OBJECTIVE To compare ultracentrifugation, precipitation, and membrane affinity chromatography methods for isolation of extracellular vesicles (EVs) from canine plasma samples and to identify suitable reference genes for incorporation into a quantitative reverse transcription PCR assay of microRNA expression in plasma EVs of healthy dogs. ANIMALS 6 healthy Beagles. PROCEDURES Plasma samples were obtained from each dog, and EVs were isolated from 0.3 mL of these samples via ultracentrifugation, precipitation, and membrane-affinity chromatographic methods. Nanoparticle tracking analysis was performed to determine the concentration and size distribution of EVs isolated by the ultracentrifugation method. Expression levels (cycle threshold values) of 4 microRNAs (let-7a, miR-16, miR-26a, and miR-103) were then compared by means of quantitative reverse transcription PCR assay. Three statistical programs were used to identify the microRNAs most suitable for use as reference genes. RESULTS Results indicated that ultracentrifugation was the most stable of all 3 methods for isolating microRNAs from 0.3 mL of plasma. Nanoparticle tracking revealed that EV samples obtained by the ultracentrifugation method contained a mean ± SD of approximately 1.59 × 10(10) vesicles/mL ± 4.2 × 10(8) vesicles/mL. Of the 4 microRNAs in plasma EVs isolated by ultracentrifugation, miR-103 was the most stable. CONCLUSIONS AND CLINICAL RELEVANCE The ultracentrifugation method has potential as a stable method for isolating EVs from canine plasma samples with a high recovery rate, and miR-103 may provide the most stable reference gene for normalizing microRNA expression data pertaining to plasma EVs isolated by ultracentrifugation.

OBJECTIVE To evaluate the clinicopathologic, hemodynamic, and echocardiographic effects of short-term administration of anti-inflammatory dosages of prednisolone to systemically normal cats. ANIMALS 10 cats with allergic dermatitis and 10 healthy control cats. PROCEDURES Cats with allergic dermatitis were randomly allocated to 2 groups and received 2 dosages of prednisolone (1 and 2 mg/kg/d, PO, for 7 days) in a crossover design followed by 9-day tapering and 14-day washout periods. Each prednisolone-treated cat was matched to a healthy control cat on the basis of sex, neuter status, age (± 1 year), and body weight (± 10%). Control cats received no treatment during the 35-day observation period. Clinicopathologic, echocardiographic, and hemodynamic variables were measured at baseline (day 0) and predetermined times during and after prednisolone administration and compared within and between the 2 treatment groups. RESULTS Prednisolone-treated cats had expected clinicopathologic alterations (mild increases in neutrophil and monocyte counts and serum concentrations of albumin, cholesterol, and triglycerides) but systolic arterial blood pressure; blood glucose, serum potassium, and cardiac biomarker concentrations; urinary sodium excretion; and echocardiographic variables did not differ significantly from baseline at any time. Statistically significant, albeit clinically irrelevant, increases in blood glucose and N-terminal pro-B-type natriuretic peptide concentrations were observed between baseline and the prednisolone pharmacokinetic steady state (7 days after initiation) only when the 2-mg/kg dosage was administered. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated short-term oral administration of anti-inflammatory dosages of prednisolone did not cause relevant hemodynamic, echocardiographic, or diabetogenic effects in systemically normal cats with allergic dermatitis.

OBJECTIVE To evaluate recovery of limb function by use of gait force analysis after tibial plateau leveling osteotomy (TPLO) in dogs with unilateral cranial cruciate ligament (CrCL) rupture. ANIMALS 19 dogs with unilateral CrCL rupture treated with TPLO. PROCEDURES Force plate gait analysis was performed before and 1, 2, 4, and 7 months after TPLO. Ground reaction forces (GRFs; which comprised peak vertical force [PVF], vertical impulse [VI], peak braking force, braking impulse, peak propulsion force [PPF], and propulsion impulse), time to switching from braking to propulsion, and vector magnitude at PVF in the forelimbs and hind limbs were evaluated. RESULTS GRFs in the affected hind limb were significantly lower than in the contralateral hind limb before TPLO. These variables, except for PPF, were not significantly different 7 months after TPLO. Time to the switching point in the affected hind limb was significantly less from before to 2 months after TPLO. Vector magnitude at PVF had a similar pattern as PVF and VI during the recovery process. The PVF in the ipsilateral forelimb was significantly higher than in the contralateral forelimb before TPLO. CONCLUSIONS AND CLINICAL RELEVANCE A similar pattern was detected between PVF or VI and craniocaudal force during recovery of dogs that underwent TPLO. Rupture of he CrCl resulted in a decrease in GRFs in the affected hind limb as well as in the switching point and PVF of limbs. However, weight distribution for the craniocaudal force was normalized before PVF or VI. Vector magnitude at PVF might be effectively evaluated by combining vertical force and craniocaudal force.

OBJECTIVE To compare results of a commercially available device for oscillometrically measured blood pressure (OBP) with invasively measured blood pressure (IBP) in awake and anesthetized dogs. ANIMALS 19 adult dogs (mean ± SD body weight, 17.8 ± 7.5 kg). PROCEDURES Blood pressures were measured in dogs while they were awake and anesthetized with isoflurane. The OBP was recorded on a thoracic limb, and IBP was simultaneously recorded from the median caudal artery. Agreement between OBP and IBP was evaluated with the Bland-Altman method. Guidelines of the American College of Veterinary Internal Medicine (ACVIM) were used for validation of the oscillometric device. RESULTS In awake dogs, mean bias of the oscillometric device was −11.12 mm Hg (95% limits of agreement [LOA], −61.14 to 38.90 mm Hg) for systolic arterial blood pressure (SAP), 9.39 mm Hg (LOA, −28.26 to 47.04 mm Hg) for diastolic arterial blood pressure (DAP), and −0.85 mm Hg (LOA, −40.54 to 38.84 mm Hg) for mean arterial blood pressure (MAP). In anesthetized dogs, mean bias was −12.27 mm Hg (LOA, −47.36 to 22.82 mm Hg) for SAP, −3.92 mm Hg (LOA, −25.28 to 17.44 mm Hg) for DAP, and −7.89 mm Hg (LOA, −32.31 to 16.53 mm Hg) for MAP. The oscillometric device did not fulfill ACVIM guidelines for the validation of such devices. CONCLUSIONS AND CLINICAL RELEVANCE Agreement between OBP and IBP results for awake and anesthetized dogs was poor. The oscillometric blood pressure device did not fulfill ACVIM guidelines for validation. Therefore, clinical use of this device cannot be recommended.

OBJECTIVE To compare anesthetic effects of alfaxalone-ketamine-dexmedetomidine (AKD) and alfaxalone-butorphanol-midazolam (ABM) in naked mole-rats (Heterocephalus glaber). ANIMALS 20 naked mole-rats. PROCEDURES Naked mole-rats received AKD (alfaxalone, 2 mg/kg; ketamine, 20 mg/kg; and dexmedetomidine, 0.02 mg/kg; n = 10) or ABM (alfaxalone, 2 mg/kg; butorphanol, 2 mg/kg; and midazolam, 1 mg/kg; 9) IM; 1 animal was removed from the study. Atipamezole (I mg/kg) and flumazenil (0.1 mg/kg) were administered 40 minutes after anesthetic induction (defined as loss of the righting reflex) with AKD and ABM, respectively. Heart rate, respiratory rate, oxygen saturation, and reflexes were recorded every 5 minutes. RESULTS The ABM group had significantly longer median times for induction and recovery than the AKD group. Administration of ABM resulted in significantly lower respiratory rates than administration of AKD from time of anesthetic induction to 10 minutes after induction. Respiratory rate significantly decreased in the AKD group from I0 minutes after induction through the end of the anesthetic period but did not change over time in the ABM group. Males had higher respiratory rates in both groups. Loss of the righting reflex was still evident 40 minutes after induction in both groups. In the AKD group, all tested reflexes were absent from I0 to 40 minutes after induction; the ABM group had variable reflexes that recovered within individual animals over time. CONCLUSIONS AND CLINICAL RELEVANCE Both AKD and ABM provided effective immobilization in naked mole-rats, but AKD appeared to provide more consistent and deeper anesthesia, compared with administration of ABM.

OBJECTIVE To describe histologic changes in the temporomandibular joints (TMJs) of horses of various ages. SAMPLE 22 TMJs from cadavers of 11 horses. PROCEDURES Horses were categorized into 3 age groups (group 1, 2 to 10 years old [n = 3]; group 2, 11 to 20 years old [3]; and group 3, > 20 years old [5]). Each TMJ was sectioned into 5-mm slices, preserved in formalin, decalcified in formic acid, and routinely processed for histologic analysis. Joints were systematically assessed by use of previously described methods. Multilevel mixed-effects models were used to examine the data. RESULTS The number of changes was significantly fewer and degree of changes was significantly less within the TMJs of group 1 horses, compared with those of group 3 horses. Comparison among groups revealed that the combination of temporal and mandibular scores for group 1 was significantly lower than for groups 2 or 3. Disk score did not differ significantly between groups 1 and 2, but disk scores of groups 1 and 2 were significantly lower than the disk score of group 3. CONCLUSIONS AND CLINICAL RELEVANCE The assessed lesions were associated with osteoarthritis, and they accumulated in the TMJs as horses aged. In the absence of signs of pain manifested as changes in mastication, behavior, or performance, it would be difficult to determine the point at which accrued pathological changes represented the onset of clinically important osteoarthritis of the TMJs.

The primary objective of this study was to explore the variability of Streptococcus uberis (S. uberis) isolates by extracting multilocus sequence typing (MLST) data from whole-genome sequencing. The secondary objective was to determine the distribution of the phenotypic antimicrobial resistance (AMR) and the associated AMR genes as well as the virulence gene profiles among sequence types (STs). Sixty-two isolates were recovered from 16 herds in 3 Canadian Maritime Provinces: New Brunswick (14.5%), Nova Scotia (48.3%), and Prince Edward Island (37.1%). Of these, 9, 30, and 23 were recovered from post-calving, lactational samples, and post-mastitis samples, respectively. These 62 S. uberis isolates belonged to 34 STs; 11 isolates were typed to 9 known STs and 51 isolates were classified as one of 25 new STs. Thirteen isolates were part of major clonal complexes (CCs). Post-mastitis isolates contained 10 unique STs, lactational isolates contained 11 unique STs, and post-calving isolates had 3 STs. Each farm had only 1 isolate that was a unique ST except for STs 233, 851, 855, 857, 864, and 866, which were found in multiple cows per herd on more than one farm. ST851 and ST857 were found in each of the 3 sample types, with ST857 found in cows from all 3 Maritime provinces. These results indicate that S. uberis is a diverse non-clonal pathogen with specific STs residing in clonal clusters, carrying multiple AMR genes and virulence, with a diverse phenotypic AMR.

OBJECTIVE To determine usefulness of skin turgor and capillary refill time (CRT) for predicting changes in hydration status of working dogs after a 15-minute exercise period. ANIMALS 9 exercise-conditioned working dogs between 8 and 108 months of age. PROCEDURES Skin tent time (SkTT; time for tented skin on the forehead to return to an anatomically normal position) and CRT (time for occluded mucous membrane capillary vessels to return to the color visible before occlusion) were measured on dogs in a field setting and by video review. Body weight (BW), SkTT, CRT, and core body temperature were measured before and after a 15-minute exercise period. Exercise challenge was performed on days 1 and 8. RESULTS Time (day 1 vs day 8) did not significantly affect results; therefore, data were pooled for the 2 trial days. Mean ± SE BW decreased (but not significantly) by 0.83 ± 0.27% after exercise. The SkTT increased significantly (both field setting and video review) after exercise. Correlation between SkTT results for the field setting and video review (r = 0.68) was significant. The CRT decreased (but not significantly) after exercise. CONCLUSIONS AND CLINICAL RELEVANCE Dogs became mildly dehydrated (mean BW loss, 0.83%) during a 15-minute exercise period, and the mild dehydration was evident as a visually detectable change in skin turgor. Monitoring the SkTT appeared to be a useful strategy for predicting small shifts in hydration status of dogs during exercise. The CRT decreased and was not a significant predictor of a change in hydration status.

OBJECTIVE To evaluate effects of bite distance of an interlocking horizontal mattress epitendinous suture (IHMES) from the repair site on tensile strength of canine tendon repairs. SAMPLE 72 canine cadaveric superficial digital flexor tendons (SDFTs). PROCEDURES Transverse tenotomy was performed, and SDFTs were repaired with a locking-loop construct (LL construct) or 3 LL constructs with IHMES suture bites placed 5 (LL + 5ES construct), 10 (LL + 10ES construct), or 15 (LL + 15ES construct) mm from the transection site (18 SDFTs/group). Constructs were loaded to failure. Load at 1− and 3-mm gapping, yield force, failure load, and failure mode were evaluated. RESULTS Mean ± SD yield force and failure load for LL constructs were significantly lower than for IHMES constructs. Load at 1− and 3-mm gapping was significantly higher for IHMES constructs. Increasing the bite distance significantly increased construct strength (134.4 ± 26.1 N, 151.0 ± 16.8 N, and 182.1 ± 23.6 N for LL + 5ES, LL + 10ES, and LL + 15ES constructs, respectively), compared with strength for the LL construct. Failure mode differed significantly among constructs when an IHMES was used. CONCLUSIONS AND CLINICAL RELEVANCE Addition of an IHMES to an LL construct led to increased ultimate tensile strength by 2.5 times and significantly reduced gap formation. Increasing the IHMES bite distance increased yield force by 2.1, 2.3, and 2.7 times for bites placed 5, 10, and 15 mm from the tenotomy, respectively. Positioning an IHMES at a greater distance from the repair site provided superior biomechanical strength for tendon repairs in dogs.

OBJECTIVE To determine whether an enrofloxacin–silver sulfadiazine emulsion (ESS) labeled for treatment of otitis externa in dogs has ototoxic effects in rabbits following myringotomy. ANIMALS 6 healthy adult New Zealand White rabbits. PROCEDURES Rabbits were anesthetized for brainstem auditory-evoked response (BAER) tests on day 0. Myringotomy was performed, and BAER testing was repeated. Saline (0.9% NaCl) solution and ESS were then instilled in the left and right middle ears, respectively, and BAER testing was repeated prior to recovery of rabbits from anesthesia. Application of assigned treatments was continued every 12 hours for 7 days, and rabbits were anesthetized for BAER testing on day 8. Rabbits were euthanized, and samples were collected for histologic (6 ears/treatment) and scanning electron microscopic (1 ear/treatment) examination. RESULTS Most hearing thresholds (11/12 ears) were subjectively increased after myringotomy, with BAER measurements ranging from 30 to 85 dB in both ears. All day 8 hearing thresholds exceeded baseline (premyringotomy) values; results ranged from 30 to 85 dB and 80 to > 95 dB (the upper test limit) in saline solution–treated and ESS-treated ears, respectively. All ESS-treated ears had heterophilic otitis externa, epithelial hyperplasia of the external ear canal, various degrees of mucoperiosteal edema, and periosteal new bone formation on histologic examination. Scanning electron microscopy revealed that most outer hair cells in the ESS-treated ear lacked stereocilia or were absent. CONCLUSIONS AND CLINICAL RELEVANCE Results supported that ESS has ototoxic effects in the middle ear of rabbits. Further research is needed to confirm these findings. Myringotomized laboratory rabbits may be useful to study ototoxicity of drugs used in human medicine.