, no significant temporal variation was noted for renal parameters in groups KiNO and C, whereas a significant and constant decrease was observed in the group K for RBFUL (max -19.0±7.1%), GFR (max -26.6±10.4%) and UO (max -30.3±10.5%). CLINICAL SIGNIFICANCE: Our experiments show that iNO, released from its transport forms after its inhalation, can improve renal safety of NSAIDs. This result is promising regarding the use of NSAIDs in critical conditions, but needs to receive clinical confirmation.

Comparison of lidocaine and lidocaine-epinephrine for the paravertebral brachial plexus block in dogs.

OBJECTIVE: To compare the motor and sensory block efficacy and duration of a modified paravertebral brachial plexus block (PBPB) after administration of lidocaine alone (LI) or combined with epinephrine (LE). STUDY DESIGN: Prospective, randomized, blinded, crossover study. ANIMALS: A total of eight healthy female Beagle dogs. METHODS: Under general anesthesia, modified PBPB was performed on the left thoracic limb using neurostimulation and/or ultrasound guidance to administer lidocaine (2 mg kg-1; 0.2 mL kg-1) either alone (treatment LI, n = 10) or with epinephrine (1:100,000; treatment LE, n = 9). Sensory block was evaluated through reaction to a painful mechanical stimulus applied at five sites on the limb. Motor block effect was evaluated according to visual gait assessments and thoracic limb vertical force measurements under dynamic and static conditions. Data were analyzed using repeated-measures generalized estimating equations. All statistical tests were performed two-sided at the α = 0.05 significance threshold. RESULTS: The duration of sensory block did not differ significantly between treatments. Visible gait impairment was more persistent in LE than in LI (118 ± 63 minutes for LI and 163 ± 23 minutes for LE; mean ± standard deviation) (p = 0.027). At nadir value, dynamic peak vertical force was lower in LE than in LI (p = 0.007). For both dynamic and static evaluations, the nadir and the return to baseline force were delayed in LE (return to normal at 180-200 minutes) when compared with LI (130-140 minutes) (p < 0.005). CONCLUSIONS AND CLINICAL RELEVANCE: The addition of epinephrine to lidocaine prolonged the duration and increased the intensity of the regional block, as verified by visual gait assessment and kinetic analysis. No significant difference was noted between treatments regarding sensory blockade. Kinetic analysis could be useful to evaluate regional anesthetic effect in dogs.

Plasma concentration and cardiovascular effects of intramuscular medetomidine combined with three doses of the peripheral alpha2-antagonist MK-467 in dogs.

OBJECTIVE: We investigated the plasma concentrations and cardiovascular effects of intramuscularly (IM) administered medetomidine, administered alone or with three different doses of MK-467. STUDY DESIGN: Prospective, randomized, open, crossover trial. ANIMALS: Eight purpose-bred healthy Beagle dogs. METHODS: Each dog was administered four treatments: medetomidine 20 µg kg-1 IM alone or mixed in the same syringe with MK-467 (200 µg kg-1, 400 µg kg-1 or 600 µg kg-1). Instrumentation was performed under standardized anaesthesia. The dogs were allowed to recover before measurement of baseline values. Composite sedation scores, cardiovascular variables, i.e., heart rate (HR), cardiac output (CO), mean arterial and central venous blood pressures (MAP and CVP) and arterial blood gases were recorded at baseline and for 60 minutes after treatment. Drug concentrations in venous plasma were analysed. Generalized linear mixed models for repeated measures with post hoc Bonferroni correction were used with statistical significance level set at α=0.05. RESULTS: All treatments initially demonstrated the effects of medetomidine: HR and CO decreased and CVP increased. MAP transiently increased and then significantly decreased from baseline with the two highest MK-467 doses. The cardiovascular effects of medetomidine disappeared more rapidly with MK-467 than with medetomidine alone. With medetomidine alone, sedation scores remained high until the end of the 60 minute follow-up. Maximum concentrations of medetomidine were more rapidly achieved and were higher with MK-467. CONCLUSIONS AND CLINICAL RELEVANCE: Initial haemodynamic effects of medetomidine were not prevented by MK-467, but these effects were attenuated and their duration shortened by MK-467, independently of dose. Absorption of medetomidine was accelerated by MK-467, when administered concomitantly IM, resulting in faster sedation; addition of MK-467 shortened the sedative effect of medetomidine.

Analgesic efficacy of tramadol in cats with naturally occurring osteoarthritis.

OBJECTIVES: This study aimed to (1) compare outcome assessments in normal and osteoarthritic cats and (2) evaluate the analgesic efficacy of tramadol in feline osteoarthritis (OA), in a prospective, randomised, blinded, placebo-controlled, crossover design. METHODS: Twenty cats were included after clinical examination, blood work and full body radiographs were performed. In Phase 1, outcome assessments aimed to differentiate normal (n = 5; i.e. exempt of any radiographic and clinical sign of OA) from OA (n = 15) cats. In Phase 2, OA cats were treated twice daily with a placebo (PG: cornstarch 15 mg) or tramadol (TG: 3 mg/kg) orally for 19 days, with a 3-month washout period between treatments. Evaluations were performed in normal and OA cats at baseline and consisted of: 1) peak vertical force (PVF) after staircase exercise; 2) telemetered night-time motor activity (NMA); and 3) response to mechanical temporal summation (RMTS). After treatment, PVF, NMA and RMTS evaluations were repeated in OA cats. Data were analysed with mixed model methods with an alpha-threshold of 5%. RESULTS: Phase 1: 1) PVF (% of body weight; mean ± SD) was higher in normal (59 ± 10.5) than in OA cats (50.6 ± 5.7) (p = 0.005); 2) NMA (no unit) was not different between groups; 3) RMTS (number of stimuli; median (range)) was higher in normal [29.5 (23.5-30)] than in OA cats [14 (8.5-28)] (p < 0.0001). Phase 2: PVF, NMA and RMTS presented a treatment effect (p = 0.024, p = 0.008 and p = 0.018, respectively). No clinically important adverse-effects were observed. CONCLUSION: Outcome assessments such as kinetics (PVF) and evaluation of central sensitisation (RMTS) are discriminant of OA status. Mobility measured by NMA was not discriminant of OA status, however it increased in OA cats with tramadol treatment. Nociceptive hypersensitivity quantified by RMTS was evident in OA cats and was responsive to tramadol treatment.

Pharmacokinetics of Lidocaine Hydrochloride Administered with or without Adrenaline for the Paravertebral Brachial Plexus Block in Dogs.

Adrenaline is known to prolong the duration of local anesthesia but its effects on the pharmacokinetic processes of local anesthetic drugs are not fully understood. Our objective was to develop a compartmental model for quantification of adrenaline's impact on the pharmacokinetics of perineurally-injected lidocaine in the dog. Dogs were subjected to paravertebral brachial plexus block using lidocaine alone or adrenalinated lidocaine. Data was collected through a prospective, randomised, blinded crossover protocol performed over three periods. Blood samples were collected during 180 minutes following block execution. Compartmental pharmacokinetic models were developed and their goodness-of-fit were compared. The lowering effects of adrenaline on the absorption of lidocaine were statistically determined with one-sided tests. A one-compartment disposition model with two successive zero-order absorption processes best fitted our experimental data. Adrenaline decreased the peak plasma lidocaine concentration by approximately 60% (P < 0.001), decreased this local anesthetic's fast and slow zero-order absorption rates respectively by 50% and 90% (P = 0.046, and P < 0.001), which respective durations were prolonged by 90% and 1300% (P < 0.020 and P < 0.001). Lidocaine demonstrated a previously unreported atypical absorption profile following its paravertebral injection in dogs. Adrenaline decreased the absorption rate of lidocaine and prolonged the duration of its absorption.

Haemodynamic interactions of medetomidine and the peripheral alpha-2 antagonist MK-467 during step infusions in isoflurane-anaesthetised dogs.

The haemodynamic interactions of a step infusion with medetomidine (MED) and the peripherally acting alpha-2 antagonist MK-467 (MK) were compared with MED infused alone in isoflurane-anaesthetised dogs. Eight purposely-bred Beagles were used in a randomised crossover study. Anaesthesia was induced with propofol intravenously (IV) and maintained with isoflurane in oxygen. Dogs received 1.25 µg/kg MED as a 1 min loading dose IV, along with a step-down MED infusion at rates of 8.0 µg/kg/h (step 1: 0-20 min), 5.5 µg/kg/h (step 2: 20-40 min) and 4.0 µg/kg/h (step 3: 40-95 min). Five minutes after starting the MED infusion, the dogs received MK-467 in a step-up infusion at rates of 100 µg/kg/h (step 1: 5-35 min), 200 µg/kg/h (step 2: 35-65 min) and 500 µg/kg/h (step 3: 65-95 min). Heart rate (HR), systolic (SAP) and mean arterial (MAP) blood pressures and arteriovenous oxygen content differences (a-vO2 diff) were calculated. Plasma drug concentrations were analysed. Repeated-measures general linear mixed models with Bonferroni correction were used for statistical analyses. MED infusion alone increased SAP maximally by 24.9%, MAP by 34.7% and a-vO2 diff by 222.5%, and reduced HR by 32.3%, but these changes were significantly attenuated by MK-467. Most MED effects returned to baseline during step 2 of MK-467 infusion and step 3 of MED infusion (MED/MK-467 ratio 1:18 to 1:50). Plasma concentrations of MED tended to be lower with the addition of MK-467. The use of step infusions helped to narrow down the therapeutic range for the MED/MK-467 infusion dose ratio during isoflurane anaesthesia in dogs.

Association between sensitisation and pain-related behaviours in an experimental canine model of osteoarthritis.

Evaluation of nociceptive sensitisation in canine osteoarthritis studies has been poorly reported, or even related to other clinical symptoms. In 16 dogs, peak vertical force (PVF), subjective pain assessment using 3 scales, sympathetic stress response with electrodermal activity (EDA) measurement, and behavioural changes with video analysis and telemetered motor activity were quantified at baseline (D-7), and 28 and 56 days post transection of the cranial cruciate ligament. As markers of central sensitisation, selected spinal cord biomarkers (substance P and transthyretin) were quantified at D56. Electrical withdrawal thresholds on the stifle and the tail were measured as indicative of peripheral and central quantitative sensory testing (QST) sensitisation, respectively. The effects of vehicle administration (n=8) were compared with tiludronate (2mg/kg subcutaneously, q2 week, starting at D0) administration. Generalized estimated equations tested the association between the behavioural and physiological methods and QST sensitisation, and therefore the sensitivity of the methods for detecting treatment efficacy. Compared to tiludronate, at D56, vehicle-treated dogs had increased spinal substance P (P=0.01), concomitant decreased transthyretin (P=0.02), and (compared to baseline) demonstrated peripheral and central QST sensitisation, which was not present for tiludronate. Only PVF, the spontaneous behaviour "walking with full weight-bearing," and EDA were associated with occurrence of QST sensitisation and indicated significant tiludronate analgesic efficacy after inclusion of central QST sensitisation as a predictor variable in the statistical model. This study establishes the strong interest to implement QST as a predictor of canine osteoarthritis pain symptoms explained by pain sensitisation.

A posteriori comparison of natural and surgical destabilization models of canine osteoarthritis.

For many years Canis familiaris, the domestic dog, has drawn particular interest as a model of osteoarthritis (OA). Here, we optimized the dog model of experimental OA induced by cranial cruciate ligament sectioning. The usefulness of noninvasive complementary outcome measures, such as gait analysis for the limb function and magnetic resonance imaging for structural changes, was demonstrated in this model. Relationships were established between the functional impairment and the severity of structural changes including the measurement of cartilage thinning. In the dog model of naturally occurring OA, excellent test-retest reliability was denoted for the measurement of the limb function. A criterion to identify clinically meaningful responders to therapy was determined for privately owned dogs undergoing clinical trials. In addition, the recording of accelerometer-based duration of locomotor activity showed strong and complementary agreement with the biomechanical limb function. The translation potential of these models to the human OA condition is underlined. A preclinical testing protocol which combines the dog model of experimental OA induced by cranial cruciate ligament transection and the Dog model of naturally occurring OA offers the opportunity to further investigate the structural and functional benefits of disease-modifying strategies. Ultimately, a better prediction of outcomes for human clinical trials would be brought.

Rivaroxaban demonstrates in vitro anticoagulant effects in canine plasma.

Rivaroxaban is an oral direct factor X inhibitor used in human thrombotic disorders and its oral administration makes it an attractive potential anticoagulant for dogs. The objective of this study was to evaluate the in vitro anticoagulant effect of rivaroxaban on canine pooled platelet-poor plasma (PPP). Pooled PPP was collected from 20 healthy adult Beagle dogs. Aliquots of pooled citrated PPP were treated in vitro with DMSO solutions of rivaroxaban (98% purity) to obtain 19 final concentrations ranging from 0 to 1000 mg/L of drug. Samples were immediately submitted for the following coagulation assays: prothrombin time (PT), activated partial thromboplastin time (aPTT), tissue factor-induced thrombin generation and anti-factor Xa activity. Concentration-effect data were analyzed with various nonlinear regression models for stimulatory or inhibitory effects. Rivaroxaban caused a concentration-dependent prolongation of all coagulation parameters. Rivaroxaban concentration for 50% baseline inhibition of the propagation phase of thrombin (rate index) was 0.024 mg/L, and for 50% baseline inhibition of the optical density in the anti-factor Xa activity assay was 0.053 mg/L. At these concentrations, PT and aPTT remained within the reference range. Two-fold prolongation from baseline of PT and aPTT was achieved with higher concentrations, i.e. 1.24 and 1.69 mg/L, respectively. Thrombin generation was completely suppressed by concentrations ≥0.8 mg/L. In conclusion, rivaroxaban showed an in vitro concentration-dependent anticoagulant effect on canine plasma. Thrombin generation and anti-factor Xa activity were more sensitive and accurate than PT and aPTT in detecting the anticoagulant effect of rivaroxaban.

Effect of a diet enriched with green-lipped mussel on pain behavior and functioning in dogs with clinical osteoarthritis.

This study aimed to establish the effect of a diet enriched with green-lipped mussel (GLM) on pain and functional outcomes in osteoarthritic dogs. Twenty-three client-owned dogs with osteoarthritis (OA) were fed a balanced control diet for 30 d and then a GLM-enriched balanced diet for the next 60 d. We assessed peak vertical force (PVF), which is considered to be the gold standard method, at Day (D)0 (start), D30 (end of control diet), and D90 (end of GLM-enriched diet). The owners completed a client-specific outcome measure (CSOM), which is a pain questionnaire, once a week. Motor activity (MA) was continuously recorded in 7 dogs for 12 wk. Concentrations of plasma omega-3 fatty acids were quantified as indicative of diet change. Statistical analyses were linear-mixed models and multinomial logistic regression for repeated measures. The GLM diet (from D30 to D90) resulted in an increase in concentrations of plasma omega-3 fatty acids (P < 0.016) and improvement of PVF (P = 0.003). From D0 to D30, PVF did not significantly change (P = 0.06), which suggests that the GLM diet had a beneficial effect on gait function. Moreover, PVF (P = 0.0004), CSOM (P = 0.006), and MA (P = 0.02) improved significantly from D0 to D90. In general, the balanced control diet could have contributed to reduced OA symptoms, an effect that was subsequently amplified by the GLM diet.

L'objectif de cette étude était d'établir l'effet d'une diète équilibrée enrichie en moule verte (GLM) avec des évaluations fonctionnelles et de douleur sur des chiens arthrosiques. Vingt-trois chiens arthrosiques de propriétaires (région de Montréal, QC) ont été nourris d'abord avec une diète équilibrée contrôle pendant 30 j., puis avec la diète enrichie en GLM pour les 60 j. suivants. Les évaluations incluaient le pic de force verticale (PFV), considéré comme la méthode étalon, au Jour (J)0 (inclusion), J30 (fin de la diète contrôle) et J90 (fin de la diète GLM). Les propriétaires ont complété de manière hebdomadaire une échelle de mesure spécifique à chaque client (CSOM), qui est un questionnaire de quantification de la douleur. L'activité motrice (AM) a été enregistrée en continu sur 7 chiens pour toute la durée de l'étude (12 sem.). Les concentrations plasmatiques d'acides gras oméga-3 ont été quantifiées en tant que marqueurs de changement de diètes. Les analyses statistiques furent des modèles linéaires-mixtes et une régression logistique multinomiale pour mesures répétées. La diète GLM (de J30 à J90) augmenta les concentrations plasmatiques d'acides gras oméga-3 (P < 0,016) ainsi que le PFV (P = 0,003). De J0 à J30, les changements de PFV furent non-significatifs (P = 0,06), ce qui suggère que la diète GLM a eu un effet thérapeutique sur la fonction biomécanique. De plus, PFV (P = 0,0004), CSOM (P = 0,006) et AM (P = 0,02) s'améliorèrent significativement de J0 à J90. De manière globale, il est possible que la diète équilibrée contrôle ait contribué à améliorer les signes d'arthrose, un effet qui fut amplifié par la suite avec la diète GLM.(Traduit par Docteur Eric Troncy).

Validation of orthopedic postoperative pain assessment methods for dogs: a prospective, blinded, randomized, placebo-controlled study.

In the context of translational research, there is growing interest in studying surgical orthopedic pain management approaches that are common to humans and dogs. The validity of postoperative pain assessment methods is uncertain with regards to responsiveness and the potential interference of analgesia. The hypothesis was that video analysis (as a reference), electrodermal activity, and two subjective pain scales (VAS and 4A-VET) would detect different levels of pain intensity in dogs after a standardized trochleoplasty procedure. In this prospective, blinded, randomized study, postoperative pain was assessed in 25 healthy dogs during a 48-hour time frame (T). Pain was managed with placebo (Group 1, n = 10), preemptive and multimodal analgesia (Group 2, n = 5), or preemptive analgesia consisting in oral tramadol (Group 3, n = 10). Changes over time among groups were analyzed using generalized estimating equations. Multivariate regression tested the significance of relationships between pain scales and video analysis. Video analysis identified that one orthopedic behavior, namely 'Walking with full weight bearing' of the operated leg, decreased more in Group 1 at T24 (indicative of pain), whereas three behaviors indicative of sedation decreased in Group 2 at T24 (all p<0.004). Electrodermal activity was higher in Group 1 than in Groups 2 and 3 until T1 (p<0.0003). The VAS was not responsive. 4A-VET showed divergent results as its orthopedic component (4A-VETleg) detected lower pain in Group 2 until T12 (p<0.0009), but its interactive component (4A-VETbeh) was increased in Group 2 from T12 to T48 (p<0.001). Concurrent validity established that 4A-VETleg scores the painful orthopedic condition accurately and that pain assessment through 4A-VETbeh and VAS was severely biased by the sedative side-effect of the analgesics. Finally, the video analysis offered a concise template for assessment in dogs with acute orthopedic pain. However, subjective pain quantification methods and electrodermal activity need further investigation.

Identification of a new cell line permissive to porcine reproductive and respiratory syndrome virus infection and replication which is phenotypically distinct from MARC-145 cell line.

BACKGROUND: Airborne transmitted pathogens, such as porcine reproductive and respiratory syndrome virus (PRRSV), need to interact with host cells of the respiratory tract in order to be able to enter and disseminate in the host organism. Pulmonary alveolar macrophages (PAM) and MA104 derived monkey kidney MARC-145 cells are known to be permissive to PRRSV infection and replication and are the most studied cells in the literature. More recently, new cell lines developed to study PRRSV have been genetically modified to make them permissive to the virus. The SJPL cell line origin was initially reported to be epithelial cells of the respiratory tract of swine. Thus, the goal of this study was to determine if SJPL cells could support PRRSV infection and replication in vitro. RESULTS: The SJPL cell growth was significantly slower than MARC-145 cell growth. The SJPL cells were found to express the CD151 protein but not the CD163 and neither the sialoadhesin PRRSV receptors. During the course of the present study, the SJPL cells have been reported to be of monkey origin. Nevertheless, SJPL cells were found to be permissive to PRRSV infection and replication even if the development of the cytopathic effect was delayed compared to PRRSV-infected MARC-145 cells. Following PRRSV replication, the amount of infectious viral particles produced in SJPL and MARC-145 infected cells was similar. The SJPL cells allowed the replication of several PRRSV North American strains and were almost efficient as MARC-145 cells for virus isolation. Interestingly, PRRSV is 8 to 16 times more sensitive to IFNα antiviral effect in SJPL cell in comparison to that in MARC-145 cells. PRRSV induced an increase in IFNß mRNA and no up regulation of IFNα mRNA in both infected cell types. In addition, PRRSV induced an up regulation of IFNγ and TNF-α mRNAs only in infected MARC-145 cells. CONCLUSIONS: In conclusion, the SJPL cells are permissive to PRRSV. In addition, they are phenotypically different from MARC-145 cells and are an additional tool that could be used to study PRRSV pathogenesis mechanisms in vitro.

Tiludronate treatment improves structural changes and symptoms of osteoarthritis in the canine anterior cruciate ligament model.

INTRODUCTION: The aim of this prospective, randomized, controlled, double-blind study was to evaluate the effects of tiludronate (TLN), a bisphosphonate, on structural, biochemical and molecular changes and function in an experimental dog model of osteoarthritis (OA). METHODS: Baseline values were established the week preceding surgical transection of the right cranial/anterior cruciate ligament, with eight dogs serving as OA placebo controls and eight others receiving four TLN injections (2 mg/kg subcutaneously) at two-week intervals starting the day of surgery for eight weeks. At baseline, Week 4 and Week 8, the functional outcome was evaluated using kinetic gait analysis, telemetered locomotor actimetry and video-automated behaviour capture. Pain impairment was assessed using a composite numerical rating scale (NRS), a visual analog scale, and electrodermal activity (EDA). At necropsy (Week 8), macroscopic and histomorphological analyses of synovium, cartilage and subchondral bone of the femoral condyles and tibial plateaus were assessed. Immunohistochemistry of cartilage (matrix metalloproteinase (MMP)-1, MMP-13, and a disintegrin and metalloproteinase domain with thrombospondin motifs (ADAMTS5)) and subchondral bone (cathepsin K) was performed. Synovial fluid was analyzed for inflammatory (PGE(2) and nitrite/nitrate levels) biomarkers. Statistical analyses (mixed and generalized linear models) were performed with an α-threshold of 0.05. RESULTS: A better functional outcome was observed in TLN dogs than OA placebo controls. Hence, TLN dogs had lower gait disability (P = 0.04 at Week 8) and NRS score (P = 0.03, group effect), and demonstrated behaviours of painless condition with the video-capture (P < 0.04). Dogs treated with TLN demonstrated a trend toward improved actimetry and less pain according to EDA. Macroscopically, both groups had similar level of morphometric lesions, TLN-treated dogs having less joint effusion (P = 0.01), reduced synovial fluid levels of PGE(2) (P = 0.02), nitrites/nitrates (P = 0.01), lower synovitis score (P < 0.01) and a greater subchondral bone surface (P < 0.01). Immunohistochemical staining revealed lower levels in TLN-treated dogs of MMP-13 (P = 0.02), ADAMTS5 (P = 0.02) in cartilage and cathepsin K (P = 0.02) in subchondral bone. CONCLUSION: Tiludronate treatment demonstrated a positive effect on gait disability and joint symptoms. This is likely related to the positive influence of the treatment at improving some OA structural changes and reducing the synthesis of catabolic and inflammatory mediators.

Involvement of the nitric oxide-soluble guanylyl cyclase pathway in the oxytocin-mediated differentiation of porcine bone marrow stem cells into cardiomyocytes.

Bone marrow stem cells (BMSCs) express cardiac markers in vitro and in vivo upon induction. Cardiomyogenic differentiation of embryonic stem cells induced by oxytocin (OT) involves the nitric oxide (NO)-soluble guanylyl cyclase (sGC) pathway. Also, OT improved cardiomyogenic differentiation of porcine BMSCs (pBMSCs). Here, we document the role of NO pathway in OT-mediated cardiomyogenic differentiation of pBMSCs obtained from bone marrow aspirates of juvenile pigs. Cells were exposed (OT cells) or not (control cells) to OT, in presence or absence of a NO synthase inhibitor (L-NAME) and a sGC inhibitor (ODQ). Gene (RT-PCR) and protein expression (immunocytochemistry) of NOS was up-regulated after OT induction. Exposure of OT cells to L-NAME, ODQ, or both, leaded to a significant reduction in cardiac troponin I transcripts, and protein (Western Blot) expression. For the latter, ODQ looked more performing in inhibition than L-NAME. Expression of cardiac troponin T and myosin heavy chain (immunocytochemistry) was less abundant in OT cells exposed to inhibitors without apparent synergic effect between L-NAME and ODQ. In control cells, protein expression remained low. Moreover, OT-induced cell proliferation, and this effect was counteracted by NOS/sGC inhibitors. Inhibiting NO production and NO effector, sGC, affected the OT-mediated differentiation of pBMSCs, because abundance of cardiac proteins was reduced to levels similar to those observed in control cells. We propose that following treatment with OT, activation of NO pathway directs pBMSCs to a preferential cardiomyogenic phenotype and stimulates cell proliferation.

In growing pigs, chlortetracycline induces a reversible green bone discoloration and a persistent increase of bone mineral density dependent of dosing regimen.

We studied in growing pigs the effects of exposure to dietary chlortetracycline on bone mineral density (BMD) and bone color. Pigs were randomly allocated to a drug-free diet (n=48) or a diet fortified with 800 ppm of chlortetracycline, starting either at 28- or 84-d of age, and for either a 28- or 56-d duration (n=16 pigs/group). The lumbar vertebral discoloration and BMD of randomly chosen pigs were evaluated at 28-d intervals up to 168-d of age. The odds of bone discoloration increased with dosing duration and age at treatment onset, and decreased with the withdrawal time and age at treatment onset interaction (p < or = 0.001). The measured trabecular BMD linearly increased with age and squared treatment duration (p < or = 0.005). Therefore, TC-induced bone discoloration is reversible, and may be prevented with proper dosing regimen design. Moreover, TC induces a persistent increase on BMD that could be detected with quantitative computed tomography.