The Dog Cancer Survival Guide (124 page)

To reduce the risk of ulcers, give piroxicam with food. You should also follow the dosing instructions exactly; even a small overdose can result in severe toxicity. If your dog is smaller than 70 pounds, your vet will need to get you compounded pills to accurately dose her. I often prescribe misoprostol to take along with piroxicam, because it can help prevent ulcers.

Some dogs, receiving high doses of piroxicam, have developed kidney toxicity, and long-term administration can cause irreversible damage. The kidney values and urine must be regularly monitored (every four to six weeks) while on this drug, and if your dog develops kidney issues, the dose must be lowered or the drug stopped. The medication must not be used at all, if your dog has pre-existing kidney disease.

Piroxicam can sometimes affect the function of the platelets, which leads to a lack of coagulation in the blood. This can cause bleeding that is difficult to stop, so make sure you report any history of a bleeding disorder to your vet before using piroxicam. It’s also a good idea to stop piroxicam a few days before surgery to prevent bleeding issues on the operating table, but check with your veterinarian or surgeon for specific recommendations.

Piroxicam must not be used with any other anti-inflammatory or NSAID, including aspirin, ibuprofen, carprofen (brand name Rimadyl), meloxicam (brand name Metacam), deracoxib (brand name Deramaxx), Tylenol with codeine, prednisone, methylprednisolone or budesonide. All of these drugs potentially cause stomach ulcers, and combining any with prednisone can really increase this risk. Using Apocaps with piroxicam warrants special instructions, which can be found on
page 169
. If your dog has ever been sensitive to or allergic to any of these medications, do not use piroxicam.

When a cell reproduces, it copies itself and divides in two. All cells, including cancer cells, go through the same series of steps when they do this. These steps, taken together, are called the cell cycle.

Each step in the cell cycle builds on the one before. If something goes wrong at any step along the way, reproduction may halt completely or, depending upon when the problem occurs, there may be permanent damage to the cell’s DNA, preventing later replication or even causing cell death. Chemotherapy drugs, by and large, work by interrupting the cell cycle at one of these steps. Because actively dividing cells are more sensitive to DNA damage, chemotherapy is most effective against rapidly dividing tumors.

To vastly over-simplify the cell cycle for our purposes, the basic steps are these:

• The cell takes in nutrition and grows, accumulating the enzymes, ribonucleic acid (RNA), and proteins necessary for division. This phase is called the Gap 1 or G1 phase.
  
• The cell uses proteins to duplicate its DNA, using a substance called ribonucleic acid (RNA), which is similar in form and function to DNA. The process of DNA replication is complex and involves many steps, each of which must be performed perfectly. This is called the Synthesis or S phase.
  
• The cell continues to grow and readies itself for the cell division. This is called the Gap 2 or G2 phase and is the second period of RNA and protein synthesis.
  
• The cell stops growing and splits itself into two separate cells. These are sometimes called “daughter” cells, and each has (ideally) its own identical copy of the original cell’s DNA. This is called the Mitosis or M phase.
  
• The cell stops dividing and enters a resting phase, during which it is relatively quiet and inactive. This is called the Gap 0 or G
  ₀
  phase, and it lasts until the cell must divide again, when the cycle starts over.
  

Most chemotherapy drugs work by attacking the cell, while it prepares for mitosis, by damaging the DNA and/or RNA. Depending upon the drug’s actions and where in the cell cycle it has its affect, chemotherapy can stop cell division, kill the cell directly and/or induce apoptosis (natural cell suicide). As you’ll find out, some of the common chemotherapy drugs work only during very specific phases of the cell cycle. Thus, they may be given to your dog over a long period of time – 12 to 24 hours – so that the drug has a chance to kill as many cancer cells as possible as they pass through the sensitive phase of the cell cycle.

You’ll remember that cancer cells have a survival advantage over normal cells because they divide without regulation, becoming more susceptible to chemotherapy drugs. That’s why oncologists typically turn to chemotherapy when a tumor is rapidly dividing or at a high risk for metastasis. This is also an explanation for chemotherapy’s expected side effects: rapidly dividing cells, including the hair follicle, the lining of the gastro-intestinal tract and the white blood cells, are often affected by chemotherapy drugs.

Tumors are typically found when they are about one centimeter in diameter, and this does not seem large to most owners or vets. But realize: a one-centimeter tumor contains about one billion cancer cells!

There’s another problem with these one-centimeter tumors. By the time a tumor reaches this size, a significant number of its cells have entered the G
₀
or resting phase, and are therefore resistant to chemotherapy. Of course, those cells usually rejoin the cell cycle and become sensitive to chemotherapy again, which is why we give chemotherapy treatments over time.

“Angus is a nine year-old Golden Doodle. He’s the best dog we have ever had. We’ve always said he’s like a human in a dog suit. He’s always been there for us, always attentive, always ready to put his head on your lap, always ready to give love. Plus, he was fast. He looked like a thoroughbred when he ran. In June of 2010, my wife, Barb, was down at our house on the beach helping our daughter start up a restaurant and noticed him limping and staying off his rear leg. She drove him down to our “beach vet” to be checked and was diagnosed with osteosarcoma. He was one of the favorites at the vet’s office and all of the “girls” who worked there were bawling along with my wife. When Barb got him back to the house, she called me and told me to sit down and laid it out -- the vet had said that, without treatment, Angus’ prognosis was 6 -8 weeks as this was an extremely aggressive and lethal cancer. We must have cried on the phone for two hours. At the time, it was one of the most gut-wrenching things we had been through. It paled, however, compared to the death of our son, Dave, 5-months later (for which there is no comparison). Barb’s someone that springs to action. She got on the phone and made an appointment with a leading veterinary oncologist in the Raleigh area (where we live), wrapped up a bunch of restaurant-related details, found Dr. Dresser’s book on the internet and sent me the link, packed up her truck and got him back for a consultation. After consultation with the specialist, we signed up for amputation and a 4-week course of carboplatin, hearing that it could extend his life by 6 months and, maybe if we were lucky, a year. I printed out Dr. Dresser’s book, put it in a 3-ring binder, and started reading. I had always been big into supplements, so was drawn to the chapters on alternative therapies. I probably read those chapters about 10 times before it started sinking in and we started off adding just a couple supplements to his meals and giving him purified water instead of tap water. Angus went in for amputation surgery on July 1,2010 and we spent a long 4th of July weekend lying on the floor with him to reassure him and keep him from chewing his stiches out. Obviously, the wound was pretty gross. Like all good dogs, he kept licking our faces after we had just brought him in to have a leg chopped off. Cancer mechanisms and alternative treatments became our new obsession; I spent hours researching after work every night, reading Dr. Andrew Weill, Dr. Russell Blaylock, internet blog after internet blog, and as many clinical studies and papers I could find on medicinal mushrooms and artemisinin. Surprisingly, I found Suzanne Somers’ book Knockout to be superb. The more research we did, the more we fine-tuned Angus’ regimen. I’m now a big believer in the theory of dogs self-medicating. We’ve never had to force pills down Angus’ throat. He either eats them with his dinner or out of our hand...I persuade myself that he does this because he senses it will help cure his cancer. It’s now 10 months since Angus was diagnosed. He has had to survive the stress of our grieving the loss of our son. And the stress of that event on him -- he knows...But, we have doubled our efforts to support Angus in dealing with his cancer. We aren’t willing to lose two of our “boys” in the same year. Angus has been back to the oncologist twice for scans to see whether the cancer has spread (most dogs with osteosarcoma die when it spreads to their lungs). On both earlier visits, nothing showed on the scans and his blood counts were phenomenally good. He’s still bright eyed and has a good appetite. We want to get him another summer at the beach. He’s a great dog, a great friend. He deserves it.”

- Al Marzetti, Raleigh, North Carolina