Exotic Pets 5e

Sample chapter fromBSAVA Manual of Exotic Pets 5th edition Edited by Anna Meredith and Cathy Johnson-Delaney © BSAVA 2010 www.bsava.com Specialist keepers may also keep more unusual araneomorph species such as Argiope or Nephila orb web spiders free in a room. Despite this large number of species. The largest species is A. with more than 100 species available in the pet trade from time to time.g. Spiders There are approximately 900 species of Theraphosi­ dae (tarantula) spider. land hermit crabs. Giant African land snails There are over 200 species of Achatinidae in sub­ Saharan Africa. (b) Mexican redknee tarantula. Dextral (right­handed) shells (a) 21. although individuals may be as long as 20 cm.1). While over 1 million invertebrate species have currently been described. the West African or Tiger snail.  compressus). Land hermit crabs The two most commonly kept semi­terrestrial land hermit crabs are the Caribbean or purple claw hermit crab (Coenobita clypeaus) and the Ecuadorian hermit crab (C.1 (b) are most common. (c) Imperial scorpion.  (a. Owners may be unaware that there are several common species.). For a more com­ prehensive review of invertebrate medicine readers are referred to Lewbart (2006).  Goliath birdeater  (Theraphosa blondi) and curly hair tarantula (Brachypelma albopilosum). These decapod crustaceans live up to 15 years in captivity.  Pterinochilus. The snails reach adult size within about 6 months and live approximately 5 years.1b). Some of the most commonly kept theraphosids include the terrestrial Mexican redknee tarantula  (Brachypelma  smithi. Ceratogyrus. and the Asian ornamental tarantulas (Poecilotheria  spp.  Chilean rose tarantula  (Grammostola  rosea). This chapter will concentrate on a small number of common terrestrial species. These have become an introduced agri­ cultural pest and are hence illegal in some countries.  Hysterocrates)  are  less popular but are kept. but are prized for their large size and striped appearance. also called the giant Ghana snail. as they remain in their webs. (a) GAL snail. Giant African land (GAL) snails are among the most commonly and easily kept pet invertebrates.  Figure 21. tarantulas and scorpions (Figure 21. which can have different husbandry requirements. and will aim to provide practical and useful information as a starting point for pet invertebrates.1a) from Kenya and Tanzania. The most common pet species is the East African GAL snail (Achatina fulica. fulica. with occasional reports of individuals living past 20 years of age.Chapter 21  Invertebrates 21 Invertebrates Romain Pizzi Introduction Pet invertebrates are occasionally presented to vet­ erinary surgeons and can be an interesting change from the more routine cases seen in exotic animal practice. only a handful are ever presented to veterinary surgeons dealing with exotic pets. despite their more (c) Some commonly kept invertebrates. Commonly kept spe­ cies include Giant African land snails.  achatina. and some estimate that it may be as high as 80 million. most sources esti­ mate the true number is likely to be between 6 and 10 million. Figure 21. Terrestrial African ‘baboon’ spi­ ders (e.) 373 . as well as arboreal species such as the pink­toe tarantula (Avicularia  avicularia)  from the Americas.b Courtesy of DL Williams. These are not as common as A. Adults average 10 cm in length. g. Mesh-top tanks are not preferred for terrestrial tarantulas as they have fine hooks on their feet. Brachypelma species. which may become stuck in the mesh and lead to injury or limb autotomy. which originates from North Africa. Serious hobbyists may keep sev­ eral hundred or even thousand spiders belonging to a large number of species.. In contrast. Housing General considerations • Land hermit crabs are gregarious and can be kept in large tanks if sufficient space and spare shells of various sizes are provided to prevent fighting and shell stealing. the Chilean rose (Grammostola rosea. particularly if overcrowded or food is scarce. Subadult tarantulas can be sexed by microscopic examination of the epygial region of shed cuticle for presence or absence of spermathecae. have hooked spurs on the tibial section of the first pair of legs. previously Phrixotrichus spatulata. only adults have cuticles that fluoresce. Flat tanks under 30 cm in height are therefore advisable. hence their popularity as pets. For this reason females are more desirable as pets. An awkward fall from as little as 30 cm can cause fatal opisthosoma trauma in heavy-bodied individuals. Biology Sexing Some pet invertebrates show sexual dimorphism. which are used to secure the female’s fangs during mating (Figure 21. adults commonly reach over 20 cm in length. Despite their impressive appearance imperial scorpions have weak venom and are relatively timid and reclusive in nature. Individuals can live up to 8 years in captivity. and owners may not be aware what species they in fact possess. Only females are long-lived. Indian stick insects (Carausius morostus) and some other phasmids will suffer from dysecdysis. while more severe condi­ tions will not respond to attempts at veterinary treat­ ment unless the captive environment is optimized.  smithi (Mexican redknee tarantula). Pet invertebrates are commonly kept by herpetologists and may therefore be treated by veterinary surgeons more accustomed to treating reptiles. and some health problems will resolve simply with husbandry changes. previously Grammostola spatulata) is often still referred to by its previous names in current publications. and so enclosures should be at least twice their maximum body length in size in all dimensions. • Imperial scorpions can be kept communally. Figure 21. Scorpions raised in isolation are more likely to try and predate each other. Scorpions The most commonly kept pet scorpion is the imperial or emperor scorpion (Pandinus imperator.Chapter 21  Invertebrates aggressive nature. which has increased their financial value. such as Brachypelma spp. are currently listed in Appendix II of CITES. and can be used to differentiate adult males. For example: the Mexican redknee and other Brachypelma species were previously referred to as Euthalus spp. There have been a large number of taxonomic revisions that further complicate litera­ ture searches. Exhibits often include an ultraviolet (UV) light source to demonstrate their blue-green fluorescence. such as Chilean rose tarantulas. so reliance should never be placed on common names. Husbandry Invertebrates are poikilothermic and hence highly dependent on environmental factors. e. Size Size is an important consideration. or they will predate each other. male Macleay’s spectres (Extatosoma tiaratum) have wings while the females do not. The male catches the female’s fangs with tibial hooks on the first pair of his legs and inseminates her with sperm stored in the distal pedipalps. • Tarantulas need to be housed individually.2). such as an ovipositor or genital claspers. There is an unfortunate tendency among pet shops and traders to make up imaginative names for taran­ tulas. for normal physio­logical 374     Chilean rose tarantulas mating. Adult males of many of the common pet tarantula species. including B. with males having a terminal instar once they moult to maturity. Arboreal species. for this reason several erroneous husbandry requirements based on herpetology have been reported in the literature. such as tem­ perature range and humidity. especially if youngsters are reared together or kept with their parents.1c). Adult female spiders can be extraordinarily longlived. If enclosures are too small.2 functioning. One of the largest scorpion species. provision of overly large enclosures can be a problem in large terrestrial tarantulas such as the Goliath birdeater. Infectious and non-infectious diseases are often a reflection of underlying environmental deficits. reports vary from 6–12 years in some African theraphosids to over 30 years in some New World terrestrial tarantulas.   (© Zoological Medicine Ltd. Many insects have distinct differences.) 21. such as Indian ornamental (Poecilotheria . Light misting is helpful for all species. cockroaches and mealworms. causes irritation and stress. they will rapidly metabolize their adipose bodies and will then hold little nutritional value for the tarantula or scorpion consuming them. Anorexic spiders may be tempted with waxworms. Fibres can also become entangled on limbs. Additional heating is required in colder climates. which should be thoroughly washed to ensure no pesticides are fed inadvertently. this may indicate environmental stress due to lack of a hide. A minimum/maximum ther­ mometer is useful for monitoring environmental tem­ perature stability. Imperial scorpions. as these insects will also metabolize their adipose bodies to liberate water if they become dehydrated. will aestivate by sealing themselves into the shell with a dried mucus film if conditions are too hot. This species hides in burrows in termite mounds when not hunting and it is important to provide hides to limit stress. depending on their size. Many specimens can be safely kept at fairly cool temperatures once accustomed to these. or if humidity is insufficient. Some tarantulas will accept small pieces of raw meat or chicken. These scorpions are often fed killed small mice in captivity. ground vibrations. or whole killed vertebrates such as mice. Scorpions will accept freshly killed prey. although they prefer live invertebrates. Substrate and hides Sufficiently deep sand should be provided for hermit crabs to burrow into for ecdysis. Water is best offered to arthropods such as spiders and insects in a shallow dish. provid­ ing a water bowl and reducing enclosure ventilation for species requiring higher humidity. easily provided by cuttlefish bone. High humidity also means enclosures need much more frequent cleaning to prevent food residue rotting and causing proliferation of Gram-negative bacteria that may cause disease. otherwise they will rasp other snails’ shells with the radula to obtain the calcium they need for continued shell growth. If starved. Humidity and water provision Arthropods need lower humidity than gastropods. GAL snails. but UV light is not actually needed for any normal physiological process. Wet cottonwool balls are not recommended as they quickly become soiled and can harbour heavy Gram-negative bacterial growth. and tarantulas are photophobic. Temperatures in the range of 20–30°C for tarantulas are recommended by most authors for normal growth and ecdysis rates. Blowing on these hairs.Chapter 21  Invertebrates regalis) and pink-toe tarantulas. despite their appearance. The common Brachypelma species and Chilean rose tarantulas do well at relatively low humidity and so are low mainte­ nance in terms of husbandry and cleaning. and excessive lighting may just lead to stress and anorexia. Lighting A fallacy to be found in some literature is that scorpions or other arthropods need a source of UV light. On post-mortem histology these specimens may show pathology of structures such as the Malphigian tubules. GAL snails do not readily accept powdered calcium on their food. as some species are photo­ phobic or nocturnal. Humidity is better provided by moistening the substrate. or bright lighting. Provision of dry bran is not sufficient. The heat mat should not be inside the enclosure as some species will instinctively burrow into the substrate if too warm. are reclusive in nature due to their weak venom. and although breeders may claim faster growth rates with these diets. and especially important for A. Retreats and hides should be provided in most arthropod enclosures. Heating In many arthropods temperature stability appears to be more important than the provision of a precise temperature gradient. but sudden temperature drops from a heated environment to that same lower temperature can cause mortalities due to ‘cold stress’. If a captive scorpion is frequently raising its tail in threat displays. Invertebrates as food items When crickets and locusts are used as food items. but unfortunately there is little precise information on optimum temperatures for most common terrestrial pet invertebrate species. Adult scorpions fluoresce blue-green under UV lighting. Imperial scorpions are reported to prey mainly on termites in the wild. While some literature recommends misting taran­ tulas daily. Shelled gastropod molluscs such as GAL snails need a dietary source of calcium. Diet Snails Herbivores such as GAL snails should be offered a variety of fresh leafy vegetables. achatina. 375 . can be provided with high but narrow enclosures. and in practical terms mean that room temperatures are sufficient in many localities without additional heating. or misting. Tarantulas locate prey by detecting air current movements via their highly innervated and sensitive hairs. an entirely invertebrate-based diet is perfectly adequate. A ramp or small pebble will also allow prey insects such as crickets to escape rather than drowning and rotting in the dish. this is not advisable. and in captivity are commonly fed crickets. Occasionally an individual will moult on the surface. Arthropods Tarantulas are normally fed live invertebrates such as crickets and locusts. Small heat mats beneath part of the enclosures are often best. particularly A. and two or more scorpions may feed collaboratively on the same prey item. a simple separator made from a ring of a plastic bottle can be a useful barrier to prevent injury from other crabs without risking damage by handling and moving the moulting crab itself. Scorpions are nocturnal. achatina. but these are not part of their natural diet in the wild. it is important to provide them with food and water for 48 hours before being offerred as food. ) 21. The youngsters venture off their mother’s back as they grow.3) and she will kill prey for them. They will ride on their mother’s back (Figure 21. eventually dispersing and becoming independent. The hardening or scleritization after ecdysis is mediated by hydrophobic phenolics. with the thumb and middle finger between the second and third pairs of legs on either side (Figure 21.4). as this may contain eggs. due to abrasive damage to the gastrointes­ tinal tract. sometimes for several months. Tarantulas can also be gently pinned to the substrate by applying finger pressure or using a pencil. forced calcium supplementation of food in some insects will cause decreased survival and fecundity. Tarantulas may be gently encouraged into the hand with a fine artist’s paintbrush. which is embedded in a mix of various proteins. Although some arboreal species (Avicularia and Poecilotheria) have been kept together in large communal enclosures. For this reason tarantulas should always be handled over a table. Asian taran­ tulas and African baboon spiders do not have this defence mechanism. cannibalism does still occur and thus is not advised. into their exoskeletons. Trauma is a common cause of captive spider deaths. that is it will produce fertile eggs without a male being present. and are cared for by the mother. Spiders Many New World theraphosids such as the Mexican redknee and Chilean rose tarantula rely for their pri­ mary defence on barbed irritant ‘urticating’ hairs that are kicked off from their dorsal opisthosoma into the face of potential predators. there are exceptions. A small number of people appear especially sensitive to these irritant hairs and can develop skin rashes or even respiratory distress on exposure. Other arthropods do not. While many invertebrates will form noncalcified eggs. Male tarantulas are only briefly introduced into the female’s enclosure for breeding attempts (see Figure 21. over the strong rigid cephalothorax carapace. In fact. Switching off enclosure heating 12 hours before handling may be helpful with some Old World taran­ tula species. latex gloves are a sensible precaution. Any aggressive response will indicate that the tarantula is unlikely to tolerate gentle handling attempts. Care should always be taken when changing the substrate. The eggs are large (3–5 mm in length) with a calcified shell and are buried in the substrate. They can produce up to 200 eggs five times a year. and so will bite much more read­ ily in defence. and the stronger spiderlings will predate the weaker ones. do not need calcium sup­ plementation. and hence a polysaccharide carbohydrate. It is recommended that tarantulas be housed individually as cannibalism can occur. . as is sometimes advocated. containing both ovaries and testes.Chapter 21  Invertebrates Calcium supplementation The need for calcium supplementation in all inverte­ brates is a common fallacy. phasmids and insects can be a serious problem in captivity and culling may be needed to keep numbers manageable. The majority of arthropods. This can also be used to assess the individual’s temperament and mood before handling. 376     Newly emerged scorpions ride on their mother’s back for several months before becoming independent and dispersing. but placing individuals in the refrigerator for 30 minutes. Arthropods The Indian stick insect is parthenogenetic. by gently and repeatedly stroking the first pair of legs. When handling New World tarantulas. predominately calcium car­ bonate. a long-chain polymer of N-acetylglucosamine. The tarantula can then safely be grasped and lifted. Snails GAL snails are hermaphrodites. Spiderlings are commonly left together after hatching for the first few moults. Differing proportions of chitin lead to differ­ ences in rigidity and flexibility between species. The arthropod exoskeleton consists of a combination of chitin. even in peer-reviewed literature. Breeding Uncontrolled breeding of snails. sperm can be stored viably for over a year. The mother will defend them and will be more aggressive to handling attempts during this period.3 Handling and restraint Handling and restraint needs to be gentle in order not to damage delicate invertebrates and also not to allow specimens such as tarantulas or scorpions to injure the handler. An awkward drop from as little as 20 cm can rupture the opisthosoma of a large terrestrial tarantula. such as some large beetles and GAL snails. and even between the layers of the cuticle. All scorpions give birth to live young. Only some crustaceans and myriapods (millipedes) will incorporate minerals. which produce eggs with a mineralized shell. as well as anatomical regions.   (© Zoological Medicine Ltd.2) and swiftly removed after this has occurred. can result in mortalities. Newly emerged scorpions are vulnerable and unable to fend for themselves. such as pet scorpions and tarantulas. 5 Scorpions Safe handling of imperial scorpions is accomplished by grasping the tail dorsoventrally with padded forceps (Figure 21. Radiography can also be useful in shelled molluscs. as they are susceptible to trauma at this time. and very little soft tissue differentiation is evident even in large specimens. rather     Handling an imperial scorpion using padded forceps to grasp the tail. This is an African species and lacks irritant hairs. (© Zoological Medicine Ltd. such as anorexia and reluctance to move. their cuticle consists of proteins. to evaluate severe shell cracks after trauma and to help plan repairs to provide adequate stabilization. and should not be disturbed or handled during this process. Dead spiders are normally found in an upright position with their legs in flexion beneath them. The water bowl can be emptied prior to transportation to prevent spillage.) 21.6 21. as the majority of health problems encoun­ tered in pet invertebrates will be husbandry-related. A small amount of water is all that is needed.7 Ultrasonography is particularly useful for GAL snails. and either an abnormally huddled posture or standing on ‘tip toes’. which may be grasped laterally at the distal third with padded forceps. or simply placing the specimen in a clear-walled container. History Safe handling of a Pterinochilus tarantula. Ultrasonography Ultrasonography can be useful. A thorough history – with emphasis on husbandry – is essential. (© Zoological Medicine Ltd.) 377 .6). normally undergo ecdysis on their back. as the legs have flexor muscles only and rely on haemolymph pressure for extension.) 21.   (© Zoological Medicine Ltd. Snails are less likely to retract when water is used. Imaging Tarantulas.5) and should not be handled. Tarantula keepers often notice Panagrolaimidae-infected tarantulas (see later) first by the distinctive behavioural changes they demon­ strate. Radiography Radiography is of very limited value in invertebrates such as arthropods. Cuttlefish are an exception: traumatic fractures of the cuttlebone and resorption lesions associated with bacterial infections may be visualized radiographically. Clinical examination A macroscopic visual examination can be aided by the use of a low magnification stereomicroscope. will allow gross visual examination.Chapter 21  Invertebrates Diagnostic approach If individuals are kept in small enclosures these should ideally be brought into the veterinary surgery. as the copious mucus secreted by the gastropod foot is a perfect natural coupling gel.7). Some other more venomous scorpion spe­ cies have a more muscular tail.4 Tarantulas laying on their back are normally undergoing ecdysis (Figure 21.) 21. Flattening arthropods such as scorpions with clear plastic sheeting on to a plate of glass.   so does not necessitate latex gloves. Behavioural changes can be an important indicator of some conditions. such as this Mexican redknee. such as GAL snails. they cannot twist the distal tail to sting to the side. especially in GAL snails (Figure 21. (© Zoological Medicine Ltd. (© Zoological Medicine Ltd. while individuals could be identified. Similarly. the author has not examined a millipede post mortem that has not had numerous gastrointestinal nematodes present.10). as it provides magnification of these small patients. A strong pure culture of a Bacillus species. Endoscopy Endoscopy is a useful diagnostic modality in inverte­ brates. millipedes com­ monly have a high nematode burden on examination without showing clinical signs. Ultrasonography can also be useful in determin­ ing the origin and thus prognosis of a prolapse (see later).9). of which there are numerous entomopathogenic and toxin-producing species. (© Zoological Medicine Ltd. pharynx and cranial digestive tract. fungal and protozoal infections and lesions. Some arthropods such as tarantulas do not have discrete visceral organs that are amenable to ultra­ sound examination. Ultrasonography has. and endoscopy may even be useful in evaluating obstructive egg retention in large insects. Its most useful application is in determining if a deeply retracted snail is just in deep aestivation or. Faecal examination Faecal samples may yield protozoans such as Coccidia and gregarines. as well as developed eggs. without the need for microscopy. culture post mortem is often unrewarding. but interpretation of the significance of any organisms isolated can be difficult. however. Some entomopathogens are 378 Many arthropods will react to infections or trauma by forming melanized inflammatory nodules. which are a typical inflammatory response to trauma or infection in insects and many arthropods. are relatively easily visual­ ized. Prolapses could also be examined.8 Microbiology Bacterial and fungal culture can be performed on samples from lesions. but many insect species normally har­ bour a high gregarine parasite load asymptomatically in captivity (Figure 21. attempts at treatment by aspiration of the parasite have been unsuccessful and resulted in the spider’s death. Gregarine parasites in the gut of a desert   locust (Schistocerca gregaria).) 21. in fact.9 Cytology and haematology Standard stained and unstained cytology can be useful in identifying bacterial. and structures such as the oral radula. Small 7. Doppler ultrasonography has been reported to be useful in auscultating and monitoring heart rate in GAL snails (Rees Davies et al. Due to rapid gut breakdown and bacterial invasion after death. 2000). 2006). been used to screen tarantulas for the presence of large endoparasitic acrocercid larvae in the opistho­ soma (Johnson-Delaney.) 21. is more likely to be significant than a mixed culture. Endoscopic evaluation of oral discharges in tarantulas can allow differentiation of microscopic panagrolaimid nematodes from bacterial infection. or on oral or anal discharges.10 .5–10 MHz curvilinear probes will give good definition. The pulmonary sac can be examined for nematode or mite infections. Unfortunately.) 21. (© Zoological Medicine Ltd. Endoscopic view of the pulmonary sac via the pneumostome in an East African GAL snail. difficult to culture using standard veterinary techni­ ques. as well as melanization reactions and nodules (Figure 21.8) is easy and can help demonstrate to clients that the snails are not infected with Angiostrongylus cantonensis or parasitic mites. Endoscopic exami­ nation of the lung of pulmonate terrestrial snails via the pneumostome (Figure 21. dead..Chapter 21  Invertebrates than normal ultrasound gels which appear to irritate some specimens. currently precluding any meaningful clinical application. (© Zoological Medicine Ltd. this has only been seen in wild snails.) 21. and these do not require treatment. the diagnostic approach usually relies on post-mortem examination and sampling. but the emerg­ ing parasites usually pose little threat to other captive invertebrates outside their normal geographical range. it is better to take samples from live specimens than to use dead individuals. often indi­ cates environmental stress. Necropsy In a group invertebrate disease problem.10) may be helpful in demonstrating infection. and hence do not develop alopecia.13). result­ ing in an obvious bald patch (Figure 21. Blood smear from a tarantula. eggs or inflammatory melanization reactions. Such preparations can be examined for evidence of mites. and values vary with life stage and prox­ imity to ecdysis. There is no treatment for these fatal infections. a person would need to eat an infected GAL snail raw to contract the disease. A bald patch is clearly visible on the dorsal opisthosoma of this Mexican redknee tarantula. such as acrocercid spider-fly larvae and mermithid nematodes in tarantulas.11) and other invertebrates. which is typically bald. The hairs will not regrow. but stress should be addressed where needed.Chapter 21  Invertebrates There are some publications on haematology in tarantulas (Figure 21. Myriapods commonly carry a high load of mixed nematodes in the digestive tract asymptomatically. The green/blue respiratory pigment haemocyanin is contained in crystalline form in special haemocytes (cyanocytes) before being liberated into the haemolymph. such as excessive handling or viewers repeatedly disturbing the spider by tapping on the glass. many New World species of terres­ trial tarantula have urticating hairs on the dorsal and caudal aspects of their opisthosoma which they will kick off with their hind legs in the face of predators. and also with environmental tem­ peratures. Endoscopy of the pulmonary sac (see Figure 21. Although there is much written about zoonotic Angiostrongylus cantonensis nematode infections in GAL snails. presumed due to stress from viewers constantly banging on the glass of its enclosure.12 There are a large number of endoparasites. or viral destruction of adipose bodies in Lepidoptera.12) can demonstrate infections such as tracheal mites (Acarapis woodi) in honeybees which are visible in the respiratory tracheoles. and not in the UK.) 21.) 21. As gut breakdown and translocation of bacteria occur rapidly. that may be present in asymptomatic wild-caught individuals for months or even years. complete with its full complement of hairs. is thin and can be easily ruptured. (© Zoological Medicine Ltd. but sources often do not agree on nomenclature of cell types.13 Endoparasites Section of an insect tracheole viewed microscopically. but once a new moult occurs the spider will have a new appearance. Skin scrapes should not be performed on tarantulas with alopecia as the dorsal opisthosoma overlying the heart. Interpretation of invertebrate haematology is still in its infancy. The condition does not need treatment. Simple dissection of viscera immediately following euthanasia and wet mounting between slides (Figure 21. or when disturbed. Snails are infected through rat faeces. 379 . even starting before death. leading to fatalities. Asian tarantulas and African species do not have these irri­ tant hairs. Loss of these hairs in captivity. (© Zoological Medicine Ltd. Hair loss in tarantulas As noted above.11 Common conditions Only a small number of conditions in the most common pet invertebrate species can be briefly covered here. for more detailed information the reader is referred to Lewbart (2006). which also acts as a viral vector and causes colony die-offs. they appear to control the mites in the enclosure without irritating the spider. humpbacked flies (Phoridae) have been suggested as possible vectors. highly motile nematodes (< 0. which cause tissue necrosis on which the nematodes feed. The diagnosis can be confirmed by visualizing the small. Wood chip and bark sub­ strates are more likely to harbour mites.) Other mites are clearly pathogenic. which has been reported in the UK. such as Gromphadorholaelaps schaeferi.5–3 mm in length) in a sample of saline flushed over the mouthparts. minimal handling and euthanasia of all affected spiders is currently strongly recommended. While the mode of transmission is unknown. even if mortalities are not obvi­ ous. secondary infection of bite 380 Parasitic mites on a newly imported African dung beetle. (© Zoological Medicine Ltd. The infection manifests initially with anorexia and lethargy.Chapter 21  Invertebrates Saprophytic soil nematodes (and mites) may be found in the substrate and are not a concern. Death occurs after several weeks. rather than parasitic or host-specific. Since large specimens of Theraphosa blondi can have fangs in excess of 3 cm. An important consideration is that related nematode species have been demonstrated to cause a poten­ tially fatal zoonosis of deep anaerobic wounds. Hypoaspis miles. Recent work has also suggested that these nematodes may be related to those of beetles. but often indicate a need to clean the enclosure. several European countries. and potential spread in a collec­ tion. Mites Mites are a frequently reported problem in captive terrestrial invertebrates (Figure 21. The nematodes appear to have a symbiotic relationship with bacteria. Saprophytic mites are com­ monly encountered in high-humidity enclosures. the USA and Canada. removing visible mites with petroleum jelly/ultrasound gel on a cotton bud or fine artist’s paintbrush. Tracheal mites in a variety of insects may also cause decreased survival and fecundity. 21.) 21. and with anti­ microbials for the associated bacteria. with no effective treatment currently available. which progresses to a huddled posture. (© Zoological Medicine Ltd. and this has raised the possibility of mealworm beetles (Tenebrio molitor) acting as vectors. Oral nematodes of tarantulas Panagrolaimid nematodes appear to be an important emerging problem in captive pet and zoo tarantulas. mite removal with sticky tape. and applying a 1:200 dilution of ivermectin with a fine . This appears at first to be fluid macroscopically. lack of treatment options.14 All treatment attempts with different benzimid­ azole and avermectin anthelminthics. There is ongoing research and these guidelines may change within the next few years as more is learnt about these nematodes. Due to the possible risk. Saprophytic mites can occa­ sionally cause irritation and can cause hermit crabs to abandon their shell. that is sold to control fungus gnats and pest thrips has also been used successfully in large collec­ tions of tarantulas. A commercially available predatory mite. Some hostspecific mites are not particularly harmful. such as Varroa destructor in European honeybees. Many are saprophytic. depending on the affected species. A thick white discharge between the mouth and chelicerae may be noted. as mites without piercing mouthparts are not parasitic. Numerous other methods have been described.15 Panagrolaimid nematodes forming a white fluid-like mass under magnification on the mouthparts of a Goliath birdeater. but under endoscopic or microscopic magnification can be seen to consist of a mass of microscopic motile nematodes (Figure 21. and infections have spread between separate containers in a room. wounds is possible. a mite specific to Madagascan hissing cockroaches that feeds off food around the mouthparts. have so far been unsuccessful at even prolonging survival time. or where hygiene is poor. including: removing all substrates. Microscopy can sometimes be helpful. but this is not always clear.14).15). Many hobbyists routinely microwave non-flam­ mable substrates in order to prevent mite outbreaks. such as phasmids. when external fruiting bodies rapidly emerge and produce spores. Dysecdysis is relatively uncommon in adult scorpions. When the bursa copulatrix or dart apparatus pro­ lapses. It is essential to avoid the temptation to interfere or try to assist during ecdysis. In contrast. Signs of intoxication can include anorexia and decreased mobility. The second type of infection demonstrates visible fungal growth only after an individual’s death. Arthropods. If it is a recurrent problem in a collection. Trauma and dehydration Trauma (see Wound repair. but often there are no antemortem clinical signs. and irritants. as the arthropod cuticle is relatively water-resistant and the surface tension of water prevents it entering the narrow space between the new and old cuticle. in captivity. Egg binding Egg binding is occasionally seen in females. Digestive tract prolapses usually indicate severe systemic disease and are invariably fatal. New arrivals should always be quarantined in separate rooms to an invertebrate collection for 30 days. and there is a good prognosis. The new cuticle is soft and fragile to allow body expansion to occur. Good nutritional status and hydration are important in preventing dysecdysis. appear to be sensitive to fipronil toxicity due to its residual nature. plastic containers such as film canisters may be useful as temporary ‘pseudoshells’. scleritization takes place over the first few hours to days. despite being washed. Some other compounds appear less harmful than would be supposed: the author has used 1:200 dilutions of ivermectin topically on large scorpions and tarantulas to treat mites without any apparent ill effects. Hermit crabs out of shell It is not normal to find land hermit crabs out of their shell. or insufficient humidity. but care must then be taken not to apply this in the vicinity of the book lungs (or spiracles in insects) to avoid asphyxiation. There can be numerous causes. particularly tarantulas. ecdysis. such as mites. These commonly invade the coelom. attempting gentle removal with surfactants. multiplying with no external signs until the animal’s death. Dysecdysis Dysecdysis is a common problem in arthropods. Adding a surfactant such as household detergent can be useful. often due to poor environmental hygiene. which include: severe systemic illness. it is still advis­ able to apply cyanoacrylate adhesive to the site to prevent haemolymph leakage. stealing of the shell by another hermit crab (extra shells of a variety of sizes should be available in the enclosure). it is best to wait 12–36 hours until the new cuticle has hardened before attempting to trim retained cuticle away with fine scissors. Shells can be removed and boiled to kill mites. or inducing autotomy of affected limbs (see Autotomy. Misting during the actual ecdysis is often not particularly helpful. treated enclosures have killed spiders several months later. The majority of these are opportunistic infections. can be performed. enclosure temp­ eratures that are too warm. below) and resultant dehydration (see Rehydration. stress. Prolapses Prolapses are not uncommonly seen in GAL snails.20). but it may occur if treated vegetables are fed to herbivorous species. below) are common problems in pet invertebrates. this is another reason for veterinary surgeons to use latex gloves when handling patients. and attempting to remove this usually results in dismembering the patient by tearing the new fragile cuticle. Commercial flea and tick treatments. appear very sensitive to even household aerosols.16). Careful removal of the obstructed ootheca (capsule containing the eggs) is possible in affected large individuals such as cockroaches (Figure 21. and are an uncommon source of intoxication in pets. particularly tarantulas. and enclosures can be encircled with double-sided sticky tape to catch any mites leaving the enclosure. the old cuticle is hardened and strong. and usually indicates an entomopathogenic fungus. In severe cases. Many tarantulas will autotomize limbs safely during this period (see Figure 21. Poisoning Most modern dedicated agricultural pesticides are rapid-acting and non-cumulative. destocking for several months and fumigation may be needed before keeping can recommence. and respond well and rapidly to topical treatment with weak povidone–iodine. followed by careful removal of the membranes with a cotton bud. The first is most commonly seen in individual pets and manifests as visible fungal growth on the exoskeleton while the individual is still alive. Even if several limbs are trapped or distorted. Fungal infections Two basic types of fungal infection are seen in captive arthropods. below). it is possible that there may be an environmental problem such as lack of suitable or sufficiently deep ovipositing substrate. but a form can occur in newly emerged scorpions when embryonic membranes are desiccated and become trapped. These infections are very difficult to manage in collections once spores have contaminated a room. or incoordination and twitching. Moistening for several minutes on wet tissue paper. very occasionally. it may be replaced with a lubricated probe or moist cotton bud. household sprays.Chapter 21  Invertebrates artist’s paintbrush. Some species. depending on the compound. Care should be taken when using containers previously used for snakes that fipronil was not used to treat snake mites. and fumigation of nearby properties are more problematical. In some cases affected individuals may show colour changes or behavioural abnormalities shortly before death. 381 . If sufficient shells are not available. originating from the Asian giant honeybee (Apis dosata). now problematic in the USA. since their recognition in the UK in 1992 they have become endemic and so are no longer notifiable. The Office International des Epizooties (OIE) lists Varroa destructor and tracheal mites (Acarapis woodi) of bees as Notifiable. where it naturally occurs on the Asian honeybee Apis cerana. viral sacbrood.16 Notifiable Diseases Veterinary surgeons dealing with honeybees (Apis  mellifera) should be aware that. and fungal chalkbrood (Ascosphaera  apis).Chapter 21  Invertebrates This false death’s  head cockroach  (Blaberus discoidalis) suffered  dystocia because the  ovipositing substrate was too  shallow. Canada and Australia (a) (b) (a) The pathognomic ropey thread seen in  American foulbrood in the European honey bee. particularly temperature and humidity. such as the protozoan Nosema  apis.) 21. These are: • • American foulbrood (Figure 21. The mite feeds on adult European honeybees and brood. along with several diseases of crustaceans and molluscs of commercial concern.17b). Infested colonies eventually die out if not treated. Lightly infected hives may be treatable with oxytetracycline administered by licensed inspectors. In the UK. a bacterial disease caused by Melissococcus plutonius. . Supportive care Supportive care in pet invertebrates usually consists of correcting underlying environmental problems.17 382 •  Tropilaelaps spp.  (Courtesy of DL Williams. and further offers testing and monitoring of suspected incidents of pesticide intoxication of bees with the Wildlife Incident Unit. The unit also offers treatment advice. a bacterial disease caused by Paenibacillus larvae var. and the correction of fluid deficits. The United Kingdom includes one further Notifiable Disease: • European foulbrood (Figure 21. The parasite originates from Asia. While Varroa  destructor mites are the most economically important health problem of honeybees. The large ootheca was  removed manually to relieve the  obstruction. as well as acting as a vector for viruses such as deformed wing virus (DWV).) 21. Further difficulty in control has arisen with the recognition of pyrethroid­ resistant mite strains in the UK since 2001.17a). causing weakness. the amoeba Malpighamoeba  mellificae. (© Zoological  Medicine Ltd. there are currently three Notifiable Diseases in the European Union according to EC Directive 92/65/ EEC. larvae The small hive beetle (Aethina turnida). the National Bee Unit offers diagnostic testing of these as well as other common bee diseases. at time of going to press. an African species.  (b) European foulbrood leaves a dry scale in the cell. mites. In contrast to arthropods.08% sodium pentobarbital at 27°C for 30 minutes. but Joosse and Lever (1959) found this method caused mortalities. While this technique may or may not be practical in a veterinary clinical setting. pulmonate terrestrial snails appear very sen­ sitive.08% sodium pentobarbital and 0. Rehydration Snails If dehydrated or kept under dry conditions GAL snails will retract and seal themselves into their shell and aestivate. this can usually be accomplished using a small-headed pulse Doppler probe to auscultate vascular flow (see Figure 21. followed by a shallow bath of both 0. O’Brien (2008) recommends using sterile water rather than saline in phasmids as their haemolymph contains little sodium. such as GAL snails. Fluids may be administered into (or haemolymph sampled from) the heart. Girdlestone et al. Tarantulas have a closed arterial and open venous system. and the author has inadvertently killed GAL snails with what would be normal volatile anaesthetic concentrations in other species.9% physiological saline. (© Zoological Medicine Ltd.18). Zachariah and Mitchell (2009) recommend shallow tricaine methane sulpho­ nate (MS-222) at 100 mg/l. (1989) found effective dose 50 (ED50) concentrations for reversible anaesthesia.) 21. where the heart lies (Figure 21. Sodium pentobarbi­ tal baths were found to provide insufficient anaesthesia by Joosse and Lever (1959).Chapter 21  Invertebrates Drug administration Therapeutic usage of medications in pet invertebrates is anecdotal at present. Needle puncture sites should be sealed with cyanoacrylate adhesive to prevent haemolymph leakage. A relatively reliable and safe method for inducing surgical depth anaesthesia across numerous different pulmonate snail species has been described by Mutani (1982). as well as differentiating aestivating from dead individuals. found just beneath the shell rim in the mantle. As the cuticle is inflexible. Revival occurred within 60 minutes of being placed in normal water. Rehydration is accomplished by placing the snail in a shallow tray of warm water. In more severe cases.3% MS-222. as extension of appendages is dependent on haemo­ lymph pressure. intrahaemolymph injections of sterile isotonic fluids may be performed using a 30-gauge insulin needle and syringe. it is advisable to seal all needle puncture sites with tissue adhesive.19 383 . Water appears to be more effective than 0. including aquatic species. If treating arthropods for dehydration secondary to suspected trauma or haemolymph loss. If using a bath for terrestrial gastropods such as GAL snails. It can be difficult to tell whether a snail is dead or simply deeply retracted and aestivating. Anaesthesia and analgesia O’Brien (2008) provides a detailed review of anaes­ thesia in invertebrates.19). which appear resistant to volatile anaes­ thetics. due to the increased osmotic gradient. The easiest treatment in most cases is to place the cephalothorax of the spider in a very shallow dish of water. and fluids will be effective even if the heart is missed. judged on loss of whole body withdrawal reflex.09% v/v isoflurane. Arthropods Severely dehydrated spiders are unable to move. the bath should be sufficiently shallow so as not to cover the pneumostome (opening to the lungs). Haemolymph is pale and often difficult to see otherwise. Most spiders will rehydrate over a few hours. to be only 0. and 1. Veterinary surgeons are referred to Lewbart (2006) for further information. (© Zoological Medicine Ltd. which in emerged snails should not cover the pneumostome entrance to the lung just beneath the lip of the shell. Snails were placed in shallow baths of 0. anaesthesia of pet snails should be regarded as higher risk than that of arthropods.18 Scorpions can similarly be injected via the soft pleurite membranes between the hard dorsal and ventral plate-like tergites. and this information conveyed to owners when consent is sought. with complete surgi­ cal depth anaesthesia occurring within 20 minutes. Care must be taken not to sub­ merge the book lungs on the ventral opisthosoma. Snails Practical anaesthesia of some gastropods. into the dorsal midline of the opisthosoma.) 21.19).83% v/v halo­ thane. Anaesthetic depth is judged on foot and whole body withdrawal reflexes. and it is possible to monitor heart rate by means of a Doppler ultrasonography probe (Figure 21. which lies in the dorsal midline of the opisthosoma in tarantulas. this can last for several months. to keep individuals on paper towels for 48 hours instead of the normal substrate to detect any signs of continued leakage. appears to be difficult. it is advisable Doppler ultrasonography can be used to auscultate vascular flow and monitor anaesthesia in gastropods. but this may affect feeding. but induction can take over an hour and concentrations recommended vary widely.20 Crustaceans are problematical to anaesthetize. by rapidly jerking the coxa dorsally while the grasped femur retains its position. and will return to normal size and appearance within 2–3 ecdyses. The remaining muscles insert on thickenings of the joint capsule (sclerites). Grasping more distal limb segments does not usually lead to the spider auto­ tomizing its leg. lidocaine and xylazine via the arthrodial limb joint membranes has been described (Lewbart.03 to 1 ml/l. The coxal apodeme fractures and the joint membrane ruptures dorsally under the tension. Autotomy Tarantulas and other spiders are able to perform limb autotomy (Figure 21. can be safely anaesthetized with 4–6% isoflurane concentrations. it is unknown how invertebrates interpret noxious stimuli. Limb amputation Limb amputation is fairly easily accomplished in most arthropods. Foelix (1996) . and retracts into the coxa.) 21. escape if trapped by dysecdysis.20). and especially in the proximity of the tiny oral cavity in tarantulas and the surrounding filtering hairs. (© Zoological Medicine Ltd. and may be needed in cases of trauma where there is uncontrolled haemolymph loss. Appropriate anaesthesia should prevent any response to noxious stimuli and therefore meet the requirements for analgesia in invertebrates. blockage of which will result in inability to suck up liquid food. Crustacean neurotransmission depends on peptides and hydroxytryptamine glutamate.) 21. The limb will usually regenerate during the next ecdysis. This evolved to allow ani­ mals to discard a badly damaged limb. The arthropod cuticle is brittle and not easily sectioned without fragmenting. scorpions and insects. and spiders have been lost up to a month later from this. taking up to 20 minutes in tarantulas. 2006) but may result in limbs being autotomized. which predominately use anaerobic mus­ cle activity and rely on passive diffusion of gas via the book lungs. Autotomy is a voluntary act and can­ not be performed with the spider anaesthetized. A double anaesthetic chamber prevents the patient escaping up one of the tubes. 384 This shed tarantula cuticle contains a trapped limb that the spider had autotomized. it is best to apply this in several individual layers. or seal spiracles or book lung openings. Clove oil has been used in some aquatic crustaceans. While hypothermia is sometimes used to facilitate handling. Induction can be slow. insert­ ing on the trochanter. (© Zoological Medicine Ltd. 1995). Wounds or stumps of amputated limbs should be sealed with tissue adhesives. MS-222 is not particularly effective in many crustaceans. so incisions should be made in the joint membranes.5% v/v (Ingle. from 0. which in vertebrates would be perceived as pain. or survive an unsuccessful mating attempt. such as tarantulas. Halo­ thane was effective in anaesthetizing freshwater crayfish in under 15 minutes using concentrations of 0. Some invertebrates are particularly sensitive to rapid temperature changes and ‘cold stress’. The usual autotomy site is between the coxa and the tro­ chanter. but usually the vet­ erinary surgeon needs to snap the femur rapidly upwards.Chapter 21  Invertebrates Arthropods Most common pet arthropods. Care should be taken around the base of appendages not to glue other limbs. It is strongly advised to apply cyanoacrylate adhesive after any autotomy. limiting haemolymph loss. This tarantula is demonstrating the loss of righting reflex. The pedipalps may also be autotomized. Induction is more rapid in insects. and contraction of these function to pull the wound edges closed.21). Anaesthesia is judged on loss of righting reflex. This may be per­ formed in a double anaesthetic chamber to prevent the patient escaping up the tubing (Figure 21. Analgesia Currently. as there is a risk of haemorrhage starting at a later point. Injections of anaesthetic drugs such as keta­ mine. The spider may shed the limb itself. Common surgical procedures It comes as a surprise to many veterinary surgeons that surgical procedures are indeed possible in invertebrates. in addition to more orthodox neurotransmitters. Only the gracilis muscle traverses the autotomy site.21 Autotomy can be induced by firmly grasping the femur segment of the limb. This generally detaches easily. which contain spiracles and a tracheolar respiratory system. this is believed to cause immobilization rather than any loss of sensation and is therefore not considered humane anaesthesia. and their response to anaesthetic agents can vary in comparison with other species. Zeitschrift für Parasitenkunde 68. through the 1993 amendment. when all the appendages regenerated. otherwise there is little sense in a pet invertebrate owner approaching a veterinary surgeon. MA Mitchell and T Tully. (2008) The importance of hive health in apiculture from a veterinary perspective. Commercial ‘superglue’ gels do not appear to be usable. and these have healed by the following ecdysis. or freezing. Cambridge. Hauppauge. Louis Pizzi R. ed. as they tend to seep into cracks. alcohol or formalin). pp. 11–38. St. 26–33. Malabar. 2nd edn. UK Vet 13(8). 1991).Chapter 21  Invertebrates reported a specimen where all the legs and pedipalps were automomized. in the author’s experience some small spiderlings and insects will demonstrate frantic activity for over 5 minutes. FL Girdlestone D. Wound repair Molluscs Radiography can help in determining the extent of shell damage. Blackwell Publishing. acting as a foreign body and preventing healing from occurring. Large or lacerated wounds in the tarantula opistho­ soma have been repaired using a small patch of micro­ pore tape covered with several layers of tissue adhesive. M Fowler and E Miller. Amsterdam. Journal of Small Animal Practice 28. Barron.279–295. Potters Bar Johnson-Delaney C (2000) Exotic Companion Medicine Handbook for Veterinarians. Carlsbad. San Diego Williams D (2002) Invertebrates. Cruikshank SG and Winlow W (1989) The actions of the volatile general anaesthetics on withdrawal responses of the pond snail Lymnaea stagnalis. and this method is hence not recommended unless animals are first anaesthetized. 2. ed. ed. Louis 385 . Ames. While conscious immersion in alcohol is commonly used by entomologists in the field. large tarantulas). Louis Pizzi R (2002) Induction of autotomy in Theraphosidae spiders as a surgical technique. pp. UFAW. resulting in larger wounds and the taran­ tulas’ death. The author has found tissue adhesives or commercial cyanoacrylate ‘superglue’ to be the best trauma repair method in arthropods such as spiders. UFAW. Veterinary Invertebrate Society Newsletter 2(18). Exotic DVM 5(2). Tissue adhesives are not suitable.101 Reichling SWB and Tabaka C (2001) A technique for individually identifying tarantulas using passive integrated transponders. St. Shell repair in gastropod snails is performed by cleaning and apposing fragments.g. 18–20 Rees Davies R. Some owners may want the cadaver for display (e. In: Anaesthesia of Exotic Pets. while in other cases post-mortem histology or bacteriology may be desired. Proceedings. pp. The method of euthanasia is also determined by what the cadavers will be needed for. 229–239 Foelix RF (1996) The Biology of Spiders. In: BSAVA Manual of Exotic Pets. pp. Octopus vulgaris. 8–9 Mutani A (1982) A technique for anaesthetising pulmonate snails of medical and veterinary importance. NM Schultz SA and Schultz MJ (1998) The Tarantula Keeper’s Guide. 2–6 Pizzi R (2008) Disease management in ex-situ invertebrate conservation programs. Chitty JR and Saunders R (2000) Cardiovascular monitoring of an Achatina snail using a Doppler ultrasound unit. It is strongly recommended that crustaceans are pithed during euthanasia. Euthanasia is usually practically performed by using anaesthetic agents.145–149 Lacey L (1997) Manual of Techniques in Insect Pathology. An exception is the UK Animal (Scientific Procedures) Act 1986 which. 152. FL Johnson-Delaney CA (2006) Use of ultrasonography in diagnosis of parasitism in goliath bird eater tarantulas (Theraphosa blondi). followed by pithing. The same technique has been successful in scorpion dor­ sal mesosoma or metasoma wounds. References and further reading Boyle PR (1991) The Care and Management of Cephalopods in the Laboratory. LA Longley. Integument wounds in cephalopods have been reported to heal well with standard monofilament absorbable sutures (Boyle. A Meredith and S Redrobe. and covering the cracks with micropore tape followed by an epoxy resin repair (Lewbart and Christian. 117–118 Schultz SA and Schultz MJ (1996) A Mechanical Mom for Tarantulas. Krieger. British Veterinary Zoological Society p. In: Zoo and Wild Animal Medicine: Current Therapy. Arthropods While Johnson-Delaney (2000) has reported the use of sutures in tarantulas. In: Manual of Exotic Pet Practice. San Diego Lewbart G (2006) Invertebrate Medicine. Goodrum L et al. MA Frye FL (1992) Captive Invertebrates: A Guide to their Biology and Husbandry. 39–43 Ingle RW (1995) The UFAW Handbook on the Care and Management of Decapod Crustaceans in Captivity. Academic Press. Saunders–Elsevier. Harvard University Press. 65–69 Tanada Y and Kaya HK (1993) Insect Pathology. 4th edn. When using cyanoacrylate. Proceedings. the author performed an experi­ mental study with different suture materials in Chilean rose tarantulas (Pizzi and Ezendam. Euthanasia should always aim to be as humane as possible. 2003). BSAVA Publications. British Veterinary Zoological Society Proceedings. Lake Worth. Veterinary Invertebrate Society Newsletter 2 (21). includes a single invertebrate spe­ cies. IA Lewbart G and Christian L (2003) Repair of a fractured shell in an apple snail. pp. Journal of Arachnology 29. American Tarantula Society. 2005) and found the opisthosoma cuticle to have no practical sutureholding ability whatsoever. Saunders–Elsevier. Gloucester Zachariah T and Mitchell MA (2009) Invertebrates. Koninklijke Nederlandse Akademie van Wetenschappen. Potters Bar Cooper JE (1987) A veterinary approach to spiders. Academic Press. Comparative Biochemistry and Physiology C 92. 117– 119 O’Brien M (2008) Invertebrate anaesthesia. St. Saunders– Elsevier. 102 Joosse J and Lever J (1959) Techniques for narcotisation and operation for experiments with Lymnaea stagnalis (Gastropoda Pulmonata). immer­ sion in a fixative (e. Euthanasia Invertebrates are not covered by animal welfare legis­ lation in most countries. which was then hand-fed until the next ecdysis. ed. Carta L and George S (2003) Oral nematode infection of tarantulas. several layers should be applied and allowed to dry to build a sturdy repair. Zoological Education Network. 88–96. Veterinary Record. NY Smith M.g. Sutures simply tore through the cuticle. 695 Pizzi R and Ezendam T (2005) Spiders and sutures: or how to make wounds a whole lot worse.