Norfolk Island Pine Poisoning in Dogs

The Norfolk Island pine (Araucaria heterophylla) is not a pine tree at all, but a member of another ancient family of coniferous trees dating back to the Cretaceous period. It is also referred to as a star pine and a living Christmas tree, due to its tendency to grow symmetrically until after it has reached maturity. They are generally kept as houseplants or used as Christmas trees in most of North America as they are not particularly cold hardy, although they tend to thrive in warm beach environments such as Southern California and Florida. This plant is known to be mildly toxic to dogs when ingested, occasionally causing abdominal pain, vomiting, diarrhea, and lethargy.

The Norfolk Island pine (Araucaria heterophylla), is generally grown indoors as a decorative plant or cut down for use as a Christmas tree. Ingestion of this evergreen can cause gastrointestinal upset.

Most sources note that the ingestion of the Norfolk Island pine tree can cause signs of general gastrointestinal distress including:

• Abdominal pain
• Depression
• Diarrhea
• Excessive drooling
• Gagging
• Lethargy
• Loss of appetite
• Nausea
• Vomiting

The sap from the Norfolk Island pine is also known to induce a localized dermatitis in sensitive individuals. 

Types

Other notable trees in the Araucaria family include:

Cook pine (Araucaria columnaris) - This tree is native to New Caledonia, and is similar in many respects to the Norfolk Island Pine. It tends to grow thinner and taller than its cousin from Norfolk, and it has bark that peels off in thin paper-like sheets. 

Bunya pine (Araucaria bidwillii) - This species grows exclusively in Australia and is the last surviving species of the Bunya section of the Araucaria genus, a section that was widespread and diverse in the Mesozoic age. 

Monkey puzzle tree (Araucaria araucana) - This tree, an endangered “living fossil” that grows in Argentina and Chile, and is the national tree of Chile. It has tough, scale-like, triangular leaves with sharp edges rather than needles.

Most canines encounter the Norfolk Island pine indoors either as a decorative plant or as a Christmas tree. Although the plant itself is only mildly toxic, treatments designed to keep cut trees green longer or to simply improve the appearance of the tree may prove to be more dangerous. 

• Chemical treatments - Many Christmas trees are treated with paint and fire retardant chemicals before even leaving the tree lot
• Fertilizers - Fertilizers are used in the soil of live ornamental trees, as well as in the water in the stand for cut trees 
• Molds and mildews - Cut trees in standing water are prone to developing molds and mildews that can be quite dangerous to your pet’s health, both on the tree and in the standing water the tree is kept in

As the Norfolk Island pine is only mildly toxic, if your pet develops symptoms more alarming than minor episodes of vomiting or diarrhea, it is usually caused by the misidentification of the toxin affecting your pet, or a secondary disorder. The symptoms and signs that your pet exhibits will help determine the direction of for further diagnostic testing. Tests, including a complete blood count and biochemistry profiles, are likely to be requested at this time, as well as a urinalysis. These general tests will help to detect if there are any undetected toxins or chemical imbalances in the canine’s system.  

Your dog’s doctor will also complete a physical examination at this time, most likely concentrating on the abdominal area due to the symptoms. If the symptoms seem to indicate poisoning, you will be asked for further information about your dog’s recent health history and any opportunities they may have had for inappropriate eating. Any plant material that is vomited up or found in your dog’s stool will be evaluated to determine both its origin and toxicity levels. Tests to check for other possible chemicals or fertilizers will also be completed at this time in an effort to uncover the underlying cause of the distress.

In most cases, treatment for the ingestion of the Norfolk Island pine can be handled at home with relative ease. Contacting a veterinary professional before beginning any treatments is recommended so that you can get specific instructions for your pet’s situation. They will be able to help you determine if either the reaction to the toxin or the amount ingested warrants a visit to the veterinarian’s office. Treatment will be guided by the symptoms as well as by the ultimate diagnosis. 

Early therapy for dogs exhibiting gastrointestinal troubles generally involves the withholding food until both vomiting and diarrhea have ceased for approximately twelve hours. This method may be recommended by your veterinarian as it is designed to give the dog’s gastric muscles time to recover from the continual spasms caused by the vomiting. Small amounts of crushed ice and water should frequently be provided to combat dehydration while withholding food. Only soft, bland foods should be offered to your pet for at least twenty-four to forty-eight hours after the withholding period to avoid further gastrointestinal distress. If your pet is exhibiting signs of more severe distress, your veterinarian may recommend a visit to the office for decontamination and supportive treatments. Decontamination will likely include the administration of activated charcoal and may involve the gastric irrigation as well. Supportive treatments such as supplemental oxygen, or the administration of IV fluids will also be started at this time.

The effects of the unknown toxins in the Norfolk Island pine generally disappear within just a few hours after onset. If unusually large quantities of the tree are eaten, or if your dog is particularly sensitive to the compounds in the plant, extreme nausea and vomiting could occur. One of the biggest dangers with profuse vomiting and diarrhea is the risk of dehydration. Your pet should be consistently monitored for signs of dehydration such as exhaustion, sunken eyes, excessive panting, loss of elasticity in the skin,  and shakiness when standing. These symptoms may signal that the dog is in serious distress, and your veterinarian should be contacted for further instructions.