Evaluation of canine tympanic membrane integrity using positive contrast computed tomography canalography.

Introduction: The assessment of the integrity of the tympanic membrane (TM) can be a diagnostic challenge in patients with otitis externa and/or otitis media (OM) under an otoscopic examination. In computed tomography (CT), the TM is not always visualized. However, a positive contrast canalography using conventional radiography has been previously described to evaluate the TM integrity. Objective: This single-center study aimed to describe the positive contrast canalography technique in CT and its usefulness in identifying TM integrity in 11 dogs. Methods: Dogs with clinical signs of ear disease underwent CT canalography following a systematic protocol. Result: The presence of contrast medium and contrast homogeneity within the tympanic cavity was assessed, confirming TM rupture when contrast medium was present in the tympanic cavity. CT canalography was performed in 16 ears, and in 7 of the 16 ears (44%), there was a contrast in the tympanic cavity, confirming TM rupture (positive CT canalography result). In two of the seven cases (29%), rupture of the TM was identified in both otoscopic and CT canalography. In the remaining five of the seven (71%) positive CT canalography results, tympanic membrane rupture was identified only by CT canalography. Discussion: In conclusion, a positive contrast CT canalography is a complementary and safe technique to assess TM integrity, with a potentially higher sensitivity than otoscopic examination for the diagnosis of TM rupture in dogs.

Comparison of surrogate indices for insulin sensitivity with parameters of the intravenous glucose tolerance test in early lactation dairy cattle.

The aim of this study was to investigate the correlation between different surrogate indices and parameters of the intravenous glucose tolerance test (IVGTT) in dairy cows at the start of their lactation. Ten dairy cows underwent IVGTT on Days 3 to 7 after calving. Areas under the curve during the 90 min after infusion, peak and nadir concentrations, elimination rates, and times to reach half-maximal and basal concentrations for glucose, insulin, nonesterified fatty acids, and ß-hydroxybutyrate were calculated. Surrogate indices were computed using the average of the IVGTT basal samples, and their correlation with the IVGTT parameters studied through the Spearman's rank test. No statistically significant or strong correlation coefficients (P > 0.05; |ρ| < 0.50) were observed between the insulin sensitivity measures derived from the IVGTT and any of the surrogate indices. Therefore, these results support that the assessment of insulin sensitivity in early lactation cattle cannot rely on the calculation of surrogate indices in just a blood sample, and the more laborious tests (ie, hyperinsulinemic euglycemic clamp test or IVGTT) should be employed to predict the sensitivity of the peripheral tissues to insulin accurately.

Effect of Parenteral Antioxidant Supplementation During the Dry Period on Postpartum Glucose Tolerance in Dairy Cows.

BACKGROUND: Exacerbated postparturient insulin resistance (IR) has been associated with several pathologic conditions in dairy cattle. Oxidative stress (OS) plays a causative role in IR in humans, and an association, but not direct relationship, between OS and IR recently has been reported in transition dairy cattle. HYPOTHESIS: Supplementation with antioxidants shortly before calving improves glucose tolerance after parturition in dairy cattle. ANIMALS: Ten late-pregnant Holstein cows entering their 2nd to 5th lactation. METHODS: Randomized placebo-controlled trial: 15 ± 2 days before expected calving, the treatment group received an injection of DL-alpha-tocopheryl acetate at a dosage of 6 mg/kg body weight (BW) and 0.06 mg/kg BW of sodium selenite, and the control group was injected with isotonic saline. During the first week after calving, both groups underwent glucose tolerance testing (0.25 g glucose/kg BW). Commercial assays were used to quantify the concentrations of glucose, insulin, nonesterified fatty acids (NEFA), beta-hydroxybutyrate, and markers of redox status in blood. Data were analyzed using the Mann-Whitney U-test (α = 0.05). RESULTS: Supplemented cows showed a lower risk for OS, as reflected by a lower OS index (P = .036), different areas under the curve for the concentrations of glucose (P < .01), insulin (P = .043), and NEFA (P = .041), more rapid elimination rates (P = .080, <.01 and .047 respectively), and shorter half-lives (P = .040, <.01 and .032) of these metabolites. CONCLUSIONS AND CLINICAL IMPORTANCE: Supplementation with antioxidants before calving resulted in greater insulin sensitivity after calving, thereby suggesting the role of OS in the development of IR in cattle and the potential benefits of antioxidant supplementation in minimizing the consequences of negative energy balance.