OBJECTIVE To determine the pharmacokinetics of meloxicam in domestic hens and duration and quantity of drug residues in their eggs following PO administration of a single dose (1 mg of meloxicam/kg). ANIMALS 8 healthy adult White Leghorn hens. PROCEDURES Hens were administered 1 mg of meloxicam/kg PO once. A blood sample was collected immediately before and at intervals up to 48 hours after drug administration. The hens' eggs were collected for 3 weeks after drug administration. Samples of the hens' plasma, egg whites (albumen), and egg yolks were analyzed by high-performance liquid chromatography. RESULTS The half-life, maximum concentration, and time to maximum concentration of meloxicam in plasma samples were 2.8 hours, 7.21 μg/mL, and 2 hours, respectively. Following meloxicam administration, the drug was not detected after 4 days in egg whites and after 8 days in egg yolks. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that meloxicam administered at a dose of 1 mg/kg PO in chickens appears to maintain plasma concentrations equivalent to those reported to be therapeutic for humans for 12 hours. The egg residue data may be used to aid establishment of appropriate drug withdrawal time recommendations.

OBJECTIVE To characterize clinical findings for polysaccharide storage myopathy (PSSM) in warmblood horses with type 1 PSSM (PSSM1; caused by mutation of the glycogen synthase 1 gene) and type 2 PSSM (PSSM2; unknown etiology). SAMPLE Database with 3,615 clinical muscle biopsy submissions. PROCEDURES Reported clinical signs and serum creatine kinase (CK) and aspartate aminotransferase (AST) activities were retrospectively analyzed for horses with PSSM1 (16 warmblood and 430 nonwarmblood), horses with PSSM2 (188 warmblood and 646 nonwarmblood), and warmblood horses without PSSM (278). Lameness examinations were reviewed for 9 warmblood horses with PSSM2. Muscle glycogen concentrations were evaluated for horses with PSSM1 (14 warmblood and 6 nonwarmblood), warmblood horses with PSSM2 (13), and horses without PSSM (10 warmblood and 6 nonwarmblood). RESULTS Rhabdomyolysis was more common for horses with PSSM1 (12/16 [75%] warmblood and 223/303 [74%] nonwarmblood) and nonwarmblood horses with PSSM2 (221/436 [51%]) than for warmblood horses with PSSM2 (39/147 [27%]). Gait abnormality was more common in warmblood horses with PSSM2 (97/147 [66%]) than in warmblood horses with PSSM1 (1/16 [7%]), nonwarmblood horses with PSSM2 (176/436 [40%]), and warmblood horses without PSSM (106/200 [53%]). Activities of CK and AST were similar in warmblood horses with and without PSSM2. Muscle glycogen concentrations in warmblood and nonwarmblood horses with PSSM1 were significantly higher than concentrations in warmblood horses with PSSM2. CONCLUSIONS AND CLINICIAL RELEVANCE Rhabdomyolysis and elevated muscle glycogen concentration were detected in horses with PSSM1 regardless of breed. Most warmblood horses with PSSM2 had stiffness and gait abnormalities with CK and AST activities and muscle glycogen concentrations within reference limits.

OBJECTIVE To determine pharmacokinetics and pulmonary disposition of minocycline in horses after IV and intragastric administration. ANIMALS 7 healthy adult horses. PROCEDURES For experiment 1 of the study, minocycline was administered IV (2.2 mg/kg) or intragastrically (4 mg/kg) to 6 horses by use of a randomized crossover design. Plasma samples were obtained before and 16 times within 36 hours after minocycline administration. Bronchoalveolar lavage (BAL) was performed 4 times within 24 hours after minocycline administration for collection of pulmonary epithelial lining fluid (PELF) and BAL cells. For experiment 2, minocycline was administered intragastrically (4 mg/kg, q 12 h, for 5 doses) to 6 horses. Plasma samples were obtained before and 20 times within 96 hours after minocycline administration. A BAL was performed 6 times within 72 hours after minocycline administration for collection of PELF samples and BAL cells. RESULTS Mean bioavailability of minocycline was 48% (range, 35% to 75%). At steady state, mean ± SD maximum concentration (Cmax) of minocycline in plasma was 2.3 ± 1.3 μg/mL, and terminal half-life was 11.8 ± 0.5 hours. Median time to Cmax (Tmax) was 1.3 hours (interquartile range [IQR], 1.0 to 1.5 hours). The Cmax and Tmax of minocycline in the PELF were 10.5 ± 12.8 μg/mL and 9.0 hours (IQR, 5.5 to 12.0 hours), respectively. The Cmax and Tmax for BAL cells were 0.24 ± 0.1 μg/mL and 6.0 hours (IQR, 0 to 6.0 hours), respectively. CONCLUSIONS AND CLINICAL RELEVANCE Minocycline was distributed into the PELF and BAL cells of adult horses.

OBJECTIVE: To investigate the distribution of T-cell markers (CD4 and CD8α) in lymphoid organs of newborn, juvenile, and adult yaks. ANIMALS: 15 healthy male yaks of various ages from highland plateaus. PROCEDURES: Yaks were allocated to groups on the basis of age (newborn [1 to 7 days old; n = 5], juvenile [5 to 7 months old; 5], and adult [3 to 4 years old; 5]). The thymus, spleen, 5 mesenteric lymph nodes, and 5 hemal nodes were harvested from each yak within 10 minutes after euthanasia. Morphological characteristics of those lymphoid organs were assessed by histologic examination; expression of CD4 and CD8α mRNAs and proteins were measured by quantitative real-time PCR assay and immunohistochemical staining. RESULTS: Among the lymphoid organs evaluated, expressions of CD4 and CD8α mRNAs were highest in the thymus in all age groups. In newborn lymphoid organs, CD4 mRNA expression and CD4+ cell distribution were more predominant, whereas in juvenile and adult lymphoid organs, CD8α mRNA expression and CD8α+ cell distribution were more predominant. The CD4+ and CD8α+ cells were mainly located in the cortex and medulla of the thymus, the medulla of the hemal nodes and mesenteric lymph nodes, the periarteriolar lymphoid sheaths, and the red pulp of the spleen. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the CD4 mRNA expression and CD4+ T-cell distribution in yak lymphoid organs decreased and CD8α mRNA expression and CD8α+ T-cell distribution increased with age. Moreover, CD8α+ cells were present in the follicles of yaks’ secondary lymphoid organs, which differs from findings for other mammals.

OBJECTIVE To determine effects of fentanyl, lidocaine, and a fentanyl-lidocaine combination on the minimum alveolar concentration of sevoflurane preventing motor movement (MACNM) in dogs. ANIMALS 6 adult Beagles. PROCEDURES Dogs were anesthetized with sevoflurane in oxygen 3 times (1-week intervals). Baseline MACNM (MAC(NM-B)) was determined starting 45 minutes after induction of anesthesia. Dogs then received 1 of 3 treatments IV: fentanyl (loading dose, 15 μg/kg; constant rate infusion [CRI], 6 μg/kg/h), lidocaine (loading dose, 2 mg/kg; CRI, 6 mg/kg/h), and the fentanyl-lidocaine combination at the same doses. Determination of treatment MAC(NM) (MAC(NM-T)) was initiated 90 minutes after start of the CRI. Venous blood samples were collected at the time of each treatment MACNM measurement for determination of plasma concentrations of fentanyl and lidocaine. RESULTS Mean ± SEM overall MAC(NM-B) for the 3 treatments was 2.70 ± 0.27 vol%. The MACNM decreased from MACNM-B to MAC(NM-T) by 39%, 21%, and 55% for fentanyl, lidocaine, and the fentanyl-lidocaine combination, respectively. This decrease differed significantly among treatments. Plasma fentanyl concentration was 3.25 and 2.94 ng/mL for fentanyl and the fentanyl-lidocaine combination, respectively. Plasma lidocaine concentration was 2,570 and 2,417 ng/mL for lidocaine and the fentanyl-lidocaine combination, respectively. Plasma fentanyl and lidocaine concentrations did not differ significantly between fentanyl and the fentanyl-lidocaine combination or between lidocaine and the fentanyl-lidocaine combination. CONCLUSIONS AND CLINICAL RELEVANCE CRIs of fentanyl, lidocaine, and the fentanyl-lidocaine combination at the doses used were associated with clinically important and significant decreases in the MAC(NM) of sevoflurane in dogs.

OBJECTIVE To determine the pharyngeal and laryngeal distribution of radiopaque contrast medium administered orally or via nasopharyngeal catheter to standing horses. ANIMALS 5 healthy adult horses. PROCEDURES A crossover study was conducted. Radiopaque contrast medium (12 mL) was administered orally and via nasopharyngeal catheter to each horse. Pharyngeal and laryngeal distribution of contrast medium was determined by examination of radiographs obtained immediately after administration of contrast medium, compared with those obtained before administration. Regional distribution of contrast medium was graded. Endoscopic examination of the nasopharynx, laryngopharynx, and larynx was performed to confirm radiographic results. RESULTS Examination of radiographs obtained after nasopharyngeal administration revealed contrast medium in the nasopharynx (n = 5), oropharynx (2), laryngopharynx (3), and larynx (5) of the 5 horses. Examination of radiographs obtained after oral administration revealed contrast medium in the oropharynx (n = 4) and larynx (1) of the 5 horses. Endoscopic examination confirmed radiographic findings and was found to be sensitive for detection of contrast medium in the laryngopharynx, whereby detection rates were higher for both administration methods. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that medication administered by use of a nasopharyngeal catheter will result in topical distribution within the nasopharynx, including the dorsal surface of the soft palate, and larynx, although distribution should be evaluated in horses with clinical airway disease to confirm these findings. Oral administration did not result in consistently detectable topical laryngeal distribution but could be used for selected conditions (eg, palatitis).

OBJECTIVE To measure serum homocysteine concentrations in dogs with myxomatous mitral valve disease (MMVD) and identify any association between this variable and stage of MMVD. ANIMALS 53 client-owned dogs with MMVD and 10 healthy control Beagles. PROCEDURES Dogs with MMVD were allocated to 3 groups in accordance with the staging system for chronic valvular heart disease in dogs and cats of the American College of Veterinary Internal Medicine. Blood samples were collected from all dogs, and serum homocysteine and cardiac troponin 1 concentrations were measured by enzyme immunoassay and chemiluminescence immunoassay, respectively. Analyte values were tested for associations with each other and with stage of MMVD. RESULTS A significant correlation was identified between serum homocysteine concentration and stage of MMVD. Mean ± SD concentrations were 6.72 ± 1.65 μmol/L for control dogs, 13.37 ± 4.16 μmol/L for dogs with stage B MMVD, 18.86 ± 6.73 μmol/L for dogs with stage C disease, and 28.26 ± 4.48 μmol/L for dogs with stage D disease. In addition, serum homocysteine concentration was correlated with serum cardiac troponin 1 (r = 0.34) and creatinine (r = 0.46) concentrations, systolic blood pressure (r = 0.57), and left atrium-to-aortic root ratio (r = 0.28), all of which were positively correlated with stage of MMVD. CONCLUSIONS AND CLINICAL RELEVANCE Serum homocysteine concentrations of dogs with MMVD were significantly higher than those of control dogs, and significant correlations were identified between these values and several risk factors for heart failure. Measurement of serum homocysteine concentration may be useful in the prediction of severity of disease in dogs with MMVD.

OBJECTIVE To compare heat generation and mechanical bone damage for tapered and cylindrical transfixation pins during drilling, tapping, and pin insertion in equine third metacarpal bones. SAMPLE 16 pairs of cadaveric equine third metacarpal bones. PROCEDURES For cylindrical pin insertion, a 6.2-mm hole was drilled and tapped with a cylindrical tap, and then a standard 6.3-mm pin was inserted. For tapered pin insertion, a 6.0-mm hole was drilled, reamed with a tapered reamer, and tapped with a tapered tap, and then a 6.3-mm tapered pin was inserted. Paired t tests and 1-way ANOVAs were used to compare heat generation (measured by use of thermocouples and thermography), macrodamage (assessed by use of stereomicroscopy), and microdamage (assessed by examination of basic fuchsin–stained histologic specimens) between cylindrical and tapered pins and between tapered pins inserted to various insertion torques. RESULTS Tapered pin insertion generated less heat but resulted in more bone damage than did cylindrical pin insertion when pins were inserted to the same insertion torque. Insertion of tapered pins to increasing insertion torques up to 16 N•m resulted in increased heat generation and bone damage. CONCLUSIONS AND CLINICAL RELEVANCE Tapered pin insertion resulted in lower heat production than did cylindrical pin insertion. However, tapered pin insertion resulted in greater bone damage, which likely was attributable to differences in the tapered and cylindrical taps. A tapered pin may be preferable to a cylindrical pin for insertion in equine cortical bone provided that improvements in tap design can reduce bone damage during insertion.

OBJECTIVE To examine whether expression of extracellular matrix metalloproteinase inducer (EMMPRIN) can be detected in equine lungs and whether it correlates with matrix metalloproteinase (MMP)-2 and -9 expression in bronchoalveolar lavage fluid (BALF) of horses with chronic inflammation of the lungs (ie, lower airway inflammation [LAI]). ANIMALS 29 horses with signs of chronic respiratory tract disease, which were classified as the LAI (n = 17) and LAI with respiratory distress (RDLAI [12]) groups, and 15 control horses. PROCEDURES BALF, tracheal aspirate, and blood samples were obtained, and EMMPRIN expression was determined from BALF cells and RBCs by use of western blotting. Activities of MMP-2 and -9 were determined with zymography. RESULTS Expression of EMMPRIN protein was identified in BALF cells of all horses. Expression of EMMPRIN protein was highest for the RDLAI group and was correlated with MMP-2 and -9 protein expression, MMP-9 gelatinolytic activity, and airway neutrophilia. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that EMMPRIN was involved in the pathophysiologic processes of asthma in horses. However, additional studies of horses and other species are warranted to elucidate the regulation of EMMPRIN expression in asthmatic lungs.

The aim of the study was to determine the species spectrum of ixodid ticks that infest horses and donkeys in South Africa and to identify those species that act as vectors of disease to domestic livestock. Ticks were collected opportunistically from 391 horses countrywide by their owners or grooms, or by veterinary students and staff at the Faculty of Veterinary Science, University of Pretoria. Ticks were also collected from 76 donkeys in Limpopo Province, 2 in Gauteng Province and 1 in North West province. All the ticks were identified by means of a stereoscopic microscope. Horses were infested with 17 tick species, 72.1% with Rhipicephalus evertsi evertsi, 19.4% with Amblyomma hebraeum and 15.6% with Rhipicephalus decoloratus. Rhipicephalus evertsi evertsi was recovered from horses in all nine provinces of South Africa and R. decoloratus in eight provinces. Donkeys were infested with eight tick species, and 81.6% were infested with R. evertsi evertsi, 23.7% with A. hebraeum and 10.5% with R. decoloratus. Several tick species collected from the horses and donkeys are the vectors of economically important diseases of livestock. Rhipicephalus evertsi evertsi is the vector of Theileria equi, the causative organism of equine piroplasmosis. It also transmits Anaplasma marginale, the causative organism of anaplasmosis in cattle. Amblyomma hebraeum is the vector of Ehrlichia ruminantium, the causative organism of heartwater in cattle, sheep and goats, whereas R. decoloratus transmits Babesia bigemina, the causative organism of babesiosis in cattle.