10 Most Dangerous Creatures for Your Pets

1. Rattlesnakes

Rattlesnakes are probably the most important threat in this slideshow to be aware of, as hiking dogs may not recognize a rattler’s scent or sounds – and end up bitten on the muzzle, says Dr. John Tegzes, a veterinary toxicologist at Western University School of Veterinary Medicine. The venom acts on various tissues causing swelling, oozing and clotting of blood, and necrosis of tissues as the venom works to immobilize its prey and to start the digestive process. Bleeding problems often occur in the following days and can be life-threatening.

Location: Many states harbor some variety of rattlesnakes, but the Mojave rattlesnake is regarded as the most dangerous because its neurotoxins stop prey from breathing, says Dr. Tina Wismer, veterinary toxicologist and medical director for the ASPCA Animal Poison Control Center. Mojaves call the Southwest home.

Rattlesnakes dominated the 251 snake-bite claims handled in 2011 by Veterinary Pet Insurance; snake bites, on average, cost $1,123.08.

What to do if your pet is bitten: Limit your pet’s movements, keep him calm and seek immediate veterinary care.

2. Giant Toads

Very dangerous to dogs, a Giant Toad secretes a toxin from its skin that causes heart failure, Dr. Tegzes says. A dog just needs to pick up the toad and hold it in his mouth to be exposed. Also called Cane Toad, Marine Toad or Bufo Toad, the critters can bring agony: excessive drooling, crying, extremely red gums and loss of coordination number among pets’ symptoms.

RELATED: Secret Sex Lives of Animals

Among the 339 outdoor-critter-related calls for help to the ASPCA Animal Poison Control Center in 2011, poisonings by Bufo toads and the Colorado River toad were most common, Dr. Wismer says, beating out ants, wasps, bees, snakes, spiders and others. Toad poisonings prompted 51 VPI insurance claims in 2011, costing an average $304.03 per pet.

Location: Hawaii, Florida, extending across the extreme southern parts of the country.

What to do if you pet is poisoned: At home, Dr. Tegzes says, the victim’s mouth should be well irrigated with a garden hose. “Simply run the water into the side of the dog’s mouth and out the other side,” says Dr. Tegzes. “But do not run the water to the back of the throat. You want to gently rinse its mouth very thoroughly and get veterinary attention.”

3. Brown Recluse Spiders

A brown recluse spider’s bite it not really painful right away, but the bite grows into a very large, deep-tissue wound that doesn’t want to heal, Dr. Wismer warns. Wounds can be very difficult to treat, agrees Dr. Tegzes, and can result in lifelong damage that often requires surgery to correct.

Location: Midwest and South-Central United States (map).

What to do if your pet is bitten: Seek veterinary treatment.

4. Cottonmouth Snakes

This is a snake that swims. The venomous cottonmouth snake, also known as the water moccasin, likes to hang out at water’s edge, making it a threat to dogs and cats near ponds and lakes. It seldom bites — unless stepped on or harassed. Its venom is very similar to a rattlesnake’s, though tends not to be as serious, Dr. Tegzes says.

What to do if your pet is bitten: Keep your pet calm and seek immediate veterinary care.

Range: Mainly the Southeast, from southern Virginia to Florida and onto eastern Texas (map).

RELATED: 7 Animals With the Longest Life Spans

5. Gila Monsters

Gila monsters are rare, but eventful – they latch onto and chew on their victim for a long time, injecting venom from their teeth in the back of their mouth. “It can be very difficult to remove the Gila monster from its victim,” Dr. Tegzes says, “and dogs will often present to the veterinarian with the lizard still attached and biting!” The painful bite can cause neurological signs, but usually is not life-threatening.

Location: Southwest.

What to do if your pet is bitten: Don’t pull off the lizard with force. Often its teeth will detach and remain embedded in the dog. Instead, spray some water or rubbing alcohol onto the Gila monster’s nose, Dr. Tegzes says, and it will let go on its own.

6. Black Widow Spiders

Black widow spiders are somewhat reclusive and non-aggressive, but dogs and cats can be bitten when they walk through a spider web outdoors or accidentally lie down on a spider, Dr. Tegzes notes. Cats are very sensitive to the venom, which is 15 times stronger than a rattlesnake’s. The venom can send extreme pain throughout cats’ bodies and cause muscle rigidity, followed by a loss of muscle tone.

Insect bites and stings, including spiders, prompted 2,428 claims to VPI pet insurance in 2011, costing an average of $141.23 per pet.

Location: More abundant in the South, but black widow spiders are found in most of the Western Hemisphere.

What to do if your pet is bitten: Seek veterinary care. 

7. Fire Ants

A dog keeping his nose close to the ground to explore may suddenly cry out, leap back and start pawing his nose. Chances are that his nose hit a colony of swarming fire ants that deliver burning bites. Fire ant bites aren’t as serious as other threats in our list, but they do send dogs to veterinary clinics for sore paws and injured noses. “I’ve been bitten by fire ants and it’s no fun,” says Dr. Mark Russak, president of the American Animal Hospital Association.

Location: South, from North Carolina through Texas; also, southern California, New Mexico.

What to do if your pet is bitten: Check with your veterinarian for treatment; if nothing else, rinse area with cool water to reduce swelling, Dr. Russak says.

RELATED: 10 Household Plants Dangerous for Pets

8. Eastern Coral Snake

Easily mistaken for harmless look-alikes, the Coral snake can be remembered by this rhyme that refers to its bright color bands: “Red touch yellow kills a fellow. Red touch black, venom lack.”

The Coral snake injects toxins that will stop a pet’s breathing. On the bright side, unlike Mojave rattlesnakes, Coral snakes actually have to chew a little bit to inject venom because their venom glands are back farther in their mouth. Dr. Wismer says: “Fortunately we don’t have too many dogs and cats having problems that way, but certainly if they do get bit, it can be a big problem.”

Location: The South, from North Carolina to eastern Texas.

What to do if your pet is bitten: Seek immediate veterinarian care.

9. Bees

You may hear a yelp from your dog and then within 20 minutes, see his face swell in size. The cause behind the swollen face may be a reaction to a bee sting. “Fatal reactions are rare, but they do occur,” says Dr. Russak. Most dogs tend to have a mild reaction, and often a first-time bee sting causes no trouble. It’s the subsequent stings that can be severe. “Bee stings, if you can avoid them, are critically important to stay away from.”

Location: Bees are in all states.  Africanized honey bees are found in the Southwest, Florida, Arkansas, Oklahoma, Texas.

What to do: Seek prompt veterinary attention. If you absolutely can’t get to a veterinary clinic (say, you’re in the mountains far from any town), give a small dog a child’s dose of antihistamine; give an adult dose to a large dog, he says. Dr. Tegzes views bees as more nuisance than life-threatening, although Africanized bees are very aggressive. “They have been known to swarm and bite animals in their path – there have been cases in horses that have been bitten hundreds of times,” he reports.

RELATED: Signs of Bee Stings in Dogs and What You Need to Know