Bufo marinus - A Frog That Can Kill Your Dog

Wednesday, February 08 2006 @ 08:15 pm EST

Contributed by: Don Winner

The practice of “toad-licking” has evolved into an urban legend – that the venom secreted through the skin of some toads cause hallucinations. In fact, the venom has been cultivated for generations to be used for medicinal purposes in human beings. However, the venom is highly toxic to pets. Dogs, which are the most likely pet to come into contact with a toad, have a high probability of dying if untreated. This toad wouldn’t win any awards for beauty; its brown/green skin is usually covered with warts. They grow to be about three to seven inches long, and is very toxic to pets. Because dogs are more curious and extroverted, they tend to be treated for toad poisoning more often. But a dog doesn’t necessarily have to lick or eat a toad to be poisoned. There have been cases where frogs have been attracted to a dog’s water dish and sat along the rim. Enough toxin can be left to make a dog sick.

(Editor's Comment: Bookmark this page. You might need it in a couple of years when Sparky the Wonder Dog eats one of these things, and you're trying to remember what to do...)

What to Look For

If enough toxin is ingested, your pet may have an irregular heartbeat and act strangely, as if in the grip of a hallucination. Call your veterinarian if you observe:

Mouth irritation with foamy salivation
Difficulty breathing

Veterinary Care

An electrocardiogram may be conducted to determine whether your pet has an abnormal heart rhythm. There currently is no way to find the presence of the toxin. Diagnosis is usually based on whether the pet was seen eating a toad, or if toad parts are in the gastrointestinal tract.

If your pet ate or licked a toad, you should flush his mouth with water to remove traces of the toxin. Your veterinarian may give your pet cardiac drugs such as propranolol to combat abnormal heart rhythms. Anxious, frightened or painful pets may need sedatives. Pet's with a high fever may benefit from a cool bath. A hospital stay with intravenous fluids is very likely, with your pet’s heart monitored by an electrocardiograph.


"Bufo marinus was introduced to northern Queensland in 1935 in an attempt to control the population of a type of beetle that was ravaging the sugar cane crops. The toads ignored the cane beetles, but began ravaging everything else in sight instead. They have immense appetites, breed by the zillions, and secrete poisonous gunk that makes them unpalatable to all but a tiny handful of native Australian animals (and dangerous to many). When we went out on wet nights in tropical northeast Queensland, we saw a variety of native frogs, but the cane toads outnumbered them at least 20 to 1. The toad pictured here looks like he's hanging his head in shame at what his species has done to the native wildlife."

Other Names: Cane Toad, Giant Toad, Marine Toad, Spring Chicken (Belize)


Giant Toad - Introduced
Bufo marinus
(click images to enlarge)

Appearance: Giant Toads range in size from 4 - 6 in. (10 - 15.2 cm). Females can weigh up to 3.3 lbs (1.5 kg). Giant Toads are huge brown toads that vary in color between brown and red and may have darker and lighter spots/marblings. Females generally have more patterning that the males. The body tubercles of males are tipped with tiny spines. The distinguishing characteristic of the giant toad is the enlarged parotoid gland. The immense parotoid glands extend far down the sides of the body. These glands secrete highly toxic substances that can poison and even kill dogs and other animals that happen to bite into them.

Habitat: In Florida, Giant Toads can be found associated with urban and agricultural areas. This species breeds in canals, flooded ditches, shallow pools and fish ponds. At night, Giant Toads have been known to congregate around house lights to feed on insects. They will seek shelter beneath ground debris in dry and cold weather. Giant Toads are a highly predacious exotic species that will eat all types of native frogs and toads. This species is skilled at locating all types of food, they have even been known to eat dog food.

Vocalization: The Giant Toad call is a slow, low-pitched trill that has been compared to the sound of exhaust noise from a distant tractor. The largest males tend to have the deepest voices.

Reproduction/Eggs: Breeding depends on the occurrence of rains, but it may occur from early spring to autumn. A single, large female is capable of producing more than 20,000 eggs. The egg strings may float freely but are more often secured to surface or submerged vegetation.

Abundance: The Giant Toad is primarily a native of tropical America. The Florida population probably results from both introductions and pet trade escapes. The Florida Giant Toads are probably of Colombian origin. These toads are abundant in Dade and some areas of Monroe Counties. Giant Toads also occur in lesser numbers in Broward, Glades, Lee, Okeechobee, and Pinellas Counties. For the Florida toads, those in the southern part of the range generally attain a greater size (6 - 7 in.) than those in the northern areas (3 - 4 in.).

Range: Giant Toads range from extreme southern Texas and southern Sonora south to and through the Amazon Basin in South America. Giant Toads are introduced in and around Miami, Florida and Tampa on the Gulf Coast. Giant Toads are also found on Stock Island and Key West.

SE ARMI Index Sites: Everglades National Park, Virgin Islands National Park.


Meet Mr. and Mrs. Giant Toad

The Giant Toad (a.k.a. Marine Toad or Cane Toad) is the largest of the Florida frogs and toads. When this non-native species is threatened, it secretes a highly toxic milky substance from its large parotoid glands in the back of its head. This secretion will burn eyes, may inflame the skin, and can kill cats and dogs if they ingest it.

Originally released in sugar cane fields to help control rats and mice, it now is commonly found in South Florida yards. It breeds year round in standing water, streams, canals and ditches. The call is a low-pitched trill which sounds like an idling diesel engine.

Known scientifically as Bufo marinus, the Cane Toad, Giant Toad, or Marine Toad is native to an area extending from Mexico and Central America to the Amazon Basin.

Florida's first Giant Toad population was established in 1955 by an accidental release at Miami International Airport. Specimens imported by a pet dealer escaped and spread through canals to other areas. Pet dealers deliberately released the toad elsewhere in southeastern Florida in the early 1960s.

Bufo marinus can grow to 9 inches in length and more than 2 pounds in weight. Giant Toads prefer developed areas, where they use man-made canals and ponds for spawning and gather under electric lights to feed on insects. As the Giant Toads are too large and slow to flee predators, they defend themselves by secreting a milky toxin from glands located behind the head. Giant Toads can live for a least 15 years in captivity, and can breed for at least five years in the wild.


Giant Toads are heavily built, have short legs and no webs between their toes. Adults have a rough warty skin. Their color is tan, dull green or black, with a light underside. They have large glands behind the head which exude a poisonous milky substance when the toads are attacked.

The spawn consists of long double chains of black eggs enclosed in a transparent cover. They develop into tadpoles which form large, slow moving shoals.

Food Habits

Giant Toads are omnivorous. They eat whatever is available. They will eat almost anything they can get a hold of -- small amphibians, reptiles, birds, and mammals. In fact, they eat any animal they can swallow, and cat or dog food -- unlike other amphibians, Giant Toads eat things which do not move so do not leave cat or dog food outside for your pets -- the toads will sit in the bowls and eat it.


Giant Toads breed from June to January, but toads have been found in breeding condition throughout the year. Females produce 8,000 to 50,000 eggs in a clutch and can breed at least twice a year. Giant Toads normally lay eggs in slow moving freshwater streams, but they can also breed in brackish water. Tadpoles hatch in 48 to 72 hours. Depending on the water temperature and food availability, they can complete their development in 16 to 180 days.


Giant Toads produce poison from glands behind the head. The poison is highly toxic to most animals and produces pain and local inflammation if it contacts the eyes. Most predators are quickly killed after ingesting this substance.

Dogs and cats which bite Giant Toads die within a few hours. Native species of reptiles and mammals are also vulnerable. The eggs and tadpoles of Giant Toads are also poisonous.


Biological control is probably the only practical means of limiting the spread or reducing the number of giant toads. However a recent study found little or no hope of such a control method. Giant toads are often transported in shipments of fruit and other commodities. Until effective control methods are available, quarantine checks and the destruction of any accidental releases of toads are essential to reduce their rate of spread.

The Choice is Up to You

Giant toads are beneficial for the gardener and homeowner in general. They have a huge appetite and eat millions of insects per year. They are poisonous, but only if carelessly handled -- they do not attack humans or other large animals. They do displace native toads and reptiles and will eat other small mammals and birds if they can catch them.

Giant Toads can be removed and disposed of humanely (as recommended by the IFAS Animal Use Approval Committee) by placing them in a plastic container (or bag) in the freezer for three days and then burying the carcasses. If you do not wish to handle the toads, contact a local nuisance animal trapper. At FloridaGardener.com we believe that there seems to be no real need to make an active effort to control Giant Toads as they are more beneficial than harmful in the home yard and garden. However, if the population of toads grows out of control or you believe they may be a threat to your children, pets, or wildlife in your yard, then you may find it necessary to control the population in your yard.


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