Chapter Nine

PUBLIC HEALTH CONCERNS
The common misconception that bats are asymptomatic carriers of rabies persists, even within the veterinary profession. This misconception typically results in veterinary practitioners refusing to assist wildlife rehabilitators in treating bats. It is true that rabies is an extremely serious disease, but it is rarely encountered. Less than one half of 1 percent of bats contract the virus (Tuttle, 1988).

House bats, and most other bats in the United States, do not experience outbreaks of rabies; instead, only an occasional animal becomes infected (Constantine, quoted in Tuttle, 1988). By practicing appropriate handling techniques and maintaining high quarantine standards, there is no reason why veterinarians cannot safely treat bats and other rabies-susceptible mammals. The following are bat-related health problems of public concern:

Rabies
Rabies and rabies-related viruses are in the genus Lyssavirus, family Rhabdoviridae. Although viruses within this family have been isolated from vertebrates, invertebrates and plants, only those from mammals are pathogenic to humans. Several known mammalian lyssaviral categories, hosts, and relevant diagnostic and prophylactic problems were summarized by Constantine (1993).

The virus typically enters the body via the bite of an infected animal. Other modes of infection occur rarely; for example, via ingestion of infected food (Bell and Moore, 1971), inhalation of virus-saturated air (Constantine, 1967), or through contact with mucous membranes, open wounds or abrasions (Constantine, 1988). It is essential therefore, that veterinarians who are performing surgery or necropsies, wear gloves to prevent exposure to potentially infected tissues or fluids.

Behaviorally normal bats may incubate rabies for a year or more before clinical signs manifest. Moore and Raymond (1970) reported an incubation period in the big brown bat (Eptesicus fuscus) of 209 days after capture, and it died 4 days after the disease was clinically apparent. The virus, however, is not transmitted via a bite until it is present in the saliva. Constantine (1988) reported that rabies virus is often present in the host's saliva for one to several days before the appearance of clinical symptoms. Baer and Bales (1967) reported that a bat had the virus in its saliva 12 days before clinical signs became apparent. Because the incubation period for rabies in bats can be long, appropriate quarantine procedures should be practiced for a duration of at least 6 months.

In bats, the symptoms of rabies may be characterized by several or all of the following: anorexia, dehydration, restlessness, disorientation, sensitivity to light, sound and touch, and paralysis (especially of the muscles of the throat and hind limbs). I have observed rabies infection in one red bat (Lasiurus borealis) and 6 big brown bats (Eptesicus fuscus). Dehydration and paralysis were observed in the red bat and one big brown bat. The other big brown bats exhibited dehydration as well as hypersensitivity to touch, whereby they furiously chewed at the cloth in which they were being handled. Appetite loss reported in the literature actually may be caused by dehydration. All of the rabid bats in my care also exhibited anorexia, but after rehydration with lactated Ringer's solution, ate well until approximately the last 24 hours of life.

Rabies protection with pre-exposure immunization is essential for all handlers of animals in the orders Chiroptera and Carnivora. Constantine (1993) reported that a minimum antibody titer of 1:5 was sufficient for protection against rabies, but because it is thought that the current rabies vaccines may be less effective against bat rabies, a higher titer may be preferable; how much higher was not suggested. It must be cautioned, however, that the work of Fekadu et al. (1988) and Schneider et al. (1986) demonstrated that protection against infection may be partial, or not at all, with the use of current vaccines and globulins against some lyssaviruses.

For more detailed information on rabies and rabies-related viruses, the reader should consult Constantine (1988, 1993), Baer (1991), and Brass (1994).

Infection occurs by inhaling the fungal spores. The severity of the disease is determined by the number of the spores inhaled. In severe cases, symptoms may mimic tuberculosis, but many infections are asymptomatic. Normally, symptoms approximate a slight chest cold.

To prevent histoplasmosis, avoid stirring up and breathing dust where bird or bat droppings have accumulated. When in an environment where such dust becomes or will become airborne, use a properly fitting mask capable of filtering particles as small as 2. It is also advisable to wet guano deposits to minimize airborne dust particles.

Diagnosis is by histoplasmin skin testing. However, false positives may result if the infected person has been exposed to other mycotic agents. A more reliable diagnosis is by isolation of the fungus in sputum, blood, urine, or pulmonary lesions.

Constantine (1988) reported that severe cases of human histoplasmosis were treated with amphotericin B, but surgery is often indicated.

ANIMAL HYGIENE

Quarantine
All incoming wild bats should be isolated from other animals. If they are to remain in captivity, the quarantine period should be at least 6 months. During this time, conduct a thorough physical examination, paying particular attention to the likelihood of dehydration. Chemical erradication of ectoparasites is not necessary. If enclosures are cleaned daily, the parasites eventually disappear (also see Parasites below, discussed under MEDICAL PROBLEMS).

Enclosure Maintenance
To control pathogens, clean cages daily. Change the substrate and remove uneaten food and drinking water. To prevent the spread of infectious diseases or parasites, avoid transferring cage contents from one cage to another, and clean cages, glassware, and instruments of sick animals last. Cages should always be cleaned and disinfected following the illnes or death of a bat, and before new animals are placed in them. Keep extra clean cages be available to hold animals during scheduled cage cleaning.

Cleaning and Disinfecting
One of the most effective and inexpensive disinfectants is household bleach. Bleach, however, is difficult to rinse away and, if not diluted properly, can cause eye and skin irritation. A 1% solution of household bleach is sufficient to help reduce unpleasant odors from accumulated urine. Many animal facilities use pressurized steam for cleaning cages. When practical, scalding hot water is also effective for this purpose. Small cages then may be dried under natural sunlight for two or three days.

MEDICAL PROBLEMS

Dehydration
Virtually all sick, injured or orphaned bats become dehydrated. Mortalities may be reduced substantially by rehydrating bats immediately, and before further treatment, with lactated Ringer's solution, subcutaneously, one to three times a day (see TABLE 13 for dosages). A bat will rehydrate within one to three days depending on its medical problem. It will usually accept food after the second or third injection of lactated Ringer's solution, and food must be offered by hand to insure it receives adequate nutrition. A dehydrated bat probably has not fed voluntarily because it produces little or no saliva, making it difficult for the animal to swallow.

Diarrhea
Diarrhea in captive bats is usually associated with diet and/or stress. Dietary causes include the feeding of spoiled food, especially when feeding nectarivorous and sanguivorous bats, or "bat glop" as a substitute for insects. Other dietary causes of diarrhea include over-feeding or over-supplementing the diet with multivitamins. Causes of stress-induced diarrhea include shipping, change in caging, over-handling, incompatible cage mates, a noisy environment and, depending on the species, exposure to inappropriate lighting and/or prolonged exposure to humidities below 30% and above 80%. Viruses, bacteria and endoparasites can also cause diarrhea in bats.

Injuries
Among wild bats, most injuries include broken bones and/or tears in wing membranes, primarily from cat attacks. Simple fractures and minor wing tears usually heal within a month with little or no medical assistance. Wallach and Boever (1983) reported using disposable syringe barrels to fashion splints. They also warned against using products containing procaine. Because the webbing of bats' wings is highly vascularized, too much procaine is absored, with the consequence of severe depression.

Lollar (1994) gave detailed instructions on gluing wing fractures, but failed to explain how to maintain blood flow across the fracture-line through the glue. She also did not report the number of successful treatments achieved.

It is virtually impossible to repair compound fractures in small bats, much less to expect the animal to regain normal flight. The most sophisticated attempts have been made using intramedullary pins fashioned from appropriately sized hypodermic needles or stainless steel wires. The following case is typical of such surgical attempts: a little brown bat (Myotis lucifugus) was presented at a veterinary clinic with a 2-week-old compound fracture of the left wing, just below the elbow. An intramedullary pin was fashioned from a 20-gauge hypodermic needle. The surgical site was bandaged for approximately 6 weeks with biweekly changes. Each change of bandages required general anesthesia. The fracture failed to heal, but surgery  

was repeated successfully. Since the surgery, however, the bat's wing membrane sloughed away (FIG. 88), he chewed off his dessicated fourth and fifth fingers, and is unable to extend or flex his second and third fingers. Additionally, the bat broke off his left thumb as it protruded from the bandages, and for unknown reasons also lost the claw on his right thumb. Although the bat is permanently handicapped, he is otherwise healthy and being used in educational programs.

Figure 88.  Little brown bat (Myotis lucifugus) with healed wing injury (photo courtesy of Patrick Matheny, Moose, WY).

French (1994) gave an account of red bats (Lasiurus borealis) dying of infection if injured wings were not surgically amputated. Unfortunately, she failed to report on the survival rates and durations of bats which underwent surgical amputations. Nevertheless, amputation is indicated in cases of life-threatening infection. It must be emphasized that red bats are highly susceptible to infection and septicemia. These animals have extremely delicate tissues, and they can be fatally injured if they are not housed in a cage with soft sides and a sheepskin substrate.

Because of the many surgical failures routinely reported to me, I previously advocated euthanasia for most bats presented with compound fractures. Recently, however, I received a confiscated big brown bat that has changed my thinking in favor of allowing most compound fractures to heal without surgical intervention. FIGURE 89 depicts the animal's condition upon delivery. Except for routine wound cleaning, the bat received no veterinary care. On arrival at my facility, the bat was placed in a hard-sided cage (FIG. 26, Chapter 5) typically used for housing crevice-dwelling bats. To prevent skin 

abrasions, sheepskin was placed on the cage floor. The bat's humerus shattered approximately 1 month after she was received; nevertheless, she quickly learned to maneuver by stabilizing her left side with her shoulder, and she is now being used in educational programs.

Figure 89.  Big brown bat (Eptesicus fuscus) with healed wing injury.

The decision to perform surgery, or to allow natural healing of compound bone fractures must be weighed against several factors such as the species of bat, condition and age of the wound, and the amount of additional stress one is willing to place on an injured animal.

Parasites
Bats worldwide support microbes and parasites similar to those found in other mammals. In captivity, mites are the most troublesome to control when strict quarantine is not observed. Of particular interest is the fact that bat parasites usually disappear after several weeks when caging and bedding are cleaned daily. When chemical erradication is required, however, the treatment of choice is insecticidal no-pest strip (dichlorvous vapor). Avoid the use of other products; Constantine (1986b) warns that bats are highly susceptible to the adverse effects of chlorinated hydrocarbons such as DDT (dichlorodiphenyl trichloroethane), which is still available in many countries, Chlordane, Lindane, Toxaphene, Strobane, Endrin, Heptachlor (epoxide), Methoxychlor, Aldrine and Dieldrin.

Individuals who rehabilitate bats in their homes should isolate these animals from household pets, as bats may become infested with their pets' ectoparasites. On several occasions, I have heard that bats had to be treated for mange, ear mites and fleas acquired from pets. Treatment for bats in these situations is the same as it is for other mammals, but dosages must be reduced considerably.

The treatment of choice for coccidiosis in bats is the same as it is for other mammals. Trimethoprim/sulfamethoxazole suspension (under many trade names) has proven successful at a dosage of 15 mg/kg of body weight (concentration of 40 mg of trimethoprim and 200 mg of sulfamethoxazole per 5 cc) twice daily for 8 to 10 days. For example, to treat bats weighing approximately 20 g, mix 2 drops (0.10 cc) of suspension in 0.4 cc of tap or distilled water. Administer 0.25 cc of the solution in the morning and again in the evening. I have also used fenbendazole (Panacur®) in the treatment of intestinal nematodes at a dosage of 50 mg/kg of body weight once daily for 3 days. Repeat in 3 weeks if necessary.

Also, bat workers who are eager to provide a natural diet for frugivorous bats may accidentally include poisonous plants in their salads. For a listing of edible flowers and plants, see TABLE 14.

The major cause of poisoning in insectivorous species is from ingesting pesticides sprayed in the environment. Typical symptoms of poisoning include a hunched back, drawn-up legs, excessive salivation, rapid respiration, increased, irregular or slow respiration, tremors, incoordination, hindquarter weakness and/or stiffness, and lethargy.

When poisoning is suspected, administer supportive therapy. Treatments include activated charcoal, calcium gluconate, atropine sulfate, diuretics and fluids. Follow dosages directed on package labelling; fluid dosages are presented in TABLE 13. Controlling central nervous system stimulation with diazepam or barbiturates may be indicated.

Of particular interest is the potential for poisoning insectivorous bats by feeding mealworms (Tenebrio molitor). Ladisch et al. (1967) reported on the occurrence of quinones in grain, flour, and fungus beetles in the family Tenebrionidae. Flour exposed to quinone vapors binds 350 ppm of it within 1 hour. Although further studies are necessary, it can be theorized that quinone secretions from mealworm beetles can contaminate the food-bedding in which larvae grow. The contaminated Tenebrio larvae are then fed to captive bats, with possible toxic effects. For example, larvae purchased from a dealer may contain toxic levels of quinones. Assuming this is true, it is not known how long the larvae remain toxic after being placed in fresh medium. One such incident occurred in a captive big brown bat (Eptesicus fuscus). The principal diet of the bat was fortified mealworms that had been maintained in fresh medium for two weeks prior to feeding them to the bat. Depigmentation of the the bat's membranes (FIG. 90) was noticed first, and the problem worsened with time. The bat also exhibited dry, flaky skin, hair loss (FIG. 91), dehydration, loss of appetite and cessation of self-grooming. Three months later, the bat was presented for necropsy. Unfortunately, all tissues were autolyzed. The only diagnostic lesion was hemorrhagic lungs. Bacteriology produced beta hemolytic Streptococcus in lung tissues, and the spleen contained Bacillus sp., Escherichia coli (non-hemolytic), Proteus sp., as well as beta hemolytic Streptococcus. Chemical analysis of the viscera was positive for hydroquinone at an estimated concentration of 10-20 ppm.

Figure 90.  Big brown bat (E. fuscus) showing clinical symptoms of hydroquinone poisoning.  Arrows point to depigmented areas of the skin (photo courtesy of Lynn Sage, Museum of Discovery and Science, Ft. Lauderdale, FL).

Until further information becomes available, do not allow mealworms to metamorphose. This is easily achieved by maintaining them in the refrigerator. With no beetles to secrete quinones in the food-bedding (also referred to as medium), larval contamination to bats can be minimized. Furthermore, maintain newly purchased mealworms in fresh medium, as described in Chapter 14, page, for a minimum of 2 weeks before feeding them to bats. For additional information on caring for mealworm larvae, refer to Chapter 14, MAINTENANCE OF INSECT COLONIES.

Bats may become seriously ill after ingesting mealworms which have ingested styrofoam. When bats are held in styrofoam coolers, all container contents must be removed daily to search for and eliminate any mealworms that may have adhered to bedding.

Petroleum Contamination
Whitman (no date) reported the use of Whisk® Adhesive Remover Pads to remove a common vampire bat (Desmodus rotundus) from a mouse glueboard trap. To prevent the bat from resticking to the glueboard during the removal process, flour was dusted on it. The bat was then rinsed, presumably in water (author failed to say), to rid the fur of the adhesive remover. The bat was warmed with a heat lamp and fluids were administered subcutaneously. It may take several applications, over an equal number of days, to eliminate all of the product.

Lollar (1994) described using dishwashing detergent to remove No Roost® from Mexican free-tailed bats. As with the technique described above, it may take several applications and rinses to remove the adhevsive.

Roofing tar and oil may be removed with WD-40® (Lollar, 1994). WD-40®, however, is extremely toxic, so every effort must be made to wash it off a bat's fur, presumably with soap and water (author failed to say).

Hair Loss
Unnatural hair loss can be caused by dietary deficiencies, disease, or poisoning (FIG. 91). Loss of hair, however, occurs naturally in bats during their spring molt. Female bats maintained in a captive breeding colony may lose hair behind their heads when males cling to this area while copulating with them.

Figure 91.  Arrows point to hair loss across neck region of a big brown bat (E. fuscus) from hydroquinone poisoning (photo courtesy of Lynn Sage, Museum of Discovery and Science, Ft. Lauderdale, FL).

PHYSICAL EXAMINATION
Racey (1987) suggested examining bats only while they are torpid, as bats at active temperatures may become agitated, and suffer further injuries. If necessary, refrigerate a bat (heterothermic species only) for approximately 30 minutes before examination. Quickly check for broken or dislocated bones, open wounds, torn or pierced membranes, and symptoms of respiratory disorders. If a bat appears uninjured, assess its ability to hang and to fly. Be aware that dehydration (see discussion above) and starvation usually render a bat too weak to fly. One other cause preventing a bat from taking flight in captivity is space. Some bats (e.g., those with narrow wingspans) require a large area in which to become airborne.

CLINIC ENVIRONMENT
All bats, especially heterothermic species (discussed in Chapter 1), must be maintained at ambient temperatures of 80-85 F (27-29 C) when anesthesia is being administered, or when treating them with antibiotics or other drugs. Regardless of the species, if a sick bat does not respond to treatment with lactated Ringer's solution within 24 to 72 hours, begin administering the appropriate medication(s) while continuing hydration.

Sick or injured bats, weighing 4 g to approximately 100 g, can be placed temporarily in appropriately sized styrofoam containers that measure approximately 24 in. (61 cm) wide X 16 in. (41 cm) deep X 16 in. (41 cm) high). Lollar (1994) suggested the use of a similar-sized Rubbermaid® plastic tub. In either case, cut a relatively large opening in the top of the container and tape a piece of metal screen (FIG. 92a) over the opening on the OUTSIDE of the container. Be sure to use tape that will not lift up (e.g., strapping tape). Place a lamp over the container with a 25 W red-colored bulb. If the animal is a red bat, be sure to line the interior with drapery (FIG. 92b), using Velcro®. Bats weighing over 100 g can be placed in appropriately sized plastic pet carriers with mesh-lined top and sides (FIG. 18, Chapter 4). Depending on the medical situation, warmth can be provided with either a carefully monitored heating pad or with a 250 W lamp with a red-colored bulb. Never place heating pads on the cage bottom. Bats generally seek out the highest point in a cage, and forcing them to the bottom for warmth may be stressful. Also, heating pads on cage bottoms cause a bat to lie horizontally, rather than in the normal upside down position which, over an extended period of time, may result in swollen joints.

Figure 92.  Styrofoam coolers can be modified to house temporarily sick and injured bats weighing up to approximately 100 g.  A 25W lamp, with a RED bulb, is sufficient to maintain temperatures at 80-85 F (approximately 27-29 C).  A) cooler exterior showing modification of top and placement of lamp (use metal screening);  B) modification necessary for red bats (also include a branch or attach mesh to the cooler top);  C) cooler interior showing "furniture" for crevice-dwelling species (illustration from Barnard, 1992;  photo courtesy of Gregory C. Greer, Marietta, GA).

Provide food and water ad libitum. To prevent a bat from becoming wet, be sure the water is placed as far away from the perch as possible. Add 0.3% by volume vitamin B complex either to the lactated Ringer's solution for injections, or to the sick bat's drinking water.


FLUID ADMINISTRATION
FIGURE 93a illustrates the proper injection site for small bats. When injecting bats, they should be restrained in a soft cloth with the injection site exposed (FIG. 93b). It may be necessary to wear gloves when handling vampire bats and large species of fruit bats, although many workers wear gloves with all species. For fluid dosages, see TABLE 13. Evans (no date) recommends 0.05 cc/g/day of fluid. This dosage is also the maximum comfortable stomach capacity of most mammals.

Figure 93.  A)  injection site for small bats (photo courtesy of Lee Gilman, Charlotte, NC);  B) proper procedure for injecting small bats (photo courtesy of Gregory C. Greer, Marietta, GA).

ANTIBIOTICS
Most care givers are quick to use systemic antibiotics when faced with an injured bat. Helliwell (in litt.) reminds us that dosages and toxicity of antibiotics to bats are unknown, so antibiotics are not recommended for routine treatment; rather, only in cases of severe illness, and then preferably after culture and sensitivity tests. The following antibiotics have been used in bats (dosages have been derived empirically): Helliwell (in litt.) reported that ampicillin daily was successful when used either orally or injected subcutaneously, at 10 mg/Kg. Helliwell also reported that lincomycin, given orally, was successful at a dosage of 0.5 ml/Kg, twice daily. I have had success with Bactrim™ (see Parasites above for dosage), and Baytril®. Baytril® injectable solution (2.27% concentration) at a dosage of 2.5 mg/Kg may be diluted as follows: mix 0.04 ml Baytril® with 0.96 ml sterile dilutent. Deliver 0.10 ml/10g body weight, twice daily, for 8-10 days. The first two treatments should be delivered subcutaneously and the balance orally. For oral doses, mix the diluted Baytril® with an equal part of sweet nectar such as banana or guava.

ANESTHESIA
The literature contains several methods for anesthetizing various bat species (Beck, 1976; Dickson and Green, 1970; Green, 1979; Grinnell, 1963; Henson, 1969; Hime, 1967; Ladhani and Thies, 1968; Longnecker et al., 1974; Pye, 1967; Racey, 1987; Suga, 1964; Wallach and Boever, 1983). Today, however, the anesthesia of choice for all bats is isoflurane. Helliwell (in litt.) does not recommend injectable anesthetics for bats, as their small size offers a very low margin of safety.

Hypothermy has been used to immobilize bats for surgical procedures; hypothermy does not induce analgesia, and therefore should be avoided for surgery.

SELECTED PATHOLOGICAL DIAGNOSES
1986 - Big Brown Bat (Eptesicus fuscus) - handraised pup, captive 7 wks. - died - urinary calculus; chronic ulcerative cystitis; chronic interstitial nephritis.

1986 - Evening Bat (Nycticeius humeralis) - handraised pup, captive 3 yrs., 2 mos. - died - lymphosarcoma.

1987 - Big Brown Bat (E. fuscus) - handraised pup, captive 9 yrs. - surgery at 4 months of age - calcinosis cutis circumscripta (FIG. 94).

Figure 94.   Calcinosis cutis circumscripta (arrow) on the wing of a big brown bat (E. fuscus) (photo courtesy of Gwen C. Choi-Roesel, Cold Spring, KY).

1987 - Big Brown Bat (E. fuscus) - handraised pup, captive 1 yr., 3 mos. - died - generalized vascular mineralizations; chronic interstitial nephritis.

1987 - Hoary Bat (Lasiurus cinereus) - wild caught adult, captive 2 wks. - died - acute pneumonitis.

1987 - Red Bat (L. borealis) - wild caught adult, captive 10 days - died - rabies; pulmonary congestion.

1987 - Red Bat (L. borealis) - handraised pup, captive 9 mos. - died - chronic diffuse interstitial pneumonia; hepatic lipidosis; acute mild multifocal necrotizing hepatitis.

1988 - Black Velvety Mastiff Bat (Molossus ater ater) - wild caught adult, captive 2 yrs., 3 mos. - died - glomerulotubular nephropathy; monocytic enteritis; purulent stomatitis.

1989 - Red Bat (L. borealis) - wild caught adult, captive 3 days - died - severe intestinal coccidiosis; focal hemorrhagic pneumonia; intestinal parasitism (cestodes).

1991 - Short-tailed Fruit Bat (Carollia perspicillata) - captive born, age unknown - died - lymphoid peribronchiolitis; focal myocardial hemorrhage.

1991 - Yellow Bat (L. intermedius) - handraised pup, captive 3 wks. - died - purulent necrotizing hepatitis; chronic purulent osteoarthritis.

1991 - Big Brown Bat (E. fuscus) - handraised pup, captive 9 yrs. - died - multifocal granulomatous pneumonia (undetermined etiology); mild diffuse interstitial nephritis.

1991 - Red Bat (L. borealis) - handraised pup, captive 1 yr. - died - epidermal hyperkeratosis; diffuse hepatocellular glycogen loading.

1993 - Red Bat (L. borealis) - mother-raised pup, captive 25 days - died - multifocal myocardial mineralization.

1993 - Red Bat (L. borealis) - handraised pup, captive 2˝ mos. - died - mild multifocal nonsuppurative interstitial nephritis and tubular necrosis with intratubular coccidian parasites.

1993 - Big Brown Bat (E. fuscus) - handraised pup, captive 1 yr. - died - early hydronephrosis; interstitial pyelonephritis; purulent cystitis; purulent sinusitis.

1993 - Big Brown Bat (E. fuscus) - handraised pup, captive 4 yrs. - died - oxalate toxicosis.

1994 - Big Brown Bat (E. fuscus) - wild caught adult, captive 9 yrs., 6 mos. - died - moderate hepatic lipidosis; acute multifocal subcutaneous hemorrhage.

1994 - Big Brown Bat (E. fuscus) - handraised pup, captive 3 yrs. - surgery at 3 years of age - focal severe chronic periostitis and periosteal cartilagenous/connective tissue proliferation (FIG. 95); chronic necrohemorrhagic cellulitis.

Figure 95.  A) bat wing before surgery;  B) bat wing after surgery.  Diagnosis was focal severe chronic periostitis and periosteal cartilagenous/connective tissue proliferation, and chronic necrohemorrhagic cellulitis (photo courtesy of Allpets Clinic, Boulder, CO).

1995 - Red Bat (L. borealis) - handraised pup, captive 1 yr. 6 mos. - died - chronic necrotizing cellulitis with intralesional bacterial cocci; multifocal lymphoplasmacytic cholangiohepatitis and interstitial nephritis.

EUTHANASIA
The word "euthanasia" is a combination of two Greek words meaning "good death." Euthanasia is the procedure of killing rapidly and painlessly. The killing techniques, therefore, should result in rapid loss of brain function, or more specifically, central nervous system (CNS) depression and insensitivity to pain.

Lollar (1994) and other workers (as reported by Routh, 1991) advocate putting bats in a refrigerator until torpid and then transferring them to a freezer. Stebbings (pers. comm. to Routh, 1991) states that this method is inhumane; a view shared by the American Veterinary Medical Association. As the bat's body temperature approaches freezing, the animal awakes from torpor in an attempt to find a warmer environment (Davis and Reite, 1967; Hock, 1960; Mumford, 1958). Bats placed in freezers are, of course, trapped and ultimately freeze to death.

The euthanasia method used to kill bats depends on several factors, including the number being killed, reason for killing, and effects on the person performing the act. Any technique, must result in death without anxiety, panic or pain. Thus, any prior restraint techniques, also must not precipitate anxiety, panic or pain. The technique must insure rapid loss of consciousness and death. Methods of euthanasia must be safe for the operator and other personnel, simple, and maintenance free (i.e., minimizes sanitation problems and environmental contamination). For the purpose of this book, the euthanasia techniques discussed below will encompass practical, humane, and relatively safe (to the handler) methods of killing bats, using acceptable methods published by the American Veterinary Medical Association's (AVMA) 1993 Panel on Euthanasia.

Inhalants
Gaseous anesthetics and carbon dioxide (CO₂) gas are acceptable inhalants for euthanizing small mammals. Preferred gaseous anesthetics include halothane and isoflurane. Unacceptable gaseous methods include cyanide because of extreme toxicity to humans, and chloroform, which due to known hepatotoxicity and suspected carcinogenic properties, is also hazardous to humans. Air embolism is also unacceptable because it may produce convulsions, opisthotonos, and vocalization. Decompression, as a means of euthanasia, should be avoided (see AVMA, 1993). Gaseous anesthetics may be unsuitable if toxicological studies are to be undertaken.

Carbon dioxide at a concentration of 60-70%, with a 5-minute exposure time, appears to be generally optimal for euthanasia (Glen and Scott, 1973; Jaksch, 1981). CO₂ is inexpensive, nonflammable, and poses minimal hazard to personnel when used with properly designed equipment. Additionally, it does not distort cellular structure (Feldman and Gupta, 1976). A disadvantage of CO₂ is that some animals have an extraordinary tolerance for it. Hansen et al. (1991) reported that 70% CO₂ induced unconsiousness in mink, but did not kill them. Bats also may have a high tolerance for CO₂. Although Lollar (1994) stated that CO₂ does not kill bats, Racey (1987) reported it successful. In the event carbon dioxide gas does not kill a bat, it may be used to induce unconsciousness prior to cervical dislocation, cranial concussion, or decaptitation to insure death.

Euthanizing with CO₂ is best done with compressed gas from a cylinder, rather than other sources such as dry ice or CO₂ from a fire extinguisher because the rate of flow to a gas chamber can be regulated: the flow-rate should displace at least 20% of the chamber volume per minute.

Non-inhalant Pharmaceuticals
All barbituric acid derivatives used for anesthesia are appropriate drugs for euthanizing bats, although these anesthetics may leave the body unsuitable for toxicological studies. Unacceptable injectable agents include strychnine because it produces violent convulsions and presumably painful muscle contractions, nicotine, magnesium sulfate, potassium chloride, and all neuromuscular blocking agents such as tubocurarine, gallamine, decamethonium and succinylcholine; when used alone, these drugs all cause respiratory arrest before unconsciousness, so the bat may perceive pain after it is immobilized.

Injectable agents can be administered intraperitoneally. I have also euthanized bats humanely by delivering injectable agents subcutaneously.

Physical Methods
Although stunning alone is an unacceptable method of euthanasia (AVMA, 1993), it is suitable in combination with cervical dislocation, cranial concussion or decapitation. Rather than stunning, hibernating bats may be refrigerated to induce torpor, then the relatively immobile bat can be killed by one of these methods. For cervical dislocation, Walsh and Stebbings (1988) suggested laying the bat in question on a hard surface, then placing a pencil across the neck and firmly pressing down. If decapitation is employed after hypothermia, the AVMA recommends placing the severed head immediately in liquid nitrogen. Where the intact head is required for rabies testing, cranial concussion is unsuitable.

Unacceptable physical methods published by the AVMA include drowning, exsanguination and freezing.

NECROPSY PROCEDURES
The concepts of acceptable veterinary and husbandry practices do not end with the death of a bat. Even if a veterinarian is not immediately available to perform a necropsy, one can still preserve tissues for histological examination. FIGURE 96 shows the necessary materials to perform a necropsy. In preparation for such 

emergencies, have on hand 1 gal. or more of 10% formalin (mix 1 part 37% formaldehyde with 9 parts water) and as many pint-sized jars as there are captive bats. Upon discovering a dead bat, place it on its back and with a razor blade or sharp-pointed scissors make a midline incision through the skin from the animal's neck to its genitalia, and move the skin away from the midline to expose the internal organs. Place the bat into a pint jar and fill the jar with 10% formalin. Secure the jar cap with tape and place it in a zip-lock plastic bag. Deliver the formalin-fixed tissues, with the following information, to a veterinarian.

Figure 96.  Materials necessary for performing a necropsy on a bat (photo courtesy of Gregory C. Greer, Marietta, GA).

* Owner's name, address and telephone number.
* Bat's given name, species, age and sex.
* Number of bats in same cage (or exhibit).
* The number affected and/or lost.
* Feeding history.
* Date and time of death if known, or date and time bat was found
dead in cage.
* Date and time animal was fixed in 10% formalin.
* Treatment and response if applicable.
* Behavior of animal prior to dying.
* Other important information.

Never freeze a dead bat unless otherwise instructed by the veterinary practitioner performing the necropsy. Freezing causes the body's cells to rupture and vital histological information will be lost in the process. Postmortem examinations should be performed immediately after the death of a bat to minimize autolysis (self-destruction of tissues).

Taxidermic specimens (FIG. 102, Chapter 11) and articulated skeletons can enhance educational programs. To protect the artisan preparing a specimen, brain tissue can be withdrawn through the foramen magnum via a hypodermic needle and a sterile syringe (Greenhall, 1965). The brain tissue then may either be left in the syringe or transferred to a sterile vial and delivered to a laboratory for rabies testing. Store the bat in a freezer while awaiting laboratory results.

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Bats In Captivity was adapted for the web
by Tamara Romaine

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