In Cancer Prevalence and Etiology in Wild and Captive Animals Madsen, Arnal, Vittecoq et al it is stated that:
"Wildlife cancer statistics are, however, highly scattered in the scientific literature and hence challenging to access. Moreover, tumors in wildlife are most commonly detected during postmortem examination and therefore hard to confirm without histopathological examinations. However, even such analyses can be inaccurate because of high levels of autolysis (organ disintegration) (McAloose and Newton, 2009).
" In addition, individuals harboring tumors often display a decrease in body condition frequently resulting in higher levels of parasite/pathogen infections and concomitant increased levels in morbidity and mortality (Vittecoq et al., 2013) "
The paper lists only one known red fox case: Vulpes v. pennsylvanicus American red fox Adenoma Ratcliffe (1933)
To this I can add two British cases -one from the Bristol Fox Necropsy Study:
029 Dog 4.80kg Old Adult (which means over 5yrs) Poor/Emaciated Severe necropathy and lymphoma (cancer)
The second is a new case and only occurred yesterday (Sunday 31 05 2026): a fox (SH001 31 05 26) was in a collapsed state and my colleague, LM, attempted to secure it to take to a vet, however, as in such cases, the fox used a burst of energy and started swimming toward an island in a pond (mini lake). The fox was being unsuccessful and so LMs daughter swan out and retrieved it where it was taken care of before going to a vet (not LMs regular one).
The vet reported that the fox died while under anaesthesia (we have questions here) but the results of the examination and X-rays was that the it had broken canine teeth, pelvic swelling and osteosarcoma.
Osteosarcoma is an aggressive type of primary bone cancer that typically affects children, teens, and young adults. It most commonly develops in the long bones near the knee or shoulder. Standard treatment combines chemotherapy and surgery to remove the tumor and save the affected limb. With wildlife and foxes in particular veterinary care is in the hit-or-miss stage and based on whether the vet decides it is too costly, not worthwhile, etc. Wildlife has no National Health Service.
Luckily LM maintains video observation of foxes in the area so was able to give a brief background report on this fox:
"I've watched the whole video of her at normal speed on Friday night. She was moving normally, but she sat down for 2 mins which she hadn't done before , her ears were slightly not upright . She didn't come Saturday night, I think she got as far as my side of the pond . Where I found her Sunday am at 0630.
"So the onset was acute not degenerative. She has no injuries or bite marks. Vixen 4.52 kg and full teats -as she thawed out the teats were squeezed and milk emerged.
"She will be going for toxicology and Histopathy."
Histopathology is the microscopic examination of tissue to study the manifestations of disease. It is the gold standard for diagnosing cancers, inflammatory conditions, and infectious diseases. By analyzing cellular structure, pathologists determine the exact nature of an abnormality, helping clinicians decide on the best treatment.)
"Just foxes" still applies in wildlife work and 99% of UK fox rescues/wildlife hospitals tell me that they do not submit foxes for PMs so it is very possible -very likely in fact- that we miss a great deal that might push our knowledge on fox diseases and illnesses and treatments forward.
That we now have two UK fox cancer cases is sad but worthy of note.
Any updates will follow as received.
