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What is Sudan Grass Toxicity ?

Sudan grass toxicity can develop weeks to months after ingestion begins. Symptoms can suggest other possible issues before it leads to a rule out diagnosis of toxicity. For example, urinary incontinence or cystitis can lead the veterinarian to believe your horse is suffering from some type of renal related infection. However, the more severe symptoms such as ataxia issues related to the brain and spinal cord are indicative of a toxin like cause. The sooner you involve a veterinarian, the higher the chances your horse’s prognosis will remain fair to good. However, in severe cases, prognosis of recovery is guarded to poor.

Toxicity from Sudan grass, also known as sorghum toxicity, can be a life-threatening condition. Contact your veterinarian immediately if your horse is acting abnormally in any way.

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Symptoms of Sudan Grass Toxicity in Horses

Symptoms may include:

  • Incoordination
  • Posterior ataxia 
  • Urinary incontinence
  • Cystitis
  • Axonal degeneration
  • Myelomalacia or cerebellum
  • Myelomalacia of spinal cord
  • Urine scald leading to alopecia on hind legs
  • Abortions in pregnant mares
  • Death 

Types

Sudan grass is also known by the name sorghum. It is a drought tolerant plant commonly found in the Southwestern United States as well as in Australia. It is a leafy plant that has very quick regrowth. Sudan grass can be found in many pastures as a form of forage for horses. Sudan grass is one of the most common causes of poisoning from a sorghum grass.

Causes of Sudan Grass Toxicity in Horses

It is believed that Sudan grass causes a neuropathic and teratogenic manifestation. Suggested agents include lathyrogenic nitriles. Symptoms typically develop after the horse has grazed on the grass for weeks to months. It is believed the grass itself contains the toxic properties but not the seeds.

Diagnosis of Sudan Grass Toxicity in Horses

Your veterinarian will begin by performing a full physical exam on your horse. She will take note of any and all symptoms he is experiencing in order to come to a complete diagnosis. She will also collect a history from you as to what your horse has been eating, where he may have travelled recently, when his symptoms began, and how quickly they have progressed. 

She will also want to run some blood work to check how your horse’s organs are functioning. Blood work will begin with a complete blood count and chemistry panel. The results will indicate how the organs are filtering the toxin and what types of supportive therapies may be beneficial to begin. 

A urinalysis will also be beneficial to rule out other possible causes of the urine scald. Radiographs may also be beneficial to check for lesions on the spinal cord. If the radiograph does not show anything but it is still highly suspected, she may recommend an MRI or CT scan for a more thorough, diagnostic image.

Treatment of Sudan Grass Toxicity in Horses

Many veterinarians have had success in treating Sudan grass toxicity with a combination of sulfur supplementation and antibiotics. Other symptoms your horse is experiencing will determine the course of supportive treatment the veterinarian will recommend. Each case is unique so there is no definitive course of treatment in this type of toxicity. 

A variation of medications and ointments can be prescribed to treat your horse’s symptoms. Keeping him in a calm, quiet place will also be helpful. Mild sedation may be recommended if necessary to prevent the horse from accidentally hurting himself, you, or the veterinary staff. 

If there are lesions on his spinal cord, there is no treatment for the development. Some may consider surgical excision, but it is not recommended in most, if not all, cases. Also, you would likely need to see a specialist for the surgery since the spinal cord is delicate. If there are lesions in the brain, there may not be anything you can do for that either. Brain surgery is expensive and may be dangerous to your horse and the risks often outweigh the possible benefits.

Recovery of Sudan Grass Toxicity in Horses

Recovery of toxicity will depend on the severity of the symptoms your horse is experiencing. In cases of development of mild symptoms alone, prognosis of recovery is fair to good. In cases where ataxia has developed, prognosis greatly declines. In many cases, it has been documented the horse’s official cause of death is pyelonephritis, a life-threatening condition of organ scarring.

Be knowledgeable about the vegetation you have on your property and along fence lines of neighboring properties. Ask your veterinarian or a noxious plant specialist to take a walk through your paddocks and pasture for possible identification of plants hazardous to your herd.