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Local anesthetics are among the most commonly used medications in equine veterinary medicine. These drugs temporarily block nerve conduction, preventing pain signals from traveling from a specific area of the body to the brain.
By providing targeted pain relief without causing unconsciousness, local anesthetics allow veterinarians to perform a wide range of diagnostic and therapeutic procedures safely and effectively.
In horses, local anesthetics are used for numerous procedures, from routine wound repair and dental care to complex surgeries and lameness examinations. Several local anesthetic drugs are available for use in horses, including lidocaine, mepivacaine, and bupivacaine. Veterinarians select the most appropriate drug based on the procedure being performed, the desired duration of pain control, and the horse’s individual needs.
Keep reading to learn more about the most common local anesthetics used in horses, their clinical applications, safety considerations, and regulations governing their use in competition animals.
Local Anesthetics for Horses
Local anesthetics are a class of medications used to temporarily block pain and sensation in a specific area of the body. They are commonly used in equine practice for minor surgical procedures, wound repair, lameness diagnostics, nerve and joint blocks, dental procedures, and other interventions where localized numbing is needed.
These medications work by interrupting nerve signal transmission near the treatment site. When the nerve cannot carry pain signals normally, the area becomes numb while the rest of the horse remains awake and responsive. Depending on the procedure, local anesthetics may be used on their own or combined with sedation, restraint, or other pain management strategies.
There are a variety of local anesthetics available, each with a different duration of action and time to onset of numbing.
This allows veterinarians to select the most appropriate anesthetic based on the location being treated, the expected length of the procedure, the need for diagnostic accuracy, and the horse’s overall condition. Some local anesthetics may provide numbing for 12 hours or more. [1]
Table 1. Clinical features of local anesthetics used in equine medicine [2]
| Local anesthetic | Time to onset | Duration of numbing |
|---|---|---|
| Lidocaine | 5 – 10 minutes | 60 – 90 minutes |
| Mepivacaine | 5 – 10 minutes | 120 – 180 minutes |
| Bupivacaine | 10 – 30 minutes | 240 – 480 minutes |
| Ropivacaine | 10 – 30 minutes | 240 – 480 minutes |
Shorter-acting anesthetics, such as lidocaine, are often useful when rapid onset is important and prolonged numbness is not required. Longer-acting options, such as bupivacaine or ropivacaine, may be selected when extended pain relief is needed after a procedure.
Mepivacaine is commonly used in diagnostic lameness work because it has a relatively rapid onset and an intermediate duration of action.
The choice of local anesthetic also depends on safety considerations. Dose, injection site, tissue health, proximity to nerves or blood vessels, and the horse’s medical status can all influence how a local anesthetic is used.
Available Forms
Local anesthetics can either be applied topically (to the surface of a tissue) or injected subcutaneously (below the skin). [1] Topical forms are typically liquids, patches, ointments, gels, sprays, or creams, depending on the tissue being treated. [2][3] Injectable forms come in sterile liquid solutions.
The most common local anesthetics used in equine practice are: [2][3]
- Lidocaine (Lignocaine®, Xylocaine®, Akten®)
- Mepivacaine (Carbocaine®, Intra-Epicaine®, Vetacaine®)
- Bupivacaine (Marcaine®)
- Ropivacaine (Naropin®)
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Drug Class: Local Anesthetics
Local anesthetics are medications that temporarily block sensation in a specific region of the body. In horses, they are used to provide localized pain control for procedures such as wound repair, minor surgery, dental work, nerve blocks, joint blocks, and diagnostic lameness examinations.
Unlike general anesthetics, local anesthetics do not make the horse unconscious. Instead, they prevent pain or sensation from being transmitted from the treated area to the brain. Depending on the situation, local anesthetics may be used alone or alongside sedation, physical restraint, anti-inflammatory medications, or other pain management strategies. [2]
Because local anesthetics can affect nerves, muscles, the cardiovascular system, and the central nervous system if used incorrectly or absorbed in excessive amounts, they must be dosed and administered carefully by a veterinarian.
Mechanism of Action
Local anesthetics primarily work by blocking nerve signaling. [1][2] When a stimulus, such as pain, touch, or temperature, is applied to a tissue, nerves fire to signal to the brain that there is a sensation occurring. During this nerve firing, sodium channels open and allow sodium to enter the nerve cell, producing an electrical signal.
Local anesthetics bind to sodium channels and reduce movement of sodium, preventing the electrical signal from firing. Without nerve firing, there is no signal to the brain that sensation or pain has occurred. [2]
Local anesthetics can also affect the central nervous system (CNS). By inhibiting nerve signaling in the spinal cord, pain or sensation signals never reach the brain. This prevents the animal from feeling a sensation, even if the nerves at the affected site fire appropriately. [2]
There are two main types of nerve fibers in tissues: sensory and motor fibers. Sensory fibers detect temperature changes, pain, and touch. Motor fibers provide information about proprioception (orientation of the animal in its environment) as well as stimulate muscles and other tissues to contract, producing movement. After application of a local anesthetic, both types of fibers may be affected. [2]
Generally, sensory fibers are numbed first, which allows veterinarians to perform painful procedures on a particular area. With additional time or higher volumes of local anesthetic, motor function is affected. [2] This relaxes the tissues and allows for easier manipulation by the veterinarian. For example, a veterinarian may perform a motor nerve block of the eyelids to facilitate a procedure requiring the horse’s eye to stay open.
Uses in Horses
Local anesthetics are used for a variety of procedures in veterinary medicine where pain relief and numbing are desirable.
Common uses in horses include: [2]
- Injection around a specific nerve to numb the area or reduce muscle movement. This type of administration is commonly used for lameness examinations, dental procedures, and eye procedures.
- Injection into a joint for lameness examination or to reduce pain after a surgical procedure.
- Epidural injection to reduce straining and pain in obstetric procedures like dystocia (difficulty giving birth).
- Local tissue infiltration to facilitate treatment of wounds or injuries.
- Topical administration to the skin to reduce reactivity to needles or other procedures.
- Topical administration on the eye to facilitate ocular procedures or reduce pain.
For most procedures, lidocaine and mepivacaine are the local anesthetics of choice due to their rapid onset time. They are commonly used for nerve blocks, tissue infiltration, and epidurals. Bupivacaine and ropivacaine are more commonly used in procedures where a long duration of action is necessary, such as during surgeries. [2]
Lidocaine can also be used intravenously (into a vein) to treat conditions like heart arrhythmias and poor intestinal motility. [2] It can also help reduce the quantity of other general anesthetic medications required during surgical procedures. [2]
Administration Routes
Veterinarians typically inject local anesthetics into the desired tissue to ensure maximal effect on the sensory and motor nerve fibers. These injections are typically subcutaneous (under the skin), allowing the injected liquid to coat the nerve and numb it completely. This method of administration is used for wound care, lameness examinations, standing surgeries, and other procedures. [2]
Similarly, veterinarians may inject local anesthetics as an epidural. Epidural injections introduce the anesthetic around the spinal cord to numb major nerves at their source. [2]
Epidurals are most commonly used for obstetric procedures, such as during a difficult foaling, as they prevent the mare from straining her muscles against the veterinarian. In some cases, veterinarians may use an epidural for rectal palpation if a horse strains significantly against the procedure.
In some cases, topical ointments, creams, or lotions may be used to numb small patches of skin for procedures like injections. This can reduce the horse’s reactivity to the procedure, reducing stress and improving safety for handlers.
Topical preparations are also available to apply to the eye surface, allowing for easier manipulation of the eye.
Dosage
The dose of local anesthetic used depends on multiple factors, including: [2]
- Location to be numbed
- Type of local anesthetic
- Format used (injectable, cream, etc.)
- Whether pain/sensation or motor function needs to be reduced
- Toxic dose for the specific local anesthetic
Before performing a procedure, the veterinarian calculates the maximum amount of the medication they can give the horse before causing toxicosis.
If the calculated dose is too little for the desired procedure, they may choose an alternative local anesthetic with a higher safety profile. Of the major local anesthetics, bupivacaine has the lowest toxic dose, at around 2 mg/kg of body weight. [2]
In general, veterinarians use as little of the local anesthetic as they can to produce the desired effect. Most nerve blocks are less than 20 mL in volume, or 400 mg. [2] However, if multiple areas must be numbed, such as for a lameness examination, the total volume of local anesthetic can add up quickly, and may put the horse at risk of toxicosis.
Storage
Local anesthetics should be kept at room temperature. Avoid freezing. [3] Always follow the label storage directions and keep out of reach from children and animals.
Safety Warnings & Precautions
Since local anesthetics are not given systemically (to the whole body), they are safe drugs with minimal risk of side effects.
Monitoring
There are limited monitoring requirements for local anesthetics. Veterinarians test whether there is adequate numbing of the tissue by poking the area with a blunt object such as a pen before starting the required procedure.
If the horse reacts, there is inadequate numbing of the sensory fibers and the horse can feel painful stimuli. In this case, they can either wait longer for the anesthetic to numb more fibers, or they can administer more local anesthetic. For procedures where the local anesthetic is used to reduce muscle movement, paralysis or loss of function of the tissue indicates an effective block. [3]
During the procedure, the veterinarian continues to monitor the horse for signs of reactivity to painful stimuli. If the horse becomes reactive, they can administer more local anesthetic to improve the quality of the block.
Contraindications
Contraindications refer to circumstances where a drug should be avoided or used with caution.
Local anesthetics should not be given to animals with a previous history of hypersensitivity to these medications.
Accidental systemic administration of local anesthetics may cause serious side effects in animals with underlying health conditions, such as: [3]
- Liver or kidney disease
- Heart arrhythmias
- Heart disease affecting heart function and contractility
To avoid systemic administration, veterinarians withdraw on the syringe plunger prior to injection to ensure the needle is not within a blood vessel.
Side Effects
Local anesthetics have minimal risk of side effects when administered properly. Rarely, local anesthetics may enter the bloodstream if a vessel is punctured during administration. In these cases, side effects are more likely due to distribution of the medication to the animal’s entire body. [3]
Potential side effects from systemic administration of local anesthetics include: [3]
- Lethargy or drowsiness
- Uncoordinated movement (ataxia)
- Muscle tremors
- Seizures
- Heart arrhythmias
Acute Toxicity (Overdose)
Toxicosis from local anesthetics is more likely to occur after accidental administration into a blood vessel. It typically affects the heart, causing cardiac arrhythmias and potentially cardiac arrest. It can also lead to hypotension (low blood pressure), which can cause collapse. [3]
Treatments for local anesthetic overdoses may include: [3]
- Supplemental oxygen
- Medications to reduce seizure activity
- Fluid therapy
- Drugs to increase blood pressure
Drug Interactions
Drug interactions after subcutaneous or topical local anesthetic use are unlikely, as the drug is not administered systemically (to the whole body). [3] During subcutaneous injection, the drug may rarely enter the bloodstream if the needle enters a vessel during administration. In these cases, drug interactions may occur.
The type of complication depends on what drug the local anesthetic is interacting with. Expected interactions include: [3]
- Alpha-2 adrenergic agonists: Drugs like dexmedetomidine or xylazine may increase the risk of ataxia.
- Antiarrhythmic medications: Examples include propranolol or quinidine, which may increase the risk of hypotension or arrhythmias.
- Cimetidine: May increase the effect of lidocaine.
- Ketamine: May increase the risk of ataxia.
Regulatory Status & Legal Considerations
There are numerous equine-labelled formulations of lidocaine approved by Health Canada and the FDA. [4][5] Mepivacaine also has an equine-approved formulation available. [4][5] Veterinarians can use these products on-label, or in a way that the drug company has tested and approved.
For ropivacaine and bupivacaine, veterinarians use human formulations in an off-label manner. This means the drug company has not tested the drug for use in horses. Veterinarians can still safely use the medication based on their previous experience and scientific research.
However, the drug company may not warrant the medication if there are adverse reactions or side effects, as they have not confirmed its safety for this use through their own testing.
Status in Competition
For most equestrian governing bodies, local anesthetics such as lidocaine are regulated because they can reduce pain sensation and potentially mask lameness or injury. The use of lidocaine and similar agents is generally prohibited in competition when administered in a manner that could affect performance, welfare assessments, or veterinary inspections.
However, these medications may be permitted for legitimate therapeutic purposes outside of competition, provided appropriate withdrawal times are observed.
Detection times and regulations vary among organizations, including the Fédération Équestre Internationale (FEI), national federations, and racing authorities, each of which maintains its own prohibited substances lists and medication control programs.
Horse owners should consult current competition rules and medication guidelines before administration of local anesthetics to horses that may compete. This helps ensure compliance with anti-doping regulations while protecting horse welfare and maintaining fair competition.
Frequently Asked Questions
Here are some frequently asked questions about local anesthetics in horses:
Local anesthetics in horses are medications that temporarily block pain and sensation in a specific area of the body. They work without causing unconsciousness, so the horse remains awake and responsive while the treated area is numbed. Veterinarians use local anesthetics for procedures such as wound repair, dental work, minor surgery, lameness exams, nerve blocks, joint blocks, and eye procedures.
Local anesthetics work in horses by blocking nerve signal transmission near the treated area. They bind to sodium channels in nerve cells, preventing the electrical signals that carry pain, touch, or temperature information from traveling to the brain. Sensory fibers are usually numbed first, while motor fibers may also be affected with additional time or higher volumes of anesthetic. [1][2]
The most common local anesthetics used in horses include lidocaine, mepivacaine, bupivacaine, and ropivacaine. Lidocaine and mepivacaine are often used when rapid onset is important, such as for nerve blocks, tissue infiltration, epidurals, and diagnostic lameness work. Bupivacaine and ropivacaine are longer-acting options that may be selected when extended pain control is needed, such as after surgery. [2][3]
The difference between local anesthesia and general anesthesia in horses is that local anesthesia numbs a specific area, while general anesthesia makes the horse unconscious. Local anesthetics block sensation in the targeted region without affecting the horse's awareness. Depending on the procedure, they may be used alone or with sedation, restraint, anti-inflammatory medications, or other pain management strategies.
Local anesthetics are used during lameness exams to help veterinarians identify where pain is coming from. By numbing a specific nerve, joint, or region of the limb, the veterinarian can observe whether the horse's movement improves. If lameness improves after a block, that result helps narrow the source of pain to the numbed area. Mepivacaine is commonly used in diagnostic lameness work because it has a relatively rapid onset and intermediate duration of action.
How long local anesthetics last in horses depends on the drug used, the injection site, the dose, and the individual horse. Lidocaine typically has an onset of 5 to 10 minutes and lasts about 60 to 90 minutes. Mepivacaine also takes about 5 to 10 minutes to work and lasts about 120 to 180 minutes. Bupivacaine and ropivacaine take longer to act, usually 10 to 30 minutes, but may provide numbing for 240 to 480 minutes. [2]
A veterinarian chooses between lidocaine, mepivacaine, bupivacaine, and other local anesthetics based on the procedure and the desired duration of numbing. Lidocaine is useful when rapid onset is needed and prolonged numbness is not required. Mepivacaine is often used for diagnostic nerve and joint blocks because it works quickly and lasts long enough for lameness evaluation. Bupivacaine or ropivacaine may be selected when longer-lasting pain relief is needed, especially around surgical procedures.
Local anesthetics are given to horses by several routes, depending on the procedure. Veterinarians may inject them under the skin, around a nerve, into a joint, or as an epidural around the spinal cord. They may also use topical forms such as creams, ointments, gels, sprays, patches, or ophthalmic preparations for the eye. Injectable forms are typically sterile liquid solutions. [1][2][3]
Local anesthetics can be used in a horse's eye when the product is specifically designed for ophthalmic use. Topical eye preparations may help reduce pain or allow easier examination and treatment of the eye surface. Skin ointments, creams, or other non-ophthalmic products should not be applied to the eyeball. Eye pain or eye injury in a horse should be assessed promptly by a veterinarian.
Local anesthetics are generally safe for horses when they are administered correctly by a veterinarian. Because they are usually applied locally rather than systemically, the risk of side effects is low. Problems are more likely if an excessive dose is used or if the medication accidentally enters a blood vessel. Dose, injection site, tissue health, proximity to blood vessels, and the horse's medical status all influence safe use.
Local anesthetics for horses should only be administered by or under the direction of a licensed veterinarian. These medications are prescription-only and require careful drug selection, dose calculation, and injection technique. Incorrect dosing or accidental injection into a blood vessel can cause serious adverse effects. Horse owners should follow veterinary instructions and never adjust medication use without professional direction.
Side effects of local anesthetics in horses are uncommon when the drugs are used properly. If the medication enters the bloodstream, possible effects include lethargy, drowsiness, uncoordinated movement, muscle tremors, seizures, and heart arrhythmias. Horses with liver disease, kidney disease, heart disease, or existing arrhythmias may require extra caution if systemic exposure occurs. [3]
Signs of local anesthetic toxicity in horses can include lethargy, ataxia, muscle tremors, seizures, abnormal heart rhythms, low blood pressure, collapse, or cardiac arrest. Toxicity is more likely when a local anesthetic is accidentally injected into a blood vessel or when the total dose becomes too high. This is an emergency that requires immediate veterinary attention. Treatment may include oxygen, seizure-control medications, fluid therapy, and drugs to support blood pressure.
Local anesthetics can interact with other medications if enough of the drug enters the bloodstream, although interactions are unlikely after proper topical or subcutaneous use. Alpha-2 adrenergic agonists such as xylazine or dexmedetomidine, ketamine, antiarrhythmic drugs, and cimetidine may increase the risk or severity of certain side effects. Horse owners should tell their veterinarian about all medications and supplements the horse has received before any procedure.
Local anesthetics are regulated in competition horses because they can reduce pain sensation and potentially mask lameness or injury. Use of lidocaine and similar drugs is generally prohibited in competition when administration could affect performance, veterinary inspection, or welfare assessment. These medications may be permitted for legitimate therapeutic use outside competition if appropriate withdrawal times are followed. Rules vary between organizations, so owners should check current FEI, national federation, or racing authority medication guidelines before competing.
Local anesthetic injections may cause brief discomfort when the needle is placed or when fluid is injected into the tissue. This discomfort is usually short-lived, and the treated area becomes numb once the medication takes effect. Veterinarians may use careful handling, sedation, or appropriate restraint to help keep the horse calm and safe during the procedure.
Some horses need sedation for procedures involving local anesthetics, but sedation and local anesthesia are not the same thing. Sedation helps the horse stay calm and still, while the local anesthetic blocks pain or sensation in a specific area. Whether sedation is needed depends on the procedure, the horse's temperament, the location being treated, and safety considerations for the horse and handlers.
A horse may not move normally after a nerve block because sensation, proprioception, or pain perception may be temporarily altered. This is why horses should be handled carefully after local anesthesia and should not be ridden, worked hard, or turned out unsupervised unless a veterinarian says it is safe. Numbing a painful area can also make a horse appear more comfortable than it truly is, increasing the risk of overuse if activity is not controlled.
Yes, local anesthetics can temporarily mask pain from an injury by blocking nerve signals from the affected area. This effect is useful during diagnostic lameness exams because it helps veterinarians identify the source of pain. However, it also means the horse may not protect the injured area normally while the block is active. Horses should not be exercised beyond the veterinarian's instructions after receiving a local anesthetic.
Veterinarians wait after giving a nerve block because local anesthetics need time to take effect. The waiting period depends on the drug used, the location of the block, and the structures being numbed. After the anesthetic has had time to work, the veterinarian reassesses the horse's movement to determine whether the block improved the lameness or changed the horse's response to pain.
Yes, local anesthetics can spread beyond the exact injection site, especially when larger volumes are used or when the medication diffuses through nearby tissues. This can affect diagnostic accuracy during lameness exams because improvement may reflect numbing of a broader region than intended. Veterinarians choose injection sites, volumes, and reassessment timing carefully to reduce the chance of misleading results.
Yes, nerve blocks can sometimes give unclear or misleading results. A false or incomplete result may occur if the anesthetic does not fully numb the intended area, spreads to nearby structures, or if the horse has more than one source of pain. Changes in footing, excitement, sedation, or inconsistent movement can also affect interpretation. For this reason, nerve blocks are interpreted alongside the full lameness exam and other diagnostic findings.
How long a horse should rest after receiving a local anesthetic depends on why the medication was used, which area was numbed, and whether an injury or procedure was involved. After diagnostic nerve or joint blocks, veterinarians typically recommend controlled handling until normal sensation returns. After surgery, dental work, or wound treatment, activity restrictions depend on the underlying condition and the veterinarian's treatment plan.
Local anesthetics are a type of pain-control medication, but they are not the same as systemic painkillers such as non-steroidal anti-inflammatory drugs. Local anesthetics block nerve signals in a specific region for a limited time. Other pain medications may reduce inflammation, alter pain perception, or provide broader whole-body pain relief. Veterinarians may use more than one type of pain management depending on the procedure and the horse's condition.
Yes, local anesthetics can be used during equine dental procedures when specific areas of the mouth need to be numbed. Dental nerve blocks may be used for procedures such as tooth extraction, treatment of painful oral disease, or other interventions involving the teeth and surrounding tissues. These blocks are often combined with sedation so the horse remains calm, still, and more comfortable during treatment.
Summary
Local anesthetics are prescription medications used in horses to numb specific tissues, reduce pain, and support diagnostic or therapeutic procedures without causing unconsciousness. Veterinarians select the appropriate drug and route based on the procedure, desired duration, safety considerations, and competition rules.
- Local anesthetics block nerve signaling so pain and sensation do not travel normally from the treated area
- Lidocaine and mepivacaine are commonly used when rapid onset is needed for procedures or lameness diagnostics
- Bupivacaine and ropivacaine provide longer-lasting numbing and may be used when extended pain relief is required
- These medications may be applied topically or administered by injection for nerve blocks, joint blocks, epidurals, or tissue infiltration
- Side effects are uncommon when local anesthetics are used correctly, but overdose or accidental bloodstream exposure can cause serious reactions
- Competition horses require careful attention to current medication rules, detection times, and withdrawal guidelines
References
- Garmon. E. H. et al. Topical, Local, and Regional Anesthesia and Anesthetics. StatPearls. StatPearls Publishing, Treasure Island (FL). 2026.
- Doherty. T. et al. Eds. Manual of Equine Anesthesia and Analgesia. 1st ed. Wiley. 2022.
- Plumb. D. C. Veterinary Drug Handbook. Pocket 7. ed. Wiley Blackwell, Ames, Iowas. 2011.
- Drug Product Database. Health Canada.
- Animal Drugs @ FDA. Food and Drug Administration.
