Lizard Venom Poisoning in Dogs

By PetMD Editorial on Jul. 2, 2008

In terms of lizards, the Gila Monster and the Mexican Beaded Lizard are the only ones to be seriously concerned about. These lizards live almost exclusively in the American Southwest and Mexico.

While Gila Monsters and Mexican Beaded Lizards are normally docile and do not often attack, it is important to be aware of the danger if a bite does occur. These lizards have a tendency to bite hard, and not let go. In order to remove it, use a prying instrument to open the lizard's jaws. It has also been found that a flame held under the lizard’s jaw will cause it let go.

These lizards have about forty teeth, which are grooved and not attached to the jaws very firmly, to allow them to be broken off and regrown throughout their lives. There are two glands in the back of the lower jaw, where the venom is stored in a pocket next to the outside teeth and then released through a duct when the lizard bites. The venom is then projected along the grooves of the teeth and into the victim. Salivation increases with the intensity of the anger of the lizard; when that occurs, the amount of venom injected in the victim also increases. Statistically, venom from bites will be deposited into a dog about 70% of the time.

The venom of the two lizards is very similar. However, in contrast to the venom of most snakes, it does not have an anticoagulant effect. Even so, it has been shown to be just as potent as some rattlesnake venoms in lab tests.

Symptoms and Types 

  • Bleeding from the wound
  • Low blood pressure
  • Swelling
  • Excessive salivation
  • Tearing of the eyes
  • Frequent urination and defecation
  • Weakness
  • Irregular heart rhythm
  • Extreme pain at the wound site


Blood analyses, urinalyses, X-rays and ultrasound results will usually come back normal, so a veterinarian does not usually order these. However, they may recommend an EKG to check for abnormal heart rhythms. He will probably also check your dog’s blood pressure. But the only definitive way to diagnose lizard toxicity is by analyzing the venom.


  • Open the jaws of the lizard if it’s still attached
  • If blood pressure is dangerously low or if the heart rhythms are abnormal, intravenous (IV) drugs will be administered to treat the arrhythmia
  • Flush and soak the wound
  • If there are any remnants of the lizard’s teeth, remove them
  • Control pain
  • Treat with antibiotics

Living and Management

The dog must be taken to a veterinarian if you suspect it has been bitten by one of these lizards. The veterinarian will then prescribe treatment and medications. Pay close attention to the wound and report any changes. Most importantly, if you live in an area where these lizards are likely to roam, place your dog behind a fence capable of keeping the lizards out.

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