Antimicrobial susceptibility of Salmonella and Escherichia coli from equids sampled in the NAHMS 2015-16 equine study and association of management factors with resistance.

Several studies have investigated antimicrobial resistance (AMR) in Salmonella spp. and Escherichia coli isolated from hospitalized horses, but studies conducted on community-based populations of equids are limited. The factors associated with AMR in these bacteria in the general horse population are not well understood. The primary objective of our study was to estimate the prevalence of Salmonella and describe antimicrobial susceptibility of Salmonella and E. coli from equids across the United States. The second objective was to identify associations between health management and biosecurity practices and AMR. Fecal samples submitted from 1357 equids on 199 operations were tested for Salmonella, identifying 27 positive samples with 29 isolates belonging to 18 serotypes. Fecal sample and operation-level prevalence of Salmonella was 2.0% (27/1357) and 7.0% (14/199), respectively. Most (25/29) isolates were pan-susceptible while four isolates exhibited resistance, three of which were multidrug resistant. Of the 721 samples cultured for E. coli, 85% (613/721) were positive. Eighty-six percent of the E. coli isolates recovered were pan-susceptible (529/612). Ten isolates were intermediate to one antimicrobial drug and susceptible to all others. Seventy-three E. coli isolates (11.9%, SE=1.3) were resistant to one or more antimicrobials, corresponding to a 33.0% (64/194) operation-level prevalence. Resistance to sulfonamide drugs was most common with 63 isolates (10.3%) resistant to sulfisoxazole, 57 of which (9.3%) were resistant to trimethoprim-sulfamethoxazole. MDR in E. coli was rare (1.8%, SE=0.5). Univariate and multivariable regression were used to evaluate associations between health management and biosecurity questionnaire items and AMR in E. coli. The outcome modeled was resistance to any of the 14 tested antimicrobials. Depending on the operation type, operations with greater than 20 resident equids were significantly associated with resistance. In addition, performance operations were significantly associated with resistance when compared to farm/ranch operations. Operations with feed containers that prevent fecal contamination and those that had treated any equids for illness or injury were associated with a lower AMR. The study results suggest that equids in the general population appear to pose low risk of shedding antimicrobial resistant strains of Salmonella and E. coli, and therefore low transmission potential to other equids, animals, humans, or the environment. However, it is prudent to practice good hand hygiene to prevent spread of Salmonella as well as AMR, and to protect both animal and human health. Despite study limitations, potential management factors that may influence prevalence and prevent spread of AMR shed by equids were identified.

The National Animal Health Monitoring System's perspective on respiratory disease in dairy cattle.

In 1991, USDA's National Animal Health Monitoring System (NAHMS) conducted its first dairy study, a baseline assessment that focused on the health and management of heifer calves. During the study, producers ranked respiratory disease among the top two most common health problems affecting dairy calves. Over the last 25 years, U.S. dairy producers have participated in six NAHMS studies, yielding a rich repository of information that has helped identify needs for research, extension, and education in the dairy industry. NAHMS' most recent dairy study, conducted in 2014, provides the latest estimates on dairy cattle health and includes another in-depth look at heifer-calf health. While overall mortality in calves has decreased, bovine respiratory disease (BRD) remains an important cause of morbidity in calves. This raises the concern that BRD mitigation may be at a standstill on dairies. Research and on-farm experience have done much to elucidate the challenges associated with detection and perceived impacts of this complex disease. Continued development and implementation of new methods for monitoring health and detecting disease will provide additional tools to upend stalemating factors associated with BRD control, helping the dairy industry 'turn a corner' on this important disease.

Comparative composition, diversity, and abundance of oligosaccharides in early lactation milk from commercial dairy and beef cows.

Prebiotics are nondigestible dietary ingredients, usually oligosaccharides (OS), that provide a health benefit to the host by directly modulating the gut microbiota. Although there is some information describing OS content in dairy-source milk, no information is available to describe the OS content of beef-source milk. Given the different trait emphasis between dairy and beef for milk production and calf survivability, it is plausible that OS composition, diversity, and abundance differ between production types. The goal of this study was to compare OS in milk from commercial dairy and beef cows in early lactation. Early-lactation multiparous cows (5-12 d in milk) from 5 commercial Holstein dairy herds and 5 Angus or Angus hybrid beef herds were sampled once. Milk was obtained from each enrolled cow and frozen on the farm. Subsequently, each milk sample was assessed for total solids, pH, and OS content and relative abundance. Oligosaccharide diversity and abundance within and between samples was transformed through principal component analysis to reduce data complexity. Factors from principal component analysis were used to create similarity clusters, which were subsequently used in a multivariate logistic regression. In total, 30 OS were identified in early-lactation cow milk, including 21 distinct OS and 9 isomers with unique retention times. The majority of OS detected in the milk samples were present in all individual samples regardless of production type. Two clusters described distribution patterns of OS for the study sample; when median OS abundance was compared between the 2 clusters, we found that overall OS relative abundance was consistently greater in the cluster dominated by beef cows. For several of the structures, including those with known prebiotic effect, the difference in abundance was 2- to 4-fold greater in the beef-dominated cluster. Assuming that beef OS content in milk is the gold standard for cattle, it is likely that preweaning dairy calves are deprived of dietary-source OS. Although supplementing rations with OS is an approach to rectify this deficiency, understanding the health and productivity effects of improving OS abundance being fed to preweaning calves is a necessary next step before recommending supplementation. These studies should account for the observation that OS products are variable for both OS diversity and structural complexity, and some products may not be suitable as prebiotics.

Recent Emergence of Escherichia coli with Cephalosporin Resistance Conferred by blaCTX-M on Washington State Dairy Farms.

Enterobacteriaceae-associated blaCTX-M genes have become globally widespread within the past 30 years. Among isolates from Washington State cattle, Escherichia coli strains carrying blaCTX-M (CTX-M E. coli strains) were absent from a set of 2008 isolates but present in a set of isolates from 2011. On 30 Washington State dairy farms sampled in 2012, CTX-M E. coli prevalence was significantly higher on eastern than on northwestern Washington farms, on farms with more than 3,000 adult cows, and on farms that recently received new animals. The addition of fresh bedding to calf hutches at least weekly and use of residual fly sprays were associated with lower prevalence of CTX-M E. coli. In Washington State, the occurrence of human pathogens carrying blaCTX-M genes preceded the emergence of blaCTX-M-associated E. coli in cattle, indicating that these resistance determinants and/or their bacterial hosts may have emerged in human populations prior to their dissemination to cattle populations.

Serial gastrointestinal ultrasonography following exploratory celiotomy in normal adult ponies.

The objective was to characterize ultrasonographic changes in bowel wall thickness, contractility, degree of distension, luminal contents, and peritoneal fluid associated with exploratory celiotomy in normal ponies. Gastrointestinal ultrasonographic examination was performed in 14 ponies on days 1, 3, 5, and 7 after an exploratory celiotomy. Wall thickness, contractility, degree of distension, and luminal contents were recorded for the duodenum and jejunum. Stomach wall thickness and location, cecal wall thickness, and peritoneal fluid location and character were recorded. Peritoneal fluid was identified most frequently on day 1 (P = 0.0005). Duodenal wall thickness was significantly decreased on day 7 compared with days 1, 3, and 5 suggesting inflammatory thickening postoperatively (P = 0.005). Stomach wall thickness was decreased on day 1 compared with days 3, 5, and 7 (P = 0.03). All measurements, however, were within normal limits. Hypocontractile segments of jejunum were most frequently identified on day 1 (P = 0.02) and hypoechoic contents were identified most frequently in the jejunum on day 1 and the duodenum on day 3, suggesting mild functional ileus or enteritis in the early postoperative period. Our findings support that bowel handling during abdominal exploration causes minimal changes in bowel wall thickness, contractility, degree of distension, luminal contents, and peritoneal fluid. This study was performed in ponies without gastrointestinal disease and further studies are necessary in patients.

Gastrointestinal ultrasonography in normal adult ponies.

The objective of this study was to determine the characteristics based on ultrasonographic examination of the stomach, duodenum, jejunum, cecum, and peritoneal fluid in normal adult ponies. Abdominal ultrasonographic examination was performed in nine unsedated standing ponies. The duodenum was examined at three sites and the jejunum in 12 regions. Wall thickness, contractility, distention, and luminal contents were recorded. Stomach wall thickness and location, cecal wall thickness, and peritoneal fluid location and character were recorded. Statistical analysis was performed. Wall thicknesses (in cm) were 0.431 +/- 0.069 for the stomach, 0.188 +/- 0.033 for the duodenum (at all sites), 0.195 +/- 0.031 for the jejunum (at all regions), and 0.179 +/- 0.031 for the cecum. Duodenal contractions per minute were 3.78 +/- 1.10. The stomach spanned 5.14 +/- 0.9 intercostal spaces, with the 8th intercostal space being the most cranial and the 15th intercostal space being the most caudal space through which the stomach was identified. It was possible to identify the jejunum in all ponies dorsal to the left dorsal colon and from the ventral abdominal wall. Peritoneal fluid was identified in six ponies. Peritoneal fluid was usually seen transiently and most commonly in the ventral aspect of the abdominal cavity or around the duodenum. Overall, the ponie's abdominal ultrasonographic examinations revealed wall thicknesses that were less than the published normal ranges for horses. It appears that ponies may have increased duodenal contractility than horses and that the conformation of ponies may change the locations for imaging the stomach.

Eastern equine encephalitis in 9 South American camelids.

BACKGROUND: Eastern equine encephalitis (EEE) virus is a mosquito-borne togavirus (alphavirus) that causes severe (often fatal) encephalitis in many mammalian species, but it has not been reported previously in South American camelids. HYPOTHESIS: South American camelids can become naturally infected with EEE virus and show encephalitic signs similar to those observed in other affected species. ANIMALS: Nine cases (8 alpacas and 1 llama, aged 3.5 weeks to 12 years) were identified; 4 of 9 were 510 weeks old. All cases were from the East Coast of the United States and presented in late summer and fall. METHODS: A retrospective study was performed to include confirmed cases of EEE in camelids in North America before 2006. RESULTS: Eight of nine (89%) camelids died or were euthanized in extremis, with the mean time to death of 2 days. Clinical signs were consistent with encephalitis and included fever, lethargy, ataxia, seizures, recumbency, torticollis, opisthotonus, and vestibular signs. No consistent hematologic abnormalities were identified, and cerebrospinal fluid contained an increased protein concentration in the single camelid analyzed. No successful therapy was identified. EEE was confirmed by alphavirus detection by using immunohistochemistry (IHC) and polymerase chain reaction (PCR) in the central nervous system (CNS) and by serology. Findings included polioencephalitis with lymphocytic perivascular cuffing; neutrophil infiltration; gliosis; neuron satellitosis; necrosis; and edema, with intracytoplasmic alphavirus within neurons and glial cells. No virus was detected in extraneural tissues. CONCLUSIONS AND CLINICAL IMPORTANCE: In endemic areas, EEE should be considered a differential diagnosis for young and adult camelids with CNS disease. Brain histopathology with indirect IHC or PCR is diagnostic.