Tung Tree Poisoning in Dogs

The tung tree (Vernicia fordii) is a medium-sized deciduous tree which reaches up to 65 feet tall. It is the source of tung oil, an oil used as an attractive and non-toxic finish for wood, and grows naturally in China, Burma, and Vietnam. It was introduced in the United States in the early 1900’s and has since been labeled an invasive species in the southern states, particularly Florida. All parts of the plant, especially the nut, contain glycosides and saponins that can prove detrimental to canines when ingested. If your pet consumes any portion of this tree, contact your veterinarian or local emergency veterinary clinic right away.

Vernicia fordii, commonly known as the tung tree or tung oil tree, contains dangerous saponins and glycosides. Ingestion of this plant can be lethal, and should be treated as an emergency.

The tung tree is the source of tung Oil, an oil frequently used as a non-toxic wood finish. Although the pressed oil from the tung tree is non-toxic, the remainder of the plant contains saponins and glycosides that are present throughout the plant, but most concentrated in the seeds. 

• Cardiac arrhythmias
• Collapse
• Decreased heart rate
• Depression
• Diarrhea
• Drooling
• Hyperkalemia (high levels of potassium in blood)
• Increased heart rate
• Loss of appetite
• Lethargy
• Nausea
• Seizures
• Sudden death
• Tremors
• Unsteady gait
• Vomiting
• Weakness

Types

Vernicia fordii is a plant in the spurge family that is native to southern China, northern Vietnam, and Burma. It is most commonly known as a tung tree or tung oil tree but has also been called by the names China wood-oil tree and the kalo nut tree. The saponins and glycosides in the tung trees are not the only hazards to munching on this plant. The seeds or nuts of the plant also have been known to cause internal hemorrhaging and abrasions to the stomach. The sap also causes a dermatitis-like rash when it comes into to contact with skin.

• The toxins in the tung tree lie in the saponins and glycosides that are present in all parts of the plant
• The seed or nut of the tree has the highest concentrations of these compounds
• Saponins are compounds that act on the red blood cells and cause them to rupture
• Cardiac glycosides, also known as steroidal glycosides, disrupt the natural rhythm of the heart by acting on the force of the cardiac muscle itself

If you catch your pet consuming any part of the tung tree, the identification of the plant may be enough to posit an initial diagnosis. Information will be gathered regarding the amount of plant material ingested, what part of the plant was eaten, and how long ago this occurred, as these factors can help to determine the most effective treatment plan. If the ingestion of the item was not witnessed, the symptoms would prompt your veterinarian to take note of any inappropriate eating that your pet may have partaken in recently, in addition to any concurrent prescriptions or supplements that your dog has been taking. 

Some medications used to regulate the heart in both humans and canines incorporate cardiac glycosides as well, so information about these types of drugs is noteworthy. Drugs such as beta-blockers, steroids, and some chemotherapy agents may interact negatively with glycosides. There are blood tests available to detect the glycosides, as well as to monitor the levels of glycosides in the system. However, the cost of these methods limits their accessibility for veterinary diagnosis.

If it has only been a short time since ingestion your dog’s doctor may choose to induce vomiting or to perform a gastric irrigation. Once the plant material has been evacuated from your pet’s stomach activated charcoal is likely to be administered in an attempt to soak up as many of the noxious compounds as possible before they dissolve into the bloodstream. When the presenting symptoms indicate the involvement of the heart, antiarrhythmic drugs such as atropine sulfate, procainamide or lidocaine may be utilized, and the heart will be closely monitored. 

General supportive measures are likely to include intravenous fluids for dehydration and combinations of sugars and electrolytes to counteract any irregularities. Calcium should be avoided as an additive to the IV fluids when tung tree poisoning has occurred, as the calcium tends to enhance the effects of the glycosides involved. Supplemental potassium is also known to cause complications as it can increase the likelihood of hyperkalemia developing. Although digoxin-specific antibodies have successfully been used to treat glycoside toxicity in humans, it has not proven effective in canines or other animals. Injections of fructose have also been used experimentally to reduce serum potassium levels and heart irregularities.

As little as one nut has been known to be lethal, and the prognosis is guarded if this is the part of the plant that your pet ingested. The amount ingested, the size of the canine, and how quickly supportive measures are sought are key factors in mortality. Prompt, aggressive treatment in regards to any part of the tung tree plant will allow for a good chance of recovery. Providing a quiet, calm setting for your pet to return home to will help speed the return to normal. This is especially important when the heart is involved due to the glycosides present in the plant, in order to avoid further stress on the heart. 

Patients that are recovering from anesthesia given for a gastric decontamination may have coordination difficulties at first, and are often disoriented and bewildered. Isolation from other pets and from children may be wise until both the toxins and medication have fully cleared your companion’s system.