Assessment of a standing position during abdominal point-of-care ultrasound on abdominal fluid score in dogs.

OBJECTIVE: To assess the use of a standing position during abdominal point-of-care ultrasound (POCUS) examination when evaluating dogs for peritoneal effusion. DESIGN: Randomized prospective study over 17 months. SETTING: Single-center, university veterinary teaching hospital. ANIMALS: Thirty dogs presenting for acute abdominal disease. Eligibility included suspicion for free peritoneal effusion and the ability to stand. INTERVENTIONS: Dogs underwent standing abdominal POCUS, right lateral abdominal POCUS, and a full abdominal ultrasound. We originally had nothing listed. It now includes all three ultrasound evaluations that were performed for each patient. MEASUREMENTS AND MAIN RESULTS: Patients underwent both a right lateral and standing abdominal POCUS via a previously described abdominal focused assessment with sonography for trauma (A-FASTrl and A-FASTs, respectively) technique in a randomized and sequential order followed by a full abdominal ultrasound (AUS-full). The A-FASTs examination included a right flank location in addition to the following standard views: subxiphoid, left flank, urinary bladder, and umbilicus. Five-second cine loops were obtained at each location for each examination and reviewed in the order they were obtained. Locations for both A-FAST exams were interrogated in the same order every time. The cine loops were scored for the degree of peritoneal effusion based on a previously published abdominal fluid scoring system by a board-certified radiologist, radiology resident, and radiology intern. The overall abdominal fluid score (AFS) was compared to a subjective full abdominal ultrasound score given by a board-certified radiologist. Six dogs had no peritoneal effusion, 13 had a small volume (AFS 1 or 2), and 11 had a moderate to large volume (AFS 3 or 4). Excellent agreement (intraclass correlation coefficient) was found between the A-FASTs and A-FASTrl techniques (0.95, 0.93, 0.94), good agreement between A-FASTs and AUS-full (0.80, 0.77, 0.82), and good agreement between A-FASTrl and AUS-full (0.80, 0.82, 0.84). The interobserver agreement was good (0.87) for the A-FASTs technique and excellent (0.91) for the A-FASTrl technique. Mean observer agreement score was excellent (0.94) when evaluating A-FASTrl to A-FASTs, good (0.86) when evaluating A-FASTs to AUS-full, and good (0.87) when evaluating A-FASTrl to AUS-full. CONCLUSION: Performing a standing abdominal POCUS examination may be a valid option for identifying and quantifying peritoneal effusion in situations when a more traditional right lateral approach cannot be performed.

Ex vivo biomechanical evaluation of a bone-screw-fastener for tibial plateau leveling osteotomy.

Introduction: The objective of this study was to investigate the effect of a novel screw type on stiffness and failure characteristics of a tibial plateau leveling osteotomy (TPLO) construct under cyclic loading conditions. The authors hypothesized that bone-screw-fasteners (BSF) would result in superior biomechanical stability compared with locking buttress screws (LBS). Materials and Methods: Twelve pairs of canine cadaveric pelvic limbs were included in this ex vivo biomechanical study. A TPLO was performed using a 3.5mm locking TPLO plate and stabilized using either LBS or BSF. Cyclic loading was performed for 30,000 cycles at 4Hz with a peak-load of 1000N (50N valley). The cyclic test was then continued by stepwise incremental increase of peak-load at a rate of 75N per 500 cycles until failure. Results: Cycles to failure for LBS (44,260 ± 5,770) and BSF (41,540 ± 7,686) were not significantly different (p = 0.36). Maximum force for LBS (3,134 ± 797N) and BSF (2,940 ± 831N) was not significantly different either (p = 0.58). Dynamic stiffness for LBS (1,778 ± 932 N/mm) and BSF (1,574 ± 677 N/mm) was not significantly different (p = 0.58). Discussion: Stabilization of the TPLO with BSF provided similar biomechanical stability under cyclic axial loading conditions as the LBS. BSF may be an acceptable alternative to traditional locking screws for TPLO.

Evaluation of Clinicopathological Data, the Specific Feline Pancreatic Lipase Assay, and Abdominal Ultrasound as Severity Determinants in Cats with Pancreatitis.

Limited data exist to predict the severity of pancreatitis in cats. In this retrospective case series, we reviewed the medical records of 45 cats with SP from June 2014 to June 2019. Case definition was based on an internist's review of clinopathologic data, Spec fPL concentration, and AUS findings. Information extracted from the medical records included signalment, history, physical examination findings, selected clinicopathological data (total bilirubin, glucose, ALP, ALT, and total calcium), Spec fPL concentration, AUS images/clips, length of hospitalization, and survival data. Hazard ratios were used to evaluate the association between clinicopathological data, the Spec fPL assay, AUS findings, and the length of hospitalization. Clinicopathological abnormalities, the Spec fPL, and AUS abnormalities were not statistically associated with the length of hospitalization. Despite a lack of statistical significance, the hazard ratios suggest the potential that an elevated total bilirubin (hazard ratio (HR): 1.19), hypocalcemia (HR: 1.49), and an elevated Spec fPL concentration (HR: 1.54) could be associated with prolonged hospitalization, although additional studies would be needed to verify this. Additionally, hazard ratios suggest that AUS evidence of concurrent gallbladder (HR: 1.61) and gastric abnormalities (HR: 1.36) could be associated with prolonged hospitalization.

Retrospective analysis of immunosuppressive and anti-thrombotic protocols in nonassociative immune mediated hemolytic anemia in dogs.

BACKGROUND: Evidence supporting the effectiveness of therapeutic protocols for nonassociative immune-mediated hemolytic anemia (na-IMHA) is weak. HYPOTHESIS/OBJECTIVES: Investigate the efficacy of various drugs in na-IMHA. ANIMALS: Two hundred forty-two dogs. METHODS: Multi-institutional retrospective study (2015-2020). Immunosuppressive effectiveness was determined by time to packed cell volume (PCV) stabilization and duration of hospitalization through analysis by mixed model linear regression. Occurrence of disease relapse, death, and antithrombotic effectiveness, were analyzed using mixed model logistic regression. RESULTS: Use of corticosteroids vs a multi-agent protocol had no effect on time to PCV stabilization (P = .55), duration of hospitalization (P = .13), or case fatality (P = .06). A higher rate of relapse (P = .04; odds ratio: 3.97; 95% confidence interval [CI]: 1.06-14.8) was detected in dogs receiving corticosteroids (11.3%) during follow-up (median: 28.5 days, range: 0-1631 days) compared to multiple agents (3.1%) during follow up (median: 47.0 days, range: 0-1992 days). When comparing drug protocols, there was no effect on time to PCV stabilization (P = .31), relapse (P = .44), or case fatality (P = .08). Duration of hospitalization was longer, by 1.8 days (95% CI: 0.39-3.28 days), for the corticosteroid with mycophenolate mofetil group (P = .01) compared to corticosteroids alone. Use of clopidogrel vs multiple agents had no effect on development of thromboses (P ≥ .36). CONCLUSIONS AND CLINICAL IMPORTANCE: Addition of a second immunosuppressive agent did not alter immediate outcome measures but might be associated with a reduction in relapse. Use of multiple antithrombotic agents did not reduce incidence of thrombosis.

Medical Management of Canine Chronic Ulcerative Stomatitis Using Cyclosporine and Metronidazole.

Canine chronic ulcerative stomatitis (CCUS) is a spontaneously occurring, painful, and often debilitating condition of the oral cavity, with a suspected immune-mediated component. The response to pharmacological treatment is generally poor, thus the need to identify more effective medical therapies for this condition. This article describes a prospective clinical trial that was designed to evaluate the efficiency of a combination of cyclosporine and metronidazole in managing CCUS. The hypothesis was that a combination of cyclosporine and metronidazole would effectively minimize clinical signs associated with CCUS. Ten client-owned dogs with a biopsy-confirmed diagnosis consistent with CCUS were prescribed cyclosporine (5 mg/kg) for 1 week, followed by the addition of metronidazole (15-20 mg/kg), both administered orally once daily. The cyclosporine dosage interval was lengthened over time. Dogs were observed for a 6-month period and evaluated using a 32-point Canine Ulcerative Stomatitis Disease Activity Index (CUSDAI). Regular cyclosporine therapeutic drug monitoring was also conducted by the measurement of whole blood cyclosporine levels and the pharmacodynamic assessment of the T-cell expression of IL-2. The results demonstrated that a combination of cyclosporine and metronidazole was effective in minimizing the clinical signs of CCUS and in reducing CUSDAI scores. Neither blood cyclosporine levels nor the T-cell expression of IL-2 predicted improvement in clinical signs and CUSDAI scores, although there was a correlation between blood drug concentrations and the suppression of T-cell IL-2 expression. The evaluation of clinical signs and CUSDAI scores appears to be the most effective means of assessing response to therapy, and therapeutic drug level monitoring does not appear to be routinely indicated.

Sources of variance in the results of a commercial bovine immunoglobulin G radial immunodiffusion assay.

Radial immunodiffusion (RID) is used to quantify IgG concentration in neonatal beef or dairy calf serum; variability has been noted that may affect the precision and accuracy of assay results. We determined the source, range, and homogeneity of variance in the results of a commercial bovine IgG RID assay (Triple J Farm). To estimate the variance in the precipitin ring diameter, we used 6 sera, measured 28 times across 8 plates and 4 lots, and 3 standards with known IgG concentrations, measured 75 times across 69 plates and 5 lots. The source of diameter variance was determined using variance partition coefficients for lot, plate, and repetition. We used 11 different methods to generate standard curves to convert RID precipitin ring diameters to IgG concentrations. The Levene test of homogeneity of variance (α = 0.1) was used to evaluate the equality of variance between the standards or serum precipitin ring diameters and calculated IgG concentrations. Lot and plate contributed minimally to the diameter variance. Precipitin ring diameters had equal variance. Calculated IgG concentrations for serum not requiring dilution had equal variance. A linear equation from aggregated standards, performed within the same day, had greater accuracy for the calculated IgG concentrations of the standards compared to other equation methods. Regardless of standard curve methodology or IgG concentration, variability inherent to the assay limits its clinical usefulness.

Anticoagulant effects of rivaroxaban, prednisone, alone and in combination, in healthy dogs.

BACKGROUND: The potential effects of glucocorticoid administration on rivaroxaban's anticoagulant bioactivity in dogs, and an appropriate rivaroxaban dosage regimen for dogs receiving glucocorticoid therapy are unknown. HYPOTHESIS/OBJECTIVES: The objective was to determine whether glucocorticoid administration influences the anticoagulant effects of rivaroxaban in healthy dogs. We hypothesized that administration of rivaroxaban and prednisone would reduce the anticoagulant intensity compared with rivaroxaban alone. ANIMALS: Nine healthy dogs. METHODS: Randomized, cross-over study. Dogs were administered prednisone (2 mg/kg, PO, q24h), rivaroxaban (1.5 mg/kg, PO, q24h), or prednisone and rivaroxaban, and the coagulation status was evaluated using prothrombin time (PT), and rivaroxaban-calibrated anti-Xa activity (RIVA, results were log10 transformed for analysis), before drug administration and on days 2, 4, and 8. Linear mixed models and correlation were used to evaluate associations in variables (P < .05 was considered significant). RESULTS: There were no differences in RIVA results for the rivaroxaban and prednisone/rivaroxaban groups on day 8 (P = .599, median 87 [range 45-156] to 167 [56-333], respectively, median difference 90 ng/mL [95% CI:87.3-161.8]) There was a strong correlation between RIVA and PT results when days 2, 4, and 8 were combined (r = .846, P < .001), and increased during drug administration, day 2 (r = .810, P < .001), day 4 (r = .863, P < .001), and day 8 (r = .885, P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Clotting times in the PT correlate with rivaroxaban levels and may prove useful for drug monitoring. Prednisone administration had no apparent influence on the anticoagulant effects of rivaroxaban in healthy dogs, suggesting that combined therapy will not require dosage adjustments.

Epidemiology's Adoption of System Dynamics is a Natural Extension of Population Thinking.

Epidemiologists have adopted systems thinking as an approach to understanding why health conditions occur in animal populations beyond the knowledge of simple linear relationships. Beef production systems are complex adaptive systems and decisions and policies throughout the system can positively or negatively affect the health of cattle. Those decisions may occur far removed in time or place from the health event and may be logical in the context of other factors in the system. Causal loop diagrams and stock and flow models are tools for sharing and testing thoughts about the ways systems might behave.

Assessment of Diversity of Antimicrobial Resistance Phenotypes and Genotypes of Mannheimia haemolytica Isolates From Bovine Nasopharyngeal Swabs.

The threat of bovine respiratory disease (BRD) for cattle operations is exacerbated by increasing prevalence of antimicrobial resistance (AMR) in Mannheimia haemolytica, a leading cause of BRD. Characterization of AMR in M. haemolytica by culture and susceptibility testing is complicated by uncertainty regarding the number of colonies that must be selected to accurately characterize AMR phenotypes (antibiograms) and genotypes in a culture. The study objective was to assess phenotypic and genotypic diversity of M. haemolytica isolates on nasopharyngeal swabs (NPS) from 28 cattle at risk for BRD or with BRD. NPS were swabbed onto five consecutive blood agar plates; after incubation up to 20 M. haemolytica colonies were selected per plate (up to 100 colonies per NPS). Phenotype was determined by measuring minimum inhibitory concentrations (MIC) for 11 antimicrobials and classifying isolates as resistant or not. Genotype was indirectly determined by matrix-assisted laser desorption/ionization time of flight mass spectroscopy (MALDI-TOF MS). NPS from 11 of 28 cattle yielded at least one M. haemolytica isolate; median (range) of isolates per NPS was 48 (1-94). NPS from seven cattle yielded one phenotype, 3 NPS yielded two, and 1 NPS yielded three; however, within a sample all phenotypic differences were due to only one MIC dilution. On each NPS all M. haemolytica isolated were the same genotype; genotype 1 was isolated from three NPS and genotype two was isolated from eight. Diversity of M. haemolytica on bovine NPS was limited, suggesting that selection of few colonies might adequately identify relevant phenotypes and genotypes.

Pathological and Ultrastructural Characterization of an Edwardsiella ictaluri Triple hemR Mutant.

Enteric septicemia of catfish, which is caused by Edwardsiella ictaluri, is detrimental to farmed Channel Catfish Ictalurus punctatus. The hemin receptor HemR is involved in binding and uptake of heme into bacteria. Here, we explored pathological and ultrastructural changes in catfish fry that were immunized with a triple hemR mutant of E. ictaluri and challenged with wild-type E. ictaluri (EiWT) 28 d after immunization. Following immunization, pathological changes in the triple hemR-immunized fry were less severe compared to the EiWT-exposed control fry. Widely disseminated bacteria and severe necrosis in most organs, especially the kidney and spleen, were detected in both groups at days 4, 5, and 6. Multifocal granulomatous encephalitis with bacteria was seen in hemR-immunized fry at days 21 and 28 and in EiWT-exposed control fry at day 14. Phagocytic cells in the kidney and spleen of EiWT-exposed control fry contained more replicating bacteria compared to hemR-immunized fry. During the EiWT challenge of immunized fry, a robust immune response was observed in the triple hemR-immunized fry compared to the sham-vaccinated group. Many activated phagocytic cells were detected in the kidney and spleen with fragmented or no bacteria in the triple hemR-immunized fry. Our data suggested that virulence of triple hemR was lower and the onset of the lesions was delayed compared to EiWT. Additionally, triple hemR-immunized fry could mount an immune response and had milder lesions compared to the sham control after EiWT exposure.

Ex vivo biomechanical comparison of four Center of Rotation Angulation Based Leveling Osteotomy fixation methods.

OBJECTIVE: To compare the strength of four constructs used to secure an osteotomy in a Center of Rotation Angulation (CORA)-Based Leveling Osteotomy (CBLO) in an ex vivo model. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Thirty-two canine tibiae from 17 skeletally mature cadavers weighing between 18 and 33.2 kg. METHODS: Thirty-two paired tibiae with patella and patellar tendon were collected. Each tibia was randomly allocated to a construct group: plate and pin (Plate), plate with countersink compression screw (HCS), plate with tension band (TB), or plate with HCS and TB (HCSTB). Samples were loaded by distraction until failure. The stiffness, yield load, and ultimate load were compared between each fixation method. RESULTS: No difference in stiffness of the constructs was detected between groups (p = .6937). Yield load for the HCSTB group (1211.06 N) was greater than the TB group (1016.41 N), the HCS group (907.20 N), and the Plate group (787.73 N) (p = .0069). The ultimate load for the HCSTB group (1387.82 N) was greater than the TB group (1076.36 N), HCS group (926.62 N), and the Plate group (774.35 N) (p = .0004). CONCLUSIONS: CBLO fixation augmented with a TB and HCS provided a stronger construct that withstood a greater yield load and ultimate load than either augmentation strategy alone. CLINICAL SIGNIFICANCE: Augmenting a CBLO fixation with a TB and a HCS can provide increased construct strength.

Effect of washing units of canine red blood cells on storage lesions.

BACKGROUND: In humans, washing stored blood products before transfusion reduces storage lesions and incidence of transfusion reactions, but the effectiveness of washing canine blood is unknown. OBJECTIVES: The objective was to determine if manually washing units of stored blood would reduce storage lesions without adversely affecting erythrocytes. We hypothesized that washing stored units would reduce concentrations of storage lesions and cause minimal erythrocyte damage. ANIMALS: Eight healthy research dogs. METHODS: Repeated measure cohort study. Units of whole blood were stored for 28 days and washed 3 times with 0.9% NaCl. Blood samples were collected before and after storage, after each wash, and after being held at a simulated transfusion temperature. Variables measured included CBC variables, blood gas analysis, erythrocyte morphology, mean corpuscular fragility (MCF), and eicosanoid concentrations. A Friedman's test was used to evaluate changes in variables (P < .05 was considered significant). RESULTS: After the first wash, compared to values after storage, there was a significant decrease in potassium (4.3 mmol/L [4.0-4.7] to 1.2 mmol/L [1-1.6]; P < .0001, median [range]), lactate (1.45 mmol/L [1.07-1.79] to 0.69 mmol/L [0.39-0.93]; P = .002), and partial pressure carbon dioxide (102 mm Hg [80.2-119.2] to 33.7 mm Hg [24.5-44.5]; P < .0001), and increase in MCV (69.3 fL [65.7-72.3] to 74 fL [69.6-79.5]; P = .0003), and MCF (0.444 fL [0.279-0.527] to 0.491 fL [0.43-0.616]; P = .0006). CONCLUSIONS AND CLINICAL IMPORTANCE: A single wash of stored whole blood significantly reduces most extracellular storage lesions, and additional washing might cause hemolysis.

Investigation of fluorescein stain-based tear film breakup time test reliability in dogs in a clinical setting.

OBJECTIVE: To determine intra- and interobserver reliability of a fluorescein stain-based tear film breakup time (TFBUT) test as performed in a clinical environment with and without administration of a topical anesthetic. ANIMALS: 21 privately owned dogs. PROCEDURES: A randomized study design was used. Two independent observers that commonly perform the TFBUT test in clinical practice read the same description of TFBUT. Observers performed TFBUT testing for each dog before and after topical administration of 0.5% proparacaine solution in 4 testing periods with a 1-hour interval between periods. Intraclass correlation coefficient (ICC) analysis was used to assess inter- and intraobserver test reliability. Linear mixed models were used to assess the main effects of testing period, observer, eye, and presence of ophthalmic disorders and their interactions on TFBUT. RESULTS: Mean TFBUT measurements performed by observer 1 and observer 2 were 5.9 seconds and 8.6 seconds, respectively, when adjusted for other effects in the model. Intraobserver ICC was poor for one observer and moderate for the other. Interobserver ICC was poor without use of topical anesthetic and slightly lower when anesthetic was used. Observer and testing period were each significantly associated with TFBUT; the measurements decreased and were more variable after multiple applications of fluorescein stain and proparacaine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested tear film stability is negatively affected by topical administration of 0.5% proparacaine solution and repeated applications of fluorescein stain. The TFBUT test as performed in this study had poor to moderate reliability.

Effects of leukoreduction on N-methylhistamine concentration in stored units of canine whole blood.

OBJECTIVE: To determine the effects of leukoreduction on N-methylhistamine (NMH; a stable histamine metabolite) concentration in units of canine whole blood during storage and incubation at room temperature (approx 22 °C) to simulate temperature conditions during transfusion. ANIMALS: 8 healthy adult Walker Hounds. PROCEDURES: A standard unit of blood (450 mL) was obtained from each dog twice, with at least 28 days between donations. Blood units collected from 4 dogs during the first donation underwent leukoreduction, whereas the blood units collected from the other 4 dogs did not undergo leukoreduction, prior to storage at 4 °C. The alternate treatment was applied to blood units collected during the second donation. A sample from each unit was obtained for determination of plasma NMH concentration the day of donation (before and after leukoreduction when applicable) and before and after incubation at room temperature for 5 hours on days 14 and 28 of storage. RESULTS: Units that underwent leukoreduction had substantially lower leukocyte and platelet counts than nonleukoreduced units. Plasma NMH concentration increased immediately after leukoreduction but did not change significantly during the subsequent 28 days of storage, nor did it differ between units that did and did not undergo leukoreduction. CONCLUSIONS AND CLINICAL RELEVANCE: Leukoreduction and simulated transfusion temperature did not affect the histamine load in units of canine whole blood during the first 28 days of storage. Further research is necessary to determine whether histamine contributes to the development and severity of blood transfusion reactions in dogs.

Effects of pentoxifylline on canine platelet aggregation.

BACKGROUND: Pentoxifylline can decrease platelet function in humans, but the anti-platelet effects of pentoxifylline in dogs is unknown. The addition of a luciferin-luciferase reagent during platelet aggregometry can induce a dose-dependent potentiation of platelet aggregation. OBJECTIVE: To determine if exposure to pentoxifylline, without the addition of a luciferin-luciferase reagent during aggregometry, causes canine platelet dysfunction. Our hypotheses were that pentoxifylline would inhibit platelet function, and that the addition of a luciferin-luciferase reagent would obscure detection of pentoxifylline-induced platelet dysfunction as measured via aggregometry. METHODS: Seven healthy Walker hound dogs. Platelet-rich plasma (PRP) and whole blood were treated for 30 minutes with pentoxifylline: 0 (control), 1 and 2 µg/mL. The platelet aggregation was determined using optical (maximum amplitude) and impedance (ohms) aggregometry using collagen as the agonists, with and without a luciferin-luciferase reagent. Four samples were analysed per concentration and the results were averaged. RESULTS: Based on optical aggregometry, there was no difference (p = 0.964) in the mean maximum amplitude at any pentoxifylline concentration, with and without the luciferin-luciferase reagent. During impedance aggregometry, the addition of a luciferin-luciferase reagent was associated with significantly (p < 0.001) greater platelet aggregation in response to a collagen agonist, regardless of the presence or absence of pentoxifylline. CONCLUSIONS: Pentoxifylline does not exert an in vitro anti-platelet effect on canine platelet aggregation when collagen is used as an agonist, but it is unknown if long-term oral drug administration will inhibit platelet aggregation. The addition of a luciferin-luciferase reagent during platelet aggregometry can artificially enhance canine platelet aggregation.

Pharmacokinetics and pharmacodynamics of intravenous continuous rate infusion and repeated intramuscular administration of dexmedetomidine in standing horses.

An ideal dexmedetomidine protocol has yet to be determined for standing sedation in horses. It was hypothesized that an IV bolus followed by CRI dexmedetomidine would have a quicker increase in plasma concentrations compared with repeated IM injections. In a crossover design, eight adult, female horses were randomly placed into two groups: the CRI group (IV bolus dexmedetomidine at 0.005 mg/kg followed by a CRI at 0.01 mg/kg/h for 15 min then 0.005 mg/kg/h for 60 min) and the IM group (dexmedetomidine at 0.01 mg/kg, followed by 0.005 mg/kg in 30-min intervals for 60 min). Clearance and elimination half-life were 134 ± 67.4 ml/kg/min and 44.3 ± 26.3 min, respectively, in the CRI group, and apparent clearance and half-life were 412 ± 306 ml/kg/min (Cl/F) and 38.9 ± 18.6 min, respectively, in the IM group. Analgesia was evaluated using mechanical pressure threshold. Intravenous dexmedetomidine produced faster onset of sedation and increased pressure threshold compared with IM administration. Individual horses had a large variability in dexmedetomidine plasma concentrations between CRI and IM administration. The odds of a decreased GI motility following IV administration was 12.34 times greater compared with IM administration.

Retrospective Evaluation of Fluoxetine Hydrochloride Use in Horses: 95 Cases (2010-2019).

This study aimed to describe the clinical use of oral fluoxetine hydrochloride administration in horses using a retrospective medical records analysis and to determine owner perception of efficacy via a standardized questionnaire. The records of ninety-five horses for which fluoxetine had been prescribed by the equine service of a veterinary teaching hospital from November 2010 and February 2019 were identified, and data were collected from the medical records. A standardized questionnaire was used to obtain data from owners regarding length of administration, ease of administration, adverse effects, and whether the owner noted improvement in the horse's behavior. Ninety-five horses received fluoxetine during the study period. Fluoxetine was prescribed to facilitate stall rest in 68 horses (Group A) and for behavior-related problems in 27 horses (Group B). The mean dosage was 0.25 mg/kg (range 0.15-0.54). Forty-seven of the 66 owners (71%) that completed the follow-up questionnaire reported a perceived improvement in the animal's behavior (29/41 in Group A and 18/25 in Group B). Fifty-eight owners (88%) reported that they felt the medication was easy to administer. When used to facilitate extended stall confinement, fluoxetine appears to be perceived as efficacious by most owners. Although the number of behavioral cases was low, the results indicate that the drug may also be useful for some problem behaviors. Further controlled behavioral studies are needed to investigate the use of fluoxetine for equine behavioral problems.

Biomechanical Comparison of External Fixation and Double Plating for Stabilization of a Canine Cadaveric Supracondylar Humeral Fracture Gap Model.

OBJECTIVE: Successful stabilization of comminuted supracondylar humeral fractures is challenging, and biomechanical studies are scarce. This study compares double-plate (DB-PLATE) and linear external fixator with an intramedullary pin tie-in (ESF-IMP) fixation techniques in a cadaveric gap model. The hypothesis was the DB-PLATE construct would be stiffer, stronger and more resistant to repeated loading than the ESF-IMP construct in both cyclic and load-to-failure axial compression testing. STUDY DESIGN: A 2 cm ostectomy was performed on 10 pairs of canine cadaveric humeri proximal to the supratrochlear foramen. Stabilization was with DB-PLATE (n = 10) or ESF-IMP (n = 10). Cyclic testing was performed by applying a 200 N load at 2 Hz for 63,000 cycles. Axial compressive load to failure testing followed. Data analysed included dynamic stiffness, stiffness and yield load. RESULTS: No constructs failed during cyclic testing or lost stiffness over time. Mean dynamic stiffness over the final 100 cycles was greater for DB-PLATE compared with ESF-IMP. Mean stiffness of DB-PLATE in load-to-failure testing was not different than ESF-IMP. Yield load of DB-PLATE was higher than ESF-IMP. CONCLUSION: Both DB-PLATE and ESF-IMP survived cyclic testing with no change in dynamic stiffness. DB-PLATE was stronger than ESF-IMP in load-to-failure testing, which may make this construct preferable when prolonged healing or poor patient compliance is anticipated. Results suggest that either method may be appropriate for fixation of comminuted supracondylar humeral fractures.

A system dynamics model for disease management in poultry production.

The objective of this article was to provide the nonmodeler reader of Poultry Science, an overview of the system dynamics modeling method (SDM) through development of a broiler house disease management simulator (BHDMS). System dynamics modeling uses feedback theory and computer-aided simulation to help elucidate relationships between factors in complex systems, which may be circular or interrupted with long delays. Materials used to build the simulator include data from literature and industry indices. The methods used were the steps in SDM, namely: 1) Identify the problem and boundaries; 2) develop a dynamic hypothesis explaining cause of the problem; 3) build the causal loop diagram (CLD); 4) develop the stock and flow model; 5) conduct model simulations; and 6) model validation. Results presented here are the CLD and stock and flow model of the simulator, results of scenario simulations, and model validity tests. The simulator consists of the main model, the disease submodel, and the antimicrobial use submodel. The main model represents a cycle of production in the broiler house of a specified length of time, which repeats after a specified down time. The disease submodel shows population dynamics in the broiler house in terms of changes over time in number of susceptible, infected, recovered, and dead birds. Production parameters that could be modified in the model include delivery size, grow-out period, down time, and efficacy of antimicrobials. Disease mortality levels, above the set threshold, trigger antimicrobial use in the model. The model showed the effect of antimicrobial use intervention on the population dynamics, namely, on the proportion of the susceptible, infected, recovered, and dead birds in the population. Thus, the BHDMS was able to simulate the effect of the intervention on population dynamics and would facilitate evaluating management interventions such as antimicrobial use.