The Incredible Journey of My Dog’s Butt Worm

Meet Lucy Bea Rice, the exquisite mutt with an infamous worm. Photo credit: Eleanor Spicer Rice.

It was shaping up to be a fantastic day. A little before 6 a.m., I was taking a walk with the light of my life, Miss Lucy Bea Rice, an exquisite mutt who looks like the product of a love affair between a large rabbit and a fluffy sheep. Lucy Bea spent the earlier part of our morning ramble snarfling up all the pizza crusts charitable college students tossed into the bushes the night before—both her hobby and her civic duty—while I enjoyed the pinks and oranges of the sun doing its morning push-up.

The real excitement began just after what I consider to be her favorite part of the walk, her pooping. All-in-all, nothing seemed out of the ordinary. Somehow, she even makes pooping seem like an endearing gift she’s bestowed unto the world. Nothing, that is, until I bent down to pick it up. There, on the top of her poo pile, was a white, pearlescent stripe, flat like a linguini noodle and about a quarter of an inch long. And it seemed to be … hold on … let me poke it with a twig … yep. It was moving.

I snatched up her deposit in a plastic bag and hurried over to her vet/my neighbor’s house.

Here’s an etiquette tip I learned from this experience: No matter what your neighbor’s profession is or how sparklingly adorable your dog is, no person in this world appreciates your showing up at his house at 6:30 in the morning with a bag of feces you brought just for him. Nobody. Learn from my mistakes.

He didn’t need to look at the BM bag, he told me. He knew exactly what was burrowing through Lucy Bea’s bowels.  My perfect pooch, my magnificent mutt, was hosting a butt party for a flatworm known as Dipylidium caninum, the flea tapeworm.

What he told me next nearly made me open the poo sack to see for myself.

The piece of wiggle I saw in her poop wasn’t actually the tapeworm, he told me, not what we think of as the tapeworm, anyway. It was a piece of the worm filled with eggs. The rest of the worm remained hooked head-first in her intestine, feeding away on nutrients meant for my beautiful Boo Boo Bear.

Flea tapeworms look like a flattened string of pearls, only they’re smaller toward the head and bigger toward the tail. They grow from the head on down. Each “bead” on this string is a developing segment with male and female organs and the capacity for egg-making. The closer to the tail, the more mature the segment. At the worm’s posterior, egg packets, mature segments stuffed with fertilized eggs, break off and take the ride of their lives on the poo train.

Left: Dipylidium caninum egg packet, containing 8 visible eggs, in a wet mount. Right: Adult tapeworm of D. caninum. Credit: DPDx CDC.gov

Once outside, the egg packet disintegrates, and the eggs are strewn on the ground, rip roarin’ and ready to go. They hang out and wait for flea larvae to come eat them. (Here I should point out that while adult fleas are undeniably gross, baby fleas look like happy, fuzzy worms, bumbling around the ground picking up detritus and, in some cases, tapeworm eggs.) When a flea larvae feasts on a tapeworm egg, those poor baby fleas get worked over just like Lucy Bea did. Little tapeworms burst into the flea’s intestinal wall, latch on, and develop there in that tiny flea-sized body cavity into the flea’s adulthood.

Worms rely on the fact that adult fleas do what adult fleas will do—squeedle around on animals annoying them. Worms also rely on the fact that annoyed animals do what annoyed animals will do—gnaw around in their fur until they catch the fleas. When that happens, when Lucy Bea gnawed around and caught the infected flea, she killed the flea but introduced a delighted tapeworm to the joys of her digestive system.

If baby fleas didn’t grub around on baby worms, adult worms couldn’t find a way into Lucy Bea’s pristine digestive system (unless I had a poo eater in my midst, and I don’t). Tapeworms need that intermediate host to complete their sojourn.

Considering all that worm had been through, I nearly felt bad giving Lucy Bea the tapeworm killer pill. A commendable journey, Mr. Mrs. Tapeworm. I will miss you in the a.m. poop.