PLACENTAL MAMMALS
11.1 Bats
Neoplasia in bats is rare (3 benign and 10 malignant neoplasms identified in six Australian bat species) (Table 18.18). Three cases each of lymphosarcoma and fibrosarcoma have been documented.
No reports of attempted treatment were identified.11.2 Rodents
A range of neoplasms have been documented in Australian rodents (Tables 18.19 and 18.20). Of 58 identified neoplasms, 18 (31.0%) were lymphoid malignancies, making these the most frequently occurring neoplasm in Australian rodents. There are an enormous range of native rodents, of which several species are overrepresented. This should be considered a bias of species being submitted to the ARWH (i.e. species common in zoological populations that report to the ARWH), rather than a particular species predilection to neoplasia.
Reports of treatment of any neoplasia in Australian rodents are rare. A water rat (Hydromys chrysogaster) had a trichoblastoma surgically excised, which was effectively curative as the animal remained free of this neoplasm until its death 2 yr later (ARWH 2018 case no. 5617.1). At its death, this rat did have multiple unrelated neoplasms, including metastatic phaeochromocytoma, a vaginal leiomyosarcoma and a thyroid adenoma.
Table 18.17. Neoplasms documented in the short-beaked echidna (Tachyglossus aculeatus)
| Benign | Malignant |
| Fibroma: beak 3 Chondroma: humeral 1c Adenoma: thyroid 5 | Lymphosarcoma: multicentric,1b splenic,1a,2 myocardial 3 Leukaemia: lymphoid 4 Leiomyosarcoma: pericloacal3 Soft tissue sarcoma: beak6 |
1ARWH 2018 case nos: a6071.1; bB0083; c839.4; 2Gentz etal.
2009; 3Whittington 1993; 4Booth 1999; 5Ladds 2009; 6Robey etal. 2018.
Table 18.18. Neoplasms documented in bats
Benign
| Leiomyoma: uterine | Gould's long-eared bat (Nyctophilus gouldi)1a |
| Papilloma: wing | Gould's wattled bat (Chalinolobus gouldii)2 |
| Fibropapilloma | Grey-headed flying-fox (Pteropus poliocephalus)2 |
Malignant
| Carcinoma | Hepatocellular: little red flying-fox (P. scapulatus)∙1b Primary unknown: grey-headed flying-fox2 |
| Fibrosarcoma | Patagial: grey-headed flying-fox;1c Abdominal: lesser long-eared bat (N. geoffroyi)∙2 Subcutaneous: greyheaded flying-fox2 |
| Lymphosarcoma | Multicentric: spectacled flying-fox (P. conspicillatus)1e grey-headed flying-fox2; Leukaemic: spectacled flying fox1d |
| Mesothelioma | Grey-headed flying-fox3 |
| Teratoma: ovarian | Spectacled flying-fox1f |
1ARWH 2018 case nos a6884.1; b10170.1; c11462.1; d6301.3; e6301.2; f6301.1; 2Ladds 2009; 3Jakob-Hoff and Shaw 2006
Table 18.19. Benign neoplasms in rodents
| Adenoma | Hepatic (hepatoma): spinifex hopping mouse (Notomys a lexis'),1 grassland melomys (Melomys burtoni), black-footed tree-rat (Mesembriomys gouldii)∙2 Thyroid: water rat (Hydromys chrysogaster)1b |
| Fibroma | Spinifex hopping mouse2 |
| Haemangioma | Spinifex hopping mouse2 |
| Lipomatosis: dermal | Spinifex hopping mouse1c |
| Phaeochromocytoma | Water rat1d |
| Thymoma | Stick-nest rat (Leporilluss pp.)2 |
| Trichoblastoma: cutaneous | Water rat1b |
| 1ARWH 2018 case nos a7188.1; b5617.1; c7321.1; | d2035.1; 2Ladds 2009 |
If a rodent is considered an appropriate candidate for treatment, then guidance and protocols as per those described in domestic rodents, particularly rats and mice, could reasonably be used.
11.3 Dingo
There are a few reports of neoplasia in the dingo (Canis familiaris) (Table 18.21). It is likely that predisposition to neoplastic disease in the dingo is similar to that of domestic dogs, though there is not enough data on dingoes to definitively compare. Principles of diagnosis and treatment can reasonably follow protocols described for domestic dogs.
A handful of cases of surgically treated neoplasms in dingoes are reported, all with good outcomes based on lack of evidence of recurrence at eventual necropsy. These included perianal adenocarcinoma, cutaneous basal cell tumour, mucocutaneous melanoma and SC lipoma (ARWH 2018 case nos 3583.1; 3583.3; 1600.2; and 4381.1,
Table 18.20. Malignant neoplasms in rodents
| Adenocarcinoma | Abdominal: stick-nest rat (unspecified);1 Biliary: Mitchell's hopping mouse (Notomys mitchellii)∙1 Colonic: spinifex hopping mouse (N. alexis);2a Pulmonary: grassland melomys (Melomys burtoni);1 Ovarian: plains mouse (Pseudomys australis);1 Shoulder: pale field rat (Rattus tunneyi) |
| Carcinoma | Abdominal: black-footed tree-rat (Mesembriomys gouldii)2 Bronchioalveolar: plains mouse;2c Bronchiolar: grassland Melomys,1 plains mouse;2d Hepatocellular: spinifex hopping mouse;2e Mammary: 2 ? bush rat (R. fuscipes)f Thyroid (C-cell): plains mouse2h |
| Chordoma | Water rat (Hydromys chrysogaster)2 |
| Fibrosarcoma | 2 ? grassland melomys1 |
| Granular cell tumour | Spinifex hopping mouse2j |
| Granulosa-theca cell tumour | Spinifex hopping mouse2k |
| Haemangiosarcoma: hepatic | Plains mouse2l |
| Leiomyosarcoma: vaginal | Water rat2i |
| Leukaemia | 3 ? spinifex hopping mouse2m,n,cι |
| Liposarcoma | Ash-grey mouse (P. albocinereus) |
| Lymphosarcoma | Multicentric: 3 ? plains mouse,2r,s,t ash-grey mouse,1 7 ? spinifex hopping mouse;2u,v,w,x,y,z,aa Thymic: plains mouse,2bb spinifex hopping mouse,1 black-footed tree-rat;2cc Mediastinal: 2 ? water rat;2dd,ee Conjunctival: black-footed tree rat;2p Type unspecified: spinifex hopping mouse2q |
| Phaeochromocytoma | Water rat2i |
| Rhabdomyosarcoma | Spinifex hopping mouse1 |
| Sarcoma | Hepatopancreatic: stick-nest rat (unspecified);1 Soft-tissue: 2 ? spinifex hopping mouse2m,ff |
1Ladds 2009; 2ARWH 2018 case nos a9477.1; b2404.1; c6938.1; d4736.1; e10644.1; f9331.1; g9947.1; h6622.1; i5617.2; j7985.1; k9159.1; l3497.1; m6337.1; n6973.1; o5915.1; p7970.1; q6868.1; r8678.5; s9777.1; t10285.1; u3129.1; v7589.1; w7847.1; x9000.1; y167.1; z3146.1; aa5837.1; bb8678.1; cc2404.1; dd1338.1; ee6103.1; ff7698.1
Table 18.21. Neoplasms in dingoes (Canis familiaris)
| Benign | Malignant |
| Adenoma: bronchial1; 2 ? sebaceous2a,b Epulis: fibromatous (gingival)2c Leiomyoma: gastric2d Lipoma: subcutaneous2a Thymoma3 | Adenocarcinoma: pancreatic4, perianal2e Basal cell tumour: cutaneous2e Lymphosarcoma4 Melanoma: oral mucocutaneous junction2f Sarcoma: soft-tissue (elbow)2 g Squamous cell carcinoma: oral2h |
1Lombard and Witte 1959; 2ARWH 2018 case nos a4381.1; b5760.1; cK0263; d8812.1; e3583.3; f1600.2; g6864.1; h3583.2; 3Ladds 2009; 4Hulst 2008
respectively).
An oral SCC was successfully treated with hemimandiblectomy (ARWH 2018 case no. 3583.2).11.3.1 Canine transmissible venereal tumour
Canine transmissible venereal tumour (CTVT) is a contagious neoplasm that affects the external genitalia, primarily of stray dogs in subtropical and tropical regions globally (Strakova and Murchison 2014). In Australia it is mainly found in stray or camp domestic dogs in the NT and WA (Strakova and Murchison 2014). Free-ranging canids are experimentally susceptible to CTVT (Ganguly et al. 2016). Naturally occurring CTVT has not been formally reported in the dingo; however, a dingo-cross dog was diagnosed and successfully treated for CTVT in Box Hill, Vic. (Victorian Animal Cancer Care 2017). This dog was originally from a remote camp in Coober Pedy, SA. Given the distribution of CTVT in Australia, and the lifestyle and contact between remote camp or stray dogs
Table 18.22. Neoplasms documented in pinnipeds
| Benign | |
| Adenoma | Adrenal: southern elephant seal (Mirounga Ieonina);1 Hepatic: Australian fur seal (Arctocephalus pusillus),1 long-nosed fur seal (Arctophoca forsteri)2 Pituitary: subantarctic fur seal (Arctophoca tropicalis)2 Thyroid (bilateral, multiple): 2 ? Australian fur seal2c,d |
| Epulis: fibromatous (multiple) | Leopard seal (Hydrurga leptonyx)3 |
| Leiomyoma | Intestinal: Australian fur seal;1 Uterine (multiple): 2 ? Australian fur seal2c,e |
| Papillomatosis: oral | Long-nosed fur seal2f |
| Phaeochromocytoma: bilateral | Australian fur seal2e |
| Malignant | |
| Adenocarcinoma | Hepatic: Australian fur seal;1 Renal (anaplastic): long-nosed fur seal2 g |
| Astrocytoma | Australian sea-lion (Neophoca cinerea)2h |
| Carcinoma: basal cell | Long-nosed fur seal1 |
| Epulis: anaplastic | Australian fur seal2i |
| Granulosa cell tumour | Australian fur seal,2d southern elephant seal4 |
| Leiomyosarcoma: metastatic | Fur seal (unspecified)5 |
| Lymphosarcoma: multicentric | Long-nosed fur seal,2a Australian fur seal1 |
| Melanoma: metastatic | Australian fur seal1 |
| Neuroblastoma | Long-nosed fur seal6 |
| Oligodendroglioma | Long-nosed fur seal2j |
| Osteosarcoma: carpal | Long-nosed fur seal2k |
| Soft-tissue sarcoma: axillary | Australian fur seal2d |
| Seminoma | Australian sea-lion2h |
1Ladds 2009; 2ARWH 2018 case nos a8227.1; b6528.1; c3465.1; d4820.1; e5181.1; f3254.2; g4308.1; h9201.1; i2335.2; j8180.1; k31.1; 3Gales 1984; 4Mawdesley-Thomas 1971; 5Durham and Queale 1995; 6Forshaw 2006
and dingoes, extension of CTVT to free-ranging or managed dingoes is possible if not probable.
Treatment of CTVT can be multimodal, though chemotherapy with vincristine sulfate is particularly effective, with most cases cured with 3-wk IV doses (Amber and Henderson 1990). Surgical management is often limited, as there is a risk of recurrence, seeding of neoplastic cells and limitations imposed by the anatomical location of the tumours (Ganguly et al. 2016).11.4 Pinnipeds
Neoplasms in Australian pinniped species are less frequent than those described in the Northern Hemisphere (Ladds 2009). The majority of neoplasms documented in Australian pinnipeds are in aged, managed animals (Ladds 2009; ARWH 2018). Oral papillomatosis of suspected viral aetiology has been noted in a long-nosed fur seal (Arctophoca forsteri) (ARWH 2018 case no. 3254.2). Two cases each of multiple bilateral thyroid adenoma and multiple uterine leiomyoma have been seen in Australian fur seals (Arctocephalus pusillus) (ARWH 2018 case nos 3465.1; 4820.1; 5181.1). Intracerebral malignancies comprised 33% (3/15) of malignancies reported in pinnipeds (astrocytoma, oligodendroma, and neuroblastoma) (Table 18.22).
11.5 Cetaceans
Neoplasia in free-ranging cetaceans in Australian waters is rare (Blyde and Vogelnest 2008; Ladds 2009). Lymphoid malignancies (leukaemia and lymphosarcoma) have been diagnosed in two free-ranging, stranded common bottlenosed dolphins (Tursiops truncatus) (Robertson 1994; Cowan 2003). An incidental focal hepatic myeloma was noted in a stranded bottlenose dolphin (species unspecified) in Tas. (Ladds 2009). Multifocal abdominal leiomyomas were reported in an adult female common dolphin (Delphinus delphis) in SA waters (Tomo and Kemper 2022). There are no known reports of neoplasia in free- ranging whales in Australian waters.
Review of 150 necropsies in the ARWH (1998-2017), representing 19 species of free-ranging cetaceans, found no neoplasia (ARWH 2018).
Epidermal dysplasia and SCC of the orogenital mucosa is reported in free-ranging dolphins in North American waters and lesions have been associated with papillomavirus infection and anthropogenic water contaminants (Bossart et al. 2005, 2015). Pre-neoplastic epidermal dysplasia was documented in a single free-ranging Risso’s dolphin (Grampus griseus) from Australian waters, with suspected (though unconfirmed) underlying papillomavirus infection (ARWH 2018 case no. 10087.1).
Dolphins in oceanariums in Australia have been diagnosed with the following neoplasms: lymphosarcoma (n = 2), haemangiosarcoma and SCC (Blyde and Vogelnest 2008; Blyde and Sandy 2016). The two cases of multicentric B-cell lymphosarcoma were in a mother and offspring common bottle-nosed dolphins. Electron microscopy did not detect retroviral particles in either case (Blyde and Sandy 2016). Chemotherapeutic treatment of palatine SCC in a 38-yr-old Indo-Pacific bottle-nosed dolphin (T. aduncus) with piroxicam and doxycycline was successful at markedly reducing tumour size and the lesion remains stable (March et al. 2016).
11.6 Dugongs
There are no known reports of neoplasia in the dugong (Dugong dugon).