Objective: To determine whether the reported drug-drug interaction between the flea medication spinosad and ivermectin is attributable to inhibition of P-glycoprotein by spinosad. Animals: 6 healthy adult dogs with the ABCB1 wildtype genotype. Procedures: The study was conducted as a prospective, masked, randomized crossover design. Six dogs were allocated to 2 groups; each dog served as its own control animal. Dogs in one of the groups received spinosad at the manufacturer's recommended dose; the other group received no treatment. Forty-eight hours later, scintigraphic imaging of the head and abdomen were performed with the radiolabeled P-glycoprotein substrate methoxy-isobutyl-isonitrile (sestamibi) in both groups of dogs. After a washout period of 60 days, the dogs in each group received the alternate treatment, and scintigraphic imaging again was performed 48 hours later. Gallbladder-to-liver and brain-to-neck musculature ratios of technetium Tc 99m sestamibi were calculated for each dog and compared between treatments. Results: No significant differences in gallbladder-to-liver or brain-to-neck musculature ratios were found between treatments. Conclusions and Clinical Relevance: Results provided evidence that spinosad did not inhibit P-glycoprotein function 48 hours after spinosad was administered at the manufacturer's recommended dose. Further investigations will be necessary to elucidate the mechanism of the reported toxic interaction between spinosad and ivermectin.

Objective: To evaluate onset of protection induced by modified-live virus (MLV) bovine viral diarrhea virus (BVDV) vaccine administered 7, 5, or 3 days before inoculation with type 1b BVDV (strain NY-1). Animals: 40 calves. Procedures: Calves were assigned to 4 groups: an unvaccinated control group or groups vaccinated with MLV vaccine containing BVDV types 1a and 2 at 7, 5, or 3 days, before inoculation with NY-1 BVDV. Blood samples were collected for leukocyte counts, serum virus neutralization, and virus isolation (VI); nasal swab specimens (NSSs) were obtained for VI, and rectal temperatures were monitored for 14 days after inoculation. Results: No significant differences in leukocyte counts or rectal temperatures were detected after BVDV inoculation in vaccinated calves. Vaccinated calves had reduced viremia and viral shedding after inoculation, compared with results for unvaccinated calves. On day 5 after inoculation, a higher proportion of calves vaccinated 3 days before inoculation had positive VI from NSSs, compared with NSS VI results for calves vaccinated 5 and 7 days before inoculation. Unvaccinated calves had leukopenia on days 3, 5, and 6 and had higher rectal temperatures on days 7 and 8 after inoculation, compared with temperatures before inoculation. All unvaccinated calves had ≥ 1 positive VI result from NSSs 3 to 11 days after inoculation, and 4 became viremic. Conclusions and Clinical Relevance: MLV BVDV vaccine prevented fever, viremia, and leukopenia in calves challenge inoculated with NY-1 BVDV. A high proportion of calves vaccinated 3 days before inoculation shed BVDV after inoculation.

Objective: To describe and measure histologic features of midcarpal joint cartilage defects in Thoroughbreds and evaluate the influence of early conditioning exercise on defect development. Sample: 24 midcarpal joints from twelve 18-month-old Thoroughbreds. Procedures: Midcarpal joints from 12 horses (6 exercised spontaneously at pasture only and 6 given additional conditioning exercise beginning at a mean age of 3 weeks were evaluated. Gross cartilage defects were assessed histologically. Third and radial carpal bones were categorized with regard to the presence or absence of calcified cartilage (CC) abnormalities at the dorsoproximal and dorsodistal articular surfaces, respectively; histomorphometric assessment and statistical analysis were conducted for the third carpal bone. Results: Number and severity of defects did not appear different between exercise groups. Nine third or radial carpal bones had thickened CC with microcracks, matrix and osteochondral junction changes, and increased vascularity, without histologic changes in the hyaline cartilage. Third carpal bones with CC abnormalities had significantly thicker CC (452 vs 228 μm) than did those without CC abnormalities in the evaluated region. However, in the same region, there were no significant differences in hyaline cartilage thickness (681 vs 603 μm), vascular channel area in the subchondral bone (624,894 vs 490,320 μm2), or number of vascular channels (15.9 vs 18.0). Conclusions and Clinical Relevance: Early exercise did not appear to influence the distribution or severity of cartilage defects in the midcarpal joint. Calcified cartilage abnormalities beneath the undisrupted hyaline cartilage in the dorsoproximal aspect of the third carpal bone may represent the first changes in the pathogenesis of midcarpal osteochondral disease.

Objective: To determine whether vaccine virus can be detected by use of reverse transcriptase (RT)-PCR assays for pooled and individual skin samples obtained from cattle after vaccination with a commercially available modified-live bovine viral diarrhea virus (BVDV) vaccine. Animals: 12 BVDV-seropositive steer calves and 7 BVDV-seronegative (antibody titer < 1:4) heifers; all cattle were free of persistent infection with BVDV. Procedures: 2 experiments were conducted. Cattle were vaccinated on day 0 with a commercially available modified-live BVDV vaccine. Skin samples were collected on days 0, 3 to 14, 16, and 18 for virus detection by use of RT-PCR assay on individual and pooled samples. In addition, blood samples and nasal swab specimens were collected for virus isolation. Results: All cattle, regardless of serologic status, had negative results for BVDV as determined by use of RT-PCR assay of individual and pooled skin samples. Virus was detected via virus isolation in serum or the buffy coat in 5 of 7 heifers that were seronegative when vaccinated. Conclusions and Clinical Relevance: These findings indicated that it would be unlikely to detect BVDV vaccine virus in skin by use of RT-PCR assay of individual or pooled skin samples obtained from cattle after vaccination with a commercially available modified-live BVDV vaccine. Veterinarians and producers should be confident that positive test results for BVDV on skin samples would not likely be caused by the vaccination virus after administration of a modified-live virus vaccine.

Objective: To examine the effects of in vitro exposure to solutions of autologous horse blood (AHB) and autologous horse serum (AHS) on expressions of selected cytokine genes in equine primary bronchial epithelial cell (BEC) cultures and to contrast these responses to those induced in BEC cultures by endotoxin and hay dust. Sample: BEC cultures established from bronchi of 6 healthy horses. Procedures: 5-day-old BEC cultures were treated with PBS solution, AHB (2 concentrations), AHS, hay dust solution, and lipopolysaccharide solution for 24 hours. Gene expressions of interleukin (IL)-8, IL-1β, chemokine (C-X-C motif) ligand 2 (CXCL2), and glyceralde-hyde-3-phosphate dehydrogenase were subsequently measured with a kinetic PCR assay. Results: With the exception of AHS, all treatments of the BECs resulted in upregulation of each target gene expression relative to its expression in cultures exposed to PBS solution. Treatment with AHB induced a dose-dependent increase of each target gene, with IL-1β expression increasing the most (> 1,200-fold increase). Lipopolysaccharide and hay dust solution treatments each resulted in 20-fold increases in IL-8 and IL-1β gene expressions. Lipopolysaccharide and hay dust solution treatments also resulted in a 7- and 8-fold increase in CXCL2 gene expression, respectively. The increases in IL-8 and CXCL2 gene expressions following treatment with the higher concentration of blood were equivalent to those associated with hay dust solution or lipopolysaccharide. Conclusions and Clinical Relevance: Results suggested that chemokine expression by cultured equine BECs following exposure to pulmonary hemorrhage conditions may contribute to the development of inflammatory airway disease in horses.

The objective of this study was to evaluate the effect of a single joint lavage with 7.2% or 15% hypertonic saline solutions (HSS) on the tarsocrural joints of healthy calves. The tarsi of 10 calves were randomly lavaged with 7.2% HSS, 15% HSS, or isotonic saline. Synovial fluid samples were collected aseptically on days 1 (before joint lavage), 2, 3, 4, and 8 for complete cytological analysis. Lameness, joint swelling, and pain were recorded daily. Calves were euthanized on day 8 for gross and histological analyses of synovial membranes and articular cartilage. Synovitis was evaluated using a scoring system reflecting inflammatory changes in synovial membranes. Joints irrigated with HSS were more distended and painful compared with isotonic control joints. Swelling decreased consistently in the joints lavaged with 7.2% HSS, whereas it remained unchanged in joints lavaged with 15% HSS. Slight to moderate lameness was observed in the joints lavaged with 15% HSS. In comparison to isotonic saline joints, total protein concentration was significantly increased on day 2 and 3 for the joints lavaged with 7.2% HSS (P ≤ 0.01) and on days 2, 3, and 4 in the joints lavaged with 15% HSS (P ≤ 0.0006). Gross and histological findings revealed that synovitis was more severe in the joints lavaged with 15% HSS but variable in the joints lavaged with 7.2% HSS. No significant differences were observed for the articular cartilage. Fifteen percent HSS is not recommended for joint lavage. Although irrigation with 7.2% HSS may induce a variable synovitis, it was found appropriate for joint lavage. Its effects on septic joints remain undetermined.

An optimized protocol was developed for the simultaneous detection and differentiation of Haemophilus parasuis, Streptococcus suis, and Mycoplasma hyorhinis in formalin-fixed, paraffin-embedded (FFPE) tissues with multiplex nested polymerase chain reaction (PCR). This method also determines the prevalence of these bacteria in pigs with polyserositis. DNA extraction with a combination of a commercial reagent and proteinase K resulted in more frequent detection of the pathogens than DNA extraction with proteinase K alone. Among FFPE tissue samples from 312 cases of polyserositis in which at least 1 bacterial species was detected, multiplex nested PCR detected H. parasuis in 239 (77%), S. suis in 124 (40%), and M. hyorhinis in 40 (13%). The disease was caused by a single pathogen in 224 (72%) of the cases and multiple pathogens in 88 (28%). Among the pigs positive for H. parasuis, S. suis, and M. hyorhinis by multiplex nested PCR, the pathogen was isolated from only 11%, 35%, and 28%, respectively. Therefore, the PCR protocol developed in this study is a useful diagnostic method when samples are negative after isolation methods and even for samples in which only 1 pathogen was isolated.

Objective-To assess gene expressions of cyclooxygenase-1 and -2 in oral, glandular gastric, and urinary bladder mucosae and determine the effect of oral administration of phenylbutazone on those gene expressions in horses. Animals-12 healthy horses. Procedures-Horses were allocated to receive phenylbutazone or placebo (6 horses/group); 1 placebo-treated horse with a cystic calculus was subsequently removed from the study, and those data were not analyzed. In each horse, the stomach and urinary bladder were evaluated for ulceration via endoscopy before and after experimental treatment. Oral, glandular gastric, and urinary bladder mucosa biopsy specimens were collected by use of a skin punch biopsy instrument (oral) or transendoscopically (stomach and bladder) before and after administration of phenylbutazone (4.4 mg/kg, PO, q 12 h) in corn syrup or placebo (corn syrup alone) for 7 days. Cyclooxygenase-1 and -2 gene expressions were determined (via quantitative PCR techniques) in specimens collected before and after the 7-day treatment period and compared within and between groups. Prior to commencement of treatment, biopsy specimens from 7 horses were used to compare gene expressions among tissues. Results-The cyclooxygenase-1 gene was expressed in all tissues collected. The cyclooxygenase-2 gene was expressed in the glandular gastric and bladder mucosae but not in the oral mucosa. Cyclooxygenase gene expressions were unaffected by phenylbutazone administration. Conclusions and Clinical Relevance-Cyclooxygenase-2 was constitutively expressed in glandular gastric and bladder mucosae but not in the oral mucosa of healthy horses. Oral administration of phenylbutazone at the maximum recommended dosage daily for 7 days did not affect cyclooxygenase-1 or -2 gene expression.

Objective-To investigate the ability of ABT-116 (a proprietary antagonist of transient receptor potential vanilloid type 1) administered at 2 doses to attenuate lameness in dogs with experimentally induced urate synovitis. Animals-8 purpose-bred mixed-breed dogs. Procedures-n a 4-way crossover study, dogs orally received each of low-dose ABT-116 treatment (LDA; 10 mg/kg), high-dose ABT-116 treatment (HDA; 30 mg/kg), firocoxib (5 mg/kg), and no treatment (nontreatment) once a day for 2 days, in a randomly assigned order. Synovitis was induced on the second day of each treatment period by intra-articular injection of either stifle joint with sodium urate, alternating between joints for each treatment period, beginning with the left stifle joint. Ground reaction forces, clinical lameness scores, and rectal temperature were assessed before the injection (baseline) and at various points afterward. Results-Lameness scores at the 2-, 6-, and 12-hour assessment points were higher than baseline scores for HDA and nontreatment, whereas scores at the 2- and 6-hour points were higher than baseline scores for LDA. For firocoxib, there was no difference from baseline scores in lameness scores at any point. Compared with baseline values, peak vertical force and vertical impulse were lower at 2 and 6 hours for HDA and nontreatment and at 2 hours for LDA. No changes in these values were evident for firocoxib. The HDA or LDA resulted in higher rectal temperatures than did treatment with firocoxib or nothing, but those temperatures did not differ among treatments. Conclusions and Clinical Relevance-HDA had no apparent effect on sodium urate–induced lameness; LDA did attenuate the lameness but not as completely as firocoxib treatment. High rectal temperature is an adverse effect of oral ABT-116 administration that may be of clinical concern.

The objective of this study was to evaluate the bactericidal effect of shock waves (SWs) on gram-negative or gram-positive monocultured biofilms grown on an orthopedic implant in vitro. Cortical bone screws were individually cultured with Escherichia coli or Staphylococcus epidermidis to produce a biofilm. In each run of 8 screws, 6 screws were treated with shock waves and then sonicated to disrupt the biofilm. One screw was sonicated only and one was not shock waved or sonicated before sampling for plate count dilutions. Post-treatment serial dilutions and plate counts were done on an aliquot from the vial containing each screw to obtain the number of colony-forming units (CFUs). Shock waves were at a constant energy of 0.15 mJ/mm2. Pulse number and screw orientation were varied. A linear mixed-effects model was used with “treatment” as a fixed effect and “run” as a random effect. Pairwise comparisons of treatments were performed with Tukey-Cramer’s adjustment for P-values. Sonicated plate counts were greater than nonsonicated counts for each run. When all sonicated screws were compared to all nonsonicated screws, the counts were significantly increased (P = 0.0091). For each paired comparison between sonicated and shock wave treatment, the only significant difference was in the S. epidermidis biofilm treated at 2000 pulses in a horizontal position, which increased the post-treatment count (P = 0.0445). No bactericidal effects were seen on monocultured biofilms on cortical bone screws treated with shock waves.