Safer Grass

Fructans are high in grass right after a rain - TRUE or FALSE?

By Madalyn Ward, DVM


Grass is safe for horses. True or false? Well, it depends. I have learned a lot in the last few months about why grass can cause laminitis in susceptible horses. Some of my previous beliefs have been proven incorrect. Here is a test to see where you are in your knowledge. To find out more visit

1. Grass founder can happen after eating too much fresh green grass. TRUE. Eating too much grass can cause laminitis for two reasons. Digestive upset can occur from the excess carbohydrates (sugars) in the grass. Carbohydrate overload is a common cause of laminitis. Another reason for laminitis is the grass may contain high levels of a form of sugar known as a fructan. Fructans are considered non structural carbohydrates which plants produce in larger quantities when stressed. Fructan is similar to starch but the horse does not have the ability to break it down in the same way it does starch. Therefore the fructans end up in the large intestine where bacteria multiply and break down the fructan. The overgrowth of the fructan digesting bacteria upsets the normal balance in the digestive tract resulting in toxins being formed which lead to laminitis.

2. Fructans are high in grass right after a rain and not a problem during dry weather. FALSE. Fructans are produced following photosynthesis which is dependant on sunlight. Fructans are actually lower in grass during cloudy weather.

3. Laminitis from grass is only a problem in the spring and fall when the grass is lush and growing the most rapidly. FALSE. Fructans can show up in grass when it is stressed. This can be from drought or frost as well as during rapid growth.

4. Not fertilizing or maintaining your pasture will make it safe for horses susceptible to laminitis. FALSE. While I certainly prefer horses be on non fertilized native grass pasture, grass grown in nutrient poor soil can produce fructans due to stress on the plant. Because excess carbohydrates in grass are depleted as the plant is growing, regular pasture mowing will help control carbohydrate levels as well as control weeds.

5. Overweight horses and insulin resistant horses are the most susceptible to laminitis from grass. TRUE. Overweight horses can get a mechanical form of laminitis from the excess pressure on the laminar attachments. On the other hand an insulin resistant horse does not need to be overweight to have problems from excess carbohydrates in grass. Signs of insulin resistance include a cresty neck and unevenly distributed fat over the withers and tailhead.

6. Hay never contains harmful carbohydrates. FALSE. Hay can contain up to 30% non structural carbohydrates depending on what the conditions were at the time of baling. Hay cut in the afternoon on a sunny day will have higher fructan levels than hay cut in the morning on a cloudy day. Hay which was rained on between cutting and baling will have the lowest levels of fructans. Cool climate grasses such as fescue, bromegrass, ryegrass, orchardgrass, and quackgrass tend to have higher fructan levels where drought resistant grasses such as bermuda, switchgrass, bluestem and Indian grass are lower in fructans. All pasture grasses have the potential to contain high levels of fructans under the right conditions.

7. The safest time to turn out susceptible horses on pasture is late night and early mornings when the grass is not stressed by drought, frost or in a flowering stage of growth. TRUE. Grazing muzzles are another alternative for horses which must be left out on pasture. Ideally having a dry lot to keep horses during critical times is best. If hay causes a problem consider soaking the hay for 30 minutes to 1 hour to wash out some of the carbohydrates before feeding. Beet pulp is another safe source of fiber for horses very sensitive to carbohydrates.

Many thanks to Kathryn Watts for her very informative website Many horses will be spared the horrors of laminitis as a result of her sharing of this information. If your horse has already been a victim of laminitis, you can find holistic options for treatment in my laminitis e book at


© Madalyn Ward, DVM, 2004 All Rights Reserved


About the author:

Madalyn Ward is a holistic veterinarian who operates Bear Creek Veterinary Clinic in Austin, TX. She has been on a holistic path since 1989 and has recently developed the 'Healthy Happy Horse' resource group to offer support to horse owners wanting to be proactive in the holistic care of their horses. Visit her informative website,, to learn more about horse care issues such as hoof care, supplements, nutrition, horsemanship, and general health.


For more information:

For additional help with the items mentioned in this checklist, visit Holistic Horsekeeping at Check out the Healthy Happy Horse Resource Group. It's a great way for you to plug into a community of educated horse people concerned with keeping their horses as healthy and happy as possible! The site also offers several ebooks on topics related to this article.


Madalyn Ward, DVM

Bear Creek Veterinary Clinic
11608 FM 1826, Austin, Texas 78737