Paspalum - A Potential Health Risk For Your Horse?

Paspalum has had a bumper year this year. Previously there has been little issue with Paspalum in the area where I live. Most people have a small amount in their pasture but as it is rather unpalatable, horses generally avoid it. But here is what to look out for if you think your horses are affected. 

Paspalum dilatatum is one of the Paspalum species of grasses and is referred to in New Zealand by the common name Paspalum. It is native to Brazil and Argentina, but it is known throughout the world as an introduced species and is a common lawn or pasture grass. Its rapid growth and spreading rhizomes make it an invasive pest in some areas. It is present in the southern half of North America, southern Europe, much of Africa, Australia, New Zealand, and many tropical and subtropical areas.

The seed heads of Paspalum contain fungus Claviceps paspali. This fungus has a toxic affect causing trembling of the large muscle groups; movements are jerky and uncoordinated. If they attempt to run, they fall over in awkward positions and can fall into fences or drains. 

Toxic infestations are most likely after humid, wet summers just like the one we are having this year! 

A sufficiently large single dose causes signs that last for several days or longer. Usually appetite remains good, and animals will eat if feed is provided but due to stress, stomach ulcers following such an even should be considered. Affected animals may be belligerent and dangerous to approach or handle. After prolonged exposure, condition is lost and complete paralysis can occur. The appearance of symptoms depends on the amount of seed heads in the pasture and the amount consumed. Experimentally, early signs appear in cattle after sclerotia (fungus in the seed head) at ~100 g/day has been administered for >2 days. Although the mature ergots are toxic, they are most dangerous just when they are maturing to the hard, black (sclerotic) stage.

It is only the seeds heads of Paspalum that are toxic. The leaf, stems and roots do not contain the toxic fungus. 

There is no medication available for the actual staggers but treatment may be needed for dehydration or injuries sustained during the staggers incident. Recovery will begin once the horse is no longer on the contaminated pasture.

First steps – 

• Removed your horse from the affected pasture even if you don’t know if that is the problem. Symptoms will only worsen if left on the toxic pasture. 
• Ensure the horse is kept quiet in a safe area free from obstacles – drains, jumps, water troughs or anything that the horse can fall over or in to. The company of another horse also will help keep the horse calm, if that is appropriate to that horse. 
• It is best call your vet. An oral sedative given daily can help hugely with keeping the horse calm. Ask your vet to supply a tube of this that you can use over the coming days. 
• Ensure the horse has 24 hour easy access to hay and water and offer small hard feeds throughout the day containing salt which will ensure the horse drinks properly and magnesium that will aid in keeping the horse calm. A toxin binder is also a good idea. 
• Check the horse regularly including night time. 

These steps above will ensure the fastest possible recovery for your horse. 

Ongoing it is best to eliminate Paspalum from your pasture if possible. Patches can be sprayed out and horse friendly grass seed can be sprinkled. 

It is common to think about mowing Paspalum to remove seed heads but those seed heads are still toxic when laying on the ground and probably even more likely to be eaten! If the seeds heads can be mown and collected this is an option but only at the end of its seeding time as no sooner the mowing is done, new seed heads will pop up. 

No easy solutions unfortunately!

This is another scenario, where having a dry lot area for when pastures are not suitable for your horses, can be by far the best solution.