Moldy hay can be dangerous to horses. Horses fed on moldy hay can suffer from colic, or in severe cases, die from the toxins called mycotoxins.
Wet hay or hay stored in damp conditions can lead to the growth of mold. Humid weather can also cause the rapid onset of mold. The mycotoxins from mold can be toxic to horses. In mild cases horses might suffer from colic, lack of appetite, change in weight, and diarrhea. Horses may also salivate, which is also called the slobbers, or tear excessively.
If the nervous system is affected horses may tremble, shake their heads, behave erratically or collapse. However, horses can recover quickly when the contaminated hay is removed. Recovery is usually within a few weeks. Symptoms of mycotoxins poison can also be severe, and can result in death. Horses may have fever, blood in the stool, spontaneous abortions, birth defects, breathing difficulties, and liver and kidney failure.
Pregnant mares are particularly susceptible to moldy hay, leading to still births, abortions, foals in poor condition. The fertility of male horses can be affected, leading to weak sperm. How horses react to mold depends on the type of mycotoxins. Horses can also fall ill by breathing in mold spores from dusty straw beds in their stables or barn, and in the process their lungs are damaged, in some cases permanently.
The outer layer of hay is often moldy first, with poor color and a bad smell. Often the outer layer may be good, but a deeper inspection may be required. Checking hay in bright light should reveal if it is edible for horses. Very dusty hay is sign of mold and is not safe for use. Good quality hay is soft, green and pleasant smelling. Moldy hay smells musty and has whitish to grayish dust and must be discarded. Very compact and heavy hay is a sign of mold.
Bales of hay from cattle feedlots have higher levels of mold and are not suitable for horses. Cattle have no problems feeding on moldy hay, but the digestive system of a horse is much more sensitive. The dangers of moldy hay can be reduced by careful checking and buying from a reliable supplier. Hay on your premises must be kept dry at all times to prevent the formation of mold. Hay can be kept dry by increased ventilation, bigger distances between bales and reducing the size of bales. Any covering should be high enough so there is enough space for moisture to evaporate.
I hope this post was helpful and more information on mycotoxins can be found here.
Photo source: Wikimedia Commons
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