Lizard Venom Poisoning in Dogs

North America and Central America are home to the two known venomous lizards of the heloderma family. H. horridum is the scientific name for the Mexican Beaded lizard, while H. cinctum and H. suspectum are known as Gila Monsters. Our canine friends, due to their curious nature and their interest in encounters with wildlife, are the animals most likely to experience a bite from a lizard. Documentation of confrontations between lizards and dogs is not frequently found, but it is known that the possibility is there. Due to the fact that more people are turning to the exotics for pets means the likelihood of more creatures such as venomous snakes and lizards becoming more widespread in North America.

Venomous lizards are part of the genus heloderma. The toxicity of a bite from either the Mexican Beaded lizard or the Gila Monster lizard will depend on the duration and severity of the bite, and in turn, how much venom has been released in the process.

The amount of venom that a lizard can deposit when biting depends on the size of the lizard, and the length of time that the lizard is attached to the dog. Studies also state that the agitation of the lizard at the time of the bite can determine the amount of venom released as well. Some animals suffer more severe symptoms from a lizard attack than others, with dogs most often displaying the signs below.

• Vomiting
• Bleeding at the site of the wound (which may contain teeth fragments)
• Swelling and bruising at wound site
• Pain
• Rapid breathing pattern (tachypnea) and other respiratory abnormalities
• Urination and defecation, with large amounts of urine (polyuria)
• Excessive tearing (lacrimation)
• High volume of salivation

Low blood pressure and irregular heart rhythm may be evident also.

• The venomous glands are found in the lower jaw
• The venom is released through grooves in the teeth
• The venom is similar to that of snake
• Protein and enzymes in the poison work towards penetrating tissue at the bite location for optimum spread in addition to tissue damage
• These venomous lizards are normally docile but when agitated have an aggressive bite and most often have to be pried off the victim
• The Gila Monster is found in Utah, Arizona, Nevada, New Mexico and Southern California
• The Mexican Beaded lizard is found in Mexico along the Pacific coast into Guatemala

Studies show that removing the lizard from the wound site is the biggest challenge of the diagnosis and treatment. Removal can be accomplished by prying open the jaws of the lizard with a sturdy object. Holding a flame under the chin has been known to work as well. Others have outright killed the lizard by cutting the jugular vein, causing death. Removal of the lizard is key, because the longer the lizard remains attached, the more intense the reaction to the venom. Though heloderma bites are rarely heard of, severe symptoms that your veterinarian may note in your dog once the lizard has been removed are a rapid fall in blood pressure, respiratory distress such as gasping, hemorrhage of organs, and paralysis.

If the lizard has not yet been removed, your veterinary team will carefully attempt the removal. The lizard cannot simply be pulled off as this may deepen the wound, because the lizard will tighten his grip on your dog. After removal, the veterinarian will use lidocaine or a similar substance to numb the wound, so a proper cleaning can be done and a search for tooth fragments can be thoroughly executed.

Pain relief will be offered as it is known from human experience that the bite of a Gila Monster or Mexican Beaded lizard can cause extensive pain at the site of the wound, and surrounding areas. Your veterinarian will need to monitor your pet to ensure a rapid drop in blood pressure is managed should it occur. Shock could set in, therefore the combination of these two factors will mean intravenous therapy could be needed.

Once your pet has been stabilised and the wound has been well cleaned, your dog may be able to leave the clinic. You will have a prescription for antibiotics to administer for the next week or two as lizards are known to harbor bacteria in their mouth. Be sure to complete the entire dosage in order to have complete efficacy. Your veterinarian will also instruct you to check the wound daily to be sure there is no infection. If you feel the wound is not healing properly, contact your veterinarian to make a follow-up appointment at the clinic. If your pet encountered the lizard in the wild, it is best to avoid that area or be certain to keep your dog on a leash while walking in that locale.