OBJECTIVE To determine the effect of oral administration of gabapentin (20 mg/kg) on the minimum alveolar concentration (MAC) of isoflurane in dogs. ANIMALS 6 healthy adult dogs (3 males and 3 females with a mean ± SD body weight of 24.8 ± 1.3 kg). PROCEDURES Each dog was anesthetized twice. Dogs were initially assigned to 1 of 2 treatments (gabapentin [20 mg/kg, PO] followed 2 hours later by anesthesia maintained with isoflurane or anesthesia maintained with isoflurane alone). A minimum of 7 days later, dogs received the other treatment. The MAC of isoflurane was determined by use of an iterative bracketing technique with stimulating electrodes placed in the maxillary buccal mucosa. Hemodynamic variables and vital parameters were recorded at the lowest end-tidal isoflurane concentration at which dogs did not respond to the stimulus. Effect of treatment on outcome variables was analyzed by use of a paired t test. RESULTS Mean ± SD MAC of isoflurane was significantly lower when dogs received gabapentin and isoflurane (0.71 ± 0.12%) than when dogs received isoflurane alone (0.91 ± 0.26%). Mean reduction in MAC of isoflurane was 20 ± 14%. Hemodynamic variables did not differ significantly between treatments. Mean time to extubation was significantly less when dogs received gabapentin and isoflurane (6 ± 4 minutes) than when dogs received isoflurane alone (23 ± 15 minutes). CONCLUSIONS AND CLINICAL RELEVANCE Oral administration of gabapentin 2 hours before anesthesia maintained with isoflurane had a MAC-sparing effect with no effect on hemodynamic variables or vital parameters of dogs.

OBJECTIVE To evaluate the effects of injectable dexmedetomidine-ketamine-midazolam (DKM) and isoflurane inhalation (ISO) anesthetic protocols on selected ocular variables in captive black-tailed prairie dogs (Cynomys ludovicianus; BTPDs). ANIMALS 9 zoo-kept BTPDs. PROCEDURES The BTPDs received dexmedetomidine hydrochloride (0.25 mg/kg, IM), ketamine hydrochloride (40 mg/kg, IM), and midazolam hydrochloride (1.5 mg/kg, IM) or inhalation of isoflurane and oxygen in a randomized complete crossover design (2-day interval between anesthetic episodes). Pupil size, globe position, tear production, and intraocular pressure measurements were recorded at 5, 30, and 45 minutes after induction of anesthesia. For each BTPD, a phenol red thread test was performed in one randomly selected eye and a modified Schirmer tear test I was performed in the other eye. Intraocular pressure was measured by rebound tonometry. RESULTS Compared with findings for the DKM protocol, pupil size was smaller at all time points when the BTPDs underwent the ISO protocol. Globe position remained central during anesthesia with the DKM protocol, whereas it varied among central, ventromedial, and ventrolateral positions during anesthesia with the ISO protocol. Tear production and intraocular pressure decreased significantly over time when the BTPDs underwent either protocol. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that ophthalmic examination findings for anesthetized BTPDs can be influenced by the anesthetic protocol used. The DKM protocol may result in more consistent pupil size and globe position, compared with that achieved by use of the ISO protocol. Tear production and intraocular pressure measurements should be conducted promptly after induction of anesthesia to avoid the effect of anesthetic episode duration on these variables.

OBJECTIVE To evaluate erythema and number of CFUs on the skin of dogs with hair clipped by use of 2 sizes of clipper blades. ANIMALS 67 client-owned dogs receiving an epidural. PROCEDURES Hair was clipped with a No. 10 blade (approx hair length, 1.5 mm) on one half and a No. 40 blade (approx hair length, 0.25 mm) on the other half of each epidural site. Skin was surgically scrubbed with 2% chlorhexidine gluconate and 70% isopropyl alcohol. Samples were obtained immediately after clipping, after skin was scrubbed, and again 24 hours after clipping. Number of CFUs for both sides of the clipped areas, types of microorganisms, and growth on MacConkey agar were evaluated every 24 hours for 72 hours. Colonies were evaluated for bacterial morphology and Gram stain characteristics. Sites were evaluated 24 hours after clipping for evidence of erythema. RESULTS 24 hours after hair was clipped, there was a significantly higher incidence of erythema and higher number of Micrococcaceae bacteria for the side clipped with the No. 40 blade than the side clipped with the No. 10 blade. Number of CFUs did not differ significantly between size of clipper blades. CONCLUSIONS AND CLINICAL RELEVANCE Clipping hair with a No. 40 blade resulted in a significant increase in the incidence of erythema and higher number of Micrococcaceae bacteria, compared with results for clipping with a No. 10 blade. These results supported use of a No. 10 clipper blade to prevent erythema and reduce variation in the skin microbiome.

OBJECTIVE To assess recording accuracy of right atrial and ventricular depolarization during 12-lead ECG when precordial lead V1 was positioned at each of 5 locations on the thorax of dogs with various thoracic conformations. ANIMALS 60 healthy client-owned dogs. PROCEDURES 20 dogs were allocated to each of 3 groups (brachymorphic, mesomorphic, or dolichomorphic) on the basis of thoracic conformation. Each dog remained unsedated and was positioned in right lateral recumbency for a series of five 12-lead surface ECGs, with V1 located adjacent to the sternum in the fifth intercostal space (ICS; control), at the costochondral junction (CCJ) of the right first ICS (1st-R), at the CCJ of the right third ICS, at the right third ICS where the thorax was the widest, and at the CCJ of the left first ICS. Electrocardiographic variables were compared among the 5 ECG tracings. RESULTS When V1 was at the control location, the P wave was positive for all dogs; however, consistent recording of right atrial and ventricular depolarization (ie, R wave-to-S wave ratio [R/S] < 1) occurred more frequently for brachymorphic dogs (16/20) than for dolichomorphic (7/20) and mesomorphic (6/20) dogs. When V1 was at the 1st-R location, the P wave was negative for most dogs, and R/S was < 1 for the majority of dogs in the brachymorphic (19/20), mesomorphic (17/20), and dolichomorphic (16/20) groups. The median R/S for V1 at the 1st-R location was significantly lower than that for the other 4 V1 locations. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that placement of V1 at the 1st-R location provided correct evaluation of right atrial and ventricular depolarization in most dogs regardless of thoracic conformation.

OBJECTIVE To assess feasibility of the use of a dynamic viscoelastic coagulometer on chicken blood and compare coagulation variables for fresh whole blood and sodium citrate–preserved whole blood as well as effects of 3 coagulation activators on blood from chickens. SAMPLE Blood samples from 30 hens. PROCEDURES Chickens were allowed to rest undisturbed for 1 hour. A blood sample was collected from an ulnar vein; 1.4 mL was analyzed immediately, and 1.8 mL was mixed with sodium citrate and subsequently recalcified and analyzed. A separate coagulation activator (glass beads, kaolin clay, or tissue factor) was in each of the 2 channels of the analyzer. Chickens were allowed a 1-hour rest period, and another blood sample was collected from the contralateral ulnar vein; it was processed in the same manner as for the first sample, except both channels of the analyzer contained the same coagulation activator. RESULTS Compared with fresh samples, citrated samples had higher values for activated clotting time and platelet function and lower clotting rates. Intra-assay coefficients of variation of coagulation profiles for citrated samples were markedly greater than the limit of 10%, whereas values for fresh samples were close to or < 10%. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that use of a dynamic viscoelastic coagulometer on chicken blood was feasible and that analysis of fresh whole blood from healthy chickens provided results with less variability than did analysis of citrated blood. Samples preserved with sodium citrate were associated with significant relative hypocoagulability, compared with results for fresh blood.

OBJECTIVE To determine whether passage of whole blood through a microaggregate filter by use of a syringe pump would damage canine erythrocytes. SAMPLE Blood samples obtained from 8 healthy client-owned dogs. PROCEDURES Whole blood was passed through a standard microaggregate filter by use of a syringe pump at 3 standard administration rates (12.5, 25, and 50 mL/h). Prefilter and postfilter blood samples were collected at the beginning and end of a simulated transfusion. Variables measured at each time point included erythrocyte osmotic fragility, mean corpuscular fragility, RBC count, hemoglobin concentration, RBC distribution width, and RBC morphology. In-line pressure when blood passed through the microaggregate filter was measured continuously throughout the simulated transfusion. After the simulated transfusion was completed, filters were visually analyzed by use of scanning electron microscopy. RESULTS Regardless of administration rate, there was no significant difference in mean corpuscular fragility, RBC count, hemoglobin concentration, or RBC distribution width between prefilter and postfilter samples. Additionally, there were no differences in in-line pressure during the simulated transfusion among administration rates. Echinocytes were the erythrocyte morphological abnormality most commonly observed at the end of the transfusion at administration rates of 12.5 and 25 mL/h. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that regardless of the administration rate, the microaggregate filter did not alter fragility of canine RBCs, but may have altered the morphology. It appeared that the microaggregate filter would not contribute to substantial RBC damage for transfusions performed with a syringe pump.

OBJECTIVE To determine whether the degree of CT attenuation of muscle would differ between healthy old and young dogs. ANIMALS 10 healthy old (> 8 years old) and 9 healthy young (1 to 5 years old) Labrador Retrievers with a body condition score of 5 or 6 on a 9-point scale. PROCEDURES CT was performed with the dogs mildly sedated. A freehand closed polygon tool was used to define the outer margin of the left epaxial muscles on each transverse image obtained from the cranial to caudal endplates of T13. The CT attenuation values from every voxel from within these regions of interest were exported from DICOM software as a single dataset in an extensible markup language file. From these data, mean CT attenuation values were calculated for each dog and these mean values were compared between age groups. RESULTS Mean CT attenuation values for the epaxial muscles were significantly lower in old dogs than in young dogs. A significant negative correlation (r = –0.74) was identified between mean CT attenuation values and dog age. CONCLUSIONS AND CLINICAL RELEVANCE In addition to loss of skeletal muscle mass, low muscle CT attenuation values suggested that the old dogs in this study also had greater muscle fat content than did young dogs. Additional studies are warranted to evaluate qualitative and quantitative muscle changes in old dogs.

OBJECTIVE To evaluate use of flunixin meglumine as a treatment to postpone ovulation in mares, mare fertility after flunixin meglumine treatment during estrous cycles, and effects of flunixin meglumine on function of the corpus luteum after ovulation. ANIMALS 13 healthy mares. PROCEDURES A single-blinded, placebo-controlled, crossover study was conducted. Flunixin meglumine (1.1 mg/kg, IV, q 24 h) or lactated Ringer solution (placebo treatment) was administered for 2 days to mares with a dominant follicle (≥ 35 mm in diameter) and behavioral signs of estrus. Mares then were bred by artificial insemination. Number of days to ovulation from initial detection of a follicle ≥ 30 mm in diameter, uterine edema score, and pregnancy were determined by ultrasonography; the examiner was unaware of the treatment of each mare. Serum progesterone concentrations were evaluated 5 and 12 days after ovulation by use of radioimmunoassay. RESULTS Data were available for 45 estrus cycles of the 13 mares. Number of days to ovulation from initial detection of a follicle ≥ 30 mm was not significantly affected by administration of flunixin meglumine versus the placebo. Per-cycle pregnancy rate was not significantly different between flunixin meglumine (20/24 [83%] breedings) and the placebo (13/19 [68%] breedings). Flunixin meglumine did not significantly affect behavioral signs of estrus, uterine edema, or serum progesterone concentrations. CONCLUSIONS AND CLINICAL RELEVANCE Findings did not support the use of flunixin meglumine to postpone ovulation in mares.

OBJECTIVE To determine the mean diameter of the main portal vein (PV) in healthy dogs by use of CT angiography, identify any associations between PV diameter and certain dog characteristics, and validate a clinically valuable ratio for quantifying the size of the PV. ANIMALS 100 dogs with no hepatic, cardiac, or vascular anomalies that underwent abdominal CT angiography. PROCEDURES Diameters of the main PV, abdominal aorta (Ao), and caudal vena cava (CVC) were measured by 2 observers at a defined location on postcontrast CT angiographic images in axial, sagittal, and transverse planes. Dog characteristics were evaluated for associations with PV diameter, and a PV:Ao diameter ratio was calculated. Intraclass correlations were calculated to assess intra- and interobserver agreement in vessel diameter measurements. RESULTS Mean diameter values were 7.9 mm (range, 4.1 to 14.8 mm) for the PV, 8.9 mm (range, 3.7 to 13.7 mm) for the Ao, and 11.4 mm (range, 4.4 to 22.5 mm) for the CVC. The PV:Ao diameter ratio was 0.91 mm. The PV diameter was significantly associated with dog body weight but not with dog age, sex, or neuter status. Intra- and interobserver reliabilities for measurements of all 3 vessels were considered excellent (intraclass correlation coefficients > 0.85). CONCLUSIONS AND CLINICAL RELEVANCE Findings indicated that the PV:Ao diameter ratio was a repeatable measurement that may be useful for evaluating the size of the portal vasculature in dogs and possibly for distinguishing healthy PVs from abnormal PVs in dogs with hepatic vascular anomalies.

OBJECTIVE To determine whether Mycobacterium bovis remains viable in ensiled forages. SAMPLE Alfalfa, mixed mostly grass, and corn silages. PROCEDURES For each of 10 sampling days, six 250-g replicate samples of each feedstuff were created and placed in a film pouch that could be vacuum sealed to simulate the ensiling process. Within each set of replicate samples, 4 were inoculated with 10 mL of mycobacterial liquid culture medium containing viable M bovis and 2 were inoculated with 10 mL of sterile mycobacterial liquid culture medium (controls) on day 0. Pouches were vacuum sealed and stored in the dark at room temperature. On the designated sampling day, 1 control pouch was submitted for forage analysis, and the other pouches were opened, and forage samples were obtained for M bovis culture and analysis with a PCR assay immediately and 24 hours later. RESULTS None of the control samples had positive M bovis culture or PCR assay results. Among M bovis-inoculated samples, the organism was not cultured from alfalfa and corn silage for > 2 days but was cultured from mixed mostly grass silage for 28 days after inoculation and ensiling initiation. Mycobacterium bovis DNA was detected by PCR assay in samples of all 3 feedstuffs throughout the 112-day observation period. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that properly ensiled forages would be an unlikely source for M bovis transmission to cattle. Further research is necessary to determine whether ensiling kills M bovis or forces it to become dormant and, if the latter, elucidate the conditions that cause it to revert to an infectious state.