Prepare to Be Completely Grossed Out: Ever Heard of Cuterebra? (Gag!)

Surprised cat Late summer, early fall… Time for garden mums, harvest moons,  peaches and an X-file maggot poking its head out of the side of your little dog or cat. That’s right, folks, it’s Cuterebra time.

Never heard of a Cuterebra? You’re not alone. These botflies are not that common, but when a pet owner finds one, they don’t forget it.

I usually remove five or six of these gross little critters from dogs, cats or rabbits each year. This past week, we had three of these big maggot-like gross-outs.


Even though they are not that common, if you live in a rural or semi-rural area, it’s good to know what they are so you don’t freak out if you find one poking its head out of your pet.

About the Cuterebra… Not Cute

Cuterebra flyThe Cuterebra fly is a large, non-biting, fat fly that lays its eggs near rodent or rabbit burrows on grass, rocks and vegetation.

Your cat or dog passes by the area, maybe sniffing out a little mouse, and picks up the eggs on her coat. The eggs hatch into larvae and invade the dog or cat through the mouth, nasal passages, or an external wound.

Then, for their next Grimm trick, these creepy little larvae travel under the skin of your pet and set up house somewhere on the head, neck or body. The creeps grow inside their little houses, creating round swellings,  little larvae bungalows — sometimes called warbles. (Here’s a gross photo of them.)

Cutebrebra pulled from a young kitten

This Cuterebra was pulled from a very young kitten. Yuck.

Now, for their Twilight Zone trick, each one makes a little breathing hole, like a chimney, in the middle of the swelling. This is when, while you’re petting Sargent Tibbs on the couch, you might run your hand across this peculiar bulge, look down, and actually see Larva-Man poking its ugly little head out of the chimney. Egads!!! This gives new meaning to the word GROSS!

Feeling a little sick to your stomach, you run to your medicine cabinet and get your tweezers for a DIY surgery, right? WRONG. Although icky and disgusting, this is not an emergency. Mr. Thing has actually been squirming around inside Mr. Tibbs for about a month by now. He became obvious to you only now because he has to come up and out for a breath of fresh air. Seriously! Save the tweezers for your eyebrows — call the vet.

It’s important to remove the Cuterebra in one piece. If you break the ugly little critter into pieces inside his little happy house, you can create a large inflammatory reaction in your pet. Take-home message: The pet goes to the vet, gets the Cuterebra removed, the wound treated, and healing is usually uneventful.

I was awakened the other evening by a very calm dog owner. “There’s a maggot in a hole on my terrier, and I can see its head going in and out.”

I was so impressed with this woman’s presence of mind! I explained to her what it was, that it was not an emergency, and asked if she could wait a few hours until my office opened in the morning. I had some limited hours on Labor Day weekend. She was very grateful not to have to go to the emergency hospital. We saw Scully in the morning, removed Cathy Cuterebra from her hut, squished Cathy to death, and everyone, especially Agent Scully, had a happy holiday.

Preventing Alien Invasions

So, late summer is the time we see most Cuterebras, after the flies have laid their eggs, invaded your pet, and had time to grow and come up for air. How to prevent these infestations?

For rural dogs and cats, there’s no perfect solution if they lie outside near wild rabbits or rodents. Leash-walking dogs and keeping cats indoors is, of course, great prevention. Knowing what a Cuterebra is and what it looks like can reduce the shock factor if you see something like this on your pet.

My introduction to Cuterebra removal was many years ago. A pet turtle came in one summer with 20 of these larvae popping out of arms and legs and neck. First I had to carefully catch the turtle’s arm or leg before he retracted them. Then, carefully remove these larvae. Mr. Turtle was very angry and trying to bite me, even though I was explaining to him that hosting 20 slimy guests was not cool!

The owner had let the turtle bask in the sun earlier that summer. This is not a bad idea, but the turtle happened to be basking on a bunch of Cuterebra eggs.

I’ve seen many pet bunnies with this parasite because rabbits are a preferred host. These bunnies are usually allowed to play and exercise on grass. Bunnies in hutches should not be prone to Cuterebra.

This Is the Gross-Out Section of the Movie

Cuterebra removed from a cat

Cuterebra treatement: Alien invasion, indeed.

Cuterebra are usually one single critter, rating about a five out of 10 on the gross-out scale.

Whenever I’m ready to remove a Cuterebra, I usually call in the new employees so they can have a look. “Yuck. Wow! How cool!” is a typical response.

But even hard-core veterinary professionals don’t enjoy maggots. Here’s a typical, late summer scenario: A sick 12-year-old collie comes in after a week of 95-degree weather with diarrhea. What else do you think might be hiding under the matted, stinking tail? You guessed it. A maggot-fest.

Where did all my technicians go? They’re suddenly all on break? Well, they better eat now. They won’t have an appetite later.

Owners, if this ever happens to you, don’t be embarrassed. But you need to get to your vet. Let me point out some risk factors so maggot infestations can be avoided.


  • Occur in thick-coated breeds most often. Poorly groomed collies and shelties are the primary example. (But they can occur in any dog breed or cat.)
  • Occur in hot weather, because of fly strike.
  • Occur more commonly in older, recumbent animals who don’t groom or stay in one, outdoor place for a long time.
  • Occur if the animal already has a wound, or is soiled around the rectal/vaginal area.

These pets can become very sick from the associated infection caused by maggots (myiasis).

Get your pet to the vet if you even suspect maggots so the animal can be examined and the entire area can be professionally clipped, de-maggotized, surgically cleaned and medicated. I have had several debilitated animals running temps as high as 106 because of maggots. These guys may need IV fluids and IV antibiotics to be stabilized. If the animal was sick or debilitated before the maggot problem, the combination of  illness and parasites can be fatal.

I took a quick poll, and most vets and techs don’t think there are too many grosser things out there than creepy crawlies. I usually work these cases myself because I don’t want anybody else fainting.

As is our mantra in the veterinary profession, don’t just “wait a few more days,” particularly if you see a swelling, an area of matted fur or a wound of unknown origin. Don’t let your pet become Lord of the Flies!

Photos (from top to bottom): niseag03/Flickr, dsuzoology, fallsvetclinic/Flickr and Tiger Girl/Flickr

book-cover-smallest1Have you ever had this pest removed from your pet? Tell us about it in the comments below. If you enjoyed this article, you’ll love Pets Adviser’s email newsletter. It’s free to sign up, and you’ll be among the first to get alerts about major pet food recalls. New subscribers also get instant access to our 40-page ebook — which has “secrets every cat and dog lover should know.” Learn more here.

From Around the Web

  • pet rus

    Oh my goodness those maggots are disgusting,ai my poor cat…. does that happen to all the cats? Ai my poor cat…i mean… i do groom him everyday and dont find anything…but he spends most of his time outside in the garden. Oh man… Thanks for this info.

  • kali

    So I thought it was an infection so I kept squeezing for puss to come out but a larva just popped out, I think it was whole but I don’t know what these things look like. I’m worried.

  • Shirley

    You are wonderful! Thank you for such gross information…given in a more palatable way. Wish you could be our vet….

  • Ann

    Ugh! I rehab critters and it looks like I have my first case of this nasty little parasite in one of my rescue babies. I sent a picture to my wild baby vet and she said it looked like a cuterebra. Of course I had to look it up and see what it was and you are quite right. Yuck!
    Thank you for that education. It was very helpful. Now I know what to expect at the vet and won’t be in for a nasty surprise.

    • ann

      I found a links point kitten that I think was dumped out because she was lethargic and the breeder knew she had a problem. I had her two days and noticed a lump on her neck, got to looking further and seen the nasty worm, my husband pulled out the thing, the kitten and myself ran!! That was so sick, I got sick too. That following Monday I took her to the vet and she is a whole lot better now after the cleansing and some amoxicillin. Prayers to anyone and any pet that has to go through that.

  • Sharp

    I noticed the warbles a few days ago and thought they were ant bites. I am in Ghana. Then I saw the maggots today. Terrible! I called my vet, who calmed me a little with her explanation, but still… very disquieting. Maggots on a live animal?

  • Angel

    My mothers cat has a round like swelling under her armpit that has continued to grow. It now feels like a cyst of some sorts. Nothing has broken through the sking though and when you squeeze it it just kinda feels hard. Could this be a warble?

    • maddy

      Yes it could. Sometimes it is so hard to see the hole, depending on the warble.

  • Jonathan M.

    I actually removed one from a young kitten just a little while ago. The kitten was, at birth, feral. But once it became sick and needed food, it tamed to my son and I eventually got it’s trust. I saw two wounds, from entering and exiting the metal vents leading under our brick (The metal was scratching it’s neck each time it would enter or exit). One wound was just a wound…no critters, just a little infection. The second was under the neck and I didn’t see it at first. Then today I noticed the perfectly round hole, and thought it looked odd when I poured peroxide on it. This evening I decided to check it a bit closer, and pressing it caused the larvae to poke out hemostat in hand, I pressed, grabbed and removed it. The kitten seemed delighted. Treated with peroxide and now it’s healing, I hope.

    • David Deleon Baker

      That must have been… horrible. Here’s hoping you or your kitten never have to go through that again!

      • Jonathan M.

        Checked on it last night and yesterday morning…and it looks like it’s healing well. Triple antibiotic ointment being applied liberally..seems to be nearly closed up completely.

        • David Deleon Baker

          Glad to hear it.

  • Angie

    I just had to non-pleasure of dealing with this nasty thing. Someone dropped off a kitten outside my home 2 weeks ago and she fell in love with my family. After a week of fighting with myself to NOT keep another cat. We allowed her into our home and hearts. She is 8 weeks old and full of life and very playful. All of a sudden she became VERY ill. I couldn’t figure out what was wrong and seriously thought she was going to die in my arms before the vet’s office opened in the morning. After getting her to the vet with a very high fever and dehydration from not eating or drinking I was told that she had one of these gross things on her neck and the severe sickness was being caused by an allergic reaction to it. So they got her fever under control and removed the bug and now she is very sore but on the mend. I have never heard of anything like this before but I have 2 dogs and now 2 cats and am going to be more aware of these little buggers in the future..

  • Carole

    Do I HAve To Worry About My Other Dogs And Cats When Around My Infested Dog Until I Get To A Vet?

    • maddy

      No, they can’t be infected by the larvae already in the one pet.

  • the garden sherpa

    I removed one each of these lovelies from each of my patterdale terriers just this weekend, nasty business. Each time I noticed what looked like a thorn hole or splinter, they catch thorns a lot, I put on a medicated gel on area and each time the area swelled larger, allowing for a good push and out comes a freaking maggot. LOVELY.

    • alyssa

      What did you do after to keep the wound from infecting more ? Will it jjst deflate in time?

  • Erbaciousk

    Just discovered and had one removed from my cat’s abdomen this afternoon. About 2 centimeters long. The air hole was pretty large by the time I found it; I thought it was part of his intestine coming out of a wound at first. The vet’s assistants and I were pretty grossed out, but the vet was very excited. She made a video of the extraction, and didn’t charge me for the visit.

    • Pets Adviser

      Glad it’s out of your cat! Sounds gross. Your vet probably doesn’t see THAT every day.

  • Sissy

    I have a pup that has this too…She is just 6 months old. She is not outside very much but when I had her out one day on a leash she found some old poop left from another dog. Could she have ingested some of this by smelling or licking. Maybe the eggs were on it. I had her at the vet yesterday and they removed one and taking her back today to remove the other two. Does she have a chance to have more come up or will all of the larva be at the same stage and are all moving up to break through the skin? I so want it all to be over today…Thank you so very much…

  • Blake

    We used to get them a lot with our kittens on the farm. If the hole is clean and the grub is still alive, just spray it with a tiny bit of starting fluid (ether) and it will come out where you can grab it with tweezers. Usually the holes don’t get infected unless the grub dies in there.

  • Jaime

    My dog has a hard lump right above her tail and when I discovered it today I squeezed and out came some puss but now there’s nothing coming out but it’s still fairly hard. Could this be a warble?