Lyme Disease, Doxycycline and Very High Liver Enzymes (ALT)

We're sorry you're dealing with this right after adopting him, Michelle. Both of your vets may be partly right. Elevated liver enzymes are a recognized side effect of doxycycline, the usual antibiotic for Lyme disease, and they are more common in dogs than in cats. But an ALT over 700 is a significant rise, and other causes should be ruled out.

Questions worth asking your vet: should the doxycycline be continued, adjusted or switched to a different antibiotic? When should the liver values be rechecked, ideally after the course ends? And has his urine been checked for protein? Veterinary guidelines recommend screening every Lyme-positive dog for protein loss in the urine, which can be an early sign of kidney involvement.

Call your vet promptly if you notice vomiting, a poor appetite, unusual tiredness or yellowing of the gums, eyes or skin. If the antibiotic is the cause, liver values often improve once it is stopped, but a recheck is the only way to know. Our guide to Lyme disease in dogs covers testing and treatment.

This is general information, not a diagnosis. Please follow your own vet's advice.