Table 6.6 Factors known to be associated with the onset of cancer

Factor

Neoplasm

Examples of known associations

Advancing age Most tumours Mean peak incidence occurs at 8 years of age
Genetic susceptibility
It is now generally accepted that there is a genetic basis to neoplasia; purebreds are more susceptible than crossbred animals
Chemical carcinogens (or their metabolites), and UV radiation all cause DNA damage and are mutagenic
Osteosarcoma
Multiple primary neoplasia
 

Intranasal tumors
 
Malignant melanoma (skin)
Giant breeds of dog
The boxer especially mast cell tumors, lymphosarcoma, squamous cell carcinoma and osteosarcoma
Doliocephalic breeds, e.g. Shetland sheepdogs, collie and German shepherd dog
Heavily pigmented breeds e.g. Scottish terrier, cocker spaniel
Sex hormone-related neoplasia Female hormones (progesterone)

Male hormone (testosterone)
Mammary neoplasia
 
Prostatic neoplasia
Perianal adenoma
Parasitic Oesophageal cancer Spirocerca lupi in dogs
Viral Lymphosarcoma or leukaemia
 
 
Papilloma
 
 
Fibrosarcoma
Cats - gastrointestinal tract neoplasia associated with feline leukaemia virus
 
Self-limiting disease (usually seen as oral papillomatosis) in young puppies
 
Cats - due to feline sarcoma viruses (FeSV) - associated with FeLV helper viruses
Environmental carcinogens Ultraviolet light
 
Industrial pollutants:
  • Asbestos
  • Air pollution
  • Other

Inhaled carcinogens

Squamous cell carcinoma of the pinna in white cats
 
 
Mesothelioma in dogs
Tonsillar carcinoma in dogs
?Bladder cancer in dogs
?Intranasal tumours in dogs
Post-trauma Osteosarcoma At old fracture sites in dogs
Inorganic salts Osteosarcoma - often mid-shaft At fracture sites (dogs) in which metallic internal fixators ahve been left in situ for long periods of time
Radiation
X-ray
Radioactivity
Various carcinomas