Objective—To assess biometric tools for gait analysis in healthy calves by use of pressure mat sensors, a handheld algometer, and serial circumferential measurements of selected joints. Animals—20 six- to eight-week-old healthy male Holstein calves. Procedures—Calves were evaluated over a 4-day period. Gait analysis was performed by training calves to walk over a pressure-sensitive mat, which recorded quantitative measurements. An algometer was applied perpendicular to each joint until an aversion response was observed or a preset limit of 50 N/cm2 was obtained. Circumference measurements of the carpal and tarsal joints were obtained by the application of a flexible measuring tape to defined areas of each limb. Variability between joint circumference measurements and pressure mat variables were analyzed with a standard least squares means model. Algometer measurements were dichotomized, and logistic regression was used to assess the probability that a calf reacted to algometer-applied pressure. Results—1 calf was removed from the study because of lameness. Mean carpal and tarsal joint circumference measurements were reliable and consistent among calves. Algometry results suggested that healthy calves were more sensitive to pressure applied to the elbow and stifle joints, compared with pressure applied to the carpal, tarsal, and metacarpophalangeal or metatarsophalangeal joints. Pressure mat variables of stance time and stride velocity varied greatly among calves, whereas impulse and maximum forces varied little. Conclusions and Clinical Relevance—Findings can serve as reference points for other studies and be used for comparison with results for calves with lameness or altered gaits.

Objective-To determine the pharmacokinetics of tramadol hydrochloride (30 mg/kg) following twice-daily oral administration in Hispaniolan Amazon parrots (Amazona ventralis). Animals-9 healthy adult Hispaniolan Amazon parrots. Procedures-Tramadol hydrochloride was administered to each parrot at a dosage of 30 mg/kg, PO, every 12 hours for 5 days. Blood samples were collected just prior to dose 2 on the first day of administration (day 1) and 5 minutes before and 10, 20, 30, 60, 90, 180, 360, and 720 minutes after the morning dose was given on day 5. Plasma was harvested from blood samples and analyzed by high-performance liquid chromatography. Degree of sedation was evaluated in each parrot throughout the study. Results-No changes in the parrots’ behavior were observed. Twelve hours after the first dose was administered, mean +/- SD concentrations of tramadol and its only active metabolite M1 (O-desmethyltramadol) were 53 +/- 57 ng/mL and 6 +/- 6 ng/mL, respectively. At steady state following 4.5 days of twice-daily administration, the mean half-lives for plasma tramadol and M1 concentrations were 2.92 +/- 0.78 hours and 2.14 +/- 0.07 hours, respectively. On day 5 of tramadol administration, plasma concentrations remained in the therapeutic range for approximately 6 hours. Other tramadol metabolites (M2, M4, and M5) were also present. Conclusions and Clinical Relevance-On the basis of these results and modeling of the data, tramadol at a dosage of 30 mg/kg, PO, will likely need to be administered every 6 to 8 hours to maintain therapeutic plasma concentrations in Hispaniolan Amazon parrots.

Objective-To test the hypothesis that inflammatory responses to endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Animals-6 healthy horses and 6 horses with EMS. Procedures-Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline data were obtained 30 minutes before each infusion. After infusion, a physical examination was performed hourly for 9 hours and at 15 and 21 hours; a whole blood sample was collected at 30, 60, 90, 120, 180, and 240 minutes for assessment of inflammatory cytokine gene expression. Liver biopsy was performed between 240 and 360 minutes after infusion. Results-Following lipopolysaccharide infusion in healthy horses and horses with EMS, mean rectal temperature, heart rate, and respiratory rate increased, compared with baseline findings, as did whole blood gene expression of interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor-α. The magnitude of blood cytokine responses did not differ between groups, but increased expression of IL-6, IL-8, IL-10, and tumor necrosis factor-α persisted for longer periods in EMS-affected horses. Lipopolysaccharide infusion increased liver tissue gene expressions of IL-6 in healthy horses and IL-8 in both healthy and EMS-affected horses, but these gene expressions did not differ between groups. Conclusions and Clinical Relevance-Results supported the hypothesis that EMS affects horses’ inflammatory responses to endotoxin by prolonging cytokine expression in circulating leukocytes. These findings are relevant to the association between obesity and laminitis in horses with EMS.

Objective-To test the hypothesis that glucose and insulin dynamics during endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Animals-6 healthy adult mares and 6 horses with EMS. Procedures-Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline insulin-modified frequently sampled IV glucose tolerance tests were performed 27 hours before and then repeated at 0.5 and 21 hours after infusion. Results were assessed via minimal model analysis and area under the curve values for plasma glucose and serum insulin concentrations. Results-Lipopolysaccharide infusion decreased insulin sensitivity and increased area under the serum insulin concentration curve (treatment × time) in both healthy and EMS-affected horses, compared with findings following saline solution administration. The magnitude of increase in area under the plasma glucose curve following LPS administration was greater for the EMS-affected horses than it was for the healthy horses. Horses with EMS that received LPS or saline solution infusions had decreased insulin sensitivity over time. Conclusions and Clinical Relevance-Glucose and insulin responses to endotoxemia differed between healthy horses and horses with EMS, with greater loss of glycemic control in EMS-affected horses. Horses with EMS also had greater derangements in glucose and insulin homeostasis that were potentially stress induced. It may therefore be helpful to avoid exposure of these horses to stressful situations.

The aim of this study was to determine the efficacy of a concentrated combination of tiletamine-zolazepam [TZ, 0.53 mg/kg body weight (BW)], ketamine (Ket, 0.53 mg/kg BW), and detomidine (Det, 0.04 mg/kg BW) in the immobilization of free-range cattle for clinical procedures. The combination was administered intramuscularly to 53 animals. Anesthesia was reversed with the α2-adrenoceptor antagonist atipamezole. Locoregional anesthesia was provided with lidocaine when required. The TZKD combination induced suitable immobilization for minor surgical procedures or medical treatments. Anesthetic onset was rapid, taking a mean of 6.1 min [standard deviation (SD) 2.8 min]. The duration of anesthesia depended on the time of administration of the antagonist; the animals recovered in the standing position in 12.9 ± 8.9 min after the administration of atipamezole. The quality of anesthesia and analgesia were satisfactory. In conclusion, this TZKD combination can be used for both immobilization and minor surgical procedures in free-range cattle.

Objective-To compare effects of anesthetic induction with midazolam-propofol or midazolam-etomidate on intraocular pressure (IOP), pupillary diameter (PD), pulse rate, blood pressure, and respiratory rate in clinically normal dogs. Animals-18 dogs. Procedures-Dogs undergoing ophthalmic surgery received midazolam (0.2 mg/kg, IV) and either propofol or etomidate (IV) until intubatable. For all dogs, results of physical examinations, ophthalmic examinations of the nonoperated eye, and preanesthetic blood analyses were normal. Intraocular pressure, PD, blood pressure, pulse rate, and respiratory rate were measured in the nonoperated eye at 5 time points: just prior to the anesthetic induction sequence, after 5 minutes of preanesthetic oxygenation via face mask, after IV administration of midazolam, after IV anesthetic induction, and after endotracheal intubation. Results-PD decreased significantly from baseline by 4.4 +/- 0.4 mm (mean +/- SD) after anesthetic induction and 5.3 +/- 0.4 mm after intubation in the etomidate group and by 1. 2 +/- 0.4 mm after intubation in the propofol group. Intraocular pressure was increased significantly from baseline by 3.2 +/- 1.0 mm Hg after anesthetic induction in the etomidate group and by 4.7 +/- 1.2 mm Hg after anesthetic induction and 4.5 +/- 1. 2 mm Hg after intubation in the propofol group. Pulse rate was significantly lower by 28.6 +/- 12.6 beats/min after anesthetic induction in the etomidate group, compared with the propofol group. Conclusions and Clinical Relevance-At the studied doses, midazolam-etomidate caused clinically important miosis and increased IOP. Midazolam-propofol caused an even greater increase in IOP but had minimal effects on PD.

Objective-To characterize systemic immune responses in Cytauxzoon felis-infected cats. Sample-Blood and lung samples obtained from 27 cats. Procedures-Cats were allocated into 4 groups: cats that died of cytauxzoonosis, acutely ill C felis-infected cats, healthy survivors of C felis infection, and healthy uninfected cats. Serum concentrations of tumor necrosis factor-α and interleukin-1 β were measured and serum proteins characterized. Blood smears were stained immunocytochemically and used to assess immunoglobulin deposition. Immunohistochemical expression of CD18 and tumor necrosis factor-α were compared in lung tissues obtained from cats that died and healthy uninfected cats. A real-time reverse-transcription PCR assay for CD18 expression was performed on selected blood samples from all groups. Results-Concentrations of both cytokines were greater and serum albumin concentrations were significantly lower in cats that died of cytauxzoonosis, compared with results for all other groups. Erythrocytes from acutely ill cats and survivors of C felis infection had staining for plasmalemmal IgM, whereas erythrocytes from the other groups did not. Increased staining of C felis-infected monocytes and interstitial neutrophils for CD18 was detected. The real-time reverse-transcription PCR assay confirmed a relative increase in CD18 expression in cats that died of cytauxzoonosis and acutely ill cats, compared with expression in other groups. Immunostaining for TNF-α in lung samples confirmed a local proinflammatory response. Conclusions and Clinical Relevance-Results indicated immunopathologic responses were greater in cats that died of C felis infection than in cats that survived C felis infection.

Objective-To use noninvasive respiratory inductance plethysmography (RIP) to investigate differences in breathing patterns between horses with and without recurrent airway obstruction (RAO) during the onset of airway obstruction induced through confinement to stables. Animals-12 horses with no history or clinical signs of respiratory disease (control horses) and 7 RAO-affected horses. Procedures-The study involved 2 phases. In phase 1, the optimal position of RIP bands for recording pulmonary function was investigated in 12 control horses. In phase 2, 7 RAO-affected and 7 control horses were confined to stables. Respiratory inductance plethysmography bands were applied to horses for 24 h/d to record respiratory rate and total displacement in 4-hour periods for 7 days or until RAO-affected horses developed signs of severe RAO that persisted for 2 consecutive days. Lung function was measured once daily. Results-In phase 1, thoracic and abdominal cavity displacements were best represented by RIP bands positioned at intercostal spaces 6 and 17, respectively. In phase 2, pulmonary function indicated airway obstruction in the RAO-affected group on the final 2 days of stable confinement. Respiratory rate and total degree of respiratory displacement measured by RIP did not differ between the RAO-affected and control groups, but the SDs of these decreased significantly within 8 hours after stable confinement began in RAO-affected horses. Respiratory inductance plethysmography and pulmonary function findings became highly correlated as severity of disease progressed. Conclusions and Clinical Relevance-The decrease in the SDs of RIP measurements indicated a lower degree of variability in breathing patterns of RAO-affected horses. This loss of variability may provide an early indicator of airway inflammation.

Bovine viral diarrhea virus (BVDV) is a widespread bovine pathogen capable of causing disease affecting multiple body systems. Previous studies have shown 2-(2-benzimidazolyl)-5-[4-(2-imidazolino)phenyl]furan dihydrochloride (DB772) effectively prevents BVDV infection in cell culture. The aim of this project was to assess the efficacy of DB772 for the prevention of acute BVDV infection. Four calves seronegative to BVDV were treated with DB772 and another 4 calves were treated with diluent only on the same dosing schedule. Each calf was subsequently challenged intranasally with BVDV. Virus was isolated consistently from untreated calves on days 4 to 8, while treated calves remained negative by virus isolation during this period. Azotemia was exhibited by all treated calves on day 4 resulting in the euthanasia of 1 calf on day 10 and the death of another on day 13. Virus was isolated from the 2 remaining treated calves on day 14 or 21. On day 21, both remaining treated calves and all 4 untreated calves had anti-BVDV antibody titers > 1:2048. This pilot study indicates that DB772 temporarily prevented acute disease due to BVDV, but carries a significant concern of renal toxicity.

Objective-To assess antimicrobial resistance and transfer of virulence genes facilitated by subtherapeutic concentrations of antimicrobials in swine intestines. Animals-20 anesthetized pigs experimentally inoculated with donor and recipient bacteria. Procedures-4 recipient pathogenic bacteria (Salmonella enterica serotype Typhimurium, Yersinia enterocolitica, Shigella flexneri, or Proteus mirabilis) were incubated with donor bacteria in the presence of subinhibitory concentrations of 1 of 16 antimicrobials in isolated ligated intestinal loops in swine. Donor Escherichia coli contained transferrable antimicrobial resistance or virulence genes. After coincubations, intestinal contents were removed and assessed for pathogens that acquired new antimicrobial resistance or virulence genes following exposure to the subtherapeutic concentrations of antimicrobials. Results-3 antimicrobials (apramycin, lincomycin, and neomycin) enhanced transfer of an antimicrobial resistance plasmid from commensal E coli organisms to Yersinia and Proteus organisms, whereas 7 antimicrobials (florfenicol, hygromycin, penicillin G, roxarsone, sulfamethazine, tetracycline, and tylosin) exacerbated transfer of an integron (Salmonella genomic island 1) from Salmonella organisms to Yersinia organisms. Sulfamethazine induced the transfer of Salmonella pathogenicity island 1 from pathogenic to nonpathogenic Salmonella organisms. Six antimicrobials (bacitracin, carbadox, erythromycin, sulfathiazole, tiamulin, and virginiamycin) did not mediate any transfer events. Sulfamethazine was the only antimicrobial implicated in 2 types of transfer events. Conclusions and Clinical Relevance-10 of 16 antimicrobials at subinhibitory or subtherapeutic concentrations augmented specific antimicrobial resistance or transfer of virulence genes into pathogenic bacteria in isolated intestinal loops in swine. Use of subtherapeutic antimicrobials in animal feed may be associated with unwanted collateral effects.