Friday, July 30, 2010

The Lyme controversy

This morning at grand rounds, the room was more crowded than I have ever seen it. Every Friday morning, from 8-9 am, a resident or intern presents on a particular topic. People come if they are interested and if they are free. I have seen grand rounds have as few as a dozen people in attendance. There must have been at least fifty today. I have seen rounds where no one asks a question. There were about a dozen questions asked today. The resident closed her talk with a picture of boxing gloves and announced, “This is a controversial topic, so let’s keep our gloves on while we ask questions, okay?” The topic was Lyme disease.

What is Lyme disease?
Lyme disease occurs in humans and dogs, though it presents differently in the two species. (Cats don’t get clinical signs of Lyme.) The disease is caused by a bacteria called Borrelia burgdorferi. The disease is often not serious, with clinical signs like lameness, loss of appetite, and lethargy. These signs are usually resolved after a course of antibiotics, usually doxycycline.

However, Lyme is associated with Lyme nephropathy, a disease of the kidneys which can be fatal. This is a less common outcome, but a very serious one.

Lyme has been studied in laboratory dogs. However, Lyme nephropathy appears to occur most often in Labrador retrievers and golden retrievers; it is possible that they have a genetic predisposition for it. So what we have learned in laboratory dogs (who are almost exclusively Beagles) may or may not apply to retrievers.

Should I vaccinate my dog for Lyme?
This is the first part of the controversy. Different veterinarians have different answers for you.

Some say: Yes! The vaccine is very safe and effective. The possibility of Lyme nephropathy makes any risks associated with vaccination to be well worth taking.

Some say: No! We don’t actually know that Borrelia causes Lyme nephropathy. Some people suspect that it may in fact be associated with the Lyme vaccine. Moreover, 95% of dogs who are exposed to Borrelia never develop any clinical signs. In other words, they never become sick. The few who do develop clinical signs are almost always easily managed with antibiotics. Why take a chance with a vaccine, which may have side effects, when the chances that your dog will develop Lyme nephropathy are so low?

My dog is Lyme positive. Should I treat him with antibiotics?
If your dog shows signs of lameness, fever, lethargy, and has a positive Lyme titer, then definitely he should receive a course of antibiotics. (Of course, a vet will rule out any other likely diagnoses first.)

What if your dog shows no clinical signs? This is the second part of the controversy.

Some say: Yes, the dog should be treated. Otherwise, he is at risk of eventually developing Lyme nephropathy. Best not to risk that.

Some say: No. The likelihood is that the dog will never develop any clinical signs (that he will remain healthy). We don’t actually know, again, that Lyme nephropathy is actually “Lyme” nephropathy. Antibiotics are not 100% safe, and may have side effects. Administration of them may lead to antibiotic resistance. Additionally, most dogs who are treated for Lyme with antibiotics maintain a positive titer for Borrelia after treatment is concluded. In other words, their immune system continues to produce antibodies against the bacteria, suggesting that they still have Borrelia in their systems, despite treatment (though presumably lower levels of it). We may actually be breeding resistant strains of Borrelia in our own dogs by treating unneccessarily. Again, 95% of dogs who have positive Borrelia titers never develop signs of the disease.

It is possible (and probably a good idea) to monitor Lyme-positive dogs by periodically checking their urine for extra protein (“proteinuria”). This is a sign of kidney issues. Even this is up for debate, though, as the test can be expensive and it’s not clear how often it actually catches a problem.

One interesting point made during the discussion at the end of the lecture was from an IDEXX representative. She said that a veterinarian had told her that he routinely treated Lyme-positive dogs, and on re-testing found their Lyme titers to be reduced. A faculty member pointed out in response that as no control group had been tested, it is possible that Lyme-positive dogs see titer reductions after some period of time anyways.

What do I do?
My dog, Jack, tested positive for Lyme this past spring for the first time. There are indeed plenty of ticks in my back yard (though I do my best to manage them with frequent mowing). His positive Lyme titer means that he has “seen” the disease — been bitten by a tick which carries Borrelia. His immune system has responded appropriately, making antibodies to the bacteria. He shows no clinicial signs; his appetite is excellent, and he is no more lethargic than any other aging golden retriever. I had his urine tested; he has normal protein levels. I have not treated him with antibiotics.

I’m reporting what I learned in this morning’s talk from memory. I hope that I did not misreport any facts, but please take all statements with a grain of salt, as I have only completed two years of veterinary school.

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  1. Thanks for this discussion. We just lost our beloved Aussie. She was 8 years old and had LD at 2 - 3 yo. First sign was wandering lameness but that was all. Had high titers and took 6 weeks of doxycycline. Symptoms resolved. About 2 months ago she exhibited a dry hacking cough which looked like kennel cough with some loss of appetite. About two weeks later she started vomiting, wasn't eating her regular dog food (but still taking treats), had poor exercise tolerance, and had mucous/blood tinged - not quite diarrhea stools. We took her to her vet who stated he didn't know what was going on due to the multiple Sxs but said it could be giardia and Rx flagyl. Symptoms improved somewhat over next two weeks with more normal stools. We decided she was just bored with her usual dry food and on 9/7/10 we gave her a new brand and she ate her first whole meal in about the past 2 months and showed more energy than she had showed. On the morning of 9/8 she seemed fine when my wife awoke. I got up bout an hour later and Bikkie did not greet me at all, didn't even lift her head up, something she's never done before. Bikkie stumpled into another room and I took a look at her. Her eyes were rolled back and she was nearly unresponsive. We rushed to the vet. They did labs, xrays, urine, and ultrasound. Found ascites and hypoalbumenia and referred to an emergency vet hospital. She was hypercoagulable, had had a stroke, had a 12cm clot in her distal aorta just above the bifurcation - with weak distal pulses B/L, otherwise hypertensive. ICP was elevated. Treatment was started to control fluid balance, reduce ICP, treat possible bacterial infections (doxy again). Over the next 3 - 5 days she failed to respond to doxy, bun/creatinine continued to get worst and she had more strokes (despite lovenox). She progress to anuria and the aortic clot enlarged to the point of losing distal pulses even by doppler. Lyme's titer in 300s. We were astounded by the rapidity of her decline and have been searching for the cause. Seems right now that lyme's nephropathy is the number one suspect. Vet send her kidney for pathologic study. Sadly, we had to put our much loved little girl to sleep the evening of 9/13/10. Someday, when this pain is gone, I'd like to get another Aussie and will face the decision to vaccinate or not. We live in a high lyme's area with thick woods just behind our property in PA. I've been reading all i can find on the subject and will be following the evolving issue. I find it odd that no vet she ever saw (maybe 10 - 12) ever even discussed vaccination with us. Only other dog lovers know the pain we feel. Perhaps she was one of the unfortunate dogs with a genetic risk of severe renal damage from the bacterial attack or her own immune response. Hope the vet research and clinical worlds keep working on this issue. God Bless and best of luck and good fortune in your studies and profession. Rob and Terry A.

  2. I'm so sorry about your Aussie.

    It is an interesting story -- you did treat her for Lyme, and she still may have developed Lyme nephropathy. So that's one anecdotal point in favor of thinking that antibiotics to reduce Lyme titers may not be helpful in preventing Lyme nephropathy. Hopefully we will figure out that disease's cause some day soon. It's going to be very interesting.

    Good luck with your learning about this issue and with your decisions for your next dog!

  3. As a followup to my 9/17 post - we just got her tests back for infectious diseases and she had a 1:64 positive titer for Rocky Mt Spotted Fever. Have no idea when she was exposed. Was this RMSF on top of lyme's? RMSF alone, or lyme's alone causing the renal failure. After a lot of reading I've learned that you need to be highly suspicous in any dog with tick bites in looking for multiple infections. Rob and Terry A.

  4. I can't believe you didn't treat you beloved dog with antibiotics. Giving her them would not hurt but not giving them to you dog has now cursed her to a shorter life of pain and declining Heath.. Your poor dig can not tell you her pain, but her test SHOWED you she has Lyme. What is wrong with you?

  5. I just rejected a comment on this post because it was not as polite as I would like. As you can tell from the June 3 comment, I allow harsh comments directed at myself. However, the comment in question was directed at another commenter. I'm trying to keep the conversation on this blog polite, so I rejected it.

    Commenter, I can't mail you as you posted anonymously, but if you'd like to repost your comment with different phrasing I would be happy to approve it!