The common toad, Bufo bufo, can cause poisoning in dogs. Dog owners need to be aware of this danger, especially if you take your dog outside at dawn or dusk in wet summer weather when toads are spawning.

© Ruth Hudson

The common toad, Bufo bufo, can cause moderate to severe toxicity in dogs. Both tadpoles and adult toads can cause poisoning. Signs are generally mild and short-lived. Severe poisoning from toads in the UK is uncommon.

Toads produce a mixture of toxins collectively called bufotoxin, from glands on the head, called parotid glands. Bufotoxin is found in the skin of tadpoles and adult toads. The secretion from the parotid glands is a thick, milky liquid and the toad produces more of it when threatened. Poisoning occurs when a dog licks or mouths toads or picks a toad up in its mouth. Bufotoxin is rapidly absorbed through the oral membranes. Poisoning is most likely in the summer months during spawning. Toads are most active after rain and during dawn and dusk.

Clinical signs of toad poisoning are almost immediate. Common signs include:

• Abundant salivation.
• Pawing at the mouth.
• Shaking the head.
• Distress with whimpering or yelping.
• Retching or vomiting.
• Brick-red color inside the mouth.

• The dog may appear disoriented, blind and unable to walk normally.
• The dog may have difficulty breathing.
• In severe poisoning, the dog may have seizures.

Bufotoxin is irritant to the mouth and has toxic effects on the heart and on the nervous system. Toxic effects include irregular heartbeat, abnormal heart rate (may be abnormally slow or abnormally fast) and elevated blood pressure. Effects on the nervous system are uncommon but may include abnormal eye movements, seizures, and coma. It is unusual for these severe effects to occur following exposure to toads in the UK.

If it is safe to do so, then the dog’s mouth should be immediately flushed with copious amounts of running water. Do not try to flush your dog's mouth if they are having seizures or are unconscious. In the majority of cases reported in the UK there is immediate frothing or foaming at the mouth, sometimes with vomiting, and signs of distress, followed by rapid recovery. If signs do not resolve following flushing the mouth with water, or the dog is having seizures, difficulty breathing or appears disorientated, veterinary attention should be sought without delay. It is not necessary to capture the toad to show it to your veterinarian, because there is only one toxic species in the UK. If there is any risk that the dog has swallowed the toad, swallowed toad tadpoles or eaten any part of the skin of a toad, your veterinarian must be advised of this.

Veterinary treatment may include:

• Monitoring of the heart rate.
• Appropriate cardiac drugs to normalize the heart rate and regularity.
• Fluid therapy to correct imbalances in potassium and sodium in the blood.
• Appropriate medications to control seizures.

Many dogs respond to thorough washing of the mouth. However, the prognosis is more guarded if the dog develops seizures or loses consciousness.

Toad poisoning is not a likely cause of sudden death in dogs in the UK. It is seldom possible to confirm that a sudden death was due to toad poisoning. Occasionally if a dog ate tadpoles or part of a toad, remnants may be found in the stomach, but most dogs that are poisoned have only licked or mouthed a toad.

Owners should be vigilant to ensure that dogs do not lick or mouth toads. It is wise to teach your dog the “Leave!” command.

Cats are rarely poisoned by toads. Toad poisoning may occur in children who handle a toad and then fail to wash their hands before eating food. People with cuts or abrasions on their hands should not handle toads. It is wise to wear disposable gloves if it is necessary to handle toads.