OBJECTIVE To quantify the effect of time and recumbency on CT measurements of lung volume and attenuation in healthy cats under general anesthesia. ANIMALS 8 healthy research cats. PROCEDURES Anesthetized cats were positioned in sternal recumbency for 20 minutes and then in left, right, and left lateral recumbency (40 minutes/position). Expiratory helical CT scan of the thorax was performed at 0 and 20 minutes in sternal recumbency and at 0, 5, 10, 20, 30, and 40 minutes in each lateral recumbent position. For each lung, CT measurements of lung volume and attenuation and the extent of lung areas that were hyperaerated (−1,000 to −901 Hounsfield units [HU]), normoaerated (−900 to −501 HU), poorly aerated (−500 to −101 HU), or nonaerated (−100 to +100 HU [indicative of atelectasis]) were determined with a semiautomatic threshold-based technique. A restricted maximum likelihood analysis was performed. RESULTS In lateral recumbency, the dependent lung had significantly greater attenuation and a lower volume than the nondependent lung. Within the dependent lung, there was a significantly higher percentage of poorly aerated lung tissue, compared with that in the nondependent lung. These changes were detected immediately after positioning the cats in lateral recumbency and remained static with no further significant time-related change. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that once anesthetized healthy cats were positioned in lateral recumbency, the dependent lung lobes underwent a rapid reduction in lung volume and increase in lung attenuation that did not progress over time, predominantly attributable to an increase in poorly aerated lung tissue.

OBJECTIVE To evaluate effects of blood contamination on dipstick results, specific gravity (SG), and urine protein-to-urine creatinine ratio (UPCR) for urine samples from dogs and cats. SAMPLE Urine samples collected from 279 dogs and 120 cats. PROCEDURES Urine pools were made for each species (dogs [n = 60] and cats [30]). Blood was added to an aliquot of a pool, and serial dilutions were prepared with the remaining urine. Color and dipstick variables were recorded, and SG and UPCR were measured. For cats, 1 set of pools was used; for dogs, 2 sets were used. Comparisons were made between undiluted urine and spiked urine samples for individual colors. Repeated-measures ANOVA on ranks was used to compare dipstick scores and UPCR results; χ2 tests were used to compare proteinuria categorizations (nonproteinuric, borderline, or proteinuric). RESULTS Any blood in the urine resulted in significantly increased dipstick scores for blood. In both species, scores for bilirubin and ketones, pH, and SG were affected by visible blood contamination. No significant difference for the dipstick protein reagent results was evident until a sample was visibly hematuric. The UPCR was significantly increased in dark yellow samples of both species. Proteinuria categorizations differed significantly between undiluted urine and urine of all colors, except light yellow. CONCLUSIONS AND CLINICAL RELEVANCE Any degree of blood contamination affected results of dipstick analysis. Effects depended on urine color and the variable measured. Microscopic blood contamination may affect the UPCR; thus, blood contamination may be a differential diagnosis for proteinuria in yellow urine samples.

OBJECTIVE To identify the genetic cause for congenital photosensitivity and hyperbilirubinemia (CPH) in Southdown sheep. ANIMALS 73 Southdown sheep from a CPH research flock and 48 sheep of various breeds from commercial flocks without CPH. PROCEDURES Whole-genome sequencing was performed for a phenotypically normal Southdown sheep heterozygous for CPH. Heterozygous variants within Slco1b3 coding exons were identified, and exons that contained candidate mutations were amplified by PCR assay methods for Sanger sequencing. Blood samples from the other 72 Southdown sheep of the CPH research flock were used to determine plasma direct and indirect bilirubin concentrations. Southdown sheep with a plasma total bilirubin concentration < 0.3 mg/dL were classified as controls, and those with a total bilirubin concentration ≥ 0.3 mg/dL and signs of photosensitivity were classified as mutants. Sanger sequencing was used to determine the Slco1b3 genotype for all sheep. Genotypes were compared between mutants and controls of the CPH research flock and among all sheep. Protein homology was measured across 8 species to detect evolutionary conservation of Slco1b. RESULTS A nonsynonymous mutation at ovine Chr3:193,691,195, which generated a glycine-to-arginine amino acid change within the predicted Slco1b3 protein, was significantly associated with hyperbilirubinemia and predicted to be deleterious. That amino acid was conserved across 7 other mammalian species. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested a nonsynonymous mutation in Slco1b3 causes CPH in Southdown sheep. This disease appears to be similar to Rotor syndrome in humans. Sheep with CPH might be useful animals for Rotor syndrome research.

Using lung tissues separated from 12-day-old chicken embryos, we attempted to obtain a novel population of stem cells, namely, chicken lung-derived mesenchymal stem cells (LMSCs), which exhibit spindle-like morphology. The results of colony-forming assay and population doubling assay demonstrated that LMSCs had enormous colony-forming, self-renewal, and proliferative potential. When appropriately induced, LMSCs could differentiate into osteoblasts, adypocytes, chondrocytes, and neurons; in other words, LMSCs had cross-embryonic layer differentiation potential under corresponding induction conditions. Aside from colony-forming, self-renewal, and multilineage differentiation capabilities, LMSCs were characterized by specific cell phenotypes. The results of immunohistochemistry and flow cytometry demonstrated that LMSCs consistently expressed OCT-4 - a specific gene marker expressed in pluripotent stem cells - and markers associated with MSCs such as CD29, CD73, CD90, and CD105. However, LMSCs lacked hematopoietic cell surface molecules such as CD34 and CD45. Primary LMSCs could be subcultured to passage 24 at most in vitro and karyotype analysis demonstrated that LMSCs possessed genomic stability. These unique characteristics were consistent with the characteristics of MSCs, which had been isolated from other tissues. This provides a foundation for LMSCs as a promising avenue for cellular transplantation therapy, regenerative medicine, and tissue engineering.

OBJECTIVE To evaluate cardiopulmonary, sedative, and antinociceptive effects of dexmedetomidine combined with commonly administered opioids in dogs. ANIMALS 8 healthy Beagles. PROCEDURES Dogs were sedated by IM administration of each of 7 treatments. Treatments comprised dexmedetomidine (0.01 mg/kg; Dex) and the same dose of dexmedetomidine plus butorphanol (0.15 mg/kg; Dex-But), meperidine (5 mg/kg; Dex-Mep), methadone (0.5 mg/kg; Dex-Meth), morphine (0.5 mg/kg; Dex-Mor), nalbuphine (0.5 mg/kg; Dex-Nal), or tramadol (5 mg/kg; Dex-Tram). Cardiorespiratory and arterial blood gas variables and sedative and antinociceptive scores were measured before drug injection (time 0; baseline) and at 15-minute intervals for 120 minutes. RESULTS Heart rate was reduced at all time points after injection of Dex-But, Dex-Mep, Dex-Meth, and Dex-Mor treatments. There was a significant reduction of mean arterial blood pressure for Dex-But, Dex-Mep, and Dex-Mor treatments at all time points, compared with baseline. There was a significant decrease in respiratory rate, compared with the baseline value, for Dex, Dex-But, Dex-Meth, and Dex-Tram treatments from 15 to 120 minutes. A significant decrease in arterial blood pH was detected from baseline to 120 minutes for all treatments, with differences among Dex, Dex-Mep, and Dex-Mor. Reduction in Pao2 was greater for the Dex-Mep treatment than for the other treatments. The highest sedation scores were detected for Dex-Mep and Dex-Meth treatments. Antinociceptive effects were superior for Dex-But, Dex-Meth, Dex-Mor, and Dex-Nal treatments. CONCLUSIONS AND CLINICAL RELEVANCE Drug combinations caused similar cardiorespiratory changes, with greater sedative effects for Dex-Mep and Dex-Meth and superior antinociceptive effects for Dex-But, Dex-Meth, Dex-Mor, and Dex-Nal.

OBJECTIVE To determine brain region affinity for and retention of gadolinium in dogs after administration of gadodiamide and whether formalin fixation affects quantification. ANIMALS 14 healthy dogs. PROCEDURES 13 dogs received gadodiamide (range, 0.006 to 0.1 mmol/kg, IV); 1 control dog received a placebo. Dogs received gadodiamide 3 to 7 days (n = 8) or 9 hours (5) before euthanasia and sample collection. Brain regions were analyzed with inductively coupled mass spectrometry (ICP-MS) and transmission electron microscopy. Associations between dose, time to euthanasia, and gadolinium retention quantities (before and after fixation in 5 dogs) were evaluated. RESULTS Gadolinium retention was seen in all brain regions at all doses, except for the control dog. Exposure 3 to 7 days before euthanasia resulted in 1.7 to 162.5 ng of gadolinium/g of brain tissue (dose-dependent effect), with cerebellum, parietal lobe, and brainstem affinity. Exposure 9 hours before euthanasia resulted in 67.3 to 1,216.4 ng of gadolinium/g of brain tissue without dose dependency. Transmission electron microscopy revealed gadolinium in examined tissues. Fixation did not affect quantification in samples immersed for up to 69 days. CONCLUSIONS AND CLINICAL RELEVANCE Gadodiamide exposure resulted in gadolinium retention in the brain of healthy dogs. Cerebellum, parietal lobe, and brainstem affinity was detected with dose dependency only in dogs exposed 3 to 7 days before euthanasia. Fixation had no effect on quantification when tissues were immersed for up to 69 days. Physiologic mechanisms for gadolinium retention remained unclear. The importance of gadolinium retention requires further investigation.

OBJECTIVE To determine whether target values for pharmacokinetic-pharmacodynamic (PK-PD) indices against selected canine pathogens were achievable for pradofloxacin in various canine fluids and leukocytes. ANIMALS 8 healthy adult hounds (experiments 1 and 2) and 6 healthy adult dogs (experiment 3). PROCEDURES In 3 experiments, pradofloxacin (3, 6, or 12 mg/kg) and enrofloxacin (5 or 10 mg/kg) were orally administered once a day for 5 days, and blood, interstitial fluid (ISF), and other fluid samples were collected at various points. Sample drug concentrations were measured, and noncompartmental pharmacokinetic analysis was performed; then, PK-PD indices (ratios between maximum observed concentration [Cmax] and minimum inhibitory or mutant prevention concentrations) were determined for 7 bacterial species. RESULTS PK-PD values for pradofloxacin at 3 mg/kg were approximately 5 times as high in leukocyte versus plasma and were lowest in CSF, synovial fluid, and aqueous humor. No significant differences were noted between serum and ISF. Value ratios for serum versus other body fluids were numerically higher for pradofloxacin (vs enrofloxacin) for all fluid types except CSF and aqueous humor. Target PK-PD values were exceeded for pradofloxacin against all 7 bacterial species in leukocytes and against all species except Bacteroides spp in serum and ISF. Enrofloxacin achieved the target Cmax-to-minimum inhibitory concentration ratio against Pasteurella multocida in serum, ISF, and leukocytes and for Staphylococcus pseudintermedius in serum and leukocytes. A Cmax-to-mutant prevention concentration ratio ≥ 1 against Eschericha coli was achieved for pradofloxacin at 6 mg/kg. CONCLUSIONS AND CLINICAL RELEVANCE These findings supported once-daily oral administration of pradofloxacin to dogs at the currently recommended dose (7.5 mg/kg).

OBJECTIVE To compare dialysate sodium concentration and patient plasma sodium concentration of dogs during intermittent hemodialysis treatments. SAMPLE 211 intermittent hemodialysis treatments performed on 40 client-owned dogs for the management of dialysis-dependent uremia. PROCEDURES Medical records were reviewed to determine the plasma sodium concentration of each dog before and after routine hemodialysis treatments. Associations between detected changes in plasma sodium concentration and dialysate sodium concentration were evaluated by use of Spearman rank correlations and linear regression analysis. RESULTS Significant linear correlations were found between the dialysate sodium concentration and patient sodium concentration. The starting dialysate-to-patient sodium gradient was associated with the strongest correlation to the change in patient sodium concentration at the end of the dialysis session. Modest correlations existed between the dialysate sodium concentration and postdialysis patient sodium concentration as well as between the predialysis dialysate-to-patient sodium gradient and postdialysis dialysate-to-patient sodium gradient. CONCLUSIONS AND CLINICAL RELEVANCE The dialysate sodium concentration was correlated with the patient sodium concentration in dogs, and the dialysate-to-patient sodium gradient could be used to further refine this association to predict the postdialysis patient sodium concentration and potentially manage dysnatremia during hemodialysis. Prospective studies should be performed to determine how these associations can be used to correct aberrations as well as to avoid unwanted alterations in patient sodium concentrations.

OBJECTIVE To determine the influence of various neck positions on cervical vertebral radiographic measurements in horses. ANIMALS 18 client-owned horses examined for lameness but free of cervical disease. PROCEDURES Laterolateral radiographs of the cervical vertebrae from C1 through T1 were acquired for each horse in 3 neck positions (low, neutral, and high). Minimum sagittal diameter, intravertebral sagittal diameter (intra-VSD) ratio, inter-VSD ratio, length of the articular processes joint ratio, vertebral alignment angle, and vertebral fossa angle were measured at each segment in each neck position. Values for the high and low positions were compared with those for the neutral position. RESULTS No significant differences from neutral position values were identified for minimum sagittal diameter, intra-VSD ratio, and vertebral fossa angle as measured in low and high neck positions. Compared with results in the neutral position, the high position resulted in a greater vertebral alignment angle at C3–4 and inter-VSD ratio at C4–5 and a lower length of the articular processes joint ratio at C2–3, C3–4, and C4–5; the low position resulted in a lower vertebral alignment angle at C4–5. However, all observed differences were small. CONCLUSIONS AND CLINICAL RELEVANCE Neck position influenced some radiographic measurements of the cervical vertebrae in horses free of cervical disease. However, because several of these measurements were not or were only minimally affected by neck position, some latitude in neck position may be possible without concern about substantially affecting radiographic measurements in this region.

OBJECTIVE To characterize the fecal microbiota of horses and to investigate alterations in that microbiota on the basis of sample collection site (rectum vs stall floor), sample location within the fecal ball (center vs surface), and duration of environmental exposure (collection time). ANIMALS 6 healthy adult mixed-breed mares. PROCEDURES From each horse, feces were collected from the rectum and placed on a straw-bedded stall floor. A fecal ball was selected for analysis immediately after removal from the rectum and at 0 (immediately), 2, 6, 12, and 24 hours after placement on the stall floor. Approximately 250 mg of feces was extracted from the surface and center of each fecal ball, and genomic DNA was extracted, purified, amplified for the V1-V2 hypervariable region of the 16S rDNA gene, and analyzed with a bioinformatics pipeline. RESULTS The fecal microbiota was unique for each horse. Bacterial community composition varied significantly between center and surface fecal samples but was not affected by collection time. Bacterial community composition varied rapidly for surface fecal samples. Individual bacterial taxa were significantly associated with both sample location and collection time but remained fairly stable for up to 6 hours for center fecal samples. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that, for horses, fecal samples for microbiota analysis should be extracted from the center of fecal balls collected within 6 hours after defecation. Samples obtained up to 24 hours after defecation can be analyzed with the realization that some bacterial populations may deviate from those immediately after defecation.