By Julia Shrubb MA VetMB CertAVP(EM) MRCVS, Ashbrook Equine Hospital.
Laminitis is a very common condition that is always painful, potentially life-threatening and causes suffering even in mild cases. This preventable condition is often costly, difficult to manage and can result in long term damage.
Traditionally, laminitis has been associated with grass and overweight ponies; however, our understanding of the underlying factors has significantly improved in the last decade. It is now known that about 90% of “grass-associated laminitis” is due to underlying hormonal disorders causing insulin dysregulation; either PPID (Pituitary Pars Intermedia Dysfunction aka “Cushings”) or EMS (Equine Metabolic Syndrome).
1. Recognising if your horse is at risk or showing signs of EMS or PPID is the first step in preventing laminitis. EMS and PPID are separate conditions but share many features and can occur together in the same horse (see table 1).
PPID is a degenerative disorder of old age, like Parkinson’s disease in humans. It affects around 20% horses over 15 years and increases in prevalence with increasing age. There is currently no known way of preventing PPID but recognising early signs (see table 1) and getting a prompt diagnosis with a simple blood test, allows pergolide (Prascend) treatment to be started. If the PPID is well controlled the laminitis risk massively reduces. This makes daily pergolide treatment more cost-effective than treating laminitis and also prevents unnecessary pain and suffering.
EMS is a syndrome commonly seen in native breeds and “good doers”, associated with obesity, laminitis and insulin resistance. Obesity and inactivity increases insulin resistance, thereby increasing the risk of EMS, much like type-2 diabetes in people. Many “good doers” have been bred to survive on poor grazing or work hard for transport, war or farming, so are genetically predisposed to EMS.
If you suspect your horse has EMS, your vet can test blood insulin levels before and after feeding to identify horses with abnormally high insulin concentrations. However, it is wise to treat all “good doers” as if they have EMS.
2. Ask yourself honestly if your horse is overweight
Almost 50% of pleasure horses are obese. Unfortunately, it is so common to see overweight ponies that we can lose sight of good body condition. Horses with EMS may have generalised obesity (fat all-over) or regional obesity, with a cresty neck, fat pads and a fat sheath/udder. Often ponies with EMS have little fat over their ribs but fat pads elsewhere; however, not all outwardly obese animals are insulin resistant and neither are all insulin resistant animals obese.
3. Monitor your horses weight monthly either using a weigh bridge or weigh tapes (girth and neck measurements). Weigh tapes are not accurate but show trends which can be hard to identify when you are seeing your horse daily.
3. Assess the diet to promote weight loss (if needed) as well as reducing sugar content. Most horses that are at risk of laminitis and are in light work need a diet based mainly on forage, together with a balancer. Feeds with the “Laminitis Trust” approval mark may be used in small quantities.
Even hay can have a significant amount of soluble sugars which can be reduced by soaking for several hours. Hay analysis can be useful as it is very variable and ideally hay should have less than 8% soluble carbohydrate. Weighing all feeds is very helpful. Your vet can give tailored advice for your horse, but a good starting point for weight loss is to feed 1.25% of your horse’s ideal bodyweight each day.
4. Restrict grass. Occasionally it is advisable to completely restrict grazing, such as during clinical laminitis or if your horse has uncontrolled PPID or EMS. However, there are many benefits to being at pasture and careful planning can reduce the risk. Greedy ponies on lush pasture can eat their daily requirement in 3 hours, so simply limiting grazing time is not useful. Fencing off a small area to create a bare paddock or turnout e.g. arenas, woodchip covered areas can be a useful alternative. Grazing muzzles work for some animals but should not be used all day. They need to be correctly fitted so the pony can drink and the grass length sufficient to allow some grazing.
Cold spells are known to cause an increase in laminitis cases. This was thought to be due to increased fructans in stressed grass but has been disproved. It may be due to hard ground and increased food intake but do take care during frosty weather.
If the PPID is well-controlled with pergolide and the pony is not overweight, restricting grass is less concerning.
5. Increasing exercise helps reduce insulin resistance and uses calories to aid weight loss. For maximum benefit, 30 minutes of trot and canter exercise at least every other day is suggested.
6. Use winter wisely. Horses naturally lose weight in the winter and gain some in spring and summer. This keeps their metabolism healthy. Does your horse really need that extra rug? Horses are comfortable at much lower temperatures than humans and use more energy keeping warm.
7. Talk to your farrier to see if there are signs of laminitis despite no obvious lameness problem; such as rings on the hoof wall that are wider at the heel than the toe or a stretched or bloody white line.
8. Do not ignore mild signs of laminitis. A horse that is “a bit footy” or is always tender after trimming is likely to have mild laminitis and needs veterinary attention before it worsens.
9. Ask your vet for advice! Vets would rather help prevent laminitis than see a horse suffering with the debilitating and painful effects of laminitis.