Multilaboratory Survey To Evaluate Salmonella Prevalence in Diarrheic and Nondiarrheic Dogs and Cats in the United States between 2012 and 2014.

Eleven laboratories collaborated to determine the periodic prevalence of Salmonella in a population of dogs and cats in the United States visiting veterinary clinics. Fecal samples (2,965) solicited from 11 geographically dispersed veterinary testing laboratories were collected in 36 states between January 2012 and April 2014 and tested using a harmonized method. The overall study prevalence of Salmonella in cats (3 of 542) was <1%. The prevalence in dogs (60 of 2,422) was 2.5%. Diarrhea was present in only 55% of positive dogs; however, 3.8% of the all diarrheic dogs were positive, compared with 1.8% of the nondiarrheic dogs. Salmonella-positive dogs were significantly more likely to have consumed raw food (P = 0.01), to have consumed probiotics (P = 0.002), or to have been given antibiotics (P = 0.01). Rural dogs were also more likely to be Salmonella positive than urban (P = 0.002) or suburban (P = 0.001) dogs. In the 67 isolates, 27 unique serovars were identified, with three dogs having two serovars present. Antimicrobial susceptibility testing of 66 isolates revealed that only four of the isolates were resistant to one or more antibiotics. Additional characterization of the 66 isolates was done using pulsed-field gel electrophoresis and whole-genome sequencing (WGS). Sequence data compared well to resistance phenotypic data and were submitted to the National Center for Biotechnology Information (NCBI). This study suggests an overall decline in prevalence of Salmonella-positive dogs and cats over the last decades and identifies consumption of raw food as a major risk factor for Salmonella infection. Of note is that almost half of the Salmonella-positive animals were clinically nondiarrheic.

The Effect of Copper and Zinc Sources on Liver Copper and Zinc Concentrations and Performance of Beef Cows and Suckling Calves.

To determine the influence of the source of gestational and postnatal Cu and Zn supplementation on cow and calf performance, cows (n = 287) were assigned to one of the following two treatments: (1) inorganic (INORG) treatment, in which cows were supplemented with 15 mg of Cu (as CuSO4) and 15 mg of Zn (as ZnSO4) per kg of diet DM, or (2) organic (ORG) treatment, in which cows were supplemented with 15 mg of Cu (as Cu proteinate; Bioplex Cu, Alltech, Inc., Nicholasville, KY, USA) and 15 mg of Zn (as Zn proteinate; Bioplex Zn, Alltech, Inc., Nicholasville, KY, USA) per kg of diet DM. The treatments were initiated prior to breeding and continued throughout gestation until weaning. Liver biopsies were collected for analysis of mineral content. Cow body condition score (BCS), body weight (BW), pregnancy data, calf weaning weight (WW), and antibody response of the calves were recorded. The cows receiving the INORG treatment had a greater BW (p < 0.05) and BCS (p < 0.01) at breeding in Year 2, while the cows on the ORG treatment had a greater (p < 0.05) BW at weaning in Year 2. The cows that received the ORG mineral had improved (p < 0.05) conception rates in Year 1. The calves receiving the ORG treatment had heavier (p < 0.05) 205-day adjusted WWs.

Influenza A(H1N1)pdm09 virus among healthy show pigs, United States.

Within 5 months after the earliest detection of human influenza A(H1N1)pdm09 virus, we found molecular and culture evidence of the virus in healthy US show pigs. The mixing of humans and pigs at swine shows possibly could further the geographic and cross-species spread of influenza A viruses.

A pre-pandemic outbreak of triple-reassortant swine influenza virus infection among university students, South Dakota, 2008.

BACKGROUND: After identifying a student with triple-reassortant swine influenza virus (SIV) infection and pig exposure at a livestock event, we investigated whether others were infected and if human-to-human transmission occurred. METHODS: We conducted a cohort study and serosurvey among persons exposed to (1) event pigs, (2) other pigs, (3) the index case, and (4) persons without pig or index case exposure. Confirmed cases had respiratory specimens positive for SIV within 2 weeks of the index case's illness. Probable and suspected cases had illness and (1) exposure to any pig or (2) contact with a confirmed case preceding illness. Probable cases were seropositive. Suspected cases did not give serum samples. RESULTS: Of 99 event pig-exposed students, 72 (73%) participated in the investigation, and 42 (42%) provided serum samples, of whom 17 (40%) were seropositive and 5 (12%) met case criteria. Of 9 students exposed to other pigs, 2 (22%) were seropositive. Of 8 index case-exposed persons and 10 without exposures, none were seropositive. Pig-exposed persons were more likely to be seropositive than persons without pig exposure (37% vs 0%, P < .01). CONCLUSIONS: We identified an outbreak of human SIV infection likely associated with a livestock event; there was no evidence of human-to-human transmission.

Seroprevalence of Brucella canis in dogs rescued from South Dakota Indian reservations, 2015-2019.

Canine brucellosis, caused by Brucella canis, is an infectious disease with implications for canine as well as human health. The identification of infected dogs originating from and around two South Dakota Indian reservations prompted an examination of the seroprevalence of B. canis in stray or owner-surrendered dogs from these communities. Using results from in-clinic screening tests of 3898 dogs over more than 4 years, we determined an overall apparent B. canis seroprevalence of 6.8% (adjusted estimated true prevalence of 29.4%), with rates declining over time. The apparent rate was similar to other surveys of stray dog populations in the US. Older dogs were significantly more likely to be B. canis-positive than younger dogs, as were reproductively intact dogs versus altered dogs (although this difference was not statistically significant). There were geographic differences in seropositive rates as well, with higher rates found in dogs originating from one reservation compared to other locations. Current diagnostic tests lack sensitivity to effectively identify all B. canis-infected dogs, but results from this study are valuable for investigating differences among risk factors for infection. Because of the potential for B. canis to infect other dogs and people, stray dog populations should be screened for B. canis before those animals are placed in adoptive homes.

Cattle and carcass performance, and life cycle assessment of production systems utilizing additive combinations of growth promotant technologies.

The objective of this study was to determine the impact of beef production systems utilizing additive combinations of growth promotant technologies on animal and carcass performance and environmental outcomes. Crossbred steer calves (n =120) were stratified by birth date, birth weight, and dam age and assigned randomly to one of four treatments: 1) no technology (NT; control), 2) antibiotic treated (ANT; NT plus therapeutic antibiotics and monensin and tylosin), 3) implant treated (IMP; ANT plus a series of 3 implants, and 4) beta-agonist treated (BA; IMP plus ractopamine-HCl for the last 30 d prior to harvest). Weaned steers were fed in confinement (dry lot) and finished in an individual feeding system to collect performance data. At harvest, standard carcass measures were collected and the United States Department of Agriculture (USDA) Yield Grade and Quality Grade were determined. Information from the cow-calf, growing, and finishing phases were used to simulate production systems using the USDA Integrated Farm System Model, which included a partial life cycle assessment of cattle production for greenhouse gas (GHG) emissions, fossil energy use, water use, and reactive N loss. Body weight in suckling, growing, and finishing phases as well as hot carcass weight was greater (P < 0.05) for steers that received implants (IMP and BA) than non-implanted steers (NT and ANT). The average daily gain was greater (P < 0.05) for steers that received implants (IMP and BA) than non-implanted steers during the suckling and finishing phases, but no difference (P = 0.232) was detected during the growing phase. Dry matter intake and gain:feed were greater (P < 0.05) for steers that received implants than non-implanted steers during the finishing phase. Steers that received implants responded (P < 0.05) with a larger loin muscle area, less kidney pelvic and heart fat, advanced carcass maturity, reduced marbling scores, and a greater percentage of carcasses in the lower third of the USDA Choice grade. This was offset by a lower percentage of USDA Prime grading carcasses compared with steers receiving no implants. Treatments did not influence (P > 0.05) USDA Yield grade. The life cycle assessment revealed that IMP and BA treatments reduced GHG emissions, energy use, water use, and reactive nitrogen loss compared to NT and ANT. These data indicate that growth promoting technologies increase carcass yield while concomitantly reducing carcass quality and environmental impacts.

Outbreak of Salmonella enterica serotype Newport in a beef cow-calf herd associated with exposure to bovine viral diarrhea virus.

CASE DESCRIPTION: Severe disease and death in cows and calves affected 1 of 3 separate groups (A, B, and C) of cattle on a commercial cow-calf operation. CLINICAL FINDINGS: Clinical illness consisting of severe watery and bloody diarrhea, dehydration, weakness, and death affected adult cows and calves in 1 group (group B). Salmonella enterica serotype Newport was recovered from tissues of cows and calves from group B. TREATMENT AND OUTCOME: Despite supportive and antimicrobial treatment of cattle in group B, cow mortality rate attributable to salmonellosis in that group was 7.9% (32/407); calf mortality rate was 14.4% (52/361). None of the cows in Groups A or C died, and the calf mortality rate in those groups was low. Salmonella enterica serotype Newport was recovered from pooled fecal samples subsequently collected from each group of cows. Bovine viral diarrhea virus (BVDV) antigen was identified in an ear notch sample collected from a necropsied calf from group B. Subsequently, ear notch specimens from cattle in all 3 groups were tested for BVDV antigen. A significantly higher proportion of calves persistently infected with BVDV was identified in group B (8/295 [2.7%]), compared with the proportion in groups A and C combined (1/287 [0.3%]). CLINICAL RELEVANCE: Outbreaks of disease attributable to Salmonella Newport infection in beef cattle are unusual. Because of the immunosuppressive nature of BVDV, the possibility of animals persistently infected with BVDV within the herd should be considered during investigation of unusual outbreaks of infectious diseases.

Case-control study to determine herd-level risk factors for bovine respiratory disease in nursing beef calves on cow-calf operations.

OBJECTIVE To determine herd-level risk factors for bovine respiratory disease (BRD) in nursing beef calves. DESIGN Matched case-control study. SAMPLE 84 cow-calf operations in Nebraska, North Dakota, and South Dakota. PROCEDURES Case herds were herds that treated at least 5% of the calf crop for BRD prior to weaning. Control herds were herds that treated < 0.5% of the calf crop for BRD prior to weaning. Each case herd was matched with 2 control herds on the basis of veterinary practice and enrollment year. Herd owners or managers were interviewed by telephone, and characteristics and practices associated with case status were determined by multivariable conditional logistic regression. RESULTS 30 case herds and 54 control herds were evaluated. Increasing herd size, frequent pasture movement for intensive grass management (intensive grazing), and use of estrus-synchronization programs were significantly associated with herd status. The odds of being a case herd for herds with 150 to 499 cows was 7.9 times and that for herds with ≥ 500 cows was 12 times, compared with the odds of being a case herd for herds with < 150 cows. The odds of being a case herd for herds that used intensive grazing was 3.3 times that for herds that did not use intensive grazing. The odds of being a case herd for herds that used an estrus-synchronization program was 4.5 times that for herds that did not use an estrus-synchronization program. CONCLUSIONS AND CLINICAL RELEVANCE Management practices can be associated with an increase in the BRD incidence in nursing beef calves. Modification of management practices may decrease BRD incidence in nursing calves for herds in which it is a problem.

Beef producer survey of the cost to prevent and treat bovine respiratory disease in preweaned calves.

OBJECTIVE To estimate costs associated with prevention and treatment of bovine respiratory disease (BRD) in preweaned calves on US beef cow-calf operations. DESIGN Cross-sectional survey. SAMPLE 43 beef cow-calf producers whose operations had a history of BRD in preweaned calves. PROCEDURES Mail and electronic surveys were developed and administered to producers in Nebraska, North Dakota, and South Dakota to obtain information regarding costs of BRD prevention and treatment. Descriptive statistics were generated. Mixed linear regression models were used to assess factors associated with the costs of vaccines, medicine, and labor and percentage time spent on prevention and treatment of BRD in cows, replacement heifers, and preweaned calves. RESULTS 7 mail and 36 electronic surveys were completed. Median annual costs for BRD vaccines were $2.25, $4.00, and $6.25/animal, and median annual labor costs for vaccination were $4.58, $3.00, and $5.00/animal for cows, heifers, and preweaned calves, respectively. Median annual costs for medicine and labor to treat preweaned calves for BRD were $11.00 and $15.00/ affected calf, respectively. Adjusted mean annual BRD vaccine cost for preweaned calves ($7.67/animal) was significantly greater than that for cows ($3.18/animal) and heifers ($4.48/animal). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that labor costs associated with BRD vaccination and treatment were similar to or exceeded the cost of vaccines and medicine, and most of those labor costs were associated with gathering and sorting cattle. Therefore, costs associated with labor as well as medicine and vaccines should be considered during the development of BRD prevention and treatment plans.

Bovine herpesvirus 1 modified live virus vaccines for cattle reproduction: Balancing protection with undesired effects.

Bovine herpesvirus 1 (BoHV-1) has long been associated with reproductive failure in cattle following infection of the ovary and/or fetus. Vaccination prior to breeding has been an effective approach to lessen the impact of BoHV-1 on reproduction. Prior studies in the 1980s and 1990s established the susceptibility of the ovary and particularly the corpus luteum (CL) to BoHV-1 infection. A series of studies at breeding time established that: (1) in naïve animals, the CL was the major target of BoHV-1 pathology; (2) CL lesions occurred within 4-9 days after estrus; (3) similar lesions was seen with BoHV-1 MLV vaccines; (4) ovarian lesions varied by the vaccine strain used; (5) progesterone decreased with or without CL lesions; and (6) following reactivation of BoHV-1 latent infection, ovaries could become reinfected in the face of BoHV-1 immunity. Large scale field studies demonstrated that conception was highest in animals previously vaccinated and boostered with inactivated vaccine compared to animals revaccinated with MLV. In the early 2000s, to get a label claim to vaccinate calves nursing pregnant cows, safety study outlines were approved by USDA-APHIS CVB. These studies were designed to determine the effect of revaccination with MLV during pregnancy on previously vaccinated cows and were not rigorous enough to confirm complete fetal safety. As designed these studies showed no difference in reproductive loss between the previously vaccinated animals and the animals revaccinated ∼4, 7 and 9 months later, leading to the label approval for MLV vaccination in pregnant cows. Subsequent investigations by diagnostic laboratories found an increase in BoHV-1 reproductive loss after the approval for use in pregnant animals. A method was developed to differentiate IBR vaccine strains from field strains. Analysis of viruses from 31 cases from 2009-2016 indicated that all 31 isolates matched with vaccine strains. Going forward, it will be necessary to develop vaccine approaches that use non-abortifacient, nonlatent BoHV-1 vaccines that develop lifelong immunity, protecting the animal while doing no harm to the fetus.

Effects of preovulatory estradiol on embryo survival and pregnancy establishment in beef cows.

The role of preovulatory estradiol on post-fertilization embryo survival and pregnancy establishment has not been well characterized in beef cows. We hypothesized that preovulatory estradiol is important for embryo survival and pregnancy establishment in beef cows. Twenty-four ovariectomized multiparous cows were used in a replicated 3×3 Latin Square design. Cows received estradiol cypionate (ECP) 36h, estradiol benzoate (EB) 12h, or no estradiol (CON) before a gonadotropin-releasing hormone (d 0) induced LH surge. Luteal phase progesterone was mimicked with twice daily progesterone injections from d 3 to 6. On d 7 cows received one embryo and progesterone was supplemented with progesterone-releasing devices (CIDR). Expression of interferon stimulated genes, ISG15, MX2, and OAS1, in leukocytes was determined on d 17, 19, 21, and 28 to determine capability of embryonic signaling. Pregnancy specific protein B concentrations were measured in serum samples from d 17 through 29 to determine embryonic attachment. Transrectal ultrasonography was performed on d 29 and 32 to determine pregnancy viability (heartbeat). Serum estradiol profiles during simulated proestrus/estrus were different (P<0.001) between treatments. Mean serum progesterone concentrations from d 17 to 24 were decreased (P=0.05) in EB and ECP cows compared to CON. Transrectal ultrasonography indicated that fewer CON (4%) cows had a viable embryo present compared to estradiol treated cows (25%). Embryonic loss in cows that did not receive estradiol during the simulated preovulatory period occurred following maternal recognition of pregnancy, indicating that its impact was likely on uterine receptivity and embryonic attachment.

The effects of vaccination on serum hormone concentrations and conception rates in synchronized naive beef heifers.

Crossbred beef heifers (N = 59) were vaccinated at the time of synchronization/breeding with either a commercially available bovine herpesvirus type 1 modified live virus (MLV) (one dose) or inactivated virus vaccine (one or two doses). The estrus cycle was synchronized at vaccination and heifers were artificially inseminated 8 days (one dose) or 36 days (two dose) after initial vaccination. Pregnancy rates were greater for control heifers (90%; P = 0.02) and heifers given the inactivated virus vaccine (one dose: 86%; P = 0.08; or two: 90%; P < 0.01) than those given the MLV vaccine (48%). No control heifers experienced an abnormal estrous cycle, whereas only two (two dose; 2/21) and one (one dose; 1/7) heifers in the inactive virus groups had abnormal estrous cycles and were similar to control (P > 0.10). Heifers given the MLV vaccine had a greater (P = 0.02) percentage of abnormal estrous cycles (38%; 8/21) compared with the control and inactivated groups. Of the heifers with an abnormal estrous cycle, 100% of heifers given the inactivated vaccine (one or two dose) conceived at their return estrus, whereas only 38% of heifers given the MLV vaccine conceived at their return estrus (P > 0.10). During the synchronization period, concentrations of estrogen were greater (P < 0.01) in the control and the two-dose inactivated group compared with the MLV group. After AI, progesterone concentrations were greater (P < 0.01) in control heifers compared with the inactivated and MLV groups, but were similar (P ≥ 0.18) between the inactivated and MLV groups. Therefore, naïve heifers vaccinated with the inactivated vaccine were less likely to have an abnormal estrous cycle and had significantly higher pregnancy rates compared with heifers vaccinated with the MLV vaccine. In summary, vaccination of naïve heifers with an MLV vaccine at the start of a fixed-time AI protocol had a negative effect on pregnancy success.

Attitudes toward becoming a veterinarian in a group of undergraduate agriculture and biomedical sciences students.

OBJECTIVE: To assess the level of interest of university students enrolled in veterinary science courses toward becoming a veterinarian, reasons supporting or discouraging their interest, when those attitudes were formed, and future plans for those pursuing veterinary medicine as a career. DESIGN: Cross-sectional study. SAMPLE: 585 university students in South Dakota enrolled in 2 veterinary science courses over a 6-year period. PROCEDURES: Each year, students enrolled in the 2 courses answered survey questions pertaining to their interest in becoming a veterinarian, background, and future plans. RESULTS: Most students enrolled in these courses desired to become a veterinarian at some time in their lives. Females were more likely than males to indicate veterinary medicine as their current career choice. Most students developed their interest during grades 10 to 12. Females developed an interest in veterinary medicine earlier than did males. Enjoyment of animals, intellectual stimulation, and the opportunity to actively work outdoors were cited frequently as reasons for interest in veterinary medicine. Increased duration of education, high educational costs, and preveterinary coursework difficulty were major reasons for disinterest in becoming a veterinarian. Of students pursuing the profession, desired practice type correlated strongly with previous animal experience. CONCLUSIONS AND CLINICAL RELEVANCE: Considering that most students, especially males, developed their interest in veterinary medicine during grades 10 to 12, elementary school may be the best starting point for exposing students to veterinary medicine. To increase interest in large animal practice among students entering veterinary school, livestock experiences should be provided to children with no farm experience during their elementary, middle, and high school years. In our survey population, cost and duration of veterinary education had a significant negative influence on student interest in the profession.

Development of genetic markers in the non-structural protein 2 region of a US type 1 porcine reproductive and respiratory syndrome virus: implications for future recombinant marker vaccine development.

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to be a major problem in the pork industry worldwide. The limitations of current PRRSV vaccines require the development of a new generation of vaccines. One of the key steps in future vaccine development is to include markers for diagnostic differentiation of vaccinated animals from those naturally infected with wild-type virus. Using a cDNA infectious clone of type 1 PRRSV, this study constructed a recombinant green fluorescent protein (GFP)-tagged PRRSV containing a deletion of an immunogenic epitope, ES4, in the nsp2 region. In a nursery pig disease model, the recombinant virus was attenuated with a lower level of viraemia in comparison with that of the parental virus. To complement the marker identification, GFP and ES4 epitope-based ELISAs were developed. Pigs immunized with the recombinant virus lacked antibodies directed against the corresponding deleted epitope, but generated a high-level antibody response to GFP by 14 days post-infection. These results demonstrated that this recombinant marker virus, in conjunction with the diagnostic tests, enables serological differentiation between marker virus-infected animals and those infected with the wild-type virus. This rationally designed marker virus will provide a basis for further development of PRRSV marker vaccines to assist with the control of PRRS.