How to Treat Snake Bites in Horses

Life Out Here comes with the risk of unwanted visitors in your horse’s barn or turnout areas, including pests such as snakes. While some snake bites may cause only localized swelling, others, particularly from venomous snakes, can become medical emergencies that warrant immediate veterinary attention. Knowing what to look for and how to respond is critical to your animal’s health and recovery.

What Are Snake Bites in Horses, and Are They Dangerous?

Snake bites occur when a snake bites a horse, potentially injecting venom through its fangs (snake envenomation), depending on the specific snake. The severity of the bite can range from mild, local inflammation and temporary lameness to severe, potentially life-threatening symptoms. The seriousness of snake bites depends on several factors, such as the type of snake (venomous or not), the amount of venom injected, the location of the bite and the horse’s individual response. 

Snake bites are a relatively common emergency in horses. Bites occur most often in warmer months, when snakes are most active. The annual number of snake bites in horses is widely debated, as data on the exact figure is limited. This is largely due to incidents going unconfirmed or not reported. When a horse is bitten, it usually occurs on the face or lower limbs when it encounters a snake while grazing in pastures or exploring its surroundings.

Which Snake Species Are the Biggest Threat to Horses?

Pit vipers, which include rattlesnakes, copperheads and cottonmouths, are the leading cause of snake envenomation in horses in the United States:

• Rattlesnakes: Rattlesnakes are the most widespread venomous snakes in the United States, with the greatest variety of species in the Southwest, and they are a leading cause of snake bites in horses.  

• Copperheads: Mostly found in the Eastern and Central United States, copperhead snakes are capable of causing painful swelling and tissue damage. 

• Cottonmouths (water moccasins): Found in the Southeastern and South-Central United States, including Texas, these snakes make their homes near water sources and damp pastures. 

These snakes have the ability to determine whether to emit venom during a bite. They use special muscles around their venom glands to choose whether to release a large dose, a small amount or no venom at all (dry bite). A snake typically bites a horse defensively, after being startled or stepped on. 

How Does Snake Venom Affect a Horse?

Snake bites are especially dangerous when venom is injected. At the time of the bite, toxic compounds enter the bloodstream through the bite wound. The venom can contain anywhere from 20 to over 100 chemical components, depending on the species of snake. Snake venom contains either neurotoxic peptides or a complex mixture of proteins and enzymes, all of which can cause nervous system damage, necrosis (tissue death), heart and lung damage and abnormal blood clotting.   

What Are Signs of Snake Bites in Horses?

Depending on the location and the severity of the bite, snake bites in horses can look very different from case to case. Some horses develop obvious symptoms, such as swelling and pain, while others only show subtle changes at first.

Common signs a horse has been bitten by a snake include:

• Sudden swelling: In many cases of snake bites in horses, swelling develops around the bite site and can become quite pronounced, particularly if it occurs on the face or around the horse’s muzzle. 

• Puncture wounds: A snake bite will leave behind one or more small puncture marks, although they are often challenging to see beneath the horse’s hair.  

• Pain or sensitivity: The snake bite can cause the horse significant pain, causing it to flinch, become restless or resist having the affected area touched. 

• Bleeding or bruising: The bite area may bleed or develop discoloration. 

• Difficulty breathing: A snake bite that causes swelling around the muzzle, throat or neck can interfere with the horse’s airway, causing significant trouble breathing. This symptom requires immediate attention from a veterinarian. 

• Weakness or unusual behavior: After a snake bite, the horse may become lethargic, unsteady, anxious or generally appear unwell.  

• Excessive sweating or trembling: The horse may exhibit these symptoms as a response to the pain or stress of the bite, as well as the effects of the venom. 

• Drooling or trouble eating or swallowing: These signs are most common when the snake bite occurs near the head or throat area. In rare cases, swelling can lead to difficulty drinking, causing water to enter the horse’s lungs, which can develop into pneumonia. 

Not all symptoms are obvious immediately following a snake bite, and the effects can be much more serious than what you see. Because of this, all suspected snake bites should be treated as a veterinary emergency. 

How Do Vets Confirm Snake Bites?

Diagnosing a snake bite in a horse can be challenging because the bite marks may be small or difficult to find, and symptoms can resemble other equine injuries or illnesses, such as infections, allergic reactions and spider envenomation. Veterinarians typically use a combination of the horse’s history, physical examination and clinical signs to determine the correct diagnosis.

While examining the horse, your vet may do the following:

• Ask about the incident: Crucial details, such as when a snake bite was suspected, where the horse was and whether snakes have been seen nearby, provide useful insight for accurate diagnosis. 

• Inspect the horse for bite wounds: The veterinarian will carefully and gently examine the horse for punctures, swelling, bruising, bleeding or other abnormalities associated with a snake bite.  

• Assess vital signs: Heart rate, breathing rate, temperature, gum color and overall behavior are critical metrics that help the vet determine the severity of snake bite symptoms. 

• Evaluate swelling and pain: The veterinarian will evaluate the seriousness of swelling, particularly if it occurs on the face, muzzle, throat or other areas that threaten the airway. 

• Check for signs of venom effects: Weakness, abnormal breathing, changes in circulation or other systemic abnormalities may indicate snake envenomation. 

• Perform additional testing: In some cases, bloodwork (complete blood count) and additional diagnostic tests, including urinalysis and clotting time tests, may be used to evaluate the horse’s overall condition, rule out other conditions and identify complications. 

How Are Horses with Snake Bites Treated?

Treatment for a snake bite in a horse is critical, and any case should be treated as an emergency due to the risk of envenomation. A snake’s venom can begin causing tissue and systemic damage quickly after being injected into the horse’s bloodstream. With prompt veterinary treatment, most horses recover. Prognosis depends on the type of snake, the amount of venom injected, the location of the bite and how quickly treatment begins, and bites to the muzzle or throat carry the added risk of airway swelling. Swelling often peaks within a day or two and then gradually decreases. Long-term neurological and cardiovascular complications can occur but are rare. 

Immediate Veterinary Care

A horse owner’s priority is to arrange veterinary care while keeping the horse calm. Do not delay professional care while attempting home remedies or trying to determine the severity of the injury. A veterinarian will assess the horse’s airway, breathing, circulation, vital signs and overall condition. Horses with swelling around the muzzle or throat may require close monitoring to prevent upper-airway obstruction from becoming life-threatening. 

When swelling threatens the airway, veterinarians often place soft tubes in the nostrils to keep air moving. If swelling continues to block breathing, an emergency tracheotomy (a surgical opening in the windpipe) may be needed to establish a clear airway. Your veterinarian will tell you what to do while they are on the way. You can also use a digital thermometer for livestock, such as Producer's Pride Digital Veterinary Thermometer, Fahrenheit, to report the horse’s temperature to the veterinarian while waiting for care. 

Antivenom

When available and necessary, antivenom is administered to neutralize the snake venom. Antivenom is generally most effective when administered early. The number of vials needed, and whether repeat doses are required, depend on the product, the severity of the bite and how the horse responds, so the veterinarian determines dosing. 

Antivenom is not necessary for every snake bite, and its availability varies by region and snake species. Because reactions to antivenom can occur, it should only be administered and monitored by a veterinarian. 

Fluids and Supportive Care

A major part of treatment is supportive care while the horse’s body processes the venom. Depending on the horse’s condition, this can include intravenous (IV) fluids to help support circulation, management of shock, stall rest, oxygen or respiratory support and close monitoring of cardiovascular function. More severely affected horses may require hospitalization and advanced levels of care. 

Managing Swelling and Tissue Damage

Local swelling and tissue injury can continue to develop after the initial bite. Your vet may clip the hair around the wound, clean the area and monitor the progression of swelling and tissue damage. Leading edges of swelling may be marked at intervals to track progress. 

Nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to control pain and swelling. Because venom can interfere with blood clotting and platelet counts, your veterinarian decides whether and when to give them, and some veterinarians wait until blood work has been checked or until about a day after the bite. Never give an NSAID before speaking with your veterinarian. 

Significant tissue damage can take time to develop. In some cases, damaged tissue may eventually become necrotic (dead or dying), requiring prolonged wound care. Surgical removal of damaged tissue is generally not performed immediately unless there is a specific indication. The reason for the delay is that the full extent of tissue injury is not always apparent early on. When appropriate, surgical debridement to remove dead or damaged tissue may be performed to allow healthy, blood-supplied tissue to grow.

Pain Control and Wound Care

Snake bites can cause painful injuries, so your veterinarian may provide necessary pain relief. Antibiotics may be considered when there is substantial tissue necrosis or significant risk of secondary infection. The vet may also evaluate the horse’s tetanus protection and provide necessary prophylaxis (vaccine) when indicated. 

Can Snake Bites Be Prevented?

While it is not possible to completely remove the risk of snake bites in horses, there are several actions you can take to reduce the threat, such as:

• Keep pasture and turnout areas maintained: Regularly inspect your horse’s pasture, paddocks and turnout areas for places where snakes may seek shelter. Keep grass and weeds managed, and remove brush piles, fallen branches, piles of lumber, old equipment, trash and other debris that create hiding places for snakes. 

• Reduce rodent attractions: Many snakes prey on rodents, so reducing the food and shelter available to rodents can make your property less appealing to snakes. Keep horse feed in secure containers, clean spills promptly and use rodent traps around barns and feed rooms. One recommendation is the Tomcat Rat and Mice Bait Station, which is tamper-resistant to a degree but not dog-proof, so pets must be supervised where it is used and the label’s placement directions must be followed. 

• Take seasonal activity into account: Snake activity varies by species and region, but encounters are typically more common during warmer months. Before turning horses into a pasture, walk through the area and inspect it for snakes or potential hiding spots. 

• Talk to your vet about vaccination: The AAEP lists a Western diamondback rattlesnake (Crotalus atrox) toxoid vaccine as a risk-based option for horses that live in or travel to areas where venomous snakes are a concern. The vaccine carries a conditional license, offers partial or no protection against some species (it does not cover cottonmouths) and does not replace emergency veterinary care.