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- Author or Editor: Richard L. Walker x
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Abstract
Objective—To determine whether previously unidentified variations of the SzP protein of Streptococcus equi subsp zooepidemicus were present in horses with various clinical signs of infection and whether any relationship could be identified between SzP protein variants and naturally occurring clinical conditions.
Sample Population—23 isolates of S equi subsp zooepidemicus were recovered from specimens of horses with various clinical conditions and used as a representative population of isolates for evaluation of different SzP protein variants.
Procedure—Genetic heterogeneity of the isolates was demonstrated by repetitive extragenic palindromic- polymerase chain reaction analysis. The SzP gene was sequenced and the presumed protein sequence determined for each isolate. Characteristics of the SzP proteins were compared among the isolates and in relation to the clinical conditions of horses from which they were recovered.
Results—The signal peptide types, number of proline- glutamic acid-proline-lysine repeats, and anchor sequences were consistent with those previously described for the SzP protein. Many of the isolates clustered with 5 previously described types on the basis of the hypervariable region of the SzP protein. One additional variant, which represented 8 of the isolates, was identified. Particular motifs in the hypervariable region accounted for many of the differences among hypervariable types.
Conclusions and Clinical Relevance—The SzP protein appears to be limited to a selected number of types. Variations in the SzP protein are frequently determined on the basis of different motifs rather than random amino acid substitutions. There does not appear to be any association of SzP protein variations and clinical manifestations of infection in horses. (Am J Vet Res 2003;64:976–981)
Abstract
Objective—To compare the effectiveness of lincomycin and oxytetracycline for treatment of digital dermatitis (DD) in dairy cows through gross visual examination, histologic evaluation, and bacteriologic evaluation.
Design—Randomized controlled clinical trial.
Animals—25 cows with DD lesions from a commercial Holstein dairy herd.
Procedures—Cows with DD lesions were randomly assigned to 1 of 3 groups: topical treatment with 10 g of lincomycin hydrochloride (n = 11), topical treatment with 10 g of oxytetracycline hydrochloride (11), and no treatment (3) on days 1 and 2 (d1). Biopsy specimens were obtained for histologic examination from DD lesions prior to treatment and 28 or 31 days (d30) after treatment for histologic examination. Cows were clinically examined on d1, days 12 or 14 (d14), and d30.
Results—No difference was evident in clinical responses to lincomycin and oxytetracycline, so data were pooled; at d30, 8 of 11 of lincomycin-treated lesions and 7 of 11 oxytetracycline-treated lesions appeared visually healed, respectively. Gross visual examination suggested 73% (16/22) of treated cows were healed at d14 and 68% (15/22) of treated cows were healed on d30. Of the 15 lesions that appeared healed on d30, 7 of 15 were classified histologically as active (ulceration and bacterial invasion; 2/15) or incipient (5/15).
Conclusions and Clinical Relevance—Clinical responses to lincomycin and oxytetracycline did not differ. Agreement was good between gross visual and histologic assessments of DD lesions before treatment; agreement 1 month after treatment was variable. Histologic evaluation could not distinguish incomplete healing from lesion recurrence.
Abstract
Objective
To determine whether a humoral response against spirochetes isolated from papillomatous digital dermatitis (PDD) lesions is elicited in dairy cattle affected with PDD.
Sample Population
41 cattle with PDD from 8 dairies (study population) and 30 cattle from 2 dairies free of PDD (control population). Additionally evaluated were 32 cattle from a dairy with a past history of PDD but no current disease, and 52 cattle from a dairy with high prevalence of PDD, 25 with and 27 without detectable lesions.
Procedure
ELISA were used to evaluate the humoral response of all cattle to representative isolates from 2 groups of spirochetes of unknown species isolated from PDD lesions. Specificity of the response was evaluated, using immune sera prepared against each of the spirochetes, and by adsorption studies of immune and field sera. The potential for confounding by an antibody response to other spirochetes associated with diseases of cattle was assessed.
Results
The antibody response (specific) to both PDD spirochete groups of cows with PDD was significantly increased, compared with that of cows from PDD-free dairies. There was no association between antibody response to PDD-associated spirochetes and antibody response to other spirochetal diseases of cattle. None of the cattle from the dairy with previous history of PDD but without current disease were classified as test positive by either PDD ELISA. There was a significant (P < 0.01) difference in classification results for both PDD ELISA for cattle with PDD from the dairy with a high herd prevalence of PDD, compared with cattle without detectable disease from the same dairy.
Conclusions and Clinical Relevance
The humoral response in cattle with PDD lesions was significantly different from that in cattle without detectable lesions, thus providing additional information regarding the potential role of spirochetes isolated from PDD lesions in the etiopathogenesis of PDD. (Am J Vet Res 1997;58:744–748)
Summary
Disseminated Actinomycetales infections were diagnosed in 6 slender-horned gazelles at a zoologic park over a 17-month period. Nocardia and Mycobacterium spp were isolated. Possible predisposing causes leading to infection were investigated. Environmental contamination where the gazelles were housed was not high, and other breeds of gazelles at the park did not become infected, indicating that environmental exposure was not the sole factor involved. Information gathered from questionnaires sent to other zoologic parks and personnel communications indicated that this was not an isolated incident. Investigation into the genetic lineage of the gazelles revealed substantial inbreeding in prior generations. These findings suggested inbreeding may have been an important predisposing factor leading to infection. Careful scrutiny to ensure maximal heterozygosity of future breedings is warranted.
Abstract
Objective—To determine risk factors for Clostridium piliforme infection in neonatal foals on a Thoroughbred breeding farm in California.
Design—Case-control and retrospective cohort studies.
Animals—322 neonatal Thoroughbred foals either born on the study farm or born elsewhere but traveled to the farm with their dam during the 1998, 1999, and 2000 breeding seasons.
Procedure—Mare and foal records from 1998, 1999, and 2000 were examined, using case-control design methods to determine variables associated with increased risk of C piliforme infection in foals. Important risk factors identified in the case-control study were then reevaluated by use of a retrospective cohort design, using data from all neonatal foals present on the farm during the 3-year study period.
Results—Foals born between March 13 and April 13 were 7.2 times as likely to develop C piliforme infection as were those born at any other time of the foaling season. Foals of nonresident (visiting) mares were 3.4 times as likely to develop disease as were foals born to mares that were permanent residents of the study farm. Foals of mares < 6 years of age were 2.9 times as likely to develop disease as were foals born to older mares.
Conclusions and Clinical Relevance—Results of this research can be used to better understand the epidemiologic factors of C piliforme infection in horses. High-risk foals can be closely monitored to aid in early diagnosis and treatment, resulting in the best possible clinical outcome for affected individuals. (J Am Vet Med Assoc 2002;220:785–790)
Summary
During a 3-year period, 4 cases of bovine abortion attributable to Listeria ivanovii were diagnosed from 243 bovine fetuses submitted for diagnostic evaluation. Listeria monocytogenes was isolated only once from a bovine fetus during this same time period. Pathologic findings were similar to those seen in abortions attributable to L monocytogenes. Consistent management factors were not recognized and breed susceptibility was not apparent. Listeria ivanovii is most often associated with abortions from sheep and is rarely reported from cattle. On the basis of findings in this study, L ivanovii must be included as a potential cause of bovine abortions.
Objective
To determine whether ampicillin- and tetracycline-resistant strains of Pasteurella multocida and P haemolytica isolated from California cattle with pneumonia were spatially and temporally clustered and to compare overall estimates of percentages of these isolates resistant to these antimicrobials with estimates obtained on the basis of regional and temporal information.
Design
Epidemiologic study.
Sample Population
Records of P multocida and P haemolytica isolates obtained from lung or tracheal wash samples collected from California cattle with pneumonia between July 1, 1991 and July 31, 1996. Only isolates obtained from samples submitted by dairies and calf ranches were used.
Procedure
Spatial clustering of ampicillin- and tetracycline-resistant isolates was assessed by use of nearest-neighbor and Cuzick and Edwards' analyses. Linear clustering along a north-south line was assessed by use of runs and maximum length of runs tests. Temporal clustering was assessed by use of scan tests. Spatial-temporal clustering was assessed by use of Barton's method. Regional estimates of percentages of P multocida and P haemolytica resistant to ampicillin or tetracycline were calculated.
Results
There was significant spatial clustering of resistant isolates and significant linear clustering along a north-south line. Significant differences in regional estimates of percentages of antimicrobial-resistant isolates were found.
Clinical Implications
Results support the hypothesis that antimicrobial-resistant organisms can be clustered at the local level and reinforce the need to establish regional estimates of percentages of bacterial isolates that will be susceptible to commonly used antimicrobials. (J Am Vet Med Assoc 1998;212:1001–1005)
Objective
To identify risk factors associated with Salmonella menhaden associated disease in adult dairy cows during an outbreak in California.
Design
Case-control study.
Sample Population
8 case dairies that had ≥ 1 adult animal that had clinical signs of salmonellosis and from which S menhaden was isolated and 22 control dairies, 16 of which were matched on the basis of herd size and county and 6 of which were matched on the basis of herd size, county, and breed (Jersey).
Procedure
A questionnaire was developed and reviewed with the herdsman or owner of each dairy. Primary areas of concern were herd management, disease characteristics, and feed-related information.
Results
Use of 1 particular feed mill and feeding animal fat were significant risk factors for clinical disease attributable to S menhaden infection.
Clinical Implications
Feed should not be overlooked as a potential source of Salmonella organisms in dairy herds. (J Am Vet Med Assoc 1997;210:528–530)
Objective
To estimate prevalence of papillomatous digital dermatitis (PDD) in California dairies during 1993, to describe temporal and spatial patterns of PDD and response of cows to treatment, and to evaluate herd-related risk factors for PDD.
Design
Epidemiologic survey.
Sample Population
All southern California dairies and a 50% random sample of the rest of California dairies.
Procedure
A questionnaire was mailed to managers of 1,429 selected dairies.
Results
Prevalence of PDD during 1993 was significantly higher for dairies in the south (75.3%) and central (68.8%) regions, compared with north coast (33.3%) and north (23.1%) regions of the state. Herd mean and median proportions of affected cows in PDD-affected herds were 11.6 (SEM = 0.9) and 5%, respectively. Most (74%) dairy managers surveyed observed PDD for the first time during 1992 or 1993. Highest PDD activity was reported as taking place in summer in the south and in fall and winter in the north coast and north regions; an obvious pattern was not determined for the central region.
Clinical Implications
PDD was widespread in California dairies during 1993 and affected a high proportion of cows, especially in the south and central regions of the state. (J Am Vet Med Assoc 1996;209:1464–1467)
