VINCRISTIN SULFAT, EFFECTIVE CHEMOTHERAPY FOR VENEREAL SARCOMA THERAPY IN DOGS

Venereal sarcoma  or also called Transmisable Veneral Tumor (TVT) is a malignant tumor that often attacks dogs, especially in male and female genital organs. This tumor is transmitted from one dog to another through sexual contact. Male dogs can be infected by female dogs or vice versa female dogs can be infected by male dogs when sexual intercourse occurs. The cause of this tumor is not yet known with certainty. Transmission occurs because at the time of sexual contact, tumor cells come off and stick to the penis or vagina and then the tumor cells have proliferation in the tissue. Dogs of all breeds and all ages can be infected, but generally cases of venereal sarcoma are found in dogs aged 2 to 5 years 

These tumors generally attack the genitals (genital), but sometimes can also be found outside the genitals (extra genital) for example on the nose, eyes, gums and lips. On the female genitals tumors are seen in the vulva and vagina while in male dogs tumors found in the penis gland to the base of the penis and prepuce. Extra-genital venereal sarcoma arises from the dog's habit of sniffing or licking the affected genitals and the tumor cells being detached and attached to the nose, eyes or lips mucosa. Clinical signs are usually characterized by the presence of small reddish papules that develop into nodules and multilobus papillae such as cauliflower and blood drops. Blood dripping from the genitals is caused due to rupture of the tumor and can be confused with the condition of estrus, urolithiasis, cystitis or prostatitis. If there is a secondary infection, the genitals of the dog will secrete serosanguinius and foul smelling.

Venereal sarcoma often occurs in wild dogs due to uncontrolled sexual behavior. But this case has also been reported to occur in domestic dogs that have not been neutered or have been neutered. The infectious agent of venereal sarcoma is a living tumor cell itself and is not caused by a virus or a virus-like organism. Tumor metastases are generally rare, but if they occur, tumor cells are usually found in regional lymph nodes, kidneys, spleen, liver, eyes, tonsils, brain, pituitary, skin and subcutaneous tissue, nasal cavity, oral cavity, mesenteric lymph nodes, and peritoneal lymph nodes.

 Venereal sarcoma therapy can be done with surgery, chemotherapy and radiotherapy. One commonly used chemotherapy is vincristin sulfate. Vincristine sulfate has been used extensively as a single chemotherapy agent for handling sarcoma venereal cases. Therapy with vincristine sulfate is generally carried out for four to seven weeks intravenously at a dose of  0.025 mg / kg body weight depending on the severity of venereal sarcoma and the dog's resistance to chemotherapy. In the initial case with mild severity vincristin sulfate given alone effectively cured the venereal sarcoma. 

In severe cases chemotherapy with vincristine sulfate accompanied by surgery is the most effective venereal sarcoma treatment method compared to single surgery therapy or therapy with single vincristine sulfate. Handling of venereal sarcoma cases with surgery accompanied by chemotherapy not only accelerates the healing process, but also can reduce the amount of chemotherapy drugs that enter the animal's body, so as to minimize the side effects caused by using chemotherapy drugs. Treatment of venereal sarcoma which begins with surgery only requires 2- 3 times chemotherapy with vincristine sulfate, healing will occur faster and no recurrence occurs. While in the case of  venereal sarcoma which is only treated with single vincristine sulfate without surgery, it requires repeat chemotherapy up to 5-7 times to clear the tumor mass.

Vincristine is a chemical compound of the vinca alkaloid derived from the Vinca rosea plant. This compound is a chemotherapy agent that is widely used to treat various neoplastic disorders, such as lymphoma, leukemia, and sarcoma in dogs and cats. Vinca alkaloids are cytotoxic and cause hypoglycemia in cells. These compounds work by binding to tubulin proteins so that the formation of microtubules is inhibited. This causes the cell to be unable to separate its chromosomes during metaphase so that the cell undergoes apoptosis and replication failure.

The mechanism of action of chemotherapy drugs is not selective, so in addition to destroyed cancer cells, normal cells that are actively dividing such as bone marrow cells, digestive tracts, hair follicles, and the reproductive system are also affected. The administration of chemotherapy agents is also myelosuppressive, causing a decrease in hematological value. This myelosuppressive nature results in a decrease in the production of red blood cells, platelets, and some white blood cells by the bone marrow. Side effects of vincristine sulfate include paresis (peripheral neuropathy), anemia, leukopenia, thrombocytopenia, constipation, nausea, vomiting, and anorexia. Provision of vincristine sulfate in the long term besides causing severe myelosuppressive can also reduce the animal's immune system (immunosuppressive). Therefore its use in dogs is limited to a maximum of 7 times with a 7-day interval. If after 7 times the sarcoma venereal has not healed, the administration should be stopped and use another therapy.

Cases of  venereal sarcoma that have been treated using vincristin sulfate at a dose of 0.025 mg / kg body weight so far have shown effective results. In cases that are still mild / initial and small tumors, the use of vincristin sulfate alone with 2 to 3 repetitions gives satisfactory results. Meanwhile, if the tumor is large, the choice of therapy with surgery accompanied by administration of vincristin sulfate also gives satisfactory results. Surgery aims to remove the tumor as much as possible and vincristin sulfate will kill the remaining tumor cells. With a combination of surgical therapy and chemotherapy, the use of vincristin sulfate is reduced so that it can reduce the side effects of vincristin.

      Vincristin sulfate at a dose of 0.025 mg / kg body weight intravenously at 7-day intervals, its use can be recommended for dogs with  venereal sarcoma sufferers with satisfactory cure rates.