Marsupials Flashcards

Question

What are some common neoplasias affecting marsupials? (excluding devil facial tumor disease) What species is predisposed to lymphoma? What infectious disease is associated with it? Descirbe its behavior. What cell type is most common? What facial neoplasia is common in koalas? Mesothelioma is common in what species? Soft tissue sarcomas have been associated with what procedures? What species?

Answer 1

Neoplasia * Lymphosarcoma o Can occur in any marsupial, but most commonly occurs in koalas o Greater expression of koala retroviral (KoRV) is associated with lymphosarcoma but unclear if causative or secondary effect ▪ 100% of koalas endogenously infected with KoRV in most of koala’s natural range, so cause of lymphosarcoma likely multifactorial o Can progress rapidly and up to 63% can become leukemic o T cell most common ● Osteochondroma o Koalas—most commonly craniofacial originating from nasal cavity and sinuses ● Mesothelioma o Koalas most common o Serosal thickening and diffuse nodules on the serosal surface extending into the musculature o Usually in the abdominal cavity but also in the pericardium, pelvic cavity, and scrotal tunics ● Soft Tissue Sarcomas o Including myxosarcoma, fibrosarc, and osteosarc have been described in feathertail gliders and a koala in association with a SQ microchip/transponder tag o Typically 2-3 years after placement

Answer 2

● **Macropod herpesvirus 1 (MaHV-1)** o Alphaherpesvirus o Sudden death and rhinitis, conjunctivitis, pneumonia, cloacal ulceration, and variable splenic, pulmonic, and hepatic necrosis with intranuclear inclusion bodies in captive parma wallabies ● **MaHV-3** o Gammaherpesvirus o Respiratory disease in a group of free ranging eastern gray kangaroos ● **MaHV-4** o Alphaherpesvirus o Respiratory and neuro disease in a free living eastern gray kangaroo ● Cytomegalic inclusions without associated inflammation or apparent impact have been described in the prostate of antechinus and phascogale and renal tubular epithelium of bettongs, platypus, and pygmy possums o Thought to be herpesviral in morphology but no viral particles observed yet

Answer 3

● Poxviral lesions o Most commonly reported in macropods o Typical exophytic, hyperkeratotic cutaneous lesions with eosinophilic inclusion bodies ● Bandicoot papillomatosis and carcinomatosis virus 1 (BPCV 1) and BPCV2 o Associated with papillomatous and carcinomatous lesions in wester barred and southern brown bandicoot o This disease is an impediment to species recovery efforts o The viruses are genetically intermediate between papillomaviridae and polyomaviridae o Induce a spectrum of cutaneous and mucocutaneous lesions o Lesions classified as epithelial hyperplasia, carcinoma in situ, or SCC o Carcinomatous lesions can metastasize

Answer 4

RNA viruses ● Arboviruses o Many endemic to Australia that cause dz in humans but marsupials are subclinical reservoirs or amplification hosts o Examples of these viruses are Ross River Virus, Barmah Forest Virus, Murray Valley Encephalitis Virus and the Kunjan strain of WNV Wobbly Possum disease o Fatal disease of brushtail possums in NZ o Caused by a novel nidovirus o Nonsuppurative encephalitis and myocarditis o Most lesions in liver, spleen, heart, brain, meninges, and kidneys o Lymphocytic and plasma cell infiltrates in these organs

Answer 5

**Fowler 7 Ch 51 - Viral Chorioretinitis of Kangaroos** * 1990 – Many blind kangaroos observed along the Darling River in webersn New South Wales between April and July 1994 * March thru June 1995- the disease reappeared and extended into NW Victoria and SE South Australia * Dec 1995 thru April 1996- kangaroos in southern Western Australia also affected * Outbreak of blindness in NW Victoria in 1975 retrospectively confirmed as viral chorioretinitis by PCR **Natural Hosts:** **· Most common in western grey kangaroos (*Macropus fulginosis*)** · Also detected in eastern grey kangaroos (*M. giganteus*), red kangaroos (*M. rufa*), and euros (*M. robustus*) · Captive red-necked wallabies (*M. rufogriseus*) and swamp wallabies (*Wallabia bicolour*) in affected areas had positive serologic results to two obriviruses, but no clinical signs. · Sheep from affected areas also seropositive, but no clinical signs **Cause:** · **Two orbiviruses implicated: Wallal and Warrengo viruses** **Epidemiology** · **Transmitted by biting midges (*Culicoides austropalpalis*, *C. dycei*, and *C. marksi*)** · Other insects, especially mosquitoes, no not appear to be involved · *C. austropalpalis* is known to prefer feeding on bird, avian involvement in maintenance and transmission of virus in nature is unclear. · 1995-50% to 85% of kangaroos tested in affected area seropositive to both viruses o Associated prevalence of blindness ranged from less than 5% to 50% · Animals are viremic for less than 2 weeks, within several weeks of first infection, and weeks to months before clinical signs appear. · No evidence of direct transmission from kangaroo to kangaroo **Clinical Signs and Diagnosis:** **· Blind, altered gait, shorter and higher hops, hopping in circles, star gazing** **· Any deaths appear to be secondary to blindness (malnutrition, injury, etc)** · Few external signs of eye disease o Some have small focal retinal lesions with little or no clinical manifestations o Many apparently normal kangaroos have lesions detected on pathology o Changes in eye reflectivity when spotlighted at night can indicate early change o Some individuals have accompanying anterior uveitis § Pupils may remain dilated and animal doesn’t squint in bright sunlight · Increased rectal temp not a reliable indicator of viremia * Ophthalmoscopic Examination: * Normal fundus * Has fine, short retinal vessels emanating from the optic disc * Background color is a bland reddish brown (choroidal vasculature) * \*\*No Tapetum\*\* * Some have normal variation of pale area surrounding the optic disc * **Acute lesions of active retinal and/or choroidal inflammation** * **Progressive focal to extensive pale areas of the retina** * **Some acutely affected animals may have anterior uneitis** * **Chronic retinal lesions are hyperreflective, pigmented, and nonprogressive** * Laboratory Results: * Histopathology: * **Eyes should be collected into Bouin’s fixative within15 minutes of death** * One eye fixed whole, the other opened for virus isolation samples * 10% formalin may give reasonable results * Brain and optic nerve should also be collected in formalin * **Immunohistochemistry:** * **Strong positives for only Wallal virus seen in degenerate retinas of acute experimental cases.** * **Reaction was confined to the retina and absent from inflamed choroid, degenerate optic nerve, and all other tissues** * Electron Microscopy: * 1-mm cutes of retina and underlying choroid should be collected with 15 minutes of death, fixed for 4 hours in 2.5% glutaraldehyde in phosphate buffered saline pH 7.5 (PBS). * Icosahedral virus particles 65nm in diameter are associated with disrupted and degenerative photoreceptor cells and macrophages of affected retinas. * Virus inclusion bodies and cytoplasmic virus-specific 30-nm diameter tubules may be seen in infected cultured cells. * \*\*Findings are characteristic of the genus Orbivirus\*\* can be confirmed with immunogold labeling. * Virus Isolation: * Wallal and Warrego viruses isolated from acute, but not chronic, cases in BHK-21 cells, in primary retinal cell cultures, and in joey kidney and lung cells. * **PCR:** * **PCR developed for variant and reference Wallal and Warrego viruses** * **Can be used on fresh and fixed tissue** * **Variant Wallal virus detected in eyes and brain collected at necropsy of affected kangaroos with eye lesions** * **Warrego virus also detected in some wild animals** * **Test can also be applied to insect samples (detected in 3 species of midges)** * Serology: * Seroconversion is widespread during outbreaks * Hematology and Serum Biochemistry: * No detectable changes on routine biochemistry attributable to this infection * Further Diagnostic Considerations: * Histopathologic lesions are pathognomonic in animals euthanized due to blindness during outbreaks in endemic areas of Australia. * For isolated cases with similar pathology, PCR or immunoperoxidase testing should be used as confirmatory tests. * Pathology and Pathogenesis: * Principle lesions: retinitis and/or retinal degeneration and uveitis * Retinal lesions vary in extent from small segmental lesions to involving the whole retina * Acute cases: active retinal degeneration, necrotic retinal cells, neutrophils, gitter cells, protin rich exudates (Fig 51-1, pp. 392) * Chronic cases: (\> 1 month duration) segmental to extensive atrophic retinal remnants and few inflammatory cells (Fig 51-3, pp. 393) * Uveitis: Infiltration with mononuclear cells, including prominent plasma cells, most severe in the choroid overlying the affected retina. * Wallerian degeneration – secondary change resulting from loss of gangion cells from the retina, seen in optic nerves in acute cases, extends to optic tracts in chronic cases. * Mild multifocal nonsuppurative encephalitis in some cases * Eye lesions may be immunologically mediated- eye normally contains no lymphocytes and no antigen-processing macrophages. * Is assumed that the initial infection of the eye is coincident with, or soon after the detectable viremia. * Lymphocytes activated in the spleen in response to leakage of foreign antigen from the eye * Takes at least one week to reach the eye to respond to antigenic stimuli leading to uveitis. * Fundic changes not seen for at least another 2 weeks, suggests an immunologic pathogenesis for retinal damage. * Macropod eye anatomy: the retina is more dependent on choroidal blood supply than in eutherian mammals, might be predisposed to retinal damage secondary to choroidal inflammation. * Dual infection with both Wallal virus and Warrego virus may be necessary for serious eye lesions to occur. * Sequential or dual infections and the enhancement of infection/severity of clinical disease by antibody investigated for dengue fever and Murray Valley encephalitis. * Further studies needed to clarify the pathogenesis of viral chorioretinitis in macropods. **Treatment, Prevention, and Control:** · Local or systemic corticosteroid treatment may be helpful to reduce retinal damage in acute cases, assuming an immunologic pathogenesis, but is unproven. · Currently no treatment is practical and retinal damage is permanent · Not directly contagious, so unlikely to occur outside endemic areas of Australia · Period of viremia is brief, and no carrier state is known, so risk of transport of infected macropods, except from affected areas during an outbreak, is minimal. · A national arbovirus monitoring program in Australia plots the extent of arboviral spread on an annual basis to help guide decisions on risks of moving animals. · A one-month quarantine of animals imported in insect-proof enclosures from endemic areas would remove any risk of introduction. Orbiviral blindness caused by Wallal and/or Arrego viruses - Terio ZP o Predominantly in kangaroos, also in wallaroos o Outbreaks up to 30% of animals in a group effected Sudden blindness, chorioretinitis and often encephalitis

Answer 6

● Tammar wallaby (Macropus eugenii) sudden death syndrome o Only reported in zoos and research colonies o Associated with an orbivirus of the Eubenagee serogroup o Lethargy, head drop, ataxia, muscle tremors, death o Gross findings: marked diffuse pulmonary and hepatic congestion and SQ edema with petechiae in the extremities o Lymphocytolysis in lymphoid germinal centers is a consistent finding o Multifocal hemorrhage also common

Answer 7

● Koala retrovirus A (KoRV A) o Gamma retrovirus o Widespread in australia, 100% prevalence in queensland and new south wales where it is endogenous (inherited in the germ line) o Variable prevalence elsewhere o Possible etiologic agent of lymphoma and other lymphoid disorders but also likely multifactorial o 3 subtypes (A, B, C) o KoRVA is the only endogenous one, others are exogenous o Some evidence to suggest an association between KoRVB infection and lymphoma or death of pouch young

Answer 8

● Necrobacillosis (lumpy jaw) o Common in macropods o Fusobacterium necrophorum most common but nocardia and others can also be involved o Predisposing factors include overcrowding, stress, abrasive or soft forage, facial trauma, and GI parasites o Edematous or bony swelling in the maxillary or mandibular area, usual with abscessation o Hematogenous spread can cause visceral lesions

Answer 9

● Tyzzers disease (Clostridium piliforme) o Reported in several marsupial species o Mostly in young animals o Liver and heart affected most commonly ● Tetanus (C. tetani) o Macropods, similar presetation as in other mammals ● C perfringens o Enterotoxemia in young kangaroos

Answer 10

● Mycobacteria o Marsupials are highly susceptible o Affected by various species including M. bovis, M ulcerans, M tuberculosis, M paratuberculosis, M avium, and others o In New Zealand brushtail possums are a big reservoir for M bovis o Reasons for susceptibility are unclear but likely related to their inflammatory response o Lesions typically granulomatous or pyogranulomatous with giant cells often seen o M ulcerans is the causative agent of Bairnsdale, Buruli, or Daintree ulcer in humans and can cause ulcerative dermatitis in koalas and brushtail possums which are proposed reservoirs for this pathogen

Answer 11

● Chlamydiosis o Most common infectious disease of koalas o C pecorum most common but can also get C pneumoniae o C pecorum present in almost all free ranging koala populations, variable prevalence o Transmitted sexually and likely during birth via monocytes in milk or ingestion of maternal cecal feces (pap-feeding) o Majority of tissue damage caused by host’s response rather than by cell lysis from chlamydial replication o Pyometra, metritis, cystitis, pyelonephritis are common o Ovarian bursa may fill with fluid to form multiloculated cysts o In males prostatitis and rarely orchitis have been described o Hydroureter and hydronephrosis are common sequelae of fibrotic cystitis and ascending pyelonephritis o Ocular lesions—from mild conjunctival hyperemia and edema to epithelial and lymphoid hyperplasia, thickened cauliflower-like nictitans o Keratitis and blindness common o Occasionally pneumonia can be seen o Histology – villous epithelia hypertrophy and hyperplasia and squamous metaplasia o Diagnosis by PCR or IHC

Answer 12

● Bordetella bronchiseptica o Can cause fatal outbreaks of respiratory disease in captive koalas o Considered an opportunistic pathogen o Causes suppurative bronchopneumonia o Pasteurella multocida can also cause opportunistic bronchopneumonia or septicemia from cat bite wounds

Answer 13

Fungi ● Cryptococcosis (cryptococcus gattii) o Koalas affected o Saprophytic yeast, associated with a wide range of eucalyptus species o Nasal mucosa of koalas commonly colonized without lesions o Disease is rare but can cause respiratory disease (lower more common than upper) o Dissemination to CNS common as well as invasion into local tissues o Can cause neutrophilic to granulomatous inflammation

Answer 14

Metazoa ● Angiostrongylus cantonensis o Rat lungworm, reported in several marsupials o Infection via ingestion of terrestrial or aquatic gastropod o Usually pulmonary infection but can cause ascending paralysis via larval migrans ● Echinococcus granulosus (hydatid) o Many marsupials are intermediate hosts of this worm o Hydatid cysts occur in lung and thoracic cavity rather than liver ● Cloacinid nematodes o Occur in the sacculated forestomachs of macropods o Majority are not pathogenic o A few species can cause granulomas at the junction of squamous and glandular epithelium o Strongyloides can cause death if high parasite load ● Trichostrongyloid nematodes o Globocephaloides ▪ Occur in duodenum and feed on blood ▪ Can cause anemia o Hypodontus macropi ▪ Occur in cecum of wallabies and kangaroos ▪ Can cause intestinal bleeding and anemia o Paramcropostrongylus toraliformis ▪ Nodular lesions in the distal cecum of eastern gray kangaroos ● Fascioliasis due to fasciola hepatica o Liver flukes o Occurs in grazing marsupials o Usually well tolerated but can cause disease in smaller macropods

Answer 15

● **Toxoplasma gondii** o Reported in many marsupials and monotremes o Vertical transmission may occur or through oocyst ingestion via plants or soil contaminated with cat feces o T gondii bradyzoites are common in muscle of sheep in Australia; if raw meet is fed to small dasyurids they can develop neuro signs and die due to encephalitis o Significant cause of mortality in bandicoots, this species may be particularly susceptible o Signs are species dependent but can include neuro signs, resp signs, diarrhea o Tachyzoites are the most immunogenic life stage

Answer 16

**Fowler 10 Chapter 101 Macropod Progressive Periodontal Disease (Lumpy Jaw)** Abstract/Intro - Macropod progressive periodontal disease (MPPD, lumpy jaw) is a multifactorial progressive inflammatory and necrotizing polymicrobial disease associated with predominantly anaerobic opportunistic bacterial infection of the soft tissues and bony structures supporting the teeth, including gingivitis, periodontitis, and mandibular/maxillary osteomyelitis. - Specific bacteria, principally Fusobacterium necrophorum, have been proposed as etiological agents. - However, current evidence suggests MPPD is a more complex polymicrobial disease, and its epidemiology remains incompletely understood. - Disruption of normal molar progression is a predisposing factor - Dietary risk factors are poorly understood, but a an appropriate high-fiber diet that - reflects species-specific forage ecology is likely protective. - The prevalence of MPPD increases with age and is higher in animals that have previously had episodes of the disease. - Dental trauma, especially to the incisors, likely predisposes - Stressors that have been associated with MPPD include cold and wet weather, inadequate shelter, high stocking density, conspecific aggression, inappropriate contact with zoo visitors, confinement, vehicle noise, and moves between enclosures or institutions. MPDD in wild and captive populations - MPDD has been documented in the wild but prevalence is unknown - In the wild, drought conditions and high population density considered predisposing factors. - Prevalence in captivity is unknown, but MPPD is commonly cited as the most significant disease of captive macropods. Microbiology - Fusobacterium necrophorum (Fn) and bacteroides most commonly isolated - Fn–although frequently identified and its endotoxins very likely key drivers of disease, there is evidence that Fn is neither necessary nor sufficient to cause MPPD - A polymicrobial disease theory is supported, mostly comprised of anaerobes Pathogenesis and Epidemiology - Lesions are generally centered on periodontal tissues. - Gingivitis and periodontitis are commonly considered to the constitute early stages - Many cases progress to necrotizing osteomyelitis of the maxilla/mandible, with bony proliferation. - Necrotizing anaerobic infection can also spread to other organs - Some characteristics of molar progression in macropods, such as the persistence of “postfunctional” teeth beyond the period of direct occlusion, differ from other taxa - The premolar and rostral molars are the most common sites of disease, suggesting that post-functional teeth may be a risk factor. - Abrasive plant material has been proposed to be associated with gingival trauma and disease, but no definitive association has been found, and high fiber/more naturalistic diets are likely protective - Low fiber diet associated with plaque accumulation - Diet-induced gingival fragility could potentially make it more likely that rough plant material causes gingival trauma. - A range of stressors associated with MPPD (see abstract for list) - One study reported that odds of MPPD increased with the number of interzoo transfers - Macropods older than 10 years are at least seven times more likely to develop disease. - Fecal contamination of enclosures/environments is a proposed factor, Fn is a normal part of herbivore flora - One study–Fn isolate from a red kangaroo with MPPD was added to the feed of tammar wallabies for 8 months, and none of the wallabies developed MPPD Diagnosis, treatment, and prevention - Summarized in table below, but antibiotics alone not likely to be successful, need to remove affected teeth as well - Prevention is based on optimizing captive husbandry and identifying and addressing potential risk factors. - Several vaccines trialed unsuccessfully

Answer 17

JZWM 2022 53(2) 470-479 **HYPERLIPIDEMIA AND XANTHOMATOSIS IN YELLOW-FOOTED ROCK WALLABIES (PETROGALE XANTHOPUS) UNDER MANAGED CARE** Abstract Xanthomas are localized lipid deposits in organs with associated granulomatous inflammation. Xanthomatosis is a rare condition in both human and veterinary medicine and is often linked to inherited or acquired dyslipidemias. Three female yellow-footed rock wallabies (Petrogale xanthopus) at a single institution were diagnosed via biopsy with cutaneous xanthomas secondary to hypertriglyceridemia and hypercholesterolemia, and an additional two female yellow-footed rock wallabies were diagnosed with xanthomas at a second institution. All cases presented with cutaneous masses at the haired skin and paw pad junctions of the extremities, and/or mucocutaneous junctions of the face or urogenital tract. The clinically affected individuals were overconditioned or obese, had lipemic serum, and had elevations in blood cholesterol and triglyceride levels. When full lipid panels were performed, inverse high- and low-density lipoprotein fractions were observed. Six other individuals at the first institution had identical husbandry but were of more appropriate body condition, were normolipidemic, and had no xanthomas. One of the affected animals was also concurrently diagnosed with hepatic lipidosis via liver biopsy. Pedigree review and evaluation for underlying endocrine diseases such as hypothyroidism were performed. Because all affected animals were found to be related, a genetic predisposition is possible but requires further investigation. Consideration for the predisposition of some individuals for obesity, hyperlipidemia, and subsequent xanthoma formation should be factored in the husbandry and medical management of this species. Key Points - Yellow footed rock wallabies are an Australian marsupial of the family Macropodidae; inhabit cliff faces and rocky outcrops in S. Australia, New South Wales and Queensland - Lipemia - grossly visible plasma - hypertriglyceridemia - Lipoproteins: -- Chylomicrons - formed by enterocytes to endogenous dietary lipids -- VLDL -- LDL -- HDL - LDL and HDL mainly contain cholesterol - Xanthomas - lozalized lipid deposits in organs with associated granulomatous inflammation - Clinical presentation: -- Obesity -- Pink, raised dermal masses on paws, naris, muzzle, cloaca - Biochem findings -- Elevated GGT, Tbili, AST -- Lipemic serum -- hypertryglyceridemia, hypercholesterolemia (persistent) -- Inverse high density lipoprotein to low density lipoprotein ratio (persistent) - Pathology -- Cutaneous xanthomatosis, hepatic lipidosis, tracheal xanthoma in one case - Outcome -- One animal with due to self mutilation of ulcerated xanthoma mass -- One animal lost wt, cholesterol normalized, no xanthomas on necropsy 1 month later -- One animal had c/s and persistent lipemia and elevated TG, chol -- One animal had lost some wt -- All young adult females, obese, grossly lipemic serum, elevated TG and cholesterol, inverse ratio of HDL to LDL -- Affected wallabies had higher mean wt, chol, TG, LDL; and lower HDL -- 3/5 cases developed elevated liver enzymes, once case hepatic lipidosis via liver bx - Treatment - address the dyslipidemia -- 1 case had spontaneous resolution despite persistent hyperlipidemia Take home message - Hyperlipidemia and xanthomatosis in 5 yellow-footed rock wallabies; etiology undetermined - Lipid and thyroid panels routine in this species

Answer 18

**AN ENDOSCOPY-GUIDED TECHNIQUE FOR THE COLLECTION OF MICROBIOLOGY SAMPLES FROM THE TRACHEA OF COMMON WOMBATS (VOMBATUS URSINUS)**. Crosta L, Sawmy S, Schnitzer P. Journal of Zoo and Wildlife Medicine. 2023;53(4):882-886. Respiratory infections are common in young wombats and determining the causative agent is critical to establish an appropriate treatment. A group of 12 young, wild common wombats (Vombatus ursinus) ranging from 6 to 10 kg developed a range of respiratory signs after being in care following the severe bushfires in Australia in early 2020. The oral anatomy of wombats makes collection of tracheal samples difficult. An endoscopy-guided technique was established to collect microbiology samples aseptically from the anesthetized patients. A guarded, sterile swab was introduced in the mouth and inserted into the trachea of two wombats, visualizing the procedure with the endoscope. A similar technique is described for endotracheal intubation of small mammals. This approach allowed for a safe and aseptic sampling collection. A pure growth of Escherichia coli was cultured from the samples, and appropriate antibiotic treatment was established according to the antimicrobial sensitivity test. Background - Wombats and koalas order Diprotodontia -- 3 wombat species: common/bare-nosed, southern hairy-nosed, northern hairy-nosed - Wombats - grazers, only marsupials with a radicular hypsodont (elodont) dentition (open-rooted, continuously growing) - Seem to be predisposed to pneumonia, aspiration pneumonia common in young/debilitated hand-reared wombats -- Antibiotic dysbiosis limits which antibiotics can be safely used in this species Key Points - Instead of bronchoalveolar lavage or tracheal wash - used a side-by-side endoscopy technique to insert a guarded swab into the trachea for culture. -- Wombat in sternal recumbency, neck extended, head on folded towel, rigid 2.7 mm endoscope advanced to lift the soft palate then withdrawn to visualize glottis off to one side of the epiglottis -- Watched guarded sterile swab (equine gynecology swab) advanced into view then tip of swab was passed through glottis on inhalation -- Allowed for safe and aseptic sampling technique, similar technique to endoscope-guided intubation Conclusions - You can do a respiratory swab for culture using an endoscope-guided technique to place a guarded swab at the glottis and insert the sterile swab into the trachea.