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Spring Grass Can Cause Founder

When pastures are covered with a foot of snow, the temperature dips to minus 30, and you’re packing feed to horses, it is hard to worry about the lush green spring pastures. However, now is the time to plan for your horses’ return to those pastures without risking a bout of spring founder.

Founder (laminitis) is always a concern when horses go from a hay-based feed to early pasture. Spring grass contains high levels of carbohydrates, especially a sugar called fructan. Consumption of large amounts of fructan is similar to grain overload and can cause spring founder.

The early grass is much higher in moisture content (75-85 percent). As well protein (greater than 20 percent), energy, vitamins, and minerals, are also higher than other times of the year. Energy and protein content of foliage can be as much as 50 percent higher in early vegetative growth, compared to late summer growth.

Horses fed on pasture year round usually adjust to new grass as it grows. Hay still provides the necessary nutrition but they graze the grass as it grows and adjust to it gradually. Most management problems occur when horses have been confined, fed a hay-grain ration through the winter, and then abruptly are turned out on spring pasture.

Signs of acute laminitis include:

Lameness, especially when a horse is turning in circles

Heat in the feet

Increased digital pulse in the feet

A reluctant or hesitant gait (walking on egg shells)

A “sawhorse stance” with the front feet stretched out in front to ease pressure on the toes and the hind feed “camped out” or positioned further back than normal so they bear more weight.

Experts have suggested numerous ways of minimizing the risk of founder when horses go on to early grass, although I couldn’t help but make comments based on our own practical experience.

1. Feed hay immediately before they are turned out on pasture during the adjustment period. They are less likely to overeat when if their stomachs are full

(Worth a try but I don’t have much faith in this. I wouldn’t count on horses not eating lots of grass even if they have just eaten hay. Would you be less likely to eat pie if you had just eaten potatoes?).

2. Restrict grazing time. Horses can be allowed to graze only about 30 minutes once or twice a day the first day and, on subsequent days grazing time is increased by five or ten minutes per day until they are grazing four to six hours a day.

(We found that activities such as going to work every day makes it difficult to follow such precise timing.)

3. The easiest method of avoiding grass founder may be to have horses on pasture before the grass begins to grow. They will move around and find the first green shoots and adapt naturally to the high carbohydrate diet.

(We kept our horses on the pasture all year and fed hay until there was sufficient grass.)

If a bale of straw or low quality hay is left on pasture, most horses will eat some of it as they adjust to the grass.

And note to this lush grass condition isn’t limited to the spring. Increased autumn rainfall can lead to rapid plant growth and lush pasture with the nutritional value similar to that of spring pasture, and the health concerns of obesity and laminitis are again a major concern.

Many horses that develop laminitis recover and go on to lead long, useful lives. Unfortunately others suffer such severe, irreparable damage they are often for humane reasons euthanized.

Georgina Campbell is a freelance writer and a long time horse enthusiast living at Lamont, Alberta

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