Comparison of lidocaine and lidocaine-xylazine for distal paravertebral anesthesia in dairy cattle.

OBJECTIVE: To determine the time of onset and duration of action of distal paravertebral blocks (DPB) in dairy cattle using lidocaine and lidocaine plus xylazine (LX). ANIMALS: 10 healthy adult Holstein cows. METHODS: Unilateral DPB were performed in 6 cows at L1, L2, and L4. They received 2 treatments (lidocaine and LX) in a blinded random crossover design. Due to treatment failure, 4 additional cows were enrolled. The lidocaine treatment received 1,800 mg (90 mL) of lidocaine, and treatment LX received 1,784 mg (89.2 mL) of lidocaine and 16 mg (0.8 mL) of xylazine. Anesthesia was assessed by response (rapid movements of the tail, directed movements of the feet, or turning of the head towards the site of the needle pricks) to 6 approximately 1-cm deep needle pricks to the paralumbar fossa with a 22-gauge hypodermic needle. The time of onset, duration of action, maximum sedation score, and average heart rate (HR) were compared between treatments. RESULTS: Duration of anesthesia was significantly prolonged after DPB in cows treated with LX (251.6 ± 96.94 minutes) compared to lidocaine (105.8 ± 35.9 minutes; P = .01). Treatment with LX was associated with significantly lower average heart rate (56 ± 3 beats/min) compared to cows treated with lidocaine (59 ± 3 beats/min; P = .045). The LX treatment was associated with mild sedation but was not significant (P = .063). CLINICAL RELEVANCE: The addition of xylazine to a lidocaine DPB provides a longer duration of anesthesia, is inexpensive and practical, and can be implemented with ease.

Red cabbage juice-mediated gut microbiota modulation improves intestinal epithelial homeostasis and ameliorates colitis.

Gut microbiota plays a crucial role in inflammatory bowel disease (IBD) and has therapeutic benefits. Thus, targeting the gut microbiota is a promising therapeutic approach for IBD treatment. We recently found that red cabbage juice (RCJ) ameliorates dextran sulfate sodium (DSS)-induced colitis in mice. However, the underlying mechanisms remain unknown. The current study investigated the modulation of gut microbiota in response to treatment with RCJ to ameliorate the DSS colitis. The initial results demonstrated that mice treated with DSS + RCJ showed increased body weight and decreased diarrhea and blood in feces compared to the DSS alone group. RCJ ameliorated colitis by regulating the intestinal barrier function by reducing the number of apoptotic cells, improving colonic protective mucin, and increasing tight junction protein in RCJ + DSS groups compared to the DSS group. Short-gun metagenomic analysis revealed significant enrichment of short-chain fatty acid (SCFAs)-producing bacteria (Butyrivibrio, Ruminococcaceae, Acetatifactor muris, Rosburia Sp. CAG:303 , Dorea Sp. 5-2) increased PPAR-© activation, leading to repression of the nuclear factor κB (NFκB) signaling pathway, thus decreasing the production of crucial inflammatory cytokines and chemokines in the RCJ + DSS groups compared to the DSS group. Pathway abundance analysis showed an increased abundance of the SCFA pathway, reduced histidine degradation ( Bacteroides sartorii, and Bacteroides caecimuris ), and LCFA production in the RCJ+DSS treated group, suggesting the promotion of good colonic health. Furthermore, increased T-reg (FOXP3+) cells in the colon were due to SCFAs produced by the gut microbiota, which was corroborated by an increase in IL-10, a vital anti-inflammatory cytokine. Thus, our study provides the first evidence that RCJ ameliorates colonic inflammation by modulating the gut microbiota.

Pelvic limb anesthesia and analgesia in dogs undergoing tibial plateau leveling osteotomy (TPLO): A survey of board-certified anesthesiologists.

OBJECTIVE: To report the locoregional anesthesia and analgesia preferences of veterinary anesthesiologists for use in dogs undergoing a TPLO and determine any association with specialty college, time from board-certification, or employment sector. STUDY DESIGN: Cross sectional study. SAMPLE POPULATION: Diplomates of the American (ACVAA) and European (ECVAA) Colleges of Veterinary Anesthesia and Analgesia. METHODS: An electronic survey was distributed to diplomates and responses were used to determine associations between preferred methods. RESULTS: The survey response rate was 28% (141/500) with 69% (97/141) of ACVAA diplomates and 31% of diplomates with ECVAA (44/141) certification. Peripheral nerve block (PNB) was preferred by 79% (111/141) of all diplomates, lumbosacral epidural (LE) by 21% (29/141), and peri-incisional infiltration (PI) by <1% (1/141). There was no association (p = .283) with specialty college. There was an association (p < .001) with time from board-certification with increased preference for LE when >10-years from certification and PI preferred by only those board-certified >20-years ago. There was an association with employment sector (p = .003) with more academic diplomates preferring LE. Anesthesiologists reported that treatment decisions were affected by various factors including time pressure and surgeon influence. CONCLUSION: Diplomates of ACVAA and ECVAA prefer PNB as the locoregional method of pelvic limb anesthesia in dogs undergoing TPLO. A greater percentage of newer and private practice diplomates prefer PNB while a larger percentage of senior and academic diplomates prefer LE. Decision making is multifactorial and includes perceived time pressure and surgeon influence. CLINICAL SIGNIFICANCE: Veterinary anesthesiologists prefer and frequently use PNB in dogs undergoing TPLO and surgeon influence may affect their chosen treatment.

MRI Evaluation of Gene Therapy in the Canine Model of Duchenne Muscular Dystrophy.

Magnetic resonance imaging (MRI) is a well-established and widely used technique to characterize and quantify skeletal and cardiac muscle changes in Duchenne muscular dystrophy (DMD). Recently, MRI has been explored to study disease progression and response to gene therapy in the canine DMD model. Using traditional sequences, delayed gadolinium enhancement, novel sequences, and spectroscopy, investigators have begun to (i) establish the baseline MRI characteristics of the muscles in normal and affected dogs and (ii) evaluate gene therapy outcomes in treated dogs. As a noninvasive assay, MRI offers an excellent opportunity to study longitudinal muscle changes in long-term gene therapy studies in the canine model. In this chapter, we outline the MRI method used to study DMD in the canine model.

Red Cabbage Juice-Mediated Gut Microbiota Modulation Improves Intestinal Epithelial Homeostasis and Ameliorates Colitis.

Gut microbiota plays a crucial role in inflammatory bowel diseases (IBD) and can potentially prevent IBD through microbial-derived metabolites, making it a promising therapeutic avenue. Recent evidence suggests that despite an unclear underlying mechanism, red cabbage juice (RCJ) alleviates Dextran Sodium Sulfate (DSS)-induced colitis in mice. Thus, the study aims to unravel the molecular mechanism by which RCJ modulates the gut microbiota to alleviate DSS-induced colitis in mice. Using C57BL/6J mice, we evaluated RCJ's protective role in DSS-induced colitis through two cycles of 3% DSS. Mice were daily gavaged with PBS or RCJ until the endpoint, and gut microbiota composition was analyzed via shotgun metagenomics. RCJ treatment significantly improved body weight (p ≤ 0.001), survival in mice (p < 0.001) and reduced disease activity index (DAI) scores. Further, RCJ improved colonic barrier integrity by enhancing the expression of protective colonic mucins (p < 0.001) and tight junction proteins (p ≤ 0.01) in RCJ + DSS-treated mice compared to the DSS group. Shotgun metagenomic analysis revealed an enrichment of short-chain fatty acids (SCFAs)-producing bacteria (p < 0.05), leading to increased Peroxisome Proliferator-Activated Receptor Gamma (PPAR-γ) activation (p ≤ 0.001). This, in turn, resulted in repression of the nuclear factor κB (NFκB) signaling pathway, causing decreased production of inflammatory cytokines and chemokines. Our study demonstrates colitis remission in a DSS-induced mouse model, showcasing RCJ as a potential modulator for gut microbiota and metabolites, with promising implications for IBD prevention and treatment.

Effect of Midazolam on Vestibular Signs in Two Geriatric Dogs with Vestibular Disease.

An abrupt balance impairment, including leaning, falling, and rolling, occurred after IV administration of 0.2 mg/kg midazolam as a preanesthetic medication in two geriatric dogs with a history of nystagmus and head tilt. In the second case, leaning, falling, and rolling recurred after recovery from general anesthesia but gradually ceased after IV administration of 0.01 mg/kg flumazenil. These two cases suggest that the IV administration of midazolam was responsible for the balance impairment in dogs who were suspected to have idiopathic peripheral vestibular disease.

Ketosis Ameliorates Renal Cyst Growth in Polycystic Kidney Disease.

Mild reduction in food intake was recently shown to slow polycystic kidney disease (PKD) progression in mouse models, but whether the effect was due to solely reduced calories or some other aspect of the diet has been unclear. We now show that the benefit is due to the induction of ketosis. Time-restricted feeding, without caloric reduction, strongly inhibits mTOR signaling, proliferation, and fibrosis in the affected kidneys in a PKD rat model. A ketogenic diet had a similar effect and led to regression of renal cystic burden. Acute fasting in rat, mouse, and feline models of PKD results in rapid reduction of cyst volume, while oral administration of the ketone ß-hydroxybutyrate (BHB) in rats strongly inhibits PKD progression. These results suggest that cystic cells in PKD are metabolically inflexible, which could be exploited by dietary interventions or supplementation with BHB, representing a new therapeutic avenue to treat PKD.

Intravenous adipose-derived mesenchymal stem cell therapy for the treatment of feline asthma: a pilot study.

OBJECTIVES: The aim of this study was to evaluate the feasibility and efficacy of serially administered adipose-derived mesenchymal stem cells (MSCs) in an experimental feline asthma model. METHODS: Allergic asthma was acutely induced with Bermuda grass allergen in six purpose-bred cats. Five intravenous infusions of allogeneic MSCs (n = 4; MSC-treated) or saline (n = 2; placebo-treated) were administered over the first 130 days after asthma induction. Infusions contained 2 × 106, 4 × 106, 4.7 × 106, 1 × 107 and 1 × 107 cryopreserved MSCs/cat. For thoracic imaging additional cats were enrolled as control groups: four untreated, experimentally asthmatic cats (combined with placebo-treated cats), and six healthy, non-asthmatic cats. Outcome measures included airway eosinophilia, pulmonary mechanics, thoracic computed tomography and several immunologic assays. RESULTS: Cats were assessed for 9 months after treatment. At early points, airway eosinophil percentage was not affected by MSC administration (post-treatment average of days 12, 26, 47, 108 and 133 in MSC-treated cats was 41 ± 15% and in placebo-treated cats it was 34 ± 16%). By month 9, eosinophil percentages in all MSC-treated cats decreased to normal reference intervals (MSC-treated 6%; placebo-treated 20%; normal <17%). Diminished airway hyper-responsiveness was noted in all MSC-treated compared with placebo-treated cats at day 133 (dose of methacholine to double baseline airway resistance: MSC-treated median 22.9 mg/ml [range 6.4-64.0]; individual placebo-treated cats 1.1 and 5.0 mg/ml). Lung attenuation (mean ± SEM MSC-treated -865 ± 12 Hounsfield units [HU]; untreated asthmatics -820 ± 11 HU; P = 0.004) and bronchial wall thickening scores (median [interquartile range] MSC-treated 0 [0-1.5]; untreated asthmatic 11.6 [7.3-27.3]; P = 0.010) were significantly reduced in MSC-treated vs untreated asthmatic cats, consistent with decreased airway remodeling at month 9. No clear immunologic mechanisms by which MSCs act were determined. CONCLUSIONS AND RELEVANCE: MSCs may have a delayed effect in reducing airway inflammation, airway hyper-responsiveness and remodeling in experimentally induced asthmatic cats. Results warrant additional investigation of MSC therapy for asthma in cats.

Chronic neurokinin-1 receptor antagonism fails to ameliorate clinical signs, airway hyper-responsiveness or airway eosinophilia in an experimental model of feline asthma.

OBJECTIVES: Feline allergic asthma is a common chronic lower airway disease characterized by clinical signs attributed to eosinophilic inflammation, airway hyper-responsiveness (AHR) and airway remodeling. Tachykinins released from sensory nerves and immune cells bind neurokinin-1 (NK-1) receptors in the lung. The resultant neurogenic airway inflammation has been implicated in asthma pathogenesis. In mouse models and spontaneous human asthma, NK receptor antagonists reduce bronchospasm and inflammation. We hypothesized that chronic administration of maropitant, an NK-1 receptor antagonist, would decrease clinical signs of asthma, AHR and eosinophilic inflammation in experimentally asthmatic cats. METHODS: Cats (n = 6) induced to have asthma using Bermuda grass allergen (BGA) were enrolled in a randomized, prospective, placebo-controlled crossover design study. Cats received either oral maropitant (2 mg/kg) or placebo q48h for 4 weeks; following a 2 week washout, cats were crossed-over to the alternate treatment. Study endpoints included subjective clinical scoring systems after BGA challenge, ventilator-acquired pulmonary mechanics to assess AHR after bronchoprovocation with methacholine, and collection of bronchoalveolar lavage fluid to quantify airway eosinophilia. Statistical analysis was performed using a Mann-Whitney rank sum test with P <0.05 considered significant. RESULTS: Administration of maropitant for 1 month in experimentally asthmatic cats produced no significant difference in clinical scoring scheme (P = 0.589 and P = 1.0), AHR (P = 0.818) or airway eosinophilia (P = 0.669) compared with placebo. CONCLUSIONS AND RELEVANCE: Chronic administration of maropitant was ineffective at blunting clinical signs, AHR and airway eosinophilia in experimental feline asthma and thus cannot be recommended as a novel treatment for this disorder.

Acute neurokinin-1 receptor antagonism fails to dampen airflow limitation or airway eosinophilia in an experimental model of feline asthma.

OBJECTIVES: Feline allergic asthma is a chronic inflammatory disorder of the lower airways that may manifest with acute, life-threatening clinical signs. Tachykinins released from sensory nerves and immune cells binding neurokinin (NK)-1, NK-2 and NK-3 receptors have been implicated in asthma pathogenesis. Maropitant, an NK-1 receptor antagonist, blocks neuroimmune pathways and may be a viable treatment option for cats in asthmatic crisis. Using an experimental chronic allergic feline asthma model, we hypothesized that a single dose of maropitant given immediately after allergen challenge would blunt clinical signs, airway hyperresponsiveness (AHR) and airway eosinophilia. METHODS: Cats (n = 7) induced to have an asthmatic phenotype using Bermuda grass allergen (BGA) were enrolled in a prospective, placebo-controlled crossover design study. Cats randomly received maropitant (2 mg/kg SC) or placebo (saline SC) immediately post-BGA challenge, followed 12 h later by pulmonary mechanics testing and measurement of airway eosinophils. After a 2 week washout, cats were crossed-over to the alternate treatment. Study endpoints included subjective clinical scoring systems post-BGA challenge, ventilator-acquired pulmonary mechanics to assess AHR after bronchoprovocation with methacholine and collection of bronchoalveolar lavage fluid to quantify airway eosinophilia. Data were analyzed using a Mann-Whitney rank sum test with P <0.05 considered significant. RESULTS: A single injection of maropitant failed to diminish clinical composite score (P = 0.902), visual analogue scale scoring (P = 0.710), AHR (P = 0.456) or airway eosinophilia (P = 0.165) compared with placebo. CONCLUSIONS AND RELEVANCE: A single injection of maropitant given immediately post-allergen challenge was ineffective at blunting clinical signs, AHR and airway eosinophilia, and cannot be recommended as treatment for feline status asthmaticus.

Morphine and buprenorphine do not alter leukocyte cytokine production capacity, early apoptosis, or neutrophil phagocytic function in healthy dogs.

Opioids have immunomodulatory properties in many species, but there is little information pertaining to these properties in dogs. Our objective was to compare the in vivo effects of morphine, buprenorphine, and control solution on innate immune system function and apoptosis in healthy dogs. Six adult dogs received a 24-hour infusion of morphine, buprenorphine, or control solution (saline) in a randomized, controlled, crossover block design. Leukocyte apoptosis, phagocytosis, and oxidative burst were evaluated using flow cytometry. Lipopolysaccharide, lipoteichoic acid, and peptidoglycan-stimulated leukocyte production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 were determined using canine specific multiplex assays. No significant treatment effects were detected among groups. These data suggest that healthy dogs could be less sensitive to the immunomodulatory effects of acute opioid administration compared with other species. Larger investigations in healthy and immunologically challenged dogs are recommended prior to application of these results in clinical patients.

The TRPV1 receptor agonist capsaicin is an ineffective bronchoprovocant in an experimental model of feline asthma.

OBJECTIVES: Airway hyper-responsiveness (AHR), a key feature of feline asthma, can be measured using bronchoprovocation testing. Limitations of both direct and indirect bronchoprovocants evaluated to date in experimental feline asthma have led to a search for a more specific indirect bronchoprovocant (ie, one which relies on existing inflammatory cells or activated neural pathways in diseased but not healthy airways). We hypothesized that capsaicin, a transient receptor potential cation channel subfamily V member 1 agonist, would lead to dose-responsive increases in airway resistance as measured by ventilator-acquired pulmonary mechanics in experimentally asthmatic cats. METHODS: Five cats induced to have asthma using Bermuda grass allergen (BGA) were studied. Twenty-four hours after aerosol challenge of BGA, cats were anesthetized and underwent neuromuscular blockade for ventilator-acquired pulmonary mechanics. Cats were monitored with pulse oximetry for hemoglobin desaturation. Parameters recorded on a breath-by-breath basis on the ventilator included airway resistance (Raw) and compliance. Saline at baseline and 10-fold increasing concentrations of capsaicin (0.4-4000.0 µM) were aerosolized for 30 s and data collected for 4 mins between doses. The intended endpoint of the study was a doubling in baseline airway resistance, halving of compliance or oxygen desaturation <75%. RESULTS: All cats completed the trial, reaching the highest dose of capsaicin without reaching any of the aforementioned endpoints. No biologically significant alteration in any other pulmonary mechanics parameter was noted. CONCLUSIONS AND RELEVANCE: Capsaicin does not appear to be an effective bronchoprovocant in a feline asthma model.

Injectable gelatin used as hemostatic agent to stop pedicle bleeding in long deformity surgical procedures: does it embolize?

STUDY DESIGN: Prospective porcine animal model. OBJECTIVE: Determine if injecting FloSeal into pedicles for hemostasis causes emboli. SUMMARY OF BACKGROUND DATA: Bleeding from spinal deformity cases can be substantial, especially when surgical procedures involve bilateral fixation at multiple segments. It is not unusual to observe hemorrhage from vascular pedicles during each step of pedicle screw tract preparation. When multiple fixation points are required, blood loss can be excessive. To minimize estimated blood loss and associated morbidity, surgeons have injected liquefied gelatin into pedicles after drilling, palpating, and/or tapping. FloSeal is one of the most popular commercially available injectable agents and we sought to investigate the potential for embolization when used as an intrapedicular hemostatic agent. METHODS: Two adult minipigs were anesthetized and underwent sequential bilateral pedicle cannulation from T-spine to sacrum. At every level, tracts were cannulated, palpated, and tapped. In every tract, FloSeal was injected into each pedicle until back pressure was detected on the syringe or to a maximum volume of 2 mL, then pedicle screws were inserted. The right ventricular outflow tract was visualized real time using transesophageal echocardiography. Postmortem evaluation of heart and lungs was performed. RESULTS: FloSeal injected into pedicles caused a consistent large showering of the right ventricular outflow tract in both pigs as visualized on intraoperative transesophageal echocardiography. A second large showering occurred during screw insertion after FloSeal was injected. Microscopic examination of lungs clearly identified amphophilic amorphous material in many small vessels consistent with FloSeal. CONCLUSION: This study suggests caution when injecting gelatin hemostatic agents into pedicles to stop bleeding during spinal surgery as we saw clear evidence of fat and gelatin emboli when used in this animal model. Further investigation into how to minimize this embolic showering may help the cardiopulmonary at risk patient who requires spinal surgery, especially when multiple points of pedicle screw fixation are used. LEVEL OF EVIDENCE: N/A.

In-vitro immunosuppression of canine T-lymphocyte-specific proliferation with dexamethasone, cyclosporine, and the active metabolites of azathioprine and leflunomide in a flow-cytometric assay.

A high rate of mortality, expense, and complications of immunosuppressive therapy in dogs underscores the need for optimization of drug dosing. The purpose of this study was to determine, using a flow-cytometric assay, the 50% T-cell inhibitory concentration (IC50) of dexamethasone, cyclosporine, and the active metabolites of azathioprine (6-mercaptopurine) and leflunomide (A77 1726) in canine lymphocytes stimulated with concanavalin A (Con A). Whole blood was collected from 5 privately owned, healthy dogs of various ages, genders, and breeds. Peripheral blood mononuclear cells, obtained by density-gradient separation, were cultured for 72 h with Con A, a fluorochrome-tagged cell proliferation dye, and various concentrations of dexamethasone (0.1, 1, 10, 100, 1000, and 10 000 µM), cyclosporine (0.2, 2, 10, 20, 30, 40, 80, and 200 ng/mL), 6-mercaptopurine (0.5, 2.5, 50, 100, 250, and 500 µM), and A77 1726 (1, 5, 10, 25, 50, and 200 µM). After incubation, the lymphocytes were labeled with propidium iodide and an antibody against canine CD5, a pan T-cell surface marker. Flow cytometry determined the percentage of live, proliferating T-lymphocytes incubated with or without immunosuppressants. The mean (± standard error) IC50 was 3460 ± 1900 µM for dexamethasone, 15.8 ± 2.3 ng/mL for cyclosporine, 1.3 ± 0.4 µM for 6-mercaptopurine, and 55.6 ± 22.0 µM for A77 1722. Inhibition of T-cell proliferation by the 4 immunosuppressants was demonstrated in a concentration-dependent manner, with variability between the dogs. These results represent the initial steps to tailor this assay for individual immunosuppressant protocols for dogs with immune-mediated disease.

Un taux de mortalité élevé, le coût élevé, et les complications associés à la thérapie immunosuppressive chez les chiens font ressortir le besoin d'optimisation de la médication. L'objectif de la présente étude était de déterminer, au moyen d'une épreuve de cytométrie en flux, la concentration de dexaméthazone, de cyclosporine, et des métabolites actifs de l'azathioprine (6-mercaptopurine) et du leflunomide (A77 1726) inhibant 50 % des cellules T (IC50) de lymphocytes canins stimulés avec de la concanavaline A (Con A). Du sang entier fut prélevé de cinq chiens en santé, d'âges, de sexes et de races variés et appartenant à des propriétaires. Des cellules mononucléaires du sang périphérique, obtenues par séparation à l'aide d'un gradient de densité, furent cultivées pendant 72 h avec de la Con A, un colorant de prolifération cellulaire marqué avec un fluorochrome, et diverses concentrations de dexaméthazone (0,1, 1, 10, 100, 1000, et 10 000 µM), de cyclosporine (0,2, 2, 10, 20, 30, 40, 80, et 200 ng/mL), de 6-mercaptopurine (0,5, 2,5, 50, 100, 250, et 500 µM), et de A77 1726 (1, 5, 10, 25, 50, et 200 µM). Après incubation, les lymphocytes furent marqués avec de l'iodure de propidium et un anticorps dirigé contre CD5 canin, un marqueur de surface de toutes les cellules T. La cytométrie en flux a permis de déterminer le pourcentage de lymphocytes T vivants et en prolifération incubés avec ou sans agent immunosuppresseur. La moyenne (± écart-type) de l'IC50 était de 3460 ± 1900 µM pour la dexaméthazone, 15,8 ± 2,3 ng/mL pour la cyclosporine, 1,3 ± 0,4 µM pour la 6-mercaptopurine, et 55,6 ± 22,0 µM pour A77 1722. L'inhibition de la prolifération des cellules T par les quatre agents immunosuppresseurs fut démontrée comme étant dépendante de la concentration, avec une variabilité entre les chiens. Ces résultats représentent les étapes initiales pour adapter cet essai aux protocoles immunosuppresseurs individuels pour les chiens avec des maladies à médiation immunitaire.(Traduit par Docteur Serge Messier).

Quantitative assessment of the canine pupillary light reflex.

PURPOSE: To develop instrumentation and methods for thorough quantitative assessment of the pupillary light reflex (PLR) in dogs under varying stimulus conditions. METHODS: The PLR was recorded in normal Dachshunds using a custom system allowing full user control over stimulus intensity, color, and duration. Chemical restraint protocols were compared to determine which protocol provided for optimal baseline stability of pupil size and appropriate eye positioning. A series of white light stimuli of increasing intensity was used to elicit pupil constriction. Pupil images were concurrently recorded using continuous infrared illumination and an infrared-sensitive camera. The PLR was also recorded in response to blue and red stimuli. RESULTS: With injectable chemical restraint alone, spontaneous fluctuations in pupil size occurred independent of light stimulation, and spontaneous eye movements made it difficult to fully visualize the pupil. Combined injectable chemical and inhalation restraint provided a steady baseline pupil size throughout PLR assessment and allowed for stable positioning of the eye using a conjunctival stay suture. Robust PLRs were elicited with all light colors. PLR constriction amplitude increased with increasing flash intensity and ranged from 5% to 70%. CONCLUSIONS: A recording system and protocol have been developed to reliably quantify the canine PLR. The techniques and instrumentation will be useful for objective quantitative assessment of the PLR in dogs and other species in research applications and may be useful in clinical veterinary ophthalmology and neurology if PLR abnormalities detected with these procedures can be associated with specific diseases.

Nebulized lidocaine blunts airway hyper-responsiveness in experimental feline asthma.

Nebulized lidocaine may be a corticosteroid-sparing drug in human asthmatics, reducing airway resistance and peripheral blood eosinophilia. We hypothesized that inhaled lidocaine would be safe in healthy and experimentally asthmatic cats, diminishing airflow limitation and eosinophilic airway inflammation in the latter population. Healthy (n = 5) and experimentally asthmatic (n = 9) research cats were administered 2 weeks of nebulized lidocaine (2 mg/kg q8h) or placebo (saline) followed by a 2-week washout and crossover to the alternate treatment. Cats were anesthetized to measure the response to inhaled methacholine (MCh) after each treatment. Placebo and doubling doses of methacholine (0.0625-32.0000 mg/ml) were delivered and results were expressed as the concentration of MCh increasing baseline airway resistance by 200% (EC200Raw). Bronchoalveolar lavage was performed after each treatment and eosinophil numbers quantified. Bronchoalveolar lavage fluid (BALF) % eosinophils and EC200Raw within groups after each treatment were compared using a paired t-test (P <0.05 significant). No adverse effects were noted. In healthy cats, lidocaine did not significantly alter BALF eosinophilia or the EC200Raw. There was no difference in %BALF eosinophils in asthmatic cats treated with lidocaine (36±10%) or placebo (33 ± 6%). However, lidocaine increased the EC200Raw compared with placebo 10 ± 2 versus 5 ± 1 mg/ml; P = 0.043). Chronic nebulized lidocaine was well-tolerated in all cats, and lidocaine did not induce airway inflammation or airway hyper-responsiveness in healthy cats. Lidocaine decreased airway response to MCh in asthmatic cats without reducing airway eosinophilia, making it unsuitable for monotherapy. However, lidocaine may serve as a novel adjunctive therapy in feline asthmatics with beneficial effects on airflow obstruction.

Endotracheal nebulization of N-acetylcysteine increases airway resistance in cats with experimental asthma.

N-acetylcysteine (NAC), a mucolytic and antioxidant, is speculated to cause bronchoconstriction in cats when delivered via aerosol. We hypothesized that in cats with experimental asthma, aerosol delivery of NAC (400mg cumulative dose) via an endotracheal tube would increase airflow limitation as measured by ventilator-acquired mechanics. After endotracheal drug delivery, airway resistance and inspiratory plateau pressure (Pplat) measurements were obtained in six mechanically ventilated asthmatic cats. Results demonstrated significantly increased airway resistance (P=0.0007) compared with aerosolized saline control; Pplats were not significantly different (P=0.059). All cats exhibited at least one adverse effect: excessive airway secretions (n=3), spontaneous cough (n=2), unilateral strabismus (n=1) and post-anesthetic death (n=1). No adverse reactions were noted with saline aerosol; cough was noted in one cat with methacholine challenge. In conclusion, airway resistance and adverse reactions were documented in all cats after NAC aerosol delivery. Further studies must be performed to evaluate if it is an effective mucolytic and/or antioxidant in cats and to determine if bronchodilator pre-treatment will negate NAC-induced bronchoconstriction.

Effects of intracameral administration of α-chymotrypsin on intracapsular lens extraction and postoperative outcome in clinically normal dogs.

OBJECTIVE: To assess the intraoperative and postoperative clinical effects and histologic effects of intracameral administration of α-chymotrypsin in clinically normal dogs undergoing standard intracapsular lens extraction (ICLE). ANIMALS: 6 young adult male dogs without evidence of systemic or ocular disease. PROCEDURES: All dogs underwent bilateral ICLE 7 minutes following injection of 75 U of α-chymotrypsin or an identical volume (0.5 mL) of a commercially available balanced saline solution (BSS) into the posterior chamber of the eye. Ease of lens extraction was subjectively assessed and intraoperative intraocular hemorrhage and fibrin accumulation scored. For 27 days after surgery, ocular hyperemia and discharge, chemosis, corneal edema, hyphema, and aqueous flare were scored, and intraocular pressure (IOP) was measured. Thirty days after surgery, histologic evidence of anterior synechia, collapse of and inflammation within the iridocorneal angle, and iritis were scored. RESULTS: In 5 of 6 dogs, the surgeon was able to correctly identify the eye treated with α-chymotrypsin on the basis of ease of lens extraction. Mean intraoperative intraocular hemorrhage and fibrin scores for BSS-treated eyes were significantly higher than for α-chymotrypsin-treated eyes. Postoperatively, there were no significant differences between treatments for any clinical variables, including IOP Histologic scores were not significantly different between treatments for any variable. Vision was lost as a result of glaucoma in 1 α-chymotrypsin-treated eye and 1 BSS-treated eye. CONCLUSIONS AND CLINICAL RELEVANCE: Intracameral administration of 75 U of α-chymotrypsin 7 minutes before ICLE facilitated lensectomy without apparent adverse effects in clinically normal dogs.

Immunomodulatory effects of opioids.

OBJECTIVE: To review the immunomodulatory effects of opioids. DATA SOURCES: Original research publications and review articles using the PubMed search engine with the following keywords--opioids, morphine, immuomodulation, and immunosuppression. VETERINARY AND HUMAN DATA SYNTHESIS: Opioids have been shown to modulate the immune system in animal models by affecting both the acquired and innate arms of the immune system. Natural killer cell activity, T-cell proliferation, antibody production, phagocytic cell function, and cytokine production have all been shown to be affected by opioids. Many of these effects are reversed by opioid antagonists. Opioids have also been shown to induce sepsis in laboratory animals. Opioid administration alters immune parameters in healthy humans at analgesic doses and may increase the risk of infection in some patient populations. CONCLUSIONS: While opioids remain the most powerful and widely used analgesics available, their negative effects on the immune system are well established in the laboratory setting. Thoughtful consideration should be given to the use of certain opioids in critically ill patients, especially those with pre-existing immunocompromise.

Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure measurements in ill dogs.

OBJECTIVE: To compare blood pressure measurements obtained via ultrasonic Doppler flow monitor (DOP) and 2 oscillometric noninvasive blood pressure monitors (CAR and PAS) to invasive blood pressure (IBP) in hospitalized, conscious dogs with a range of blood pressures. DESIGN: Prospective clinical study. SETTING: University teaching hospital. ANIMALS: Eleven client-owned dogs aged between 4 months and 11.5 years (median 6 y), and weighing between 5.8 and 37.5 kg (median 30.2 kg). INTERVENTIONS: Blood pressure measurement. MEASUREMENTS AND MAIN RESULTS: Three consecutive measurements of systolic, diastolic, and mean arterial pressure (MAP) were recorded for each of the 3 indirect devices (only systolic for DOP), along with concurrent IBP measurements. The data were categorized into 3 groups: hypotensive (direct MAP<80 mm Hg), normotensive (80 mm Hgor=100 mm Hg), and hypertensive (direct MAP>100 mm Hg). Each indirect method was compared with the corresponding direct arterial pressure using the Bland-Altman method. Within the hypotensive group, each indirect method overestimated the corresponding IBP. Within the normotensive group all indirect systolic measurements and the PAS diastolic measurements underestimated the corresponding IBP. The remaining indirect measurements overestimated the corresponding IBP. Within the hypertensive group, DOP and CAR systolic measurements underestimated the corresponding IBP, and the remaining indirect measurements overestimated the corresponding IBP. In hypertensive dogs oscillometric systolic measurements were more accurate than MAP. In hypotensive dogs MAP measurements were more accurate than systolic measurements. All indirect measurements were most accurate in hypertensive dogs. CONCLUSIONS: The noninvasive blood pressure monitors in our study did not meet the validation standards set in human medicine. However, CAR diastolic and MAP measurements within the normotensive group, CAR MAP measurements within the hypertensive group, and PAS diastolic measurements in all groups were close to these standards. All indirect measurements showed greater bias during hypotension. Precision was poorer for all indirect systolic measurements than for MAP.