Mycotoxins in Pasture: How to Identify Paspalum Ergot and What It Means for Horses
Big green paddocks can look ideal, but pasture is never just pasture.
Some grasses and legumes can carry fungal issues that harbour mycotoxins. Once ingested by grazing horses, these can contribute to a range of problems that do not always immediately point back to the paddock. That is why pasture identification matters. Knowing what is growing, what stage it is at, and whether fungal contamination is present can make a real difference.
One common grass worth watching closely is paspalum. When affected by ergot fungus, paspalum can create problems for horses ranging from photosensitivity to paspalum staggers.
Pictured above: Identifying Paspalum leaf (typical red tinge on edge) before going to seed
This guide looks at how to identify that risk, what signs may show up in horses, and what practical steps can help reduce exposure.
Mycotoxins in pasture are fungal toxins that can occur on certain grasses and legumes. One common example is paspalum ergot, a fungal infection affecting paspalum seed heads that can create problems for grazing stock.
What are mycotoxins in pasture?
Mycotoxins are fungal toxins associated with certain grasses and legumes. These fungal issues can occur on pasture plants and, once ingested by grazing stock, may contribute to a range of problems.
This is why looking closely at pasture matters. A paddock can appear green, thick and productive, but that does not automatically make it suitable for horses. Sometimes the issue is not the amount of feed. It is what is hiding in it.
Paspalum is a warm season C4 perennial grass that grows in clumps. It is commonly found in horse paddocks and is worth watching closely when seed heads emerge.
Why paspalum matters in horse paddocks
Paspalum is a common warm season grass, particularly through summer. It is a C4 perennial grass that grows as a tufted clump rather than spreading by underground runners. Each plant grows as an individual clump, which makes it easier to identify once the grass is familiar.
It tends to grow well on moist, fertile soils, which is one reason it becomes common in some horse paddocks. The main concern is not simply the grass itself. The issue is that paspalum is susceptible to paspalum ergot, and that is where the risk begins.
Paspalum ergot is a black fungal infection of the flowerhead. It makes paspalum seed heads sticky in summer and creates a toxic risk for grazing stock.
How to identify paspalum ergot
When paspalum is affected by ergot fungus, the seed heads develop a black fungal infection. One of the clearest practical signs is that the seed heads turn black and may also display a white fungus type growth.
Aside from the fungal issue, the seeds can easily become caught in and around horses' eyes as they are sticky. If paspalum is present in the paddock and seed heads are up, that is the point where a closer inspection is needed.
Horses affected by paspalum staggers may show muscle tremors, head shaking, uncoordination, and falling over when stressed or overstimulated.
What signs can affected horses show?
One of the better known problems associated with paspalum ergot is paspalum staggers. It is more common in cattle, but horses can also be affected.
Signs can include:
- muscle tremors
- head shaking
- uncoordination
- falling over when overstimulated or stressed
These are not signs to ignore. If neurological type changes appear and paspalum with seed heads is present in the paddock, the pasture is worth checking straight away along with a call to your Equine Veterinarian.
Mycotoxins associated with paspalum can also contribute to photosensitivity, which may show up as greasy heel (pastern dermatitis), rainscald, or a sunburnt crusty nose and facial area.
How mycotoxins in pasture can show up externally
This is where pasture issues can become easy to miss.
Sometimes the first visible sign is not recognised as a pasture problem at all. Horses may show photosensitivity, greasy heel, rainscald-type skin irritation, or a pink, crusty, sunburnt look on the muzzle and face.
That is why it helps to look at the whole horse and the whole environment. If paspalum with ergot affected seed heads is present, the skin may be reflecting what is happening in the paddock.
Disruption to gut health can also show up in hoof health, which is why the feet should be monitored when horses are grazing questionable pasture.
Why hoof health also matters
Any disruption to gut health can potentially show up in hoof health as well.
That is worth keeping in mind when horses are grazing pasture that may be contributing to a mycotoxin load. Skin, behaviour, comfort and hoof condition do not sit in separate boxes. If something is not stacking up, the paddock is one of the first places worth checking.
To reduce risk, horses should be removed from affected paspalum pasture when seed heads are present, and the area should be managed by mowing, slashing or grazing before seed heads emerge.
What to do if paspalum ergot is found in pasture
The first step is straightforward. Remove the horse from the source.
If horses are grazing paspalum when seed heads are present, useful pasture management steps include:
- removing horses from the affected area
- mowing or slashing the pasture
- allowing clippings to break down and mulch back into the soil
- using frequent grazing or slashing to reduce future seed head emergence
If the pasture is not managed, the problem tends to keep circling back.
A toxin binder such as Mycosorb A+ may be used as part of management where pasture mycotoxins are a concern.
Where Mycosorb A+ fits in
Where pasture mycotoxins are a concern, a toxin binder may be considered as part of the broader management plan.
The key point is that pasture management still comes first. A binder does not replace removing the cause. It sits alongside a practical plan that addresses the paddock as well as the horse.
When horses are showing pasture related skin irritation, topical products can be used as part of a maintenance routine, while also dealing with internal health and the pasture source.
Where topical support fits
Once the pasture source has been addressed, the next step is supporting the horse externally.
If a horse has greasy heel, crusty pasterns, photosensitivity on the muzzle, or skin that is touchy and reactive, topical support can be used as part of a grooming routine. Depending on the area and the situation, that may include products such as Zinc Putty, Mud Suds, Hoof Powder, Equizinc or Hoof Spray.
The role of topical products is to:
- support hoof hygiene
- part of a hoof care routine
- helps maintain clean hooves
- grooming and maintenance
They are here to support routine care, not to replace pasture, poor hoof care cycles or nutritional management.
Final thoughts
Knowing what is growing in a paddock matters.
Paspalum is common, and paspalum ergot is worth taking seriously. When seasonal skin flare-ups, neurological signs, or general changes appear without a clear explanation, pasture should be part of the investigation.
If mould, fungus or mycotoxin related issues are suspected in pasture or hay, remove the source, review the grazing area properly, and contact an equine veterinarian if there are concerns.
Julie Wright
Dip. EPT, Cert. EMT
The Hoof Co
Leave a comment