Toads are slow-moving amphibians that move in erratic ways, making them an irresistible target for many predators, including your dog, which may want to eat the toad or merely play with it. However, toads are toxic, as they are able to secrete a poison through their skin. That means that if your pup eats, licks, or chews on a toad, it is potentially at risk for toad poisoning.
Most such dog-vs-amphibian encounters only cause temporary mild symptoms, including drooling or vomiting. However, toad poisoning from certain species, including the giant toad and Colorado River toad, can lead to severe reactions, including seizures, difficulty breathing, abnormal heart rhythms, and even death without prompt treatment.
Your dog is at the highest risk of toad poisoning from March through September, which is breeding season for toads. Toad encounters are most common after it rains, at night, at dawn, or at dusk, as those are the times when the amphibians are most active.
What Is Toad Poisoning?
Because quite a few other animals prey on toads, including snakes, birds, and raccoons, the amphibians have developed a defensive mechanism to protect themselves: They can secret a toxin that can kill a small animal, sicken larger animals, and even cause allergic responses in humans who touch or ingest them.
Toad toxin is secreted from large glands around the amphibians' eyes and from smaller glands distributed throughout the skin. Should a toad become alarmed or defensive, tiny muscles in its skin contract rapidly, forcing the thick, white toxin out of the glands and onto the surface of the animal's skin.
The toad toxin contains a variety of potentially harmful components, including bufagenins, which can affect heart rate, and bufotoxins, which affect nerve conduction in a manner similar to anesthetics.
Toads are poisonous in all stages of their lifecycle, including eggs and tadpoles. Their toxin can even permeate the water around them. However, most North American toads are too small to be lethal to animals much larger than themselves.
Symptoms of Toad Poisoning in Dogs
Once a dog licks, eats, or bites a toad, the strength of the ensuing symptoms depends greatly on the species of toad, the size and general health of your dog, and the length of the encounter. However, because toad toxin is very irritating, your dog will almost immediately show signs of discomfort, including frothing at the mouth, shaking the head, and pawing at the mouth. Your dog might vomit, whine, or whimper.
Depending on the severity of the poisoning, you may see some or all of the following symptoms.
Thankfully, most cases of toad poisoning in dogs aren't too severe, and your dog will only experience mild symptoms, although those symptoms can last for several hours. However, with more severe cases, your dog will quickly progress from the initial mild symptoms to experiencing difficulty in walking or moving normally. You might see your dog shaking or having muscle tremors, and if you look closely, you might notice that your pet's eyes are moving abnormally.
As the poisoning progresses further, the toxin can speed or slow the heart rate, as well as cause abnormal heart rhythms and seizures. Eventually, your dog might collapse and appear unconscious. Without treatment, your dog may die.
Causes of Toad Poisoning
Fortunately, the majority of toads in North America aren't very large, and thus, aren't too toxic to most dogs. However, in the United States, there are two main species of toads to worry about. These are the Colorado River toad and the giant toad.
The Colorado River toad, Incillus alvarius, is also known as the Sonoran Desert toad and is found in northern Mexico and the southwestern United States, particularly in California, New Mexico, Arizona and Texas. The Colorado River toad can grow as large as 7.5 inches in length.
The most toxic toad in North America is the giant toad (Rhinella marina), also called the cane toad or marine toad. Although native to South America, the giant toad is now commonly found in Florida, Texas, Hawaii, Louisiana, and other tropical areas. It earned its common name thanks to its enormous size, which can reach 9 inches in length.
While your dog is most likely to suffer severe poisoning from an encounter with a Colorado River toad or a giant toad—their large size means a larger dose of toxin—it's important to remember that all toads, even small ones, are capable of secreting toxins that can harm your dog. If your dog mouths, bites, or eats a toad, it is also ingesting the toad's toxin. Once inside the dog's mouth, the toxin is quickly absorbed through the mucus membranes and into the dog's system.
Diagnosing Toad Poisoning in Dogs
There is no specific test for diagnosing toad poisoning. If you saw or strongly suspect that your dog mouthed a toad, the diagnosis is easy. If not, the veterinarian will base a tentative diagnosis on the dog's symptoms, particularly if you live in an area where giant or Colorado River toads are common.
Your veterinarian might draw blood from your dog to check for hyperkalemia, which is an abnormally high calcium level, as well as serum digoxin levels. Both of these blood values can become elevated when a dog ingests toad toxins in large amounts. Blood panels to check organ function are frequently ordered as well. If your dog is having abnormal heart rhythms, the vet might also run an EKG, which shows details of the heart's rhythm and pulse rate.
As with most cases of poisoning, this is a true emergency. Both of the toad species listed above can be lethal very quickly, even to a large dog. Because small amounts of venom are usually absorbed through mucous membranes, you cannot treat toad poisoning by inducing vomiting. There’s nothing in your dog’s stomach to expel, unlike in the case of chocolate poisoning.
On your way to the hospital, if possible, flush your dog’s mouth and mucous membranes with large amounts of water. Time is of the essence in this case. Your veterinarian will also flush your dog's mouth, eyes, and face with water, taking care not to get fluid into the animal's lungs. If your dog actually swallowed the toad, the vet might need to perform surgery or an endoscopy to remove the amphibian from your dog's stomach.
After rinsing away as much toxin as possible, treatment becomes mostly supportive. However, dogs that are having severe symptoms may need drugs to control the heart rate, stop seizures, and relax the muscles. Intravenous fluids are usually given, as well. For dogs that are especially ill, the vet might administer Digibind, a medication that helps normalize heart function. An intravenous fat solution is another option for very ill dogs.
Prognosis for Dogs With Toad Poisoning
Fortunately, most dogs with toad poisoning will only become mildly ill and will fully recover with quick treatment to rinse the toxin away as much as possible. For dogs that ingest a large amount of toxin, however, particularly dogs that tangled with a Colorado River or giant toad, the prognosis is more guarded. Still, with immediate care, your dog is likely to survive.
How to Prevent Toad Poisoning
Dogs are most at risk for toad poisoning if they spend a lot of time outdoors unsupervised. They are most likely to come in contact with toads during the warmer, wetter months, especially around dawn or dusk, so be particularly vigilant during these times.
It's especially important to teach your dog a solid “leave it” cue if you live in an area inhabited by Colorado River or giant toads, but it's a good idea to teach the cue to all dogs, particularly puppies or dogs with high prey drive. If you know that your dog is likely to ignore your leave-it cue and attempt to chase or eat something, then your dog should not be allowed to roam freely outdoors.
You can also reduce the likelihood of toads coming towards your house by keeping your grass short and keeping water sources away from your dog’s favorite corner of the yard.
Toad Poisoning in Dogs. VCA Animal Hospitals.
Toads. The National Wildlife Federation.
Toad Poisoning in Dogs and Cats. Merck Veterinary Manual.