There are three reasons for a horse to be underweight:
- the food isn’t available,
- the food is available but can’t be swallowed and
- the food is available, swallowed but isn’t absorbed.
Let’s look at each.
1) The horse above was neglected and is the obvious result of having no food to eat. But there can also be a more sinister story, as I have experienced once.
2) I was floating two horses on a farm where I discussed their horses’ nutrition. They were both a BCS of 4. The owners insisted they were purchasing the feed, but when they investigated, they soon realized the farm was feeding their food to the barn’s horses, not these two. The result was still starvation.
3) The mare above was 38 years at the time of this picture. Her gut no longer absorbed what she ate. However, she still chewed and swallowed grass and all other food in the form of water-soaked forage plus grains.
In between these two reasons for weight loss with food availability are the dental conditions preventing the food in front of the horse from getting into the digestive tract. They remain hungry, but for reasons of obstruction, the food never gets into them. Besides bad teeth, there are other reasons: foreign objects in the mouth (see the topic of oral foreign objects), esophagus dysfunction (partial paralysis, choking, diverticulum) and neurologic dysfunction affecting the swallowing mechanism.
Unfortunately, this inability to swallow happened to a client’s husband, who could no longer eat after a stroke. He passed away after refusing to be kept alive with a feeding tube.
Understanding the causes of starvation may help to correct this situation, but unfortunately, most starved horses die. I have rescued and evacuated from farms many starved horses in my career, but most, after passing a certain point, do not recover. One of the post-mortem findings I have correlated is serous atrophy of fat, where the fat within the bone marrow is completely gone.