Key Insights
  • Pedal osteitis is inflammation of the coffin bone that causes demineralization, weakening, and sometimes lameness
  • Pedal osteitis develops from repeated concussions, poor hoof conformation, chronic laminitis, or bacterial infection entering the hoof
  • Non-septic cases often cause soreness after exercise or trimming, while septic cases lead to severe pain, pus drainage, and fever
  • Diagnosis relies on lameness exams and radiographs, with advanced imaging used for difficult cases
  • Treatment may include corrective shoeing, rest, anti-inflammatories, antibiotics, or surgical debridement
  • Most horses recover well if treated promptly, though advanced cases risk lasting complications

Pedal osteitis in horses is a condition characterized by inflammation and damage to the pedal (coffin) bone within the hoof. Affected horses can experience pain and lameness, which may be worse after exercise or hoof trimming. [1]

Pedal osteitis typically develops as a result of chronic and repetitive trauma to the hoof, including exercising on hard surfaces, poor conformation or persistent laminitis. [1] It can also result from bacterial infections in the hoof capsule. [2]

Treatment aims to address the underlying cause of the hoof inflammation. This may involve antibiotics to treat infections, corrective trimming and shoeing to improve hoof balance, and anti-inflammatory medications or pain relief. In severe cases, surgery may be required to remove damaged tissue. [2][3]

The prognosis for horses with pedal osteitis depends on the underlying cause and the extent of the damage to the pedal bone. If the condition is treated promptly, many horses can return to normal function. Severe or advanced cases may lead to long-term lameness or complications. [3]

Pedal Osteitis in Horses

Pedal osteitis (PO) refers to inflammation of the pedal bone, also known as the coffin bone. This bone is located within the hoof capsule, and is the insertion point of the deep digital flexor tendon. [1]

Inflammation of the pedal bone causes demineralization, or loss of mineral within the bone structure. This can cause weakening of the bone, lameness, and even bone fractures. [1]

Pedal osteitis is more common in a mature horse’s front limbs, which bear more weight than the hind limbs. The condition can affect one limb (unilateral) or both limbs (bilateral) depending on the underlying cause of the condition. [1]

Causes

Pedal osteitis can be either septic (related to bacterial infection) or non-septic (no bacteria involved). Most cases are septic and occur due to spread of infection from a hoof abscess. [1]

Non-septic Pedal Osteitis

Non-septic pedal osteitis results from chronic inflammation within the hoof, not related to bacterial infections. Causes of non-septic PO include: [1]

Conformational traits and trimming mistakes that predispose to non-septic PO include: [4]

  • Low heels or long toes that lead to flat soles
  • Upright foot conformation
  • Club feet

Septic Pedal Osteitis

Septic pedal osteitis refers to a bacterial infection of the pedal bone. [1]

In adult horses, septic PO typically requires introduction of bacteria into the hoof capsule, allowing the bacteria to infect the bone. Causes include: [1]

Foals

Septic PO can also occur in foals, usually from the spread of bloodborne bacteria to the pedal bone. [1] The most common bacteria causing PO in foals include: [5]

  • Escherichia coli
  • Actinobacillus
  • Streptococcus
  • Enterobacter
  • Salmonella

Foals experiencing failure of passive transfer have a higher risk of septic PO. [6] The pedal bone may have a higher risk of developing infection over other bones as there are several vessels that make sharp turns within the pedal bone, encouraging bacteria to proliferate at these sites. [5]

Symptoms

The main symptom of PO is lameness. Depending on the cause of the condition, the lameness can range from mild to severe. [1]

PO is most common in the front limbs in adult horses. In foals, the hind limbs are most commonly affected. [1]

Non-septic Pedal Osteitis

Symptoms of non-septic PO in horses include: [1]

  • Lameness that is worse after exercise
  • Lameness that is worse after trimming or shoeing

The severity of lameness in non-septic PO is variable, and horses may show signs of lameness on multiple limbs. [1] Some horses may show a sudden onset of lameness after an exercise session, then recover after a few days of stall rest. [4]

Septic Pedal Osteitis

Most horses with septic PO show severe lameness. [1][6] Additional symptoms include: [1][7]

  • Elevated temperature of the hoof capsule
  • Prominent digital pulses
  • Drainage tract in the hoof sole leaking pus
  • Fever

Diagnosis

Diagnosis of PO typically involves a thorough lameness examination, to identify the source of lameness. By careful examination, the veterinarian can determine that the source of pain is in the hoof, and from there perform diagnostics to identify the cause.

Hoof Testers

Applying hoof testers is a common component in any lameness examination. Horses with non-septic PO tend to show significant sensitivity over the entire sole when squeezed with hoof testers. [1]

Horses with septic PO tend to have more focal pain, usually directly over the abscess or wound that caused the PO. [1]

Perineural Anesthesia

Perineural anesthesia, or “nerve blocks” are a common method for identifying the source of lameness during a lameness examination.

Most cases of non-septic PO will show complete resolution of lameness with a palmar/plantar distal (PD) nerve block, also known as a low posterior digital block, which blocks feeling to the heel and sole. [1]

Conversely, most cases of septic PO continue to show lameness with a PD nerve block. [1] Usually, these horses require an abaxial sesamoid nerve block to resolve their lameness, as this nerve block numbs the entire hoof. [6]

Radiographs (X-rays)

Once the veterinarian localizes the lameness to the hoof, radiographic images (X-rays) can help identify the cause of lameness within the hoof structure.

Signs of non-septic PO on X-rays include: [1]

  • Loss of normal mineral content in the bone
  • Loss of bone around the blood vessels of the solar margin, the outer edge of the pedal bone and widening of the vascular channels within the bone
  • Irregular pattern to the bone along the solar margin
  • Possible fractures along the solar margin

Some sound horses also show loss of mineral content and widening of the vascular channels, likely due to a previous injury or condition within the foot. [8] Typically, more advanced diagnostic methods are required to confirm a diagnosis. [4]

Septic PO has a similar appearance to non-septic PO, however the bone loss usually affects a focal area, rather than the entire pedal bone. Most cases of septic PO occur at the solar margin. [1]

Other findings of septic PO include: [9]

  • Gas shadows within the hoof capsule
  • Fractures of the pedal bone
  • Separate fragments of pedal bone

Advanced Diagnostic Imaging

Non-septic pedal osteitis may require nuclear scintigraphy or magnetic resonance imaging (MRI) to diagnose. Both of these diagnostic imaging types can highlight active inflammation and swelling, allowing for diagnosis. [4]

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Treatment

The treatment for pedal osteitis in horses varies based on its underlying cause. In both septic and non-septic cases, the primary objective is to alleviate inflammation, manage pain, and provide protection for the hoof and sole as it heals.

Non-septic Pedal Osteitis

Treating non-septic pedal osteitis focuses on reducing concussion to the foot, so that the inflammation within the pedal bone can subside. [1]

Typically, this requires shoeing changes to reduce the concussive forces acting on the hoof when the horse moves. Options for corrective shoeing may include: [1][4]

  • A wide-webbed shoe which provides additional support for the hoof wall and sole
  • Shoes with a rolled or rockered toe
  • Rim pads which provide padding to the outer edges of the hoof
  • Full pads which provide padding for the entire hoof sole
  • Onion heel shoes or bar shoes if the heel area of the pedal bone is affected

Many horses will require specialized shoeing for the remainder of their performance career, to prevent recurrence of PO. [4]

Most horses also require a period of stall rest to recover from non-septic PO. [1] Typically, 60 to 90 days of stall rest before gradually returning to training is recommended. [4]

Septic Pedal Osteitis

Since septic PO is a bacterial infection, antibiotics are a critical component of the treatment plan. In some cases, surgical removal of affected bone is also necessary.

Systemic Antibiotics

Systemic antibiotics are medications given through injection that treat all of the horse’s body systems. Oral and even intramuscular antibiotics do not effectively treat infections of bone on their own. The most common antibiotics used for skeletal infections include:

  • Penicillin and gentamicin
  • Trimethoprim-sulfa
  • Doxycycline
  • Enrofloxacin
  • Chloramphenicol

Regional Limb Perfusion

Although intravenous antibiotics can be effective on their own, they require either prolonged hospitalization, daily vet visits or difficult to manage indwelling catheters. Oral or intramuscular antibiotics often do not reach a high enough concentration (dose of antibiotic) in the specific area that the veterinarian wants to treat.

Regional limb perfusion (RLP) is a method of delivering a high dose of antibiotics to a local area, for maximum efficacy.

To perform RLP, the veterinarian applies a tourniquet to the lower limb, just above the hoof. They then inject antibiotics into a blood vessel below the tourniquet. The tourniquet keeps the antibiotics within the desired area for 20-30 minutes, allowing a high concentration of antibiotic to treat the affected area. [6]

The most common antibiotics used for RLP are: [6]

  • Amikacin
  • Gentamicin
  • Penicillin
  • Ampicillin
  • Enrofloxacin

Some referral hospitals also offer intraosseous regional limb perfusions, where a surgeon injects antibiotics directly into the affected bone. In this procedure, the surgeon drills a hole into the bone and places a catheter into the hole, allowing administration of antibiotics over several days. Intraosseous RLP may show better results for pedal osteitis compared to traditional RLP. [6]

Antibiotic-Impregnated Materials

Some cases of septic PO may benefit from surgical placement of antibiotic-impregnated materials, which slowly release high concentrations of an antibiotic over a set period of time. [6]

The most common material used is polymethylmethacrylate (PMMA), shaped into beads. [6][10] Most of these impregnated materials contain the antibiotic amikacin. [6]

Surgical Debridement

Debridement refers to removal of diseased tissue. Some cases of septic pedal osteitis may require surgical debridement for the horse to fully recover. [6]

The surgeon usually starts from the hoof sole, then works inward removing any diseased bone and tissue. [6] If there is a draining tract present, the surgeon can follow the draining tract directly to the site of infection. [7]

Studies show that up to 24% of the pedal bone can be removed surgically without causing long-term lameness issues. [6]

Sequestra

Septic PO cases are prone to developing sequestra, or fragments of dead bone that have separated from the rest of the pedal bone. [9][11] These sequestra must be completely removed through surgical debridement for healing to occur.

Depending on the location of the sequestrum, additional surgical sites or more aggressive debridement may be required to remove the bone fragment. These horses may require a supportive shoe immediately after treatment, to prevent the hoof wall from collapsing or splitting under the horse’s weight. [7]

Anesthesia

Many surgeons prefer to perform debridement under general anesthesia to allow for thorough removal of affected tissue. [6] Another option is standing anesthesia, where the horse is sedated but remains standing.

Deciding between general and standing anesthesia is up to the surgeon’s discretion. Potential benefits of standing anesthesia include: [11]

  • Less costly for the owner
  • Less risk during recovery from anesthesia for the horse

One study showed no difference in outcome between cases performed under general anesthesia versus standing anesthesia. [12]

Wound Management

Following surgical debridement, the hoof requires significant aftercare to protect the surgical site from re-infection. The surgeon typically packs the wound with gauze soaked in antiseptics, then bandages the hoof. [7]

Daily bandage changes are necessary until the wound heals over. [7] The benefits of bandaging during the early phases of healing include: [13]

  • Preventing excessive granulation tissue formation (proud flesh)
  • Absorbs any draining pus
  • Keeps topical medications in contact with the surgical site
  • Protects the wound from contamination and drying out

Granulation tissue typically fills in the surgical site within 7-10 days. At this point, a treatment plate (a specialized shoe with a removable plate covering the entire sole) is applied as a more long-term method of protecting the surgical area. [7]

Once the treatment plate is in place, application of iodine to the granulation tissue every few days can help speed keratinization, which is the process of forming hoof wall tissue. [7]

Most surgical sites are completely healed by 12 weeks after debridement. [7] Some horses may require up to 12 months of stall rest for complete recovery from the procedure. [9]

Prognosis

The prognosis for PO is very good to excellent with appropriate treatment. Most horses make a complete recovery and return to their previous level of performance. [1]

Non-septic Pedal Osteitis

Non-septic cases of PO identified early in development have the best prognosis, as well as cases where the horse’s exercise environment can be controlled long-term. Factors associated with a poorer prognosis include: [1]

  • Continuing to exercise on hard surfaces
  • PO associated with chronic laminitis

Septic Pedal Osteitis

For horses with septic PO, most have an excellent prognosis, even in cases that develop complications such as pedal bone fractures and sequestra. [1] One study showed 73% of horses returned to their previous or expected level of performance after treatment. [11]

Additionally, most foals with septic PO survive, and many go on to performance careers. [1][5] One study showed that 86% of treated foals survived the initial treatment period, with 50% successfully starting a racing career. [5]

Complications that can arise from septic PO include: [10]

  • Recurrence of infection
  • Fracture of the pedal bone
  • Spread of the infection to the navicular bursa or coffin joint

Frequently Asked Questions

Here are some frequently asked questions about pedal osteitis in horses:

Summary

  • Pedal osteitis in horses refers to inflammation of the pedal bone (coffin bone) within the horse’s hoof
  • Lameness is the main symptom of pedal osteitis
  • Bacterial infections from hoof abscesses are the primary cause of pedal osteitis
  • The overall prognosis of pedal osteitis is good to excellent
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References

  1. Baxter, G.M. Manual of Equine Lameness. Wiley & Sons, Inc. 2021.
  2. Baker, G. et al., Distal phalanx: pedal osteitis – septic. Vetlexicon Equis. ISSN 2398-2977.
  3. Munroe, G., Distal phalanx: pedal osteitis – non-septic. Vetlexicon Equis. ISSN 2398-2977.
  4. Morrison. S. E., The Thoroughbred Racehorse Foot: Evaluation and Management of Common Problems. AAEP Proceedings. 2013.
  5. Neil. K. M. et al., Septic Osteitis of the Distal Phalanx in Foals: 22 Cases (1995–2002). Journal of the American Veterinary Medical Association. 2007. doi: 10.2460/javma.230.11.1683.View Summary
  6. Baxter, G.M. Adams and Stashak’s lameness in horses. 7th edition. Wiley-Blackwell. 2020.
  7. Honnas. C. M. et al., Hoof Wall Surgery in the Horse: Approaches to and Underlying Disorders. Veterinary Clinics of North America: Equine Practice. 2003. View Summary
  8. Moyer. W., Nonseptic Pedal Osteitis: A Cause of Lameness and a Diagnosis?. Proceedings of the Annual Convention of the AAEP 1999. 1999.
  9. Cauvin. E. R. J. and Munroe. G. A., Septic Osteitis of the Distal Phalanx: Findings and Surgical Treatment in 18 Cases. Equine Veterinary Journal. 1998. View Summary
  10. Céleste. C. J. and Szöke. M. O., Management of Equine Hoof Injuries. Veterinary Clinics of North America: Equine Practice. 2005. View Summary
  11. O’Brien. T. and Hunt. R. J., Recent Advances in Standing Equine Orthopedic Surgery. Veterinary Clinics of North America: Equine Practice. 2014. View Summary
  12. Cillán-Garcia. E. et al., Comparison of Long-Term Outcome Following Surgical Treatment of Septic Pedal Osteitis in Horses under Standing Sedation and General Anaesthesia. Equine Veterinary Journal. 2018.
  13. Redding. W. R. and O’Grady. S. E., Septic Diseases Associated with the Hoof Complex. Veterinary Clinics of North America: Equine Practice. 2012. View Summary