Holly Poisoning in Cats

Holly plants are well known for their shiny, dark green leaves and bright red berry-like drupes. They are often used as ornamental plants, and holiday decorations because of these characteristics. They can be found in gardens as well, in the form of trees, shrubs, or climbing plants. 

When eaten, the leaves, berries, bark, and seeds are all mildly toxic to most mammals. Holly contains multiple toxins including saponins, methylxanthines, cyanogenic glycosides, and theobromine alkaloids. A cat's liver has a difficult time digesting plant glycosides, as once the sugar portion of the molecule is stripped away, the chemical becomes harmful to the body. Theobromine alkaloids are very similar to caffeine and cause an overstimulation of the central nervous system. The spines of the leaves can also cut the oral tissues when chewed. Poisoning by holly is generally not fatal, and the plant has even been used medicinally by humans or as a tea for its caffeine-like effects. 

Depending on how much plant material has been consumed, symptom severity will usually be mild to moderate. Gastrointestinal upset is the most common response after holly has been eaten. All signs to watch for include:

• Nausea
• Vomiting 
• Diarrhea
• Excessive drooling 
• Smacking of the lips
• Cuts in the mouth or red gums/tongue
• Head shaking
• Abdominal pain
• Loss of appetite
• Drowsiness 
• Dizziness 
• Quickened pulse
• Low blood pressure 

Types 

Holly trees and shrubs fall within the Ilex genus of plants. There are about 480 species within this family. Here are some of the most common four. 

• European Holly (Ilex aquifolium) - This is the holly we traditionally use in Christmas decorations, known for its shiny, spined leaves and bright red berries. It's also called English holly, common holly, and Christmas holly. It's native to Europe, Asia, and Africa, but it can also be found growing in gardens across the United States. 

• American Holly (Ilex opaca) - American holly is an ornamental plane native to the southern and eastern United States used as a substitute where European Holly does not grow well. It is similar in appearance but has less shiny leaves than its European cousin. 

• Common Winterberry (Ilex verticillata) - The winterberry is appropriately named for the pop of red color the berries produce on a winter landscape. This shrub does well in bogs or swamps, and it is native to eastern North America. It has different names depending on the region, such as coralberry, black alder, Michigan holly, Canada holly, deciduous holly, fever bush, Virginian winterberry, brook alder, and swamp holly.

• Japanese Holly (Ilex crenata) - Japanese Holly a popular bonsai plant with rounded, glossy, dark green leaves. This species is native to China, Japan, Korea, Sakhalin, and Taiwan. It also goes by the alternative common name box-leaved holly.

Holly poisoning can occur when a cat eats any part of the holly plant. Due to the fact that holly is a very common seasonal decoration used at Christmas time, indoor cats may be just as much at risk of exposure to the plant as outdoor cats. Holly can be found growing in gardens year-round. Most cats are deterred from eating their foliage due to their sharp spines and the very bitter taste of the leaves, but even a few bites of this plant can cause a reaction.  

If you suspect your cat has been poisoned from eating holly, bring it in to be professionally assessed by your veterinarian. You may be asked to provide the cat's medical history to help rule out possible causes of digestive distress if symptoms have begun but you did not witness the cat eating any plants. If you did see the cat eating a plant, but are unsure of what it was, bring a small clipping with you so that the vet may identify it. If it is near Christmas time, your vet may ask if you have brought holly into the home. You may also be asked if you allow your cat outdoors or not.

The veterinarian will then perform a complete physical examination, checking for all symptoms of illness. They will look closely at the mouth for signs of irritation. A stethoscope will be used to listen to the heart and lungs. The vet may find a rapid heartbeat paired with lowered blood pressure. Blood will be taken for certain tests to be run, including a complete blood count and a biochemical profile. This will give a more complete picture of the cat's overall health. Urinalysis may also be needed to assess how the organs are functioning within the body.

The amount of treatment needed will vary based on the severity of the symptoms and the amount of plant material that has been consumed. Hospitalization may be required in extreme circumstances.

Clear the mouth 

The oral cavity should be flushed with water to remove all remaining plant material, including any potentially painful bits of spiny leaves. 

Remove toxins 

The cat may be made to vomit using hydrogen peroxide to remove any holly in the stomach. If this cannot be done, a gastric lavage (stomach pump) might be performed instead to remove all remaining plant material from the stomach, especially if a large quantity was ingested. Activated charcoal may be given to the cat to help absorb the toxins in the digestive tract and trap them so that they can safely pass through the body and be expelled as waste.

Fluid replacement

If the cat has become dehydrated from excessive vomiting or diarrhea, intravenous fluids will be administered to rehydrate the animal.

Cats who have been poisoned by holly tend to make a full recovery after the toxins have passed through the body. No lasting health problems should exist after the illness. Keeping your cat indoors can help prevent them from coming into contact with holly growing in people's gardens.

If you use holly as a Christmas decoration, remove all of the berries prior to bringing the branches into your home as the berries dry out when indoors and often fall to the ground where they are very accessible to pets. Using synthetic holly is another option to make your home look festive while keeping your cats safe.

Holly poisoning can be expensive to treat. If you suspect your cat 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!

Cost of treating holly poisoning: $100-$500