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Doxycycline and amoxicillin.

Species: Dog
Breed: Pitbull
Age: 6-12 months
My dog is believed to have Lyme disease, her test was negative but our vet thought it might be to soon to show up. She was doing great on doxycycline for a week then went down hill again. Her joints hurt and she cries when getting up from laying down and has had a fever of 104. Our vet kept her on the doxycycline and also put her on amoxicilin. Is it safe for her to be taking both at the same time?


Online vet, Dr. Marie

Dr. Marie replied:

Sorry to hear that your dog is not doing well. It's true that the test for Lyme disease often will not turn up positive until 4-6 weeks after the dog has been exposed to Lyme disease.

Her symptoms certainly sound like lyme disease with sore joints and a fever.

Now, your question is an interesting one. Is it safe to be on doxycycline and amoxicillin at the same time? I had to do some research for you to find out the answer to this and even after doing research I am not completely sure.

Amoxicillin sometimes can treat lyme disease. It is sometimes used in dogs that can't take doxycycline well. (Some dogs can get stomach upset on doxycycline.) But it is not commonly used at the same time as doxycycline.)

There is a form of amoxicillin called clavulanic acid that we know should not be used with doxycycline. But, it is not the amoxicillin part of clavulanic acid that makes it not good to work with doxycycline.

I did find one example of a case where a vet used both doxycycline and amoxicillin at the same time. I would not say that it is commonly done, but it really should be ok. If, however, Dakota is having stomach upset (vomiting and diarrhea) then you may want to ask your vet if one of the antibiotics should be stopped.

I think the whole idea of adding the amoxicillin is because we don't know if this really is lyme disease. Amoxicillin may be effective against other types of infections that the doxycycline may not get.

I hope she is feeling better soon!

Dr. Marie.


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Disclaimer: Although Dr. Marie is a qualified veterinarian, the information found on this site is not meant to replace the advice of your own veterinarian. AskAVetQuestion.com and Dr. Marie do not accept any responsibility for any loss, damage, injury, death, or disease which may arise from reliance on information contained on this site. Do not use information found on this site for diagnosing or treating your pet. Anything you read here is for information only.

Customer reply:

Doing some searching online I came across immune mediated polyarthritis which also fits her symptoms. I know she is young but could this be what it is and why she is not responding to the antibiotics?


Online vet, Dr. Marie

Dr. Marie replied:

I could certainly see immune mediated polyarthritis being a possibility here. It is not very common though. I can think of one dog in 13 years that I have diagnosed with that issue.

If you live in an area that sees a lot of lyme disease, then lyme is much more likely, but it can be hard to prove.

The test for polyarthritis is to do joint taps. This is probably a good idea. But, it can be a little expensive because it is a challenging thing to do, plus you have to send samples to a pathologist to read.

I think it's not a bad idea to give the new antibiotic combo a try. If that's not working after a few days then you could ask your vet about the joint taps.



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Dr. MarieDr. Marie is a veterinarian who practices in a busy animal hospital in Ottawa, Ontario. She created Ask A Vet Question as a resource for good, accurate veterinary advice online. Dr. Marie treats dogs, cats, hamsters, guinea pigs, and rats. She has been a vet since 1999.

Is an online vet visit just as good as a trip to your veterinarian? No! But, many times, asking an online veterinarian a question can help save you money. While Dr. Marie can't officially diagnose your pet or prescribe medications, she can often advise you on whether a vet visit is necessary. You can also ask Dr. Marie for a second opinion on your pet's condition.