Palladia: First Drug to Treat Skin Cancer for Dogs

Estimated 74.8 million owned dogs in the United States 2007 - 2008 and thirty-nine percent U. S. households own at least one dog, according to the American Pet Products Manufacturers Association. 1 One of the worst dog diseases pet owners are most concerned is canine cancer: Dogs can suffer discomfort, pain and shortened life expectancy. 2 "The skin is the most common site of cancer in the dog (Four categories and the worst diagnosis is melanomas - "cells that provide pigment in the skin." 3) and the second most common site of cancer in the cat." 3 In the United States estimated 1.2 million new canine cancer cases are reported (Pfizer Animal Health). 13 Fortunately most dog cancers are benign (not malignant or harmless). 3 Dog skin cancer is characterized by symptoms, diagnosis, and sometimes preventable. In 2009 the Food and Drug Administration approved a drug to treat dog skin cancer (First Time). 2

Cancer of any kind begins when mutated cells form, re-produce, attack normal healthy cells and form cancerous tumors. A localized cancerous (malignant) tumor may spread or metastasize to other parts of the body. When cancer is detected and treated early, less likely the cancer will metastasize. 2

Frequently middle aged or older dogs (6 - 14 years old) are more likely diagnosed with skin cancer and several younger breed dogs. 3 "If a dog is strong and healthy, the immune system can stop the cancer cells from developing and spreading." When canine cancer metastasize, often spread to the lungs, causing respiratory breathing difficulties, may lead to death. 2

Certain breeds of dogs are more perceptible to canine cancer: Bull Mastiffs, Basset hounds, boxers, Scotish terriers, Kerry blue terriers, Norwegian elkhounds, and Weimaraners. 3 Possible causes of dog cancer: Poor quality pet food, Toxic exposure to chemicals ("e.g. from flea or tick control products), regular exposure to various forms of radiation (e.g. TV, x-ray), artificial flavors and coloring in pet foods, dirty drinking water, and polluted air (exposure to second hand smoke and gas exhaust). Some veterinarians believe over - vaccination is linked to cause cancer. When dog's have weak immune System's related to a lack of physical attention, boredom, depression or anxiety more prone to develop cancer (Not necessarily cancer of the skin). 2 Dog skin cancer appears as a lump on the surface of the skin or below the skin or sore that does not heal. A dog may scratch, itch, chew or feel discomfort on the affected area of the skin. 3 Veterinarians use diagnostic tests such as a biopsy, blood test, urinalysis, and x-ray confirm or exclude canine or skin cancer. 4

A Veterinarian decides upon the best course to treat a dog's skin cancer, depending upon information gathering during the examination and test results. Surgery can remove tumors or benign skin tumor. Ideally the incision should remove 1 1/2 to 2 inches of healthy tissue surrounding the potential malignant tumor. However malignant tumors tend to spread to other parts of the body despite surgical intervention or re-appear on the surgical site. Other options to treat dog skin cancer may follow surgery or tailored without surgery: Radiation therapy, chemotherapy, Cryosurgery (freeze the tumor with liquid nitrogen), and Photodynamic Therapy ("It involves giving the patient an intravenous drug and then exposing the tumor to a laser light."). 5

In June 2009, The Food and Drug Administration approved Pfizer Animal Health Inc. drug Palladia (generic name: toceranib phosphate 12): First drug made specifically to treat a type of skin cancer in dogs - canine cutaneous mast cell tumors (Most prevalent canine skin tumor 8). 6 This type of tumor can vary in size, shape and gross appearance on the dog's skin. Mast cell tumors are common in Labrador retrievers, Golden retrievers, Shar Peis, boxers, and Boston terriers. 7: Hereditary and environment link are speculated origins 9 Most common location for mast cell tumors on the thorax followed by the hind-limb, abdomen, forelimb, perineal area, neck and head. 7 Symptoms of mast cell tumors include blood in the Stool, vomiting and some dogs have abnormal blood clotting. "Most cell tumors are "graded" as to how likely they are to be malignant." A high grade is indicative of a more serious tumor. Cell tumors are measured according to the tumor stage ranging from zero to four (metastasis). 9 The lump of a mast cell tumor may fluctuate in size with inflammation like swelling and redness. 10

Bernadette Dunham, director of Food and Drug Administration center for veterinary medicine said: "Prior to the approval (Palladia), veterinarians had to rely on human oncology drugs, without knowledge of how safe or effective they would be for dogs." 6 According to Federal Law veterinarians can administer human cancer medication and treatments under controlled supervision. 11 Palladia works killing tumor cells by cutting off blood supply to the tumor or a tyrossine Kinase inhibitor. 6 Palladia is administered as a pill (prescription only) and taken every other day for several months. During clinical trials the medication reduced or stopped the growth of skin cancer in about sixty percent of dogs. 13 "Palladia will be become available for general purchase until early 2010." Until the time the medication is available, Pfizer will educate specialists regarding the clinical results of this therapy. 14 Common side effects of the medication: Weight loss, blood in the stool, decrease or loss of hunger and weight loss. 6

References:

1.) U.S. Pet Ownership Statistics - http://www.hsus.org/pets/issues_affecting_our_pets/pet_overpopulation_and_ownership_statistics/us_pet_ownership_statistics.html

2.) Dog Cancer - http://www.natural-dog-health-remedies.com/dog-cancer.html

3.) Skin Cancer in Dogs - http://www.petplace.com/dogs/skin-cancer-in-dogs/page1.aspx

4.) Skin Cancer in Dogs - http://www.petplace.com/dogs/skin-cancer-in-dogs/page2.aspx

5.) Skin Cancer in Dogs - http://www.petplace.com/dogs/skin-cancer-in-dogs/page5.aspx

6.) FDA approves cancer treatment for dogs - http://news.yahoo.com/s/ap/20090603/ap_on_he_me/us_med_dogs_cancer_drug;_ylt=AqWl89gn1oqIdnBG7gjEqXXVJRIF;_ylu=X3oDMTJvZDlwaTEwBGFzc2V0A2FwLzIwMDkwNjAzL3VzX21lZF9kb2dzX2NhbmNlcl9kcnVnBGNwb3MDMQRwb3MDMQRzZWMDeW5fdG9wX3N0b3J5BHNsawNmZGFhcHByb3Zlc2M-

7.) Veterinary Clinical Patholgy Clerkship Program - Clinical Presentation - http://www.vet.uga.edu/vpp/CLERK/Nesbit/

8.) Canine Mast Cell Tumors - http://www.addl.purdue.edu/newsletters/1998/winter/cmcts.shtml

9.) Canine Mast Cell Tumors: A Common Cancer in Dogs - http://www.peteducation.com/article.cfm?c=2+1638&aid=461

10.) Canine Cutaneous Mast Cell Tumours - http://www.vetspecialists.co.uk/06_Animal_Welfare/Oncology_Facts/Canine_MastCell_Tumour.html

11.) FDA approves Palladia, first canine cancer drug made just for dogs - http://www.nydailynews.com/lifestyle/2009/06/03/2009-06-03_fda_approves_cancer_drug_for_dogs.html

12.) FDA approves drug to treat cancer in dogs - http://www.upi.com/Science_News/2009/06/03/FDA-approves-drug-to-treat-cancer-in-dogs/UPI-60081244039573/

13.) FDA Approves Pfizer's Canine Cancer Treatment - http://www.redorbit.com/news/science/1699887/fda_approves_pfizers_canine_cancer_treatment/index.html?source=r_science

14.) Pfizer earns FDA approval for canine cancer pill - http://www.theday.com/re.aspx?re=b594b701-9b75-4837-baa9-7db1b722dd2f