Objective—To characterize the impact of Mannheimia haemolytica infection on feed intake and weight gain in feedlot heifers and to evaluate the clinical efficacy of isoflupredone acetate administered in combination with oxytetracycline. Animals—96 weanling heifers in a research feedlot facility. Procedures—Bronchopneumonia was induced by intrabronchial infusion of M haemolytica. Control heifers underwent a sham procedure. Infected heifers were treated with oxytetracycline alone or in combination with isoflupredone acetate (OXY-ISO) or with nothing. Clinical variables were recorded daily for 7 days following disease induction, and feedlot performance indices were measured over a 12-week period. Results—Infection caused a reduction in dry-matter intake and average daily gain (ADG) in heifers that received no treatment. Oxytetracycline treatment alone did not prevent reductions in feed intake and ADG during the first week after infection was induced, whereas OXY-ISO treatment did prevent these reductions. Treatment with OXY-ISO also resulted in faster clinical improvement. No significant differences were evident between the oxytetracycline and OXY-ISO groups with respect to dry-matter intake or ADG throughout the study period. Conclusions and Clinical Relevance—Isoflupredone acetate appeared to be a useful clinical adjunct to treatment with oxytetracycline in cattle with acute M haemolytica bronchopneumonia.

Objective—To characterize the electroencephalogram (EEG) in young cats. Animals—23 clinically normal cats. Procedures—Cats were sedated with medetomidine hydrochloride and butorphanol tartrate at 2, 4, 6, 8, 12, 16, 20, and 24 weeks of age, and an EEG was recorded at each time point. Recordings were visually inspected for electrical continuity, interhemispheric synchrony, amplitude and frequency of background electrical activity, and frequency of transient activity. Computer-aided analysis was used to perform frequency spectral analysis and to calculate absolute and relative power of the background activity at each age. Results—Electrical continuity was evident in cats ≥ 4 weeks old, and interhemispheric synchrony was evident in cats at all ages evaluated. Analysis of amplitude of background activity and absolute power revealed significant elevations in 6-week-old cats, compared with results for 2-, 20-, and 24-week-old cats. No association between age and relative power or frequency was identified. Transient activity, which consisted of sleep spindles and K complexes, was evident at all ages, but spike and spike-and-wave discharges were observed in cats at 2 weeks of age. Conclusions and Clinical Relevance—Medetomidine and butorphanol were administered in accordance with a sedation protocol that allowed investigators to repeatedly obtain EEG data from cats. Age was an important consideration when interpreting EEG data. These data on EEG development in clinically normal cats may be used for comparison in future studies conducted to examine EEGs in young cats with diseases that affect the cerebral cortex.

Objective—To determine antimicrobial effects of caprylic acid and its derivatives, monocaprylin and sodium caprylate, on Dermatophilus congolensis and to determine effects of caprylic acid on the ultrastructure of D congolensis by use of transmission electron microscopy (TEM). Sample—3 strains of D congolensis (33411, 33413, and 14639). Procedures—Strains of D congolensis were incubated separately under anaerobic conditions at 37°C for up to 48 hours in brain heart infusion (BHI) broth that was supplemented with various concentrations of caprylic acid (7.5, 12.5, 15, 17.5, or 20mM), monocaprylin (2.5, 5, 7.5, or 10mM), or sodium caprylate (15, 50, 60, 70, 100, or 120mM) or contained no antimicrobial treatment. After incubation, bacterial counts were determined by means of plating in triplicate on BHI-agar plates. Caprylic acid-treated or untreated D congolensis samples were embedded in epoxide resin for TEM; cross sections were examined for structural damage. Results—Minimum inhibitory concentrations of caprylic acid, monocaprylin, and sodium caprylate against D congolensis were 7.5, 2.5, and 15mM, respectively. Minimum bactericidal concentrations of caprylic acid, monocaprylin, and sodium caprylate against D congolensis were 15, 5, and 70mM, respectively. Examination via TEM revealed that a 15-mM concentration of caprylic acid disintegrated the plasma membrane of D congolensis. Conclusions and Clinical Relevance—Results indicated that caprylic acid, monocaprylin, and sodium caprylate could potentially be used to treat D congolensis infections. However, in vivo studies should be undertaken to determine whether these compounds can be considered as treatment options.

Objective: To determine associations between serum concentrations of omega-3 polyunsaturated fatty acids and concentrations of adiponectin, leptin, and insulin in healthy cats. Animals: 56 healthy adult client-owned cats. Procedures: Body condition score (BCS) was determined, and blood samples were collected after food was withheld for 12 hours. Serum was harvested for fatty acid analysis and measurement of serum concentrations of adiponectin, leptin, insulin, glucose, triglyceride, and cholesterol. Results: 1 cat was removed because of hyperglycemia. Significant interaction effects between BCS and serum concentrations of eicosapentaenoic acid (EPA) were detected for the analyses of associations between EPA and serum concentrations of adiponectin, insulin, and triglyceride. Cats were categorized into nonobese (BCS, 4 to 6 [n = 34 cats]) and obese (BCS, 7 to 8 [21]) groups; serum concentrations of EPA were directly associated with concentrations of adiponectin and inversely associated with concentrations of insulin and triglyceride in obese cats and were directly associated with concentrations of leptin and inversely associated with concentrations of adiponectin in nonobese cats. Additionally, serum concentrations of docosahexaenoic acid were directly associated with concentrations of adiponectin in obese cats. No significant associations between serum concentrations of docosahexaenoic acid or α-linolenic acid were detected in the analyses for all cats. Female cats had higher serum concentrations of adiponectin and lower concentrations of glucose than did male cats. Increased age was associated with a small increase in serum concentrations of leptin. Conclusions and Clinical Relevance: EPA may ameliorate the decrease in adiponectin and the increase in insulin and triglyceride concentrations in obese cats.

Objective—To evaluate the effect of administration of the labeled dosage of pimobendan to dogs with furosemide-induced activation of the renin-angiotensin-aldosterone system (RAAS). Animals—12 healthy hound-type dogs. Procedures—Dogs were allocated into 2 groups (6 dogs/group). One group received furosemide (2 mg/kg, PO, q 12 h) for 10 days (days 1 to 10). The second group received a combination of furosemide (2 mg/kg, PO, q 12 h) and pimobendan (0.25 mg/kg, PO, q 12 h) for 10 days (days 1 to 10). To determine the effect of the medications on the RAAS, 2 urine samples/d were obtained for determination of the urinary aldosterone-to-creatinine ratio (A:C) on days 0 (baseline), 5, and 10. Results—Mean ± SD urinary A:C increased significantly after administration of furosemide (baseline, 0.37 ± 0.14 µg/g; day 5, 0.89 ± 0.23 µg/g) or the combination of furosemide and pimobendan (baseline, 0.36 ± 0.22 µg/g; day 5, 0.88 ± 0.55 µg/g). Mean urinary A:C on day 10 was 0.95 ± 0.63 µg/g for furosemide alone and 0.85 ± 0.21 µg/g for the combination of furosemide and pimobendan. Conclusions and Clinical Relevance—Furosemide-induced RAAS activation appeared to plateau by day 5. Administration of pimobendan at a standard dosage did not enhance or suppress furosemide-induced RAAS activation. These results in clinically normal dogs suggested that furosemide, administered with or without pimobendan, should be accompanied by RAAS-suppressive treatment

Objective—To assess the suitability of the modified acetaminophen absorption test for evaluation of abomasal emptying rate in ruminating cattle. Animals—7 Holstein-Friesian heifers. Procedures—In a crossover study design, heifers consecutively underwent an IV infusion of 1 L of saline (0.9% NaCl) solution (control treatment), 1 L of saline solution containing metoclopramide (0.1 mg/kg), and 1 L of saline solution containing atropine (0.1 mg/kg), with an interval of 15 days between treatments. Immediately after each treatment, acetaminophen diluted in ethanol (50 mg/kg) was infused transcutaneously into the abomasum. Blood samples were obtained repeatedly for measurement of plasma acetaminophen concentration, and pharmacokinetic data were obtained. Results—Maximum plasma acetaminophen concentration was significantly lower after atropine treatment than after control or metoclopramide treatment, whereas no difference was identified between control and metoclopramide treatments. The interval to maximum plasma acetaminophen concentration was significantly longer in atropine-treated versus metoclopramide-treated heifers. The interval to maximum acetaminophen concentration obtained from a pharmacokinetic model was significantly longer for atropine than for control and metoclopramide treatment. Similarly, areas under the plasma acetaminophen concentration-time curves for the first 60, 90, 120, and 240 minutes after administration were significantly lower for atropine versus metoclopramide or control treatment, whereas differences between metoclopramide and control treatments were not identified. Conclusions and Clinical Relevance—The modified acetaminophen absorption test was a practical, minimally invasive, and reliable method to assess abomasal emptying in cattle. Metoclopramide administered at a dose of 0.1 mg/kg did not increase the abomasal emptying rate.

A fast, sensitive, and specific reverse-transcription (RT) loop-mediated isothermal amplification (RT-LAMP) assay was developed that involved a single tube and a 1-step reaction for detecting infectious bursal disease virus (IBDV). Four specific primers were used for amplification of the VP2 gene of IBDV. The amplified LAMP products were detected by DNA electrophoresis and by direct observation with the naked eye in the presence of SYBR Green I. The sensitivity of RT-LAMP was determined to be 0.01 fg of IBDV viral RNA. This assay for IBDV is more sensitive than the conventional RT-polymerase chain reaction assay, which has a detection limit of 1 ng. The LAMP assay was also assessed for specificity and was found to precisely discriminate between positive and negative test samples. This newly established LAMP assay, combined with RT, is a practical diagnostic tool because IBDV-infected and uninfected clinical samples collected from an experimental farm could be discriminated. Full verification of a sample’s IBDV status was obtained within 40 min of extraction of the viral RNA, which could then be directly added to the RT-LAMP reaction mixture.

Objective: To evaluate influence of electrode position on cardioversion energy (CE; energy delivered in the shock at which cardioversion was achieved) during transvenous electrical cardioversion (TVEC) in horses with atrial fibrillation. Animals: 37 horses with atrial fibrillation (41 cardioversion events). Procedures: Records were reviewed to identify horses that underwent TVEC for treatment of atrial fibrillation. Signalment and CE were recorded. Electrode positions in the right atrium and pulmonary artery were identified on intraoperative radiographs. An orthogonal coordinate space was created, and electrode y- and z-axis coordinates and shadow lengths were determined. Trigonometric modeling was used to estimate x-axis electrode positions that resulted in observed shadows. Postmortem casts of catheterized horses were used to assess electrode paths and anatomic relationships. Model assumptions were tested by use of these and a theoretical data set. Relationships between signalment, electrode position, and CE were assessed via multivariate analysis. Results: Sex and y-axis differences between electrode positions were significant predictors of CE. Population stratification based on examination of residuals improved model strength; populations differed in z-axis variables and in CE. Decreasing distance between electrodes and pulmonary artery electrode positions ventral to the right atrium were associated with increased CE. Agreement between estimated and actual x-axis coordinates was poor. Conclusions and Clinical Relevance: Optimal electrode positioning can reduce the energy requirement for successful TVEC and may eventually support application of TVEC under short-term IV anesthesia and potentially increase chances of treatment response. Further investigation into these relationships is warranted.

Objective—To develop and determine the feasibility of a novel minimally invasive technique for percutaneous catheterization and embolization of the thoracic duct (PCETD) in dogs and to determine thoricic duct TD pressure at rest and during short-term balloon occlusion of the cranial vena cava (CrVC). Animals—Fifteen 7- to 11-month-old healthy mixed-breed dogs. Procedures—Efferent intestinal lymphangiography was performed, and the cisterna chyli was punctured with a trochar needle percutaneously under fluoroscopic guidance. When access was successful, a guide wire was directed into the TD through the needle and a vascular access sheath was advanced over the guide wire. Thoracic duct pressure was measured at rest and during acute balloon occlusion of the CrVC. The TD was then embolized cranial to the diaphragm with a combination of microcoils and cyanoacrylate or ethylene vinyl alcohol. Results—Successful puncture of the cisterna chyli with advancement of a wire into the TD was possible in 9 of 15 dogs, but successful catheterization was possible in only 5 of 9 dogs. Acute balloon occlusion of the CrVC led to a substantial TD pressure increase in 4 of 4 dogs, and embolization of the TD was successful in 4 of 4 dogs. Conclusions and Clinical Relevance—PCETD can successfully be performed in healthy dogs; however, this minimally invasive technique cannot currently be recommended for routine treatment of chylothorax, in part because of the technically demanding nature of the procedure. An increase in jugular venous pressure led to an increase in TD pressure, potentially predisposing some dogs to developing chylothorax.

Objective—To determine expression of cyclooxygenase (COX) genes 1 and 2 (also called prostaglandin-endoperoxide synthases 1 and 2) and stability of housekeeping gene expression during low-flow ischemia and reperfusion in the jejunum of horses. Animals—5 healthy adult horses. Procedures—Horses were anesthetized, and two 30-cm segments of jejunum were surgically exteriorized. Blood flow was maintained at baseline (untreated) values in 1 (control) segment and was decreased to 20% of baseline (low-flow ischemia) for 75 minutes, followed by 75 minutes of reperfusion, in the other (experimental) segment. Biopsy samples were collected from experimental segments at baseline (T0), after 75 minutes of ischemia (T1), and after 75 minutes of reperfusion (T2); samples were collected from control segments at T0 and T2. Horses were euthanized 24 hours after induction of ischemia (T3), and additional samples were collected. Samples were evaluated histologically. Total RNA was extracted; expression of COX genes and stability of 8 housekeeping genes were determined via quantitative real-time PCR assays. Results—COX-1 and COX-2 genes were constitutively expressed in baseline samples. Low-flow ischemia resulted in significant upregulation of COX-2 gene expression at each subsequent time point, compared with baseline values. The most stably expressed reference genes were β-actin and hypoxanthine phosphoribosyltransferase, whereas glyceraldehyde 3-phosphate dehydrogenase and β-2 microglobulin were the least stably expressed. Conclusions and Clinical Relevance—Low-flow ischemia resulted in upregulation of COX-2 gene expression in the jejunum of horses. Housekeeping genes traditionally used as internal standards may not be stable in this tissue during arterial low-flow ischemia and reperfusion.