KIDNEY WORM
- 7 hours ago
- 5 min read
Tavishi
The RVC library is my dream. As someone interested in a fairly niche area of biology, I've grown accustomed to finding online versions of textbooks because they're either, a, 300+ dollars, or b, not available in any libraries near me. The RVC library, though, has every textbook I could possibly want.
Not only do they have my favorite general biology textbooks (Vander's, Albert's, Lehninger's, etc.), but they have all the highly specific veterinary textbooks I'm interested in. For example, The CRC Handbook to Marine Mammal Medicine and like an entire freaking shelf of Miller's Anatomy of The Dog and every possible edition.
Every now and then, the library does a mass book sale where they sell a bunch of textbooks for less than 5 pound. I got a copy of Veterinary Parasitology for only 2 POUNDS. It was incredible, and made my day/week/month/year. They were selling this particular book for so cheap because it was third edition, and we'd recently gotten a shipment of a bunch of fourth editions.
I don't mind an older edition, though.
Anyways, something something parasitology, something something helminths!!! Parasitic worms are BAD for you and bad for animals. Thus concludes my post.
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Just kidding, y'all are delusional if you think you can get me to shut up so quickly. I, in theory, started this blog because I'm passionate about science education. In reality, I'm just a D1 yapper.
Anyways, I also recently struggled through the absolute hell that was our week of renal physiology. I'm a kidney hater. I generally like worms except when they're being gigantic menaces (double entendre that you will understand very, very shortly)
I'm not such a kidney hater that I would want kidney parasites, though. Dioctophyme renale, or the giant kidney worm, is the largest parasite infecting mammals. (Now you should understand the double entendre.) Male worms tend to be significantly shorter than females, reaching only about 40 cm long, whereas female worms can reach 100+ cm long! For reference, I am only 156 cm long (really exposing myself here...)
D. renale infects minks most commonly, but in veterinary practice, the most common patient are dogs. The parasite is transmitted to the definitive host (a host where the parasite reproduces and reaches sexual maturity) through ingestion of larvae, generally via the consumption of fish or frogs.
Sidebar 1: host types
There are a few different types of hosts in parasites.
Paratenic hosts, which really just transport larvae to their final destination without development of the parasite
Intermediate hosts, which allow for immature development of parasites
Incidental hosts, which aren't the target of the worm, and don't transmit the infection further
Definitive hosts, which is where parasites develop and sexually reproduce
Anyways, definitive hosts for D. renale are mostly canids. Humans can be incidental hosts, but fish, annelids, and frogs are paratenic hosts. When humans get giant kidney worm (the common name for this parasite), it's generally a result of eating raw fish.
D. renale colonizes the kidneys of their hosts, and produce larvae which are passed in the urine, hence how the infection is transmitted further. These larvae are generally grown in aquatic environments, which is how they get into freshwater critters. Fish and frogs are paratenic hosts, and annelids are intermediate hosts.
Also, in Canada. Lots of D. renale in Ontario.
Anyways, worms are dormant and asymptomatic (prepatent) for a while before they start pulling some bullshit. In some cases, worms have been reported to lay dormant for months to even years. Also, it's very rare for kidney worms to show symptoms until very late in infection, which really does not make the job of diagnosis any easier. As is the case with most veterinary parasite diagnostics, infection is given away by either symptoms of literal death or larvae present in waste products.
sidebar 2: diagnostic processes in vet med never fail to amuse me. Because animals can't talk unless they're a kandra I guess (is my dog TenSoon? Remains to be seen), you have to look for very specific symptoms of pain or just go off appetite. Watching the vet I interned at perform exams was so fascinating. I shit you not, when my dog injured her back, she went and palpated her back, and told me to tell her when my dog licked her lips. Goofy diagnostic process, but a tried and tested one. Legitimate science here, folks.
The reason D. renale is called a kidney worm is because they colonize the kidney when mature. This is why their larvae are found in the urine.
Infection is localized to the renal parenchyma, which they destroy until the kidney is just a husk filled with pus and worms.
But also, knowing that the kidney actually does stuff (makes urine), you start to wonder, wouldn't the dog be affected, like, a lot more than symptoms only at death?
Well. The magic of kidneys is that we have two of them. D. renale generally only infects one kidney, and usually the right kidney. This means that the animal is able to keep producing urine, but it's not ideal to push all the workload onto only one kidney. When the infection affects both the left and right kidney, renale failure generally results. Otherwise, symptoms are limited to some dysuria and hematuria.
Also, even though D. renale is commonly known as the giant kidney worm (emphasis on the kidney), it's really bad at making its way to the kidney in dogs. Most cases of kidney worm in dogs just end up with the worm sleuthing around in the gut, with a little bit of preference towards the liver. I do not know why this is the case, but would like to know if anyone has any insight.
Anyways, back to what this worm does in the kidney. The worm slowly feeds off and leeches off (incredible word choice) the kidney until it has nothing but worm enclosed in capsule, leaving behind some incredible suppurative pyelitis (pyelitis means inflammation of kidney, specifically the pelvis, and suppurative means pus is added in). The worms cause issues with urine production, and hemorrhaging of tissue, often blocking ureters and affecting urine production as well as causing nephrotic necrosis.
sidebar 3: i love alliteration. nephrotic necrosis. produced pus pyelitis. hemorrhaging Henle hematuria. damn dysuria.
The general treatment of D. renale is surgical intervention; either taking the whole kidney out, or rooting around in the peritoneum and pulling out whatever worms are found. Pharmacological treatment of D. renale is uncommon, with ivermectin showing some promise (God bless IVERMECTIN!)
Once the worms are adults, you just need them out. Generally, less intervention if possible is the goal, but if it's the only solution available at the time, cutting them out is much preferred to death.
Ok, this concludes the post for this week. I hope y'all have been enjoying the sidebars lately! I've been getting a little bit more creative with the formatting of posts. It's been a busy week, but I will be trying to post again soon!
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