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)
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.
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)
Objective—To evaluate sensitivity of microbial culture
of pooled fecal samples for detection of
Mycobacterium avium subsp paratuberculosis (MAP)
in large dairy herds and assess the use of the method
for estimation of MAP prevalence.
Animals—1,740 lactating cows from 29 dairy herds
Procedure—Serum from each cow was tested by
use of a commercial ELISA kit. Individual fecal samples
were cultured and used to create pooled fecal
samples (10 randomly selected fecal samples/pool; 6
pooled samples/herd). Sensitivity of MAP detection
was compared between Herrold's egg yolk (HEY) agar
and a new liquid culture method. Bayesian methods
were used to estimate true prevalence of MAP-infected
cows and herd sensitivity.
Results—Estimated sensitivity for pooled fecal
samples among all herds was 0.69 (25 culture-positive
pools/36 pools that were MAP positive).
Sensitivity increased as the number of culture-positive
samples in a pool increased. The HEY agar
method detected more infected cows than the liquid
culture method but had lower sensitivity for
pooled fecal samples. Prevalence of MAP-infected
cows was estimated to be 4% (95% probability
interval, 2% to 6%) on the basis of culture of
pooled fecal samples. Herd-level sensitivity estimate
ranged from 90% to 100% and was dependent
on prevalence in the population and the sensitivity
for culture of pooled fecal samples.
Conclusions and Clinical Relevance—Use of pooled
fecal samples from 10 cows was a cost-effective tool
for herd screening and may provide a good estimate
of the percentage of MAP-infected cows in dairy
herds with a low prevalence of MAP. (Am J Vet Res