Processionary caterpillars are something that can be fatal to animals. You may think a caterpillar can do no harm to either animals or humans but there is one that you may come across in warmer climates. There are reports of them being found in the South of  England and there have two main names, the Processionary caterpillar or the Pine Processionary Moth Larvae.

Moths lay their eggs in pine trees and you can see the nests, which look like small tennis ball sized cocoons that appear to be made of cobwebs. During the winter, these cocoons develop into the larvae.  The caterpillars become active and are a risk from January to April, sometimes later. The amount and exact timings will depend on the weather conditions in that year.

When they leave the nest, they make their way down the tree in a line, following each other, which is why they are called Processionary caterpillars. They are looking for food and you can see them in lines, rather than as single caterpillars. It has been known for these lines to be many metres long, but some are just 10-50 caterpillars long depending on a number of factors.

So why are these caterpillars a problem?

They secrete an acidic poison, which causes severe infections.  Dogs are attracted to the caterpillars and they often playfully hit them with their paw or sniff them.  This causes the caterpillars to secrete the acidic poison which causes a painful sting on the skin of the animal. To ease the pain the dog licks the sting, spreading the poison to the mouth where the poison causes severe tissue damage,  affecting the airway and respiration.

Interestingly, cats rarely get affected as they seem to have an inherent fear of the caterpillars.

If you suspect your dog has come into contact with these caterpillars then get them to the vet immediately. The signs are excessive salivation and symptoms of an allergic reaction. The blood pressure will drop, and this can lead to shock and even death. The tongue will also appear to be swollen.

Where a dog survives this initial stage, they often develop an infection of the tongue or throat and in time gangrene can occur which causes parts of the tongue to fall off or require removal by a vet.

With first aid, the first thing to remember is that this toxin will hurt you as well so wear gloves and try to flush the animal’s mouth out with plenty of water and get them to the vet as soon as possible, calling the vet to warn them you are on the way.  Some vets advise that if you are travelling to risk areas to carry antihistamine tablets to try and slow the reaction before you get professional help.

If you are taking your dog to a risk area, do your research to find out what the risks are and where local vets are.  Avoid taking them for walks in areas where there are pine trees, keep them on leads and try to not let them sniff the ground. Muzzling dogs while you are out will avoid the toxins reaching the mouth.

Finally, remember these caterpillars are not a large risk in the UK at the moment and trees can be sprayed to kill them. They are more of an issue if you take your dog on holiday abroad, but it’s certainly something to be aware of in order to protect your pet.