The processionary caterpillar: A silent threat to our dogs
Tuesday, April , 2026
Care and advice
The arrival of spring brings with it a natural beauty that many of us enjoy, but it also hides dangers for our dogs. One of these dangers, perhaps less well known but equally worrying, is the processionary caterpillar, which can cause serious harm to dogs and other animals.
What is the pine processionary caterpillar?
The pine processionary caterpillar (Thaumetopoea pityocampa) is a species of caterpillar commonly found in temperate regions of Europe. These caterpillars are known for their gregarious behavior, forming processions in single file as they move from their nests in trees to the ground, where they burrow to pupate and become moths.
Why are processionary caterpillars so dangerous to dogs?
Although processionary caterpillars appear harmless at first glance, they are extremely dangerous due to their natural defense mechanism. These caterpillars are covered with thousands of tiny stinging hairs that contain a highly irritating toxin called thaumetopoein. This substance acts as a powerful allergen, capable of triggering severe allergic and toxic reactions in dogs, other animals, and even humans.
What makes the toxin thaumetopoein so dangerous?
Thaumetopoein mainly affects the mucous membranes, skin, and respiratory tract. When a dog approaches a processionary caterpillar, out of natural curiosity, it may sniff it, lick it, or, in some cases, ingest it. This contact triggers the caterpillar's defense mechanism, releasing its stinging hairs into the air or directly onto the animal. These hairs are so light that they can even be carried by the wind, increasing the risk of exposure.Effects of contact on dogs:
1. Immediate irritation and intense pain: Contact with stinging hairs can cause severe irritation, resulting in intense pain in the affected area, especially on the tongue, lips, and snout.
2. Severe allergic reaction: Exposure to the toxin can trigger serious allergic reactions, including swelling of the tongue and throat, which can obstruct the dog's airways and cause suffocation. 3. Tissue necrosis: In cases where the tongue or soft tissues suffer severe inflammation, necrosis (tissue death) can occur. If not treated immediately, parts of the tongue may detach, leading to serious and irreversible complications. 4. Anaphylactic shock: In the most critical situations, contact with the caterpillar can trigger anaphylactic shock. This reaction is life-threatening, as it affects the dog's cardiovascular system and can lead to death within minutes if urgent veterinary treatment is not received. -Respiratory problems: If the stinging hairs are inhaled, they can irritate the lungs and airways, causing breathing difficulties and, in severe cases, respiratory failure.-Eye injuries: Contact with the eyes can cause conjunctivitis, severe eye inflammation, and even loss of vision. -Digestive problems: If the dog ingests the caterpillar, it may suffer from vomiting, severe diarrhea, and ulcers in the gastrointestinal tract. Dogs explore the world through their sense of smell and mouth. This natural curiosity leads them to approach processionary caterpillars, increasing the risk of direct contact. In addition, their snout, tongue, and throat are highly sensitive areas, which allows the toxin to act quickly and cause severe damage. Detecting whether your dog has had an encounter with a processionary caterpillar can be crucial in order to act quickly and avoid complications. Here are some signs to look out for: -Symptoms usually appear suddenly. In mild cases, after minimal contact, you may notice localized inflammation of the lips and slight irritation of the tongue and oral mucosa, manifested by excessive drooling. In addition, dogs affected by itching often appear restless and rub their snouts against the ground. Other symptoms may include stomatitis and excessive drooling.-When contact is mainly with the tongue, symptoms may be more severe, with stomatitis and inflammation of the tongue ranging from a half-open mouth with excessive salivation to a swollen, purple tongue that, over time, may become necrotic and partially detach. In these extreme cases, the animal's general condition is affected, even preventing it from eating or drinking, with risk of death.-Symptoms of processionary caterpillar poisoning in dogs can range from skin irritation and difficulty breathing to inflammation of the tongue and throat, vomiting, diarrhea, and even anaphylactic shock. In severe cases, exposure to processionary caterpillars can result in the death of the animal if not treated quickly. The first thing to do is to protect your hands with gloves, as the stinging hairs can also affect humans. If you don't have gloves to hand, you can use bags or other similar material. Wash the affected area with plenty of soap and water. If the water is warm, even better, as heat helps to deactivate the protein that causes the allergic reaction. It is crucial to take the dog to the vet as soon as possible for treatment. Depending on the severity of the allergic reaction, the animal may need to be hospitalized. The best prevention is to avoid contact with processionary caterpillars. Here are some recommendations:Other associated risks:
Why are dogs particularly vulnerable?
How do I know if my dog has come into contact with a processionary caterpillar?
What can I do if my dog comes into contact with a processionary caterpillar?
How can I prevent contact with the processionary caterpillar?
-Avoid these areas on windy days, as nests may have fallen from the trees.
-Always carry plastic bags and water with you when you go for a walk in the countryside. They could be useful in an emergency.
-Use collars and leashes to prevent dogs from getting close to the caterpillars.
-Be alert for symptoms of poisoning and seek immediate veterinary attention if exposure is suspected.
The pine processionary caterpillar may seem harmless at first glance, but for our dogs, it poses a real danger. It is important that we be vigilant and take steps to protect our dogs. Remember, the safety of our dogs is in our hands.
