A study of Ontario swine farms positive for Porcine reproductive and respiratory syndrome virus (PRRSV) tested the association between genetic similarity of the virus and similarity of clinical signs reported by the herd owner. Herds were included if a positive result of polymerase chain reaction for PRRSV at the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, was found between September 2004 and August 2007. Nucleotide-sequence similarity and clinical similarity, as determined from a telephone survey, were calculated for all pairs of herds. The Mantel test indicated that clinical similarity and sequence similarity were weakly correlated for most clinical signs. The generalized additive model indicated that virus homology with 2 vaccine viruses affected the association between sequence similarity and clinical similarity. When the data for herds with vaccine-like virus were removed from the dataset there was a significant association between virus similarity and similarity of the reported presence of abortion, stillbirth, preweaning mortality, and sow/boar mortality. Ownership similarity was also found to be associated with virus similarity and with similarity of the reported presence of sows being off-feed, nursery respiratory disease, nursery mortality, finisher respiratory disease, and finisher mortality. These results indicate that clinical signs of PRRS are associated with PRRSV genotype and that herd ownership is associated with both of these.

Objective—To compare repeatability and equivalency of measures of femoral trochlea depth and trochlear angle in red foxes (Vulpes vulpes) determined by use of radiography, ultrasonography, and digital photography of cadaver limbs. Sample—24 pelvic limbs from 12 red fox cadavers. Procedures—Cranioproximal-craniodistal oblique (skyline) and lateromedial radiographic views of the stifle joint and ultrasonographic images at 5 locations along the femoral trochlea were used in the study. Spacing of the 5 locations was determined on the basis of patellar position with the stifle joint at various caudal angles ranging from 96° to maximal extension (approx 170°). Ultrasonographic measurements were compared with those obtained at matched locations on photographs of anatomic preparations. Trochlear depth was assessed with all 3 image formats, and trochlear angle (measured between the trochlear ridges and sulcus) was assessed on radiographs and ultrasonographic images. Patellar thickness was measured on radiographs. Values obtained were compared by means of ANOVA, modified Bland-Altman plots, and repeatability testing. Results—Depth measurement repeatability was considered good for all modalities. Small but significant differences between mean ultrasonographic trochlear depth and anatomic (photographic) measurements were found at 3 locations; 95% limits of agreement for paired anatomic and ultrasonographic measurements were wide. The ratio of trochlear depth to radiographic patellar thickness was approximately 30% for all modalities. Trochlear angle measurements were more variable than trochlear depth measurements, especially in the distal aspect of the trochlea. Conclusions and Clinical Relevance—Paired anatomic and ultrasonographic measurements did not appear equivalent in this study, possibly attributable to imprecise probe location, which could limit quantitative use of ultrasonography in assessing proximal trochlear depth in a clinical setting.

Objective—To compare effectiveness and complications associated with peribulbar and retrobulbar anesthesia with bupivacaine in cats. Animals—6 healthy adult cats. Procedures—Cats were sedated with dexmedetomidine and received a peribulbar injection of 0.5% bupivacaine (1.5 mL), iopamidol (0.5 mL), and saline (0.9% NaCl) solution (1 mL) or retrobulbar injection of 0.5% bupivacaine (0.75 mL) and iopamidol (0.25 mL) in a crossover study with ≥ 2 weeks between treatments. The contralateral eye was the control. Injectate distribution was evaluated with CT. After atipamezole administration, periocular and corneal sensations, intraocular pressure (IOP), and ocular reflexes and appearance were evaluated for 24 hours. Results—All peribulbar and 3 of 6 retrobulbar injections resulted in CT evidence of intraconal injectate. Corneal sensation and periocular skin sensation were absent or significantly reduced relative to that for control eyes for 3 hours after peribulbar injection. Mean ± SD IOP immediately after injection was significantly higher for eyes with peribulbar injections (33 ± 12 mm Hg) than for control eyes or eyes with retrobulbar injections (both 14 ± 4 mm Hg) but 10 minutes later decreased to 18 ± 3 mm Hg. Exophthalmos, chemosis, and ptosis were evident in most injected eyes, and irritation was evident in 3 of 6 peribulbar-injected and 1 of 6 retrobulbar-injected eyes. All conditions resolved within 14 hours. Conclusions and Clinical Relevance—Peribulbar injection resulted in intraconal deposition of bupivicaine in a higher percentage of cats than did retrobulbar injection and induced notable anesthesia relative to that for the control eye; however, IOP increased temporarily.

Objective—To determine the effects of UVB radiation produced by artificial lights on serum 25-hydroxyvitamin D concentrations in domestic rabbits (Oryctolagus cuniculi) Animals—9 juvenile domestic rabbits. Procedures—After an acclimation period, rabbits were anesthetized with isoflurane, and an initial blood sample was collected for determination of serum 25-hydroxyvitamin D concentration. Rabbits were randomly assigned to receive 12-hour exposure to UVB radiation produced by 2 compact fluorescent lights daily (n = 5) or no UVB supplementation (4) commencing on day 1. The UVB radiation emitted into the cage was measured at 9 points approximately 34 cm from the surface of the UVB light sources (representing the position of the rabbits in the cage) after 10 hours of exposure on days 1, 8, and 14. On day 14, another blood sample was collected from anesthetized rabbits for determination of serum 25-hydroxyvitamin D concentration. Results—The UVB radiation level was 8.3 to 58.1 μW/cm2 for the exposed rabbits and consistently < 0.001 μW/cm2 for the control rabbits. Mean ± SD serum 25-hydroxyvitamin D concentrations in the rabbits that were or were not provided supplemental UVB radiation for 14 days differed significantly (66.4 ± 14.3 nmol/L and 31.7 ± 9.9 nmol/L, respectively). Conclusions and Clinical Relevance—Exposure to UVB radiation produced by artificial light significantly increased serum 25-hydroxyvitamin D concentration in juvenile rabbits. Because vitamin D is an essential hormone in vertebrates, these findings suggested that the provision of supplemental UVB radiation to captive rabbits may be important.

Objective—To evaluate the effects of cisapride and metoclopramide hydrochloride administered orally on the lower esophageal sphincter (LES) resting pressure in awake healthy dogs. Animals—6 adult Beagles. Procedures—Each dog was evaluated after administration of a single dose of cisapride (0.5 mg/kg), metoclopramide (0.5 mg/kg), or placebo (empty gelatin-free capsule) in 3 experiments performed at 3-week intervals. To measure LES pressure, a high-resolution manometry catheter equipped with 40 pressure sensors spaced 10 mm apart was used. For each experiment, LES pressure was recorded during a 20-minute period with a virtual electronic sleeve emulation before treatment (baseline) and at 1, 4, and 7 hours after drug or placebo administration. A linear mixed-effects model was used to test whether the 3 treatments affected LES pressure differently. Results—In the cisapride, metoclopramide, and placebo experiments, median baseline LES pressures were 29.1, 30.5, and 29.0 mm Hg, respectively. For the cisapride, metoclopramide, and placebo treatments, median LES pressures at 1 hour after administration were 44.4, 37.8, and 36.6 mm Hg, respectively; median LES pressures at 4 hours after administration were 50.7, 30.6, and 31.1 mm Hg, respectively; and median LES pressures at 7 hours after administration were 44.3, 28.5, and 33.3 mm Hg, respectively. The LES pressures differed significantly only between the placebo and cisapride treatments. Conclusions and Clinical Relevance—Results suggested that orally administered cisapride may be of benefit in canine patients for which an increase in LES pressure is desirable, whereas orally administered metoclopramide did not affect LES resting pressures in dogs.

Objective—To ultrasonographically measure the thickness of the individual wall layers of the duodenum, jejunum, and colon of dogs. Animals—85 dogs with no clinical signs or ultrasonographic evidence of gastrointestinal tract disease. Procedures—Total wall thickness and thickness of the mucosa, submucosa, muscularis, and serosa were measured ultrasonographically in the duodenum, jejunum, and colon of each dog. Results—The mucosal layer was the thickest layer of the duodenum and jejunum. There was a significant difference in thickness of the mucosal layer between small and large dogs. Mean ± SD thickness of the mucosal layer of the duodenum for small, medium, and large dogs was 2.4 ± 0.5 mm, 2.6 ± 0.6 mm, and 2.8 ± 0.5 mm, respectively. Mean ± SD thickness of the mucosal layer of the jejunum for small, medium, and large dogs was 1.8 ± 0.4 mm, 2.0 ± 0.4 mm, and 2.2 ± 0.5 mm, respectively. The remaining wall layers of the duodenum and jejunum were similar in thickness, and there were no significant differences among small, medium, and large dogs. All layers contributed equally to the total colonic wall thickness. Mean ± SD thickness of the colonic wall for small, medium, and large dogs was 1.5 ± 0.3 mm, 1.4 ± 0.5 mm, and 1.6 ± 0.4 mm, respectively. Conclusions and Clinical Relevance—Values for thickness of the wall layers of the duodenum, jejunum, and colon of dogs reported here may be useful for assessing gastrointestinal tract diseases primarily targeting a specific wall layer.

This study aimed to investigate and compare the antagonistic effects of atipamezole, yohimbine, and prazosin on xylazine-induced diuresis in clinically normal cats. Five cats were repeatedly used in each of the 9 groups. One group was not medicated. Cats in the other groups received 2 mg/kg BW xylazine intramuscularly, and saline (as the control); 160 μg/kg BW prazosin; or 40, 160, or 480 μg/kg BW atipamezole or yohimbine intravenously 0.5 h later. Urine and blood samples were collected 10 times over 8 h. Urine volume, pH, and specific gravity; plasma arginine vasopressin (AVP) concentration; and creatinine, osmolality, and electrolyte values in both urine and plasma were measured. Both atipamezole and yohimbine antagonized xylazine-induced diuresis, but prazosin did not. The antidiuretic effect of atipamezole was more potent than that of yohimbine but not dose-dependent, in contrast to the effect of yohimbine at the tested doses. Both atipamezole and yohimbine reversed xylazine-induced decreases in both urine specific gravity and osmolality, and the increase in free water clearance. Glomerular filtration rate, osmolar clearance, and plasma electrolyte concentrations were not significantly altered. Antidiuresis of either atipamezole or yohimbine was not related to the area under the curve for AVP concentration, although the highest dose of both atipamezole and yohimbine increased plasma AVP concentration initially and temporarily, suggesting that this may in part influence antidiuretic effects of both agents. The diuretic effect of xylazine in cats may be mediated by α2-adrenoceptors but not α1-adrenoceptors. Atipamezole and yohimbine can be used as antagonistic agents against xylazine-induced diuresis in clinically normal cats.

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are retroviruses found within domestic and wild cat populations. These viruses cause severe illnesses that eventually lead to death. Housing cats communally for long periods of time makes shelters at high risk for virus transmission among cats. We tested 548 cats from 5 different sites across the island of Newfoundland for FIV and FeLV. The overall seroprevalence was 2.2% and 6.2% for FIV and FeLV, respectively. Two sites had significantly higher seroprevalence of FeLV infection than the other 3 sites. Analysis of sequences from the FeLV env gene (envelope gene) from 6 positive cats showed that 4 fell within the FeLV subtype-A, while 2 sequences were most closely related to FeLV subtype-B and endogenous feline leukemia virus (en FeLV). Varying seroprevalence and the variation in sequences at different sites demonstrate that some shelters are at greater risk of FeLV infections and recombination can occur at sites of high seroprevalence.

Osteoarthritis (OA) of the metacarpophalangeal joint is the most common articular disease in polo ponies leading to early retirement. A biomarker that would discriminate between pathological and physiological changes secondary to exercise could be helpful in OA prevention. The aim of this study was to investigate the effects of polo training on synovial fluid biomarkers of inflammation and cartilage turnover in polo ponies of different skill levels. Synovial fluid samples were collected from metacarpophalangeal joints of polo ponies before and during the polo season (320 d). Nucleated cells, soluble protein, prostaglandin E2 (PGE2), glycosaminoglycans (GAG), and urea were measured. The main synovial fluid GAG are chondroitin sulphate (CS, ~25 μg/mL) and hyaluronic acid (HA, ~400 μg/mL). After a polo match, a transitory increase in protein and PGE2, but not CS and HA, occurred (expressed as urea ratio), returning to basal levels in 24 h. During the polo season, the number of synovial fluid nucleated cells was always in the normal range. Increases in protein and HA occurred during the initial 40 to 80 d, returning to basal levels afterwards. In contrast, in polo prospects the concentration of CS steadily increased during the season. Long-term follow-up revealed that the synovial fluid CS was significantly higher in polo ponies that developed joint diseases within 24 months following our study. In conclusion, CS seems to be an early marker of articular cartilage damage.

Canine distemper is a highly contagious disease with high incidence and lethality in the canine population. The objective of this study was to evaluate the efficacy of antiviral action with ribavirin (RBV), interferon-alpha (IFNa), and combinations of RBV and IFN a against canine distemper virus (CDV). Vero cells inoculated with CDV were treated with RBV, IFNa, and combinations of these drugs. The efficacy to inhibit viral replication was evaluated by adding the compounds at different times to determine which step of the viral replicative process was affected. Both drugs were effective against CDV in vitro. The IFNa was the most active compound, with an average IC50 (50% inhibitory concentration) value lower than the IC50 of the RBV. Ribavirin (RBV) was more selective than IFN a, however, and neither drug showed extracellular antiviral activity. The combination of RBV and IFN a exhibited antiviral activity for the intra- and extracellular stages of the replicative cycle of CDV, although the intracellular viral inhibition was higher. Both RBV and IFN a showed high antiviral efficacy against CDV, and furthermore, RBV 1 IFNa combinations have shown greater interference range in viral infectivity. These compounds could potentially be used to treat clinical disease associated with CDV infection.