This question is about pets bitten by the snake common european viper/adder (vipera berus) https://en.wikipedia.org/wiki/Vipera_berus when a dog gets bitten by this snake the dog must get to a vet within 30 minutes for treatment because it might be deadly for dogs.

When a cat gets bitten by this snake it usually don't need to go to the vet unless it gets very sick (anaphylactic shock) if this happens you have little time to save the cat. What usually happens to a cat when bitten is this the area bitten swells a lot the cat has some pain and lays down to rest for 30 minutes to two hours depending on the amount of poison injected, and then the swelling goes down and the cat is back to normal.

A large dog can handle less snake venom then a tiny cat why is this?.

All of the five cats I have had during my life have been bitten by snakes some of them more then once and I never have taken any of them to the vet for this.I did call the vet the first time my cat got bitten but the vet told me I did not need to go there as cats have a partial immunity to viper venom.

I only have cats but I wonder why dogs have a stronger reaction to viper venom, every year there is warnings in the newspapers, what to do if your dog gets bitten by a snake.

Just to be safe always contact a vet if your animal get bitten by a snake.

  • '' A large dog can handle less snake venom then a tiny cat why is this?.'' I don't think this is true, but a large dog is obviously less flexible than a tiny cat making him get the full bite while the tiny cat may only get a scratch before jumping away, which makes the area swell then heal as if nothing happened. Commented Jun 29, 2017 at 5:10

3 Answers 3


Cats, dogs and people

Firstly I'd like to clarify the general facts between dogs and cats (and humans) and snake bites, before addressing the specific common european viper/adder (vipera berus) and where your assumptions are correct and incorrect.

The physiology between species varies, just as anatomy does. It this difference in physiology accounts for varying inter-species reactions. The different species react differently to different types of venom.

For example from the University of Adelaide:

../.. Though they can cause neurotoxic paralysis (muscle weakness, respiratory failure), this is uncommon to rare in humans, but common in domestic animals (cats, dogs). ../..

Different venoms have different effects on the victim. For example, some venoms act as anti-coagulants, some as neuro-toxins, some cause musle or kidney damage. As there's subtle physiological differences between the species, this accounts for the difference in reactions. Just as some medicine is safe for human use and not pets.

The funnel web spider is highly venomous and potentially lethal to human beings, but not dogs or cats.

What is the world's most dangerous spider?

The Australian funnel-web spiders are among the deadliest spiders in the world in the effect their bites have on humans and our primate relations (although the bite has little effect on dogs and cats).

The physiology of this is described well here: Why is funnel web spider venom so lethal to humans and not so much for other mammals?

Snakes can be lethal to both dogs and cats

Many snake bites can be venomous and lethal to cats. In Australia, for instance, there's many deadly snakes, that are lethal, not only to dogs and cats, but to humans.

From the RSPCA website:

The sort of reaction your pet has to a snake bite is determined by a number of factors: the type of snake, the amount of venom injected and the site of the snake bite. Generally the closer the bite is to the heart the quicker the venom spreads to the rest of the body. In addition, at the beginning of summer, snakes' venom glands are fuller and their bites are much more severe.

The assumption that cats are not being injected with venom (having dry bites) is not altogether true.

From the RSPCA website:

Dogs will often try to chase or kill snakes resulting in snake bites usually to the dog's face and legs. Cats, being hunters and chasing anything that moves, are also quite susceptible to snake bites.

Cats actually receive more snake anti venom than both humans or dogs in some areas.

From ABC News

Each spring humans are warned of the dangers of snakes coming out of hibernation, yet it is dogs and cats that receive more than 70 per cent of administered antivenom. .

"It’s the cats that we tend to see [which] have more of those interactions than the dogs," ../..

../.. cats may be at a higher risk of being bitten, ../..

The truth is, it's hard to obtain accurate statistics in some places about snake bite in our pets.

From Snake Bites and Dogs.

You won’t find details on the numbers of dogs bitten, or killed, by venomous snakes, though. I asked Michael Schaer, DVM, Professor of Veterinary Internal Medicine at the University of Florida, College of Veterinary Medicine, about the numbers of dogs bitten or killed by snakes in the U.S.

"I don't believe we have a valid source of information on the actual numbers of dogs bitten or killed by snakes annually in the United States," he explained, "because there is no central data resource for this."

Cats survive snake bites more than dogs

It seems that cats are hardier when it comes to snake bites. They take longer to react and have a better survival rate both with and without anti-venom.

From ABC News

While cats may be at a higher risk of being bitten, dogs are more susceptible to snake bites than cats, particularly to brown snakes, which are more prevalent in the southern areas of South Australia.

"A bite for a dog can be lethal in less than 30 minutes."

Cats have a greater resistance to snake bites, but will succumb to bites within 12 to 24 hours.

From Midland Vet Hospital

Cats tend to have milder signs than dogs. They will often present as being ‘dizzy’ with dilated pupils and no ability to blink. Dogs can have a rapid onset of signs and many owners often do not notice any signs before they collapse. 

Survival Rates:

90-95% of cats will survive a snake bite if treated with anti-venom. If not, the chance is 40-50%.

70% of dogs will survive with anti-venom, however only 5% of dogs will survive if not treated with antivenom

However cats are more likely than dogs to have allergic reactions to snake bites.

From ABC News

was more common for cats to have an allergic reaction to a bite.

Types of venomous snakes

From the Taxonomy of venomous snakes:

Around a quarter of all snake species are identified as being venomous.

In North America

Venomous snakes that your pet may be exposed to fall into two major categories: the crotalids and the elapids. Crotalids belong to the pit viper family and include snakes such as the copperheads, rattlesnakes, and water moccasins (also known as cottonmouths). .../... The elapids are the most deadly venomous snakes. Luckily, in North America the coral snake is the only member of this group.

It should also be noted that the cost of treating a pet with anti-venom is expensive and this may or may not affect veterinarian advice, as the treatment can extend to $2-3000.

The common european viper/adder (vipera berus)

The vipera berus, although it is a venomous snake, it is not a particularly dangerous snake. It doesn't account for many deaths.

What usually happens to a cat when bitten is this the area bitten swells a lot the cat has some pain and lays down to rest for 30 minutes to two hours depending on the amount of poison injected, and then the swelling goes down and the cat is back to normal.

This is what happens in most cases of dog, cat and human bites by this snake.

Treatment of bites by adders and exotic venomous snakes doi: 10.1136/bmj.331.7527.1244

UK poisons centres are consulted about an average of 100 human and a dozen veterinary cases each year. In about 70% of patients, envenoming is negligible or purely local, causing pain, swelling, and inflammation of the bitten digit. ../.. Only 14 fatalities have been reported since 1876 ../..

From the wikipedia link provided in the question:

Relatively speaking, bites from this species are not highly dangerous.

The potential for anaphylactic reaction and possible effects of the venom, is taken seriously, as although the risk is low, it's still dangerous and can cause the patient to become ill.

From the University of Adelaide:

Bites may cause mild to severe local effects, shock & coagulopathy. All cases should be managed as potentially severe. Shock should be monitored for and vigorously treated. Specific antivenom is available only for some Vipera species, but should be used in all but minor envenoming cases.

.../... All cases should be treated as urgent & potentially lethal. Rapid assessment & commencement of treatment including appropriate antivenom (if indicated & available) is mandatory. Admit all cases.

The common european viper/adder (vipera berus) and dogs

You describe the following symptoms if your cat is bitten by this snake.

when a dog gets bitten by this snake the dog must get to a vet within 30 minutes for treatment because it might be deadly for dogs.

As the poisons may be lethal to humans, it can also be lethal to dogs and cats. An anaphylactic (systemic) reaction can appear from 5 minutes or take many hours to show.

Treatment of bites by adders and exotic venomous snakes doi: 10.1136/bmj.331.7527.1244

Dramatic anaphylactoid symptoms may appear within five minutes of the bite ../.. or may be delayed for many hours.

This study indicates that the venom can make dogs sick, but is not necessarily lethal as suggested in your question; The effect of a single dose of prednisolone in dogs envenomated by Vipera berus – a randomized, double-blind, placebo-controlled clinical trial doi: 10.1186/s12917-015-0352-6:

.../... A total of 75 dogs bitten by Vipera berus within the previous 24 hours were included. .../... None of the dogs died during the study period.

It appears these dogs were not administered anti-venom.

This is the same reaction for both dogs and humans, but the symptoms last for longer. Unless of course there is an anaphylactic response in any of these species.

Treatment of bites by adders and exotic venomous snakes doi: 10.1136/bmj.331.7527.1244

Immediate sharp pain is followed, usually within a few minutes but sometimes up to more than 30 minutes later, by a sensation of tingling and local swelling that spreads proximally. Local blisters containing blood are uncommon. Spreading pain, tenderness, inflammation (often described misleadingly as “cellulitis,” although there is no infection), and tender enlargement of regional lymph nodes are sometimes noticeable within hours. Reddish lymphangitic lines and bruising appear, and the whole limb may become swollen and bruised within 24 hours (fig 2) with involvement of the trunk and, in children, the whole body ../..

I cannot find any definitive difference between the reactions of dogs and cats and this particular snake bite, beyond the generalisation that cats tend to survive snake bites more so than dogs.

As for this statement:

A large dog can handle less snake venom then a tiny cat why is this?.

There is no where I can find evidence of this assertion. Toxicity usually correlates with the amount of toxin, time of year, site of the bite and size of the animal across the species.

From Merck Vet Manual:

Fatal snakebites are more common in dogs than in other domestic animals. Because of the relatively small size of some dogs in proportion to the amount of venom injected, the bite of even a small snake may be fatal. In dogs and cats, mortality is generally higher in bites to the thorax or abdomen than bites to the head or extremities. .../...

note they are comparing dog sizes to livestock.

The venom affects several physiological pathways Biological and biochemical activities of Vipera berus (European viper) venom.:

Vipera berus venom displayed in vitro proteolytic, fibrinolytic, anticoagulant, and phospholipase A2 activities.

As for the exact physiological mechanism that differ between dogs and cats, I have not been able to isolate that (currently not having access to journals makes this difficult) and such a detailed review may be a better fit on Biology.Se.

  • 2
    thank you for the answer and the time used to find all this information. Commented Jun 7, 2017 at 4:58
  • @trondhansen you're welcome. I am disappointed that I couldn't source the physiological differences easily. I will attempt to.. a bit of a perfectionist. If I find something I'll update and ping you.
    – user6796
    Commented Jun 7, 2017 at 5:00

So, I'd like to answer your question as best that I can but I may not have all the answers... More like concepts that are to be considered. Where I'm from in Wilmington, NC, USA, we have pit vipers including rattle snakes, copperheads and water moccasins.

I was a vet tech for years and people would bring their pets in all the time with bites from vipers.

Two possibilities of what I'm thinking when I read your question: There is a such a thing as dry bites. Bites where the snake did not inject venom. I would assume cats generally being smaller than dogs, and daintier on their feet than dogs that a dry bite may be given in warning, because they're less of a threat to the snake.

The other possibility-- we had a dog come in that had been bitten by a rattlesnake for the second time. He had little to no reaction, and the conclusion was that the antibodies from the initial antivenom treatment was still active in his body (his puncture wounds and oozing were deep enough we knew it wasn't a dry bite). This being an experience we had at my clinic, it makes me wonder if animals who live through a bite, then have enough antibodies in their body to protect them from future bites.

I'm sorry if this does not answer your question, I answered it more as if you were asking "why didn't my cat react to a European Viper Bite", not as generalized in all cats.

The protocol where you are from may also be different in how to react to animals and different species.

I hope you find the correct answer to this. I'd be curious to see if anyone comes up with some info behind this. Cats and dogs have basically the same cardiovascular and nervous system, in which venom is transferred and affects, so I don't understand how it'd be two different reactions, medically.

  • thank you for the answer,just to be clear always contact a vet if an animal gets bitten by a snake. i know abut dry bites from snakes but the swelling of the bite area sugest atleast some venom has been injected,i have some theories about the different reactions from viper venom in cats and dogs,but it is interesting to see what others think,i cant mark your answer as solved but i gave an upvote for trying. Commented Jun 5, 2017 at 6:19

Cats are famous for having very thick skin so maybe the snake cannot puncture very deep into the flesh and the venom is only inserted into/under the skin, not into the muscles. If the venom is not into the muscles (where the big blood vessels are) it is not carried immediately to the organs. This gives time to the organism to fight against the poison (or you to go to the vet).

Also the cats react much much faster than dogs or humans, so they could jump away when they feel the teeth penetrating the skin. So the snake won't have enough time to inject a full dose.

Disclaimer: I am not a specialist. it is just my amateur-grade opinion.
Interesting article: What to do if your cat is bitten: http://www.wikihow.com/Treat-a-Cat-for-Snakebite

  • 2
    you are right this might be a part of the explanation. Commented Jun 5, 2017 at 12:34
  • are you able to offer a reference for the claim cats have thick skin? It's preferred to have evidence when making claims like these. Thanks
    – user6796
    Commented Jun 6, 2017 at 23:54
  • "Depending on the species and age, the skin may be 12 to 24% of a cat’s body weight" - 24% is an impressive number!!! - merckvetmanual.com/cat-owners/skin-disorders-of-cats/…
    – IceCold
    Commented Jun 7, 2017 at 9:53
  • @YvetteColomb-Also a friend of mine that is veterinary stated that and I have been there to see how hard he had to push into the syringe to penetrate the skin.
    – IceCold
    Commented Jun 7, 2017 at 10:00
  • it is a nice link you provide in your answer but it dont answer my question about the difference of reaction in cats and dogs. Commented Jun 7, 2017 at 14:22

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