Table A.

Some observations from the veterinary clinical practice

FISS: Feline injection-site (fibro)sarcoma 128-130	Feline injection-site fibrosarcoma are attributable to vaccination and administration of other pharmaceutical products. The tumours can spread along fascial planes and frequently reoccur after surgical removal. Nevertheless, benefits of vaccination clearly outweigh the cancer risks. Development of sarcomas at the site of repeated trauma or foreign body implants could be demonstrated in rats via the injection of food colourings, soya oil, iron derivatives or the implantation of solid materials, including plastic films. These findings were suggested to be due to the induction of chronic inflammation and subsequent cell metaplasia and gave rise to concerns over implants and prostheses used in human medicine. However, available evidence does not suggest these are associated with higher cancer risks. Possible etiologic factors for feline injection-site sarcomas include single nucleotide polymorphisms of feline p53 and upregulation of genes also differentially expressed in human soft-tissue sarcomas like FAP (fibroblast activation protein α) and PRAME (preferentially expressed antigen in melanoma).
Cancer in budgerigars (Melopsittacus undulatus) 131-134	It was observed in veterinary practice that there is a higher cancer rate in budgerigars than in all other ornamental birds. Most frequently recognized where renal and haematological neoplasia. The aetiology for the high susceptibility of budgerigars to neoplasia remains an unsolved mystery, but several lines of reasoning led to the suggestion of a retrovirus as a common causative agent. Nevertheless, investigations could not find evidence of an exogenous, replicating retrovirus using primary cell cultures of kidney tissue from budgerigars with renal neoplasia, amongst other material. However, in the case of myeloblastic myeloid leukosis in budgerigars, the subgroup J avian leukosis virus was found to favour myeloblastosis and myelocytomatosis. The Aves polyomavirus 1 (APV) was frequently observed in young budgerigars to be associated with inflammatory diseases and the common yeast infection macrorhabdiosis (caused by Macrorhabdus ornithogaster) provides a possible explanation for increased cancer incidences in those birds as chronic inflammation provides an underlying basis for the development of cancer.
Equine Sarcoids and bovine papillomavirus 135-139	Papillomaviruses were previously thought to be species-specific, but infection to accidental hosts can occur and commonly results in a in a different pathological outcome to that in the normal host. Cattle warts induced by the bovine papillomavirus (BPV) are benign tumours and generally regress without eliciting any serious complications. In equids, including horses, donkeys, mules and zebras the BPV can cause so-called equine sarcoids. Despite being classified as benign these sarcoids cause a high morbidity in the equids and not infrequently lead to the decision to euthanize the animal. The tumour commonly occurs on multiple body-locations, rarely regresses and very often recurs after surgical excision. While in the early 20th century inoculation experiments already led to speculations suggesting an infectious agent as causative agent, it remains unclear how the bovine papillomavirus reaches the equids. In cattle, BPV is transmitted by contact between animals or contact with fomites. Speculations in transmission to equids include face flies (Musca autumnalis) as potential vectors, infectious cell lines in analogy to canine transmissible venereal tumours or, as BPV1 RNA isolated from equine sarcoids was found to encode a unique deletion, it was even suggested that a novel variant of virus had evolved in equines. So far, no evidence has emerged supporting any hypothesis. Standard treatment includes surgery, chemotherapy and immunotherapy including the off-label use of Bacille de Calmette et Guérin (BCG) vaccination.