CLINICAL ASSESSMENT AND INITIAL TREATMENT OF SICK AND INJURED BATS

Some injuries and illnesses of bats are overt and easily detected (e.g. flying-fox paralysis syndrome, barbed wire and netting injuries and direct trauma), while many are subtle and dependent on careful clinical examination and diagnostics (e.g.

2.1 Clinical history

History provides valuable information (e.g. found on the ground near a road, orphaned or hanging low in a tree not trying to escape). Clinical examination should com­mence with a distant examination in the carry cage or enclosure to observe demeanour, posture and obvious injuries or swellings. A normal bat should be hanging and able to voluntarily adjust the position of its feet and regrip (noting that in flying-foxes, gripping is passive whereas releasing the digits is an active voluntary movement). The eyes should be bright with clear corneas and the ears should be erect and constantly swivelling in response to sound. Wings should be wrapped around the body com­fortably, with the wingtips facing backward. There should be no obvious respiratory effort at rest.

2.2 Clinical examination

Every bat should be handled as if infected with ABLV, regardless of age or presentation. See WHA (2020) for more information on PPE for bat handlers. In order to perform a thorough physical examination, flying-foxes should always be handled by two rabies-vaccinated, expe­rienced handlers wearing appropriate PPE. This increases the ease of examination and safety of handlers and

Fig. 42.2. Flying-fox triage and assessment flow chart.

reduces stress on the flying-fox. A single handler is suffi­cient in the case of flying-fox pups or microbats. If an injury or illness is suspected that requires further exami­nation, the bat should be anaesthetised (see Chapter 9).

A thorough clinical examination should include, but not be limited to:

• Hydration assessment: indicated by the ease of movement of the skin over the sternum.

• Body condition assessment (Fig. 42.3)

• Examination of oral cavity: oral mucous membranes colour and refill time (Table 42.1), palate, trauma, tooth damage or wear

Fig. 42.3. Body condition scoring of Australian flying-foxes, based on palpated pectoral muscle mass.

Table 42.1. Clinical parameters for flying-foxes¹

¹ McMichael etal. 2016; Bartholomew etal. 1964; (T Bishop pers. comm.)

• Ocular examination: fluorescein stain. Exposure ulcers are common in flying-foxes as they dehydrate very easily (McMichael et al. 2016)

• Fur: evidence of depigmentation and poor fur quality due to malnutrition

• Wing and membrane examination: damage, bruising, contracture

• Palpation and manipulation of all long bones: frac­tures, dislocations, wings unable to be fully extended

• Abdominal palpation

• Radiographs: lateral and ventrodorsal

• Urine specific gravity (Table 42.1). Flying-foxes have minimal ability to concentrate urine

• PCV and total protein (Table 42.1)

• Blood glucose

Additional diagnostic tests may be warranted for particu­lar presentations.

2.3 Venipuncture

Venipuncture is described in Olsson and Woods (2008) and Appendix 2. Smith et al. (2010) describe a technique for collecting small quantities of blood from microbats. The bat is restrained between the thumb and palm, and the wing extended. The brachial or propatagial vein is punctured with a 25G needle and blood beading on the skin is collected in aliquots using a micropipette and ster­ile tip. Over 1000 Australian microbats from eight differ­ent species were bled using this technique, with an average collection volume of 4 μL per gram of body weight. Hae­matology and biochemistry reference ranges are included in Appendix I.

2.4 Stabilisation of the critical flying-fox

Flying-foxes that are sick or injured are frequently unable to fly and feed. At presentation they may be severely dehydrated and/or malnourished. Stabilisation of these patients is required before further diagnostic tests and treatment are undertaken.

2.4.1 Intravenous fluid administration in cases of moderate to severe dehydration

• Place cannula in saphenous (interfemoral) vein (see IV access below).

• Start on IV fluids +/- glucose.

• Cardiovascular system easily overwhelmed so keep fluid rates conservative (no greater than 4.5 mL/hr) and monitor closely.

• If dehydration or severe shock, use colloid 5 mL/kg, slowly (Mathews 2006).

• Wean off IV fluids slowly due to poor renal concen­trating ability (see Table 42.1 for normal urine specific gravity).

2.4.2 Subcutaneous or oral fluid administration in cases of mild dehydration

• If blood glucose is <3 mmol/L, give 10% BW SC fluids +/- glucose on the gingiva.

• No oral medication should be given until the flying­fox is well hydrated, very bright, alert and responsive, with normal ear movements and holding the head independently. Flying-foxes can aspirate very easily if they are weak and/or dehydrated.

• Transition to fruit juice and then high protein smoothies and fruit as tolerated once stabilised.

2.4.3 IV access

Flying-foxes tolerate IV cannulation and therapy very well. The key is using non-irritant tape on their sensitive membranes and taping in a way that does not compress the membranes around the leg and restrict blood flow,

Fig. 42.4. Cannulation of the uropatagial vein in a flying-fox. a) 22G cannula placed in uropatagial vein. Fixomull® tape over and under the membrane in natural position. b) Tape placed over the cannula with small gauze pad under the end of the cannula. Fixomull® tape placed over the top of the cannula and around the membrane without folding the membrane (causes swelling). c) U-shaped short extension set, primed and placed onto cannula and taped in place. Photos: Tania Bishop

which causes bruising and discomfort. Fixomull® (Essity, Victoria) is a good choice, as it has a good balance of adhesiveness and breathability. When placing a cannula, the vein can appear far more prominent than it is due to the thick muscular sheath surrounding the vein. There­fore, it is essential to hold the vein off and check for a flash of blood when giving an IV injection or before advancing the cannula for placement. See Fig. 42.4 for correct placement.

3.