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The danger of the oak processionary caterpillar for your dog

The danger of the oak processionary caterpillar for your dog

Written by Sjoerd | Content Specialist | March 27, 2026

The processionary caterpillar is not only dangerous for humans, but also for our pets, especially our dogs. Unfortunately, the problem with the oak processionary caterpillar seems to be increasing every year. The symptoms caused by this caterpillar are mainly due to the urticating hairs they spread. In this blog article, you can read more about this caterpillar and tips to prevent your dog from developing symptoms caused by it.

In addition to the oak processionary caterpillar, the brown-tail moth caterpillar is also found in the dune areas. This caterpillar also has urticating hairs and causes similar symptoms to the oak processionary caterpillar. The information in this blog therefore also applies to symptoms after contact with the brown-tail moth caterpillar or other caterpillars with urticating hairs.

What is the oak processionary caterpillar?

The oak processionary caterpillar is the larva of a moth. This moth lays eggs in the tops of mainly oak trees. The eggs overwinter there. From mid-April to early May, the eggs hatch. This can happen earlier if the winter has been very mild. After several moults, the caterpillars gather in groups. They can then form large nests on the trunk and branches of the oak tree. After moulting three times, the caterpillars develop urticating hairs. These hairs cause the health complaints.

What does a nest of the oak processionary caterpillar look like?

The nests of the processionary caterpillar are dense webs made of shed skins, urticating hairs and caterpillar droppings. The caterpillars move in procession in long lines in search of food in the tops of the trees and can strip the trees completely bare.

Where is the processionary caterpillar found?

The high temperatures we have experienced in recent years during spring and summer have led to the spread of the oak processionary caterpillar. Unfortunately, there are more caterpillar species that can cause health problems. For example, the pine processionary caterpillar, which lives in other types of trees. Another caterpillar is the brown-tail moth caterpillar, which occurs in dune areas.

What symptoms can occur in dogs due to the processionary caterpillar?

As mentioned, the symptoms in humans and animals are mainly caused by the urticating hairs. Symptoms are mainly reported in horses and dogs. In this article, we focus on dogs.

Dogs often ingest large numbers of urticating hairs. This can cause the following symptoms:

swelling of the tongue and lips
inflammation of the oral mucosa
inflammation of the eyes
breathing problems
skin issues (less frequent than in humans due to the dog’s coat)
if your dog has been exposed to a large number of urticating hairs, a severe and life-threatening allergic reaction may occur and your dog may even die as a result

Dogs may start drooling and develop watery eyes. They may have difficulty swallowing and may even gag and vomit. The damage in the mouth can be so severe that part of the tongue may die.

What should you do if your dog has symptoms?

If your dog shows symptoms as described above, you should have your pet examined by your veterinarian as soon as possible. The veterinarian can help reduce swelling, pain and vomiting. If there are urticating hairs in the mouth, it should be thoroughly rinsed with water. Hospitalisation at a veterinary clinic may be necessary and treatment can take several days. It may even take weeks for all symptoms to disappear.

What can I do to prevent symptoms for myself or my dog?

Do not sit under or near an infested tree. In general, avoid contact with processionary caterpillars and their remains, especially as dogs can easily sniff them.
Cover your neck, arms and legs if you go to an area where oak processionary caterpillars are present. Do not rub or scratch the skin after contact with the hairs, not for yourself and not for your dog. This will worsen the symptoms. Rinse with water.
Do not touch the caterpillars, old hairs, nests or shed skins. Explain this to children as well.
The urticating hairs remain present well into August, so stay alert. Avoid areas with nests as much as possible. The hairs can spread widely through the wind.
Report infested trees to your local council if there is not yet a warning ribbon around the trunk.

Which products can you keep at home to prevent symptoms or provide first aid to your dog?

It remains important to visit a veterinarian as soon as possible if your dog has come into contact with the urticating hairs of the caterpillar. Sometimes this is not immediately possible, and in that case it is helpful to know what you can do yourself to help your dog.

If you suspect your pet has been in contact with the hairs but shows no symptoms, you can at least rinse or wash your dog’s coat thoroughly. First rinse the coat with water only to remove any loose hairs. Using adhesive tape can also help. Afterwards, you can wash your dog with a caring or soothing dog shampoo. Suitable caring shampoos include Douxo Care dog shampoo and Dermazyme Calm dog shampoo. If the skin is already irritated, you can also use special shampoos such as Douxo Calm dog shampoo.

Make sure to rinse the head and possibly the mouth with lukewarm water. Prevent water from entering your dog’s throat and ensure your pet does not drink the water. To rinse the eyes, there are special solutions such as Ophta-Clean and AA Eye Cleanser. These products are often physiological or have the same pH as tear fluid, so they do not unnecessarily irritate the eyes.

The skin around the eyes is also extra sensitive. You can rinse this with the products mentioned above. If you do not have these products, rinse with plain water. Repeating the rinsing of your dog’s eyes several times is important. Try to rub as little as possible, as this can spread the hairs and cause more irritation. After rinsing, you can protect the eyes with a caring ointment with vitamin A, such as Ophtosan eye ointment for your dog. To soothe red and irritated skin, you can use Processionary caterpillar gel or Amos Horse Balsam. You can also support your pet with Puur Bombyx.

Remember that the above advice is only intended as first aid or if you cannot immediately visit a veterinarian. It remains important to contact your veterinarian immediately if you suspect symptoms caused by the oak processionary caterpillar.