Vertical transmission of porcine circovirus type 2 in breeding herds

Porcine circovirus type 2 (PCV2) impacts global swine production, is economically important, and is associated with multiple disease entities that include multisystemic disease, wasting, pneumonia, diarrhea and reproductive failure. Transmission of PCV2 within or between swine populations is not well understood. We characterized semen shedding of PCV2a and PCV2b in Landrace boars and found that PCV2 viremia precedes semen shedding, clinical signs are absent, and peak PCV2 semen shedding occurs between 10-20 days post-infection. PCV2 can be continuously shed in semen for at least 90 days. We determined that PCV2 shed in semen is infectious when used in a swine bioassay model, but dam or fetal infection after artificial insemination with PCV2 positive extended semen does not necessarily occur. However, when nayve dams were artificially inseminated with PCV2-spiked semen, dam viremia and fetal infection occurred. Nayve dams inseminated with spiked semen did not show clinical signs of infection after PCV2 exposure, but increased numbers of mummified and stillborn fetuses were observed. Stillborn fetuses exhibited gross lesions of heart failure and myocardial tissue was determined to be the best sample for diagnosing in utero PCV2 infection. Using the PCV2-spiked semen model, we compared dam immunity associated with PCV2 vaccination to immunity associated with a previous infection to induce protection against subsequent PCV2-challenge. PCV2 antibodies induced by a homologous strain of PCV2 protected against in utero infection; however, 63% of the piglets from vaccinated dams were PCV2 viremic at birth suggesting that commercial vaccines may not prevent fetal infection. We also verified that PCV2 vaccination of dams is not protective against fetal infection following oro-nasal challenge during gestation, and affirmed that immunocompetent in utero fetuses are able to clear PCV2 infection prior to parturition

Effects of Label Dose Permethrin Use in Yearling Angus Beef Bulls on Reproductive Function and Testicular Histopathology

To eliminate the potential for insect borne diseases and improve productivity in cow-calf operations, many producers use pour-on pyrethroids. However, popular press literature has identified potential links between use of pyrethroids and reproductive function failures in bulls. While literature in mice and rats have reported potential endocrine disruption of sex steroids resulting from pyrethroid exposure, effects of pyrethroid use on bull fertility is still questionable. The objective of this study was to measure reproductive parameters in peripubertal Angus bulls using a commonly used pyrethroid pour-on. We hypothesized that use of a pyrethroid pour-on at labeled dose would have limited effects on semen and testicular characteristics. Results from this study revealed pyrethroid-treated bulls had greater spermatozoa head and midpiece abnormalities compared to controls, resulting in higher primary morphological abnormalities. Although some morphological semen parameters appear to be negatively affected by use of pyrethroid administration in bulls, biological relevance of this result needs to be further elucidated as the ability to pass a breeding soundness exam was not affected. Moreover, further research should be conducted to determine the effects of pyrethroid pour-ons on fertility when used with other pyrethroids such fly tags or perimeter sprays. Based on these results, pour-on pyrethroid use in yearling bulls is still recommended for label dose administration

Use of equine-origin antitoxins in piglets prior to exposure to mitigate the effects of Clostridium difficile infection – a pilot study

Administration to newborn pigs of an oral or intraperitoneal dose of equine-origin Clostridium difficile antitoxin 4 hours before orogastric inoculation with a swine-origin C difficile field isolate resulted in lower histopathology scores 72 hours post challenge than in pigs receiving no antitoxin (P \u3c .05)

Infectivity of porcine circovirus type 2 DNA in semen from experimentally-infected boars

Porcine circovirus type 2 (PCV2) is an economically important pathogen. It has been demonstrated that PCV2 DNA can be detected in boar semen by PCR; however, the biological relevance of this is unknown. The objectives of this study were to determine if semen positive for PCV2 DNA is infectious (1) in a swine bioassay, or (2) when used for artificial insemination. For the first objective, 4-week-old pigs were inoculated intraperitoneally with PCV2 DNA-negative (bioassay-control; n = 3), PCV2a DNA-positive (bioassay-PCV2a; n = 3), or PCV2b DNA-positive (bioassay-PCV2b; n = 3) raw semen, or PCV2 live virus (bioassay-positive; n = 3), respectively. Pigs inoculated with PCV2 DNA-positive semen and PCV2 live virus became viremic and developed anti-PCV2 antibodies indicating that the PCV2 DNA present in semen was infectious. For the second objective, three Landrace gilts were inseminated with PCV2 DNA-negative semen (gilts-controls) from experimentally-infected boars, and six gilts were artificially inseminated with semen positive for PCV2a DNA (gilts-PCV2a; n = 3) or PCV2b DNA (gilts-PCV2b; n = 3). Serum samples collected from the gilts in all groups remained negative for anti-PCV2 antibodies for the duration of the experiment. In addition, fetal serum samples from all 105-day-gestation fetuses were negative for anti-PCV2 antibodies or PCV2 DNA. Under the conditions of this study, PCV2 DNA-positive semen was not infectious when used to artificially inseminate gilts; however, it was demonstrated to be infectious in a swine bioassay model and therefore is a potential means of PCV2 transmission amongst swine herds

Survey of serum vitamin D status across stages of swine production and evaluation of supplemental bulk vitamin D premixes used in swine diets

The objectives of this investigation were to evaluate the serum 25-hydroxyvitamin D [25(OH)D] concentrations in pigs of different age groups, to determine if 25(OH)D concentrations varied with season, and to assess the quality of vitamin D supplements used in swine diets from multiple commercial suppliers. Serum samples (n = 1200) submitted to a diagnostic laboratory for routine surveillance were assayed for serum 25(OH)D concentrations. Vitamin D premix samples were obtained from suppliers and analyzed at two laboratories over a 9-month period. In all age categories, 25(OH)D concentrations in numerous serum samples were lower than reference values. In the nursery, finisher, and boar age categories, there was a difference between the months of January and June (P \u3c .05), with June samples containing higher quantities of circulating 25(OH)D. Serum samples from outdoor herds had higher 25(OH)D concentrations than samples from confined pigs (P \u3c .01). Among the supplement samples evaluated, no individual supplement had a concentration of 25(OH)D significantly lower than 500,000 IU per g. These results revealed that commercial swine may be deficient in serum vitamin D at varying times of the year, and feed-supplement concentrations may vary

Diagnostic assessment and lesion evaluation of chronic deoxynivalenol ingestion in growing swine

Deoxynivalenol (DON) is a common mycotoxin contaminant of cereal grains and is associated with reduced feed intake or refusal in swine. The objective of this assessment was to determine if diagnostic tests or lesions could assist in diagnosing chronic DON ingestion in swine. Twenty-four 11-week-old cross-bred pigs of both genders were fed either an ad libitum diet without deliberate contamination of DON (Control; n = 6) or a diet containing approximately 5 mg per kg DON (DON-fed; n = 18). Dried distillers’ grains with solubles were the source of DON for the diets. Serum analytes were measured at the beginning and conclusion of the 120-day study. All pigs were necropsied and liver analyte concentrations, bone density, and bone ash were determined. Differences in serum analyte concentrations, macroscopic or microscopic lesions, and bone ash and density were not detected between treatment groups (P \u3e .05). Liver selenium concentrations were lower (P = .02) in DON-fed pigs. Results suggest DON ingestion is not correlated with lesions or bone integrity, but can significantly lower liver selenium concentrations

Two clinical isolates of Mycoplasma hyosynoviae showed differing pattern of lameness and pathogen detection in experimentally challenged pigs

Mycoplasma (M.) hyosynoviae is known to colonize and cause disease in growing-finishing pigs. In this study, two clinical isolates of M. hyosynoviae were compared by inoculating cesarean-derived colostrum-deprived and specific-pathogen-free growing pigs. After intranasal or intravenous inoculation, the proportion and distribution pattern of clinical cases was compared in addition to the severity of lameness. Tonsils were found to be the primary site of colonization, while bacteremia was rarely detected prior to the observation of clinical signs. Regardless of the clinical isolate, route of inoculation, or volume of inocula, histopathological alterations and tissue invasion were detected in multiple joints, indicating an apparent lack of specific joint tropism. Acute disease was primarily observed 7 to 10 days post-inoculation. The variability in the severity of synovial microscopic lesions and pathogen detection in joint cavities suggests that the duration of joint infection may influence the diagnostic accuracy. In summary, these findings demonstrate that diagnosis of M. hyosynoviae-associated arthritis can be influenced by the clinical isolate, and provides a study platform to investigate the colonization and virulence potential of field isolates. This approach can be particularly relevant to auxiliate in surveillance and testing of therapeutic and/or vaccine candidates

Two clinical isolates of \u3ci\u3eMycoplasma hyosynoviae\u3c/i\u3e showed differing pattern of lameness and pathogen detection in experimentally challenged pigs

Mycoplasma (M.) hyosynoviae is known to colonize and cause disease in growing-finishing pigs. In this study, two clinical isolates of M. hyosynoviae were compared by inoculating cesarean-derived colostrum-deprived and specific-pathogen-free growing pigs. After intranasal or intravenous inoculation, the proportion and distribution pattern of clinical cases was compared in addition to the severity of lameness. Tonsils were found to be the primary site of colonization, while bacteremia was rarely detected prior to the observation of clinical signs. Regardless of the clinical isolate, route of inoculation, or volume of inocula, histopathological alterations and tissue invasion were detected in multiple joints, indicating an apparent lack of specific joint tropism. Acute disease was primarily observed 7 to 10 days post-inoculation. The variability in the severity of synovial microscopic lesions and pathogen detection in joint cavities suggests that the duration of joint infection may influence the diagnostic accuracy. In summary, these findings demonstrate that diagnosis of M. hyosynoviae-associated arthritis can be influenced by the clinical isolate, and provides a study platform to investigate the colonization and virulence potential of field isolates. This approach can be particularly relevant to auxiliate in surveillance and testing of therapeutic and/or vaccine candidates