THE MOST COMMON HOOF CRACKS
These tiny parasites feed on your horse’s blood and can pass along several pathogens as they do. Here’s what you need to know to protect your horse from ticks.
You’ll hear many terms for hoof cracks---sand cracks, weather cracks, grass cracks, etc.---but the most basic way to describe these defects is according to their location and direction. These indicators also offer clues to the origin and severity of the problem.
Vertical cracks, which run perpendicular to the ground, are the most common. The reason has to do with the anatomy of the hoof wall itself. Like human fingernails, hoof wall is composed mainly of a protein called keratin, which forms tubules---structures that look like densely packed drinking straws. These tubules run vertically down the hoof, from the coronary band to the ground, and give the hoof much of its structural strength, like the rebar in concrete. Weaknesses that allow cracks to form are much more likely to develop between the parallel tubules than across them.
Location determines how serious these cracks are likely to be. Those that originate at the bottom edge of the hoof wall and climb upward are typically just a cosmetic concern that is likely to be eliminated at the next trimming. Vertical cracks that originate at the coronary band and grow downward are more worrisome, especially if they’re deep, because disruption at the coronary band affects the production of new, healthy horn.
Vertical cracks are further defined by where they appear on the hoof wall:
• Toe cracks occur in the front third of the hoof. Because the hoof wall is thickest and strongest at the front of the hoof, serious cracks at the toe are less likely to be caused by external injuries. However, abscesses, bruises and other internal issues that loosen the bond between the hoof wall and the underlying connective tissues can create weakness in the structure that may result in a deep crack.
Chronic toe cracks can also occur in horses with conformation issues that increase stresses on the front of the hoof. “Abnormally high or low coffin bone angles cause toe cracks,” says Steve Kraus, BS, CJF, head farrier of the Cornell University College of Veterinary Medicine. “Often, long pasterns and low-angled heels cause the front of the hoof to extend too far ahead of the leg.” As the horse walks, the breakover places extreme leverage on the inside of the hoof wall, which can bend the wall inward and cause cracks.
“When a hoof has an
abnormally high coffin bone angle, the hoof will land toe first, which also puts excessive force on the inner hoof wall, creating the crack,” says Kraus.
• Quarter cracks develop along the side of the hoof; these tend to cause more trouble than toe cracks because the wall is thinner and must flex as the hoof bears weight. Any cracks in the side of the hoof will be less stable and are more likely to lead to lameness.
Quarter cracks are often caused by conformation defects in the legs, such as legs that toe out. “When the hoof is out of balance it creates too much pressure on one side of the capsule,” says Tommy Boudreau, a farrier in Mineral Wells, Texas. “This will push into the coronary band and cause it to jam up. With all the extra pressure in one spot on that side of the foot it can make it break out and crack.”
These conformation faults tend to create chronic cracks in a predicable location, says Kraus: “If you drop a plumb line down from the front of the horse’s shoulder, it will point to the crack.”
An underrun heel and long toe also places stresses on the quarters with each step. The prying forces will separate the hoof wall at the bottom first, and the crack will grow upward. Its edges will spread apart as the horse bears weight.
• Heel cracks occur at the rear of the hoof, below the heel bulbs. Like quarter cracks, these, too, are likely to cause lameness. A shoe that shifts to the side or is too small to support the entire heel to begin with is a common cause of a heel crack. The portion of the heel that overhangs the end of the shoe may split vertically; the edges of the crack will slide up and down past each other with each step.
Overstrikes, when a horse hits the coronary band of a front foot while overreaching from behind, are another common cause of both heel and quarter cracks. “A blow to the coronary band causes a bruise and damage to those tissues,” says Boudreau. “If there’s not enough blood supply in the damaged area that took the blow, this can cause a quarter crack. If the horse overreaches and hits the coronary band, it is usually somewhere in the area between the region of the heel nail and the buttress--the back part of the foot.”
TRIAGE FOR CRACKED HOOVES
When you notice a crack you’d never seen before, you need to make a decision: Do I need to call a farrier right away? Or can this wait until our next scheduled visit? You’ll need to get a close look at it.
In general, the severity of a crack depends upon its depth. Even if they’re long, cracks that are limited to the outer layers of the hoof wall are usually not serious. Most will grow out with the wall and eventually be trimmed off with no harm to the horse. It is, however, a good idea to keep an eye on these blemishes to make sure they do not develop into more significant injuries.
The cracks to worry about extend deeper into the hoof wall---enough to weaken it. Call your farrier right away if you discover a hoof crack with any of these signs:
• Instability of the hoof wall. Watch as a friend walks your horse a few steps on hard, level ground. Does the hoof wall shift as the horse places his weight on it? If you pick up the hoof and handle it gently, you may be able to feel the instability on each side of the crack.
• Draining fluids. Any blood or pus that appears around the edges of the crack may indicate that the fissure has penetrated all the way to
the interior of the hoof.
• Pain or lameness. Any soreness or unsoundness, however minor, is worth investigating.
• Involvement of the coronary band. Any injury at the coronary band can affect the growth of future hoof wall.
Moshier says he runs into many people who are unsure whether to call the farrier between regular visits to look at a crack. “My answer is that they should call the farrier when the horse is lame as a result of the crack,” he says. If they’re still in doubt, he adds, “I ask my owners to take pictures of the feet with their phone, so they can send a photo to me to ask if it’s something they need to worry about.”
TREATMENT OPTIONS
The basic approach to managing any hoof crack, no matter how serious, is to stabilize the hoof and keep the horse comfortable while new horn grows in and the damaged section is trimmed away---this can take up to a year for cracks that started at the top of the hoof. “Trauma to the hoof, such as an abscess, seldom requires more than good regular trimming and in some cases a properly fitted shoe,” says Heather O’Brien, a farrier from
British Columbia.
Bar shoes are often used to help support cracked hooves. “In most cases the farrier will put clips on the shoe---on each side of the crack---to help prevent movement,” says Moshier.
“It depends on the case.”
Not all cracks spread apart when weighted---some toe cracks roll inward and “overlap” when the horse puts weight on the foot. “While people tend to think that we need to stabilize that crack by keeping it together, some types of crack repair involve keeping the edges of the crack apart, so they don’t roll inward,” he adds. “Clips, in this case, won’t do much good.”
More extensive measures may be needed to manage unstable cracks. “Lacing,” for example, involves binding the two sides of the crack together using various materials and techniques, including metal plates or steel wires. “If there is a lot of movement in the crack, we might have to lace it together,” says Moshier. “This can be done by putting horseshoe nails across the crack to hold it together or lacing with stainless steel threads.”
Another option is to use acrylic or polyurethane products to repair cracks and replace lost hoof wall. In more severe cases, the patches may be reinforced with fiberglass. “These stabilize the crack ---essentially gluing it to keep the edges stable so they won’t be moving as the crack grows out,” explains Moshier.
The patch material will then be trimmed away as the hoof wall grows out. “If you apply the patch properly, you can just keep trimming the patch just like the hoof wall as it grows down,” says Boudreau. “If everything works the way it is supposed to, it will grow right on off and then you’ll have a strong, healthy foot again.”
For the most serious cases, when a horse is significantly lame and his long-term soundness is at risk, the farrier will need to work in conjunction with a veterinarian, who can prescribe medications to relieve pain and control infections. In some cases, dead or dying tissue may need to be removed, and x-rays may be
needed to look for the position and potential injuries to the coffin bone and other structures within the foot.
Even as the work to stabilize the hoof is under way, it is important to adjust trimming and shoeing to address any hoof imbalances or other stressors that caused the crack in the first place. “The one thing consistent in all successful recoveries from a crack is the proper balancing of the foot to the horse’s conformation,” says O’Brien. “Without this, the crack will keep returning until proper balance is restored.”
PREVENTIVE MEASURES
Simply keeping your horse healthy---with balanced nutrition, not overweight, and plenty of turnout and exercise in good footing---will go a long way toward keeping his hooves strong as well. Beyond that, you can take additional steps to reduce the risk of hoof cracks:
• Stay on schedule with your farrier. Whether the horse is barefoot or shod, regular visits from your farrier are important to keep his feet properly trimmed and balanced in accordance with his conformation. Flares that form at the bottom of overgrown hooves can easily form cracks. “When the hoof wall gets too long it will bend, then crack,” says O’Brien. “Debris from the environment can become
embedded in the crack, especially if the horse is barefoot, causing abscesses and even white-line disease.”
• Use traction aids only when needed. Calks, rims, borium and other traction devices may be invaluable if you often ride on slick surfaces, but they can add stresses to the hooves and legs that can lead to cracks. Your farrier can advise you on the most appropriate shoes for the type of riding that you do.
• Add a supplement, if
necessary. A horse whose diet is deficient in important vitamins and trace minerals is likely to have weak, shelly hooves as well as dull, coarse hair. Biotin is the primary ingredient in supplements intended to improve hoof health; many also contain minerals such as copper and zinc as well as amino acids and omega-3 and -6 fatty acids. If you suspect your horse may benefit from a hoof supplement, consult with your veterinarian or an equine nutritionist to assess his diet and create a healthier overall ration.
• Stop the stomping. Horses harassed by stable flies in the summer will stomp their feet repeatedly--which can lead to hoof cracks if they’re on hard, dry ground. Fly sprays will repel stable flies, and a number of management strategies can help keep insect populations under control. These flies breed in decaying organic matter, so clean up soiled bedding and manure from turnout areas daily, and treat the manure pile with insecticides or larvicides. If flies remain a problem, consider outfitting your horse with fly boots, which cover the legs and prevent the pests from landing on your horse.
• Keep an eye on footing. Galloping over hard ground poses an obvious risk of cracks, but deep, soft footing also places stresses on the hoof that can cause injury to the hoof wall. Out on the trail, slow to a walk when you encounter ground that is either deep and soft or hard and rocky, and drag your arena frequently to keep the footing uniform.
• Avoid the wet/dry cycle. When hooves get wet, they soften and swell; when they’re dry, they stiffen and contract. Horses can adapt to either condition, but alternating between the two on a daily basis can loosen shoes and cause cracks.
“It’s not just the horse that’s constantly standing in mud, or a horse that lives in a dry desert environment,” says Moshier. “The biggest problems occur when horses are always alternating, such as going from a stall bedded in kiln-dried shavings to being turned out in the muck or wet pastures.” If your turnouts are chronically muddy, look for ways to improve drainage. Laying gravel in high-traffic areas may also help.
• Inspect your horse’s hooves daily. Picking out the hooves is an essential part of good horsemanship, but as you do this chore, take some time to inspect the overall health of the hoof: Run your hand over the hoof wall and coronary band to feel for defects. Look for dark spots on the sole, which could indicate bruising. Wiggle the shoe to check for looseness---if you have a farriery tool called clinchers on hand, you can tighten the clinches. If the shoe is on the verge of falling off, your safest option may be to remove it entirely. “I advise people, when cleaning the feet, to pick the white line and clear everything out of it. That’s the area to look at closely,” says Moshier. “Look for any blackness in the white line because that’s a sign of infection.”
When it comes to hoof cracks, the best advice is simple: Get to know your horse’s hooves. Keep an eye on them and consider taking photographs occasionally: These can help you determine if a crack is new or if a preexisting defect is getting worse.
Keeping your horse’s hooves healthy and strong requires attentive care. But if you can prevent serious hoof cracks, you’ll give him a solid foundation for a lifetime.
Ticks are relentless, blood-feeding ectoparasites that infest almost every type of animal, including horses. With a resume like that you’d think we’d all be on high alert, all the time, to ensure ticks are identified and disposed of before they have the opportunity to attach to our horses. However, equine tick infestations can go undetected, even by conscientious owners, due to the horse’s thick hair coat and the tick’s small size. Couple that with a widespread misconception that ticks only feed in warmer months of the year or in certain habitats, and ticks persist as a particularly icky equine parasite.
But ticks are more than gross. They can cause skin irritation, secondary infections at bite wounds and even anemia. Most concerning, ticks can pass along pathogens, such as those that cause equine piroplasmosis and Lyme disease. As global climate trends have led to increasing tick populations and expanded distributions, these tiny arachnids are becoming an increasingly significant equine health concern. All of which makes it more important than ever to learn which tick species are most likely to bite your horse and the threats they pose when they do.
THE SEVEN TICK SPECIES OF GREATEST CONCERN
Although many species of ticks can infest horses, some are more common than others. Geography, landscape and time of year influence which types of ticks your horse is most likely to encounter (see “Geographic Distribution,” page 62). Be aware that even less-common species can cause significant health problems, so it’s important to still be on alert for them. Here’s a rundown of ticks that most commonly cause problems in horses.
1. Black-legged ticks or deer ticks (Ixodes scapularis and Ixodes pacificus). These small ticks are dark brown to black in color. Unlike many other North American ticks, black-legged ticks search for hosts (a behavior described as “questing” by entomologists) during the cooler months of the year. They tend to be found on woody understory---the lower level of vegetation---protruding from dense leaf litter in forested regions. They also rely on white-tailed deer to maintain their populations but will readily feed
on other medium or large mammals. Ixodes scapularis is the black-legged tick found in abundance in eastern North America while Ixodes pacificus is encountered west of the Rocky Mountains; both species readily infest horses.
2. Lone star ticks (Amblyomma americanum). This aggressive tick is found most often in wooded areas with ample leaf litter that preserves moisture. Adults may track potential horses using shadows or carbon dioxide from exhalations. These ticks are reddishbrown, and a female will have a white dot on its back while a male will have white markings along the edge of its body. All three stages (larvae, nymphs, and adults) may be found on horses, although identifying the tiny, immature larvae and nymphs requires close, careful examination. Historically, the distribution of this tick was concentrated in the southcentral and southeastern United States, but over the last decade, populations have extended their range to eastern and midwestern regions.
3. Gulf Coast ticks (Amblyomma maculatum). This ornately patterned and rather large tick thrives in open areas, coastal wetlands and grasslands. It feeds on a variety of hosts regardless of life stage and may be seen questing during the heat of the day when other ticks are taking refuge from the hot sun under leaf litter. As the name implies, this tick is found in regions neighboring the Gulf Coast, but populations have expanded and it can now be found as far north as Kansas in the Midwest and up the East Coast as far as Connecticut. This tick is a notoriously deep feeder, leading to significant skin trauma at the site of attachment. For example, Gulf Coast ticks can induce a condition called “gotch ear” in horses, mules, cattle and goats, where numerous ticks are attached to the inner and outer surface of the ear pinnae, resulting in severe inflammation and droopy ears.
4. Wood ticks (Dermacentor
variabilis and Dermacentor andersoni). Virtually identical in shape and markings to one another, wood ticks are brown with a white lacy pattern along the back. These ticks prefer grassy areas near forest boundaries and are often seen along edges of trails. Adults feed on medium to large mammals; a recent study found Dermacentor variabilis to be the second most common tick infesting horses in the summer. Considered together, wood ticks are found in every region of the United States, though Dermacentor variabilis (American dog tick) is more prevalent in the Northeast, South, Midwest and along the Pacific Coast, while Dermacentor andersoni is encountered solely in the Rocky Mountain states.
5. Winter ticks ( Dermacentor albipictus). Uniquely, this tick lives on a single host through all life stages (larva, nymph, adult). Larvae quest for a host in large groups in the cooler months of the year, and after feeding molt to the next life stage on the same host. Because they attach in large numbers and stay on the same host for the entire season, heavy infestations can cause anemia. Winter ticks survive in a variety of environments, including open and closed canopy forests. They primarily feed on wild ruminants such as moose, elk and deer, but are often found on cattle and horses.
This tick is widely distributed across North America. In its southern range, a solid brown variant (no pattern on the back) predominates. In other regions, adult winter ticks have a similar white, ornate pattern as the wood ticks.
6. Asian Longhorned ticks (Haemaphysalis longicornis). Newly introduced to North America, this reddishbrown tick has no markings and is found on a variety of hosts, including horses. Longhorned ticks thrive on long grasses in humid, warm conditions but can survive in a variety of climates. Though the distribution is currently concentrated in the eastern United States, where it was first recognized in 2017, this tick has been found as far west as Arkansas and the range is expected to continue expanding since this tick is adaptable to many climates and hosts. In addition, longhorned ticks are parthenogenic, meaning no males are needed for successful reproduction.
7. Spinose ear ticks (Otobius megnini). Only the immature stages (larva and nymph) of this tick feed on animals, including horses. They usually attach deep in the ear canal. Adults are freeliving in the environment and do not feed on blood. Referred to as a soft tick, based on the lack of a hard outer covering, spinose ear ticks are intensely irritating. An infested horse may frantically tilt his head or throw himself to the ground in response to the sensation of ticks feeding in the external ear canal. This tick is most common in the hot, dry environment of the southwestern United States and Mexico.
THE PATHOGENS THEY BRING
You may be aware of Lyme disease and equine granulocytic anaplasmosis ---both currently considered the most common tick-borne diseases affecting horses in the United States---but several other pathogens spread by these tiny parasites are also cause for concern. Here’s an overview of the tick-borne diseases most seen in horses:
• Lyme disease. One of the most well-known tick-borne diseases, Lyme disease is caused by the Borrelia burgdorferi organism, which is transmitted by black-legged ticks. In horses, Lyme disease may cause enlarged lymph nodes, inflammation of the eye, neurologic abnormalities and occasionally stiffness or lameness. Treatment of Lyme disease in horses, which entails the administration of antibiotics, is similar to the protocol for dogs; however, the extent of drug dispersal and effectiveness in horses is not fully understood. Given the ongoing range expansion of the tick vector and bacterial pathogen system in North America, equine Lyme disease is of increasing concern. Vaccination is not available for horses and the true extent of disease after an active infection is
unknown, which makes early diagnosis and treatment by a veterinarian even more important.
• Equine granulocytic anaplasmosis. Not to be confused with anaplasmosis in cattle due to Anaplasma marginale, this disease (equine granulocytic anaplasmosis) is caused by the tick-borne agent Anaplasma phagocytophilum, previously known as Ehrlichia equi. Black-legged ticks are the main vector for this pathogen. The disease is characterized by loss of appetite, lethargy, hemorrhage or lameness. In some horses the condition is self-limiting and does not require treatment, while others improve following administration of antibiotic therapy.
• Equine piroplasmosis. Although not known to be endemic in the United States, equine piroplasmosis (EP) presents a serious concern and regulatory precautions are in place to limit its introduction and spread. The disease is caused by protozoan Theileria equi and Babesia caballi, which circulate in the bloodstream. Dermacentor species, including wood ticks, winter ticks, and the infrequently encountered tropical horse ticks (Dermacentor nitens), can transmit these pathogens as they feed. Although less commonly seen in the United States, cayenne ticks (Amblyomma cajennense complex) were linked experimentally to a 2009 outbreak of EP caused by Theileria equi. Occasional cases of EP in the United States occur when horses are exposed to the pathogen through shared blood-contaminated equipment.
Mild forms of EP cause weakness and lack of appetite, while more severe signs include fever, anemia, weight loss, jaundiced mucous membranes, swelling of the limbs and abdomen and labored breathing. Clinical signs are usually related to destruction of red blood cells and low platelets. Treatment involves quarantine and anti-protozoal medication, which can take months to years to produce negative antibody tests. Even though most horses recover, some EP cases prove fatal. Regional outbreaks can lead veterinary health authorities to limit horse movement, resulting in industry disruptions. Unfortunately, infected horses are carriers of the pathogen for life. Therefore, when a case is suspected, state and federal veterinarians are notified to perform confirmatory diagnostics and manage the treatment protocol.
• Novel equine tick-borne infections. In addition to the known disease-causing agents transmitted by ticks, there are likely novel tickborne agents that have yet to be characterized or thoroughly described. For instance, preliminary research has documented the presence of antibodies to the bacteria Ehrlichia spp. in as many as 30 percent of horses in the central United States, and more commonly in those horses heavily infested with ticks. However, the potential health implications of these infections, if any, and the specific bacteria responsible have yet to be identified.
Tick paralysis. Although not caused by an infectious agent, ticks feeding on horses can occasionally lead to progressive weakness, ataxia and recumbency in afflicted horses. Referred to as “tick paralysis,” the condition usually occurs when ticks---most often wood ticks in North America---are simultaneously feeding and regurgitating salivary secretions that contain neurotoxins. These toxins interfere with nerve cell signals and can lead to ascending paralysis, which starts in the legs and moves up toward the body. Luckily, rapid recovery usually occurs after the removal of all feeding ticks.
A YEAR-ROUND THREAT
Ticks are active year-round, which means horses may be infested at any time if the weather and their habitat allows. As seasonal weather patterns shift, timing of tick activity also changes. And even though immature stages of some species may be found feeding on horses, adults are the stage most often collected. Therefore, the tick threat posed to horses is greatest when adults of each species are most active.
Questing activity varies depending on the region, but generally, lone star ticks, Gulf Coast ticks, wood ticks and longhorned ticks are found on horses in spring and summer. Research has demonstrated that, depending on climate and habitat at a given location, lone star ticks reach peak activity in May, Gulf Coast ticks in July and August, wood ticks in May, June, and July, and current data suggest longhorned ticks peak in July.
In contrast, winter ticks and blacklegged ticks (deer ticks) are most active during fall, winter and early spring. Winter ticks are most often collected from horses in Oklahoma in November, December, and January. Activity of
black-legged ticks (deer ticks) commonly peaks in October and November, with a second peak in March and April. Spinose ear ticks have been reported from animals year-round but typically are also more active in winter and spring.
Nobody likes thinking about ticks, but they can’t be avoided. Various tick species are active throughout the year, creating a perpetual equine health threat. Products and strategies for combatting tick infestations are relatively limited, but there are measures you can take to protect your horse. By increasing your awareness of the ticks in your area, as well as their seasonality and likely habitats, you can anticipate issues and work to keep them at bay.