DISEASES

A comprehensive review of the diseases of Australian bats is provided in Olsson and Woods (2008) and Ladds (2009). More recent literature is reviewed here.

3.1 Infectious diseases

3.1.1 Viral diseases

a.

Australian bat lyssavirus (ABLV) is covered in detail in Olsson and Woods (2008). An overview and update on current status are provided below.

Current status - ABLV is a rhabdovirus that is closely related to rabies virus. Australian flying-foxes and micro­bats are the natural reservoir hosts. The virus, first recog­nised in 1996, has been identified in all four mainland species of flying-fox (the grey-headed, black (P. alecto), little red (P. scapulatus) and spectacled flying-fox) and one species of insectivorous microbat, the yellow-bellied sheath-tailed bat (Saccolaimus flaviventris) (Field 2018). Serological evidence of ABLV exposure has additionally been found in a range of insectivorous bat species (Field 2018). All bats are considered susceptible to ABLV infec­tion. Two variants of ABLV have been identified: the pteropid and the yellow-bellied sheath-tailed bat variant (Gould et al. 2002).

ABLV can spill over from bats into other species. There have been three human cases of ABLV infection follow­ing a bite or scratch from a bat, most recently in 2013, and all have been fatal (Samaratunga et al. 1998; Hanna et al. 2000; Francis et al. 2014). In 2013 two horses sharing a paddock in Qld were found to be infected with the yellow- bellied sheath-tailed bat variant of ABLV. The horses showed pyrexia and progressive neurological signs (Shin- wari et al. 2014). This was the first detection of ABLV in a domestic animal. Natural ABLV infection has not been identified in dogs or cats. In 2013 a dog in NSW that had eaten a flying-fox was seropositive for ABLV, but there was no evidence of infection on postmortem testing (Wright 2013).

Clinical signs and pathology in bats - ABLV causes acute fatal neurological disease in bats, with death generally occurring within 10 d (Barrett 2004). Clinical signs are very variable and include paralysis, paresis, unusual vocalisation, tremors, seizures and changes in behaviour such as agitation and abnormal aggression. Infected bats may also present with apparent respiratory difficulties, sometimes as the only clinical sign (Barrett 2004). However, not all infected bats show clinical signs. Bats of any age may be infected, including juveniles (NSW DPI 2016). All bats should therefore be handled as if infected with ABLV, including neonates and juveniles being hand-reared.

Histological changes vary and are not always present. These include non-suppurative meningoencephalomyeli- tis and ganglioneuritis, sometimes with Negri bodies (intracytoplasmic inclusions) (Hooper et al. 1999; McColl et al. 2002).

Diagnosis - There is currently no reliable antemortem diagnostic test for ABLV. Serological tests, although useful for research purposes to assess past exposure to ABLV, have no diagnostic value. ABLV is diagnosed in bats by detection of the virus genome or antigen in tissue samples, with brain being the most important tissue for diagnosis (AHA 2021). Histopathology is not definitive, but can indicate a likely viral aetiology. Commonly used laboratory tests include fluorescent antibody test (FAT) and real-time PCR (qPCR), including specific assays for the pteropid and insectivorous variants of ABLV. Other tests include virus isolation and immunohistochemistry. The main method of virus characterisation is genome sequencing. Differential diagnoses for bats with neuro­logical signs include trauma (head and spinal injuries), bacterial meningitis, neural angiostrongyliasis, toxoplas­mosis and toxicities (e.g. lead poisoning and tick paraly­sis) (Barrett 2004; Sangster et al.

Surveillance - Studies indicate a prevalence of ABLV infection of <1% in wild bat populations (Field 2018). ABLV infection is more common in sick, injured and orphaned bats, especially those with neurological signs (Barrett 2004). A national dataset of bats tested for ABLV is collated by Wildlife Health Australia (WHA) and published regularly in ABLV Bat Stats (WHA Bat Health Focus Group n.d.). Bats are submitted for ABLV testing for a variety of reasons, including contact with a person or domestic animal, neurological signs including abnormal behaviour, and bats found dead or euthanased because of trauma.

Over 2000 bats were tested for ABLV from 2010 to 2016, of which 103 were infected. The proportion of bats testing positive each year ranged from 2.8% to 7.4% (Igle­sias et al. 2021; WHA Bat Health Focus Group n.d.). These figures are not representative of the wild bat population, as bats submitted for testing are more likely to be unwell, debilitated or displaying abnormal behaviour (Barrett 2004; McCall et al. 2005).

Management of human and animal exposure to ABLV - Anyone who handles bats must be trained in bat han­dling, have current rabies immunity (ATAGI 2017) and use appropriate PPE (e.g. WHA 2020; WHSQ 2016a; WHSQ 2016b).

ABLV is transmitted when the saliva of an infected animal is introduced via a bite or scratch, or by contamina­tion of mucous membranes or broken skin with saliva. In the event of such an exposure, even for apparently minor wounds or abrasions (Francis et al. 2014), medical attention should be urgently sought. Bite or scratch wounds should immediately be washed thoroughly with soap and copious water for at least 15 min and a virucidal antiseptic such as povidone-iodine or alcohol applied (CDNA 2022). Bat saliva in the eyes or mouth should be rinsed out immedi­ately and thoroughly with water. Contact with urine or faeces is not considered to pose a risk of infection with ABLV (CDNA 2022); however, as with any animal, thor­ough washing and rinsing with water is recommended.

For advice on management of domestic animals that have had contact with a bat, refer to your state/territory agriculture agency (e.g. QDAF 2016; NSW DPI 2019). If a bat is suspected to be infected with ABLV, the state/terri- tory agriculture agency must be contacted, as ABLV is a nationally notifiable disease in Australia. The AUSVET- PLAN disease strategy for lyssaviruses outlines the national policy for management of this disease (AHA 2021).

Management of ABLV risk in ex situ populations - Where bats are held in zoos or by wildlife carers, biosecu­rity practices are key to keeping them free of ABLV infection (e.g. enclosures that prevent contact with free- ranging bats and quarantine of bats entering the colony) (AHA 2021; QDAF 2017). Education, training, vaccination and PPE are all critical for the management of ABLV risk for staff and volunteers. Risk mitigation measures (e.g. physical barriers) will be needed where members of the public visit the site. If a person is bitten or scratched by a healthy bat from a managed colony, the outcome for the bat should be determined on a case-by-case basis. First aid should be implemented for the exposed person and medi­cal advice sought, as described above.

Any bat suspected with ABLV infection should be euthanased and tested and any in-contact bats isolated. If infection is confirmed, any bat that had been in direct contact and showing clinical signs should be euthanased.

In-contact bats without clinical signs may be managed through immediate release; isolation, monitoring and potential vaccination; or euthanasia. Vaccination of bats with a rabies vaccine has been used several times in Aus­tralia (with the necessary approvals) to manage situations such as this. Refer to the AUSVETPLAN disease strategy for lyssaviruses for further information (AHA 2021).

More information on ABLV is available from the fol­lowing documents and websites:

• Wildlife Health Australia. Fact Sheet: Australian Bat

Lyssavirus, www.wildlifehealthaustralia.com.au

• AUSVETPLAN Disease Strategy: Lyssaviruses, www.

• Communicable Diseases Network Australia (CDNA) Series of National Guidelines. Rabies Virus and Other Lyssavirus (Including Australian Bat Lyssavirus), www.health.gov.au

• Qld Department of Agriculture and Fisheries. Aus­tralian Bat Lyssavirus (including information for vet­erinarians), www.daf.qld.gov.au

• NSW Department of Primary Industries. Australian Bat Lyssavirus Guidelines for Veterinarians, www.dpi. nsw.gov.au

• Wildlife Health Australia Bat Health Focus Group.

ABLV Bat Stats, www.wildlifehealthaustralia.com.au

b. Hendra virus

Hendra virus is a paramyxovirus of the genus Henipavirus responsible for fatal infection in horses and humans in eastern Australia. Flying-foxes of the genus Pteropus have been identified as the reservoir host. A novel variant of Hendra virus, termed genotype 2 (HeV-g2), has been detected in flying-foxes and horses (Annand et al. 2021; Wang et al. 2021; Peel et al. 2022). Hendra virus is covered in detail in Chapter 43.

c. Other viruses

Novel coronaviruses have caused significant disease out­breaks in humans. Bats are natural hosts for a range of coronaviruses. Surveillance of bats in Australia for coro­naviruses (as reviewed in Peel et al. 2020) found betacoro­naviruses and alphacoronaviruses (Prada et al. 2019; Smith et al. 2016), but there have been no detections of severe acute respiratory syndrome coronaviruses (SARS- CoV-1, SARS-CoV-2) or Middle East respiratory syn­drome coronavirus (MERS-CoV) in Australian bats. Transmission of SARS-CoV-2 from humans to wildlife has occurred overseas (FAO 2024). Anyone interacting with mammalian wildlife, including bats, should take measures to prevent this occurring (WHA 2022).

Since the discovery of Hendra and Menangle viruses, several novel paramyxoviruses have been identified in flying-foxes in Australia, including Cedar virus, a heni- pavirus that appears to be non-pathogenic (Marsh et al. 2012; Barr et al. 2015; Vidgen et al. 2015).

Other novel viruses identified in flying-foxes include a poxvirus, herpesviruses and a retrovirus (O’Dea et al. 2016; McMichael et al. 2019; Sullivan et al. 2023).

2.4.4 Bacterial diseases

Bacterial pathogens of bats have received less attention than viruses, although they carry a high diversity of bac­terial species (Muhldorfer 2013). The zoonotic disease Q fever, caused by Coxiella burnetii, is traditionally asso­ciated with livestock; however, several Australian wildlife species are likely reservoirs. Coxiella burnetii was recently identified in flying-foxes in Qld, with 7 of 90 pooled urine samples testing positive (Tozer et al. 2014). Next-genera­tion sequencing was used to identify potential zoonotic pathogens in the faeces of grey-headed flying-foxes from urban colonies in Vic. Sequences associated with 34 potential pathogens were identified, including pathogenic Haemophilus and Salmonella species clusters (Henry et al. 2018). Leptospirosis in flying-foxes is covered in Olsson and Woods (2008). Antimicrobial-resistant Escherichia coli have been detected in grey-headed flying­foxes in rehabilitation and in the wild (McDougall et al. 2021; McDougall et al. 2022).

2.4.5 Fungal diseases

a. White-nose syndrome (exotic)

White-nose syndrome (WNS) is a fungal disease caused by Pseudogymnoascus destructans. It has caused significant declines in insectivorous bat populations in North Amer­ica, with mortality estimates over 6 million, regional extinctions, and risk of extinction of some species (Turner et al. 2011; Alves et al. 2014; Hoyt et al. 2016a). Since WNS was first recognised in New York State in 2006, it has spread steadily south and west through North America. P. destructans has also been found across Europe and in north-east China, but without the mass mortalities observed in North America (Puechmaille et al. 2011; Hoyt et al. 2016b). P. destructans has not been found in Australia (WHA 2019a).

WNS is a disease of hibernating bats. The fungus requires low temperatures to grow and can persist in the environment for long periods (Verant et al. 2012; Lorch et al. 2013). Fungal spores may be spread by humans on clothing, boots and equipment, representing a possible route of entry of the pathogen into Australia. Cave-dwell­ing insectivorous bats in colder southern areas are likely to be at risk if WNS were to enter Australia, in particular the critically endangered southern bent-winged bat (Miniopterus orianae bassanii) and the eastern bent­winged bat (M. orianae oceanensis) (Holz et al. 2019; Turbill and Welbergen 2020).

WNS exclusion testing should be considered in any microbat displaying any of the following clinical signs:

• presence of white or grey powdery fungus

• wing membrane damage (membrane thinning, depig­mented areas, flaky appearance, non-traumatic holes)

• aberrant behaviour (flying during the day, increased arousal/activity during a period of torpor)

• mass mortality.

National guidelines provide advice on collection and submission of samples for WNS exclusion testing and reporting of suspect cases (WHA 2023). Guidelines have been developed to assist response agencies in the event of an incursion of WNS into Australia (WHA 2017).

More information on WNS is available from the fol­lowing websites:

• Wildlife Health Australia, www.wildlifehealthaus- tralia.com.au

• Australian Government Department of Agriculture, Fisheries and Forestry, www.agriculture.gov.au

• USGS National Wildlife Health Center, www.nwhc. usgs.gov

• White-Nose Syndrome Response Team, www.whiten- osesyndrome.org

• US Fish & Wildlife Service national white-nose syndrome decontamination protocol, www.whiten- osesyndrome.org/topics/decontamination

2.4.6 Parasitic diseases

a. Angiostrongyliasis

Neural angiostrongyliasis in flying-foxes is covered in Chapter 24. Until recently, all reported cases in flying-foxes were due to Angiostrongylus cantonensis but A. mackerrasae has now been identified in a black flying­fox from Qld (Mackie et al. 2013). This is the first report of A. mackerrasae in an aberrant host and of a patent Angiostrongylus infection in an aberrant host. The impli­cations of this are unclear, as the pathogenicity of A. mackerrasae in humans is not well understood (Aghazadeh et al. 2015).

b. Toxoplasmosis

Toxoplasmosis occurs in a wide range of Australian mammals (see Chapter 21). Although it has been seen in bats overseas (e.g. Cabral et al. 2013; Dodd et al. 2014), clinical toxoplasmosis was reported for the first time in Australia in 2012 in two zoo-housed flying-foxes (Sang- ster et al. 2012). Details of these cases are provided in Chapter 21. There was no evidence of the route of expo­sure to T. gondii oocysts in these cases, but Sangster et al. (2012) suggest that it could have been through contami­nated food or the environment. The status of infection or disease in free-ranging bat populations is unknown, as immunosuppression and managed care conditions may have been contributing factors in these cases. Nonethe­less, toxoplasmosis should be considered as a differential diagnosis for neurological and systemic signs in flying­foxes (Sangster et al. 2012). Toxoplasmosis has also been diagnosed in a microbat (Vespadelus sp.) from Tas., in association with pneumonia (A Davis pers. comm.).

c. Haemoparasites

Flying-fox are known to carry haemosporidian parasites, in particular Hepatocystis spp. Two new species, Sprat- tiella alecto and Johnsprentia copemani, were described from black flying-foxes in Qld, based on morphological examination of historical samples from the 1970s (Landau et al. 2012a; Landau et al. 2012b). Although they may be an incidental finding in flying-foxes, haemosporidial schizonts were associated with granulomatous, eosino­philic pneumonia in a series of six little red flying-foxes from Qld (Gordon et al. 2015).

Overseas, bats are common hosts for trypanosomes. Austen et al. (2015) found Trypanosoma vegrandis in microbats and flying-foxes from WA. A novel species, T. teixeirae, was identified in a little red flying-fox from Qld. Unlike previous reports where infection was not associated with clinical disease, this flying-fox was mori­bund with anaemia and icterus (Barbosa et al. 2016; Mackie et al. 2017). See Chapter 26 for further discussion.

d. Cryptosporidiosis

Cryptosporidium was identified in faecal samples from urban-dwelling and managed flying-foxes in NSW and Qld, including four novel genotypes. C. hominis, which is generally specific to humans, was found in managed fly­ing-foxes and considered a zooanthroponotic transmis­sion. The pathogenicity of C. hominis in flying-foxes is unknown, but the finding demonstrates the potential for flying-foxes to play a role in this disease of public health significance (Schiller et al. 2016).

e. Nematodes

McLelland et al. (2013) describe an outbreak of skin dis­ease in the critically endangered southern bent-winged bat in SA caused by the nematode Riouxgolvania beve- ridgei. The parasite caused white skin nodules in a large proportion of the population, but did not appear to adversely affect the health of the bats.

2.5 Non-infectious diseases

2.5.1 Heat-related mortality events in flying-foxes

Heat stress from extreme temperatures has caused large-scale mortality events of flying-foxes and these events are likely to increase in frequency and severity with climate change. Between 1994 and 2007 more than 18 events were documented, with deaths of more than 30 000 bats (Welbergen et al. 2008). Individual mortal­ity events included over 3500 deaths in 9 colonies in NSW in 2002 (Welbergen et al. 2008), almost 5000 in Vic. in 2009 (van der Ree et al. 2009) and >45 500 deaths across 52 colonies in south-east Qld in 1 d in 2014 (Welbergen et. al. 2014). In 2019-20, eight heat events affecting 40 camps in south-eastern Australia caused the death of over 74 000 flying-foxes (Mo et al. 2022).

The black flying-fox appears to have a lower toler­ance to heat stress than other species, possibly because it has evolved in tropical areas where extremes of tem­perature are rare (Welbergen et al. 2008). As the range of this species expands southwards (Roberts et al. 2012), it will be exposed to heat events with increasing frequency. As a general rule, young flying-foxes and adult females are most frequently affected (Welbergen et al. 2008). Death from heat stress can occur when temperatures exceed 42°C, although the effect of other factors such as humidity is not well understood. Flying­foxes tend to display a sequence of thermoregulatory behaviour involving wing-fanning, shade-seeking and then panting and saliva-spreading (Welbergen et al. 2008).

The net impact of human intervention in heat stress events on the colony as a whole is not completely under­stood, and further research is needed to evaluate the impact and effectiveness of various response activities. A systematic review of heat stress interventions and treat­ment is provided in Mo and Roache (2020).

Intervention activities need to be carefully consid­ered in relation to camp structure and climatic condi­tions. Activities such as wholesale spraying of a colony with water may disturb the flying-foxes, which can cause them to take flight or move away from a cooler microhabitat (e.g. base of a tree), resulting in further heat stress. Increasing the humidity in a camp could potentially also reduce the ability of bats to cool them­selves (Mo and Roache 2020). Sprinkler systems are being used in some colonies. NSW DPIE (2017) and QLD DES (2023) recommend spraying highly distressed individuals by hand, providing that other bats are not disturbed. A second round of spraying is applied if the individual has not responded within 15 min. If still not responding the flying-fox may then be removed for treatment and rehabilitation. Flying-foxes should only be removed if immediate specialist veterinary attention is available, as these animals will be suffering from heat stroke with the potential for permament cell and organ damage.

To reduce the risk to people and protect the flying­foxes, only experienced people with current rabies immunity and wearing appropriate PPE (WHA 2020) should handle bats during a response to mass morbid­ity and mortality events from heat stress or other causes.

3.2.2. Other mass mortality events in flying-foxes

Since late 2020, unusual clusters of flaccid paralysis have been identified in flying-foxes in South East Queensland and North East NSW, particularly over the summer months (‘Flying-fox Paralysis Syndrome’). A broad range of testing did not identify a cause; however, a toxic or metabolic cause is considered most likely (Cox-Witton and Gordon 2021).

Mo et al. (2022) describe a series of significant flying­fox losses in eastern Australia in 2019-20 due to a pro­longed drought, which resulted in extreme heat events and the ‘Black Summer’ bushfires, followed by a period of heavy rainfall. These events resulted in substantial loss of foraging habitat, mortality of adults due to starvation and heat stress, and pup mortalities due to maternal abandon­ment or separation.

Juveniles presenting in these types of events may be born prematurely, underweight to emaciated, dehy­drated, hypothermic and hypoglycaemic. Many present with aspiration pneumonia due to reduced swallowing reflex from weakness and hypoglycaemia. Treatment includes gradual warming of no greater than 1°C per minute, SC fluids and glucose on gums. The presence of aspiration pneumonia should be assessed by radiogra­phy, as flying-foxes with pneumonia often only display dyspnoea at a very advanced stage. Many pups require a gradual return to feeding, with SC fluid supplementa­tion to avoid malabsorption and potential aspiration until a normal feeding regime can be achieved. Oral sup­plementation should be avoided until euthermia has been achieved, and fluid and glucose deficits have been corrected via SC or IV routes. A feed with an oral rehy­dration product can be trialled once aspiration has been ruled out or treatment initiated, the pup is bright with a good swallow reflex, and hydration and hypoglycaemia have been corrected. If this is tolerated well, the pup can go to a rehabilitator on a refeeding regime, with twice weekly rechecks for growth and development assessments.

3.2.3 Trauma

Flying-foxes are increasingly found in urban areas, result­ing in trauma from entanglement in fruit tree netting and barbed wire, dog and cat attacks, electrocution, gunshots and motor vehicle collisions (Fig. 42.5) (Tidemann and Nelson 2011; Scheelings and Frith 2015). As well as the effect on individual bats, these events often result in con­tact with humans, with the associated risk of transmis­sion of ABLV (see section 3.1.1a).

Netting and barbed wire entanglements can be pre­vented through wildlife-safe practices (e.g. using appro­priate material and mesh size for fruit tree netting, keeping nets taut and replacing the top strand of barbed wire fences with plain wire). Several organisations pro­vide advice on wildlife-friendly netting and fencing (QG 2017; Wildlife Friendly Fencing Project 2018).

Injury management

Olsson and Woods (2008) describe the management of injuries and surgical treatment. Management of wounds and injuries in bats can be challenging. The fine struc­tures (skin membranes and bones) in the wings and per­sistent licking and chewing of wounds and dressings by the patient inhibit healing. New adhesive and colloidal hydroactive dressings are useful, promoting wound heal­ing, particularly where bone is exposed. The extent of patagial or wing membrane damage may not be initially apparent following an injury or electrocution, making assessment of prognosis challenging. It may take up to 1 wk for the extent of the injury to become apparent after subsequent ‘die back’ of the membrane (Fig. 42.5a).

Injuries to the thumb (digit 1) are common in flying­foxes and often require amputation. The thumb is impor­tant for flight, manipulating food, fighting and for hanging when defecating and urinating. Therefore, loss of both thumbs may be considered an indication for eutha­nasia (Olsson and Woods 2008). For flying-foxes with one remaining thumb, the following criteria may be used to determine suitability for release (S Frith pers. comm.):

• well-healed skin over the stump with no evidence of abrasion from normal activity in a pre-release aviary

• normal ability and speed in vertical climbing of a tree trunk and manoeuvring around branches

• ability to invert (hang) to urinate and defaecate

• ability to carry an infant and hang (difficult to assess in females without an infant).

Older bats may find it more difficult to adapt to thumb loss. When amputating a thumb it is preferable to keep as much of the stump as possible. Wound healing over digits can be poor and hampered by licking. Flight may be impaired if there is significant loss of patagium associated with the loss of the digit (Olsson and Woods 2008). Loss of digits 2-4 of the pes has a better prognosis for release than the loss of digits 1 and 5, as these allow for more natural span and weight bearing of the pes (S Frith pers. comm.).

A small study in black flying-foxes in Townsville, Qld, found that loss of teeth did not affect body condition (Luly et al. 2015), possibly because their diet is based pre­dominantly on floral food sources rather than hard fruit. The authors suggest that although further work is neces­sary, the findings may apply to other flying-fox species and regions where blossom is the main food source.

Careful consideration must be given to individual animal welfare, human safety and population biology when assessing orphaned, injured or sick bats before and during treatment and rehabilitation (see Chapter 4).

Fig. 42.5. Damage caused by (a) electrocution and (b) barbed wire entanglement. Photos: Tolga Bat Hospital

3.2.3 Toxicities

a. Tick paralysis

The spectacled flying-fox, a threatened species with a limited range in north Qld, is affected seasonally by the paralysis tick (Ixodes holocyclus), resulting in significant mortality. Details of this disease were described by Olsson and Woods 2008. Buettner et al. (2013) analysed tick paralysis cases from Tolga Bat Hospital, Qld. The number of affected bats per year ranged from 165 to 720, but extrapolation for missing data suggests numbers may be as high as 1580. Mortality rates of up to 102.5/10 000 bats were calculated. The epidemiology of this disease is not well understood and it is not clear why it occurs regularly on the Atherton Tablelands, but not in the coastal colonies of this species. Hypotheses include an association with the presence of the low- growing invasive wild tobacco bush (Solanum mauri- tianum) (Buettner et al. 2013), or lack of development of adaptive immunity in this species.

b. Pesticides and other contaminants

Pesticides and other contaminants may contribute to the decline of bat populations (Olsson and Woods 2008; see Chapter 19). Bats may be exposed to toxic chemicals directly or via food sources such as insect prey. Bayat et al. (2014) review the effect of organic pollutants on bats.

Diphacinone, a first-generation anticoagulant rodenti­cide, caused the poisoning of over 115 lesser short-tailed bats (Mystacina tuberculata) in NZ in 2009 (Dennis and Gartrell 2015). The route of ingestion was unknown, but direct consumption of toxic bait or secondary poisoning through insect consumption was possible. Affected bats showed bruising and haemorrhage, and diphacinone was detected in liver samples. Of seven bats admitted to a vet­erinary hospital, only three pups responded to treatment with vitamin K. Although this species does not occur in Australia, the authors suggest that microbats may have higher sensitivity to diphacinone than other mammals.

3.2.4 Deformities

The congenital defects of spectacled flying-fox neonates reported by Olsson and Woods (2008), including cleft palate and orthopaedic abnormalities, continue to occur and a cause has not been determined (McMichael et al. 2023).

A progressive wing deformity of hand-reared flying­foxes has been reported, particularly in spectacled fly­ing-foxes (J Mclean and T Bishop pers. comm.). It has been called ‘forward-facing wings’ or ‘bent-wing’ because the forearm becomes curved, such that the tip of the wing is at the front of the body rather than flexed over the elbow. It appears that the forearm and digits grow more rapidly than normal, causing bowing and dislocation of the phalangeal joints. It can be unilateral or bilateral (Fig. 42.6) and usually becomes apparent from around 10 wk of age. Although nutritional or

Fig. 42.6. Spectacled flying-foxes (Pteropus conspicillatus) with (a) bilateral and (b) unilateral (right) wing deformity. Photos: Tolga Bat Hospital

environmental factors (e.g. UV light) have been sug­gested, the cause is unknown.

There is another form of forward facing wings seen in all pteropid species, where the digits naturally start to fold forward rather than the normal backward position (T Bishop pers. comm.). This is most commonly seen in 8-10 wk old flying-fox pups that have been involved in a starvation event. It is usually bilateral but can be unilat­eral. No overgrowth of the bones are involved. The joints uniformly appear swollen and therefore more mobile. If diagnosed before the first growth spurt at around 12 wk, the condition is easily reversible through manual correc­tion whenever seen in the incorrect position, and the aid of meloxicam and pentosan in some cases. After this age the condition becomes permanent and the pup will not be able to fly.

Acknowledgements

We would like to thank Jenny Mclean for contributing the Husbandry section of this chapter and Sarah Frith, Justin Welbergen, John Bingham, Terry Reardon, Andrea Reiss, Anita Gordon, Alison Peel, Lee McMichael, Andrew Davis, Annabelle Olsson, Gabrielle Tobias, Stephanie Shaw, Andrew Hill, Tiggy Grillo and Rupert Woods for unpublished observations, text review and guidance.