I thought it would be nice to relate a story highlighting the importance of a sustained relationship with a family veterinarian.

Oliver is a 5-year-old Papillon mix. Judging from the fact that his owner came to us from Hilton Head Island, and that her father accompanied her for the appointment, and her mother for the discharge, and from the alternating expressions of love and concern for little Oliver, it was obvious that he occupies a special part of an extended family.

Oliver's medical records were complete and regular. Vaccination history, annual physical exams, medications, etc. It was all there. It was a testament to the commitment, on the owners part, to the health of their dog.

The records displayed the work of a thorough veterinarian. This may not have stood out to me, as much as it did if it hadn't been for the nature of the visit. Oliver was here for a tumor. Not some external skin tumor, visible to the whole world. Oliver had a tumor of the anal sac.

For those who aren't familiar with this bit of dog anatomy, the anal sacs sit within the anal sphincter. They are at about 4 and 7 o'clock, and serve to produce a very unpleasantly scented liquid that is used as a territorial marker. These are the same structures that produce the spray that skunks emit when threatened. The contents also are often expelled in our examination rooms, as dogs sometimes feel threatened in there. I took a quick look under the tail, but the mass was unapparent. I then put on the dreaded glove. As I performed the exam, my first thought was, "Great, these people have come all the way from Hilton Head, and there is no tumor."

At first, I could not feel a thing. The problem is that I was expecting what I always seem to feel; a large olive size, or larger, tumor that cannot be missed. I usually then feel further in and find that the lymph nodes are also involved.

I had to ratchet down my expectations, and then it came into focus. This mass was indeed there, but it was tiny. The size of a ladybug, at best.

The tumor type is known as an apocrine gland adenocarcinoma of the anal sac. This is the most common tumor type affecting the anal sac. They affect males and females equally, but certain breeds, such as Dachshunds and Spaniels, are more frequently affected. The average age is about 10 years.

These tumors, though relatively uncommon, are serious because they have a strong tendency to spread to local lymph nodes and eventually the lungs. They are usually fatal.

Part of the problem is their location. Owners don't examine that area, and the first sign they usually note is their dog's constipation and straining to defecate. They then take the dog to the vet, who finds a large anal sac tumor.

The problem is even worse than it seems, because the straining is usually caused by the internal lymph node tumor that you can't see.

This means that most of the time, by the time I see these cases, the tumor has already spread.

The prognosis is tied to the size of the tumor and whether it has spread to regional lymph nodes or distant sites. Overall, the average survival time for these patients is 15 months when treated surgically.

Chemotherapy definitely extends life expectancy when used in conjunction with surgery. But the best prognostic factors are early and complete removal of small masses that have not spread. These average a nearly three-year survival time.

Oliver's case was, by far, the earliest diagnosis I have ever seen. His surgery was uncomplicated and we were able to excise his small mass entirely.

Given its size and the fact that there was no evidence of spreading, I expect Oliver to be back at the center of his family for years to come, and it's really thanks to a regular and established relationship with a very thorough family veterinarian.

Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to petdocs@postandcourier.com.