Objective: To evaluate and compare bone modeling and remodeling in fractured and non-fractured central tarsal bones (CTBs) of racing Greyhounds. Sample: Paired cadaveric tarsi from 6 euthanized racing Greyhounds with right CTB fractures and 6 racing Greyhounds with other nontarsal injuries. Procedures: CTBs were dissected and fractured CTBs were reconstructed. Central tarsal bones were evaluated through standard and nonscreen high-detail radiography, computed tomography, and histologic examination. The bone mineral density (BMD) was calculated adjacent to fracture planes and as a gradient on sagittal computed tomographic images. Sagittal and transverse plane sections of bone were obtained and submitted for subjective histologic assessment. Linear mixed-effects models were used to compare findings. Results: Fractured right CTBs had greater BMD in the dorsal and midbody regions of the sagittal plane sections than did nonfractured CTBs. The BMD ratios from bone adjacent to the dorsal slab fracture planes were not different between fractured and nonfractured right CTBs. Conclusions and Clinical Relevance: Findings supported the existence of site-specific bone adaptation in CTBs of Greyhounds, with modeling and remodeling patterns that were unique to fractured right CTBs. The dorsal and midbody regions of fractured bones had greater BMD, and fractures occurred through these zones of increased BMD.

Objective: To determine whether the extent of disease in dogs with lymphoma can be assessed via flow cytometry and to evaluate the suitability of fine-needle aspirates from the liver and spleen of dogs for flow cytometric examination. Animals: 44 dogs with multicentric B-cell (n = 35) or T-cell lymphoma (9) and 5 healthy control dogs. Procedures: Peripheral blood and bone marrow samples and fine-needle aspirates of lymph node, liver, and spleen were examined via flow cytometry. Logarithmically transformed T-cell–to–B-cell percentage ratio (log[T:B]) values were calculated. Thresholds defined by use of log(T:B) values of samples from control dogs were used to determine extranodal lymphoma involvement in lymphoma-affected dogs; results were compared with cytologic findings. Results: 12 of 245 (5%) samples (9 liver, 1 spleen, and 2 bone marrow) had insufficient cellularity for flow cytometric evaluation. Mean log(T:B) values of samples from dogs with B-cell lymphoma were significantly lower than those of samples from the same site in dogs with T-cell lymphoma and in control dogs. In dogs with T-cell lymphoma, the log(T:B) of lymph node, bone marrow, and spleen samples was significantly higher than in control dogs. Of 165 samples assessed for extranodal lymphoma involvement, 116 (70%) tested positive via flow cytometric analysis; results agreed with cytologic findings in 133 of 161 (83%) samples evaluated via both methods. Conclusions and Clinical Relevance: Results suggested that flow cytometry may aid in detection of extranodal lymphoma involvement in dogs, but further research is needed. Most fine-needle aspirates of liver and spleen were suitable for flow cytometric evaluation.

Objective: To determine whether preanalytic and analytic factors affect evaluation of the urinary protein-to-creatinine (UPC) ratio in dogs. Sample: 50 canine urine samples. Procedures: The UPC ratio was measured to assess the intra-assay imprecision (20 measurements within a single session), the influence of predilution (1:10, 1:20, and 1:100) for urine creatinine concentration measurement, and the effect of storage at room temperature (approx 20°C), 4°C, and −20°C. Results: The coefficient of variation at room temperature determined with the 1:20 predilution was < 10.0%, with the highest coefficients of variation found in samples with a low protein concentration or low urine specific gravity. This variability could result in misclassification of samples with UPC ratios close to the thresholds defined by the International Renal Interest Society to classify dogs as nonproteinuric (0.2), borderline proteinuric (0.21 to 0.50), or proteinuric (> 0.51). A proportional bias was found in samples prediluted 1:10, compared with samples prediluted 1:20 or 1:100. At room temperature, the UPC ratio did not significantly increase after 2 and 4 hours. After 12 hours at room temperature and at 4°C, the UPC ratio significantly increased. The UPC ratio did not significantly change during 3 months of storage at −20°C. Conclusions and Clinical Relevance: The intra-assay precision of the UPC ratio was sufficiently low to avoid misclassification of samples, except for values close to 0.2 or 0.5. The optimal predilution ratio for urine creatinine concentration measurement was 1:20. A 1:100 predilution is recommended in samples with a urine specific gravity > 1.030. The UPC ratio must be measured as soon as samples are collected. Alternatively, samples should be immediately frozen to increase their stability and minimize the risk of misclassification of proteinuria.

Objective: To evaluate the role of the semitendinosus muscle in stabilization of the canine stifle joint. Sample: Left stifle joints collected from cadavers of 8 healthy Beagles. Procedures: Left hind limbs, including the pelvis, were collected. To mimic the tensile force of the quadriceps, gastrocnemius, and semitendinosus muscles, wires were placed under strain between the ends of each muscle. A sensor was used to measure the tensile force in each wire. Specimens were tested in the following sequence: cranial cruciate ligament (CrCL) intact, CrCL transected, released (tensile force of semitendinosus muscle was released in the CrCL-transected stifle joint), and readjusted (tensile force of semitendinosus muscle was reapplied in the CrCL-transected stifle joint). Specimens were loaded at 65.3% of body weight, and tensile force in the wires as well as the cranial tibial displacement were measured. Results: Tensile force for the CrCL-transected condition increased significantly, compared with that for the CrCL-intact condition. Mean ± SD cranial tibial displacement for the CrCL-transected condition was 2.1 ± 1.3 mm, which increased to 7.2 ± 2.3 mm after release of the tensile force in the semitendinosus muscle. Conclusions and Clinical Relevance: Results supported the contention that the semitendinosus muscle is an agonist of the CrCL in the stifle joint of dogs. Moreover, the quadriceps and gastrocnemius muscles may be antagonists of the CrCL. These findings suggested that the risk of CrCL rupture may be increased by diseases (such as cauda equina syndrome) associated with a decrease in activity of the semitendinosus muscle.

Objective: To determine the efficacy of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy in weanling foals. Animals: 12 healthy weanling foals. Procedures: Foals were randomly assigned to a vaccinated, nonvaccinated, or control group. Vaccinated foals received an avirulent porcine L intracellularis frozen-thawed vaccine intrarectally 60 and 30 days prior to experimental challenge. On day 1, vaccinated and nonvaccinated foals were challenged via nasogastric intubation with a virulent heterologous isolate of L intracellularis. Control foals were not challenged. Clinical observation and ultrasonographic evaluation of the small intestine were performed, and body weight, serum concentration of total solids, fecal excretion of L intracellularis, and seroconversion were measured for each foal until day 56. Diseased foals were treated with antimicrobials and supportive are. Results: None of the 4 vaccinated foals developed clinical disease following challenge with virulent L intracellularis. Three of 4 nonvaccinated foals developed moderate to severe clinical signs compatible with proliferative enteropathy, hypoproteinemia, and thickened small intestinal loops. Vaccinated foals had significantly less fecal shedding of L intracellularis than nonvaccinated foals. Serologic responses between vaccinated and nonvaccinated foals after challenge were similar. Control foals remained clinically unaffected with no evidence of fecal shedding and seroconversion. Conclusions and Clinical Relevance: Intrarectal administration of a commercial avirulent porcine vaccine against L intracellularis resulted in complete protection against proliferative enteropathy in the foals in this study and may also reduce environmental contamination with the organism on endemic farms.

Objective: To establish practical doses and administration frequencies of fondaparinux for cats that would approximate human therapeutic peak and trough plasma anti–factor Xa activities for thromboprophylaxis (TP) and thrombosis treatment (TT) protocols. Animals: 6 healthy adult purpose-bred cats. Procedures: Dosage protocols for TP and TT were selected on the basis of a single compartment pharmacokinetic model incorporating data from humans but modified to account for the higher body weight–normalized cardiac output of cats. Fondaparinux was administered at 0.06 mg/kg, SC, every 12 hours (TP) for 7 days in one session, and 0.20 mg/kg, SC, every 12 hours (TT) for 7 days in another, with a minimum of 1 week separating the sessions. Plasma anti–factor Xa activity was measured before fondaparinux administration (day 1) and at 2 (peak) and 12 (trough) hours after drug administration on days 1 and 7. Platelet aggregation and thromobelastographic (TEG) parameters were also measured 2 hours after drug administration on day 7. Results: Peak plasma anti–factor Xa activities on day 7 for TP (median, 0.59 mg/L; range, 0.36 to 0.77 mg/L) and TT (median, 1.66 mg/L; range, 1.52 to 2.00 mg/L) protocols were within therapeutic ranges for humans. However, only the TP protocol achieved trough anti–factor Xa activity considered therapeutic in humans (median, 0.19 mg/L; range, 0.00 to 0.37 mg/L) on day 7. There were significant changes in the TEG parameters at peak for the TT protocol, suggesting a hypocoagulable state. No significant changes in platelet aggregation were evident for either protocol. Conclusions and Clinical Relevance: A fondaparinux dosage of 0.06 or 0.20 mg/kg, SC, every 12 hours, was sufficient to achieve a peak plasma anti–factor Xa activity in cats that has been deemed therapeutic in humans. This study provided preliminary data necessary to perform fondaparinux dose-determination and clinical efficacy studies.

Objective: To immunohistochemically evaluate matrix metalloproteinase (MMP)-9 expression in benign and malignant mammary gland tumors (MMTs) in dogs and relate expression to prognostic factors and patient outcome. Animals: 118 female dogs with naturally occurring mammary gland tumors and 8 dogs without mammary gland tumors. Procedures: 24 benign mammary gland tumors and 94 MMTs (1/affected dog) were obtained during surgical treatment; control mammary gland tissue samples were collected from unaffected dogs after euthanasia for reasons unrelated to the study. Tumors were evaluated for proliferation, invasive growth, histologic grade, and metastatic capacity; expression of MMP-9 was determined immunohistochemically, and its relationship with clinical and histologic findings was investigated. For dogs with MMTs, follow-up continued for 2 years; data were used to compute overall survival time and disease-free interval and construct survival curves. Results: MMTs had significantly higher MMP-9 expression in stromal cells and in neo-plastic cells than did the benign neoplasms. Stromal MMP-9 expression was also higher in highly proliferative tumors and in tumors with invasive growth, high histologic grade, and metastatic capacity. Furthermore, tumors from patients with shorter overall survival times and disease-free intervals had higher expression of MMP-9 in stromal cells. Conclusions and Clinical Relevance: In dogs with MMTs, level of MMP-9 expression by stromal cells was related to factors of poor prognosis and shorter overall survival times and disease-free intervals. These results suggested that MMP-9 produced by tumor-adjacent stromal cells contributed to MMT progression in female dogs and that assessment of MMP-9 expression may be a valuable prognostic factor.

Objective: To compare the pharmacokinetics of a novel bioadhesive gel formulation of midazolam after intranasal (IN) administration with that of midazolam solution after IN, IV, and rectal administration to dogs. Animals: 10 (5 males and 5 females) healthy adult Beagles. Procedures: Dogs were assigned to 4 treatment groups for a crossover study design. Initially, midazolam solution (5 mg/mL) was administered (0.2 mg/kg) IV to group 1, rectally to group 2, and IN to group 3; a 0.4% hydroxypropyl methylcellulose midazolam gel formulation (50 mg/mL) was administered (0.2 mg/kg, IN) to group 4. Each dog received all 4 treatments; there was a 7-day washout period between subsequent treatments. Blood samples were collected before and after midazolam administration. Plasma concentration of midazolam was determined by use of high-performance liquid chromatography. Results: The peak plasma concentration after IN administration of the gel formulation was significantly higher than that after IN and rectal administration of the solution. Mean ± SD time to peak concentration was 11.70 ± 2.63 minutes (gel IN), 17.50 ± 2.64 minutes (solution IN), and 39 ± 14.49 minutes (solution rectally). Mean bioavailability of midazolam was 70.4% (gel IN), 52.0% (solution IN), and 49.0% (solution rectally). Bioavailability after IN administration of the gel formulation was significantly higher than that after IN and rectal administration of the solution. Conclusions and Clinical Relevance: IN administration of midazolam gel was superior to both IN and rectal administration of midazolam solution with respect to peak plasma concentration and bioavailability.

The effects of selenium (Se) supplementation and source on equine immune function have not been extensively studied. This study examined the effects of oral Se supplementation and Se source on aspects of innate and adaptive immunity in horses. Fifteen horses were assigned to 1 of 3 groups (5 horses/group): control, inorganic Se (sodium selenite), organic Se (Se yeast). Immune function tests performed included: lymphocyte proliferation in response to mitogen concanavalin A, neutrophil phagocytosis, antibody production after rabies vaccination, relative cytokine gene expression in stimulated lymphocytes [interferon gamma (IFNγ), interleukin (IL)-2, IL-5, IL-10, tumor necrosis factor alpha (TNFα)], and neutrophils (IL-1, IL-6, IL-8, IL-12, TNFα). Plasma, red blood cell Se, and blood glutathione peroxidase activity were measured. Plasma and red blood cell Se were highest in horses in the organic Se group, compared with that of inorganic Se or control groups. Organic Se supplementation increased the relative lymphocyte expression of IL-5, compared with inorganic Se or no Se. Selenium supplementation increased relative neutrophil expression of IL-1 and IL-8. Other measures of immune function were unaffected. Dietary Se content and source appear to influence immune function in horses, including alterations in lymphocyte expression of IL-5, and neutrophil expression of IL-1 and IL-8.

Objective-To measure the effects of tidal volume, ventilatory frequency, and oxygen insufflation flow on the fraction of inspired oxygen in cadaveric horse heads attached to a lung model. Sample-8 heads of equine cadavers. Procedures-Each cadaveric horse head was intubated with a nasotracheal tube that extended into the proximal portion of the trachea. Oxygen was delivered through an oxygen catheter contained within and extending to the tip of the nasotracheal tube. The trachea was connected to the lung model by use of a spiral-wound hose with a sampling adaptor. Eight treatment combinations involving 2 tidal volumes (5 and 8 L), 2 ventilatory frequencies (6 and 12 mechanical breathes/min), and 2 insufflation rates (10 and 15 L/min) were applied to each head. Hand-drawn inspired gas samples were collected and analyzed for oxygen concentrations. Results-The fraction of inspired oxygen (measured at mid trachea) ranged from 26.8% to 39.4%. Fraction of inspired oxygen was significantly higher with a smaller tidal volume, lower ventilatory frequency, and higher insufflation rate. Conclusions and Clinical Relevance-In the study model, measured fraction of inspired oxygen varied with ventilatory pattern as well as oxygen insufflation rate. Clinically, this information could be beneficial for interpretation of data regarding arterial blood gases and hemoglobin saturation and in making appropriate oxygen insufflation decisions for anesthetized horses that are breathing room air.