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What is Rubber Vine Poisoning ?

Rubber vine has grayish-brown stems and thick leaves that have a leathery look to them. The leaves are dark green and glossy on top and dull, pale on the bottom. When broken, the stems and leaves will expel a milky, white sap. Unripe seed pods will also expel the same milky, white sap when broken open. Tube shaped flowers that are white, purple or pink will appear in the summer. Brown or green pod-like fruits will form between summer and late autumn. There are flat, brown seeds in the fruit pods.

Rubber vine is a cardiac glycoside and can cause sudden death when ingested. Your horse should never be fed rubber vine and their pasture should be cleared of any rubber vine plants.

Rubber vine is known by several other names including Indian rubber vine, palay rubber vine, pichuco, purple allamanda, bejuco, caucho, estrella del norte and palo salomon. Its scientific name is cryptostegia grandiflora. Rubber vine is a woody perennial vine that is very common in tropical and subtropical regions, it is native to Madagascar. Sometimes rubber vine can be found in bush form.

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Symptoms of Rubber Vine Poisoning in Horses

It is very important that you seek veterinary attention immediately. Your horse’s life will depend on quickly diagnosing and treating rubber vine poisoning. While you are waiting for your veterinarian, remove your horse from their pasture and put them in a quiet stall away from any activity that could over-excite them and cause cardiac arrest. Symptoms to watch for include:

  • Sleepiness
  • Weakness
  • Colic
  • Diarrhea
  • Cold extremities
  • Cardiac arrhythmias
  • Profuse sweating
  • Difficulty breathing
  • Sudden death

Causes of Rubber Vine Poisoning in Horses

Rubber vine is a cardiac glycoside and sudden death can occur within minutes of ingesting the plant, many times while your horse is still in their pasture. Rubber vine contains the toxin cytotoxic cardenolides and digotoxin. When a cardiac glycoside is ingested, there are four organ systems that will be infected: cardiovascular, neuromuscular, gastrointestinal and respiratory. Preventing rubber vine poisoning is the only way to ensure that your horse does not become suddenly ill from these plants.

Diagnosis of Rubber Vine Poisoning in Horses

Your veterinarian will begin by conducting a full physical examination on your horse. They will ask you questions about your horse’s symptoms and their daily activities. If possible, have samples of your horse’s feed, hay and any suspicious plants in the pasture ready for your veterinarian. They may need to do an analysis, searching for toxins. 

Although there are no set diagnostic tests available for rubber vine poisoning, your veterinarian will be able to make a diagnosis based on the clinical symptoms that have presented and by ruling out other potential causes. A urinalysis, fecal examination and complete blood count, or CBC, will help determine what your horse is suffering from.

Treatment of Rubber Vine Poisoning in Horses

Treatments will begin immediately once your horse is diagnosed with cardiac glycoside poisoning. Your horse will need to be admitted to the veterinary hospital so supportive care can start. 

While hospitalized, your horse will be kept calm, to minimize the potential of a fatal cardiac disturbance. Too much stress will cause your horse to become excited and their heart rate to become irregular. Your veterinarian will have an IV inserted to make medication administration as stress free as possible. Fluid and nutrition therapy will also be provided through the IV. 

Activated charcoal will be given orally in large quantities according to your horse’s body weight. The activated charcoal will help absorb and bind any plant toxins that are still in your horse’s stomach. This will keep your horse from absorbing more toxins into their body. 

Many veterinarians will be given anti-arrhythmic medications to correct any cardiac abnormalities. Magnesium sulfate will need to be administered by mouth, not through an IV. Magnesium sulfate is used to treat ventricular arrhythmias. This will help keep your horse from going into full cardiac arrest.

Recovery of Rubber Vine Poisoning in Horses

Your horse’s prognosis will be very guarded when diagnosed with rubber vine poisoning. Your veterinarian will give you a more specific prognosis for your horse once treatments have begun and they see how well your horse is responding. Permanent heart damage may be a result of rubber vine poisoning and your horse will not be able to complete the work or daily activities that they were able to do prior to their illness. Horses with permanent heart damage will be pasture horses and not be expected to do more, exercise should be limited. 

Be sure to practice proper pasture maintenance by being aware of what is growing in your horse’s pasture. Do weekly a weekly walkthrough, searching for any plant that can harm your horse. When you find rubber vines or other poisonous plants, remove your horse immediately from the pasture and begin killing off the offending plants.