Objective—To assess agreement between anesthetic agent concentrations measured by use of an infrared anesthetic gas monitor (IAGM) and refractometry. Sample—4 IAGMs of the same type and 1 refractometer. Procedures—Mixtures of oxygen and isoflurane, sevoflurane, desflurane, or N2O were used. Agent volume percent was measured simultaneously with 4 IAGMs and a refractometer at the common gas outlet. Measurements obtained with each of the 4 IAGMs were compared with the corresponding refractometer measurements via the Bland-Altman method. Similarly, Bland-Altman plots were also created with either IAGM or refractometer measurements and desflurane vaporizer dial settings. Results—Bias ± 2 SD for comparisons of IAGM and refractometer measurements was as follows: isoflurane, −0.03 ± 0.18 volume percent; sevoflurane, −0.19 ± 0.23 volume percent; desflurane, 0.43 ± 1.22 volume percent; and N2O, −0.21 ± 1.88 volume percent. Bland-Altman plots comparing IAGM and refractometer measurements revealed nonlinear relationships for sevoflurane, desflurane, and N2O. Desflurane measurements were notably affected; bias ± limits of agreement (2 SD) were small (0.1 ± 0.22 volume percent) at < 12 volume percent, but both bias and limits of agreement increased at higher concentrations. Because IAGM measurements did not but refractometer measurements did agree with the desflurane vaporizer dial settings, infrared measurement technology was a suspected cause of the nonlinear relationships. Conclusions and Clinical Relevance—Given that the assumption of linearity is a cornerstone of anesthetic monitor calibration, this assumption should be confirmed before anesthetic monitors are used in experiments.

This was a preliminary investigation of the use of lithium to prevent lomustine-induced myelosuppression. Four 10 to 11 kg beagles received lomustine 20 to 30 mg, PO, q3wk, with cephalexin prophylaxis. Two dogs also received lithium, 150 to 300 mg, PO, q12h. Lithium blood concentrations fluctuated in and out of therapeutic interval. Lithium was discontinued in one dog in week 13, and in the other dog in week 38, due to toxicoses. All dogs developed grade 1 to 4 neutropenia after each lomustine treatment. In dogs receiving lomustine only, platelet concentrations decreased from 274 and 293 × 10(9)/L in week 1, to 178 and 218 × 10(9)/L in weeks 38 and 13, respectively. In dogs receiving lomustine and lithium, platelet concentrations decreased from 351 and 288 × 10(9)/L in week 1, to 214 and 212 × 10(9)/L, in weeks 36 and 13, respectively. Lithium did not prevent lomustine-induced myelosuppression and had important side-effects.

Few antimicrobials are licensed for use in sheep in Canada, and the range of indications is narrow. Treatment in an “extra-label” manner may be ineffective. In addition, potentially harmful drug residues in food-animal products and antimicrobial resistance in bacteria may be associated with extra-label drug use (ELDU). No data had been documented on drug use, specifically antimicrobial use (AMU), in Ontario sheep, although it was thought that much use was extra-label. This study investigated AMU and ELDU on 49 lamb-producing Ontario sheep farms. Data were prospectively collected over 12 months from the participating farms, and farm-level practices were ascertained with a questionnaire. Treatment-level and farm-level variables were investigated for associations with rates of AMU by means of Poisson rate regression models fit with a generalized estimating equation to control for clustering at the farm level. Antimicrobials with high mean exposure rates included chlortetracycline (in feed), penicillins, and oxytetracycline. The exposure rate in lambs was significantly lower (P < 0.01) with antimicrobial treatment of systemic signs, respiratory disease, or wound or injury than with treatment of other reported diseases or conditions; it was also significantly lower with 3 or more lambing periods per year (α = 0.05). The exposure rate in adult sheep was significantly lower with treatment of 5 of the 6 most prevalent diseases or conditions (α = 0.05) and significantly higher with producer decision to treat and producer experience of 20 y or greater. Rates of using antimicrobials not licensed for use in sheep were high, as was extra-label use of licensed antimicrobials. Diseases reportedly treated most often with antimicrobials (e.g., systemic signs, mastitis) were significantly associated with lower rates of ELDU (α = 0.05). Compared with the rates in adult sheep, the mean rate of use of nonlicensed antimicrobials was similar in the lambs, whereas the mean rate of extra-label use of licensed antimicrobials was lower among the lambs. The results are useful in determining if public health concerns about antimicrobial use in Ontario sheep are warranted and in creating drug use and licensure strategies for the Canadian sheep industry.

Objective—To evaluate markers of in vivo platelet function (urinary 11-dehydro-thromboxane B2 [11-dehydroTXB2] and 2,3-dinorTXB2) and assess their response to administration of 2 commonly used dosages of aspirin in healthy dogs. Animals—20 healthy dogs. Procedures—Urine was collected prior to aspirin administration and on the morning following the last evening administration. Twenty dogs received aspirin (1 mg/kg, PO, q 24 h) for 7 consecutive doses. After a washout period of 5 months, 10 dogs received a single dose of aspirin (10 mg/kg, PO). Concentrations of urinary thromboxane metabolites 11-dehydroTXB2 and 2,3-dinorTXB2 were measured via ELISA, and values were normalized to urine creatinine concentration. Results—Median baseline 11-dehydroTXB2 concentrations were 0.38 ng/mg of creatinine (range, 0.15 to 1.13 ng/mg). Mean ± SD baseline 2 at a 3-dinorTXB2 concentrations were 6.75 ± 2.77 ng/mg of creatinine. Administration of aspirin at a dosage of 1 mg/kg, PO, every 24 hours for 7 days did not significantly decrease urinary 11-dehydroTXB2 concentration, but administration of the single aspirin dose of 10 mg/kg did significantly decrease 11-dehydroTXB2 concentration by a median of 45.5% (range, 28.2% to 671%). Administration of the 1 mg/kg aspirin dosage significantly decreased urinary 2,3-dinorTXB2 concentration by a mean ± SD of 33.0 ± 23.7%. Administration of the single aspirin dose of 10 mg/kg also significantly decreased 2,3-dinorTXB2 concentration by a mean ± SD of 46.7 ± 12.6%. Conclusions and Clinical Relevance—Aspirin administration (1 mg/kg/d) may be insufficient for reliable platelet inhibition in healthy dogs.

Objective—To evaluate distortion product otoacoustic emission (DPOAE) measurements in puppies with normal hearing. Animals—23 clinically normal 7.5-to 10.5-week-old puppies. Procedures—A cross-sectional study was performed. The DPOAE measurements were obtained with a commercially available distortion product otoacoustic measurement system and were performed in a quiet, non-sound-attenuated room. All measurements were obtained from alert puppies and were repeated 1 or 2 times to ensure that the measurements were replicable. Results that were a minimum of 8 dB higher than the noise floor were accepted. Values from the first trial in which emissions were obtained at all test frequencies were used for analysis. Results—Otoacoustic emission measurements were easily obtained, robust, reliable, and consistent with auditory brainstem response and behavioral results. Conclusions and Clinical Relevance—Hearing screening in alert puppies can be accomplished reliably and rapidly with otoacoustic emissions testing. Results supported the possibility of the use of DPOAE measurement in hearing screening of dogs.

Objective: To evaluate the in vitro susceptibility of various field isolates of Mycobacterium avium subsp paratuberculosis (MAP) to gallium nitrate. Sample: 10 isolates of MAP, including 4 isolated from cattle, 2 isolated from bison, 1 isolated from an alpaca, and 3 isolated from humans. Procedures: The in vitro susceptibility to gallium nitrate was tested by use of broth culture with detection of MAP growth by means of a nonradiometric automated detection method. For each MAP isolate, a series of 7 dilutions of gallium nitrate (concentrations ranging from 200 to 1,000μM) were tested. Gallium nitrate was considered to have caused 90% and 99% inhibition of the MAP growth when the time to detection for culture of the MAP stock solution and a specific concentration of gallium nitrate was delayed and was similar to that obtained for culture of the MAP stock solution (without the addition of gallium nitrate) diluted 1:10 and 1:100, respectively. Results: Gallium nitrate inhibited MAP growth in all 10 isolates. The susceptibility to gallium nitrate was variable among isolates, and all isolates of MAP were inhibited in a dose-dependent manner. Overall, the concentration that resulted in 90% inhibition ranged from < 200μM for the most susceptible isolates to 743μM for the least susceptible isolates. Conclusions and Clinical Relevance: Gallium nitrate had activity against all 10 isolates of MAP tested in vitro and could potentially be used as a prophylactic agent to aid in the control of MAP infections during the neonatal period.

Objective—To compare the efficacy and adverse effects of sustained-release (SR) buprenorphine following SC administration and buprenorphine following oral transmucosal (OTM) administration in cats undergoing ovariohysterectomy. Animals—21 young healthy female cats. Procedures—As part of anesthetic premedication (0 hours), 10 cats received buprenorphine (0.02 mg/kg) via OTM administration with additional doses at 12, 24, 36, 48, and 60 hours and 11 cats received an equivalent total dose as a single SC injection of SR buprenorphine (0.12 mg/kg). The SR product contained buprenorphine hydrochloride in a proprietary SR matrix. All other anesthetic drugs and a single postoperative dose of meloxicam were administered similarly to all cats. Behavioral and physiologic variables were recorded, and signs of pain were assessed by use of 2 pain assessment scales and von anesthesia (RFA), and at 12, 24, 36, 48, 60, and 72 hours. Results—Heart rate increased and temperature (determined via microchip transponder thermometry) decreased from baseline values during RFA in both groups. Compared with baseline values, pain scores were increased during RFA and at the 12- and 24-hour time points in both groups; von Frey scores were higher during RFA. Behavioral and physiologic variables did not differ significantly between groups at any time point. Conclusions and Clinical Relevance—In cats undergoing ovariohysterectomy, SC administration of a preoperative dose of SR buprenorphine appeared to have comparable efficacy and adverse effect profile as that of twice-daily OTM administration of buprenorphine before and after surgery.

Objective—To describe the effects of prednisone and acetylsalicylic acid (ASA) on results of thromboelastography in healthy dogs. Animals—16 male mixed-breed dogs. Procedures—Dogs were randomly assigned to 3 treatment groups (4 dogs/group) that received prednisone (median dose, 2.07 mg/kg), ASA (median dose, 0.51 mg/kg), or both drugs, PO, every 24 hours from days 0 through 6. Another group received no treatment (control dogs; n = 4). Thromboelastography variables (reaction time, clotting time, α-angle, maximum amplitude [MA], global clot strength, coagulation index, and percentage of clot lysis at 60 minutes [CL60]) were evaluated in blood samples collected (prior to drug administration in treated dogs) on days 0 (baseline), 2, 4, and 6. Results—Administration of ASA alone did not alter TEG variables. For treatment effect, mean global clot strength was increased in the prednisone and drug combination groups, compared with values for control dogs; MA was also increased in the prednisone and drug combination groups, compared with that of controls. For treatment-by-time effect, median CL60 was increased in the prednisone group on day 6, compared with baseline value in the same dogs and with median CL60 of the control group on day 6. Median CL60 was also increased in the drug combination group on day 6, compared with the baseline value and with that of the control group on day 6. Conclusions and Clinical Relevance—Prednisone administered at approximately 2 mg/kg/d, PO, for 7 days with or without concurrently administered ASA increased clot strength and decreased clot lysis in healthy dogs.

Objective—To compare composition and colony formation of bone marrow mononuclear cells (BMMCs) harvested from dogs by means of a new perfusion method and the conventional aspiration method. Animals—7 healthy adult Beagles. Procedures—BMMCs were collected from the humeri and femurs of Beagles via perfusion and aspiration methods. Flow cytometric analysis was performed to quantify the presence of contaminant cells from the peripheral blood and the percentage of CD34+ progenitor cells in the BMMCs. A CFU assay was conducted to determine the number of progenitor cells in the BMMCs. Results—The perfusion method was safely performed in all 7 dogs. Flow cytometric analysis revealed that the percentages of contaminant CD3+CD4+, CD3+CD8+, and CD21 + lymphocytes in BMMCs obtained via perfusion were significantly lower than percentages obtained via aspiration. The percentage of CD34+ cells obtained via perfusion was significantly higher than that obtained via aspiration. In addition, perfusion yielded a significantly higher CFU count than did aspiration. Conclusions and Clinical Relevance—The perfusion method used in this study can minimize the contamination of bone marrow samples with peripheral blood and was a more efficient means for collecting canine bone marrow progenitor cells than the conventional aspiration method. Therefore, the perfusion method can be more suitable than aspiration for harvesting bone marrow cells for transplantation in dogs.

Objective—To evaluate expression of matrix metalloproteinase (MMP)-2 and -9 and membrane-type 1 MMP (MT1-MMP) in melanocytomas and malignant melanomas of dogs, analyze in vitro production of MMPs by canine melanoma cell lines and primary dermal fibroblasts, and investigate mutual communication between tumor cells and fibroblasts and the influence of collagen on MMP regulation. Sample—35 biopsy specimens from melanocytic tumors and primary dermal fibroblasts of dogs and 3 canine melanoma cell lines (CML-1, CML-10c2, and CML-6M). Procedures—MMP-2, MMP-9, and MT1-MMP were detected in tumor samples by use of unohistochemical analysis. In vitro production was analyzed via reverse transcriptase-PCR assay, immunocytochemical analysis, zymography, and immunoblotting. Results—MMP-9 was overexpressed in malignant melanomas, compared with expression in melanocytomas, whereas no significant differences in MMP-2 and MT1-MMP immunostaining were detected. Stromal cells also often had positive staining results. In vitro, all 3 melanoma cell lines and dermal fibroblasts had evidence of MMP-2 and MT1-MMP, but only melanoma cells had evidence of MMP-9. Coculture of CML-1 or CML-10c2 cells and dermal fibroblasts induced an increase in expression of the active form of MMP-2. Culture of melanoma cells on type I collagen increased the activation state of MT1-MMP. Conclusions and Clinical Relevance—MMP-9 expression was increased in malignant melanomas of dogs. Stromal cells were a source for MMPs. Stromal cells, in combination with matrix components such as type I collagen, can interact with tumor cells to regulate MMP production. Information about MMP production and regulation could help in the development of new treatments.