Friday, July 30, 2010

Let's see if I can gross you out

[If you have a sensitive stomach,
you might want to skip today's post.]

A client brought in a new-found kitten today with a sore on its neck. I was excited before I even saw the patient, because a sore on the neck of a kitten in summer usually means one
of my favorite summer time conditions: Cuterebra!

But, I am getting ahead of myself. Let's go back to the beginning and that moist, icky sore on the neck of an 8 week old kitten.

Is it an abscess? A bite wound? No, it's not.

Look closely at the hole. See the little white thing sticking out, with a dark ring in the center?Here, I'll point it out to you.
A close-up (Forgive the fuzzy focus - I was using the little point and shoot belonging to the office, not my Canon Rebel.)
What could it be?

It is a spiracle, the breathing apparatus of a warble, the larval form of the Cuterebra fly, which is a member of the botfly family. Similar botflies include the ox warble that causes "grubby back" in cattle, the stomach bot in horses, and the nasal bot of sheep.

Cuterebra primarily infest rabbits, although cats, and occasionally dogs, may be victims. The female fly lays its eggs on plants along paths frequented by rabbits. When the rabbit passes by, the eggs hatch instantly and the larvae crawl onto the host's fur. They enter the body through natural openings, (nose, mouth, anus, etc.) and migrate under the skin. They usually end up in the neck area, although I have found them on other body parts.

The larva cuts a breathing port through the host's skin and attaches its spiracles. These respiratory openings, it should be noted, are at the butt end of the grub, not the head end like you might expect. Not pertinent to treatment, just a fun factoid I like to share.

The developing organism sets up a strong inflammatory reaction in the rabbit or cat, leading to moist, painful wounds like we see here. A warble wound may resemble a standard cat bite abscess but for one thing: if you observe the opening carefully, you can see the movement of the larva at the breathing port.

That's where I come in. Rather than allowing the warble to finish its life cycle, enlarge its breathing port and drop to the ground to complete its metamorphosis to an adult fly, I swoop in to remove the little bugger. Just a small nick to enlarge the hole, and I can grasp the butt of the warble and slowly, carefully extract it.

(Please excuse the Band-Aid. A slip with a dental elevator earlier in the day gouged my thumb.)

TA-DAH! Victory!

Here's an even better shot, complete with a centimeter ruler for scale.

Astute readers will note that the warble itself sustained an injury during the extraction process. This is the first warble I have ruptured during removal, and luckily, it happened after that part of the larva was out of the kitten's body. If a warble is ruptured under the skin, it could set up an anaphylactoid reaction that might prove fatal. For that reason, warbles should not be casually squeezed out of the hole, but removed delicately.

After the minor surgery, we cleaned up the kitty's neck and gave her an antibiotic injection. The wound is not sutured, but allowed to close on its own. Once healed, in 7 to 10 days, she'll be as good as new.

Update, Aug. 2:

Three days after warble removal, look how much better the wound looks.
Even the kitty is happy about the outcome.


Susan Gets Native said...

That was freaking AWESOME!!!!

Heron said...

Just as Susan said, that is a really cool post ! I'm glad the kitten found her way to you and hope she lives happily ever after. Sara

Mary said...

Aaack! Thank you, Kathi! Thank you for everything you do...

retriever farm said...

poor little bot fly, he just wanted to reproduce.

Elizabeth said...

That is extremely gross and fascinating. I can't believe it's so big!

Heron said...

So, now I'm curious, do some bot fly species lay eggs in the skin of the host with the eruption occurring at that site ? Or do all have the circuitous method of entry and migration through the body ? Thanks !

Kathi said...

Sara: The life cycles of the different botflies all vary a little. The adult fly that causes stomach bot in horses lay their eggs on the horse's legs. The horse licks its legs and ingests the eggs. The larvae stay in the horse's stomach up to one year (but, only 1/2 of the stomach - very peculiar!) until they reach the pupal stage, then are passed out in the feces.

The nasal botfly of sheep lay their eggs in the sheep's nose; the larvae migrate to the frontal sinuses and stay there for about 3 weeks before crawling back out the nose to pupate on the ground.

Hypoderma, the botfly of cattle, lay their eggs on the cow's legs. The larvae penetrate the skin directly, then migrate under the skin till they reach the cow's back.

And, really, isn't this much, MUCH more than you ever wanted to know?

Julie Zickefoose said...

No, it's never ever enough. Please keep trying to gross us out. I'm amazed at the size of the wound on that poor cat, yucccch! And you don't suture it? Wow. Will the hair grow back and everything?

Bowing and scraping to your warbly majesty,

Chimp # 2

denapple said...

Well, do you live an exciting life or what? How drab existence is for the rest of us! :) By the way, how is Panda doing?

Heron said...

Kathi: Thanks for answering my questions and I totally agree with Julie, it is always fascinating to learn more natural history and scientific factoids...from both Science Chimps !
Now, I'm off to re-check all those sebaceous cysts and extraneous bumps on my aging dog ! :0

Kathi said...

JZ: Yup, abscesses and other contaminated wounds should never be sutured, as you just trap all that cruddy infection and stuff under the skin, only for it to bust out some place else later on. The wound will close with barely a scar, and the hair should all come back. Most of the hair loss was just where the moist drainage was collecting, so the underlying follicles weren't damaged.
I'll try to get follow up pics on Monday when I see the kitty again.

Anonymous said...

So, I take it you weren't bored, with nothing to do all day, after all? Seriously gross pics, but fascinating at the same time. Years of working around med students have toughen my sensibilities (it's only a picture, for crying out loud), but if I were there in real life I'd be crying or barfing, maybe both - and no use to the poor little kitten at all. Vets are awesome.

littleorangeguy said...

Oh. My. God. I can't believe I read the whole thing. I thought toad eggs were bad ... I feel slightly dizzy now.

My word verification is "subswaxi," which seems shockingly appropriate.

Kelly said...! Amazing. My son wants to be a vet, so I'm calling him in now to take a look.

dguzman said...

Oh my gosh, I was in a restaurant just last week and I heard some people at a nearby table talking about how their kitty had this very same thing! Wild.

What a cute kitty! Nice work, KatDoc!