Are Tick Bites Dangerous for Horses? Complete Guide to Equine Tick-Borne Disease & Prevention

Ticks are small arachnids that feed on the blood of horses, humans, and many other animals. They pose a significant health risk because they can transmit harmful pathogens such as bacteria, viruses, and protozoa. ^[1][2]

Ticks are commonly found in wooded areas, grassy fields, and places where horses graze. When ticks bite, they can transmit serious diseases to horses, including Lyme disease, anaplasmosis, and piroplasmosis. ^[1][2]

Early detection and effective management of tick bites are essential for maintaining horse health. Regularly inspecting horses, particularly during high tick activity seasons, can help identify and remove ticks before they transmit diseases. ^[3]

Additionally, using external acaricidal parasite control products along with regular grooming can significantly reduce tick infestations and the risk of disease. ^[3]

Horse owners and caretakers need to know how to properly identify and remove ticks, as many common removal methods can actually increase the risk of disease transmission. Read on to learn everything you need to know about tick-borne disease in horses to be equipped to protect your herd from these blood-sucking pests.

Tick Bites and Horses

Ticks are small, parasitic arachnids that are adapted to variety of hosts, including humans, dogs, birds, reptiles, and horses. Ticks pose several risks to horses, including the transmission of dangerous diseases, skin irritation, and other health complications.

After attaching to a host, ticks use their specialized mouthparts to feed on the host’s blood, a process that can last from several hours to days.

Ticks typically range from 1 to 10 millimeters in length, depending on their species and feeding status. ^[4] Unfed ticks are usually quite small, but they become significantly larger when engorged with blood after biting a horse or other host.

Ticks have a flat, oval, or teardrop-shaped body that becomes more rounded when engorged. Their color varies and different species may be brown, black, red or gray.

Ticks are found worldwide, inhabiting a variety of environments across every continent. They thrive in temperate regions with warm, humid climates, which are ideal for their development and survival. ^[3]

Tick Habitats

Ticks are typically found in environments that provide ample opportunities to come into contact with potential hosts. They thrive in areas with dense vegetation, such as: ^[5][6]

• Grassy fields
• Forests
• Woodlands
• Shrublands

Horses commonly encounter ticks along trails, in tall grasses, and at the edges of wooded areas. Ticks can detect a host’s presence and climb onto vegetation, where they reach out (referred to as “questing“) to latch on as the host passes by. ^[7][8]

In North America, ticks are common throughout the United States, Canada, and Mexico, where they are most active from spring through fall. ^[5] However, with shifting conditions related to climate change, veterinarians currently consider ticks a year-round concern in North America, especially in southern areas where winters are mild.

Life Cycle of Ticks

Understanding the tick life cycle is fundamental to effective management and prevention of tick-borne diseases. Each stage of the cycle involves specific behaviors and transitions that impact how ticks spread pathogens. ^[3][4]

There is some variance in tick life cycles depending on the species.

One-host life cycle

Ticks with a one-host life cycle remain on the same host throughout their entire development. They attach as larvae, feed, molt into nymphs, and continue to develop into adults, all while staying on the same host. The cycle is completed when the adult female detaches to lay eggs. ^[9]

This type of life cycle is observed in species like the Brown Dog Tick (Rhipicephalus sanguineus) and is typically completed within 4 to 8 weeks. ^[3][9]

Two-host life cycle

In this type of life cycle, ticks begin as larvae on one host, where they feed and molt into nymphs. After this stage, they detach and move to a second host, where they complete their development into adults and lay eggs. Only a small number of tick species have a two-host life cycle. ^[9]

Three-host life cycle

Ticks with a three-host life cycle use different hosts for each developmental stage. The cycle begins with adult females laying eggs, which hatch into larvae that feed on a small host, such as a bird. The larvae then molt into nymphs, which feed on another host, often a slightly larger animal.

Nymphs mature into adults on a third host, where they feed on larger mammals, like horses and deer, and lay eggs, completing the cycle. ^[4][3]

This life cycle is common in species such as the black-legged or deer tick (Ixodes scapularis) and typically lasts between 1 to 3 years, depending on environmental conditions and the tick species. ^[9][10]

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Health Risks of Tick Bites

Ticks pose a significant health risk to horses and other host animals, including humans, due to their ability to transmit a variety of pathogens. These pathogens can cause serious diseases ranging from mild symptoms to severe, life-threatening conditions. ^[11]

Ticks often feed for several days, which increases the likelihood of pathogen transmission and allows them to inject more toxins into their hosts. Their wide host range, encompassing mammals, birds, and reptiles, further facilitates the spread of diseases across different species.

Additionally, some tick species have developed resistance to acaricides, which are chemicals designed to kill or control arachnids, due to their repeated use. While these treatments effectively kill susceptible ticks, the resistant ones survive and reproduce, making control efforts more challenging. ^[12]

It’s important to discuss any concerns about ticks with your veterinarian, as they are familiar with the most effective treatments for local tick populations.

Beyond the risk of disease transmission, tick bites can also cause localized irritation, itching, and discomfort, and may lead to secondary bacterial infections if not managed properly.

Equine Tick-Borne Diseases

Tick-borne diseases refer to infectious conditions transmitted by ticks to their hosts. There are also some species of ticks that transmit a neurotoxin (rather than an infectious pathogen) associated with tick paralysis.

In horses, tick-borne diseases can cause a wide range of symptoms, from mild discomfort to severe, life-threatening conditions. ^[2][11]

While many tick-borne diseases have been identified across multiple host species, the ones most relevant to horses are:

• Anaplasmosis
• Lyme Disease
• Piroplasmosis (also known as babesiosis)
• Tick paralysis

Anaplasmosis

Anaplasmosis is a bacterial infection caused by Anaplasma phagocytophilum, which is primarily transmitted by ticks. This disease impacts the horse’s blood cells, leading to a variety of clinical signs. ^[13]

The bacteria infect and replicate within white blood cells, which can result in fever, lethargy, loss of appetite, and anemia. Horses may also show signs such as swollen limbs, joint pain, and increased respiratory effort. In severe cases, the infection can cause respiratory distress and potential organ failure. ^[14]

Ticks known to transmit anaplasmosis include the black-legged tick (Ixodes scapularis), also known as the deer tick, and the Western black-legged tick (Ixodes pacificus). Early diagnosis and treatment with antibiotics are the most effective course for managing the disease and improving outcomes for affected horses. ^[3]

Lyme Disease

Lyme disease in horses is caused by the bacterium Borrelia burgdorferi, which is transmitted primarily through the bite of infected ticks. The black-legged tick (Ixodes scapularis) and the Western black-legged tick (Ixodes pacificus) are the primary vectors of this disease. ^[15]

Lyme disease can lead to a range of clinical symptoms as the bacterium affects various systems within the horse’s body. Affected horses may exhibit signs such as fever, lethargy, and loss of appetite. They might also show more specific symptoms like lameness, which can be intermittent or shifting, joint swelling, and stiffness. ^[16]

Other potential signs of Lyme disease in horses include skin sensitivity, behavioral changes, and, in severe cases, neurological symptoms such as incoordination.

Equine Piroplasmosis (EP)

Equine piroplasmosis (EP) is a serious parasitic disease in horses caused by protozoan parasites of the genus Babesia, specifically Babesia caballi and Theileria equi. ^[17]

These parasites are transmitted primarily by ticks, with the primary vectors being the Southern cattle tick (Rhipicephalus microplus) and the Tropical horse tick (Dermacentor nitens). ^[3]

Once transmitted, the parasites invade and destroy red blood cells, leading to a range of clinical signs. ^[3]

Horses with piroplasmosis may exhibit fever, jaundice (yellowing of the skin and mucous membranes), and lethargy. They may also show signs of colic, swelling in the limbs, and in severe cases, respiratory distress and potential organ failure.

The disease can progress rapidly and, if not treated promptly, can be fatal. Early detection and treatment are critical to managing piroplasmosis and preventing severe outcomes.

Tick Paralysis (TP)

Tick paralysis (TP) is a rare but serious condition in horses caused by neurotoxins in the saliva of certain tick species. These toxins disrupt the horse’s nervous system, leading to progressive paralysis that can become life-threatening if not treated promptly.

The condition is most commonly associated with the feeding of female ticks, particularly species like Ixodes holocyclus (found in Australia) and potentially Dermacentor variabilis (in North America). After 3 days of attachment, the female tick starts injecting detectable amounts of toxin, with peak levels on days 5 and 6. ^[18][19][20]

Tick paralysis initially presents with hindquarter weakness and a wobbly gait. As the condition progresses, paralysis can spread to all four limbs and the neck, leading to recumbency, where the horse is unable to stand. ^[19]

In severe cases, the paralysis can affect the muscles controlling breathing, resulting in respiratory distress. Horses may also show signs of anxiety, difficulty swallowing, or changes in vocalization as the paralysis advances. Without prompt intervention, this condition can lead to sudden death.

Signs & Symptoms

The definitive sign of a tick bite on a horse is the presence of the tick itself attached to the horse’s skin. Ticks that have been attached for a short time appear flat, while those that have been feeding for several hours or days become rounded due to blood consumption. ^[2]

In some cases, after the tick drops off, horse owners and caretakers might notice skin damage where the tick was attached. A scabby area or sore may be observed, potentially containing pus or crust. This localized irritation is a direct response to the tick’s bite and can be accompanied by redness and swelling around the site.

Horses may also show signs of itching and discomfort, such as scratching or rubbing the affected area. The bite site might become sensitive or painful, causing the horse to react when touched. Persistent irritation can lead to hair loss around the bite area.

How to Remove a Tick from a Horse

Removing a tick from a horse requires careful handling to minimize discomfort and reduce the risk of disease transmission. Once the horse is secure, locate the tick and part the horse’s hair to clearly expose the attachment site.

Using tweezers, needle-nose pliers, or a tick removal tool, grasp the tick as close to the skin as possible, being careful not to squeeze the tick’s body to avoid releasing harmful bacteria or toxins. Pull the tick straight out with steady, even pressure. Do not twist or jerk, as this can squeeze the tick’s innards into the bite wound, potentially transmitting any pathogens or toxins that may be present. ^[2][8][3]

Keep pulling the tick outwards until it releases the horse’s skin. If it seems stuck, continue pulling gently; it will eventually let go.

After successfully removing the tick, place it in a container for disposal. Some people elect to wrap excised ticks with sticky tape to ensure they do not re-attach to other animals after removal. Avoid crushing the tick with your fingers and wash your hands thoroughly after handling ticks.

Medications for Tick Bites

Horses infested with ticks may require treatment with an acaricide specifically designed to kill attached tick larvae, nymphs, and adults. ^[3] These drugs work by targeting the nervous system of the ticks, leading to their death.

Acaricides are available in various forms, such as sprays, spot-on treatments, or powders. It’s important to choose a product that is safe for horses, as not all acaricides suitable for other animals are appropriate for equine use.

Only select tick control products specifically formulated for horses, as they have been tested and approved for safety. Avoid using products designed for other species, as they can contain ingredients that may be harmful or less effective when used on horses.

The effectiveness of tick control products can vary depending on the species of tick and the environment. Consult your veterinarian when choosing parasite control medications, including horses. Your veterinarian can provide a prescription or recommend the most suitable product for your horse.

Prevention

Effective prevention of tick-borne illnesses in horses involves a combination of routine body checks and targeted external parasite control. Regularly inspecting your horses for ticks and using appropriate acaricides can significantly lower the risk of tick-borne diseases.

Understanding tick behavior and consistently applying these strategies help protect your herd from harmful infections.

Routine Body Checks

Different tick species prefer specific attachment sites on horses based on their biology and feeding habits. Knowing these preferences is key for thorough tick checks and effective treatment application to prevent tick-borne diseases. ^[21]

Regular body checks are a cornerstone of preventing complications due to tick bites. By routinely examining your horse, you can detect and remove ticks before they transmit diseases.

Key areas to inspect regularly on your horse’s body include: ^[2][3]

• Inside and around the ears
• Around the eyes and muzzle
• Under the jaw and along the neckline
• At the base of the mane and underneath the tail (near the tailhead)
• Typical hiding spots such as between the front legs, behind the elbows, and along the belly
• Pasterns and fetlocks (lower legs)

External Parasite Control

Incorporating acaricides into your tick prevention strategy is as important as physical control of the horse’s environment and body. These products are designed to control and repel ticks at various stages of their life cycle, helping to protect your horse from disease.

Options for parasite control include: ^[3]

• Topical Acaricides: Applied directly to the horse’s skin, typically as a liquid or gel. Pour-on acaricides are spread along the horse’s back for broad coverage, while spot-on acaricides are applied to specific areas for targeted protection.
• Spray and Powder Acaricides: These products are typically used to cover larger areas of the horse’s body. They work by either repelling or killing ticks upon contact and can be beneficial for managing infestations in areas with high tick activity.
• Systemic Acaricides: Administered orally, systemic acaricides like ivermectin work from within the horse’s body to provide internal protection. These acaricides are absorbed into the bloodstream and are effective against ticks that feed on the horse.
• Environmental Acaricides: These compounds are used to target ticks in the horse’s environment, such as stables, pastures, and bedding areas. Environmental acaricides help to reduce the overall tick population and lower the risk of tick re-infestation.

For oral acaricides to be effective, ticks must first feed on the treated horse to ingest the drug, which may not prevent disease transmission if ticks can spread diseases shortly after starting to feed. ^[22]

Products containing pyrethrin, permethrin, cypermethrin, or other pyrethroids can be applied in and around barns, pastures, and paddocks to reduce tick exposure in the environment. Always follow the product directions carefully to ensure safe and effective use.

Consider working with a qualified pest control professional if you are unsure what the best course of environmental control is for your operation.

Some owners choose natural tick repellents, such as those containing essential oils like eucalyptus, peppermint or citronella. While these can offer some protection, they are generally less effective than chemical insecticides, tend to provide more variable results, and may need more frequent reapplication. ^[23][24]

In addition, many essential oils are not safe for oral or topical use. Unregulated natural insect control products may not be subjected to robust quality control, so their ingredients can vary in composition and quality. Check with your veterinarian before using any type of insect control on your horse.

Environmental Management

Effective habitat modification can also help manage tick populations. Regular maintenance of pastures and paddocks can significantly reduce tick presence. Mowing the grass frequently helps keep it short, which limits the habitat available for ticks. ^[26][27]

Additionally, clearing brush, removing tall vegetation, and eliminating leaf litter around the horse’s living areas help eliminate potential hiding spots and breeding grounds for ticks.

Installing fencing around horse living areas further aids in tick management by keeping wildlife, such as deer and rodents, away. These animals can carry ticks into the environment, so restricting their access to horse pastures helps control tick populations more effectively.

Summary

Ticks are small arachnids that feed on blood and pose significant health risks to horses by transmitting pathogens that can cause serious diseases.

• Early detection and removal of ticks through regular body checks are crucial. Focus on areas such as around the ears, eyes, muzzle, and under the tail.
• Use tweezers or a tick removal tool to carefully grasp and pull ticks out to avoid leaving mouthparts behind and minimize infection risk. Avoid burning or smothering attached ticks.
• Effective tick prevention involves a combination of environmental management, regular tick checks, and the use of acaricides in various forms—topical, spray, powder, systemic, and environmental treatments.