Lyme Disease – A Tale of Two Dogs in Northwest Pennsylvania

By January 13, 2015Uncategorized

1 in 4 dogs tested at Clarion Animal Hospital in the year of 2015 were positive for Lyme disease!   Our veterinary clinic is in Pennsylvania, one of the states with a high rate of Lyme disease. Here’s a great interactive map of how common Lyme disease is in the USA by the Companion Animal Parasite Council.

At our clinic we use a “snap” test to screen dogs for Lyme disease. Dogs are screened as part of the annual wellness exam or, sometimes, because we suspect Lyme disease.   To shed some light on this confusing subject of the Lyme positive result, I’ll describe two different dogs. Both of the dogs were subjected to the same test, both had the same test result, but both are two very different scenarios.

Norman, a German Shorthair Pointer (the names and breeds have been changed to protect the innocent), is a hunting dog and a family pet.  He came in to our clinic for his annual exam.  He is the picture of health!   Abby, a Beagle, stays mainly inside but is known to chase the occasional rabbit.   She came in for a painful limp that developed in both her front legs.

Both Abby and Norm tested positive for Lyme.

A positive for Lyme on the snap test tells us two things – the dogs had a tick on them (the Deer Tick, see our blog “tick tock it’s deer tick time”) and that the tick was carrying the Lyme organism Borrelia burgdorferi, a spirochete bacterium.  More specifically it tells us that Norm and Abby are seropositive for Lyme, which means they made antibodies to the organism (but, unfortunately, not the same protective antibodies that vaccination affords).  What does the test NOT tell us?  The test doesn’t predict illness, doesn’t tell us WHEN they were infected, and doesn’t tell us if their body is winning the war against Lyme.

First we’ll talk about Norm.  Yes, Norm’s owner remembers pulling a few ticks off his dog last fall.  No, he never remembers Norm limping.  Norm races across the fields after pheasant, chases frisbees – his owner would definitely know if he had been limping.  The timing fits – it takes 2 to 3 weeks to be able to detect the antibody after exposure.  The lack of symptoms also fits – some studies say that 95% of dogs exposed to the Lyme organism will never show any symptoms.  So does Norm go home on antibiotics?  Probably not, we’ll just have the owners watch for symptoms of limping.  However a serious, but rare, complication of the Lyme organism is kidney disease, so we will routinely check his urine for protein.  If his urine tests positive for protein we’ll err on the side of caution and send him home on antibiotics.  If not –we’ll have Norm’s owners continue to monitor closely for any limping and continue to monitor the urine for protein.  We’ll tell Norm’s owner that it may take 2 to 5 months to show limping in dogs after exposure to the Lyme bacteria (unlike people with Lyme disease that seem to get sick right away after the tick bite). He might not be out of the woods yet!  And we’ll tell Norm’s owner that dogs are sentinels for human exposure to the deer tick.  Most likely where Norm goes his owner goes, so they also may have been exposed to Lyme disease and should be vigilant about checking for ticks on themselves.  Oh yes, and we’ll recommend tick control (year round!) and also a Lyme vaccine if Norm is not already vaccinated.

Next let’s talk about Abby.  She’s not only limping but she has a fever.  She hasn’t been eating well for the last few days and her owner is really worried about her.  On exam, her front legs are very painful at the “wrist” joint. Abby’s owner doesn’t remember finding a tick on the dog, but does know that her neighbor had Lyme disease and was really sick from it.  Abby is showing the classic signs of Lyme disease in dogs.  She’ll be treated with antibiotics for 3 to 4 weeks and will be feeling better in a few days.  We’ll put her on doxycycline (it’s good for other tick-borne diseases also) but if the antibiotic upsets her stomach, amoxicillin will work for Lyme disease.  She’ll probably get pain medicine for her joints.  We’ll also check Abby for protein in her urine (luckily only 2% of symptomatic Lyme positive dogs will go on to develop kidney failure).  Finally, we’ll counsel Abby’s owner on good tick control and suggest a Lyme vaccine when she’s feeling better.

Both Norm and Abby will most likely continue to test “positive for Lyme” on their next snap test for at least a year but we won’t know for sure if it’s lingering antibodies from this year’s infection or if it’s a new infection.  We know the ticks are out there, so it might be best to assume it’s a new infection.  A test that quantifies the antibody titer can be used to help determine if it is a new infection or an old infection.

At Clarion Animal Hospital, we follow the guidelines presented by the American College of Veterinary Internal Medicine (ACVIM) (see the article “ACVIM Small Animal Consensus Statement on Lyme disease in Dogs: Diagnosis, Treatment, and Prevention”)

To summarize, if your dog:

  • tests positive for Lyme and IS NOT showing symptoms and IS NOT positive for protein in the urine – no treatment
  • If your dog tests positive for Lyme and IS NOT showing symptoms but IS positive for protein in the urine –  treatment for Lyme disease with an antibiotic for 3 to 4 weeks while other causes for protein in the urine are looked for and treated; also a baseline Lyme C6 antibody test.  We just don’t know if the Lyme positive is incidental or a marker for the organism causing the kidney disease.
  • If your dog tests positive for Lyme and IS showing symptoms of Lyme disease (fever, loss of appetite, and limping) – treatment with antibiotics for 3 to 4 weeks while other causes for the symptoms are evaluated.

A further review of the Lyme-positive dogs mentioned in the beginning of this article showed that of the Lyme positive dogs at Clarion Animal Hospital, one-third of these were limping!  These Lyme positive, limping dogs were… LYMPING!!!!  If you suspect your dog of “lymping” or you are concerned about tick exposure and want to know more about tick control and how to prevent Lyme disease contact your veterinarian to have your dog evaluated today.