DISEASES
A range of infectious and non-infectious diseases may affect dasyurids and numbats, some of which are covered in Holz (2008), Vitali and Monaghan (2008) and Ladds (2009). The discussion here presents new information or new diseases reported in dasyurid species since 2008.
Some diseases, including cutaneous mycobacteriosis, cardiac disease and ulcerative cloacitis, have been reported from multiple institutions. Tables 39.1 and 39.2 summarise selected infectious and non-infectious diseases recently reported in dasyurid species. The most significant disease of a dasyurid species is DFTD, which is covered in detail in Chapter 40.7.1 Infectious diseases
A range of infectious disease agents have been reported from dasyurids and numbats, but for some the clinical significance is yet to be determined. Mycobacterial infections have been reported in multiple species (Michael and Sangster 2010; Reppas et al. 2010; Kragic et al. 2015). These infections involve bacteria from the Mycobacterium avium-intracellulare complex or the rapidly growing Mycobacterium group and may arise in either immunocompromised or immunocompetent hosts. Disseminated skin infections (see Chapter 12) and pneumonia have been the most widely reported presentations (Michael and Sangster 2010; Reppas et al. 2010; Kragic et al. 2015).
7.1.1 Parasites
Internal and external parasites may cause clinical disease in free-ranging and dasyurids in managed care and may have a role in maintaining biodiversity of free-ranging populations by driving ecological and evolutionary adaptations. The tick species Ixodes holocyclus, I. fecialis and I. tasmani have been identified on northern quolls (D. hal- lucatus) from the Atherton Tablelands (Weaver 2014). Fleas and ticks from yellow-footed antechinus (Antechinus flavipes) were found to carry a novel Bartonella spp. and may be a vector for this organism (Kaewmongkol et al.
2011). Wait et al. (2017b) reviewed internal and external parasites reported in Tasmanian devils. Five parasites were found to be specific to Tasmanian devils (the nematode Woolleya sarcophili, the trematode Neodiplostomum sarcophili, the cestode Dasyurotaenia robusta and the sarcoptiforme mites Satanicoptes armatus and Diaboli- coptes sarcophilus) and are therefore at risk of extinction along with their host (Wait et al. 2017b). Seven parasite species were considered introduced, with Tasmanian devils being a naive host. Several parasites were recorded for the first time in Tasmanian devils, including oocysts of a trichurid nematode and Eimeria spp., as well as theTable 39.1. Selected infectious diseases of dasyurids.
| Condition/aetiology | Species | Clinical signs/pathology | Diagnosis | Comments |
| Dasyurid herpesvirus 1 and 21,2 | Agile antechinus (Antechinus agilis), yellow-footed antechinus (A. flavipes), Tasmanian devil (Sarcophilus harrisii) | Cytomegaly and intranuclear inclusions in prostate (antechinus), no clinical signs in Tasmanian devils | Histopathology | Associated with post-mating death in male antechinus |
| Leptospira spp.3 | Tasmanian devil | Single case of interstitial nephritis | Serology (microscopic agglutination test, microsphere immunoassay), PCR, histopathology | Widespread seroprevalence in wild populations to a range of serovars |
| Mycobacterium spp.4,5 | Tasmanian devil, spotted-tailed quoll (Dasyurus maculatus) | Cutaneous mycobacteriosis (primarily Mycobacterium fortuitum complex), pulmonary mycobacteriosis | Histopathology with acid-fast staining, culture, PCR | Prognosis guarded. Antibiotic therapy based on susceptibility testing. Single case of cutaneous mycobacteriosis successfully treated with doxycycline and moxifloxacin. Refer to Chapters 12 and 22 for more information |
| Pasteurellaecea bacteria6 | Tasmanian devil | Normal oral flora | Culture | May have relevance for bite injuries and zoonotic risk |
| Rickettsia tasmanensis7 | Tasmanian devil | Isolated from Ixodes spp. ticks removed from Tasmanian devils, clinical significance unknown | PCR | Genetically related to human spotted fever group rickettsia |
| Erysipelothrix rhusiopathiae8 | Numbat (Myrmecobius fasciatus) | Single case of mastitis in wild numbat | Histopathology, culture | |
| Salmonella meunchen9 | Numbat | None. Isolated on routine health assessment | Culture and serotyping | Zoonotic risk |
| Salmonella (various serotypes)10 | Tasmanian devil. Prevalence greater in wild devils compared to those in managed care. | None. Isolated on routine health assessment | Culture and serotyping | Zoonotic risk |
1Amery-Gale etal. 2014; 2Stalder 2013; 3Wynwood etal. 2016; 4Michael and Sangster 2010; 5Reppas etal. 2010; 6Brix etal. 2015; 7Steel 2010; 8Vaughan-Higgins etal. 2013; 9S Vitali pers. comm.; 10Michael etal. 2020
mite Neotrombicula novaehollandiae.
Molecular investigations into Cryptosporidium and Giardia parasites isolated from Tasmanian devils found novel genotypes, as well as a zoonotic strain of Giardia duodenalis (Wait et al. 2017a).Sarcoptiforme mites of the genera Uropsylla and Dasy- urochinus have been associated with a mange-like condition in free-ranging spotted-tailed quolls in northern NSW (Vilcins et al. 2008).
A novel species of Eimeria was identified in the prostatic tissue of a mature male yellow-footed antechinus (Amery-Gale et al. 2018). Necropsy examination of this individual also revealed concurrent infection with dasyurid gammaherpesvirus 1. The significance of the infection is unclear, but the location of infection suggests this parasite is transmitted sexually (Amery-Gale et al. 2018).
7.2 Non-infectious diseases
Dasyurids typically have a short life span, though age related changes have been reported in a range of species, in particular Tasmanian devils (Veterinary Specialist Advisory Group 2013). Conditions include degenerative joint disease, degenerative Ieucoencephalopathy and
Table 39.2. Non-infectious diseases and conditions of unknown aetiology (neoplasia is covered in Chapter 18)
| Condition | Species | Clinical signs | Diagnosis | Comments |
| Degenerative leucoencephalopathy and myelopathy1,2,3 | Tasmanian devil (Sarcophilus harrisii), northern quoll (Dasyurus hallucatus), eastern quoll (Dasyurus viverrinus) | Typically aged animals. Weakness and ataxia, loss of muscle mass. Particularly affects hindlimbs | Rule out other differential diagnoses. Lack of response to anti-inflammatories or analgesics | Prognosis guarded to poor. Monitor for progression. Consider euthanasia, particularly when animal welfare or risk of injury is of concern. Possible familial link |
| Cardiac disease (atrioventricular block, dilated cardiomyopathy)1,4,5 | Tasmanian devil | Aged animals. Weakness and lethargy, coughing, abdominal distension | ECG, thoracic radiographs, echocardiography | Prognosis guarded to poor. Has been successfully managed with implantation of pacemaker. Supportive therapy for congestive heart failure |
| Degenerative joint disease1 | Tasmanian devil | Aged animals. Lameness, stiff gait, weakness | Radiography | Prognosis guarded. Managed with analgesia/anti-inflammatory drugs and nutraceuticals. Monitor quality of life |
| Intervertebral disc disease1 | Tasmanian devil | Aged animals. Weakness and ataxia, particularly hindlimbs | Radiography including contrast studies, CT scan | Prognosis guarded. Managed with analgesia/anti-inflammatory drugs |
| Necrotising mastitis6 | Dibbler (Parantechinus apicalis) | Swelling and discolouration of mammary tissue. Typically during weaning/involution | History, examination | Prognosis guarded. Fatalities may occur secondary to septicaemia |
| Dermatitis6 | Dibbler | Single outbreak of pruritus, peri-orbital swelling and ventral erythema | Examination, skin scrapes | Treated with systemic and topical antibiotics |
| Nutritional secondary hyperparathyroidism7 | Tasmanian devil | Hindlimb weakness, lameness, pathological fractures | History (diet, handreared juveniles), radiographs | Prevent with appropriate diet including bone or calcium supplementation |
| Ulcerative cloacitis | Tasmanian devil | Localised vesicles and ulcers to cloacal mucosa | Examination, biopsy | Typically self-limiting |
1Veterinary Specialist Advisory Group 2013; 2Peck etal.
2019; 3Shopland etal. 2020; 4Campbell-Ward and Bryant 2016; 5Kragic etal. 2015; 6S Vitali pers. comm.; 7Muir and Doornbusch 2011myelopathy, atrioventricular block and neoplasia. Some of these conditions may present with similar clinical signs, including weakness, muscle wastage and ataxia, and may be difficult to differentiate on clinical signs alone. Continued degeneration or progression is likely and although some conditions can be managed with supportive therapy, regular review of quality of life should be implemented to ensure decisions to euthanase animals are made before welfare is compromised. Neoplasia other than DFTD is covered in Chapter 18.
Bradyarrhythmia, usually detected incidentally, due to atrioventricular block has been documented in aged Tasmanian devils. Electrocardiography (ECG) reveals bradycardia, often below 40 bpm, with lack of a QRS complex after multiple P-waves (Fig. 39.1). Left untreated, these cases may progress to develop congestive heart failure. Pathology can be variable but typically involves myocardial changes, including dilated cardiomyopathy (Plate 39.1), nodular valve disease and myocardial fibrosis, some of which can be diagnosed antemortem via echocardiography (Campbell-Ward and Bryant 2016). An aetiology for this condition has not been identified.
7.2.1. Toxicities
Important toxicities in dasyurids include bufotoxicosis, agricultural pesticides and vertebrate toxic agents such as sodium fluoroacetate (1080), para-aminopropriophenone (PAPP) and sodium cyanide. These are covered in
Fig. 39.1. Electrocardiogram tracings from (a) a healthy Tasmanian devil (Sarcophilus harrisii) and (b) a Tasmanian devil with 3rd-degree atrioventricular block. P-waves are identified with black arrows. Note the absence of QRS complex following most P-waves, together with intermittent abnormal ventricular contractions (black bar) in (b). Trace speed = 25 mm/s, height = 5 mm/mV.
Chapter 19. Renal papillary necrosis has been documented in eastern quolls receiving prolonged therapy with meloxicam (Shopland et al. 2020) and consideration should be given to dose rates, frequency and duration of therapy in this species, particularly if there is concurrent underlying renal disease or dehydration.
7.3 Diseases of uncertain aetiology
Ulcerative cloacitis has been observed in Tasmanian devils in managed care (L Vogelnest and T Portas pers. comm.). Clinical signs include vesiculation and ulceration of the cloacal epithelium (Plate 39.2), with histopathology showing loss of epithelium, variable inflammatory changes and in some cases eosinophilic intranuclear inclusion bodies. A herpesviruses was considered a potential aetiological agent on the basis of the intranuclear inclusions; however, virus isolation attempts were unsuccessful and herpesvirus DNA was not detected using panherpesvirus PCR in a subset of cases (J Devlin pers. comm.). The clinical significance of and the aetiological agent associated with this condition remain unknown.
ACKNOWLEDGEMENTS
I would like to acknowledge the assistance of Drs Larry Vogelnest, Simone Vitali, Michelle Campbell-Ward, Timothy Portas and Jo Devlin for providing material included in this chapter, and Kathy Starr for her patience.