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Are Caterpillars Poisonous To Dogs? 

Caterpillars aren’t generally a bug you need to worry about if you have a dog.

However, just like all things, there are exceptions to that generalization.

Here’s what you need to know about caterpillars’ health risks to dogs.

Can a Caterpillar Kill a Dog?

Although caterpillars are just chunky, squishy little bugs, they can pose a threat to Man’s Best Friend.

This is not to say that you should be afraid of every caterpillar that happens to appear in your yard.

Still, it’s best to be aware of the handful of species that could send your dog to the vet.

The caterpillar’s body part to watch out for in terms of safety hazards is the hair.

It may look cute and fuzzy from a distance, but these are dangerous little things.

Keep in mind that not all hairy caterpillars have poisonous hairs.

The specific type to avoid is “urticating” hair.

These are hollow hairs, resembling the structure and function of a porcupine’s quills.

At the base, each hair is connected to a poison sac.

After they pierce into whatever poor critter the caterpillar sees as a threat, they release the poison.

Effects include:

  • Mild to severe itching
  • Mild to severe pain
  • Skin problems (e.g., blistering, dermatitis)
  • Intestinal issues

These symptoms certainly aren’t pleasant for your pup, but luckily, they’re the worst it gets in most cases.

That is, unless your dog is stung by a pine processionary caterpillar.

This species poses an even greater threat to your four-legged buddy, as symptoms of its sting include:

  • Severe inflammation, particularly on the skin and mucous membranes
  • Hyperthermia (the body is abnormally hot)
  • Rapid breathing or other breathing problems
  • Turning blue due to poor circulation
  • Swelling of the tongue
  • Tongue necrosis (the tongue’s cells die off due to a lack of blood flow)

The pine processionary caterpillar’s poison may not kill your dog, but it is incredibly dangerous.

Luckily, it’s only a risk if you’re traveling to southern Europe, the Middle East, or North Africa.

They don’t appear to have any established populations in North America.

Still, if you suspect that your dog may have been stung by a processionary caterpillar, make sure it receives treatment within two hours for the best outcome.

Are Hairy Caterpillars Poisonous to Dogs?

As mentioned above, not all caterpillars are poisonous to dogs, even if they have hair.

With that said, it’s best to get to know a bit more about caterpillar hair.

This way, you’ll be able to discern when your dog is at risk of getting sick and when it’s not.

For starters, there are a few different types of hair that are considered “urticating.”

They grow in two primary ways, which may influence how they affect your dog.

First, they can grow as long, flexible hairs, much like yours or your pup’s.

On the other hand, they might be short, tough bristles.

These structural differences influence how the hair physically interacts with the dog’s skin.

For instance, in each of these two categories, long and short, you can further separate the hairs into those that puncture the skin merely for physical injury and those that inject venom.

Because of this function, the latter hairs are also known as “envenomating hairs.”

Some hairy caterpillars will only hurt your dog physically.

In these cases, the hair will get stuck in your dog’s skin, but there shouldn’t be any significant, enduring effects.

However, others can have both kinds of hair, like tussock moth caterpillars.

Human reactions to these caterpillar hairs depend on individual sensitivity levels.

Allergic responses can lead to bad rashes and extensive swelling.

Fortunately, dogs don’t face the same level of risk regarding possible skin reactions, thanks to the added protection from their coats.

In short, not all hairy caterpillars are poisonous to dogs.

Still, there are some to keep an eye out for.

These are described below.

Which Hairy Caterpillars are Poisonous?

It’s best to learn more about which caterpillars are poisonous and which are not in case your dog gets stung.

Here are some of the most common hairy caterpillars that may pose a health risk to your pup.

Tussock Moth Caterpillars

There are a few different types of tussock moths, some of which can have both hair types discussed above.

Interestingly, even physical contact with their cocoons can produce the same effects as their hairs.

Tussock moths often become a problem when they start dropping from trees or begin searching for a suitable place to spin cocoons.

So, you’ll want to watch where your dog is sniffing around to keep it safe.

Hag Moth Caterpillar (AKA, Monkey Slug)

These are some of the easiest poisonous caterpillars to identify, thanks to their wacky appearance.

They’re light to dark brown in color, with nine or fewer pairs of spines along their sides.

These caterpillars’ hairs may have poisonous glands at the base that release the toxin once the hair has pierced the skin.

Unfortunately, expert views conflict on whether this caterpillar stings or not.

With that said, it’s best to take caution and treat them as hazardous to pets and humans.

Saddleback Caterpillar

The saddleback caterpillar is another type that’s easy to spot.

They appear to be wearing a saddle, given the bright green patch of skin that looks to be draped over the middle of the body.

Their hairs are hollow and break off quite easily.

Each hair will dig deep into the skin, ultimately causing rashes, welts, itching, and inflammation.

Spiny Oak Slug Caterpillar

This is one of the thirty unique species of slug caterpillars in the eastern United States.

It has three pairs of spines on its front end with two more pairs on the back end.

You’ll also see a few additional groups of spines running along its sides.

Spiny oak slug caterpillars‘ hairs break off and will release poison into the skin once the tip of the spine breaks.

Buck Moth Caterpillar

Buck moths get their name from their peak activity period: deer season (a male deer is often referred to as a “buck”).

These caterpillars are best known for painful stings due to the spines located on the front and sides of the body.

Keep an eye out for a black, spiny caterpillar, potentially with white spots, to steer clear.


Not all caterpillars are poisonous to dogs.

The main ones to be wary of are hairy caterpillars, as their hairs can release harmful substances into the body, resulting in various symptoms, from itching to tongue necrosis.

If you suspect your dog was stung by a caterpillar, it’s best to seek a veterinarian’s help as soon as possible.

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National Canine Research Association of America