Lizards

Chapter 7 Lizards

A wide variety of lizards are available in the pet trade. The commonest species encountered are described in Table 7.1. The internal anatomy of a lizard is shown in Figure 7.1.

Table 7.1 Species of lizard most likely to be encountered: Key facts

Species Notes Common disorders
Bearded dragons (Pogona vitticeps) Medium-sized, characterful lizards. They do like it warm, however, and the hot spot should be up to 38°C during the day Metabolic bone disease, Isospora and foreign body ingestion. Secondary infections often are the result of inadequate temperatures
Leopard gecko (Eublepharis macularius) An ideal beginner’s lizard. Feeds well on supplemented insect prey including mealworms. Available in a wide variety of colour morphs, some of which carry very high prices Cryptosporidiosis and foreign body ingestion
Crested gecko (Rhacodactylus ciliatus) Popular because of its looks and wide natural colour variations, this gecko’s wild diet is rich in fruits and so it can be kept using commercially available foods rather than live foods Metabolic bone disease is occasionally seen, as is a muscular-dystrophy-like disease often mistaken for MBD
Green iguana (Iguana iguana) A large stunning lizard as an adult, its vegetarian diet makes it prone to calcium deficiencies Metabolic bone disease, abscessation (secondary to prolonged low environmental temperatures and aggression-related behavioral problems
Veiled chameleon (Chamelo calyptatus) Chameleons are generally not good starter lizards, but the veiled chameleon, providing it is offered water via a spray and given supplemented foods will often do well Metabolic bone disease and dystocia
image

Fig. 7.1 Internal anatomy of a lizard (lateral).

The long-term welfare of lizards is, more so than the majority of snakes, dependant upon correct environmental conditions.

Temperature

Many lizards are ‘exercised’ outside of their vivarium by well-meaning owners. This can lead to prolonged periods of the lizard being exposed to suboptimal temperatures, producing an immunosuppression and increased susceptibility to disease. Inside the vivarium, aggression between its inhabitants can mean some individuals are deprived of suitable basking opportunities, leading to immunosuppression. Some lizards require exceptionally high daytime temperatures. Bearded dragons, for example, need a basking spot set at around 38°C during the day; however, a nighttime temperature drop is no problem.

Ultraviolet exposure

Most diurnal lizards require exposure to ultraviolet B lighting (290–315 nm) for endogenous vitamin D3 synthesis. Dietary supplementation alone is not sufficient for many species including iguanas, bearded dragons, monitor lizards (Varanus spp) and chameleons, so ultraviolet exposure is achieved by installing a full-spectrum light with a specified UVB output, e.g. 2%, 5% or 8%.

Common mistakes include:

1 Failure to provide full-spectrum lighting at all
2 Relying upon placing the reptile close to a sunny window (glass filters out UV light)
3 Use of an incorrect bulb (because glass filters UV light, the bulbs are made from quartz)
4 Failure to replace full-spectrum lights (UV output declines over time but we cannot see this, so replace every 6–8 months or according to manufacturer’s instructions)
5 Allowing intra- and interspecific aggression preventing one or more lizards from gaining a suitable spot to bask beneath the full-spectrum light.

Nutritional supplementation

Crickets, locusts, waxworms and mealworms are commonly fed to lizards not because they are nutritionally good, but because they are easy to farm commercially and they trigger normal feeding in insectivorous species. Insects are inherently low in calcium and so this must be balanced with commercial calcium supplements. These are applied to the insects either by dusting a calcium-rich powder on to the prey, or feeding it upon a calcium-rich food. Note that many commercial calcium supplements also contain vitamins, including vitamin D3, as well as amino acids.

Consultation and handling

Small lizards such as leopard geckos can be examined relatively easily. Larger lizards may require a more managed technique involving assistance – iguanas and monitor lizards rarely bite, however (note this does not mean that they do not bite), and in preference, will attempt to fend you off by whipping with their tail.

Restraint involves grasping the animal from behind across the shoulders and across the pelvis, the handler holding the reptile away from the body. If a large lizard, such as an iguana, is especially aggressive, then placing a damp towel over its head is often sufficient to disorientate it and allow you to gain a hold (N. Highfield pers. comm.).

Many lizards, such as Chinese water dragons and young iguanas, can be temporarily immobilized by applying digital pressure to both eyes simultaneously. This technique, plus gentle handling, will allow many feisty lizards to be weighed and examined in a controlled fashion, before gentle stimulation (such as re-righting the reptile) returns it to a normal state of awareness. This may be a manifestation of the oculo-cardiac reflex.

In those lizards with hypocalcaemia/metabolic bone disease, the bones may be so fragile that fractures of the long bones, especially the femurs, can occur if excessive force is applied. A lizard that is presented as flaccid with little or no muscle tone is likely to be hypocalcaemic. Other causes can include septicaemia or poisoning but these are much less likely. In such cases, i.v. calcium is strongly recommended as soon as possible.

When beginning an examination, examine the head first. Most lizards can be induced to open their mouths even if it is in an attempt to bite you. With iguanas, firm traction on the dewlap will often induce them to open up.

Some lizards will shed their tails naturally if stressed or poorly handled (autotomy). These include iguanids, lacertids, geckos and some skinks. In these species, the tail will regrow but is usually a different shape and or markings. Note that the crested gecko (Rhacodactylus ciliatus) is an exception – unlike the other geckos in the Rhacodactylus genus, the tails do not regrow once shed.

Microchipping

• Left quadriceps muscle, or subcutaneously in this area (all species)
• In very small species, subcutaneously on the left side of the body
• Skin closure is achieved either by suture or with tissue glue.

Sexing

Many lizards are sexually dimorphic as adults and can be readily distinguished, typically by the presence of pronounced pores cranial to the cloaca (pre-analpores) or medial thigh (femoral pores), combined with the presence of hemipenile bulges caudal to the cloaca (Fig. 7.2). Male veiled chameleons have a caudal spur on each hind foot, present from birth.

image

Fig. 7.2 Sexing lizards.

Nursing care

Provide appropriate environment including provision of:

1 Optimal temperature (basking lights, heat mats, etc., to allow thermoregulation). Use of max-min thermometers will assist in monitoring temperature ranges incumbent reptiles are exposed to
2 Full-spectrum lighting (provision of UV-A and UV-B)
3 Humidity
4 Ventilation
5 Easily cleaned accommodation; use paper substrate and disposable/sterilizable hides and other vivarium furniture (Fig. 7.3)
6 Keep individually to minimize intra-specific stress and competition for resources.
image

Fig. 7.3 A clinical vivarium setup for lizards and Chelonia.

Fluid therapy

Reptiles lack the Loop of Henlé and are, therefore, unable to produce hyperosmotic urine. Uric acid is excreted instead of ammonia; this is sparingly soluble and can be excreted at high concentration with minimal water loss as a sludge or paste.

The assessment of dehydration in reptiles can be difficult visually. Typically, signs of dehydration are sunken eyes, extensive skin folding and tenting.

Selection of fluids for reptiles

1 Isotonic fluids for blood loss, surgery and diarrhoea
2 Hypotonic in cases of prolonged anorexia
3 Hypertonic: there is little indication except in exceptionally large reptiles
4 Blood transfusions can be undertaken using blood from a lizard of the same species or closely related (same genus). Blood can be given i.o. or i.v.
5 Oxyglobin
6 Over hydration reptiles with compromised renal function can lead to vascular overload, heart failure and death.

Fluid replacement

1 Plasma volume in reptiles is around 6.0 mL/100 g.
2 Fluid replacement rates are suggested as:
a 0.5–1.0 mL/100 g/h, averaging around 1.5–3.0 mL/100 g/day
b Administer up to 0.5–2% body weight maximum of an isotonic replacement fluid, such as Hartman’s solution, i.e. 5–20 mL/kg, reducing this once the hydration status becomes normal.
3 Daily bathing in shallow, warm water is often beneficial; it encourages many lizards to drink as well as defaecate and urinate.

Fluids administration

1 Stomach tubing is relatively straightforward in smaller lizards.
2 Oesophagostomy tubes can be used in some cases.
3 All parenteral fluids should be warmed to around 26°C.
4 Easiest vein to access is the ventral tail vein. If attempting to use this vein in male lizards, always allow a gap caudal to the cloaca for the hemipenes.
5 Alternatively a surgical cut-down onto the cephalic vein will allow catheterization.
6 For i.o. fluids the tibial cavity (via the tibial crest) is suggested.
7 Intra-coelomic should be used with caution:
a There is a large ventral midline abdominal vein that is likely to be pierced if one attempts to give fluids via the linea alba. There place the needle into a paramedian position – this should also avoid the dorsally positioned lungs
b There is no separation of the coelom into an abdomen and thorax, so excessive fluid build-up can compress the lungs.

Nutritional support

Liquidized normal diet or proprietary support diets can be used, given either by stomach tube or by oesophagostomy tube.

Table 7.2 Lizards: Analgesic doses

Analgesic Dose
Buprenorphine 0.005–0.02 mg/kg i.m. every 24–48 h
Butorphanol 0.4–2.0 mg/kg s.c., i.m. b.i.d.
Carprofen 1.0–4.0 mg/kg s.c., p.o. every 24–72 h
Ketoprofen 2.0–4.0 mg/kg s.c., i.m. every 24–48 h
Meloxicam 0.1–0.5 mg/kg s.c. p.o. every 24–48 h
Morphine 0.05–5 mg/kg i.c. every 6–8 h
Pethidine 2–4 mg/kg i.c. every 6–8 h

Analgesia

Anaesthesia

All reptiles should be at their optimum temperature. Gaseous anaesthetics can be of limited use, as induction agents due to intracardiac shunting, tolerance of hypoxia and physiological diving reflexes (depending upon the species). Chameleons respond relatively quickly while semi-aquatic species may take some time.

Standard anaesthetic protocol

1 Pre-medication
a Atropine sulphate at 0.01–0.04 mg/kg i.m. or i.c. given 10–15 min prior to induction may help prevent intracardiac shunting.

Several anaesthetic protocols have been documented. The author has found the following the most useful:

2 Induction
a Propofol at 10 mg/kg i.v. delivered into ventral coccygeal (tail) vein (for alternative dose rates see Chelonia and Snakes).
3 Intubate and maintain with isoflurane.
4 Most reptiles cease to breathe during anaesthesia, therefore adopt intermittent positive pressure ventilation (IPPV) every 30 s, because high pO2 inhibits ventilation.
5 In larger lizards such as iguanas and water dragons a jugular pulse can be seen sometimes; otherwise the use of pulse oximeters, ultrasound and/or ECG is required for monitoring.
6 For optimum anaesthesia it can be of benefit to infiltrate the surgical site with local anaesthetic.

Parenteral anaesthesia

1 Ketamine at 5.0 mg/kg i.m. plus medetomidine 100–150 μg/kg i.m.
2 Reverse with atipamezole at 5 times medetomidine dose (can take 25–90 min to take effect).

Recovery

1 Continue with IPPV until spontaneous respiration is resumed.
2 If using oxygen alone, switch to manual ventilation with air if possible.
3 Lizards are tolerant of anoxia, therefore continue with IPPV even if there is no obvious response.
4 Doxapram at 5–10 mg/kg i.v, i.o. or on to lingual mucosa may be beneficial.

Skin disorders

The epidermis of both lizards and snakes consists of two layers:

1 The stratum corneum, which consists of:
a Oberhautchen layer
b β-keratin layer
c α-keratin layer
d It is thickened plates of stratum corneum that form the scales. This layer also contains a complex mixture of neutral and polar lipids designed to reduce water loss across the skin
2 Stratum germinativum.

The dermis which is mainly connective tissue – may contain bony plates termed osteoderms.

Most lizards shed their skin piecemeal and uncoordinated – cellular proliferation and keratinization are continuous, however geckos normally shed their skin simultaneously over the whole of the body surface. Many lizards such as leopard geckos (Eublepharis macularis) will eat their shed skin.

Differential diagnoses of skin disorders

Shedding difficulties (dysecdysis)

• Humidity too low
• Other environmental problems – incorrect photoperiod, temperature, nutrition, etc.
• Lack of cage furniture to allow initiation of shedding
• Ectoparasites, e.g. Hirstiella spp, snake mites (Ophionyssus natracis)
• Scarring or other underlying dermal disease
• Hypovitaminosis A
• Hypothyroidism and possibly other endocrinopathies
• Secondary bacterial and fungal infections common.

Pruritus

• Ectoparasites.

Scaling and crusting

• Dysecdysis (see above)
• Bacterial dermatitis (Aeromonas spp, Pseudomonas spp, Serratia spp)
• Dermatophilosis
• Burns
• Hypovitaminosis A.

Erosions and ulceration

• Behavioural interactions with transparent barriers (ITB). Rostral nares and intermandibular joint often affected
• Lesions from hungry, uneaten crickets and other invertebrate prey
• Bites from conspecifics, especially during mating – these are typically over the shoulders and back of the neck.

Nodules and non-healing wounds

• Abscess
• Filarial nematodes (see also Systemic Disorders), esp. chameleons and day geckos.
• Granulomas (mycobacterial – see also Systemic Disorders, fungal, e.g. Chrysosporium anamorph of Nannizziopsis vriesii (CANV), Trichophyton spp, Aspergillus spp, Geotrichium candidum, Cryptococcus neoformans, Aspergillus spp)
• Poxvirus
• Viral papillomas (green lizard Lacerta viridis and occasionally other lacertids). Often very dark to black, and proliferative
• Trichomonas spp (subcutaneous abscesses in leopard gecko)
• Sebaceous cysts (green iguana)
• Pseudoaneurysm, especially on the head (bearded dragon)
• Calcinosis cutis and calcinosis circumscripta
• Endolymphatic glands in certain geckos, e.g. day geckos (Phelsuma spp).

Changes in pigmentation

• Scarring
• Yellowing of skin patches in bearded dragons (Pogona spp). Common following skin disease, e.g. burns, dysecdysis, infections but also linked to ‘yellow fungus disease’
• Yellow fungus disease of bearded dragons. Dermatomycosis: Trichophyton, Chrysosporium anamorph of Nannizziopsis vriesii (CANV).

Ectoparasites

• Arthropods
• Ticks (Aponomma exornatum, A. varanensis, A. fuscolineatum, see Kenny et al 2004)
• Lizard mites (Hirstiella trombidiiformis, Geckobiella spp, Pterygosoma spp)
• Snake mite (Ophionyssus natracis) (Walter & Shaw 2002).

Burns

Neoplasia

• Fibrosarcoma
• Squamous cell carcinoma
• Liposarcoma
• Chromatophoroma (malignant).

Findings on clinical examination

• Distinct single or multiple swellings palpable in the skin
• Dysecdysis: patches of dull, thickened skin may indicate areas where several layers of skin have built up over successive dysecdysis episodes. Rings of unshed skin may form bands around the tips of extremities such as toes and tail tips. These may constrict as they dry, acting as tourniquets and compromising blood flow to the extremities. Lizards that have had previous problems may lack one or more digits
• Thickened skin, hyperkeratotic skin. History of high protein diet, e.g. rodents with no vegetable or vitamin supplementation fed long term to known omnivorous lizards, e.g. some monitors, tegus (hypovitaminosis A)
• Damage to rostral nares and intermandibular joint, linked to repetitive trauma against transparent barriers such as glass doors and sides. Particularly common in water dragons (Physignathus spp), which consistently attempt to leap through the barrier (ITB)
• Anaemia (heavy ectoparasitic infestations)
• Pseudoaneurysm – large fluctuant swelling on neck
• Burns
• Bilateral swellings on the neck of certain gecko species such as day geckos (Phelsuma spp). These are normal calcium storage sites and can be quite pronounced in healthy breeding females.

Investigations

1 Radiography
2 Routine haematology and biochemistry
3 Thyroid levels (Table 7.3)
4 Culture and sensitivity
5 Cytology
a Fine needle aspirate
b Aspiration – whole blood (pseudoaneurysm)
6 Endoscopy
7 Biopsy/necropsy
a Circulating microfilaria (Orós et al 2002)
8 Ultrasonography.

Table 7.3 Lizards: Thyroid levels

Species Total T4 nM/L Total T3 nM/L (Free T3 pM/L)
Sceloporus undulatus Adult 11.1–13.1 3.1–3.2
Ameiva undulata Adult 8.2 –
Dipsosaurus dorsalis Adult 3.2–14.5 –
Dipsosaurus dorsalis Hibernating adult 1.3 –
Dipsosaurus dorsalis Adult (spring) 13.0 0.5
Trachydosaurus rugosus Adult 3.0 0.3
Podarcis sicula Adult – 0.15 (1.7)

After Hulbert (2000).

Treatment/specific therapy

• Dysecdysis
• Moisten the affected areas in order to loosen the retained skin from the underlying epidermis
• Retained spectacular scales in geckos are best removed using a damp cotton bud
• Injection of vitamin A at 1000–5000 IU/kg i.m. will often trigger a further shed, allowing a closer management of the sloughing procedure such that both the old shed and the new are removed
• Supplementation with thyroxine will often help with lizards showing dysecdysis. Serum thyroid levels may be useful, but normal ranges for comparison may not be available for your target species
• Abscess
• Requires surgical removal if possible
• ITB
• Treat lesions topically or systemically as required. May require removal of devitalized bone with associated teeth
• Alter environment – attempt to remove to a larger, more naturalistic environment without transparent boundaries (Scott & Warwick 2002).
• Poxvirus. No treatment
• Viral papillomas
• Usually self-limiting. May require surgical resection if present at a sensitive site, e.g. mouth where they may interfere with normal feeding
• Fungal dermatitis, granulomas, ‘yellow fungus disease’
• Ketoconazole at 10–30 mg/kg p.o. s.i.d.
• Topical ketoconazole cream
• Itraconazole 5 mg/kg p.o. e.o.d.
• Topical chlorhexidine solution
• Topical iodine solution

Note that CANV can act as a primary reptile pathogen

• Filarial nematodes
• Surgical resection where feasible
• Ivermectin at 200 μg/kg s.c. (care with Solomon Island skinks, Corucia zebrata)
• Ticks
• Individual removal of ticks
• Ivermectin at 200 μg/kg s.c. (care with Solomon Island skinks, Corucia zebrata)
Note that ticks are vectors for Babesia/Hepatozoon and Ehrlichia-like organisms
• Snake and lizard mites
• Snake mites are parthenogenetic, so numbers can rapidly build up in vivaria; treatment must include the thorough cleansing of all affected vivaria. What cannot be sterilized with a mild bleach solution (5 mL/gallon) must be disposed
• Replace usual substrate with paper (changed daily)
• Repeated washing with warm water will physically remove any mites
• Application of topical fipronil spray once weekly for at least 4 weeks. This is best first applied to a cloth and rubbed over the entire surface of the snake. Fipronil can also be used to treat the environment
• Injection of ivermectin at 200 μg/kg s.c. (Note: toxic to indigo snakes and chelonia) every 2 weeks will kill those that feed on the lizard
• Commercial imidacloprid (100 g/L) plus moxidectin (25 g/L) (Advocate Dog, Bayer) applied at double (32 mg/kg imidacloprid + 8.0 mg/kg moxidectin) to 10-fold dosages (160 mg/kg imidacloprid + 40 mg/kg moxidectin) according to thickness of skin (care with lacertids especially the six-lined grass lizard Takydromus sexlineatus) (Mehlhorn et al 2005a)
• Cultures of predatory mites (Hypoaspis miles) are commercially available for use in vivaria
• Pseudoaneurysm
• Surgical repair
• Hypothyroidism
• Supplement with levothyroxine at 0.02 mg/kg p.o. e.o.d.
• Calcinosis circumscripta and calcinosis cutis
• Consider surgical resection if viable
• May be linked with renal disease
• Neoplasia
• Surgical resection
• Chemotherapy in reptiles is in its infancy. Accessible cutaneous tumours can be treated by injecting cisplatin directly into the tissue mass on a weekly basis as a debulking exercise
• Radiation has been used to treat an acute lymphoblastic leukaemia in a sungazer lizard (Cordylus giganteus), while surgical laser has been used in the treatment of a dermal melanoma in a green iguana
• Chromatophoromas carry a poor prognosis with early metastasis.

Respiratory tract disorders

Viral

• Ophidian paramyxovirus (OPMV).

Bacterial

• Mycobacterial (see also Systemic Disorders)
• Bacterial pneumonia (especially water dragons).

Fungal

• Mycotic pneumonia
• Mycotic pleuritis.

Parasitic

• Lungworms (Entomelas spp) (verminous pneumonia)
• Pentastomids, e.g. Raillietiella, esp. monitors (Varanus spp).

Neoplasia

• Metastases.

Other non-infectious problems

• Sneezing in iguanas – normal removal of salts from nasal salt glands
• Firefly (Photonis spp) intoxication (see also Systemic Disorders and Cardiovascular and Haematological Disorders)
• Aspiration pneumonia (following oral administration of food or fluids; regurgitation after stomach tubing)
• Glottal foreign bodies
• Cardiovascular disease (see Cardiovascular and Haematological Disorders)
• Epistaxis (metastatic mineralization of nasal vasculature, trauma, infection, liver disease)
• Anaemia (various causes).

Findings on clinical examination

• Dyspnoea
• Tachypnoea
• Open-mouthed breathing and respiratory distress
• Oral and/or nasal discharge
• Unusual respiratory noises
• Altered colour of respiratory membranes (cyanosis, pallor)
• Neck extension
• Epistaxis
• Anorexia
• Depression
• Muscle wastage
• Sudden death.

Investigations

1 Microscopy
a Sputum examination (either from mouth, pulmonary lavage or endoscopic collection)
b Staining for cytology
c Gram stain
d Lungworm eggs and larvae
e Pentastomid eggs
2 Faecal examination
a Pentastomid eggs
b Entomelas eggs (swallowed from trachea)
3 Radiography
a Pneumonia – areas of increased opacity in the lung fields
4 Routine haematology and biochemistry
5 Serology for OPMV
6 Culture and sensitivity
7 Endoscopy
a Adult pentastomes present in lung
8 Biopsy/necropsy
9 Proliferative interstitial pneumonia (OPMV)
10 Ultrasonography.

Management

• If very cyanosed, provide oxygen. Otherwise normal supportive care (see Nursing Care).

Treatment/specific therapy

• OPMV
• No direct treatment
• Supportive treatment only
• Often asymptomatic – frequently diagnosed and monitored serologically
• Lungworm
• Fenbendazole at 50–100 mg/kg. Repeat every 2 weeks if necessary. Note that fenbendazole is metabolized to oxfendazole by the liver
• Oxfendazole at 68 mg/kg. Repeat every 2 weeks if necessary
• Ivermectin at 0.2 mg repeated every 2 weeks for 3 treatments (care with Solomon Island skinks, Corucia zebrata)
• Lungworms have a direct life cycle; infective larvae can penetrate the skin or infect via the contaminated food and water
• Pentastomids
• Ivermectin at 0.2 mg repeated every 2 weeks for 3 treatments (care with Solomon Island skinks, Corucia zebrata)
• Foreign body
• Attempt surgical removal. Likely to need tracheotomy
• Epistaxis
• Investigate possible causes
• Anaemia
• Investigate causes, e.g. haemorrhage, high ectoparasite load, gastrointestinal disease, renal disease, etc.

Gastrointestinal tract disorders

Disorders of the oral cavity

In crested geckos, calcium is stored in bilaterally symmetrical endolymphatic glands dorsally at the back of the pharynx. In breeding females on a good calcium intake these can appear as quite pronounced whitish to greyish swellings and should not be mistaken for pathological lesions.

• Periodontal disease
• Especially affects acrodont lizards (agamids – including bearded dragons, water dragons and chameleons)
• May be related to feeding soft insects, e.g. crickets, waxworms
• Discolouration, loss of tissue and teeth, osteomyelitis
• Radiography to assess underlying osteomyelitis
• Culture of lesions
• Appropriate antibiosis
• Ultrasonic and instrument scaling
• Regular cleaning with oral cleansing product as control measure
• Metabolic bone disease
• Softening or pathological fractures of the mandibles
• The weakened bone is unable to support orthopaedic techniques; in some cases supporting the jaw closed with strong adhesive plaster (taking care to leave the nares open) accompanied by placement of an oesophagostomy tube may allow healing to occur
• Ossifying fibroma
• Usually unilateral; typically affects mandibles
• Occasionally seen in iguanas
• Surgical debulking and/or cryosurgery
• Usually self-limiting
• Other neoplasia (Fig. 7.4)
• Fungal mandibular periodontal osteomyelitis
• Attempt systemic antimycotics such as:
• Ketoconazole at 10–30 mg/kg p.o. s.i.d.
• Topical ketoconazole cream
• Itraconazole 5 mg/kg p.o. e.o.d.
• Stomatitis
• Uncommon. Often linked with respiratory or gastrointestinal diseases (see Gastrointestinal Disorders). See Snakes for further advice on treatment of stomatitis
• Mycotic (Emmonsia spp)
• Herpesvirus (Wellehan et al 2003c)
• Infection of the temporal glands on chameleons
• Swellings dorso-lateral to the angle of the jaw. Requires debridement under general anaesthetic and appropriate antibiosis
• Pharyngeal oedema
• Renal disease
• Cardiovascular disease
• Icterus (see Hepatic Disorders; Cardiovascular and Haematological Disorders). Adult bearded dragons naturally have very yellow mucous membranes
• Cyanosis (see Respiratory Tract Disorders)
• Disorders of the tongue
• In many lizards including the green iguana the rostral tip of the tongue bears a symmetrical darker patch that may be mistaken for an ulcer or inflammatory condition
• Chameleons and monitor lizards have long tongues that are vital for food location and prehension
• Lingual sheath may become infected and adhesions may result. Debride under general anaesthetic and instigate appropriate antibiosis
• Hypocalcaemia/metabolic bone disease in chameleons may present as partial or complete paralysis of the tongue
• In some old chameleons there is a failure of the tongue protruding mechanism. These must be hand-fed.
image

Fig. 7.4 Oral mass in a pink-tongued skink.

Differential diagnoses for gastrointestinal disorders

Viral

• Reovirus (Drury et al 2002)
• Adenovirus (fat-tailed gecko Hemitheconyx caudicinctus) (Wellehan et al 2003b)

Bacterial

• Salmonella spp
• E. coli
• Other bacteria.

Fungal

• Mycotic enteritis (esp. chameleons)
• Yeast infections (in some cases may be linked with long-term antibiosis).

Protozoal

• Cryptosporidium spp
• Flagellates, e.g. Trichomonas, Trichomonas
• Giardia
• Isospora (esp. I. amphiboluri in bearded dragons)
• Eimeria spp
• Cilates, e.g. Nyctotherus (green iguana), Clevelandellida spp

Parasitic

• Hookworms: Oswalsocruzia spp
• Spirurids (stomach worms), e.g. Abbreviata spp, Physaloptera spp (in ant-eating lizards, e.g. horned lizard (Phrynosoma)

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Aug 21, 2016 | Posted by in EXOTIC, WILD, ZOO | Comments Off on Lizards

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