Prevalence of antimicrobial resistance among Salmonella on midwest and northeast USA dairy farms

The objective of this study was to determine the prevalence of antimicrobial resistance among Salmonella isolated from dairy herds in New York, Minnesota, Michigan, and Wisconsin, USA. Serogroup and antimicrobial susceptibility characteristics were determined for Salmonella from cattle and environmental samples collected during August 2000–October 2001 as part of a longitudinal study where 129 herds were visited at 2-month intervals. Salmonella isolates were tested (using a broth microdilution method) for susceptibility to amoxicillin/clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Of the 1506 isolates tested for minimum inhibitory concentrations to these 14 antimicrobial agents, 81.2% were pan-susceptible and for most herds (81.6%) the predominant antimicrobial resistance pattern was pan-susceptible. At least 1 Salmonella isolate resistant to 5 or more antimicrobial agents was found on 23.6% of herds. This resistance phenotype was most common among serogroups B and E1 and among samples from calves and farmer-designated sick cows. Resistant samples most frequently exhibited resistance to tetracycline, streptomycin, and/or ampicillin. No samples were resistant to ceftriaxone (though 13 were in the intermediate range), and very few samples were resistant to ciprofloxacin (n = 1), nalidixic acid (n = 5), or trimethoprim/sulfamethoxazole (n = 7).     

Ulnocarpal arthrodesis in a cat

A nine-year-old cat was presented with non-weight-bearing lameness of the right forelimb subsequent to an old fracture of the antebrachium previously treated by external stabilisation. Radiography showed severe atrophic non-union of the distal third of the radius and carpal luxation. Ulnocarpal arthrodesis was performed using a uniplanar external fixator. Follow-up radiography showed that bone fusion was slow but without complication. After 16 weeks, the external fixator was removed, and a Robert-Jones bandage was applied for one month. From postoperative week 2 onwards, the animal progressively made use of the limb in a weight-bearing capacity. At the last examination, one year postoperative, no lameness was observed.     

Clinical, humoral and IFNgamma responses of cattle to infection with Mycoplasma mycoides var. mycoides small colony and attempts to condition the pathogenesis of the infection

Contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides var. mycoides small colony (MmmSC), is one of the most important diseases of cattle in Africa. The role of innate or acquired cell mediated and humoral immunity in conferring protection against MmmSC infection has not yet been elucidated. On the other hand, the pathological lesions caused by the aetiological agent have been considered indicative of an immunopathological process. In this study ten na?ve cattle were exposed to in-contact infection with animals infected by intubation with a strain of MmmSC. Clinical signs, antibody response, IFNgamma release and pathological changes at necropsy were analysed and compared with the events following in-contact infection of an equal number of animals kept under daily treatment with cyclosporine for the entire observation period of 84 days. Cyclosporine is a suppressor of the immune response related to the T-cell system. Under the conditions of the experiment, cyclosporine appeared to condition the pathogenesis of CBPP by delaying the events that follow infection, bringing further support to the possibility that the immune response may have an impact on the disease outcome.     

Extracellular heat shock protein 70 levels in tumour-bearing dogs and cats treated with radiation therapy and hyperthermia

Hyperthermia is a form of a cancer treatment which is frequently applied in combination with radiotherapy (RT) to improve therapy responses and radiosensitivity. The mode of action of hyperthermia is multifactorial; the one hand by altering the amount of the blood circulation in the treated tissue, on the other hand by modulating molecular pathways involved in cell survival processes and immunogenic interactions. One of the most dominant proteins induced by hyperthermia is the major stress-inducible heat shock protein 70 (Hsp70). Hsp70 can be found in the blood either as a free-protein (free HSP70) derived from necrotic cells, or lipid-bound (liposomal Hsp70) when it is actively released in extracellular vesicles (EVs) by living cells. The aim of the study was to evaluate the levels of free and liposomal Hsp70 before and after treatment with RT alone or hyperthermia combined with radiotherapy (HTRT) in dogs and cats to evaluate therapy responses. Peripheral blood was collected from feline and canine patients before and at 2, 4, 6 and 24 h after treatment with RT or HTRT. Hsp70 enzyme-linked immunosorbent assays (ELISAs) were performed to determine the free and liposomal Hsp70 concentrations in the serum. The levels were analysed after the first fraction of radiation to study immediate effects and after all applied fractions to study cumulative effects. The levels of free and liposomal Hsp70 levels in the circulation were not affected by the first singular treatment and cumulative effects of RT in cats however, after finalizing all treatment cycles with HTRT free and liposomal Hsp70 levels significantly increased. In dogs, HTRT, but not treatment with RT alone, significantly affected liposomal Hsp70 levels during the first fraction. Free Hsp70 levels were significantly increased after RT, but not HTRT, during the first fraction in dogs. In dogs, on the other hand, RT alone resulted in a significant increase in liposomal Hsp70, but HTRT did not significantly affect the liposomal Hsp70 when cumulative effects were analysed. Free Hsp70 was significantly induced in dogs after both, RT and HTRT when cumulative effects were analysed. RT and HTRT treatments differentially affect the levels of free and liposomal Hsp70 in dogs and cats. Both forms of Hsp70 could potentially be further investigated as potential liquid biopsy markers to study responses to RT and HTRT treatment in companion animals.     

Genetic and non-genetic factors influencing KLH binding natural antibodies and specific antibody response to Newcastle disease in Kenyan chicken populations

This study aimed at investigating the influence of genetic and non-genetic factors on immune traits to inform on possibilities of genetic improvement of disease resistance traits in local chicken of Kenya. Immune traits such as natural and specific antibodies are considered suitable indicators of an individual's health status and consequently, used as indicator traits of disease resistance. In this study, natural antibodies binding to Keyhole Limpet Hemocyanin (KLH-NAbs) was used to measure general disease resistance. Specific antibodies binding to Newcastle disease virus (NDV-IgG) post vaccination was used to measure specific disease resistance. Titers of KLH-NAbs isotypes (KLH-IgM, KLH-IgG and KLH-IgA) and NDV-IgG were measured in 1,540 chickens of different ages ranging from 12 to 56 weeks. A general linear model was fitted to determine the effect of sex, generation, population type, phylogenetic cluster, line, genotype and age on the antibody traits. A multivariate animal mixed model was fitted to estimate heritability and genetic correlations among the antibody traits. The model constituted of non-genetic factors found to have a significant influence on the antibody traits as fixed effects, and animal and residual effects as random variables. Overall mean (±SE) concentration levels for KLH-IgM, KLH-IgG, KLH-IgA and NDV-IgG were 10.33 ± 0.04, 9.08 ± 0.02, 6.00 ± 0.02 and 10.12 ± 0.03, respectively. Sex, generation and age (linear covariate) significantly (p < 0.05) influenced variation across all the antibody traits. Genotype effects (p < 0.05) were present in all antibody traits, apart from KLH-IgA. Interaction between generation and line was significant (p < 0.05) in KLH-IgM and NDV-IgG while nesting phylogenetic cluster within population significantly (p < 0.05) influenced all antibody traits, apart from KLH-IgA. Heritability estimates for KLH-IgM, KLH-IgG, KLH-IgA and NDV-IgG were 0.28 ± 0.08, 0.14 ± 0.06, 0.07 ± 0.04 and 0.31 ± 0.06, respectively. There were positive genetic correlations (0.40–0.61) among the KLH-NAbs while negative genetic correlations (−0.26 to −0.98) were observed between the KLH-NAbs and NDV-IgG. Results from this study indicate that non-genetic effects due to biological and environmental factors influence natural and specific antibodies and should be accounted for to reduce bias and improve accuracy when evaluating the traits. Subsequently, the moderate heritability estimates in KLH-IgM and NDV-IgG suggest selection possibilities for genetic improvement of general and specific immunity, respectively, and consequently disease resistance. However, the negative correlations between KLH-NAbs and NDV-IgG indicate the need to consider a suitable approach that can optimally combine both traits in a multiple trait selection strategies.     

Alfalfa (Medicago sativa L.) water use efficiency as affected by harvest traffic and soil compaction in a sandy loam soil

Summary Traffic during alfalfa harvest operations can cause soil compaction and damage to newly growing stems. Root exploration for soil water and nutrients, forage growth dynamics, and final yield can all be affected. The objectives of this study were to determine the long-term effects of harvest traffic and soil compaction on water-use efficiency (WUE) of alfalfa grown in a Wasco sandy loam (coarse-loamy, mixed, nonacid, thermic Typic Torriorthents). Alfalfa was planted into tilled soil and managed with or without harvest traffic. Plants subjected to traffic during harvest had a significantly lower WUE two out of the three years studied compared to plants that were never subject to traffic. The second experiment examined whether planting alfalfa into compacted soil and managed with or without harvest traffic altered WUE. Soil compaction had no affect on alfalfa WUE. It was significantly lower when grown in compacted soil and subjected to harvest traffic. It is suggested that the decrease in WUE caused by harvest traffic may be explained by plants allocating carbohydrates to damaged shoots and crowns instead of to above ground forage production. The area of the field affected by harvest traffic, which damages newly growing stems, should be minimized to increase crop water use efficiency.