What about chemo safety in dogs, anyway?
How do we know whether a given dog with cancer will tolerate chemotherapy?
Well, for some drugs, there is a test that can give us info. The test is for mutations in a gene called MDR 1, or ABCB delta 1. This gene make a protein that is responsible for pumping foreign agents (like drugs) out of body cells. When the pump does not work, toxicities are more likely. These toxicities can be dangerous, so it is wise to consider this before starting chemo, especially if your dog is one of the common breeds affected (see below).
Dogs with the MDR1 mutation may be more likely to have bad reactions to some chemotherapy agents including Vinblastine, Vincristine, and Doxorubicin. These reactions include possible suppression of a type of white blood cell (neutrophil), vomiting, diarrhea, and loss of appetite.
It is recommended that if the test shows mutations in the MDR 1 gene, the dose of these drugs be decreased by 25-30% and careful monitoring be conducted.
Long haired Whippets: 41.6%
Miniature Australian Shepherds: 25.9%
Silken Windhounds, Australian Shepherds, English Sheepdogs, McNabs, Old English Sheepdog, Shetland Sheepdogs: 0.9% or less
German Shepherds (no percentage available)
You can have your dog tested at Washington State (link). Print out the link page for your vet.
(FYI: There are several other drugs that are listed at WASU’s Clinical Pharmacology Lab, that can have increased chances of side effects with MDR 1 mutations, but have little to do with dog cancer directly: Ivermectin, Selamectin, Milbemycin, Moxidectin, Loperamide (Imodium) , Acepromazine, and Butorphanol.)
More tools coming up for dog lovers who want the goods on full spectrum canine cancer care!
Best to all,
Dr. Demian Dressler is internationally recognized as “the dog cancer vet” because of his innovations in the field of dog cancer management, and the popularity of his blog here at Dog Cancer Blog. The owner of South Shore Veterinary Care, a full-service veterinary hospital in Maui, Hawaii, Dr. Dressler studied Animal Physiology and received a Bachelor of Science degree from the University of California at Davis before earning his Doctorate in Veterinary Medicine from Cornell University. After practicing at Killewald Animal Hospital in Amherst, New York, he returned to his home state, Hawaii, to practice at the East Honolulu Pet Hospital before heading home to Maui to open his own hospital. Dr. Dressler consults both dog lovers and veterinary professionals, and is sought after as a speaker on topics ranging from the links between lifestyle choices and disease, nutrition and cancer, and animal ethics. His television appearances include “Ask the Vet” segments on local news programs. He is the author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity. He is a member of the American Veterinary Medical Association, the Hawaii Veterinary Medical Association, the American Association of Avian Veterinarians, the National Animal Supplement Council and CORE (Comparative Orthopedic Research Evaluation). He is also an advisory board member for Pacific Primate Sanctuary.