No benefit in metformin IR study

A study into the pharmacological management of insulin resistance using metformin, failed to demonstrate any benefit.

The research was conducted by the School of Animal and Veterinary Sciences, Charles Sturt University in New South Wales, Australia and the Department of Clinical Studies, New Bolton Centre, University of Pennsylvania, PA, USA, in collaboration with the Waltham Equine Studies Group. Lead researcher was PhD candidate Kellie Tinworth.

In insulin resistance, insulin seems unable to exert its normal effect. This is particularly noticeable in relation to glucose metabolism. As a result, the body releases increasing amounts of insulin, ending up with normal or raised blood glucose levels despite high concentrations of insulin.

Insulin resistance appears to be a significant risk factor for conditions such as laminitis.

Therefore, it is important to prevent IR from developing, or to manage it before it contributes in turn to the development or progression of other potentially life-threatening conditions.

While the correct management of energy intake and exercise levels is thought to be essential, in some cases medication is also considered, especially when increased exercise is not possible.

No licensed drugs are currently available for treating insulin resistance in horses and ponies. Metformin has been suggested as a possible treatment for the condition. It appears to enhance insulin sensitivity of peripheral tissues without stimulating insulin secretion.

The research team hoped to confirm that metformin had a positive effect on insulin and glucose dynamics in insulin-resistant ponies, so that it could be used as a positive control in other studies.

Six ponies that were insulin-resistant, but not obese, took part in the study. Three ponies were allocated to the treatment group, and they received metformin (at 15mg/kg bodyweight orally, twice daily) for 21days. The control group received a placebo.

After a "wash out" period, the trial was repeated with the ponies being swapped between the treatment and placebo groups.

The response to metformin (and the placebo) was assessed using a frequently-sampled intravenous glucose tolerance test (FSIGT).
 
The researchers found no measurable benefits of metformin. No significant change was noted in any of the indices of insulin sensitivity. Neither was there any change in bodyweight, body condition score or cresty neck score.

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Role of bacteria in periodontal disease

Bacteria may be more important in the development of periodontal disease in horses than previously thought, according to research carried out at the University of Edinburgh.

Equine periodontal disease is a common condition in horses affecting around 60 percent of horses over the age of 15 years. The disease is painful and can have a big impact on a horse's quality of life, affecting the animal's ability to eat and its performance.

Bacteria are known to be a cause of periodontal disease in humans, cats and dogs, but it is less clear what role they play in the disease in horses. Mechanical factors, such as food being packed between the horse's teeth due to abnormal growth and spaces have been considered to be the primary cause.

Research, carried out by Alistair Cox, is believed to be the first to describe the microscopic anatomy of equine periodontal disease.

Cox examined the skulls of 22 horses that had been submitted for post mortem examination. Although none of the horses had received treatment for periodontal disease, 16 had some form of periodontal disease.

"This research, funded by The Horse Trust, highlights how common periodontal disease is in horses. Yet many horses don't receive treatment so are likely to be suffering in silence. I would advise all horse owners to get their vet or equine dentist to regularly check their horse to see if it is developing the condition," he said.

Cox identified bacteria, including spirochaetes, that were associated with periodontal disease. Spirochaetes are known to be important in human and canine periodontal disease, but this is the first study to identify them in association with the condition in horses.

"This study shows that bacteria may be more important than was previously thought in the development of equine periodontal disease,” said Cox

"More research is needed to understand whether bacteria or mechanical factors are the main cause of the disease. Once we have a better understanding of why and how the disease develops, we can do more to prevent horses from developing this painful condition."

Read more at: http://www.equinescienceupdate.com/articles/rbpd.html

FIS test success

One year on, the test for Fell Pony Syndrome, has been acclaimed a great success.

As the genetic test identifies carrier animals, it can be used to prevent affected foals being conceived.  The disease only appears when both parents carry the mutation. Breeders can avoid producing affected foals by ensuring that they do not breed two carriers together.

Of the almost 1000 animals tested, 47% of Fell ponies and 10% of Dales ponies were found to carry the mutation for the disease.

The fatal disease is now known as Foal Immunodeficiency syndrome (FIS), as cases are not confined to one breed. Affected foals die or are euthanased, usually before they reach three months of age.  

Since February 2010, when the test became available, nearly 1000 samples have been tested. Three quarters of the samples came from Fell ponies. Of those tested, 47% of Fell ponies and 10% of Dales ponies were found to carry the mutation for FIS.

The test was developed as the result of research led by Dr June Swinburne of the Animal Health Trust, Newmarket. 

"This test, developed using funding from The Horse Trust, has been a massive success among the Fell and Dales pony breeding communities," she said. "We hope the test will prevent unnecessary suffering among Fell and Dales pony foals as breeders can now easily prevent the conception of foals with FIS. As so many breeders tested their breeding stock last year, we hope there will be very few foals affected by this horrendous disease in the future."

Read more at: http://www.equinescienceupdate.com/articles/fists.html

Does restricting grazing really reduce grass intake?

A recent study suggests that limiting access to pasture may not be effective at reducing grass intake by ponies

 

Recent research, about to be presented at a biannual nutrition meeting in the US, suggests that ponies given reduced access to pasture can eat considerable amounts of herbage during the time they are turned out. Indeed they may even increase their intake during this time as they become accustomed to the routine.

Intake of large amounts of fructan, and other rapidly fermentable carbohydrates by grazing ponies has been linked to the development of laminitis.  It has become common practice to restrict ponies’ access to pasture, especially at key times of the day/year in order to reduce the risk.

The study, which was conducted at the Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, in collaboration with the WALTHAM Equine Studies Group, aimed to investigate the effect of grazing restriction on herbage intake and grazing behaviour in ponies.

The grazing behaviour of eight ponies was measured daily over a six week period to assess their voluntary intake of herbage and to monitor the effects of restricting their access to pasture. Two groups of four pony mares were used. Group A had 24 hour access to pasture. The ponies in group B had three hours of pasture access daily and were stabled for the remaining 21 hours, with free access to haylage and water.

Herbage intake was estimated during the three hours when all the ponies were at pasture by monitoring the change in weight of each individual over the period. Grazing behaviour was analysed from video footage of the two groups using interval sampling. The ponies in the restricted grazing group had higher estimated grazed herbage intakes than those with 24 hour access to pasture .during the three hours studied. The difference was significant during the final week, when the restricted grazing group consumed 40% of their total daily dry matter intake as grass in the three hours at pasture. This compared with an intake of grass of around 25% of their daily dry matter ingested during the first week.

 

Clare Barfoot, research and development manager at SPILLERS®, said: “This suggests that ponies with reduced access to pasture are capable of ingesting considerable amounts of grass during the time they are turned out and may indeed progressively increase their intake during this time, indicating that the behaviour could be learned. The implication is that reducing ponies’ time out on normally managed pastures with the view to limiting the intake of rapidly fermentable carbohydrates may not be as effective as first thought.”

Reference:

Changes in proportions of dry matter intakes by ponies with access to pasture and haylage for 3 and 20 hours per day respectively for six weeks. 

 J. Ince,A. Longland,C. J. Newbold,P. Harris.  

Journal of Equine Veterinary Science (2011) (in press)