The Dog Cancer Survival Guide (38 page)

Those were public studies. One private, confidential study looked at private practice vets treating dogs, cats and rabbits. In this study, the number of dogs who died due to anesthetic accidents was one in seventy-five, or 1.33%, which is higher than at the specialty centers.

The more experienced the anesthesia administrator is, the better your dog’s chances of experiencing no or mild side effects. His general health is also a factor. In my experience, elderly dogs have a harder time with anesthesia than younger dogs do, and savvy clinicians will often use lower doses and gentler drugs because of this. If your dog has a known issue related to anesthesia, the protocols will be modified accordingly.

If you are really worried about anesthetic accidents, seek out a board-certified surgeon. Published studies show that patients tend to have better outcomes when surgeries are performed by surgeons who have advanced training and experience.

Depending upon your budget or your location, you may or may not be able to choose your surgeon. Even so, it’s worth finding out whether your vet is a “good driver” or a “bad driver” when it comes to anesthesia. You can do this by asking how many dogs have died in surgery in his practice, and how often he has seen serious side effects as a result of anesthesia. Measure his answers against the general statistics listed above and your own intuition, while you gently remind him how important it is to you for your dog to come out of the surgery with as few complications as possible.

Ketamine has been shown to increase the odds of tumor metastasis, when it’s used as an anesthetic. In a study done with rats as subjects, ketamine seemed to suppress the activity of natural killer cells, which probably made tumors more likely to metastasize, in the weeks after the anesthesia was administered. For this reason, I do not recommend using ketamine as an anesthetic when a dog has cancer.

Some vets, myself included, use very small doses of ketamine for pain control; at those low doses, it is safe for cancer patients.

In the same study, thiopental and halothane also increased metastasis, although not nearly as much as ketamine did. Although these agents are not usually used in veterinary medicine anymore, check with your surgeon to be sure. Propofol was also assessed during this study, and it was the only anesthetic not associated with suppressed natural killer cell activity.

Most veterinarians – especially those in rural areas – are general practitioners. Because they see a wide range of problems, they often have a wide base of experience. There is still a spectrum of skill levels. Depending upon their training, whether they have supervision from another, more experienced vet, and their opportunity to practice certain surgeries, some may be more experienced – and therefore more confident – than others.

Just like human physicians, veterinarians have personal preferences about how they practice medicine. Especially in urban areas, where vets can refer out to other vets or specialists, some vets may not do certain surgeries. I know one vet who refuses amputations, because he is uncomfortable with them. He hasn’t done enough to feel confident in his skills, and he’s willing to refer those surgeries to other vets.

It’s not rude to ask your vet whether he is comfortable with the surgery he’s proposing, and it’s important that you know the answer. Ask how common the surgery is, and how often he’s done it. If he’s not comfortable with the surgery, he will likely give you a referral.

I’ve been asked how many surgeries a vet needs to have done in order to be considered experienced, so I’ll share with you my very general rule of thumb: fifty. Once a vet has performed the same surgery fifty times, he is probably very comfortable with the procedure. Of course, if a surgery or technique is new, or if that surgery just hasn’t shown up in his practice, your vet may not have this level of experience.

Some guardians prefer to go to a specialist for surgery. If a board-certified surgeon is available in your area, at least consider consulting with her. After all, she spends every day in the operating room and will be more comfortable with complicated surgeries. There is some evidence that board-certified surgeons generally remove more tissue during surgeries, which results in cleaner margins. A few board-certified surgeons have also trained separately and are board-certified in oncological surgery. Whether you have the resources to hire “the best” surgeon or not, it’s important that you have a frank and open discussion with your vet about the proposed surgery, and that you listen to your gut when it’s time to make a choice.

Radiation therapy beams a large amount of energy (which is invisible to our eyes) into one area of the body. The energy is called “ionizing radiation” and usually consists of photons or electrons. This energy is strong enough to enter cells and affect their molecules. The radiation tears electrons out of their orbits, creating those unpredictable free radicals discussed in
Chapter 8
. These new free radicals damage the cell’s structure, most commonly by damaging its DNA.

As a result of this damage, the cell dies when it tries to divide and proliferate. Only the cells, which are dividing at the time of the treatment, will die immediately – others will die days or even weeks later, after they start to divide. This is why it can take a while – months, sometimes – for tumors to shrink, as a result of radiation therapy.

Radiation doesn’t just kill cancer cells. It can damage or kill any normal cells that get in the way, such as skin, mucous membranes, eyes, and any other organs that are in the path of the radiation beam.

The resulting side effects can be quite serious. For this reason, radiation is not used in all cancer cases, and when it is used, great care must be taken to spare as many normal cells as possible. The radiation oncologist carefully considers the field of treatment, noting any particularly sensitive areas or organs, like the lungs and the intestines. The total dose of radiation is determined by how much the most sensitive areas can handle with relative safety. To minimize damage even further, the dose is divided up into many small treatments (typically fifteen to twenty). These sessions, called fractions, are helpful, because normal cells can repair themselves more efficiently after smaller, multiple doses.

The need for a radiation oncologist, several treatments and anesthetic make radiation therapy very expensive.

The most common time to use radiation is after surgery, in an attempt to damage irreparably and kill any microscopic cells left in or around the surgical site.

Radiation may also be considered when there is a discrete tumor, large enough to be seen with the naked eye: especially a tumor that has not metastasized or is not prone to metastasize. It’s also considered for tumors that cannot be removed with surgery (inoperable or non-resectable tumors).

Some cancers respond well to radiation, including lymphoma (a lymphoma tumor can shrink to half its size after just one treatment), perianal adenoma and perianal adenocarcinoma, plasmacytoma (plasma cell tumor) and transmissible venereal tumors.

Other cancers are less responsive to radiation, but can be good candidates, depending upon the case: nasal tumors, mast cell tumors, squamous cell carcinoma, fibrosarcomas and nerve sheath tumors (hemangiopericytomas). Depending upon the individual tumor and the intent of the radiation treatments, these cancers might be reduced a moderate amount or slowed in their growth. In other cases, they may respond well, but the effect might be temporary (weeks’ or months’ duration).

Another use for radiation is as palliative therapy. In these cases, the goal of radiation is not to destroy the cancer completely, but to reduce the size of the tumor(s). If the tumor is pressing on nerves, organs or bones, shrinking it can reduce pain. Tumors that are obstructing important areas, like the urinary tract or prostate, may also be candidates for radiation therapy.

Radiation therapy seems to have a pain-relieving effect. For example, dogs who receive palliative therapy for osteosarcoma usually experience a lessening of pain within seven days of treatment, and that affect lasts four to six months. We’re not entirely sure why their pain lessens, but we speculate that neurotransmitters (called endorphins) are released by the procedure. Endorphins are the body’s natural opiates, or pain relievers. Dogs who receive palliative radiation may need less pain medication.