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What is Setaria Poisoning?

Setaria is a tall perennial that is considered a tropical plant because of the climate of its native Africa. It has a cylindrical spike-like panicle and an inflorescence structure that will vary in color from purple to brown. There are multiple subspecies of setaria that will cause the same poisoning and be just as fatal if left untreated.

In as little as one month of grazing on setaria, a horse can begin to exhibit symptoms of nutritional secondary hyperparathyroidism or big head disease which is indicative of a calcium deficiency. The most noticeable symptom is well pronounced facial swelling.

Setaria grass is native to Africa but is also a common plant found in Australia and it has migrated to other parts of the world. It is also known as African bristle grass, golden bristle grass, golden millet, South African pigeon grass, Rhodesian grass, capim-setaria and napierzinho.

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Symptoms of Setaria Poisoning in Horses

It can sometimes be difficult to tell if your horse is suffering from plant poisoning until it is too late. Carefully watching your horse for any symptom that could indicate they are ill is important to seeking timely medical treatments for them. If you notice that your horse is exhibiting odd symptoms or is acting ill, remove them from their pasture and put them in a clean, well bedded stall. Keep all food away from them including treats, hay and grain. Symptoms to watch for include: 

  • Weakness
  • Lethargy
  • Depression 
  • Muscle tremors
  • Collapse
  • Swelling of the face (indicative of big head disease)
  • Kidney failure

Causes of Setaria Poisoning in Horses

All parts of the setaria plant are toxic to horses, especially when large amounts are eaten. High levels of oxalates will accumulate in your horse’s body and cause them to begin experiencing kidney failure. 

As the kidneys begin to fail, your horse will start to have a calcium deficiency and they will develop nutritional secondary hyperparathyroidism or big head disease. Mares and foals are more susceptible to developing big head disease from setaria poisoning.

Diagnosis of Setaria Poisoning in Horses

Once your veterinarian arrives they will ask you about the symptoms that you have witnessed and about your horse’s medical history and diet. If possible, have samples of your horse’s feed, hay and any suspicious plants found in their pasture for your veterinarian. 

A full physical examination will be done, paying close attention to any swelling of the face. Your veterinarian will also do a complete blood count, or CBC, a urinalysis and a fecal examination. These tests will rule out other possible illnesses or conditions and help your veterinarian determine what is causing your horse’s illness. 

Your horse’s kidneys will be tested to look for elevated or decreased kidney function. This will indicate whether or not the toxins have progressed through your horse’s body and are causing kidney disease.

Treatment of Setaria Poisoning in Horses

Your veterinarian will set a treatment plan in place for your horse which will include supportive care and intravenous fluids to flush the toxins quickly from the kidneys and out of the body. Activated charcoal may be given by mouth if your horse has recently ingested setaria, but generally setaria poisoning is a result of continual ingestion of the toxic plant over a period of time and the activated charcoal will not help.

There is no antidote for setaria poisoning. Your veterinarian will treat the symptoms as they present. Daily calcium supplementation may be prescribed if your horse is exhibiting signs of big head disease. Your veterinarian will want to closely monitor your horse’s kidney function during treatments to ensure that no damage is being done.

Recovery of Setaria Poisoning in Horses

Your horse’s prognosis will depend on the amount of toxins that have been ingested and how quickly medical treatments were started. Once your veterinarian has done an assessment of your horse and begun treatments they will be able to give you a more accurate prognosis.

Pasture management is essential in keeping your horse from eating things that could be toxic to them. Complete a weekly walk through of your horse’s pasture and look for any plants that could cause your horse to become ill. If you are not sure about a specific plant, take a sample into your veterinarian. They will help you identify the plant and whether or not it is poisonous to your horse. Use a pasture safe herbicide to eliminate any plant that is toxic if you are unable to pull it completely out by the roots.