As the weather warms up in Dorset and Hampshire it’s important to continue thinking about your horse’s weight. We have spent the last few months discussing the issues faced by the overweight horse as well as ways you can help them as owners.
Laminitis has always been considered a disease in its own right, however recent research has changed the way we look at it. It is now viewed as a symptom of another underlying problem such as Equine Metabolic Syndrome (EMS) or Pituitary Pars Intermedia Dysfunction (PPID). It’s an incredibly painful condition that can lead to horses being euthanised due to the effects. Prevention is by far better than management as there is no cure, so we’ve laid out an explanation of the condition and we will be following up with tips and advice to help owners throughout the year.
Both EMS and PPID are associated with irregular insulin levels, higher levels of insulin in the blood have been shown to cause rapid onset laminitis, insulin controls the glucose levels in the blood. The release of insulin signals to cells around the body to absorb the glucose from the blood. However, many horses have abnormally high levels of insulin as a response to eating too much high starch and/or sugary meals suggesting this increase in insulin levels may lead to laminitis.
The hoof wall has two layers; an insensitive outer layer (horn) and a sensitive inner layer know as the laminae. Laminitis affects the blood flow to these laminae, causing inflammation and swelling within the hoof. This increase of pressure within the foot causes crippling pain. As the condition continues, the laminae become starved of oxygen and blood, ultimately damaging them. The laminae support the pedal bone in the horse’s foot, which obviously takes the whole weight of the animal. If left unchecked, laminitis can cause the pedal bone to rotate as the laminae fail and become unable to support it.
Laminitis can be acute or chronic.
Acute laminitis tends to come on quickly and painfully. The horse or pony will display a reluctance to walk or move, some may even lie down to take the pressure off their feet and refuse to get back up. There will be visible lameness, particularly when walking on hard ground, some may avoid hard or stony ground altogether. Often they will place their feet heel first and when stood still you may notice them leaning backwards as the pain tends to be worse in the toes. When you examine your horse you will probably find a digital pulse quite easily.
Chronic laminitis tends to be more ongoing. It is generally the result of relapsing from previous attacks. Growth rings around the hoof wall are generally a good sign that the horse has suffered from laminitis in the past, be careful not to confuse them with hoof rings, and if you have any doubt ask your farrier or give one of the vets a call to discuss.
The two most common causes of laminitis are hormonal diseases: Cushing’s disease also known as Pituitary Pars Intermedia Dysfunction (PPID) and Equine Metabolic Syndrome (EMS).
Cushing’s disease (PPID) is associated with the disruption of control of the hormones the pituitary gland produces. This condition is most common in older horses, however it cannot be ruled out in younger animals. PPID is caused by the degeneration of neurons in the hypothalamus; this degeneration takes place over time, which is why the condition is more often seen in horses over the age of 15. These neurons were releasing dopamine which controls the production and release of the hormones from the pituitary gland. One of the consequences is an increased production in ACTH which results in increased cortisol production (stress hormone) and results in increased blood insulin which predisposes to laminitis.
For more information on Cushings, and a more in depth explanation of what happens with the horse’s brain, head to Care About Cushings
Symptoms of Cushings (PPID) include:
- Changes to the horse’s coat to include:
- Longer, thicker or curlier hair
- Later than normal shedding
- Excessive thirst and drinking
- Excessive urination
- Loss of muscle tone
Equine Metabolic Syndrome (EMS) is a form of insulin dysregulation similar to Type II Diabetes in humans. It is most common in horses that are obese the mechanisms of insulin dysregulation are very complicated. Some types of fat produce produces adipokine hormones and cytokines both of which reduce the body’s sensitivity to insulin. It can also result in a constant, low level inflammation.
Symptoms of EMS include:
- Fat pads
- Repeated Laminitic Episodes
- Insulin Dysregulation
If you are at all concerned that your hose of pony is displaying signs of laminitis, EMS or PPID a vet should be consulted as soon as possible.