Laminitis research: Even healthy older horses have increased insulin responses

New research, conducted in collaboration with the SPILLERS® horse feed company in Great Britain shows that even healthy older horses have increased insulin responses, compared to younger horses, in response to a starch-rich or starch- and sugar-rich meal.

Laminitis research: Feeding a high starch diet can influence PPID (Equine Cushings Disease) test results

Summary: New research, conducted in collaboration with the British horse feed company SPILLERS®, has shown that the equine diet, and more specifically, a starch rich food, can influence adrenocorticotropin hormone ,or ‘ACTH’, test results. This could potentially lead to an incorrect disease diagnosis in some horses when ACTH is used to test for Pituitary Pars Intermedia Dysfunction (PPID).

Key point: The threshold values for diagnosis of the disease currently vary dependent on the season, but these new findings suggest that diet should also be considered. 

Hoof Blog note: Laminitis in older horses is commonly blamed on PPID, but a definitive diagnosis by hormonal test results is required to determine if an underlying endocrine condition is the cause of laminitis. Some horses with PPID may lose weight, which might lead owners to increase feed or change to a higher-starch diet to counter weight loss. Horse owners and veterinarians should communicate about a horse's feed intake before testing; future research may reveal more specific guidelines about how feed type influences test results.

Laminitis Research: Feed Company SPILLERS Will Sponsor Two PhD Programs in 2015

Hoofcare Publishing is encouraging donations to laminitis research this holiday season. Right on cue, this press release arrived today with news of new support for program research in Great Britain. Thanks for Spillers for their continued support of laminitis research.

The British horse feed company SPILLERS®, as part of the WALTHAM® International Laminitis and Obesity Research Consortia, is continuing to support important research on laminitis and obesity, with its involvement in two new PhD programs in 2015.

British Equine Laminitis Research Expands: Why Are Some Horses More at Risk?

New research will look at blood flow to and within the horse's foot to determine why some horses and ponies are pre-disposed to laminitis. The research will be conducted at the Royal Veterinary College in Great Britain. This plastination casting of the blood supply shows the intricate variety of types of blood vessels that serve the foot. A dead horse's foot was injected with plastination material and the foot was treated to remove all evidence of tissue except the plastination. In this model, the blood vessels of the sole were removed to allow a full view inside the foot.  Corrosion casts like this one are sold by Hoofcare Publishing for educational and professional use.

Research announcement:

Great Britain's Royal Veterinary College (RVC) and the WALTHAM® research group are pleased to announce that veterinarian Elizabeth Finding, has joined them and the WALTHAM®-led International Laminitis Consortium to start her PhD on laminitis.

Elizabeth Finding

Finding will continue the essential search into why some horses and ponies have an increased risk of laminitis.

Laminitis is well-recognised as a major global welfare issue; it is a disease causing pain and suffering in those affected. Understanding why some individuals are prone to develop this painful--and potentially fatal--condition has been one of the major goals of the Laminitis Consortium so that targeted preventative measures can be put in place.

Anecdotal information has suggested that there is often an increase in incidence in laminitis following a bout of cold frosty weather. Previous work undertaken at the RVC has suggested that temperature may influence the reactivity of certain blood vessels of the hoof.

As part of her four-year PhD project. Finding will develop novel methods of assessing blood flow so that she can analyze changes associated with diet and season. In addition, she will be comparing innovative markers of blood vessel health between those that are and are not prone to laminitis.

Finding explains: “We hypothesise that ponies prone to laminitis have a dysfunction of the cells lining the blood vessels ("endothelial cells"). This may make them less effective in generating mediators which normally continuously dilate blood vessels and thus protect against the blood vessel constriction. It is thought that abnormal constriction may be initiated by the ingestion of too much rich grass especially under adverse environmental conditions."

The WALTHAM®–initiated International Laminitis Consortium comprises world-leading equine veterinary, nutrition and research experts interested in collaborating on the important topic of laminitis. It includes Dr Nicola Menzies-Gow and Professor Jonathan Elliott of the RVC, Professor Pat Harris of the WALTHAM® Equine Studies Group, and Clare Barfoot of Mars Horsecare UK Ltd.

(End of announcement)

•••••

From Hoofcare and Lameness: Elizabeth Finding is the lead author of a paper published in June 2012 in the American Journal of Veterinary Research (AJVR), "Evaluation of a technique for measurement of flow-mediated vasodilation in healthy ponies".

In that study, Finding and her colleagues tested between-pony and within-pony variations and interobserver and intraobserver agreements of an ultrasound technique for measurement of flow-mediated vasodilation (FMD) in healthy ponies. Testing and evaluation were favorable for using this technique in future research related to laminitis.

Finding is also the author of "Flow-Mediated Vasodilation in Healthy Ponies", published in the Journal of Veterinary Internal Medicine.

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© Fran Jurga and Hoofcare Publishing; Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. Please, no use without permission. You only need to ask. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page). To subscribe to Hoofcare and Lameness (the journal), please visit the main site, www.hoofcare.com, where many educational products and media related to equine lameness and hoof science can be found. Questions or problems with this blog? Send email to blog@hoofcare.com.  

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Disclosure of Material Connection: I have not received any direct compensation for writing this post. I have no material connection to the brands, products, or services that I have mentioned, other than Hoofcare Publishing. I am disclosing this in accordance with the Federal Trade Commission’s 16 CFR, Part 255: Guides Concerning the Use of Endorsements and Testimonials in Advertising.

Grazing Muzzles Reduce Pasture Consumption by 80 Percent in Grazing Ponies, According to New Study

"It's not funny!" this horse seems to be saying and there's no question that most horses are less than amused at the prospect of wearing muzzles. Would it be different if all the horses in the pasture had to wear them? This expressive photo is by the talented animal photographer Judith Whelan.

New research, presented at the Equine Science Society (ESS) Symposium in Nashville, Tennessee last month, shows that using a grazing muzzle can reduce the pasture intake of ponies by over 80 percent.

When horses and ponies, in particular, are given free access to grass, they appear to be more susceptible to obesity and related disorders, such as insulin resistance and laminitis, than are those with restricted access to grass.

However, simply reducing the amount of time a horse or pony is allowed to be out at pasture may not be as effective as previously thought. Another study, also presented at the ESS meeting, has shown that ponies may adapt their grazing behavior to eat more in a shorter time.

The new research shows that the use of a grazing muzzle could be a much more effective and reliable solution if used appropriately.

Grazing muzzles significantly reduce bite size and intake. Anecdotally, ponies fitted with grazing muzzles spend a greater proportion of time engaging in foraging- and eating-directed behaviors than their non-muzzled counterparts, yet they still either lose weight or retain an established, trim body condition.

The study, which was conducted by the British-based Waltham® Equine Studies Group in collaboration with Dr Annette Longland of Equine Livestock and Nutrition Services in Wales, aimed to quantify the effect of wearing a grazing muzzle on herbage intake by ponies.

Four mature ponies were recruited for the study. After an adaptation period, their pasture intakes were determined when wearing a grazing muzzle and when grazing without a muzzle. Pasture samples were obtained daily to assess the grazing available. Insensible weight loss (ISWL) was determined for each pony immediately preceding and immediately following each three-hour grazing period. Intakes were determined by changes in body weight (after taking into account the weight of any feces and urine produced plus the estimated ISWL) after the three hours of grazing, using a calibrated weighbridge.

Pasture intake by the ponies grazing for three hours without muzzles averaged 0.8 percent (with some eating close to 1 percent) of their bodyweight. This is the equivalent of up to two-thirds of the recommended daily dry matter intake for many ponies on restricted diets.

Even Kentucky Derby winners have to wear grazing muzzles. Here's Funny Cide, looking like he's saying, "Don't you know who I am? Don't take my picture when I'm wearing this thing!" in his paddock at the Kentucky Horse Park. (Sarah K. Andrew photo)

Owners therefore may under-estimate pasture intakes of un-muzzled ponies, even when they are provided with restricted time at pasture.

In contrast, the pasture intake of the ponies when wearing muzzles was around 0.14 percent of bodyweight over three hours, representing an average reduction of 83% percent compared to when they were not wearing muzzles.

Clare Barfoot RNutr, is research and development manager at Spillers®, a British feed company. Her comment on the research: “These figures clearly show how effective grazing muzzles appear to be as a method to restrict pasture intake. The study has given us helpful, practical guidance on how we can safely manage grass intake to control weight gain and reduce the risk of obesity-related disorders, without significantly compromising the natural behavior and wellbeing of our horses and ponies.”

Grazing muzzles must be used with care, should be properly fitted and horses and ponies should be adapted gradually to wearing them. Group and individual behavior should be monitored closely to observe any potential concerns caused by changes to the herd dynamics. Total exclusion muzzles are not advised.

Reference for this research: 
A Longland, ELNS, Pantafallen Fach, Tregaron, SY25 6NG, P Harris, WALTHAM Centre For Pet Nutrition, C Barfoot, Mars Horsecare UK Ltd, Old Wolverton, Buckinghamshire UK. (2011) The effect of wearing a grazing muzzle vs not wearing a grazing muzzle on pasture dry matter intake by ponies. J Equine Veterinary Science 31: 282-283

Additional reference for research mentioned in this article:
J. Ince, Institute of Biological, Environmental and Rural Sciences (IBERS). Aberystwyth University; A. Longland, ELNS, Pantafallen Fach, Tregaron, SY25 6NG C. J. Newbold, Institute of Biological, Environmental and Rural Sciences (IBERS). Aberystwyth University & P. Harris, WALTHAM Centre For Pet Nutrition.(2011) 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 Equine Veterinary Science 31: 283

Click here! Rev up your knee-to-hoof anatomy knowledge with the 3-D animation study tool everyone's talking about! Easy to order!

© Fran Jurga and Hoofcare Publishing; Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. Please, no use without permission. You only need to ask. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page). To subscribe to Hoofcare and Lameness (the journal), please visit the main site, www.hoofcare.com, where many educational products and media related to equine lameness and hoof science can be found. Questions or problems with this blog? Send email to blog@hoofcare.com.  

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Disclosure of Material Connection: I have not received any direct compensation for writing this post. I have no material connection to the brands, products, or services that I have mentioned, other than Hoofcare Publishing. I am disclosing this in accordance with the Federal Trade Commission’s 16 CFR, Part 255: Guides Concerning the Use of Endorsements and Testimonials in Advertising.

Laminitis Research: Equine Insulin Resistance Does Not Respond to Metformin Medication; Diet and Exercise Remain Key to Laminitis Prevention

Researchers in Australia tested the effects of a human medication, metformin, on ponies with insulin resistance, a condition that puts horses at risk for developing the endocrine or metabolic form of laminitis. The medication had no effect. (J.A. Holland image)

New research on the pharmacological management of the condition of insulin-resistance in horses and ponies has suggested that diet and exercise are still key in any management plan.

Insulin resistance (IR) is defined as the diminished ability of a given concentration of insulin to exert its normal effect on glucose dynamics in particular. This causes the body to keep releasing more and more insulin in order to elicit an effect. This may be one of the most predictable factors that determines whether a horse or pony could be more susceptible to what is commonly known as the "endocrine" or "metabolic" form of laminitis.

The University of Minnesota College of Veterinary Medicine's Equine Genetics and Genomics Laboratory explains insulin resistance this way:

Insulin  is a hormone involved in the regulation of glucose (sugar) levels in  the blood and tissues of the body.  In response to feeding, insulin is  secreted by the pancreas into the blood stream. Insulin in the blood  stream directs the glucose (sugar) absorbed from the food into the  body’s tissues including liver, fat and muscle.  Insulin resistance  occurs when insulin no longer has a normal effect on the tissues. In the  insulin resistant horse, the pancreas releases insulin into the blood  stream, and the insulin arrives at the tissues and binds the cells,  however the glucose enters the tissue cells at a much lower rate than  normal. This lower rate of glucose uptake into tissues results in higher  levels of blood glucose.

Horses and ponies compensate for  insulin resistance by secreting even more insulin into the bloodstream  in order to keep the blood glucose concentration within the normal  range.  Therefore, horses and ponies with EMS (Equine Metabolic Syndrome) have a higher  concentration of insulin within the blood, which can be measured to  determine if insulin resistance is present.

An important goal for owners and vets should be to prevent IR from developing, or to manage it before it contributes to the development/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. With no licensed drugs currently available for the treatment of IR in horses and ponies, off-label medications used for IR in humans are sometimes prescribed.

A trial was conducted by the School of Animal and Veterinary Sciences at Charles Sturt University in New South Wales, Australia and the Department of Clinical Studies at the University of Pennsylvania's New Bolton Center, in collaboration with the Waltham Equine Studies Group in Great Britain.

The study's intention was to confirm the positive effect of the human medication metformin on insulin and glucose dynamics in insulin-resistant ponies so that this treatment could be used as a positive control in other studies.

Glenys Noble BAppSc(Equine Studies) PhD, along with PhD candidate Kellie Tinworth BSc(hons) MSc, carried out the clinical trial in Australia. Six insulin resistant, non-obese ponies were repeatedly monitored by means of a frequently-sampled intravenous glucose tolerance test (FSIGT). Metformin ia a drug reported to enhance insulin sensitivity of peripheral tissues in humans without stimulating insulin secretion. It was administered twice-daily (15mg/kg BW BID) to three of the ponies for 21 days.

Meanwhile, the three remaining ponies formed a control group, and each received a placebo. After a wash-out period, the treatments were crossed over.  A Frequently Sampled Intravenous Glucose Tolerance Test (FSIGT) was conducted to evaluate the level of insulin resistance before and after each treatment.  The ponies' body weight, body condition score and cresty neck score were also assessed. They did not change during this study.

Ray Boston MSc PhD is Professor of Applied Biomathematics in Clinical Studies at the University of Pennsylvania's New Bolton Center. He analyzed the data using MinMod, a computer program to calculate glucose effectiveness and insulin sensitivity from the frequently sampled intravenous glucose tolerance test, and Stata 10.1 statistics analysis software. No change in insulin sensitivity or glucose dynamics was seen under the control conditions or in response to the dose of metformin given in this study to these ponies.  

What does this study mean to horse owners? Clare Barfoot RNutr is the research and development manager at the British feed company Spillers®; she reviewed the research and said: “Although clinical trials with metformin are ongoing, this trial was consistent with our previous work showing that the bioavailability of metformin in horses is poor, and chronic dosing at these levels may not achieve therapeutic blood concentrations.”

She continued: “On this basis it would seem that a fiber-based diet that is low in starch (found in cereals) as well as  (being low in) sugar and fructans (found in grass), in conjunction with regular exercise if possible, is still the safest and most effective way to manage insulin-resistant ponies. It is important to recognize that, even if other doses of metformin are shown to be beneficial in the future for certain sub-groups of animals, full consideration to diet and management should remain a key tactic.”

The Waltham® Equine Studies Group, headed up by Dr Pat Harris MA PhD, VetMB DipECVCN MRCVS, provides the scientific support for the Spillers® and Winergy® brands sold in Great Britain.

To learn more: K. D. Tinworth, R. C. Boston, P. A. Harris, M. N. Sillence, S. L. Raidal, G. K. Noble (In press). The effect of oral metformin on insulin sensitivity in insulin-resistant ponies The Veterinary Journal; Available online 23 February 2011, doi:10.1016/j.tvjl.2011.01.015.

Thanks to Spillers for sharing this information with Hoofcare and Lameness.

© Fran Jurga and Hoofcare Publishing;  Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. Please, no use without permission.  You only need to ask. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page).  To subscribe to Hoofcare and Lameness (the journal), please visit the main site, www.hoofcare.com, where many educational products and media related to equine lameness and hoof science can be found.  Questions or problems with this blog? Send email to blog@hoofcare.com. 

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Disclosure of Material Connection: I have not received any direct compensation for writing this post. I have no material connection to the brands, products, or services that I have mentioned, other than Hoofcare Publishing. I am disclosing this in accordance with the Federal Trade Commission’s 16 CFR, Part 255: Guides Concerning the Use of Endorsements and Testimonials in Advertising.

Laminitis Prevention: Is Current Body Condition Scoring Irrelevant for Ponies?

by Fran Jurga | 18 September 2009 | Fran Jurga's Hoof Blog

A 9.2 hand, 12-year-old spotted pony named Firefly suffered from overgrown feet and laminitis in England in April 2007. She couldn't walk properly, but her owner refused to have her cared for, nor would she sign the pony over to the World Horse Welfare. A court case ensued and the owner lost her right to own horses for two years.

Here's Firefly in September 2007, on her way to full recovery and adoption to a new home. The research project funded by WHW at the University of Liverpool suggests that it is difficult to assign an objective body condition score to ponies using the system designed for larger horses.

Researchers at the department of clinical science at Britain's University of Liverpool, with support from the World Horse Welfare charity, presented new research at the annual convention of the British Equine Veterinary Association(BEVA) last week.

The question: how accurate is conventional equine body condition scoring for weight loss management when the equine being evaluated is an overweight pony?

The study, entitled Managed Weight Loss in Obese Ponies: Evaluating Weight Change, Health and Welfare, involved five mature, overweight or obese ponies and aimed to restrict their feed intake (on a dry matter basis) to 1% of body weight of a chaff-based complete diet for 12 weeks.

During this time the ponies' weight change, health parameters and behavior were monitored. All ponies remained healthy throughout the whole trial and an appropriate and safe rate of weight loss was achieved.

Clare Barfoot BSc (Hons) RNutr, registered nutritionist and the research and development manager for SPILLERS® (British horse feed company) explained: “Body weight decreased at a steady rate. However, despite significant weight loss, the body condition scores of the ponies didn't change. This highlights the concern that body condition scoring may not be the most effective way to monitor early weight loss in ponies.”

Even in this well-managed study, the feeding activity of the dieting ponies was decreased by 74 percent compared to ad libitum intake, highlighting the need for a practical feeding system that is both effective at managing weight loss but is sensitive to behavioral needs.

The WALTHAM® Equine Studies group was closely involved with this study as it has been with other groundbreaking work on equine obesity, such as showing that an obese body condition score was associated with increased insulin resistance back in 2003, and developing the cresty neck scoring system.

In response to the study, the research group is in the process of developing a new condition scoring system designed specifically for ponies. “This will involve validating the relationship between actual measurements of body fatness and the external appearance of the pony,” said Alex Dugdale, lead researcher for the study at Liverpool University.

Note: information provided by Spillers was used in the preparation of this blog post.


© Fran Jurga and Hoofcare Publishing. No use without permission. You only need to ask. Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page). To subscribe to Hoofcare and Lameness (the journal), please visit the main site, www.hoofcare.com, where many educational products and media related to equine lameness and hoof science can be found. Questions or problems with this blog? Send email to blog@hoofcare.com.