Dear Petdocs,

I took my 5-year-old dog to the vet to be spayed, two weeks ago. Two days after she came home, she began limping badly on one of her back legs. Now my vet says she has a torn ligament in her knee. She had never had a problem with this leg before, and she was on cage rest after surgery.

My vet insists that nothing bad happened at his clinic, but seems like too much of a coincidence to me. I feel certain that something happened at their clinic, but I'm not sure what to do next. Any thoughts?

A: I would not normally get into a question like this, but it illustrates an issue common in veterinary health care. It seems, to some, that while a pet is under the care of a veterinarian, the normal rules of probability no longer apply. We can all accept that there is an array of illnesses and injuries that our pets are subject to.

We even know that for many, if not most, of these conditions, there are actually odds calculated that an individual will experience a given illness. But, for some reason, people find it hard to accept that these odds apply at all times, including during visits to the veterinarian. If a problem develops while a pet is at the vet, more often than not, suspicion falls upon the DVM.

Although it is certainly possible that a problem could be caused by a clinic, or doctor, one must keep an open mind. Correlation does not, necessarily, mean causation. Just because something happens around the time of a vet visit, it was not necessarily caused by the vet.

I can think of many examples where, at first glance, blame seemed to rest squarely with the vet, when the truth was that it was a true coincidence. I remember a particular case that involved me. It was a Dachshund, named Penny. She had presented to our clinic for a spinal problem. I performed an examination and discussed the option of surgery versus a more conservative approach.

Since the dog appeared stable, at least not worsening rapidly, I recommended that we wait another 24-48 hours before surgery was considered, to see if things improve on their own.

All we did that day was an examination and some X-Rays. We then sent her home for the evening. That night Penny developed diarrhea, which became profuse, and then bloody. Within hours, she was dead.

The owner called me and was hysterical. "What did you do to my dog?", she implored. She went on to state that she brought me a healthy dog with a back problem, and right after seeing us, she began bleeding and died. She was certain that we were at fault.

I began asking some questions, and it turned out that the night before, the owners mother had given the dog a massive dose of Advil. Ibuprofen is not meant for dogs and can cause severe gastrointestinal ulceration, perforation and hemorrhage. It struck me that I was very fortunate to have taken a conservative approach.

Had I performed surgery, the same thing would have happened, but the owner would have never believed that we were not at fault.

Your dog probably has torn her anterior cruciate ligament. This is actually the most common cause of lameness in an adult dog. Unlike people, dogs usually experience these tears in the absence of trauma. So, even if this happened at your vets office, it is unlikely that it was caused by them. Also, when this ligament is injured, the lameness is generally immediate. If this occurred at your vets office, lameness would have been immediate, not two days later.

So, when problems crop up around the time of a vet visit, take a step back, keep an open, objective mind, and consider all the possibilities.

Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. To send questions, go to Veterinaryspecialtycare.com and click the "ask the pet docs" icon.