Holly Poisoning in Dogs

The Ilex genus of plants, more commonly known as holly plants, are found throughout the temperate and subtropical regions of the world. Often used as an ornamental plant due to the glossy, dark-green leaves and attractive red berry-like drupes (fruits), it is an especially popular decoration around Christmas time.

Unfortunately, holly leaves and holly berries are toxic to dogs. Although ingestion is generally not fatal, consuming several leaves or berries is likely to cause gastrointestinal distress, such as vomiting and diarrhea. The small spikes present on each leaf often prevent your pet from ingesting large amounts, but they can also cause pain and swelling in the mouth area when chewed.

Symptoms of holly poisoning can include:

• Diarrhea
• Excessive drooling
• Head shaking
• Loss of appetite
• Pawing at mouth 
• Spots of blood in mouth
• Vomiting 

Types 

There are more than 400 species of holly plant in the Ilex family. Some of the more common varieties used for ornamentation include:

American Holly (Ilex olpaca) - Native to eastern and south-central areas of the United States. It has bright red berry-like drupes and the leaves of the American Holly are conspicuously less shiny than its English cousin.

English Holly (Ilex aquifolium) - Also known as European holly, Christmas holly, and common holly, this variety is native to western and southern Europe, northwest Africa, and southwest Asia. It has bright red or yellow berry-like drupes, and shiny leaves with a leathery feel. This is the type of holly that is most commonly used in Christmas decorations.

Japanese Holly (Ilex crenata) - Popular as a bonsai plant, this species is native to China, Japan, Korea, Sakhalin, and Taiwan, and is also known as the box-leaved holly. It has black berry-like drupes, and glossy, dark-green leaves.

Oregon Holly (Mahonia aquifolium) - Also known as Oregon Grape, this evergreen shrub is native to northwestern America. It produces blue fruit and yellow flowers.

The holly plant contains small quantities of several chemicals and compounds that can be mildly to moderately toxic to your companion. Some of the naturally occurring compounds that can be found in the holly plant are:

• Caffeic acid
  
• Caffeine
• Caffeoyl derivatives
• Chlorogenic acid
• Feruloylquinic acid
• Ilicine
• Ilexanthin 
• Kaempferol
• Quercetin
• Quinic acid
• Rutin
  
• Theobromine

The spikes on the leaves of most holly plants will cause initial symptoms to show up almost immediately as the discomfort will cause excessive drooling and pawing at the mouth. In those cases, identification of the plant may be all that is needed to diagnose the cause of the trouble.

If only a small amount is ingested, further symptoms may not develop. Larger amounts may cause gastrointestinal symptoms to begin within thirty minutes of ingestion, or may be delayed for a few hours. In the event that your pet has consumed several leaves or berries, or the symptoms that are being displayed are more extreme than expected, your veterinarian may recommend that you pet visit the office.

The veterinarian will question you about whether your dog may have ingested any holly and will ask about any supplements or prescription medicine that your dog is on. A complete blood count, biochemistry profile, and urinalysis may be run to ensure there are no underlying disorders that need to be addressed, and any vomit will be examined for plant materials or other inappropriate eating.

What should I do if my dog eats holly? In many cases, treatment of holly plant ingestion can be handled at home with relative ease. It is important to contact your veterinarian before starting treatment to determine if either the amount eaten or the reaction to the toxin warrants a visit to the veterinarian’s office.

Your veterinarian may induce vomiting in your dog. Flushing of the toxins and any plant material from the mouth will help prevent further damage from swallowing the irritants.

Once the plant material has been cleared from the mouth area, clean, cool water can be used to ease mouth pain and to replace any fluids lost due to vomiting or diarrhea.

If a sizeable amount of the leaves or berries were ingested, supportive therapy may be provided by your veterinarian. This will include IV fluid treatment to prevent any dehydration or electrolyte imbalances as well as monitoring of the heart rate and rhythm. Poisoning from the holly plant is rarely severe enough to require a full gastric irrigation; however, activated charcoal may be administered to absorb any toxins still present in the stomach and anti-inflammatory medications may also be used to reduce swelling.

The prognosis from holly toxicity is usually excellent, but removal of the plant from the environment is recommended to prevent further events.

Fatalities should not occur but is theoretically possible in cases of severe dehydration caused by excessive vomiting or diarrhea, particularly in young or unwell animals. So, it is essential to ensure that your pet has sufficient access to clean water and perhaps some rehydration solutions, during their recovery.

The chemical theobromine, the toxic ingredient found in chocolate, is also present in holly leaves, though in very small concentrations. If very large amounts of the leaves or berries are ingested, it is important to watch for signs of theobromine poisoning as these symptoms may be delayed for several hours.

Holly poisoning can be expensive to treat. If you suspect your dog is at risk of holly poisoning, start searching for pet insurance today. Wag!’s pet insurance comparison tool lets you compare plans from leading companies like PetPlan and Embrace. Find the “pawfect” plan for your pet in just a few clicks!