Venomous lizards, alligators and crocodiles, and iguanas can cause clinically significant bites. Tetanus prophylaxis should be given (see table Tetanus Prophylaxis in Routine Wound Management).
Venomous lizards
Venomous lizards include the following:
Gila monster (Heloderma suspectum), present in the southwestern US and Mexico
Beaded lizard (H. horridum) of Mexico
The complex venom of these lizards contains serotonin, arginineVaranus komodoensis], crocodile monitor lizard [Varanus salvadorii]) are also venomous and pose little risk to humans. When venomous lizards bite, they clamp on firmly and chew the venom into the person.
Symptoms and signs of venomous lizard bites include intense pain, swelling, ecchymosis, lymphangitis, and lymphadenopathy. Systemic manifestations, including weakness, sweating, thirst, headache, and tinnitus, may develop in moderate or severe cases. Cardiovascular collapse occurs rarely. The clinical course is similar to that of a minimal to moderate envenomation by a larger species of rattlesnake (see Symptoms and Signs of Snakebites).
Treatment in the field involves removing the lizard’s jaws by using pliers, applying a flame to the lizard’s chin, or immersing the animal entirely underwater. In a hospital, treatment is supportive and similar to that for pit viper envenomation; no antivenom is available. The wound should be probed with a small needle for broken or shed teeth and then cleaned. If the wound is deep, an x-ray can be done to rule out a retained foreign body or bone fracture. Prophylactic antibiotics are usually not recommended.
Iguanas
Bites and claw injuries from iguanas are becoming more frequent as more iguanas are kept as pets. Wounds are superficial, and treatment is local. Soft-tissue infection is uncommon, but when infection occurs, Salmonella is a common cause; infection can be treated with a fluoroquinolone. A secondary but growing concern is infection with Serratia marcescens
Alligators and crocodiles
Alligator and crocodile bites usually result from handling; however, rarely, native encounters occur. Bites are not venomous, are notable for a high frequency of soft-tissue infections by Aeromonas species (usually Aeromonas hydrophila), and are generally treated as major trauma.
