Efficacy of non-antibiotic treatment options for digital dermatitis on an organic dairy farm.

The objective of this study was to evaluate the efficacy of two non-antibiotic treatment options for digital dermatitis (DD) on an organic certified dairy farm. A randomized clinical trial was conducted using 70 multiparous Holstein cows with an early DD lesion at a USDA certified organic dairy farm in Northern Colorado, USA. Cows were enrolled in the study based on the presence of early DD lesions (scores M1 and M2) and randomly assigned to one of three treatments: (1) topical application of copper sulfate and iodine (CUI); (2) topical application of honey and iodine (HOI); and (3) control subject to no treatment (CON). Cows were evaluated at enrolment and on days 3, 12, 28, and 120 post treatment for pain and lesion size and received a locomotion and a lesion score. Cure was defined as the transition from active to non-active stages (M1/M2 to M0 or M4). The formulations had variable effects on the treatment of DD. The cure rate was numerically higher for CUI on all follow up days. The proportion of cows experiencing pain on d3 after treatment was greater in CON, followed by HOI and CUI. However, this proportion increased in HOI during the follow up period. The CUI group had a greater reduction in lesion size and larger lesions persisted in HOI. Non-antibiotic treatment formulations were partially effective in the treatment of DD in organic dairy cows: The two non-antibiotic formulations resulted in an earlier transition to mature lesions compared with the control group. The CUI combination was the most effective treatment in reducing lesion size, pain, and lameness in affected cows. However, this combination had short-term efficacy, which did not persist throughout the duration of the study. The HOI combination produced only transient reduction in lesion size.

Pharmacokinetics of chlortetracycline in maternal plasma and in fetal tissues following oral administration to pregnant ewes.

The purpose of this study was to determine if concentrations of chlortetracycline could be detected in fetal plasma or tissues after administering an oral dose of chlortetracycline (CTC; 500 mg/head/day) reported to be effective in controlling Campylobacter spp. abortions. Five pregnant ewes were administered 250 mg/head twice a day (total dose 500 mg/hd/d) for 7 days. On the beginning of day 7, intravenous catheters were surgically implanted or inserted into the fetus and dam. Plasma samples were collected from the ewe and fetus at various time points before and up to 36 hr after the last dose of CTC. All ewes were then sacrificed, and tissues were harvested from the fetus for drug analysis. Concentrations of CTC in maternal plasma were consistent with our previous study and below the minimum inhibitory concentration of Campylobacter abortion isolates. Concentrations of CTC were below the limit of detection in three of five fetal plasma samples and all of the placenta, amniotic fluid, and fetal stomach contents. Low concentrations were detectable in fetal kidney and liver, suggesting that CTC reaches the fetus, although at a variable and low ratio when compared to maternal concentrations.

Risk of exposure to Coxiella burnetii from ruminant livestock exhibited at Iowa agricultural fairs.

Coxiella burnetii is a zoonotic pathogen typically associated with clinical and asymptomatic infection in ruminant livestock. A re-emerging pathogen of significant public health importance, C. burnetii has caused recent epidemics in the United States and Europe, and public livestock exhibitions are increasingly scrutinized as a potential source of C. burnetii exposure. Although C. burnetii prevalence data among North American domestic ruminants are extremely limited, contemporary studies suggest that this pathogen is both geographically widespread and highly prevalent on a herd basis, especially in dairy cattle and goat populations. We utilized a real-time PCR assay to detect C. burnetii faecal shedding by clinically normal, non-periparturient beef cattle, meat goats and sheep exhibited at Iowa agricultural fairs. Individual faecal samples were collected from beef cattle, meat goats and sheep exhibited at twelve Iowa county fairs during the summer of 2009. The sample pool was blocked by species and fair, and ten samples from each block were randomly selected for the diagnostic assay; this test pool is considered sufficient to identify with 95% confidence a shedding animal in a population prevalence of 2.85% (cattle and sheep) and 6.25% (goats). Detection of C. burnetii DNA was determined through use of a real-time PCR assay validated for use in bovine, ovine and caprine faeces; threshold of detection is one DNA copy per PCR (sensitivity 95.8%, specificity 100%). All tested samples were negative for C. burnetii DNA. We conclude that non-dairy, non-periparturient ruminants exhibited at Iowa fairs are unlikely to shed C. burnetii in their faeces and that this population should not be considered to be a significant exposure risk to other livestock or fair attendees.

Missing pieces of the puzzle to effectively control digital dermatitis.

Since the first report of bovine digital dermatitis (DD) in 1974, there is a large body of the literature published; however, effective prevention and control of the disease remain elusive. Although many aspects of the pathogenesis of DD have been investigated, even some of the most basic questions such as the aetiology of this disease remain under debate. Treponema spp. have been strongly associated with DD lesions and occur in abundance in advanced lesions; however, efforts to induce disease with pure cultures of these organisms have been largely underwhelming and inconsistent. Furthermore, although the disease has been presented for several decades, there is limited scientific evidence regarding effective treatment of DD. Apparent discrepancies between effectiveness in vitro and in vivo have challenged the scientific community to identify new potential treatment options. With no treatment resulting in a 100% cure rate, the current expectation is manageable control, but prospects for the eradication of the disease are unlikely using current approaches. In order to develop more effective approaches to control DD on-farm, there is a critical need for a deeper understanding regarding the causation, ecology, transmission and treatment of this disease. In this article, we attempt to provide insights into specific research needs related to DD in order to assist the industry, researchers, pharmaceutical companies and research sponsors with decision-making and identified research gaps.

Pharmacokinetics of oral chlortetracycline in nonpregnant adult ewes.

The objectives of this study were to determine plasma concentrations and pharmacokinetic parameters of feed-grade chlortetracycline (CTC) in sheep after oral administration of 80 or 500 mg/head daily, divided into two equal doses given at 12-h intervals for 8 days. These are the approved, and commonly used but unapproved, feed additive doses, respectively, in the United States for the prevention of ovine infectious abortion. Blood samples were collected just prior to dosing at 0, 12, 24, 72, 96, and 192 h, as well as 4, 8, 12, 24, and 36 h after the last dose, and noncompartmental pharmacokinetic analysis was performed to estimate elimination half-life and area under the plasma concentration-time curve (AUC). Mean observed maximum CTC concentrations (Cmax ) were 20.0 ng/mL (80 mg dose) and 101 ng/mL (500 mg dose). Mean apparent elimination half-life was 18 h (80 mg dose) and 20 h (500 mg dose). Although published data do not exist to estimate plasma CTC concentrations necessary for the prevention of ovine infectious abortion, concentrations reached in our study suggest that either the FDA-approved and FDA-unapproved dosages are not high enough or that the pharmacodynamic parameter relating preventive dose to pathogen minimum inhibitory concentrations is yet to be determined.

Expression of toll-like receptors 2 and 4 in subplacental trophoblasts from guinea pigs (Cavia porcellus) following infection with Campylobacter jejuni.

Toll-like receptors 2 and 4 (TLR2 and TLR4) are well-characterized cell surface receptors that recognize specific pathogen-associated molecular patterns and play an important role in pathogen recognition and activation of the innate immune system. Variable expression of TLR2 and TLR4 has been described in trophoblasts from normal and diseased placentas; yet, there are limited data regarding trophoblast TLR expression in response to specific placental pathogens, and TLR expression in the guinea pig placenta has not been described. The guinea pig is an effective model for Campylobacter-induced abortion of small ruminants, and the authors have shown by immunohistochemistry that C jejuni localizes within syncytiotrophoblasts of the guinea pig subplacenta. The present study was designed to determine if the expression of either TLR2 or TLR4 would be affected in subplacental trophoblasts following infection with C jejuni. Immunohistochemistry for TLR2 and TLR4 was performed on placenta from guinea pigs that aborted following inoculation with C jejuni and from sham-inoculated controls. Quantitative assessment of TLR expression was performed, and mean immunoreactivity for TLR2 was significantly higher in subplacental trophoblasts from animals that aborted compared with uninfected controls (P = .0283), whereas TLR4 expression was not statistically different (P = .5909). These results suggest that abortion in guinea pigs following infection with C jejuni is associated with increased TLR2 expression in subplacental trophoblasts and may reveal a possible role for TLR2 in the pathogenesis of Campylobacter-induced abortion.

A randomized and blinded field trial to assess the efficacy of an autogenous vaccine to prevent naturally occurring infectious bovine keratoconjunctivis (IBK) in beef calves.

A randomized and blinded 2-arm parallel trial was conducted to assess the efficacy of an autogenous vaccine to prevent naturally occurring infectious bovine keratoconjunctivis (IBK) in beef calves. The trial was managed between May and November 2008 on university owned farms in Iowa and Wisconsin. The vaccine at Iowa contained Moraxella bovoculi (M. bovoculi) while the organism used in the Wisconsin herds vaccine was Branhemella ovis (B. ovis renamed M. ovis). Calves born between January and May 2008 without visible corneal lesions were randomized to receive an autogenous vaccine or placebo vaccine using a computer generated sequence. Two subcutaneous doses were administered 21-28 days apart. Allocation to treatment was concealed using bottles marked A or B. Staff were blind to the treatment allocation. The primary outcome was IBK cumulative incidence over the study period. The secondary outcome was weaning weight. Only the Iowa herd met the criteria for an "at-risk" herd i.e. >15% IBK in unvaccinated calves and M. bovoculi isolation from IBK cases. Analysis was "per-protocol". The cumulative incidence of IBK was 47/105 in vaccinated calves and 49/109 in unvaccinated calves (unadjusted odds ratio=0.99, 95% CI: 0.58-1.70). Weight at weaning did not differ between the vaccinated cohort 148kg (SD: +/-27) and unvaccinated cohort 146kg (SD: +/-26) (unadjusted beta=1.5 and 95% CI: -5.5 to 8.6). Results indicate that the autogenous vaccine was ineffective in this study population.

Fecal shedding of feline coronavirus in adult cats and kittens in an Abyssinian cattery.

OBJECTIVE: To determine patterns of fecal shedding of feline coronavirus (FCV) by cats, age at which kittens first began to shed FCV in their feces, and whether there was any relationship between fecal shedding of FCV and serum antibody titers in adult cats or kittens. DESIGN: Prospective observational study. ANIMALS: 15 adult cats and 18 kittens from a single cattery. PROCEDURE: Blood and fecal samples were collected from adult cats every other month for 13 months. Serum FCV antibody titers were measured by use of an indirect immunofluorescence assay. A reverse-transcriptase, nested polymerase chain reaction assay was used to detect FCV in feces. Blood and fecal samples were collected from kittens at approximately 2-week intervals from 3 weeks to 15 weeks of age. RESULTS: Adult cats shed FCV intermittently. All adult cats shed virus in their feces at least once during the year, and 4 of 15 shed virus > 75% of the time. Serum antibody titer was not significantly associated with shedding of FCV. For the kittens, median age at the time FCV was first detected in feces was 67 days (range, 33 to 78 days). All except 1 of the kittens was found to be shedding virus in their feces before or at the time of seroconversion. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that serum FCV antibody titers are not a good indicator of shedding of FCV in the feces. Kittens may shed FCV in their feces before they seroconvert, and all kittens in a cattery in which FCV infection is endemic may be infected before 12 weeks of age.

Detection of duck enteritis virus by polymerase chain reaction.

Duck enteritis virus (DEV), a herpesvirus, is the causative agent of duck viral enteritis in free-flying, feral, and domesticated members of the Anatidae family. HindIII-digested DEV DNA was cloned into the plasmid pBluescript, and a 1.95-kb fragment was sequenced. This fragment codes for the 3' region of the DEV homologues of varicella-zoster virus (VZV) open reading frame (ORF) UL6 and the 5' region of VZV UL7. Alignment of the putative peptide fragments for DEV UL6 and UL7 showed a 64% and 37% identity with VZV UL6 and UL7, respectively. Primers located in the highly conserved domain of the UL6 gene were used for a polymerase chain reaction (PCR) assay, which was able to amplify DEV DNA. The PCR assay also amplified DEV DNA from the original outbreak samples and/or after passage in Muscovy duck embryos.

The Marihuana Perception Inventory: the effects of substance abuse instruction.

This article reports the latest results of a continuing effort to develop a perceptual inventory of factors associated with the onset of marihuana use among youths and young people. In addition to better understanding why adolescents begin using marihuana, the inventory is intended to assist drug educators target their programs. This phase studied 617 students in three Midwest school districts prior to and after substance abuse instruction to determine the relationship between perceptions and demographic characteristics, and to learn if substance abuse instruction was related to changes in the student's perception of the relationships. Factor analysis again revealed a five-factor solution. All thirty-four inventory items were included in the final solution. Items appeared to group themselves among the scales in a fashion similar to that found in prior studies. However, the larger sample size permitted refinement of the scales: Maturational Difficulties; Excessive Pressure; Parental Failings; Rebelliousness; and Societal/Institutional Weaknesses. The inventory appears to be remarkably stable across demographic characteristics. Significant differences between pretest and posttest scores indicated that students perceived less of a relationship between Maturational Difficulties, Excessive Pressure, and Societal/Institutional Weaknesses and the onset of marihuana use after instruction, and more of a relationship between Parental Failings and the young person's decision to begin using marihuana. It appears that instructional programs can be expected to at least contribute to changes in perceptions concerning the relationship between societal and familial factors and the onset of marihuana use.