At a glance
Symptoms of snakebite toxicity: Cats are bitten most often on the face and legs, symptoms can vary depending on the species, but may include:
Cats are hunters by nature and unfortunately not able to discriminate between harmful prey and non-harmful prey. Many housecats will think nothing of chasing down and attacking a snake, not realising how much danger they are putting themselves in.
There are poisonous snakes throughout the world, and it would be too hard to list poisonous snakes country by country, so this article will aim to provide general information on snake bites, but not snake species-specific to any one country.
The most common snake bites to occur in cats in Australia are from the Eastern brown snake, tiger snake, death adder, copperhead, black snake and the red-bellied black snake.
Venomous snakes in the United States can include the copperhead, rattlesnake, cottonmouth, coral snake.
The majority of snake bites occur on the cat’s head, neck, and legs. Bites on the body can happen and tend to be more dangerous; the closer to the heart, the quicker the venom can travel around the body and the more dangerous.
Where and when can snakes be found?
Snakes are more prevalent in the warmer months of spring and summer, but in some areas, they can be found year-round. We have had a red-bellied black snake in our garden in June (which is winter in Sydney, Australia). As snakes are cold-blooded, they need the heat of their surroundings to warm up.
One snake catcher I spoke to told me the following…
‘Between 10 am and 4 pm is generally when they are out. Red-bellied black snakes optimal temp is 24 to 28 and Eastern Brown Snakes are 28 to 32. You will normally see them basking in a sunny position.’
But I need to reiterate; it is still possible for them to be out during other hours of the day (I encountered a red-bellied black snake yesterday at 8 am during my walk with the dog). It is common to find snakes close to the water of creeks or dams. When not sunning or hunting, they like to hide under rocks and logs and in dense shrubbery and long grasses.
Difference between a venomous and non-venomous snake
Most (but not all) venomous snake has elliptical pupils (slit-like, like a cat) and a triangular or diamond-shaped head. A non-venomous snake has round pupils and a rounded head. Even non-venomous snakes have teeth and will bite, and while they may not poison the cat, the bite can cause pain and infection.
Contrary to popular belief, pythons and boa constrictors kill their prey by cutting off the blood supply and not by suffocation. By coiling themselves and squeezing tight, the heart doesn’t have enough strength to circulate blood against the pressure created by the snake. This is a far quicker and more efficient way to kill than by suffocation.
Can cats kill snakes?
Yes, a cat can kill a small snake, but it’s not something you should allow your cat to do. Even small, non-venomous snakes have the potential to inflict damage on a cat through biting. As much as I don’t personally like snakes, they serve an important ecological role in our environment. Do not encourage cats to hunt any wildlife, including snakes.
Even small pythons can quite easily kill a small dog or cat. Baby venomous snakes are still able to inject venom, and non-venomous snakes will still bite a potential threat that can be extremely painful and lead to infection.
If you do have a snake problem in your area, there are more effective ways to reduce numbers by making changes to your environment to make it less snake-friendly (such as moving woodpiles away from the home), or calling in a snake catcher to relocate a snake.
What is snake venom and what does it do?
Venom is modified saliva, which is stored in sacs behind the eye on each side of the head. It contains zootoxins (toxins produced by an animal) which the snake injects into the skin via the hollow fangs in the snake’s mouth. It is used as a defensive mechanism against predators and to kill and digest the snake’s prey.
Venom can vary depending on the species and may contain toxins that affect the blood (hemotoxins), certain cells (cytotoxins) and the nervous system (neurotoxins). The main function of venom is to kill prey the snake is hunting as well as protect the snake against predators.
Snakes can control the amount of venom is injected and in some cases may not inject any, this is known as a dry bite. Of course, it goes without saying that if your cat has been bitten by a snake, immediate veterinary attention is essential as you have no way of knowing if or how much venom has been injected.
Snake bites can affect various organ systems. Breathing difficulty, acute kidney failure (nephrotoxicity), bleeding disorders, paralysis (including the respiratory system), tissue necrosis (death) and severe allergic reaction. There are four types of snake venom:
Neurotoxins: Neurotoxins work on the nervous system and brain; they block nerve impulses, which leads to paralysis.
Hemotoxins: These toxins destroy red blood cells (hemolysis), lower blood pressure and disrupt blood clotting by destroying platelets which are non-nucleated cell fragments that form a clump to plug a damaged blood vessel as well as removing fibrinogen, which helps to mesh the platelet plug, resulting in internal bleeding.
Cytotoxins: Cytotoxins destroy tissue, usually specific cells, usually those of an organ such as kidney cells (nephrotoxins). Rattlesnake venom is cytotoxic and associated with soft tissue necrosis (death).
Myotoxins: Mycotoxins destroy skeletal muscle cells, the break down of muscle fibre releases myoglobin (a protein in the muscle cells) into the blood plasma results in rhabdomyolysis, which can seriously damage the kidneys.
What is antivenom?
Antivenom (also known as antivenin) is used to counteract the effects of venom. It is obtained by ‘milking’ snakes of their venom, which is diluted and a small amount is injected into horses or sheep. These animals mount an immune response, producing antibodies against the venom. Antibodies bind to the venom, thus neutralising it. However, they are not able to reverse the damage already done. This is why it is so important to seek immediate veterinary treatment.
There can be considerable variables with snake bites:
- Species and size of the snake
- Age of the cat (kittens and senior cats are at increased risk)
- Underlying medical conditions
- Amount of subcutaneous fat and thickness of fur
- Number and location of the bite(s)
- If the cat has been bitten previously (a repeat bite can cause a severe allergic reaction)
- Microbes in the snake’s mouth
Puncture wounds may not necessarily be apparent; they are either hidden by the fur or due to localised swelling. So don’t assume that the absence of puncture marks means your cat has not been bitten by a snake. The most common areas cats are bitten are the face, neck, chest, and forelimbs.
Two stages develop after a snake bite, pre-paralytic and paralytic. Symptoms can develop between a few minutes to 24 hours after being bitten and may include:
- Fang marks and/or swelling at the location of the bite
- Dilated pupils
- Ptosis (drooping eyelids)
- Photophobia (sensitivity to light)
- Increased respiration
- There may or may not be extreme pain, hemotoxins are extremely painful but are slower acting, neurotoxins are relatively pain-free but faster acting.
- Dilated (large) pupils (mydriasis) and fixed pupils which don’t respond to light, usually the pupils constrict (become smaller) due to increased light
- Muscle weakness
- Change in meow
- In-coordination (drunken gait)
- Rapid pulse and heartbeat
- Difficulty breathing or increased/shallow breaths (tachypnea)
- Blue-tinged gums from lack of oxygen
- Blood in the urine (hematuria) due to coagulation dysfunction
- Tea coloured urine (due to the breakdown of muscles)
- Paralysis starts at the back legs and moves towards the cat’s head
It is important to repeat that not all signs will be present; they may also wax and wane.
Any snake bite needs immediate veterinary attention, call ahead to let them know you are on your way so that they can prepare for the cat’s arrival or refer you to another hospital if they do not have antivenom on hand.
Why a cat must stay still:
- Toxicity occurs at the site of the bite as well as throughout the body (systemic). Snake venom is injected under the skin or into the muscle and is released into the interstitial space, (fluid-filled areas that surround the cells).
- Blood vessels which circulate blood throughout the body (systemic circulation), cannot absorb large molecules (of many snake venoms) through their endothelium (cells that line the interior surface of blood vessels and lymphatic vessels), but the lymph vessel (thin-walled tubes, that carry lymph) endothelium can.
- Snake venom enters the systemic circulation when lymph enters the bloodstream at the subclavian vein, via the thoracic duct. Unlike blood, which is continually pumped around the body via the heart, the lymphatic system works differently. Lymph circulates with the movement of muscles. Therefore, immobilisation of the muscles helps to slow down the movement of snake venom through the lymphatic system and into the systemic circulation.
If you have a person to help you, do the following below on the way to the veterinarian:
- Remove the cat’s collar.
- Keep the bitten area lower than the heart.
- Pressure immobilisation technique (PIT): Apply a pressure bandage over the affected area. The goal is to slow down venom spreading to the systemic circulation via the lymphatic system by immobilisation of the area to prevent the pumping action of the skeletal muscles and slowing down lymphatic drainage.
- Keep the cat quiet and calm; a rapid heart rate will help the venom to move more quickly around the body.
- If there is no heartbeat or pulse, administer CPR.
This should only be carried out if there’s more than one person. It is better to drive your cat straight to the veterinary practice than waste additional time and delaying urgent medical treatment.
Be careful when handling a cat who has been bitten, they are usually in a lot of pain and may lash out.
- Allow your cat to walk
- Cut the bitten area
- Attempt to suck the venom out of the bite (this will increase blood flow to the area)
- Apply a tourniquet
- Attempt to catch or kill the snake
- Apply ice
- Delay treatment
Treatment is aimed at reversing the effects of the venom as well as treating symptoms. The veterinarian will use a snake venom test kit to determine the kind of snake that has bitten your cat as well as other tests to evaluate your cat, which may include:
- Biochemical profile, complete blood count, and urinalysis
- Check blood pressure
- Blood smear to evaluate the red blood cells
- Clotting time, to measure how long it takes a sample of the cat’s blood to clot (normal clotting time is <165 seconds)
- Once the type of snakebite has been determined, the veterinarian will administer the appropriate antivenom. Some cats will need multiple vials of antivenom during treatment. Occasionally a cat will have an allergic reaction to the antivenom although this is more common in dogs than cats.
- Intravenous fluids to maintain blood pressure and help protect the kidneys from toxins and maintain cardiac output.
- To reduce your cat’s chances of having an allergic reaction to the antivenom, your veterinarian may also administer antihistamines, steroids, and adrenaline before giving your cat the antivenom.
- Oxygen therapy or if the cat is unable to breathe on his own, he will be placed on a ventilator to breathe for him.
- A feeding tube may be required if your cat is unable to eat due to muscle paralysis.
- Cats suffering from paralysis will need to have their bladder manually expressed until they can urinate on their own.
- Antibiotics to treat secondary infections.
- Analgesics may be necessary to treat pain.
When can my cat come home?
This depends on the severity of the emergency and how quickly treatment began. The earlier he receives antivenom, the better. All cats respond differently to treatment.
Some cats may be able to come home in as little as 24 hours after treatment, as soon as they can eat, drink, go to the toilet and eat on their own. Some cats may take a little longer to recover, and it may be several days.
Cats who have been discharged from the hospital need some recovery time; they should be kept quiet, calm and indoors during this period.
Can a cat survive a snake bite?
If the cat receives prompt veterinary attention, the prognosis is good, between 80-90% of cats who receive antivenom will survive a snake bite.
Can I give Benadryl to a cat who has been bitten by a snake?
No, Benadryl and other antihistamines block the action of histamines, which are responsible for allergy-related symptoms. Symptoms related to a snake bite are due to the action of the venom on various body systems, and Benadryl will not affect this.
Administer all medications as instructed by your veterinarian.
Keep your cat indoors while he recovers.
Please be aware that antivenom doesn’t offer your cat lifetime protection from snake bites. It is not a vaccine and only works during that particular exposure, not against future snake bites.
Deterring snakes from the garden
The best way to avoid snakes in your garden is to provide an environment that isn’t attractive to snakes.
- Maintain your garden, so that is free of overgrown plants, regularly mow the lawn.
- Keep the garden free of debris, such as corrugated iron, building materials, overgrown weeds, old junk etc
- When installing fences, dig them at least 8-12 inches into the ground.
- Don’t leave containers of water lying around.
- If you have a shed, keep it free or rodents.
- Remove fallen fruit from the ground as this encourages rodents, which will, in turn, encourage snakes.
- Avoid woodpiles, especially in the summer months. If you do have a woodpile, make sure it is well away from your house and not accessible to your cats or children.
- Avoid rockeries, which provide excellent habitat for snakes to hide.
What to do if you find a snake in the garden
Bring all pets indoors and shut doors and windows.
Contact your local wildlife authority (WIRES in Australia) or a licensed snake catcher. Do not attempt to catch or kill the snake.