KAHLER: Rat needs lemon-sized tumor removed

Lily the rat has a lump that's grown from the size of a pea to the size of a lemon.

Darla admits to procrastinating in getting Lily to the vet: She is afraid the tumor is cancerous and that Lily won't be able to handle surgery.

The mass is quite large, especially when compared with Lily's overall body size. This does not mean that we can not help Lily. I have done surgery on tumors that literally weighed more than the patient. It does not sound as though Lily's tumor is quite that large, but it still presents a challenge to the patient and the surgeon.

Darla's concern about the tumor being potentially cancerous is valid, but most external tumors in rats are not cancerous. I think rats are often thought of as cancer producers because of their history in the laboratory in cancer testing. In Lily's case, odds are greatly in her favor that the mass is not malignant.

Blood loss is a real concern during surgery. Then there's the matter of the amount of blood contained in the tumor. Removing that amount of blood volume all at once can greatly stress the circulatory system, and especially the heart.

Remember, the heart is the pump that pushes the blood all around the body and maintains appropriate blood pressure. If the heart is suddenly presented with a greatly reduced volume of blood, as would be the case with removal of a large tumor full of blood, there can be a precipitous drop in blood pressure, which could be disastrous for the patient. We must keep these two factors in mind during surgery.

Radio-surgical or laser instruments will help keep bleeding to a minimum. Dealing with the shear volume of blood loss with the tumor's removal is more complicated.

As the tumor is exposed, the vessels supplying and removing blood to the tumor will also be exposed. Each of these needs to be blocked off individually to allow the heart to adjust to the decreasing blood volume. In this way, the heart is not suddenly presented with a significant loss in blood volume, leading to a blood pressure loss. When allowed to compensate more slowly, the heart can more easily maintain normal blood pressure.

Provided Lily is healthy and there are no other problems, this procedure will greatly improve Lily's quality of life.

Jeff Kahler is a veterinarian in Modesto. Questions can be submitted to Your Pet in care of LifeStyles, The Modesto Bee, P.O. Box 5256, Modesto 95352.