Back to the tale of Lucky, the Oklahoma Beagle with the high white count and the Rimadyl addiction.
I was stumped. I went back to the drawing board. The facts were these:
- I had a young beagle, with apparent severe generalized pain that responded exquisitely to Rimadyl.
- She maintained a high neutrophil count for months despite 4+ rounds of antibiotics.
- Ultrasound, X-Rays were basically normal.
- She still has nose worms.
I decided to look into this nose worm thing. When stumped by parasites, talk to the parasitologists.
Parasitologists are a very interesting species of veterinarian. They dedicate their lives to the study of creepy crawly disgusting creatures. Subsequently, they tend to be a bit odd.
Tom Craig, the venerable parasitology teacher at Texas A&M University College of Veterinary medicine definitely was odd. He used to sing us a song about a sheep parasite. He is rumored to have infected himself with tapeworms just to see what it felt like. Needless to say he knows his parasites.
I decided to give him a call to see if the Eucoleus boehmi parasite was the cause of all of Lucky’s woes.
Dr. Craig said “absolutely not”. The worm was a red herring. He said that based on Lucky’s muscle pain, high white count, and the fact that she’s from Oklahoma made him strongly suspect a parasite called Hepatozoon.
I informed him that I tested for Hepatozoon waaaay back at the beginning of this saga (when Dr. Nitsche laughed at me for thinking it could be that). The test was negative.
He informed me that unless I did the PCR test 7 times, on 7 different days and got 7 negatives then he didn’t put much stock in my test result. He said that the test is very accurate for detecting those little pieces of DNA, but the amount of actual DNA floating around varies immensely from day-to-day. The gold standard test for this disease is a muscle biopsy.
He told me I needed to call Susan Little, DVM, apparently one of the foremost experts on this disease who happened to live in Lucky’s home state of Oklahoma. Dr Little is on faculty at the Oklahoma State College of Veterinary Medicine.
She is the rare “cool” parasitologist. I actually had the pleasure of attending a lecture (well, if you call attending a lecture on parasites a pleasure, maybe it’s a vet med thing) given by her a few weeks ago. She is totally normal, she just love, love, loves ticks and other parasites.
Turns out Oklahoma is a hotbed for ticks and tick borne disease. I had no idea, you should have seen some of the slides she showed, ticks swarming like fire ants. She said she has to check her kids for ticks DAILY!
Anyhow, prior to actually seeing her in person, I spoke with her via phone. She does extensive research on Hepatozoon, and maintains a colony of Beagles that are actively infected with the disease so that she can study them. Turns out that the drug of choice to make these dogs comfortable and happy is Rimadyl (and no, I’m not getting any money or kickbacks from the Rimadyl people, it just happened to be the drug the first vet put her on and it’s a decent drug so I kept her on it).
Dr. Little echoed what Dr. Craig said: this dog sounded like a textbook Hepatozoon case.
I pulled out my trusty Greene’s “Infectious Diseases of Animals”. In my world, the Bible of infectious disease. The article on Hepatozoon was like a play by-play of Lucky’s case:
- Generally causes back pain (usually in the lumbar area)
- Usually dogs have undergone several rounds of antibiotics to treat for fever of unknown origin.
- Waxing and waning signs.
- Back pain often mistaken for diskospondylitis or meningitis.
- Sometimes mistaken for pyometra.
- Most consistent lab finding is an extremely high neutrophil count ranging from 20-200K cells.
For all intents and purposes, it looked like I found my diagnosis. To prove it I needed a muscle biopsy.
I called her owner and relayed what I learned.
She was leaning towards euthanasia. Lucky was young and she had already been through a lot. The owner had been diligently trying not to get attached. If we could cure the disease that was one thing, but if she had to live a truncated life, chronically infected, and that was not an option. They had some personal issues and just euthanized a chronically ill dog a year or so ago.
They asked me to look into her treatment options.
Back to the books: turns out that there is no cure for Hepatozoon. (In case you starg Googling, Hepatozoon americanum is the strain I’m talking about. Hepatozoon canis is generally a mild self-limiting disease). The organisms form thousands of little cysts inside the dogs muscles and you can’t get rid of them.
To control the disease you give an initial round of:
Ponazuril (a drug used to treat protozoal infections in horses, I think I knew about it in vet school)
Or “Triple Therapy”, a combo of Trimethoprim Sulfa, Pyrimethamine (another large animal drug I had to look up), and Clindamycin.
This treatment is supposed to basically put the clinical signs of the disease into remission. However, this only lasts about two months or so. In order to keep the pets in remission, you have to give a drug called Decoquinate for the rest of the dog’s life. You can never get rid of the tissue stage of the disease.
Decoquinate (pronounced de-cock-quin-ate) is a sheep anti protozoal. I had to do a lot of searching to find this stuff. There are not many sheep in the Plano, Texas area (we’re pretty urban, contrary to popular Texas stereotype) so the feed stores around here do not carry this. On the internet I found it in 50 pound bags for around $500. Lucky needed maybe a half a teaspoon twice daily.
I reported this to the owner. We had a long talk. She decided to euthanize Lucky. A lifetime of muscle cysts that were constantly straining her immune system and would ultimately shorten her life was not what this client could contend with. At this juncture, she needed a healthy dog. I couldn’t argue with her.
Despite the fact that Lucky was happy and wagging her tail and playing, it was smoke and mirrors. She was really sick.
She died in my technician Kim’s arms. We sedated her first to make it easier on her (and us).
Despite the fact that I was thrilled at the discovery of a rare and unusual disease, it was a hollow victory.
The voice was speaking again though. I never got the biopsy. What if I was wrong and I just condemned this dog to death mistakenly? Another voice said that the client had already spent a ton of money and the dog was still sick, ultimately she would have been euthanized regardless.
I ignored the second voice, I needed to know. I took a muscle biopsy.
I sent it to Dr. Little at OSU.
About a month later she gave me a call: classic Hepatozoon. The doc who looked at the samples took photographs to show the students.
I passed the info along to the client, for what it was worth.
This was such a bittersweet moment for me. I love, love, love diagnosing rare and unusual diseases. I live for the zebra cases (if you hear hoof beats, think horse not zebra, a well-known tenant in medicine: look for the obvious diagnosis, not the obscure disease). But in the end, like in any good dog story, the dog died.
I can’t tell you how grateful I am to her and her owners though for the volume of knowledge that I gained from this case. I can’t think of one in recent memory where I’ve learned more.
That’s got to count for something.