貓咪: Oscar,Minou,Shandie,
威望: +2
級別: 天神
魅力: 
經驗: 
財產: 277116 喵元
來自: 保密 
總發言數: 17128 篇
註冊日期: 2003/12/16
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History
VAS was first recognized at the University of Pennsylvania School of Veterinary Medicine in 1991.[2] An association between highly aggressive fibrosarcomas and typical vaccine location (between the shoulder blades) was made. Two possible factors for the increase of VAS at this time were the introduction in 1985 of vaccines for rabies and feline leukemia virus (FeLV) that contained aluminum adjuvant, and a law in 1987 requiring rabies vaccination in cats in Pennsylvania.[3] In 1993, a causal relationship between VAS and administration of aluminum adjuvanted rabies and FeLV vaccines was established through epidemiologic methods, and in 1996 the Vaccine-Associated Feline Sarcoma Task Force was formed to address the problem.[4]
In 2003, a study of ferret fibrosarcomas indicated that this species also may develop VAS. Several of the tumors were located in common injection sites and had similar histologic features to VAS in cats.[5] Also in 2003, a study in Italy compared fibrosarcomas in dogs from injection sites and non-injection sites to VAS in cats, and found distinct similarities between the injection site tumors in dogs and VAS in cats. This suggests that VAS may occur in dogs.[6]
Pathology
Inflammation in the subcutis following vaccination is considered to be a risk factor in the development of VAS, and vaccines containing aluminum were found to produce more inflammation.[7] Furthermore, particles of aluminum adjuvant have been discovered in tumor macrophages.[8] The incidence of VAS is between 1 in 1000 to 1 in 10000 vaccinated cats and has been found to be dose-dependent.[1] The time from vaccination to tumor formation varies from three months to eleven years.[9] Fibrosarcoma is the most common VAS; other types include rhabdomyosarcoma, myxosarcoma, chondrosarcoma, malignant fibrous histiocytoma, and undifferentiated sarcoma.[10]
Similar examples of sarcomas developing secondary to inflammation include tumors associated with metallic implants and foreign body material in humans, and sarcomas of the esophagus associated with Spirocerca lupi infection in dogs and ocular sarcomas in cats following trauma. Cats may be the predominant species to develop VAS because they have an increased susceptibility to oxidative injury, as evidenced also by an increased risk of Heinz body anemia and acetaminophen toxicity.[9]
[edit] Diagnosis
VAS appears as a rapidly growing firm mass in and under the skin. The mass is often quite large when first detected and can become ulcerated or infected. It often contains fluid-filled cavities, probably due to its rapid growth.[11] Diagnosis of VAS is through a biopsy. The biopsy will show the presence of a sarcoma, but information like location and the presence of inflammation or necrosis will increase the suspicion of VAS. It is possible for cats to have a granuloma form after vaccination, so it is important to differentiate between the two before radical surgery is performed. One guideline for biopsy is if a growth is present three months after surgery, if a growth is greater than two centimeters, or if a growth is becoming larger one month after vaccination.[1]
X-rays are taken prior to surgery because about one in five cases of VAS will develop metastasis, usually to the lungs but possibly to the lymph nodes or skin.[8]
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