A bite from a venomous snake is a medical emergency for a dog or cat. Vets in the United States see it often enough to call it a common emergency in some regions [1]. Venomous means the snake can inject a poison called venom.
If you think your dog or cat has been bitten by a snake, see your vet now.
Why it is urgent
Venom can harm the blood, blood vessels, muscles and other tissues, and some venoms also affect the heart or nerves [1]. Treatment works best when it starts early [2]. In a study of 59 dogs bitten by snakes in South Korea, dogs that reached the clinic later had more muscle damage and more body-wide inflammation than dogs seen sooner [3].
Size matters too. Vets have long worried that a small body receives more venom for its weight, which is one reason small and young pets need care fast [1].
In North America, most reported bites come from pit vipers, the group that includes rattlesnakes and water moccasins [1][2]. Coral snakes are the other venomous group found there [2].
Skin and wound signs
A pit viper bite often leaves two small puncture wounds, sometimes bleeding, with swelling around them [1]. Punctures are small, deep holes in the skin. In one group of puppies, swelling started at the muzzle and spread over the face, lips and eyelids [1].
In the South Korean study, every dog had signs at the bite site: swelling, bloody fluid from the wound, a change in skin color, open sores and, in some dogs, dead tissue [3]. Most bites were on the head or muzzle, followed by the front legs [3].
A thick coat can hide the bite marks, so you may not see them at all [2].
Bites that show few skin signs
Coral snakes belong to a family called elapids. Their venom mainly attacks the nerves that control muscles. This can cause weakness all over the body and can stop the muscles used for breathing [2]. Some elapid bites cause very little swelling at the bite [2], and signs can take hours to appear [2]. So a bite can be serious even when the skin looks nearly normal.
Damage that can follow
Signs can show up later, so a pet that seems fine at first still needs to be checked [1]. Tissue around a bite can die. Some dogs need surgery to remove dead tissue from the wound [3].
Other causes that can look like a snakebite
Swelling and small wounds can also come from other injuries, infections or stings. Only a vet can tell these apart.
Treatment
Your vet will advise on treatment for your pet.
When to see your vet
See your vet now if your dog or cat has:
- two small punctures or bite marks in the skin, which hair may hide [1][2];
- swelling around a bite, especially if it spreads [1][3];
- bleeding or bloody fluid from small wounds [1][3];
- skin that changes color around a wound [3];
- weakness or trouble breathing [2];
- any wound you think may be a snakebite, even if you are unsure.
See your vet if skin or tissue around an older bite gets worse, opens up or turns dark [3].
The bottom line
A venomous snakebite is an emergency. On a dog or cat it can show as punctures, swelling, bleeding and color change at the bite, but some bites show few skin signs. If you think your pet has been bitten by a snake, see your vet now.
This article is for general information only and does not replace advice from your veterinarian. If you think your dog or cat has been bitten by a snake, see your vet now.
Sources
- Southern CJ, Allen-Durrance AE, Schaer M. Pit viper envenomation in pediatric dogs: 5 cases. Clinical Case Reports. 2021;9:e05065. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC8588840/
- Morris CAD, Donaldson RE. Mechanical ventilation in snake envenomation of dogs and cats. Frontiers in Veterinary Science. 2023;10:1071257. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC10090310/
- Lee JM, Song JH, Song KH. A Retrospective Evaluation of Snake Envenomation in Dogs in South Korea (2004-2021). Toxins. 2022;14:565. CC BY 4.0. https://pmc.ncbi.nlm.nih.gov/articles/PMC9415592/