Objective—To estimate the prevalence of fecal shedding of Salmonella spp among bovine patients at a veterinary teaching hospital, to identify risk factors for fecal shedding of Salmonella organisms, and to characterize the serotypes.
Design—Retrospective cohort study.
Sample Population—5,398 hospitalized cattle.
Procedures—Data were collected for all cattle admitted during an 11-year period. Fecal shedding of Salmonella spp was determined by means of standard bacteriologic culture. Multivariable logistic regression models were used to identify risk factors for shedding of Salmonella spp among patients.
Results—The prevalence of Salmonella shedding among clinical suspects was 6.5% (50/768), whereas that among nonsuspects tested through routine surveillance was 2.5% (50/2,020). Among clinical suspect calves, fecal shedding of Salmonella spp was more likely for those admitted in the fall (odds ratio [OR], 5.9), those with septicemia (OR, 3.3), or those with an umbilical hernia (OR, 8.6). Among clinical suspect adult cattle, those with enteritis (OR, 9.9) or metritis (OR, 5.2) were more likely to be shedding Salmonella spp. Among nonsuspect cattle, none of the variables were significant predictors of shedding status. Twenty-one serotypes were detected during the study period, with the most common being Salmonella enterica serotypes Typhimurium (33%), Newport (23%), and Agona (12%).
Conclusions and Clinical Relevance—Seasonal and disease risk factors for fecal shedding of Salmonella spp were evident among clinical suspect cattle admitted to a veterinary teaching hospital. In contrast, lack of significant associations among nonsuspect cattle would suggest that targeted screening within this population is not warranted.
Objective—To determine whether, and at what time,
penicillin enters milk at a concentration that is
detectable following bulbar subconjunctival injection
in lactating dairy cows.
Design—Randomized clinical trial.
Animals—66 Holstein cows that were at least 2
weeks past calving and had not been treated with
antibiotics in the preceding 30 days.
Procedure—Cows were randomly assigned to
receive a treatment of 1 ml (300,000 units) procaine
penicillin G by bulbar subconjunctival injection or
remain untreated. Composite milk samples were collected
immediately before treatment and 4, 10, 16,
22, 28, and 40 hours after treatment. Milk samples
were tested by use of a commercial test for β-lactam
Results—Among penicillin-treated cows, the first
positive test results were observed 4 hours after
treatment, and the last positive result was observed
22 hours after treatment. The percentages of positive
test results before treatment and at 4, 10, 16, 22, 28,
and 40 hours after treatment were 0, 9, 87, 42, 8, 0,
and 0%, respectively. None of the untreated cows
had positive test results for β-lactam antibiotics at any
Conclusions and Clinical Relevance—Penicillin was
detected in milk for up to 22 hours after a single subconjunctival
injection of procaine penicillin G in cows.
This result should be considered when recommending
milk withholding periods following the administration
of penicillin by this route in lactating dairy cows.
(J Am Vet Med Assoc 2000;217:369–371)
Objective—To determine the phase and quantitate the electromyographic (EMG) activity of the genioglossus, geniohyoideus, hyoepiglotticus, omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles of clinically normal horses during strenuous exercise.
Animals—7 clinically normal adult horses (2 Thoroughbreds and 5 Standardbreds).
Procedures—Bipolar electrodes were surgically implanted in the aforementioned muscles, and horses were subjected to an incremental exercise test on a high-speed treadmill. The EMG, heart rate, respiratory rate, and static pharyngeal airway pressures were measured during exercise. The EMG was measured as mean electrical activity (MEA). The MEA values for maximal exercise intensity (13 or 14 m/s) were expressed as a percentage of the MEA measured at an exercise intensity of 6 m/s.
Results—MEA was detected during expiration in the genioglossus, geniohyoideus, sternohyoideus, and thyrohyoideus muscles and during inspiration in the hyoepiglotticus and sternothyroideus muscles. Intensity of the MEA increased significantly with exercise intensity in the genioglossus, geniohyoideus, and hyoepiglotticus muscles. Intensity of the MEA increased significantly in relation to expiratory pharyngeal pressure in the geniohyoideus and hyoepiglotticus muscles.
Conclusions and Clinical Relevance—Once exercise intensity reached 6 m/s, no quantifiable additional increase in muscular activity was detected in the omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles. However, muscles that may affect the diameter of the oropharynx (genioglossus and geniohyoideus muscles) or rima glottis (hyoepiglotticus muscle) had activity correlated with the intensity of exercise or expiratory pharyngeal pressures. Activity of the muscles affecting the geometry of the oropharynx may be important in the pathophysiologic processes associated with nasopharyngeal patency.
OBJECTIVE To describe the antimicrobial resistance patterns of Salmonella isolates obtained from horses in the northeastern United States and to identify trends in resistance to select antimicrobials over time.
SAMPLE 462 Salmonella isolates from horses.
PROCEDURES Retrospective data were collected for all Salmonella isolates obtained from equine specimens that were submitted to the Cornell University Animal Health Diagnostic Center between January 1, 2001, and December 31, 2013. Temporal trends in the prevalence of resistant Salmonella isolates were investigated for each of 13 antimicrobials by use of the Cochran-Armitage trend test.
RESULTS The prevalence of resistant isolates varied among antimicrobials and ranged from 0% (imipenem) to 51.5% (chloramphenicol). During the observation period, the prevalence of resistant isolates decreased significantly for amoxicillin—clavulanic acid, ampicillin, cefazolin, cefoxitin, ceftiofur, chloramphenicol, and tetracycline and remained negligible for amikacin and enrofloxacin. Of the 337 isolates for which the susceptibility to all 13 antimicrobials was determined, 138 (40.9%) were pansusceptible and 192 (57.0%) were multidrug resistant (resistant to ≥ 3 antimicrobial classes). The most common serovar isolated was Salmonella Newport, and although the annual prevalence of that serovar decreased significantly over time, that decrease had only a minimal effect on the observed antimicrobial resistance trends.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that current antimicrobial use in horses is not promoting the emergence and dissemination of antimicrobial-resistant Salmonella strains in the region served by the laboratory.
Objective—To determine prevalence of udder cleft
dermatitis in a dairy herd that was experiencing an
outbreak of sarcoptic mange.
Animals—1,597 Holstein cows and late-gestation
Procedure—Animals were examined for udder cleft
dermatitis and for skin lesions consistent with sarcoptic
or chorioptic mange. Skin scrapings were collected
from 56 cows and examined for ectoparasites.
The herd was revisited 1 year later, and prevalences
of udder cleft dermatitis and lesions consistent with
mange were determined in 506 cows.
Results—Of the 1,597 cattle examined, 280 (18%)
had udder cleft dermatitis, and 1,397 (87.5%) had
lesions consistent with mange. In 43 of 56 (77%)
cows, skin scrapings revealed Sarcoptes mites. Udder
cleft dermatitis was significantly more common in
older than in younger cows. In first-lactation cows,
udder cleft dermatitis was less common during the
first 4 months of lactation than in the later stages of
lactation, but udder cleft dermatitis was identified in
cows in all stages of lactation and in cows that were
not lactating. The herd was treated with eprinomectin
to control mites, and prevalence of lesions consistent
with mange 1 year later was only 2.8%. However,
prevalence of udder cleft dermatitis was still 12%.
Conclusions and Clinical Relevance—Results suggest
that cows in any stage of lactation and cows that
are not lactating can have udder cleft dermatitis but
that lesions are more common in older cows. Control
of sarcoptic mange was accompanied by a moderate
reduction in the prevalence of udder cleft dermatitis
but did not eliminate the condition. (J Am Vet Med
Objective—To evaluate the health and performance
of young dairy calves vaccinated with a commercial
Mannheimia haemolytica and Pasteurella multocida
Design—Randomized clinical trial.
Animals—358 Holstein dairy calves between 14 and
20 days of age on 8 farms.
Procedure—Calves were randomly assigned to a
control or vaccinated group. The vaccine used was a
commercial modified-live M haemolytica and P multocida
vaccine that was administered on days 0 and
14. Calf weight was measured on day 0 and monthly
for 3 months. Farmers were asked to record any treatment
given to the calves and the reason for treatment
during the 4 months of the study. Blood was collected
from all calves on days 0 and 28, and titers of antibodies
to M haemolyticawere determined by means
of direct bacterial agglutination.
Results—Mean daily gain was not significantly different
between vaccinated and control calves. Vaccinated
calves had a significantly greater increase in antibody
titers (5.3-fold increase), compared with control calves
(3.6-fold increase). There was no significant difference
between vaccinated and control calves for any of the
treatment outcomes (number and duration of treatments
and age at first and last treatments).
Conclusions and Clinical Relevance—Results suggest
that the M haemolytica and P multocidavaccine,
given twice 2 weeks apart, was effective in increasing
titers of antibodies against M haemolytica in young
dairy calves but did not improve calf performance or health. (J Am Vet Med Assoc 2001;219:1739–1742)
Objective—To evaluate effect of twin birth calvings on milk production, reproductive performance, and survival of lactating cows.
Design—Retrospective observational cohort study.
Animals—33,868 cows from 20 farms.
Procedures—Data on age at calving for primiparous cows and mature equivalent milk yield for multiparous cows, assistance at calving, stillbirths, twin births, gestation duration, pregnancy at the end of the data collection period, and culling-death for all cows were extracted from farm computer records and used for statistical analysis.
Results—Prevalence of twin parturitions was 1.3% (159/12,050) and 6.5% (1,410/21,818) for primiparous and multiparous cows, respectively. Primiparous and multiparous cows with singletons produced more milk than cows with live twins or at least 1 dead twin (primiparous, 33.1 vs 31.9 vs 31.2; multiparous, 36.5 vs 35.7 vs 35.0). Multiparous cows with dead twins produced less milk than cows with live twins. Compared with dams with singleton birth, cows with twins were 0.78 times as likely to conceive and 1.42 times as likely to die or be culled. Cows with dead twins also had increased time to conception, compared with live twins.
Conclusions and Clinical Relevance—Twin birth was associated with decreased survival, milk production, and reproductive performance. Having at least 1 dead twin was even more detrimental than having live twins and resulted in decreased milk production and reproductive performance of lactating cows.
Objective—To compare agreement between 2 pregnancy tests in dairy cattle.
Animals—976 and 507 cattle for phases 1 and 2, respectively.
Procedures—Blood samples were collected, and palpation per rectum (PPR) was performed on cattle. Blood samples for the pregnancy-specific protein B (PSPB) ELISA were sent by courier to a commercial laboratory with results returned later. Results of PPR were extracted from herd records. Statistical comparison of results was performed by use of a mixed linear model and N analysis.
Results—Of 571 cattle classified as pregnant by the PSPB ELISA in phase 1, 30 (5%) were nonpregnant by PPR. Mean ± SE adjusted optical density (OD) of cattle classified pregnant by both tests was significantly higher (0.31 ± 0.01), compared with the adjusted OD of cattle classified pregnant by the PSPB ELISA and nonpregnant by PPR (0.22 ± 0.02). Of 255 cows classified pregnant by the PSPB ELISA in phase 2, 31 (12%) were nonpregnant by PPR. Mean ± SE adjusted OD of cattle classified pregnant by both tests was significantly higher (0.26 ± 0.01), compared with the adjusted OD of cattle classified pregnant by the PSPB ELISA and nonpregnant by PPR (0.21 ± 0.01). The N value was 0.82 and 0.81 for phases 1 and 2, respectively.
Conclusions and Clinical Relevance—Good agreement existed between the 2 tests, especially at longer intervals after insemination. Discrepant results appeared to be attributable to a nonviable fetus, embryonic loss, or fetal loss.
Objective—To describe the occurrence of fecal shedding,
persistence of shedding over time, and
serogroup classification of Salmonella spp on a large
number of dairy farms of various sizes.
Sample Population—22,417 fecal samples from cattle
and 4,570 samples from the farm environment on
110 organic and conventional dairy farms in
Minnesota, Wisconsin, Michigan, and New York.
Procedure—5 visits were made to each farm at 2-month intervals from August 2000 to October 2001.
Fecal samples from healthy cows, calves, and other
targeted cattle groups and samples from bulk tank
milk, milk line filters, water, feed sources, and pen
floors were collected at each visit. Bacterial culture
was performed at 1 laboratory.
Results—Salmonella spp were isolated from 4.8% of
fecal samples and 5.9% of environmental samples;
92.7% of farms had at least 1 Salmonella-positive sample.
The 75th percentile for median within-herd prevalence
of Salmonella spp in cattle for 5 sampling visits to
a given farm was 2.0% and for maximum within-herd
prevalence of Salmonella spp was 13.6%. Farms with
a median within-herd prevalence of Salmonella spp of
≥ 2.0% accounted for 76.3% of Salmonella-positive
samples. There was no significant difference in the
prevalence of Salmonella spp between conventional
and organic farms. Seasonal differences in Salmonella
shedding were observed. More farms had at least 1
serogroup B isolate than any other serogroup, whereas
serogroup E1 was the most common among all
Salmonella-positive samples. More than 1 serogroup
was isolated on 76.4% of Salmonella-positive farms.
Conclusions and Clinical Relevance—Salmonella
spp were isolated from > 90% of dairy farms; however,
25% of farms accounted for > 75% of
Salmonella-positive samples. This information is critical
for the direction of intervention strategies to
decrease the prevalence of Salmonella spp on dairy
farms. (J Am Vet Med Assoc 2004;225:567–573)