Lymphoma, a cancer that involves the spleen, liver and other organs, does not have a great prognosis when diagnosed in dogs. Some dogs relapse, even after enduring surgery and receiving chemotherapy. Dacarbazine is a chemotherapy drug that is effective in treating dogs with relapsed lymphoma.
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Description
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Dacarbazine decreases tumor growth and multiplication by interfering with the DNA of tumor cells. Dacarbazine is usually not included as an initial protocol for lymphoma. It is used in a rescue protocol for dogs that have relapsed after receiving regular chemotherapy treatments. It is administered in conjunction with other chemotherapy drugs, such as doxorubicin or dactinomycin.
Administration
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Dacarbazine is administered intravenously. It is given to dogs as a slow IV drip, in small doses, once a day for five days, or a higher dose is given over a two- to eight-hour period, every three weeks. The IV must be carefully placed and removed to avoid complications.
Side Effects
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Although dogs seem to tolerate dacarbazine better than other chemotherapy drugs, it does have side effects. Some of these include nausea, anorexia and vomiting. Also, the drug can cause bruising and pain at the site of injection. According to Withrow and MacEwen's "Small Animal Clinical Oncology," approximately 50 percent of dogs vomit during administration of the treatment, and about 30 percent show signs of distress.
Effectiveness
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Dacarbazine is usually not effective as a single treatment. Accordingly, it is issued in conjunction with doxorubicin, another chemotherapy drug. Cancer cells have been shown to develop a resistance to doxorubicin, but when combined with dacarbazine, a dog's survival rate increases and the chances of relapse decreases. According to "The Journal of Veterinary Internal Medicine," a study of 15 dogs that had relapsed and were treated with a dacarbazine protocol showed the average survival time as 45 days. Five dogs responded favorably to the first round of treatment and survived an average of 105 days. Three dogs were responsive to a second treatment.
Precautions
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Dacarbazine is considered highly corrosive to tissues, therefore an IV drip should be carefully placed on and removed from the dog to prevent damage to the surrounding skin area. The injection site must be monitored for inflammation or irritation. Antiemetics, drugs that reduce vomiting and nausea, should be administered for dogs that are receiving higher doses of a dacarbazine protocol to reduce the severity of symptoms.
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