Sheep and Goat Foot Rot: Lesion Scoring, Treatment, and Eradication Planning

Foot rot in sheep and goats is a contagious bacterial disease caused primarily by Dichelobacter nodosus, often in synergy with Fusobacterium necrophorum. This article provides veterinarians with a clinical guide to diagnosing and managing foot rot, including lesion scoring, treatment protocols, and eradication strategies. The content is based on approved sources and focuses on practical decision-making for veterinary practitioners working with sheep and goat producers.

At a Glance: Foot Rot Management Overview

Clinical Signs and Differential Diagnosis

Interdigital Dermatitis and Underrunning of Horn

The earliest clinical sign of foot rot is interdigital dermatitis, characterized by moist, reddened, and malodorous skin between the claws. As the disease progresses, the infection undermines the horn of the hoof wall, causing separation from the underlying sensitive tissue. This underrunning typically begins at the heel and extends forward, creating a characteristic pocket of necrotic material. Affected animals show varying degrees of lameness, from mild stiffness to non-weight-bearing on the affected limb.

The distinction between virulent and benign foot rot is critical for prognosis and eradication planning. Virulent strains of Dichelobacter nodosus cause progressive underrunning of the horn that can lead to complete hoof capsule loss. Benign strains typically cause only interdigital dermatitis or mild underrunning that resolves spontaneously under dry conditions. However, benign strains can cause severe outbreaks under wet, muddy conditions, as documented in an alpine ibex colony in the Swiss prealps (https://doi.org/10.17236/sat00021).

Differential Diagnoses

Conditions that mimic foot rot include:

• Foot abscess: Usually involves a single claw with a discrete pus pocket, often caused by Fusobacterium necrophorum or Trueperella pyogenes. Unlike foot rot, the infection does not spread between claws or between animals.
• Contagious ovine digital dermatitis (CODD): Caused by Treponema species, CODD typically starts at the coronary band and causes severe lameness with separation of the hoof capsule from the coronary band downward. It does not respond to standard foot rot treatments.
• Laminitis: Bilateral forelimb lameness with hoof wall rings, often associated with grain overload or lush pasture.
• Traumatic injury: Sudden onset lameness with visible wound or swelling, affecting only one limb.
• White line disease: Separation at the white line with dirt and debris packed into the defect, usually in individual animals.

Lesion Scoring Systems

The 0 to 5 Scale

Standardized lesion scoring is essential for monitoring disease progression, evaluating treatment efficacy, and planning eradication programs. The most widely used system assigns a score from 0 to 5 based on the extent of interdigital and horn involvement:

• Score 0: Normal foot, no lesions.
• Score 1: Mild interdigital dermatitis with slight reddening and moisture between the claws. No underrunning of horn.
• Score 2: Moderate interdigital dermatitis with more pronounced inflammation and a foul odor. Early underrunning of the horn at the heel, extending less than 1 cm.
• Score 3: Underrunning of the horn extending 1 to 2 cm from the heel, with necrotic material visible. The animal is moderately lame.
• Score 4: Extensive underrunning involving more than half of the hoof wall, with complete separation of the horn from the sensitive tissue. Severe lameness.
• Score 5: Complete loss of the hoof capsule, with exposed sensitive tissue. The animal is severely lame and may be recumbent.

Practical Application in the Field

When scoring lesions, examine all four feet of each animal in good light. Clean the feet with a hoof knife to remove superficial dirt and debris. Record the highest score for any foot, as this reflects the overall disease burden. For eradication programs, score every animal in the flock at each examination, beyond lame animals, because subclinical infections can maintain the disease cycle.

The scoring system allows veterinarians to classify flocks into categories:

• Low prevalence: Less than 5% of animals with score 2 or higher.
• Moderate prevalence: 5% to 20% of animals with score 2 or higher.
• High prevalence: More than 20% of animals with score 2 or higher.

This classification guides the intensity of intervention required. Low-prevalence flocks may be candidates for targeted culling, while high-prevalence flocks typically require whole-flock treatment and vaccination.

Diagnostic Testing

Bacterial Culture

Traditional culture for Dichelobacter nodosus requires specialized anaerobic conditions and selective media. Samples are collected from the advancing edge of the underrunning horn using a sterile swab or biopsy punch. The organism is fastidious and slow-growing, requiring 5 to 7 days of incubation. Culture has limited sensitivity, particularly in chronic cases where secondary bacteria overgrow the primary pathogen. The prevalence of Dichelobacter nodosus in western Austrian sheep flocks was compared using bacterial cultures, clinical foot rot and lameness with PCR and analysis of sample pooling for PCR diagnosis (https://doi.org/10.17236/sat00427).

Polymerase Chain Reaction (PCR)

PCR has largely replaced culture for diagnosis of foot rot because of its higher sensitivity and ability to detect Dichelobacter nodosus even in mixed infections. PCR can also differentiate between virulent and benign strains by targeting the aprV2 (virulent) and aprB2 (benign) genes. This strain typing is essential for eradication planning, as only virulent strains warrant aggressive intervention. Identification and grouping of Dichelobacter nodosus using PCR and sequence analysis allows precise characterization of circulating strains (https://doi.org/10.1006/mcpr.1998.0210).

Sample pooling is a cost-effective strategy for flock-level screening. Swabs from multiple animals can be combined into a single PCR reaction, reducing laboratory costs while maintaining adequate sensitivity. The optimal pool size depends on the expected prevalence and the sensitivity of the PCR assay. For flocks with low expected prevalence, smaller pools (3 to 5 animals) are recommended to avoid dilution effects.

Sample Collection Protocol

1. Restrain the animal in lateral recumbency or use a tilt table.
2. Clean the affected foot with a dry brush to remove gross contamination.
3. Using a sterile swab or biopsy punch, collect material from the advancing edge of the underrunning horn, where the active infection is present.
4. Place the sample in transport medium appropriate for anaerobic bacteria (e.g., Amies gel with charcoal).
5. Refrigerate samples and ship to the laboratory within 24 hours.
6. For PCR, samples can be stored frozen at -20 degrees C for up to 6 months.

Treatment Options

Footbathing

Footbathing is a cornerstone of foot rot control in sheep and goats. The goal is to reduce the bacterial load on the feet and prevent new infections. Common footbath solutions include:

• Zinc sulfate (10% solution): Effective against Dichelobacter nodosus and Fusobacterium necrophorum. Requires a contact time of at least 10 minutes. The solution must be kept clean and replaced after every 100 to 200 sheep.
• Copper sulfate (5% solution): Also effective but stains wool and can be toxic if ingested. Not recommended for use on wet or muddy feet.
• Formalin (3% to 5% solution): Effective but irritating to skin and respiratory tract. Banned in some countries due to carcinogenicity concerns.

Footbathing is most effective when combined with hoof trimming and dry standing conditions. Animals should stand in the footbath for the recommended contact time, then move onto a dry concrete or gravel area to allow the solution to dry on the feet. Repeated footbathing at 2 to 4 week intervals is typically required to achieve control.

Topical Antibiotics

Topical antibiotics can be applied directly to affected feet after trimming. Options include:

• Oxytetracycline spray: Applied to the cleaned and trimmed foot. Provides local antibacterial activity against Dichelobacter nodosus and secondary invaders.
• Lincomycin/spectinomycin spray: Another topical option with activity against gram-positive anaerobes.

Topical treatment is most effective for mild to moderate lesions (scores 1 to 3). For severe lesions (scores 4 to 5), systemic antibiotics may be necessary. The effects of topical treatment of foot rot in sheep using ozonated olive ointment have been investigated as an alternative to conventional antibiotics (https://pubmed.ncbi.nlm.nih.gov/34917851).

Systemic Antibiotics

Systemic antibiotics are indicated for severe foot rot, particularly when multiple feet are affected or when the animal is systemically ill. The choice of antibiotic should be based on culture and sensitivity results when possible. Common options include:

• Procaine penicillin: Effective against Dichelobacter nodosus and Fusobacterium necrophorum. Requires daily injection for 3 to 5 days.
• Oxytetracycline: Long-acting formulations allow single-dose treatment. Effective against both pathogens.
• Tulathromycin: A single-dose macrolide antibiotic with activity against Dichelobacter nodosus.

Veterinarians must comply with local regulations regarding antibiotic use in food animals, including withdrawal periods for meat and milk. Systemic antibiotics should be reserved for cases where topical treatment and footbathing have failed or are impractical.

Hoof Trimming

Hoof trimming is an essential component of foot rot treatment. The goal is to remove all undermined and necrotic horn, exposing the infected tissue to air and topical treatments. Trimming should be performed carefully to avoid damaging the sensitive laminae and causing pain or bleeding.

Trimming protocol:

1. Restrain the animal securely.
2. Clean the foot with a brush and water.
3. Using a hoof knife or nippers, remove all loose and undermined horn.
4. Pare back the horn until the junction between healthy and diseased tissue is visible.
5. Remove any necrotic material from the interdigital space.
6. Apply topical antibiotic or antiseptic to the exposed area.
7. Keep the animal on dry, clean bedding for 24 to 48 hours after trimming.

Over-trimming can cause pain and delay healing. In severe cases, trimming may need to be repeated at 2 to 4 week intervals until the hoof regrows normally.

Eradication Planning

Quarantine and Biosecurity

Eradication of foot rot from a flock requires strict biosecurity measures to prevent reintroduction of the pathogen. Key steps include:

• Quarantine new arrivals: Isolate all purchased animals for at least 4 weeks. Examine feet on arrival and again before release into the main flock.
• Separate infected and clean groups: Maintain separate handling facilities, pastures, and equipment for infected and uninfected animals.
• Footbath at entry and exit: Place footbaths at the entrance to handling facilities and at the boundary between clean and infected areas.
• Control traffic: Limit visitor access to the farm. Require clean boots and clothing for all personnel entering animal areas.

Culling Strategies

Culling persistently infected animals is often necessary for eradication. Animals that fail to respond to treatment after two or three cycles of trimming and footbathing are likely chronic carriers. These animals may have deep-seated infections in the hoof that are inaccessible to topical treatment.

Culling criteria:

• Animals with score 4 or 5 lesions that do not improve after two treatments.
• Animals with recurrent foot rot after apparent recovery.
• Animals with chronic hoof deformities that predispose to reinfection.
• Older animals with multiple episodes of foot rot.

Culling should be combined with replacement from foot rot-free sources. Purchasing animals from flocks with a known negative status reduces the risk of reintroduction.

Vaccination

Vaccination against Dichelobacter nodosus can be a useful adjunct to eradication programs. Vaccines are typically bacterins containing multiple serogroups of the organism. They reduce the severity of lesions and the duration of infection but do not prevent infection entirely.

Vaccination protocol:

• Administer two doses 4 to 6 weeks apart, followed by annual boosters.
• Vaccinate all animals in the flock, including lambs over 4 weeks of age.
• Combine vaccination with footbathing and trimming for best results.

Vaccination is most effective when the circulating strain is included in the vaccine. Strain typing by PCR can guide vaccine selection. In flocks with multiple serogroups, a multivalent vaccine is recommended.

Whole-Flock Treatment Protocols

Elimination of virulent strains of Dichelobacter nodosus from sheep flocks is achievable with a systematic approach. A proof of concept study demonstrated elimination of virulent strains (aprV2) from feet of 28 Swiss sheep flocks (https://doi.org/10.1016/j.tvjl.2016.06.015). The protocol typically involves:

1. Initial assessment: Score all animals and collect samples for PCR to confirm the presence of virulent strains.
2. Treatment phase: Trim all affected feet, footbath the entire flock, and administer systemic antibiotics to animals with score 3 or higher.
3. Follow-up: Re-examine and re-score all animals at 2 to 4 week intervals. Repeat treatment for any animals with persistent lesions.
4. Culling: Remove animals that fail to respond after two treatment cycles.
5. Testing: PCR test a representative sample of the flock (e.g., 30 to 60 animals) to confirm elimination.
6. Maintenance: Maintain biosecurity measures and monitor for recurrence.

The entire process typically takes 6 to 12 months, depending on the initial prevalence and the cooperation of the producer.

Records and Measurements

Flock-Level Monitoring

Accurate records are essential for tracking progress and identifying problem animals. For each examination, record:

• Date and examiner name.
• Animal identification (ear tag, tattoo, or electronic ID).
• Lesion score for each foot (0 to 5).
• Treatment administered (footbath, topical, systemic, trimming).
• Outcome at next examination (improved, same, worse).

A simple spreadsheet or farm management software can be used to track individual animal histories. At the flock level, calculate:

• Prevalence: Percentage of animals with score 1 or higher.
• Incidence: Number of new cases per unit time.
• Treatment success rate: Percentage of treated animals that improve by at least one score at the next examination.
• Culling rate: Percentage of animals culled due to foot rot.

Environmental Monitoring

Environmental conditions strongly influence foot rot transmission. Record:

• Rainfall and pasture moisture levels.
• Condition of laneways and handling yards (muddy, dry, well-drained).
• Stocking density on pasture.
• Frequency of footbathing and footbath solution changes.

Wet, muddy conditions favor survival of Dichelobacter nodosus in the environment and increase transmission rates. During dry periods, the organism dies quickly on pasture, allowing natural recovery in some animals.

Common Failure Patterns

Incomplete Treatment

The most common cause of treatment failure is incomplete removal of undermined horn. If necrotic material remains under the hoof wall, topical treatments cannot reach the infection site, and the animal remains a source of infection for the flock. Proper trimming technique and adequate restraint are essential for thorough debridement.

Reinfection from the Environment

Dichelobacter nodosus can survive in the environment for up to 2 weeks under moist conditions. If treated animals return to contaminated pastures or handling facilities, they are likely to become reinfected. Eradication programs must include environmental management, such as resting pastures for 2 to 4 weeks and cleaning and disinfecting handling facilities.

Carrier Animals

Some animals carry Dichelobacter nodosus without showing clinical signs. These subclinical carriers can reintroduce infection to a clean flock. PCR testing of apparently healthy animals is necessary to identify carriers. Animals with a history of foot rot should be considered potential carriers even after clinical recovery.

Strain Variation

Benign strains of Dichelobacter nodosus can cause severe disease under favorable environmental conditions. Flocks that test positive for benign strains may still experience outbreaks during wet weather. Conversely, virulent strains may cause mild disease in well-managed flocks with good nutrition and dry conditions. Strain typing by PCR is essential for accurate prognosis and treatment planning.

Poor Biosecurity

Eradication programs fail when new infections are introduced from outside the flock. Common sources of reintroduction include:

• Purchased animals that were not quarantined.
• Shared equipment or handling facilities with infected flocks.
• Visitors or farm personnel who move between flocks.
• Wildlife, such as deer or feral goats, that may carry the organism.

Welfare and Safety Context

Pain and Lameness

Foot rot is a painful condition that causes significant welfare compromise. Affected animals show reduced feed intake, weight loss, and decreased milk production. Severe lameness can prevent animals from reaching feed and water, leading to starvation and death in extreme cases. Prompt treatment is essential to minimize suffering.

Veterinarians should advise producers to treat lame animals as a priority, even if this disrupts the treatment schedule for the rest of the flock. Analgesia should be considered for animals with score 4 or 5 lesions, particularly when trimming is required. Non-steroidal anti-inflammatory drugs (NSAIDs) can provide pain relief and reduce inflammation.

Zoonotic Risk

Foot rot is not zoonotic, Dichelobacter nodosus does not infect humans. However, the chemicals used in footbaths (e.g., formalin, copper sulfate) can be hazardous to human health. Personal protective equipment, including gloves and eye protection, should be worn when handling footbath chemicals. Formalin is a known carcinogen and should be used only in well-ventilated areas.

Antibiotic Stewardship

Systemic antibiotics should be used judiciously to minimize the risk of antimicrobial resistance. Culture and sensitivity testing should guide antibiotic selection whenever possible. Veterinarians must comply with local regulations regarding antibiotic use in food animals, including withdrawal periods for meat and milk. Topical treatment and footbathing should be the first line of defense, with systemic antibiotics reserved for severe cases.

Professional Escalation Criteria

When to Refer to a Specialist

Most cases of foot rot can be managed by the farm veterinarian. However, referral to a veterinary specialist or diagnostic laboratory is indicated when:

• The flock fails to respond to standard treatment after two cycles.
• PCR testing is needed for strain typing or confirmation of eradication.
• The flock has a high prevalence of severe lesions (score 4 or 5) despite treatment.
• There is suspicion of CODD or other differential diagnoses that require specialized testing.
• The producer is considering an eradication program and needs a detailed plan.

When to Involve Regulatory Authorities

In some jurisdictions, foot rot is a notifiable disease. Veterinarians should be aware of local regulations regarding reporting and control. Regulatory authorities may provide assistance with testing, quarantine, and compensation for culled animals. Involvement of regulatory authorities is particularly important when:

• The flock is part of a regional eradication program.
• The disease is spreading to neighboring flocks.
• There is evidence of a new or emerging strain of Dichelobacter nodosus.

Practical Decision Framework for Foot Rot Management: A Step-by-Step Approach for Veterinarians

Clinical Decision Algorithm for Individual Animal Treatment

When examining a sheep or goat with lameness, a structured decision algorithm helps standardize treatment and avoid common errors. Begin with a complete foot examination of all four feet, cleaning each foot with a hoof knife to remove surface debris. Record the lesion score for each foot using the 0 to 5 scale described in the lesion scoring section. The following algorithm guides treatment decisions based on the highest score recorded on any foot.

For score 0 (normal foot): No treatment required. Record the animal as clinically normal. If the animal is part of an eradication program, consider PCR testing to rule out subclinical carriage, particularly if the animal has a history of foot rot or comes from a high-prevalence group.

For score 1 (mild interdigital dermatitis): Apply topical oxytetracycline spray to the interdigital space after cleaning. No hoof trimming is necessary unless debris is trapped between the claws. Footbath the animal as part of the flock treatment protocol. Re-examine in 2 to 3 weeks. If the lesion has not resolved, escalate to score 2 treatment.

For score 2 (moderate interdigital dermatitis with early underrunning): Trim away any loose horn at the heel using a hoof knife. Remove necrotic material from the underrunning pocket. Apply topical oxytetracycline spray or lincomycin/spectinomycin spray to the exposed area. Footbath the animal in 10% zinc sulfate for 10 minutes. Re-examine in 2 weeks. If the lesion has not improved by at least one score, escalate to score 3 treatment.

For score 3 (underrunning extending 1 to 2 cm): Perform thorough hoof trimming to remove all undermined horn. Pare back to healthy tissue, taking care not to damage the sensitive laminae. Apply topical antibiotic spray. Administer systemic antibiotics if the animal is moderately lame or if multiple feet are affected. Footbath the animal. Re-examine in 2 weeks. If the lesion has not improved, consider culling or referral for specialist evaluation.

For score 4 (extensive underrunning involving more than half the hoof wall): Trim all loose and undermined horn. This may require removal of most of the hoof wall. Apply a protective bandage if bleeding occurs. Administer systemic antibiotics for 3 to 5 days. Provide analgesia with a non-steroidal anti-inflammatory drug. Keep the animal on dry, clean bedding for 48 hours. Re-examine in 2 weeks. If the lesion has not improved significantly, culling is recommended.

For score 5 (complete hoof capsule loss): This is a severe welfare emergency. Provide immediate analgesia and systemic antibiotics. Clean the exposed sensitive tissue gently with dilute antiseptic solution. Apply a protective bandage. The animal should be housed on deep, dry bedding. Prognosis for recovery is guarded. If the animal does not show signs of healing within 2 weeks, euthanasia or culling is the most humane option.

Flock-Level Decision Matrix for Eradication Planning

The decision to pursue eradication versus control depends on several factors, including prevalence, strain type, producer commitment, and economic considerations. The following matrix helps veterinarians guide producers through this decision.

For flocks with favorable factors, a full eradication program is feasible and likely to succeed. For flocks with unfavorable factors, a control program focused on reducing lameness and economic losses may be more realistic. The proof of concept study demonstrating elimination of virulent strains from 28 Swiss sheep flocks used a systematic approach that included whole-flock treatment, repeated testing, and culling of non-responders (https://doi.org/10.1016/j.tvjl.2016.06.015).

Treatment Protocol Selection Based on Flock Size and Facilities

Flock size and available facilities influence the practical choice of treatment protocols. The following comparisons help veterinarians match protocols to farm conditions.

Small flocks (less than 100 animals): Individual animal treatment is feasible. Each animal can be examined, trimmed, and treated individually. Footbathing can be done using a portable footbath or even a plastic tub. Systemic antibiotics can be administered to individual animals as needed. This approach allows precise targeting of treatment but requires more labor per animal.

Medium flocks (100 to 500 animals): A combination of individual and group treatment is practical. Lame animals are examined and treated individually, while the rest of the flock receives group footbathing. Hoof trimming is reserved for animals with score 2 or higher. Systemic antibiotics are used selectively for severe cases. This approach balances labor efficiency with treatment effectiveness.

Large flocks (more than 500 animals): Group treatment protocols are necessary for practical management. The entire flock is footbathed at regular intervals, typically every 2 to 4 weeks. Hoof trimming is performed on a rolling basis, with animals processed through a handling system. Systemic antibiotics may be administered to groups of animals with high lesion scores. This approach is less targeted but can achieve population-level control.

Record System for Individual Animal Tracking

A practical record system is essential for monitoring treatment outcomes and identifying chronic carriers. The following template can be adapted for paper or electronic records.

Individual Animal Treatment Record

For flock-level monitoring, calculate the following metrics at each examination:

• Prevalence of lameness: Number of animals with score 2 or higher divided by total animals examined, multiplied by 100.
• Mean lesion score: Sum of highest scores for all animals divided by total animals examined.
• Treatment success rate: Number of animals that improved by at least one score divided by number treated, multiplied by 100.
• Culling rate: Number of animals culled due to foot rot divided by total animals in flock, multiplied by 100.

These metrics allow veterinarians to track progress over time and identify when the program is not achieving expected results.

Troubleshooting Common Treatment Failures

When treatment fails to produce expected improvement, systematic troubleshooting can identify the underlying cause. The following guide addresses common failure patterns.

Failure pattern 1: Lesions improve but recur within 2 to 4 weeks

Possible causes:

• Incomplete hoof trimming leaving necrotic material under the hoof wall
• Reinfection from contaminated environment
• Subclinical carrier animals reintroducing infection

Actions:

• Re-examine the affected animal and re-trim the foot, ensuring all undermined horn is removed
• Assess environmental conditions and recommend resting pastures for 2 to 4 weeks
• PCR test a sample of apparently healthy animals to identify carriers

Failure pattern 2: Lesions do not improve despite repeated treatment

Possible causes:

• Incorrect diagnosis (consider CODD, foot abscess, or white line disease)
• Deep-seated infection inaccessible to topical treatment
• Antibiotic resistance or inappropriate antibiotic choice
• Chronic hoof deformity preventing healing

Actions:

• Collect samples for culture and sensitivity testing
• Consider PCR to confirm Dichelobacter nodosus and rule out other pathogens
• Evaluate the animal for chronic hoof changes that may require culling

Failure pattern 3: New cases continue to appear despite treatment of affected animals

Possible causes:

• High environmental contamination
• Introduction of new infected animals
• Inadequate footbathing protocol (wrong concentration, contact time, or frequency)
• Benign strain causing severe disease under wet conditions

Actions:

• Review biosecurity protocols and quarantine procedures
• Test footbath solution concentration and contact time
• PCR test new cases to determine strain type
• Increase footbathing frequency during wet weather

Failure pattern 4: Flock-level prevalence does not decrease over time

Possible causes:

• Incomplete treatment coverage (some animals missed)
• Chronic carriers not identified or culled
• Reinfection from outside sources
• Producer non-compliance with treatment protocol

Actions:

• Audit treatment records to ensure all animals were examined and treated
• Review culling criteria and ensure consistent application
• Investigate potential sources of reintroduction
• Discuss compliance issues with the producer

Comparison of Treatment Approaches for Different Farm Types

The optimal treatment approach varies by farm type and production system. The following comparison helps veterinarians tailor recommendations.

Dairy sheep or goat farms: Milk withdrawal periods for systemic antibiotics are a major constraint. Topical treatment and footbathing are preferred. Systemic antibiotics should be used only when absolutely necessary and with careful attention to withdrawal periods. Frequent handling for milking allows regular foot inspection and early detection of lesions. Footbathing can be incorporated into the milking routine.

Meat sheep farms: Withdrawal periods for meat are shorter than for milk, making systemic antibiotics more practical. However, treatment costs must be balanced against the value of the animal. Culling of chronic carriers is often economically justified. Footbathing can be done at handling events such as weaning or vaccination.

Purebred breeding flocks: These flocks have high individual animal value, justifying more intensive treatment. Individual animal records are essential. PCR testing and strain typing are recommended to guide eradication planning. Culling decisions should consider genetic value as well as disease status.

Commercial range flocks: Handling facilities may be limited, making individual treatment difficult. Group footbathing at handling points is the primary treatment method. Culling of severely affected animals is practical. Eradication is difficult in open range systems where animals cannot be easily gathered.

Environmental Management Decision Points

Environmental conditions directly affect foot rot transmission and treatment success. The following decision points help veterinarians advise producers on environmental management.

Decision point 1: Pasture management

• If pastures are wet and muddy, recommend moving animals to drier ground or using sacrifice paddocks.
• If pastures are dry, foot rot transmission decreases naturally. Use this period for intensive treatment and eradication efforts.
• Rest pastures for 2 to 4 weeks after removing infected animals to allow Dichelobacter nodosus to die off.

Decision point 2: Laneway and yard management

• If laneways are muddy, recommend improving drainage or using alternative routes.
• If handling yards are muddy, clean and disinfect between groups of animals.
• Place footbaths at the entrance and exit of handling facilities.

Decision point 3: Housing and bedding

• If animals are housed, provide deep, dry bedding and clean regularly.
• If bedding becomes wet and contaminated, remove and replace immediately.
• Maintain adequate ventilation to reduce humidity.

Economic Decision Framework for Culling

Culling decisions require balancing the cost of continued treatment against the value of the animal. The following framework helps veterinarians guide producers.

Cost of continued treatment per animal per year:

• Hoof trimming labor: 5 to 10 minutes per animal at the farm labor rate
• Topical antibiotic spray: cost per treatment multiplied by number of treatments per year
• Systemic antibiotics: cost per dose multiplied by number of doses per year
• Footbath solution: cost per footbath multiplied by number of footbaths per year
• Veterinary time: consultation fees and examination costs

Value of the animal:

• Market value for meat or milk production
• Genetic value for breeding
• Replacement cost for a foot rot-free animal

Culling is economically justified when:

• The cost of treatment exceeds the value of the animal
• The animal has failed to respond to two treatment cycles
• The animal has chronic hoof deformities that predispose to reinfection
• The animal is a source of infection for the rest of the flock

For high-value breeding animals, the decision may be to continue treatment despite high costs. For commercial animals, culling is often the most economical option.

Professional Escalation Criteria for Complex Cases

When standard treatment protocols fail or when the clinical picture is unclear, escalation to a specialist or diagnostic laboratory is indicated. Specific criteria include:

• Flock prevalence of score 3 or higher lesions exceeds 20% despite two cycles of whole-flock treatment
• PCR testing reveals a mixed infection with both virulent and benign strains, complicating eradication planning
• Clinical signs are atypical, suggesting CODD, foot abscess, or other differential diagnoses
• The producer is considering an eradication program and requires a detailed written plan
• Regulatory authorities need to be notified due to notifiable disease status

In these cases, contact a veterinary diagnostic laboratory for guidance on sample collection and testing. The laboratory can provide PCR testing for strain typing and culture for antibiotic sensitivity. Specialists in sheep and goat medicine can assist with developing a customized eradication plan based on the specific flock situation.

Frequently Asked Questions

What is the difference between virulent and benign foot rot?

Virulent foot rot is caused by strains of Dichelobacter nodosus that produce the aprV2 protease, leading to progressive underrunning of the hoof horn and severe lameness. Benign strains produce the aprB2 protease and typically cause only interdigital dermatitis or mild underrunning that resolves under dry conditions. PCR testing can differentiate between the two strain types.

How long does Dichelobacter nodosus survive in the environment?

Dichelobacter nodosus can survive for up to 2 weeks in moist soil, manure, or bedding. Survival is shorter under dry, sunny conditions. The organism does not survive well on pasture during hot, dry weather, which is why foot rot often resolves spontaneously during summer in arid regions.

Can goats get foot rot from sheep?

Yes, goats are susceptible to the same strains of Dichelobacter nodosus that infect sheep. Cross-species transmission can occur when sheep and goats are housed together or share pastures. However, goats are generally less susceptible than sheep and may show milder clinical signs.

How often should footbaths be changed?

Footbath solutions should be changed after every 100 to 200 sheep or when the solution becomes visibly dirty. Contaminated footbaths can spread infection instead of prevent it. The solution should be replaced more frequently in wet weather when feet are muddy.

Is vaccination effective for eradication?

Vaccination reduces the severity of lesions and the duration of infection but does not prevent infection entirely. It is most effective when combined with footbathing, trimming, and culling. Vaccination alone is unlikely to achieve eradication, but it can accelerate progress in flocks with high prevalence.

What is the best time of year to start an eradication program?

The best time to start an eradication program is during dry weather, when environmental survival of Dichelobacter nodosus is lowest. In temperate climates, late spring or early summer is ideal. Starting during wet weather increases the risk of reinfection and treatment failure.

How do I know if eradication is successful?

Eradication is considered successful when PCR testing of a representative sample of the flock (e.g., 30 to 60 animals) is negative for Dichelobacter nodosus. Clinical examination should show no animals with active lesions. Follow-up testing at 6 and 12 months is recommended to confirm that the flock remains free of infection.

What should I do if foot rot returns after eradication?

If foot rot returns after eradication, investigate the source of reintroduction. Common sources include purchased animals, contaminated equipment, or wildlife. PCR test the affected animals to confirm the strain type and compare it to the original strain. Implement quarantine and biosecurity measures to prevent further spread.

Related Veterinary Guides

• Sheep Foot Health And Lameness Prevention
• Goat Health Management Vaccination Biosecurity Disease Prevention
• Beef Cattle Quarantine Management
• Veterinary Clinical Methods Procedures Surgical Interventions
• Beef Cow Pregnancy Diagnosis Records

References and Further Reading

• www.acvim.org
• Merck Veterinary Manual. Merck Veterinary Manual.
• Animal Health and Welfare. World Organisation for Animal Health.
• Advances in the control of foot rot in sheep.. The Veterinary clinics of North America. Food animal practice, 1990.
• Effects of Topical Treatment of Foot Rot in Sheep Using Ozonated Olive Ointment.. Journal of veterinary research, 2021.
• Foot-rot in sheep.. The Veterinary record, 1967.
• Virulent foot rot in sheep.. The Veterinary record, 1997.
• Foot rot in sheep.. The Veterinary record, 1979.
• Foot rot in sheep.. The Veterinary record, 1979.
• Prevalence of Dichelobacter nodosus in western Austrian sheep flocks: Comparison of bacterial cultures, clinical foot rot and lameness with PCR and analysis of sample pooling for PCR diagnosis. Schweizer Archiv Fur Tierheilkunde, 2024.
• Identification and grouping of Dichelobacter nodosus, using PCR and sequence analysis. Molecular and Cellular Probes, 1999.
• Outbreak of severe foot rot associated with benign dichelobacter nodosus in an alpine ibex colony in the swiss prealps. Schweizer Archiv Fur Tierheilkunde, 2015.
• Elimination of virulent strains (aprV2) of Dichelobacter nodosus from feet of 28 Swiss sheep flocks: A proof of concept study. Veterinary Journal, 2016.

This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.