There is increasing interest in exploiting natural products as feed additives to solve problems in animal nutrition and livestock production. Essential oils and saponins are two types of plant secondary compounds that hold promise as natural feed additives for ruminants. This paper describes recent advances in research into these additives. The research has generally concentrated on protein metabolism. Dietary essential oils caused rates of NH 3 production from amino acids in ruminal fluid taken from sheep and cattle receiving the oils to decrease, yet proteinase and peptidase activities were unchanged. Hyper-ammonia-producing (HAP) bacteria were the most sensitive of ruminal bacteria to essential oils in pure culture. Essential oils also slowed colonisation and digestion of some feedstuffs. Ruminobacter amylophilus may be a key organism in mediating these effects. Saponin-containing plants and their extracts appear to be useful as a means of suppressing the bacteriolytic activity of rumen ciliate protozoa and thereby enhancing total microbial protein flow from the rumen. The effects of some saponins seems to be transient, which may stem from the hydrolysis of saponins to their corresponding sapogenin aglycones, which are much less toxic to protozoa. Saponins also have selective antibacterial effects which may prove useful in, for example, controlling starch digestion. These studies illustrate that plant secondary compounds, of which essential oils and saponins comprise a small proportion, have great potential as 'natural' manipulators of rumen fermentation, to the potential benefit of the farmer and the environment.

The objective of this systematic review, which was performed following the guidelines of the Cochrane collaboration, was to assess the effects of interventions for treatment of atopic dermatitis (AD) in dogs. Citations identified from three databases (MEDLINE, Thomson’s Science Citation Index Expanded and CAB Abstracts) and trials published by December 2007 were selected. Proceedings books from the major veterinary dermatology international congresses were hand searched for relevant citations. The authors selected randomized controlled trials (RCTs), published from January 1980 to December 2007, which reported the efficacy of topical or systemic interventions for treatment or prevention of canine AD. Studies had to report assessments of either pruritus or skin lesions, or both. Studies were selected and data extracted by two reviewers, with discrepancies resolved by a third arbitrator. Missing data were requested from study authors of recently published trials. Pooling of results and meta‐analyses were performed for studies reporting similar interventions and outcome measures. A total of 49 RCTs were selected, which had enrolled 2126 dogs. This review found some evidence of efficacy of topical tacrolimus (3 RCTs), topical triamcinolone (1), oral glucocorticoids (5), oral ciclosporin (6), subcutaneous recombinant γ‐interferon (1) and subcutaneous allergen‐specific immunotherapy (3) to decrease pruritus and/or skin lesions of AD in dogs. One high‐quality RCT showed that an oral essential fatty acid supplement could reduce prednisolone consumption by approximately half. Additional RCTs of high design quality must be performed to remedy previous flaws and to test interventions for prevention of flares of this disease.

Staphylococcal colonization was compared in healthy dogs and in dogs with atopic dermatitis. Bacterial swabs were collected from the nasal mucosa, ear and perineum of 43 healthy and 24 atopic dogs and also from potentially infected skin lesions of the atopic dogs. Coagulase positive staphylococcal isolates were identified to the species level. At the time of this study Staphylococcus intermedius was considered a single species but has since been recognized as comprising at least three species with canine isolates believed to belong to Staphylococcus pseudintermedius. Of atopic dogs, 87.5% were colonized with S. intermedius compared to only 37.2% of healthy dogs. The ear was the only carriage site that showed any significant difference in S. intermedius isolation between healthy and atopic dogs. The perineum represented the most frequently colonized mucosal site for both groups. Sampling the nasal mucosa alone identified 71.4% of atopic and 37.5% of healthy S. intermedius carriers. Inclusion of a perineal swab identified 100% of atopic and 93.8% of healthy carriers. S. intermedius was isolated from all the lesional sites sampled from atopic dogs. Significantly fewer dogs were colonized by Staphylococcus aureus than S. intermedius, and there was no significant difference between S. aureus colonization of atopic and healthy dogs. S. aureus was not recovered from any lesions in atopic dogs. The results show that S. intermedius carriage is more prevalent in atopic dogs compared to healthy dogs and that to identify staphylococcal carriers both the nasal mucosa and the perineum should be sampled.

Based on complete bacterial genome sequence data, we demonstrate a correlation between bacterial chromosome length and the G+C content of the genome, with longer genomes having higher G+C contents. The correlation value decreases at shorter genome sizes, where there is a wider spread of G+C values. However, although significant (P<0.001), the correlation value (Pearson R=0.58) suggests that other factors also have a significant influence. A similar pattern was seen for plasmids; longer plasmids had higher G+C values, although the large number of shorter plasmids had a wide spread of G+C values. There was also a significant (P<0.0001) correlation between the G+C content of plasmids and the G+C content of their bacterial host. Conversely, the G+C content of bacteriophages tended to reduce with larger genome sizes, and although there was a correlation between host genome G+C content and that of the bacteriophage, it was not as strong as that seen between plasmids and their hosts.