Two cats, one problem

Question
I took my two cats to the vet two weeks ago for teeth cleaning. My boy cat, 11 years of age began to walk funny as if his back legs were hurting him a few days after the vet visit. He had two teeth extracted, but seemed to do fine after the procedure. We took him back to the vet and she said it seemed to be his kidneys were infected, so she gave us clavamox. He took the clavamox for 7 days and about two or three days after stopping the clavamox, he began to walk funny again. The vet gave us more clavamox and he stopped walking funny after he was back on the clavamox.

Today, I noticed that the other cat, female, 9 years of age, began to walk a bit funny too. She is just kind of limping a bit and taking more cautious and shorter steps. She has a callus or "growth" on her front paw, but she gets these often. I cannot tell if this is the reason she is walking funny, but I feel it is too much of a coincidence that they are both displaying this behavior after a visit to our long time vet. This cat did not have any teeth extracted. In fact, the vet said her teeth were very clean and in great condition.

Both of them play, eat, sleep just as always. I see no other changes in behavior. Have you ever heard of this? Could the teeth cleaning have hurt them in some way to cause this behavior? Are there any infections that can spread through the litterbox that would cause them both to be walking funny?  

Answer
Dentals can cause infection due to the fact that the mouth of the cat is an area very rich in bacteria.  This is also the reason that cat bites are effective at causing infection in other cats and humans.  When extractions are done this both "stirs up" the present bacteria and creates open areas for bacterial invasion.  This does not necessarily manifest as limping, however your veterinarian was likely taking precautions that an infection had possibly occurred post procedure.  

There should not be anything passed in the litter box between the two cats that would cause limping.  If it is an infection it would more likely be a coincidence due to the dental, and I would consider having them checked for urinary infection which would not directly cause limping, however could cause unusual movement due to discomfort.  

An external consideration in limping cats is to check for Lyme Disease.  Though this is not as large a problem in cats as in humans and dogs this can happen and since both of your cats are limping, you may wish to check with your veterinarian to see if your areas has a high exposure rate.  

I hope this helps.  Please feel free to write back with any further questions.