My youngest brother has been reading â€œhealthy eatingâ€ books, and was telling me that wild animals donâ€™t get cancer. He wasnâ€™t content with my correction and wanted some evidence. Fair enough. Looking around online, I found a few references and was reminded of the Laetrile nonsense.
Laetrile was a quack cancer cure popular in the 70â€™s. The tout was that sharks donâ€™t get cancer, and that taking pills made from ground up shark cartilage would cure cancer. This paragraph give a summary of the Laetrile cure fad:
The reference to the Registry of Tumors in Lower Animals sounds intriguing so I looked it up. The collection is searchable online after registering, and Iâ€™ve included a link. The Registry includes many cases of cancer in wild animals.
Looking around a bit more, I find someone else has considerately done a search of the literature, and posted abstracts. Iâ€™ve includes them below (lost track of the original source). These reports come from journals indexed by Pubmed which indexes biomedical journals, so papers in ecological or field biology journals would be missed. As you can see, there are many reports describing cancer in wild animals. The list is long, but skimming shows that tumors in wild animals have been observed many times.
Next up, Iâ€™ll look into the notion youâ€™ve gotten that microwaving your food makes it dangerous to eat.
Cesk Patol 1996 May;32(2):78-83
[Tumors in wildlife].
[Article in Czech]
Karpenko A, Bukovjan K.
Oddeleni patologie SZZ, Benesov u Prahy.
Wild animal tumours have not been much studied yet. Authors found six
mostly benign cases in Czech Republic in checking hunts between the years
1988 and 1993: Mature differentiated ovarian teratoma and apocrine skin
adenoma in field hare, intraductal mammary papillomatosis in a roe,
complex odontoma and pleomorphic mammary carcinoma (single malignancy in
the group) in fox. A soft tissue tumour in a fallow-buckâ€™s neck could not
be histogenetically classified. A high structural equivalence of animal
and human tumours allows using ICD-O classification as a whole.
PMID: 9560906 [PubMed – indexed for MEDLINE]
J Vet Med Sci 1997 Aug;59(8):703-6
Spontaneous gastric carcinoid tumors in the striped field mouse (Apodemus
Oh SW, Chae C, Jang D.
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul
National University, Suwon, Kyounggi-Do, Republic of Korea.
Gastric carcinoid tumors were found in seven of 135 striped field mice
(Apodemus agrarius) by routine histopathologic examination. All these
carcinoids occurred in mature striped field mice aged 72-100 weeks. Six
animals were females and only one was male. Only two of seven tumors were
detectable by gross examination. Grossly, tumors were located in the
fundus of the glandular stomach. All seven tumors were microscopically
single in the stomach and two mice exhibited extragastric metastasis.
Tumors from all the mice were characterized by densely packed sheets of
round to polygonal cells, subdivided into packets by a fine fibrovascular
stroma. The cytoplasm of all tumor cells from all the mice contained
argyrophil granules when stained by Grimelius and Sevier-Munger silver
procedures. All seven mice with gastric carcinoids exhibited positive
immunoreactivity to neuron specific enolase. Psammoma bodies,
concentrically laminated microcalcification, were characteristic findings
in gastric carcinoids from five mice. There were also a concomitant and
independent hepatocellular adenoma in one case and hepatocellular
carcinoma in two cases. The present cases provide the first description
of spontaneous gastric carcinoid tumors in the striped field mice.
PMID: 9300368 [PubMed – indexed for MEDLINE]
Leukemia 1997 Apr;11 Suppl 3:170-1
Plasmacytoid leukemia of chinook salmon.
Kent ML, Eaton WD, Casey JW.
Department of Fisheries and Oceans, Pacific Biological Station, Nanaimo,
Plasmacytoid leukemia is a common disease of seawater pen-reared chinook
salmon (Oncorhynchus tshawytscha) in British Columbia, Canada, but has
also been detected in wild salmon, in freshwater-reared salmon in United
States, and in salmon from netpens in Chile. The disease can be
transmitted under laboratory conditions, and is associated with a
retrovirus, the salmon leukemia virus. However, the proliferating
plasmablasts are often infected with the microsporean Enterocytozoon
salmonis, which may be an important co-factor in the disease.
PMID: 9209333 [PubMed – indexed for MEDLINE]
Pathol Int 1996 Dec;46(12):919-32
Mouse mammary tumor virus and mammary tumorigenesis in wild mice.
Nara Prefectural Institute of Public Health, Japan.
The current knowledge of the distribution of the mouse mammary tumor
virus (MMTV) proviral genomes and the mechanism of mammary tumorigenesis
by MMTV in mice, with the main emphasis on Asian feral mice, is reviewed.
The relevant earlier discoveries on the mode of MMTV transmission are
summarized to provide an outline of the biology of MMTV. Finally, the
viral etiology of human breast cancer will be discussed.
PMID: 9110343 [PubMed – indexed for MEDLINE]
Adv Neurol 1991;56:473-9
Retroviral leukemia and lower motor neuron disease in wild mice: natural
history, pathogenesis, and genetic resistance.
Department of Pathology, School of Medicine, University of California, Davis
PMID: 1649545 [PubMed – indexed for MEDLINE]
J Wildl Dis 1985 Oct;21(4):386-90
Diseases diagnosed in wild turkeys (Meleagris gallopavo) of the southeastern
Davidson WR, Nettles VF, Couvillion CE, Howerth EW.
Diagnostic findings are presented on 139 sick or dead wild turkeys
examined during the period 1972 through 1984. Turkeys originated from
eight southeastern states (Alabama, Arkansas, Florida, Georgia, South
Carolina, Tennessee, Virginia, West Virginia) and included 31 turkeys
categorized as capture-related mortalities and 108 turkeys categorized as
natural mortalities. Frequent diagnoses (greater than or equal to 10% of
case accessions) in the natural mortality group were trauma, avian pox,
and histomoniasis. Less frequent diagnoses (less than or equal to 4% of
case accessions) included malnutrition/environmental stress syndrome,
coligranuloma-like condition, crop impaction, bumblefoot, organophosphate
toxicosis, infectious sinusitis, a lympho-proliferative disease,
salmonellosis, aspergillosis, toxoplasmosis, crop trichomoniasis, and
PMID: 4078973 [PubMed – indexed for MEDLINE]
Acta Vet Scand 1985;26(1):61-71
Leukaemic neoplasia in free-living mammals in Denmark.
Elvestad K, Henriques UV.
PMID: 3839967 [PubMed – indexed for MEDLINE]
Int J Cancer 1981 Aug 15;28(2):241-7
Natural killer cell activity in a population of leukemia-prone wild mice
Scott JL, Pal BK, Rasheed S, Gardner MB.
Natural cell-mediated cytotoxicity against YAC-I targets was measured in
splenocytes from leukemia-prone wild mice trapped near Lake Casitas (LC)
in southern California. Cytotoxicity was mediated by cells that were
non-adherent to nylon wool, non-phagocytic and resistant to thy-1.2
antiserum plus complement. Natural MuLV viremia in LC mice did not impair
splenic cytotoxicity against TAC-I target cells, Cells infected with
amphotropic and ecotropic MuLV of wild mouse origin were not appreciably
lysed by LC splenic effectors. Although variable levels of cytotoxicity
were detected against TAC-1 by normal spleen cells, consistently low
levels of cytotoxicity against allogenic LC lymphoma, sarcoma and
carcinoma targets were found using the same splenocytes. These results
indicate that LC mice possess splenocytes with the characteristics of
natural killer (NK) cells as defined in inbred mice. The resistance of
LC-derived targets to lysis by LC NK cells suggests that NK cells may not
be involved in natural tumor immunosurveillance or that the development
of spontaneous tumors may involve escape from NK-mediated effector
PMID: 6274813 [PubMed – indexed for MEDLINE]
Vet Pathol 1977 Nov;14(6):539-46
Gynecologic pathology in the rhesus monkey (Macaca mulatta). II. Findings in
laboratory and free-ranging monkeys.
The most prevalent findings in reproductive tracts of 38 laboratory and
17 free-ranging Rhesus female monkeys were vaginitis, cervicitis,
metritis, pelvic endometriosis and uterine adenomyosis. Several monkeys
had cervical dysplasia and one had a serous cystadenoma. The findings in
the two groups were similar although prevalence for several diseases
differed. There was a significant relationship between the occurrence of
vaginitis, metritis, adenomyosis and endometriosis and gravidity, time
since last pregnancy, number of matings, hysterotomies, reproductive
ability and reproductive status.
PMID: 412291 [PubMed – indexed for MEDLINE]
J Wildl Dis 1999 Oct;35(4):804-7
Relating tumor score to hematology in green turtles with
fibropapillomatosis in Hawaii.
Work TM, Balazs GH.
U.S. Geological Survey, Biological Resource Division, National Wildlife
Health Center, Honolulu Field Station, Hawaii 96850, USA.
The relationship between hematologic status and severity of tumor
affliction in green turtles (Chelonia mydas) with fibropapillomatosis
(FP) was examined. During 1 wk periods in July 1997 and July 1998, we
bled 108 free-ranging green turtles from Palaâ€™au (Molokai, Hawaii, USA)
where FP is endemic. Blood was analyzed for hematocrit, estimated total
solids, total white blood cell (WBC) count and differential WBC count.
Each turtle was assigned a subjective tumor score ranging from 0 (no
visible external tumors) to 3 (heavily tumored) that indicated the
severity of FP. There was a progressive increase in monocytes and a
decrease in all other hematologic parameters except heterophils and total
numbers of white blood cells as tumor score increased. These data
indicate that tumor score can relate to physiologic status of green
turtles afflicted with FP, and that tumor score is a useful field monitor
of severity of FP in this species.
PMID: 10574546 [PubMed – indexed for MEDLINE]
J Wildl Dis 1999 Oct;35(4):753-62
Descriptive epidemiology of roe deer mortality in Sweden.
Aguirre AA, Brojer C, Morner T.
Department of Wildlife, The National Veterinary Institute, Uppsala, Sweden.
A retrospective epidemiologic study was conducted to examine causes of
mortality of 985 wild roe deer (Capreolus capreolus) submitted to the
National Veterinary Institute (SVA; Uppsala, Sweden) from January 1986 to
December 1995. Age, sex, body condition, and geographic distribution as
related to disease conditions are reported herein. The most common causes
of mortality in roe deer were trauma (19%), winter starvation (18%),
gastritis/enteritis (15%), bacterial infections (11%), parasitic
infection (11%), systemic diseases (11%), neoplasia (2%), congenital
disorders (1%), and miscellaneous causes (6%). Cause of death was not
determined in 6% of the cases. The distribution of causes of death
reported in this study differ from previous works in Sweden in that
infectious and parasitic diseases were more common than winter
starvation. The pathologic findings in studies like this do not
necessarily represent what is occurring in the natural environment, but
they do provide a good indication of distribution of diseases over time
as well as age and sex structure in relation to disease conditions.
Further research and more detailed studies are in progress to better
understand specific mortality factors as well as etiologies of certain
described diseases in roe deer in Sweden.
PMID: 10574535 [PubMed – indexed for MEDLINE]
J Zoo Wildl Med 1999 Mar;30(1):165-9
Herpesvirus-associated papillomas in koi carp (Cyprinus carpio).
Calle PP, McNamara T, Kress Y.
Wildlife Health Sciences, Wildlife Conservation Society, Bronx, New York
From January through November 1994, 32% (7/22) of koi carp (Cyprinus
carpio) maintained in indoor aquariums developed proliferative cutaneous
lesions that consisted of single to multiple 2-10-mm whitish to pink
fleshy masses usually associated with fin rays. Although scaleless koi
were more commonly affected (3/6) than were normally scaled koi (4/16),
the difference in incidence rates was not significant (chi2 text, P >
0.05). Lesions typically resolved spontaneously in 1-3 wk, occasionally
persisted for >3 mo, and recurred in several fish after 2-5 mo. Fish were
otherwise asymptomatic. Wet mount preparations from lesions were densely
cellular and consisted of hyperplastic epidermal cells of normal
morphology without parasites or inflammatory cells. Histologically,
biopsies were consistent with papillomas and were characterized by a
marked benign epidermal hyperplasia without inclusion bodies or
inflammatory infiltrate. Transmission electron microscopic examination
revealed intranuclear and intracytoplasmic herpesvirus virions. Virus
isolation attempts were unsuccessful.
PMID: 10367660 [PubMed – indexed for MEDLINE]
J Wildl Dis 1999 Apr;35(2):392-4
Adenocarcinoma of the mammary gland in a red fox from Austria.
Janovsky M, Steineck T.
Research Institute of Wildlife Ecology, University of Veterinary Medicine,
A mammary gland adenocarcinoma was diagnosed in an adult red fox (Vulpes
vulpes) which was shot in Austria in August 1995. Metastases were found
in the kidneys and liver. This is the first reported case of an
adenocarcinoma in a fox, and lack of mammary gland carcinoma in this
species may be age related.
PMID: 10231770 [PubMed – indexed for MEDLINE]