Friday, February 18, 2011

Vancomycin-resistant bacteria in equine manure

Horses are not likely to play a major role in the spread of one type of antibiotic resistant micro-organism, to humans, according to a study in North West England.

Work reported at the International Conference on Antimicrobial Research in Valladolid in Spain November 2010 looked for vancomycin resistant enterococci (VRE) in equine faeces.

Lead researcher Dr Mohamed O Ahmed presented the results of the study, which looked at faecal samples from 66 hospitalised and 72 non-hospitalised horses.

Enterococci are enteric bacteria found in the digestive tract of many humans and animals. They may be responsible for urinary tract or wound infections (i.e. nosocomial infections). Also in patients with suppressed immune systems, they can cause serious conditions such as infection of the heart valves (endocarditis) and brain (meningitis).

Enterococci are naturally resistant to many antibiotics. One of the few last-choice antibiotics used for treating people with serious enterococcal infections is vancomycin.

Vancomycin-resistant enterococci is an emerging nosocomial organism, reportedly of zoonotic nature. There are several strains of vancomycin-resistant enterococci. The genes conferring resistance have probably been acquired from other types of bacteria that don't cause disease, but are already vancomycin resistant.

If specific vancomycin-resistant strains were present in horse faeces (i.e. VanA and VanB phenotypes) they could act as a zoonotic source of infection.

Overall, the researchers identified 47 suspected VRE isolates from a total of 264 faecal samples. Of those, only 9 were confirmed by polymerase chain reaction (PCR). Seven were confirmed as VanC genotype. Six of these were found in samples from hospitalised horses.

They identified one isolate each of VanA and VanD genotype. Both of these were in non-hospitalised horses, but neither could be typed by PCR.

The VanA genotype has been reported predominantly as the one involved in human infections. However, the VanC genotype, which was found most frequently in this study, is not commonly isolated in cases of human infection.

The researchers conclude that it is unlikely that horses play a major role in the transmission of VRE to humans in that specific geographic area. Also, the fact that most of the VRE isolates were found in hospitalised horses, suggests that hospitalisation could increase the risk of transmission between horses and possibly to humans too. Future research may be needed to look into this.


Thursday, February 10, 2011

Study finds whipping racehorses pointless

Whipping has no effect on the likelihood of a horse winning or being placed, according to a recent report. The authors conclude that whipping tired horses in the name of sport is very difficult to justify.

Dr David Evans and Professor Paul McGreevy based their findings on the horses’ speed, the number of times they were whipped and their place in the field. The information was gathered from five sprint races (over 1200-1250 meters) at the racetrack at Canterbury, New South Wales. 

“When we compared the sectional times 600-400m, 400-200m, 200m – finish, horses ran fastest in the 600-400m section, during which no horses were whipped”  Dr Evans explained. “Horses achieved their highest speeds during the last 600m of the races without being whipped.”

 “Increased whip use was most frequent in the final two 200 metre sections when horses were fatigued.''

“Analysis of the data showed that the strongest predictor of racing success was where a horse was placed at the 400m and 200m marks. Neither whip counts in the final 400m or 200m, nor velocity in the final 200m, significantly explained the probability of finishing 1st, 2nd or 3rd,” Prof McGreevy added.

“That said, it remains possible that whip use in the final stages of a race really does improve relative performance at a stage when all horses are slowing, but more frequent and sensitive methods of measuring velocity may be required to detect such a cause and effect linkage.” 

The authors conclude, “These data make whipping tired horses in the name of sport very difficult to justify.”

For more details see:

Tuesday, February 08, 2011

Equine Guelph survey research

Equine Guelph offer you the chance to influence their research and education programs so they meet the needs of the equine industry. 

Complete their survey and you can enter a draw for one of two gift certificates for an Equine Guelph online course of your choice (valued at $549.00) 

Mistletoe for treating equine sarcoids?

 Could a festive winter decoration provide the cure for equine sarcoids?

Sarcoids are the most common skin tumour of horses. They are difficult to treat, and may recur after treatment.  A new therapeutic option has been suggested by a Swiss study, which found that an extract of mistletoe was an effective treatment.

The findings have been reported in the Journal of Veterinary Internal Medicine. Lead author was Ophélie Christen-Clottu of the Research Institute of Organic Agriculture, Frick, Switzerland.

The study compared the response of sarcoids to treatment with an aqueous extract* of the pine mistletoe (Viscum album ssp. austriacus) and a placebo.

Mistletoe contains compounds, like lectins and viscotoxins that have been shown experimentally to have cytotoxic and growth inhibiting properties and immune modulating activity. Extracts are used as an adjunct to treatment of cancer in human medicine.

The treatment consisted of injections of 1ml of mistletoe extract in increasing concentrations (from 0.1mg/ml to 20mg/ml) administered 3 times a week for 15 weeks. Control animals were injected with 1ml of saline at similar intervals.

The researchers monitored the location, number, and type of sarcoids present for a year after the start of the study. Neither they nor the horse owners knew which horses were treated with the mistletoe preparation or the placebo until the end of the study.

Fifty-three horses, with a total of 444 sarcoid lesions, were treated - with either mistletoe extract or placebo. Forty-two horses were treated as monotherapy and 11 horses were treated with mistletoe extract or placebo after selective surgical excision of some sarcoids.

Five of the treated horses developed mild oedema at the site of injection when the higher concentration injections were given. This swelling disappeared within a few days without treatment.   No other adverse effects were noted.

At the end of the study, sarcoids were no longer visible in 9 of 32 mistletoe extract treated horses and 3 of 21 placebo control horses. This difference was not statistically significant. However, another 4 horses in the VAE group showed reduction in more than half of the sarcoids.

So, overall, 41% of horses in the treatment group showed complete or partial regression of the sarcoids - which was significantly different from the response in the placebo group.

The curative effects were higher in verrucous sarcoids than by other types of sarcoids. On advantage of VAE treatment is the systemic effect: if treatment is successful, all tumors of one horse can regress. The disadvantage of the therapy was  that response to treatment was slow - being seen only after the end of the 15 week treatment period in many cases.

They conclude that mistletoe extract proved effective for treating clinically diagnosed equine sarcoid in this study. They suggest that it can be recommended particularly when excision may not be appropriate, for example for sarcoids around the eyes or for cases with multiple sarcoids.


Striving to prevent foal pneumonia

News that a vaccine against Rhodococcus equi is entering the final stages of development offers the hope of preventing this serious respiratory condition of foals.

R equi causes chronic broncho-pneumonia with abscesses in the lungs, typically affecting foals less than six months old. Other forms of the disease occur including infection of the intestine and lymph nodes.

Rhodococcus equi does not only infect horses. It is an opportunistic human pathogen associated with diseases that result in suppression of the immune system.

The organism is found in soil, especially in the presence of horse faeces, which provides the substrate on which it feeds. It is well equipped to resist desiccation. Foals are infected by inhaling contaminated dust.

Treatment is difficult. The organism is resistant to many common antibiotics. It lives within the macrophages, making it difficult for antibiotics to reach it.  A long course of suitable antibiotics - such as erythromycin and rifampin - is required to effect a cure.

As yet there is no effective vaccine. However, on January 27, 2011, Intervet / Schering-Plough Animal Health announced that a vaccine against Rhodococcus equi infection in foals was entering the final stages of development.

The vaccine is based on a special non-pathogenic strain of the bacterium. Four genes have been deleted from its genome, to make the bacterium incapable of causing disease, but still able to stimulate immunity.

Preliminary studies have shown that the genetically modified strain is safe, and unable to cause disease in foals as well as in calves chickens, pigs rats and mice.

Approval has now been given for field trials to commence. These will start shortly in Germany. In the first phase of the study, a group of foals will be vaccinated with the candidate vaccine and will be compared to a group of non-vaccinated foals. The number of R equi infections will be evaluated in each group.

An effective vaccine against R equi would be a great step forward in the control of this disease.