December 19, 2025, 5:37 am | Read time: 6 minutes
The so-called “Christmas Tree Syndrome” is a rare but dangerous phenomenon that is hardly known among dog owners. Dogs can actually be allergic to the Christmas tree. PETBOOK explains what signs to look for and how to react in an emergency.
Dachshund with Severe Breathing Problems
If your dog suddenly starts breathing strangely or swelling in December, it could actually be due to the Christmas tree. This was likely the case for dog trainer Dr. Kirsten Hinrichs. Her dachshund suddenly began to have trouble breathing one evening, as she shared on her Instagram channel, kirsten_souldogs. At the veterinary clinic, there was a quick suspicion that it could be asthma or an allergic reaction. Cortisone was supposed to help—but it didn’t. Hinrichs was very worried. She replayed the events of the past few days in her mind and remembered: They had set up the Christmas tree in the living room that day. After her research, it turned out that dogs can indeed be allergic to Christmas trees.
“Christmas Tree Syndrome” Exists in Dogs Too
What has been known in human medicine as “Christmas Tree Syndrome” is now increasingly coming into focus for pet owners. A study by Upstate Medical University showed back in 2011 that Christmas trees bring more than just the scent of resin and festive cheer. Researchers found more than fifty different molds on over twenty examined trees—some of which are known to trigger allergies. Particularly relevant are the types Aspergillus, Penicillium, Cladosporium, and Alternaria.
They can cause reactions in sensitive people as well as dogs, which in the worst case can lead to breathing problems. Although many questions remain unanswered, the study clearly showed that Christmas trees indoors pose an underestimated risk. The longer they stand there, the more spores they release into the air.
These Allergens Are in the Tree
A Christmas tree is often a huge, forest-scented mystery for our dogs. But this package of nature, moisture, and essential oils can cause problems. Mold spores from storage and transport sit on the branches, but pollen residues, plant proteins, and pesticides can also lead to severe allergic reactions.
The essential oils of the needles are also irritating, especially for dogs that curiously stick their noses into every branch. Even artificial trees are not automatically unproblematic because they release dust when unpacked, which can cause reactions in sensitive animals. In the end, all these influences create an invisible cocktail of allergens that can suddenly become too much for a dog.1
Also interesting: Why Dogs Are So Interested in Discarded Christmas Trees
Recognizing Allergic Reactions in Dogs
The symptoms can be as varied as our dogs themselves. Some clearly show that they are having trouble breathing, pant more heavily, or seem to need to catch their breath after every little movement. Others develop itchy or red skin, scratch more often, or even develop oozing spots.
There are dogs that suddenly get diarrhea or vomit, and those that simply disappear from the room where the tree is—a pretty clear sign that something there is unpleasant. You should be particularly alert if the symptoms coincide with the setting up of the tree or improve once it is removed. As strange as it sounds, a Christmas tree can be for a dog what a field full of pollen in May is for us.2
What to Do if the Dog Is Allergic to the Tree?
If you suspect an allergy, a simple first step is to create distance. Many dogs relax once they are no longer in the same room as the tree. An open window can also help reduce irritants in the air. Some owners decide to remove the tree entirely—a pragmatic solution that often brings the quickest relief.
However, if the dog shows severe allergic reactions such as difficulty breathing or facial swelling, the tree must be removed as quickly as possible. These symptoms can worsen and, in the worst case, lead to anaphylactic shock.
If you want to keep the tree, you can thoroughly rinse it outdoors and let it dry well before bringing it back into the living room. The decorations should also be checked, as they can contain additional irritants or dust. Gentle care products can temporarily help with skin problems. Medications like antihistamines or cortisone should always be handled by a veterinarian.
Christmas Trees Are Generally Dangerous for Dogs
The tree itself can already be a challenge—but the real dangers often lie in the details. Needles are sharp, can injure paws, irritate gums, or, if swallowed, even cause gastrointestinal problems. Tree water looks like an exciting new drinking source for some dogs, but often contains preservatives, resins, and bacteria that are anything but harmless.3
Then there are the classic Christmas risks: glass ornaments that can shatter, string lights whose cables might temptingly crack between teeth, and tinsel that—once swallowed—can lead to a life-threatening intestinal blockage. In short, the Christmas tree is a bit like a children’s birthday party without supervision for dogs—it can be wonderful, but also very quickly very dangerous.4
Cats and Dogs Can Also Develop a Pollen Allergy — These Are the Symptoms
Is My Dog Suffering From a Food Intolerance?
When Should I See a Veterinarian?
At the latest, if a dog is having trouble breathing, cannot be calmed, or appears apathetic, a visit to the veterinarian is absolutely necessary. Severely inflamed skin areas, persistent vomiting, diarrhea, drinking tree water, or the suspicion that needles or decorations have been swallowed are clear warning signs.
Important: Difficulty breathing is always an emergency—every minute counts here. And even if the symptoms persist after the tree is removed, it’s better to seek professional help too early than too late.
Conclusion
An allergy to the Christmas tree may sound exotic at first, but it is indeed possible—and sometimes even dramatic, as the case of Dr. Kirsten Hinrichs shows. Mold spores, pollen residues, and pesticides can trigger allergic reactions. There are also many other dangers that are quickly overlooked during the Christmas season.
Those who carefully observe their dog, pay attention to small changes, and are willing to clean or even remove the tree if necessary, can still enjoy the holidays in a relaxed manner. After all, the goal is for Christmas to be enjoyable for everyone in the household—including the animals that make our homes truly cozy.