Elliott DL Dip Vet Nur BVSc, Bird and Exotic Animal Hospital, Onderstepoort Veterinary Academic Hospital
The most obvious characteristic distinguishing the reptiles from other classes of animals is the presence of a scaled skin. Scales consist of modified epidermis and are formed from specialised keratin. Scutes, present in crocodilians and turtles also have underlying bony plates, the osteoderms. These structures act as a natural armour for the bearers.
As the keratinised scales cannot grow, the reptile must regularly shed its skin. In snakes the skin is shed periodically in its entirety, while lizards and crocodiles will shed fairly continuously in small patches. Some species of gecko will immediately ingest the shed skin.
Snakes and certain geckos have eyelids that have fused into a clear shield over the eye. These animals should always be examined after shedding to ensure that the eye cap or “brill” has come away from both eyes.
The scaled reptilian skin is much less permeable than that of mammals. Reptiles thus have very low levels of insensible water loss. Their daily fluid requirement, depending on the species is approximately 10 to 20ml/ kg.
When suturing wounds on reptiles, there are several points of which to take note:
- The skin is the layer with the greatest holding ability – the muscles are fragile
- The scaled skin has a tendency to curl inward, meaning that if simple interrupted sutures are used, one will be left with a scale on scale contact which will obviously not heal. We thus use a horizontal mattress (everting) suture pattern in order to allow for tissue contact. This suture pattern causes the skin to lift in a ridge but this will normalise with time.
Figure 1: Leopard Gecko shedding its skin
Figure 2: Removing a retained eye cap
Common dermatological conditions of reptiles:
Mites: Ophionyssus natricis, the snake mite, has a lifecycle that can be completed in as little as 7 days but the mites may remain alive in the environment for a considerable period of time. Besides causing skin irritation and inflammation, severe infestations can lead to anaemia, dehydration and even death. The mite is implicated in the transmission of several viral and protozoal diseases. Mites may easily be visualised clustered around the eyes and under the scales, especially around the head. Affected snakes will often seek refuge in water and drowned mites can be found in the water bowl. Treatment must be focused both on the reptile and the environment. Protocols using Pyrethroids, Dichlorvos strips, Ivermectin and Fipronil have all been effective.
Figure 3: The snake mite, Ophionyssus natricis.
Autotomy: Many species of lizards including geckos, skinks and iguanids have specific fracture planes in their tails allowing the animal to drop the tail when threatened by a perceived predator. The wiggling tail attracts the predator’s attention, allowing the stump tailed survivor to escape.
Figure 4: The ridged suture line is visible in this Bearded Dragon post foreign body removal (chunk of carrot)
For this reason lizards should never be handled by the tail. Reptiles that perform autotomy will typically be able to re-grow the tail (Crested Geckos are an exception), it may however be discoloured or deformed. Should autolysis occur, no sutures should be placed in the stump as this will prevent tail re-growth. The lesion should simply be kept clean.
Figure 5: Autotomy in a Green Iguana – note the exposed muscles. Simply trim these off and disinfect the area
Dysecdysis and shedding storms: Dysecdysis is the term for a failure to shed the skin normally. A healthy snake will go “into the blue” where the skin and eyes become a dull grey/blue colour approximately one week prior to shedding the skin. Reptiles resent being handled while in the blue. In dysecdysis the skin is retained completely or in patches and if removed the underlying scales can be rough or wrinkled. Common causes of dysecdysis include internal parasites, infectious conditions and inadequate environmental humidity. Shedding storms where the animal goes into the blue almost immediately after shedding can occur due to underlying disease or hormonal imbalances.
Dry gangrene: typically occurs on the delicate extremities. Should the animal have trouble shedding, skin will often remain on the toes and tail tip. This dry skin contracts and may cause avascular necrosis. Secondary bacterial infection occurs and may quickly spread up the limb and become life threatening. Amputation through healthy tissue is the treatmenty of choice and antibacterial cover is recommended.
Figure 6: Removing retained skin on the toes of a Leopard Gecko – this condition is caused by inadequate humidity and predisposes to dry gangrene
Figure 7: Dry gangrene in a juvenile Green Iguana
“Scale Rot” or ulcerative dermatitis: Is a condition found most commonly in snakes. Damp, dirty conditions predispose to bacterial dermatitis. Vesicles, crusts and ulcers form on the ventrum and can become very deep. Similar lesions can appear all over the body in septicaemic states. Treatment consists of antibiotics, topical ointments such as F10, anti-inflammatories and correction of the husbandry.
Burn Wounds: typically occur when the reptile gets too close to a heat source in the cage. Heat sources should be reptile approved and positioned in the cage in such a way that the inhabitant receives sufficient warmth without coming into contact with the light or heating pad. Treatment is routine with antibiotics, dressings and analgesia, depending on the grade of the burn. They take a long time to heal and owners need to be prepared for the costs and time that will need to be invested in the treatment.
Figure 8 Septicaemic vesicle “blister disease” in an albino Burmese Python
Figure 9: Healing 3rd degree thermal burn from a heating pad in a Corn Snake
Rodent bites: occur when live mammalian prey is left unsupervised in the snake’s cage. Snakes will rarely kill a rodent simply in defense and if not hungry will simply withdraw as far as possible from the rat. In the confines of a cage, the rodent may then cause severe trauma to the reptile. These large wounds often become secondarily infected and can take months to heal. Live mammalian prey should never be fed to reptiles, both for humane and safety reasons. The vast majority of reptiles can be habituated to feeding on killed prey with a little effort on the part of the keeper.
Figure 10: Rat bite in an African Rock Python – an endangered species that does poorly in captivity and should only be kept by the very experienced herpetologistIssue
Infectious Stomatitis or “Mouth Rot”: Is a common condition, especially in snakes. It begins with inflammation and exudate build up with petechial haemorrhages and if untreated may progress to abscessation and tooth loss or even osteomyelitis.
Treatment includes debriding, oral chlorhexidine or betadine washes and appropriate antibiotic cover. The pathogenic bacteria are typically gram negative so Enrofloxacin, Florfenicol and Ceftazidime are good empirical choices.
Figure 11: Infectious stomatitis leading to abscessation in a Boa Constrictor
Yellow fungus disease: Chrysosporium anamorph of Nannizziopsis vriesii (CANV) is a fungal disease that mostly affects Bearded Dragons although it has been recorded in Green Iguanas, Veiled Chameleons, Water Dragons and Uromastyx.
The lesions begin with yellow to brown crusts in irregular small patches if these crusts are removed the underlying skin is often ulcerated. After a shed the affected skin is wrinkled and dull. The lesions can become very deep, even penetrating the body wall.
Figure 12: Fungal dermatitis in a Green Iguana
Septicaemia may also result and the condition is eventually fatal without treatment. CANV is contagious. Predisposing causes include those that cause immunosuppression such as crowded or dirty conditions, trauma, poor husbandry etc. Short to medium term resolution of clinical signs has been achieved with oral Voriconazole and topical F10SC therapy. Other azoles as well as Terbinafine have not proven effective. Affected animals should be considered lifelong carriers.
Trauma: Tortoises seem to be the most commonly presented trauma victims. Motor vehicle accidents, dog bites in smaller specimens and purposeful injury by people attempting to kill the animal for food are the most common histories.
Figure 13: Tortoise injured by a person wielding a spade
Even severe shell defects can be repaired but this is a field completely on its own. The most important fact to remember is to never seal a tortoises shell until the wound is clean and granulating well, or internal abscessation may occur.
With a basic understanding of the specific structure and function of the scaled reptilian skin, diagnosis and treatment of reptile dermatological issues can become a rewarding although quite drawn out process. There are several good texts such as Reptile Medicine and Surgery by Doug Mader and the BSAVA Reptile Manual available for more detailed diagnostic and treatment advice.
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