Lizard Physical Examination

Ophthalmologic Examination

The eyes are usually considered as a barometer of general health and environmental conditions; therefore a full ophthalmologic examination should be performed in all cases.

• Vision can and should be evaluated by observing certain behaviours such as a menace response.
• Following a general assessment of the eye and associated structures (eyelids, tear film, globe), a more detailed examination should be performed using a form of focal illumination and a magnification system.
• Examination of the ocular fundus to assess the retina (fundoscopy) can be carried out using a direct or indirect ophthalmoscope.
• Mydriasis can be attempted either through general anaesthesia or intracameral injection of neuromuscular blocking agents such as curare or d-tubocurarine. These agents can also be applied topically; however their effectiveness may be affected by the variable corneal penetration of the drugs.
• Other diagnostic tools, such as tonometry (measurement of the intraocular pressure), stains, cytology, bacteriology, histopathology and electron microscopy, in addition to routine diagnostic tools (haemotology, biochemistry, radiology and ultrasound) can also be used to detect an ocular disease or underlying problem in lizards.

(For more information on the eye, see Lizard Eye page.)

Sexing

Sexual dimorphism in Lacerta bilineata (male: left; female: right) (Wikicommons)

Gender identification in juvenile animals may be challenging; however, most lizard species display sexual dimorphism as adults.

• The most reliable method of determining gender is usually by comparing pore sizes. Indeed, adult male lizards tend to have large femoral and precloacal pores on the ventral aspect of the thighs; on the other hand, adult females have smaller, more discrete pores, similar to those seen in juvenile male lizards.

• Sexing probes (cloacal probing) can also be used in iguanas and monitors but aren't as consistently accurate as they are in snakes.

• Injecting saline solution (hydrostatic eversion) into the base of the tail in order to evert the hemipenis is another technique. However, care must be taken to avoid trauma to the hemipenis and prevent pressure necrosis. This method can be useful for species that are difficult to sex such as monitors, Tegus, large skinks, Beaded Lizards and Gila Monsters.

• Temporary eversion of the hemipenes in anaesthetized males can be done by applying gentle pressure at the base of the tail, just caudal to the cloaca.

• In some species, such as iguanas, the hemipenes in mature males will calcify and appear visible on radiographs.

• Endoscopy can be used to visualize gonads.

• Ultrasonic evaluation of the gonads or hemipenes is also possible.

For information on the reproductive system of lizards, see Lizard Reproductive System page.

Measurement

Carry out normal measurement procedures, such as rostrum to cloaca, cloaca to tail tip and weight.