The L Word, Part I

Not "lame". I'm talking about the one with the big "L".

Laminitis

Ring around the rosie.
Or rather, rosy ring around the coronet band.
All 3 of Lily's white hooves have this band at the moment. :(

Since this is not an easy post to write, I'm going to turn it into an educational thing. So this doesn't happen to anyone else.

First things first: there is no such thing as Equine Metabolic Syndrome. Before the ongoing research, vets used to lump Cushing's disease and insulin resistance under this general term, and some vets still do, which creates a lot of confusion for horse owners. They are two very different diseases with symptoms that can seem similar until you start looking into the causes. You can have a horse with both Cushing's AND IR (which is a BITCH to manage, btw. I'll tell you why in a minute), but just because a horse has IR doesn't mean it automatically has Cushing's and viceversa. I have a personal fascination with these two diseases in horses as there is nothing quite like them in any other species. Cushings is common in dogs and people but it does not present at all the way it does in horses.

1. Cushing's disease - aka Pituitary Pars Intermedia Dysfunction (PPID) is caused by a tumor in the pituitary gland. The pituitary gland is located in the center of the brain and is in charge of controlling the endocrine system. When an adenoma or benign tumor pops up in the pituitary, it causes an overproduction of a peptide called pro-opiolipomelanocortin (POLMC, for short), which throws the horse's entire endocrine system out of whack. One of the problems it causes is abnormally high cortisol levels. Symptoms of Cushings: excessive drinking and urination, loss of muscle along the topline, potbellied appearance, sore feet and even founder in late summer-fall, excessive sweating or anhidrosis, increased susceptibility to infections and allergies, and a long, sometimes curly, coat that either sheds out late or doesn't shed at all.

Long curly coat and muscle wasting along the back, creating a swaybacked appearance.
This is classic Cushings but I can tell you right now: a LOT of horses DON'T initially present like this. This is actually ADVANCED Cushings. There were 5 Cushings horses at my previous barn and there are 2 at my current barn: none of them ever did develop the long curly coat prior to diagnosis. If you have an older horse with sore feet in late summer/fall with no other signs, get him tested for Cushings STAT.

If this horse was mine, I'd have him tested for Cushings.
Dear sweet Paris, whose portrait I made recently, looked just like this horse when he was first diagnosed with the disease last year. He didn't have sore feet or even that much muscle wasting along his back. He just had this long soft shaggy coat that wouldn't shed. 

It is quite common in older horses but has been known to present in horses as young as 8 years old. If diagnosed early it can be managed fairly easily with a medication called pergolide. The dose may need to be adjusted throughout the horse's life, and may need to be temporarily increased in the late summer/fall. Why? Because in the late summer/fall, horses' cortisol levels naturally rise to stimulate the body to grow that long winter coat that will keep them warm. In a Cushing's horse, whose cortisol levels are already high to begin with, that seasonal rise can be lethal: it is what can cause laminitis and even founder in an afflicted horse during this time of year. This is often the very first sign of Cushing's. Some Cushing's horses can also develop laminitis/founder in the spring when their hormone levels change again with the warmer seasons. Unless that Cushing's horse also has IR. To read more about the physiology of Cushing's in horses, go here.

FYI: Lily is barely 7 years old and has never had sore feet in the fall. She does NOT have Cushing's.

2. Insulin resistance - I think this is one of the most misunderstood equine diseases. I briefly entertained the idea of becoming an equine vet so I could specialize in internal medicine and then just focus on this one disease and researching more about it. I'm going to tell you guys a lot more about IR than about Cushings because it's what we may end up dealing with here.

You can see insulin resistance in horses of any age. Some breeds can have a predisposition to it, especially breeds known to be "easy keepers", like Arabians, Morgans, Paso Finos and several of the gaited breeds, some Quarter Horses (especially halter bred ones), Mustangs and most pony breeds. Most of these breeds originated in barren areas of the world where survivors were the individuals who could subsist on less food. Place an individual of any of these breeds in a lush green pasture and you will quickly end up with something like this:

Classic IR horse.
One blade of grass from a full metabolic blow-up...

What is insulin resistance? In theory, it's not really a disease. It is simply a part of some horse's metabolism. These horses are intolerant of high amounts of starch and sugar. It's like having a peanut allergy in people: they just shouldn't eat them.

What happens if an insulin resistant horse eats sugar/starch? (Like lush green grass, rich hay, sweet feed) Well, this:

Cresty neck on a horse at a healthy weight. Despite being at a healthy weight, this horse could still develop laminitis if exposed to sugar/starch. The crest can often be completely eliminated if the horse's owner is able to maintain them on a low sugar/starch diet.

Lumpy, cresty neck typical of an overweight IR horse.

Lumpy fat deposits over body, also typical of an IR horse, though I have yet to see them as demarcated as this individual's in real life. But these are the areas where IR horses tend to develop fat pads.

Stance of a severely laminitic/foundered horse

Pink line growing down on a horse's hoof. (Not Lily) This can be caused by trauma to the hoof but can also be considered an event line in a pink hoof.

Solar bruising. (Not Lily) Can be from trauma, but can also be a sign of early laminitis.

Laminitis to founder.
I can post photos of what founder looks like in a hoof, but the photos are pretty graphic. Not for the faint of heart.

Why does that happen?

The following paragraph is from Equine Cushing's and Insulin Resistance: The Physiology of IR:

"With insulin resistance, circulating levels of insulin in the blood are elevated but blood glucose stays normal. The cells are resistant to insulin's signal to take up glucose, but higher levels of insulin get the job done. Horses do not progress on to be frankly diabetic as easily as other species do. Diabetes mellitus is when blood sugar is higher than normal.

High levels of insulin tend to shut down the burning of fuels in muscle and fat, channeling them instead into storage forms. Glycogen goes down because glucose entry is impaired, but at the same time the burning of fuels is inhibited so more fat gets stored - a vicious cycle."

It is those very elevated levels of insulin in the blood that will cause laminitis in an insulin resistant horse. 

To complicate matters more, you can't starve an overweight IR horse because it can actually worsen the IR. You feed forage in smaller amounts, from 1.5% to 2% of the horse's body weight, ideally in haynets so it takes the horse longer to eat. No grass; the horse must be in a dry lot. And once the laminitis, if present, is resolved, that IR horse must be exercised. Exercise and a low sugar/starch diet are the only ways to control insulin resistance. 

Signs that your horse might be IR include a cresty neck and/or abnormal fat deposits over the body even with weight loss; history of laminitis induced by grass; puffiness in hollows above eyes; and in advanced stages you may see weight loss, loss of muscle and increased thirst and urination (which is one of the symptoms that can be confused with Cushing's).

A horse with BOTH IR and Cushing's will need to have a low sugar/starch diet, be managed with pergolide, and will have to live in a dry lot, with close monitoring of the horse's feet in both fall and spring.

3. Other causes of laminitis:
- "Road founder" - caused by running a horse too fast or long over a hard surface.
- Grain overload - such as when a horse breaks into the feed room and gorges itself on all of the grain.
- Black walnut shavings - can be common in shavings obtained from wood furniture stores. It doesn't take a lot of black walnut in the bedding to cause laminitis.
- Support limb laminitis - when, for example, a horse seriously injures one leg (like a fracture) and they need to transfer their weight to the other supporting limb for extended periods of time.
- Endotoxemia/infection - when a horse has an increased circulation of toxins in the blood, such as with certain poisonings, infections causing elevated fevers for prolonged periods of time, bacterial diarrhea, Lyme disease, etc.
- Overzealous trimming/shoeing - I've heard nightmare stories of trimmers that knocked off so much hoof at once that they caused horses to founder. Hence why I trim myself. Bad shoeing can also cause laminitis.

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So why is this metabolic problem of so much interest to me?

Because I had an IR horse. Cloud was IR.

Cloud a few weeks before I adopted him. He'd already been in work over 2 months and had lost quite a bit of his excessive weight. You can kind of see the fat pad that he still had over his shoulders, and he had a significant one over his tail head. He was still on the rescue's oats and T&A diet.

When I first decided to adopt him, I didn't do a formal pre-purchase on him. I'd known him and worked with him for 3 months so I knew him personality-wise and knew he was sound. He was originally obese, however, with odd fat pads over his body, due to a diet of oats and T&A hay at the rescue, and he continued to retain some of those fat pads despite slowly increasing work with me. Prior to adopting him, we did flexion tests to locate any possible arthritis (he had none yet at age 15, a testimony to his nice leg conformation) and I had bloodwork done on him: a CBC and chemistry panel, and I talked to my vet about testing him for Cushing's. He urinated a LOT and did sweat excessively but my vet recommended also testing him for insulin resistance. At the time I didn't know that the two conditions were separate issues; I just thought Cloud might be pre-Cushing's, a term that is often used to refer to IR by people who don't know what it is.

Cloud came back negative for Cushing's but positive for insulin resistance. I signed his adoption papers anyway and immediately became a member of Dr. Kellon's Equine Cushing's and Insulin Resistance Group to start educating myself, as I knew I had in my hands a condition that, left unmanaged, might result in founder in my horse. I learned that I needed to keep him on a very low starch diet and make sure that he stayed at a healthy weight with regular exercise. I switched him over to Triple Crown Lite, a very low starch ration balancer, of which he only received a cup twice a day (you can feed it in that small of an amount), and discovered that one of our local feed stores actually sold low sugar low starch timothy hay that had already been tested. I started him on that hay right away as well, offered in small hole hay nets so that it would take him longer to eat them, simulating all-day grazing. The feed store in South FL that sells tested hay is Finish Line Feed in Dania Beach, FL. They don't announce this hay on their website, but you can walk into the store and ask for it. When Cloud was in heavier work, I started adding beet pulp to his meals. The same feed store sold unmolassed beet pulp which made my life so much easier. If they ran out (this happened often), I'd buy molasses beet pulp, soak it in a bucket, dump it into a large colander, and rinse the beet pulp with the hose until the water coming off of it ran clear: this is how you remove the molasses. IR horses at a healthy weight in full work can have as much plain beet pulp as they want to eat - it is pretty much the one safe food for them. In a laminitic IR horse, you can actually eliminate all forage and just feed straight unmolassed beet pulp until you have the laminitis under control. It's called the "IR emergency diet".

Cloud

Cloud never had sore feet and he never developed pulses in his legs. One perk of South FL is that sand is the most prevalent footing: it doesn't take long to turn a paddock into a drylot when you have a lot of horses being turned out in them. So I never had a problem with having to worry about Cloud's exposure to grass. I was lucky with Cloud - some IR horses are so sensitive to starch that even the wrong supplement can send them into a downward laminitic spiral.

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After Cloud, I've had hard keepers. But after so much research done into equine nutrition, I still refuse to feed a high starch diet. I have this visceral reaction to the thought of feeding a high starch grain to my own horses. If others want to feed their horses that way, it's their call. But I just don't feed my own like that. Diets high in cereal grains like oats and corn with added sugars like molasses can cause hyperactivity, colitis, colic, gastric ulcers, foot problems like thrush, and if your horse happens to be IR at all, you may find yourself with a laminitic horse in your hands.

Lily was eating sweet feed and T&A during the 2 months that she belonged to my BM. When she became mine, I switched her over to free choice straight timothy hay (offered in hay nets) and 5 lbs a day of Triple Crown Low Starch pellets. When I discovered she was more of a hard keeper, she started getting beet pulp with her grain three times a day and added rice bran oil. I also gave her a flake of alfalfa hay after hard workouts as a sort of "protein shake." She did fantastic on this diet. I do miss being 100% responsible for everything that goes into my horse and the co-op arrangement we had at my self care barn.

That barn, however, had no grass at all. All the turnouts were sand. When I moved Lily to MD in October of 2012, there was still grass on the ground up here. My BM at the time introduced her slowly to it, slowly increasing the amount of time she got to spend on green pasture until she was out for 12 hours a day on it (there was no field board offered at that barn). In April of 2013, Lily injured her left hind in turnout, straining her annular ligament. She was immediately put on strict stall rest. In July 2013 when Lily finished her rehab from the injury, we re-introduced her to grass again in the same fashion until she was out 24/7.

We never had a problem.

Until now.

To be continued in a second post. It's going to be too long otherwise.