Burns in reptiles and amphibians (Proceedings)

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Burns in reptiles and amphibians (Proceedings)

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Oct 01, 2008

Classification of Burns

Burns are classified by the type of burn and by the severity of the injury or extent of the body surface area affected. There are three basic classifications of burns in mammals. These categories can also be used in reptiles & amphibians. Understanding the nature of the burn will help you assess the need for intervention, i.e. is it something the client can treat at home, or, should it be hospitalized for competent/complete medical care ?

The extent and severity of a burn is related to several factors. Obviously the temperature of the heat source plays a significant role. Touching a stove burner set on "warm" will result in a far less severe burn than touching the same burner set on "high."

Duration of contact also affects the severity of the burn wound. Again, touching a stove burner set on "warm" only briefly may result in a minor burn. Whereas, holding one's hand on the same burner for several minutes may result in much more severe tissue damage. This is perhaps why we see such intense damage in reptiles & amphibians that have fallen asleep on what seems like only a mildly hot heating element like a "hot rock".

Finally, the heat conductance characteristics of the material touched also plays a role in the severity of the burn. For instance, touching a hot piece of metal would cause a more severe burn than touching a piece of wood at the same temperature. Also moisture seems to increase the conductance and therefore intensify the possible thermal trauma.

Types of burns include thermal, electrical, chemical and radiation. Thermal burns include all the categories discussed thus far, i.e. burns by hot rocks and heat lamps. An electrical burn, although not common in reptiles, can be seen where there is direct contact with an electrical current, such as when there is a short in a wire that has electrical arcing, or when an animal bites through an electrical cord that is plugged into a live socket. Chemical burns are caused by strong acids or alkalis, such as cleaning supplies like pure bleach (an alkali agent). These are also uncommon in reptile patients, but may occur, especially when chemicals are spilled or agents are not thoroughly rinsed after cleaning a cage. Radiation burns in reptiles are extremely uncommon. These are usually related to the use of radiation therapy when treating certain types of cancers. Since radiation therapy has been used in reptile patients, this type of burn is possible.

In older terminology, burns used to be classified as first, second or third degree, depending on the severity of the damage. In more recent classification, the terms partial thickness and full thickness burns, are more commonly used. "Thickness" refers to the outer layer of skin.

First degree burns are superficial, or partial thickness injuries that only involve the epidermis (outer skin). These burns are painful. In mammals there may be damage to the hair or fur (singing). The skin is reddened, and in severe first degree burns there may be blisters (such as in a severe sun burn). In reptiles & amphibians, one rarely see blisters, although they may occur, and occasionally, one may see singing of the scales, depending on the type of exposure. Usually, one will see reddening of the skin, and often what looks likes "bruises" under the scales, especially in white, pale or clear scales. In amphibians these can be serious injuries and should be treated appropriately. In reptiles, these burns usually heal well and rarely leave a scar. In an otherwise healthy reptile, healing takes about one month and a good shed for the burn to completely resolve.

Second degree burns are deeper partial thickness injuries with usually full destruction of the epidermis, and variable damage to the underlying dermis (inner, deep layer). In mammals, although there is more damage to the dermis, the fur or hair may not necessarily be damaged. The burns are very painful, and extensive subcutaneous swelling does occur. In amphibians these are even more serious injuries and unless treated immediately and completely, effected animals may not survive. In reptiles, blistering and oozing of serum from the burn site are seen. There is extensive bruising and discoloration of the tissue. These injuries lead to the formation of a scab-like covering over the burn. In both reptiles & amphibians healing occurs from the margins of the wound inward. In these wounds, especially in burns that cover a large surface area, healing may be prolonged and significant scarring may occur.

In third degree burns, the entire thickness of the skin is destroyed. The burn is actually painless (all the pain sensing nerves are destroyed), and the tissue takes on either a whitish or charcoal black appearance. In mammals the hair and fur fall out or are destroyed. Third degree burns are four times as serious as second degree burns of similar size. These wounds are usually fatal for amphinians. Healing of third degree or full thickness burns occurs by contraction of the wound (shrinking) and epithelialization (re-growth and migration of new skin from the margins of the wound toward the center). In some cases of third degree burns, skin grafting may be necessary. These burns may take many months (4 - 6) to heal completely. Severe scarring is a hallmark of third degree burns.

The classification of a fourth degree burn is occasionally used to describe a third degree burn that not only involves the full thickness of the skin, but also the underlying tissue such as muscle and bone. These injuries carry a grave prognosis.