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Objective—To determine aqueous humor flow rate (AHFR) in an avian species by use of anterior segment fluorophotometry.
Animals—9 healthy red-tailed hawks (Buteo jamaicensis; 4 males and 5 females) that ranged from 8 months to 8 years of age.
Procedures—A protocol was developed for fluorophotometric determination of AHFR. Topical administration of 10% fluorescein was used to load the corneas, and corneal and aqueous humor fluorescein concentrations were measured approximately 5, 6.5, and 8 hours later. Concentration-versus-time plots were generated, and slopes and cornea-to-aqueous humor concentration ratios from these plots were used to manually calculate flow rates.
Results—Mean ± SD AHFRs for the right eye, left eye, and both eyes were 3.17 ± 1.36 μL/min (range, 1.67 to 6.21 μL/min), 2.86 ± 0.88 μL/min (range, 2.04 to 4.30 μL/min), and 2.90 ± 0.90 μL/min (range, 1.67 to 4.42 μL/min), respectively. The AHFRs were similar for right and left eyes. These flow rates represented a mean aqueous humor transfer coefficient of 0.0082/min, which is similar to that of mammalian species.
Conclusions and Clinical Relevance—The AHFR in red-tailed hawks was similar to that of most mammalian species, and the fractional egress was almost identical to that of other species. This information will allow a greater understanding of aqueous humor flow in avian eyes, which is crucial when evaluating diseases that affect avian eyes as well as medications that alter aqueous humor flow.
Objective—To estimate the association between climate and airborne pollen and fungal factors and chronic obstructive pulmonary disease (COPD) in horses.
Sample Population—Data from 1,444 horses with a diagnosis of COPD.
Procedure—The Veterinary Medical Database was used to identify records of horses admitted to veterinary teaching hospitals in the United States and Canada between 1990 and 1999. Rainfall, mean minimum and maximum temperature, and maximum monthly pollen and fungal spore (mold) counts recorded at the city closest to where the hospital is located were identified for each month data were reported to the Veterinary Medical Database. Associations between climatic and aeroallergen data and monthly prevalence of COPD were estimated by use of crosscorrelation and logistic regression models.
Results—Significant positive correlations were found between prevalence of COPD and rainfall 3 months previously, minimum temperature 1 and 2 months previously, total pollen counts measured 3 months previously, and total mold counts measured during the same month and 1 month previously.
Conclusions and Clinical Relevance—Outdoor aeroallergens and climatic factors may contribute to the occurrence of COPD in horses. (Am J Vet Res 2005;66:818–824)
Objective—To determine the association between soil type and paratuberculosis in cattle.
Sample Population—Soil samples and test results for paratuberculosis in 92 Indiana cattle herds.
Procedure—Testing records from herds in which ≥ 20 cattle were tested for paratuberculosis by use of an ELISA between 1998 and 2002 were identified. Soil type was characterized on the basis of herd location. Clusters of herds with seroprevalence greater than the median seroprevalence were identified. Association between clusters and soil types was estimated by logistic regression, adjusted for herd type (dairy or beef).
Results—A spatial cluster of greater than the median seroprevalence was identified in northeast Indiana. Soils with low silt content were associated (odds ratio [OR], 7.2; 95% confidence interval [CI], 2.1 to 24.5) with this cluster. Adjusting for herd type did not substantially alter this association (OR, 6.7). Herds located in areas with sandy loam (OR, 6.2; 95% CI, 1.4 to 27.4) and loam (OR, 3.6; 95% CI, 1.0 to 13.2) soils were also more likely to be within the cluster of greater than the median seroprevalence. Herds located in areas of silt loam soils were less likely (OR, 0.2; 95% CI, 0.1 to 0.7) to be included in this cluster.
Conclusions and Clinical Relevance—Spatial distribution of herds with greater than the median seroprevalence of paratuberculosis was associated with soil characteristics. Survival of Mycobacterium avium subsp paratuberculosis may be enhanced by silt or sand content in loamy soils. These results may be used to modify paratuberculosis control programs. ( Am J Vet Res 2004;65:10–14)
Objective—To determine if clopidogrel enhanced the thrombolytic rate of tissue-plasminogen activator (t-PA) on an in vitro feline whole blood thrombosis model.
Animals—9 purpose-bred cats.
Procedure—Blood obtained from cats before (baseline) and after treatment with clopidogrel (75 mg, PO, q 24 h for 3 days) was anticoagulated with sodium citrate (9:1 volume-to-volume ratio) to which 1 µCi of I125- fibrinogen was added. Thrombi were formed by the addition of calcium chloride and bovine thrombin. Thrombi were placed into autologous plasma to which 0.1 mg of t-PA was added. Plasma samples were collected at different time points to determine the amount of released I125-fibrin split products. Thrombolytic rates were calculated by determining the time to 25%, 50%, and 75% thrombolysis (t25, t50, and t75, respectively). Confidence intervals for t25, t50, and t75 at baseline were compared with those after treatment.
Results—There were no significant differences in thrombolytic rates between values obtained at baseline and after clopidogrel treatment (t25, 18.0 vs 18.5 minutes; t50, 63.3 vs 65.6 minutes; and t75, 163.0 vs 170.1 minutes, respectively).
Conclusions and Clinical Relevance—Clopidogrel did not have an effect on the rate of thrombolysis of feline whole blood thrombi induced by t-PA in this in vitro model. (Am J Vet Res 2004;65:715–719)
Objective—To identify risk factors for recurrent airway obstruction (RAO) among horses examined at veterinary teaching hospitals in North America.
Design—Retrospective case-control study.
Animals—1,444 horses with RAO and 1,444 control horses examined for other reasons.
Procedure—The Veterinary Medical Database was searched for records of horses in which RAO was diagnosed. A control group was identified by randomly selecting a horse with a diagnosis other than RAO that matched the institution and year of admission for each of the horses with RAO. Information obtained included hospital, admission year and month, age, sex, breed, and discharge status. The association between risk factors and diagnosis of RAO was estimated with logistic regression models.
Results—The risk of RAO increased significantly with age, with horses ≥ 7 years old being 6 to 7 times as likely to have RAO as were horses ≤ 4 years old. Thoroughbreds were 3 times as likely to have RAO as were ponies. Horses were 1.6 and 1.5 times as likely to be examined because of RAO during winter and spring, respectively, than they were during summer.
Conclusions and Clinical Relevance—Results suggest that RAO was more likely to be diagnosed in females, horses ≥ 4 years old, and Thoroughbreds and that RAO has a seasonal distribution. (J Am Vet Med Assoc 2003;223:1645–1650)
Objective—To determine whether West Nile virus (WNV) disease hyperendemic foci (hot spots) exist within the horse population in Texas and, if detected, to identify the locations.
Sample Population—Reports of 1,907 horses with WNV disease in Texas from 2002 to 2004.
Procedures—Case data with spatial information from WNV epidemics occurring in 2002 (1,377 horses), 2003 (396 horses), and 2004 (134 horses) were analyzed by use of the spatial scan statistic (Poisson model) and kriging of empirical Bayes smoothed county attack rates to determine locations of horses with WNV disease in which affected horses were consistently (in each of the 3 study years) clustered (hyperendemic foci, or hot spots).
Results—2 WNV hot spots in Texas, an area in northwestern Texas and an area in eastern Texas, were identified with the scan statistic. Risk maps of the WNV epidemics were qualitatively consistent with the hot spots identified.
Conclusions and Clinical Relevance—WNV hot spots existed within the horse population in Texas (2002 to 2004). Knowledge of disease hot spots allows disease control and prevention programs to be made more efficient through targeted surveillance and education.
Objective—To compare gentamicin concentrations achieved in synovial fluid and joint tissues during IV administration and continuous intra-articular (IA) infusion of the tarsocrural joint in horses.
Animals—18 horses with clinically normal tarsocrural joints.
Procedure—Horses were assigned to 3 groups (6 horses/group) and administered gentamicin (6.6 mg/kg, IV, q 24 h for 4 days; group 1), a continuous IA infusion of gentamicin into the tarsocrural joint (50 mg/h for 73 hours; group 2), or both treatments (group 3). Serum, synovial fluid, and joint tissue samples were collected for measurement of gentamicin at various time points during and 73 hours after initiation of treatment. Gentamicin concentrations were compared by use of a Kruskal-Wallis ANOVA.
Results—At 73 hours, mean ± SE gentamicin concentrations in synovial fluid, synovial membrane, joint capsule, subchondral bone, and collateral ligament of group 1 horses were 11.5 ± 1.5 μg/mL, 21.1 ± 3.0 μg/g, 17.1 ± 1.4 μg/g, 9.8 ± 2.0 μg/g, and 5.9 ± 0.7 μg/g, respectively. Corresponding concentrations in group 2 horses were 458.7 ± 130.3 μg/mL, 496.8 ± 126.5 μg/g, 128.5 ± 74.2 μg/g, 99.4 ± 47.3 μg/g, and 13.5 ± 7.6 μg/g, respectively. Gentamicin concentrations in synovial fluid, synovial membrane, and joint capsule of group 1 horses were significantly lower than concentrations in those samples for horses in groups 2 and 3.
Conclusions and Clinical Relevance—Continuous IA infusion of gentamicin achieves higher drug concentrations in joint tissues of normal tarsocrural joints of horses, compared with concentrations after IV administration.
Objective—To estimate serovar-specific prevalence of leptospirosis by use of veterinary teaching hospital and laboratory submission data; describe annual and seasonal patterns of leptospirosis; and identify risk factors for age, sex, and breed.
Animals—90 dogs with leptospirosis.
Procedures—Hospital records of dogs examined at Purdue University Veterinary Teaching Hospital with a diagnosis of leptospirosis and laboratory records of dogs from which sera were tested for antibodies against Leptospira spp at Purdue University Animal Disease Diagnostic Laboratory from 1997 through 2002 were reviewed. The likely infecting Leptospira serovar was identified. Seasonal and annual prevalences were calculated by use of hospital population at risk (hospital cases) or serologic testing submissions (diagnostic laboratory cases). Age-, sex-, and breed-specific risk factors for hospital cases were estimated by odds ratios.
Results—Of the 39 hospitalized dogs identified, 34 had been serologically tested, and 22 of those were infected with Leptospira kirschneri serovar grippotyphosa. Of the 51 diagnostic laboratory cases, 59% had a reciprocal titer ≥ 800 against serovar grippotyphosa. Diagnostic laboratory cases were more common in summer, whereas hospital cases of leptospirosis were more common in fall. Male dogs were at significantly greater risk of leptospirosis than female dogs; and dogs 4 to 6.9 years old were at significantly greater risk than dogs < 1 year old.
Conclusions and Clinical Relevance—L kirschneri serovar grippotyphosa infection was associated with most cases of leptospirosis in dogs. Use of an effective vaccine that includes this serovar is advisable for dogs at risk of leptospirosis. (J Am Vet Med Assoc 2004;224:1958–1963)
Objective—To determine whether there was a temporal trend in prevalence of leptospirosis among dogs in the United States and Canada and to determine whether age, sex, and breed were risk factors for the disease.
Animals—1,819,792 dogs examined at 22 veterinary teaching hospitals between 1970 and 1998.
Procedures—The Veterinary Medical Data Base was searched for records of dogs in which a diagnosis of leptospirosis was made, and hospital prevalence was calculated. Logistic regression was used to examine the association between leptospirosis and age, sex, and breed.
Results—677 dogs with leptospirosis were identified. Thus, hospital prevalence was 37 cases/100,000 dogs examined. A significant increase in leptospirosis prevalence between 1983 and 1998 was identified. Male dogs were at significantly greater risk of leptospirosis than were female dogs; dogs between 4 and 6.9 years old and between 7 and 10 years old were at significantly greater risk than dogs < 1 year old; and herding dogs, hounds, working dogs, and mixed-breed dogs were at significantly greater risk than companion dogs.
Conclusions and Clinical Relevance—The prevalence of leptospirosis among dogs examined at veterinary teaching hospitals in the United States and Canada has increased significantly since 1983. Male dogs of working and herding breeds were at greater risk. (J Am Vet Med Assoc 2002;220:53–58)
Objective—To identify environmental risk factors for leptospirosis.
Animals—36 dogs with leptospirosis and 138 dogs seronegative for leptospirosis as determined by microscopic agglutination test for antibodies against Leptospira spp.
Procedure—Medical records of dogs evaluated for leptospirosis from 1997 though 2002 were identified. Owner address was used to geocode locations of dogs, and location-specific environmental risk factor data were obtained by use of a geographic information system. Risk of leptospirosis was estimated by odds ratios, controlling for potential confounding by dog age, sex, and breed.
Results—Leptospirosis in 19 of the 30 dogs in which an infecting Leptospira serovar could be identified was associated with Leptospira kirschneri serovar grippotyphosa infection. Dogs in which a diagnosis of leptospirosis was made, and dogs with leptospirosis caused by L kirschneri serovar grippotyphosa, were more likely to have addresses located in areas classified as rural in 1990 but urban in 2000. By use of information on recent urbanization and a logistic regression model, the status of 81.6% and 89.8% of dogs with leptospirosis and leptospirosis caused by serovar grippotyphosa, respectively, were correctly classified. Other environmental variables (proximity to streams, recreational areas, farmland, wetlands, areas subject to flooding, and areas with poor drainage; annual rainfall; and county cattle or pig population) did not significantly improve accuracy of classification.
Conclusions and Clinical Relevance—Dogs in periurban areas are at greater risk of leptospirosis. Vaccination of dogs in these areas to protect against leptospirosis should be considered. (J Am Vet Med Assoc 2004;225:72–77)