Sunday, October 19, 2008

Grass founder

Naigen, Spring 2007. She was still ribby, but enjoying eating the dandelions in the back riding ring.

Because the frost has set in it is an extremely dangerous time for horses prone to founder.

I hope this can benefit someone. I got 100% on it. My instructor was very impressed and it is something that has stuck with me ever since.
Grass founder

Fact sheet by Sydney Kotow

Twelve little ponies graze contentedly in a hilly green pasture during a perfect spring day. It may seem like the dream image to a little girl or horse lover but where the green grass grows, disaster can strike.

Founder, right next to euthanasia is a word horse owners hope will never be associated with their equine health record. We go to every precautionary measure from muzzles to grass less paddocks but do we really know the villain behind this menacing disease?

Founder, the aftermath of laminitis. It can start innocently enough; a horse eats the wrong grain, reacts to medicine, is worked on hard ground or in our case, eats grass.

Laminitis and founder are often used interchangeably but they are two very different diseases closely related to one another.

Laminitis occurs when blood flow is interrupted (short term, constant or infrequent) to the sensitive and insensitive laminae (the tissues that connect the coffin bone to the hoof wall) of the horse’s hoof, causing them to separate. When the horse develops laminitis the laminae experiences decreased blood flow, nutrient supply, oxygen, edema, and death of the tissues in the laminae. Causes for the edema in the laminae are blood clotting, swelling around the blood vessels, and restriction of the veins, that in turn cause the blood to be deterred away from the capillaries in the laminae. (Beadle, 1999) There are two main types of laminitis, acute and chronic.

Founder and laminitis are often confused, founder cannot happen without the horse developing laminitis first and the laminar tissues weakening. When the horse founders the coffin bone tears away from the lamina and rotates. From there the bone can tilt downward until it penetrates the sole of the horses hoof. Generally, severity of rotation in the coffin bone is measured in degrees. 10 being moderate and 40 being severe. Beyond 40 degrees the bottom of the coffin bone will become vertical and penetrate the hoof sole. Over time a vertical coffin bone can deteriorate and the toe portion of the bone can become flat. When the coffin bone begins to rotate, pressure is placed on the toe of the hoof creating the “elf shoe” deformed look in the hoof if veterinarian and farrier care is not called upon. When the coffin bone detaches itself from the laminae it never completely regains it’s former attachment and allows the horse to become prone to founder again. (Avisar, 1996)

Founder almost always occurs in the front feet and it’s easy to see why. A horse’s body was built front heavy with a long thick neck and big head. At adulthood the horse typically carries 60% of his body weight on his front limbs, putting pressure on sore feet with founder.

Founder can be thrown upon a horse in many ways. As caretakers we should know what the signs are and when to call the vet. Any case of laminitis or founder is an extreme emergency. Without a hoof you have no horse so take preventative measures and call the vet early. The horse will usually come in from the pasture or out of the stall lame. Digital pulses on each foot will feel as if they are pounding, heat can be felt, and the horse will be extremely sensitive to hoof testers in the toe area. The horse might shift his weight from one leg to another and walk with very stiff limbs. In extreme cases the horse will not stand square and will attempt to put more pressure on the hind legs by leaning in an attempt to find relief. Some horses lie down on their sides as this is the only way they can relieve the constant pressure being placed upon their sore feet. A horse that has developed chronic laminitis will have rings parallel to the coronary band and bleeding or an enlarged white line area on the sole of the hoof. If the case has been left long enough the coffin bone may drop and penetrate the sole. In cases of neglect, death can be quick to follow.

Grass founder is a very puzzling disease, there are still holes in research today. It is essentially the same as grain founder but with different ingredients. Easy keepers are thought to be more at risk for grass founder as well as overweight, under worked horses. Do not exclude very fit well fed athletes, any horse is at risk. Numbers of grass founder cases increase in the spring and fall; right when growing starts and stops with temperatures fluctuating.

There was a time when grass founder was thought to be caused by very rich green grass. Now we learn fall grass can give horses even more of a risk as it starts to brown and attempts to store nutrients to keep itself alive before the winter frost sets in. Research has shown a starch like carbohydrate to be the delinquent. This carbohydrate is known as fructan.

Fructan is stored by grasses and hays for times of need like an overcast or sunny day with cool temperatures. The carbohydrate is used by plants when photosynthesis of their cells slow or cease. Cloudy days or temperature drops make growing conditions for grasses less ideal so they store fructan for these times. When the sun comes out from behind the clouds or day breaks fructan production commences. Since the weather in spring and fall can change from warm to cool rapidly within days or hours the levels of this carbohydrate are highest to help the plant survive. (Christie, 2007)

Cutting hay during times of environmental stress such as an overcast day or when photosynthesis is not optimal will leave your hay with very high levels of fructan. When the hay is cured the levels stay consistent.

It is almost impossible to test your grazed grasses for levels of fructan because these levels go up and down during the day and vary day by day depending on the weather and where the sun is in the sky.

Fructan is digested in the hindgut, fermenting rapidly and causing an excessive amount of lactic acid buildup. The lactic acid kills the bacteria in the hindgut, which releases endotoxins into the blood. Endotoxins are essentially the dead bacteria. When fructan ferments the bacteria multiply so rapidly that they die off quickly because of the increased acid content in the hindgut. (Thomas, 2003)

Endotoxins effect the cardiovascular system, which in return shuts off the run of oxygen and restriction to the feet. This results in laminitis, the weakening of the hoof structure, and ultimately the rotation of the coffin bone or founder.

There really is no proven way that will help all horses recover from grass founder. However, first removing the foundered horse from grass and any grain or concentrates altogether, is a good method until he is sound. Cool season grasses such as timothy, fescue, and clovers are at a higher risk of larger fructan levels. Although fructan levels are lower in warm season grasses it does not mean the horse cannot founder off them or that they have no fructan in them. Keeping previously foundered horses off grass during spring and fall when temperatures fluctuate is a must as well as never turning a horse out that foundered in the same paddock that gave him the condition in the first place; he will likely founder again. If that paddock is the only one accessible to you, grazing muzzles are an inexpensive way of preventing grass founder.

Some farriers can apply corrective shoeing and others are experienced in the areas of the natural trim, which has recently been shown to work in some cases even better than shoes.

Take the horse or pony off all grain and call the vet immediately if you suspect any signs of laminitis or founder. X-rays of the foot can be taken to determine if the coffin bone has rotated and what treatment should be applied. Some pain medications can be applied to temporarily relieve pain but they only cover up symptoms, not treat them.

It is recommended to feed hay with 10% of fructan or less. This is one more reason it is very important to get a hay analysis. Alfalfa is a good alternative by itself or mixed with grassy hay to make up the protein and calories the grain once supplied to the horse.

Some supplements on the market today help the horse keep the weight on without the risk of too much carbohydrates, starches, or sugars added to the diet. They could be added if the horse has a hard time keeping on weight without a concentrate or grain. Too many calories can be counterproductive in the healing process. Once the horse has healed it is recommended to put him on a low starch, high fat diet to help prevent a repeat episode.

Founder Facts

  • For prevention avoid letting horses graze in the late afternoon/evening, when temperatures drop below 40 or the morning to follow a temperature drop. Overcast days also pose a threat.
  • Brown grass in the fall poses a very high risk, as fructan has saved up high levels in an attempt to live out as long as it can until the winter frost. Wait until grass has browned all the way down to the roots before allowing horses to be turned out on it.
  • Putting grazing muzzles on horses that are high risk or have foundered before are very good and safe precautionary measures. Also turning out in a paddock without any grass is a good preventative choice.
  • When hay is cured fructan levels stay the same. It is possible your horse may have foundered off the hay instead of grass. Local feed stores usually can send samples of your hay to test for levels of fructan.
  • Every case of founder is different. Every case will require a different treatment. Some work, others don’t. Ask your vet and equine nutritionist what nutrient requirements your foundered horse will need and any special things you should be adding to his diet.
  • Research, research, research! If your horse founders, chances are you are in for a long and heartbreaking battle. Do as much research on methods of treating founder as you can. Talk to other people who have had foundered horses, contact specialist farriers and veterinarians. The more you know, the more you will be able to help your horse. Any little bit can help but when it comes to your horse’s feet, take all precautions.
  • Gradually introducing your horse to grass can make the risk of grass founder smaller. Start with 10 minutes and add 5 minutes each day until the horse can be let out to graze for the desired amount of time. Remember, once horses are let free in a grass filled paddock it can be hard to coax him to come back inside. Hand grazing initially is a good insurance plan.


Ralph E. Beadle, DVM, PhD 1999
Professor of Veterinary Medicine

(to find the year the article was written right click and view page info)

Yehuda Avisar, DVM 1996

published in ANVIL Magazine, October 1996

Sarah Christie 2007

Horse illustrated magazine march 2007

“confounding grass founder”

Heather Smith Thomas 2003

Grass founder part 1 and 2

This is something cute I found in my research. I did not know if it was appropriate to place it in my assignment because I did not write it but it is very cute and helpful.

The Fructan Jingle
by Katy Watts

When you wake at crack of dawn
Graze your pony on your lawn
But sugars rise in afternoon,
For foundered ponies, this spells doom

When frosts cause fructans to increase
Your ponies grazing now must cease.
Hold off a day, or maybe more,
Or else your pony may get sore.

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