Actinomycosis (Lumpy Jaw) in Cattle: Actinomyces bovis Infection and Wooden Tongue

Introduction

Actinomycosis, commonly known as lumpy jaw, is a chronic, suppurative, and granulomatous disease of cattle caused primarily by the bacterium Actinomyces bovis. The condition is characterized by pyogranulomatous inflammation of the mandibular and maxillary bones, leading to progressive swelling, fistulous tract formation, and eventual structural deformation. A clinically and etiologically distinct but often conflated entity is wooden tongue, or actinobacillosis, caused by Actinobacillus lignieresii. These two infections share overlapping clinical presentations in the oropharyngeal region but differ in their primary tissue tropism: A. bovis targets bone, whereas A. lignieresii targets soft tissues of the tongue and lymphatics [1, 2]. This article provides a detailed reference on Actinomyces bovis actinomycosis lumpy jaw cattle wooden tongue, incorporating the latest histopathological, microbiological, and therapeutic evidence from the veterinary literature.

Etiology and Pathogen Biology

Actinomyces bovis is a Gram-positive, non-acid-fast, non-spore-forming, filamentous, branching rod that is facultatively anaerobic to strictly anaerobic, depending on the strain. The organism is part of the normal oral microbiota of cattle and resides in the gingival crevices, tonsillar crypts, and dental plaques. Disease ensues when the mucosal barrier is breached, typically through penetrating wounds from coarse feed, sharp plant awns, dental procedures, or eruption of cheek teeth. The organism invades adjacent periosteum and bone, inciting a chronic pyogranulomatous response.

In contrast, wooden tongue is caused by Actinobacillus lignieresii, a Gram-negative, non-motile, facultatively anaerobic coccobacillus that also resides in the bovine oral cavity. A. lignieresii preferentially infects soft tissues: the tongue, pharynx, and regional lymph nodes, producing a hard, fibrotic lingual swelling (wooden tongue) that can impair prehension and swallowing.

The distinction between lumpy jaw and wooden tongue is clinically and therapeutically important because antimicrobial susceptibility patterns and tissue penetration differ. Co-infections or sequential infections with both organisms have been documented [2, 3].

Epidemiology and Risk Factors

Actinomycosis is a sporadic, non-contagious disease with a worldwide distribution. It occurs most frequently in cattle older than two years, although cases in younger animals have been described [1]. No breed or sex predilection has been consistently reported.

Predisposing factors include:

• Feeding of coarse, fibrous roughage (e.g., straw, stubble, hay containing foxtail or burrs)
• Dental abnormalities or recent tooth eruption
• Poor oral hygiene and concurrent periodontal disease
• Mucosal trauma from brisket tags, nose rings, or improper intubation

Actinobacillus lignieresii infection is similarly sporadic but can occasionally appear as herd outbreaks, particularly when a common feed source is contaminated with abrasive plant material [4].

Clinical Signs and Pathogenesis

Lumpy Jaw (Actinomyces bovis)

The incubation period is weeks to months. The earliest sign is a firm, painless swelling on the mandible or maxilla, typically at the level of the premolars or molars. Over time, the swelling enlarges, becomes warm, and develops multiple draining sinus tracts that discharge a thick, yellow, granular pus containing characteristic sulfur granules (microscopic bacterial colonies). The overlying skin becomes adherent, alopecic, and may ulcerate.

Advanced disease leads to:

• Dysphagia and weight loss
• Dental loosening and malocclusion
• Osteomyelitis and pathological fracture of the mandible
• Secondary bacterial infection of draining tracts (often with Trueperella pyogenes or anaerobic cocci)
• Respiratory difficulty if the lesion compresses the nasal passages

Systemic signs such as fever and inappetence are usually absent unless secondary infection is severe.

Wooden Tongue (Actinobacillus lignieresii)

The hallmark of wooden tongue is a firm, non-painful, gradually enlarging lingual mass that causes protrusion of the tongue, drooling, and difficulty prehending food. The tongue becomes hard and wooden to palpation. Alternatively, the infection can localize to the submandibular or retropharyngeal lymph nodes, producing abscesses that can fistulate. In some cases, atypical presentations involve the hind limbs or lungs [4, 3].

Pathology and Histopathology

Grossly, lumpy jaw lesions consist of a central zone of purulent, caseous necrosis surrounded by dense fibrous connective tissue. The bone shows rarefying osteomyelitis with periosteal new bone formation. Within the pus, pale yellow to white sulfur granules (1–3 mm) are visible.

Histopathological examination reveals pyogranulomatous inflammation with central aggregates of neutrophils and eosinophilic material (Splendore-Hoeppli phenomenon), surrounded by macrophages, multinucleated giant cells, lymphocytes, and plasma cells. Gram staining of sulfur granules demonstrates Gram-positive filamentous branching rods radiating peripherally (the "club" or "rosette" arrangement). Immunohistochemical studies have demonstrated the presence of immunoglobulins within the granulomatous lesions, indicating a strong humoral component to the host immune response [5].

In goats, a similar mandibular pyogranulomatous osteomyelitis has been described, with identical histomorphology, confirming the cross-species pathogenicity of the Actinomyces group [6].

In Actinobacillus lignieresii infections, the tissue reaction is similar but occurs in soft tissues. Granulomas with central necrosis and sulfur granules are observed, though the causative organism is Gram-negative and can be differentiated by culture or PCR [2, 3].

Diagnostic Approaches

A definitive diagnosis of Actinomyces bovis actinomycosis lumpy jaw cattle wooden tongue requires a combination of clinical, cytological, microbiological, and molecular methods.

Clinical and Imaging Diagnosis

• Palpation of firm mandibular swelling with draining sinuses.
• Radiography: reveals osteolysis, periosteal reaction, and sequestra.
• Ultrasound: can delineate fluid-filled pockets and guide aspiration.

Cytology and Histopathology

• Fine-needle aspiration of pus or biopsy of granulomatous tissue.
• Identification of sulfur granules on gross examination.
• Gram stain: Gram-positive filamentous rods.
• Histopathology: pyogranulomatous inflammation with club colonies.

Microbiological Culture

• Anaerobic culture on brain heart infusion agar supplemented with sheep blood.
• Colonies appear after 48–72 hours as white, rough, or molar-tooth shaped.
• Biochemical identification traditionally relied on fermentation patterns; now MALDI-TOF MS is replacing conventional methods.

Molecular Diagnostics

• PCR targeting 16S rRNA gene sequences specific to Actinomyces bovis or Actinobacillus lignieresii.
• High-throughput sequencing can identify mixed infections.

Differential Diagnoses

• Wooden tongue (A. lignieresii) – primarily lingual or nodal involvement.
• Mandibular abscess (Trueperella pyogenes, Fusobacterium necrophorum).
• Osteosarcoma – rare, does not produce sulfur granules.
• Tuberculosis – caseating granulomas but acid-fast positive.
• Neoplasia – histopathology confirms.

flowchart TD
    A[Clinical suspicion: mandibular swelling or lingual hardness], > B{Examine oral cavity and palpate}
    B, > C[Bone involvement?]
    C, >|Yes| D[Radiography of mandible/maxilla]
    D, > E[Osteolysis + periosteal reaction]
    E, > F[Fine-needle aspiration or biopsy]
    F, > G[Sulfur granules present?]
    G, >|Yes| H[Gram stain: Gram-positive filaments]
    H, > I[Anaerobic culture + PCR for A. bovis]
    G, >|No| J[Consider other causes: abscess, neoplasia]
    C, >|No| K[Lingual or nodal swelling?]
    K, > L[FNA or biopsy of tongue/lymph node]
    L, > M[Gram-negative coccobacilli]
    M, > N[Aerobic culture + PCR for A. lignieresii]
    I, > O[Confirmed lumpy jaw]
    N, > O2[Confirmed wooden tongue]
    O, > P[Start antimicrobial therapy based on susceptibility]
    O2, > P[Start antimicrobial therapy based on susceptibility]

Treatment and Therapeutic Strategies

Antimicrobial Therapy

The cornerstones of medical treatment for lumpy jaw are long-term, high-dose antimicrobials. Actinomyces bovis is susceptible to penicillins, tetracyclines, clindamycin, and erythromycin. Resistance to aminoglycosides is common.

Standard protocols include:

• Sodium iodide or potassium iodide intravenous or oral therapy, often combined with mercuric nitrate historically [7]. Iodide therapy is thought to enhance granuloma softening and antimicrobial penetration, although its use has declined due to the availability of more effective antibiotics.
• Procaine penicillin G (20,000–40,000 IU/kg intramuscularly daily for 2–4 weeks) or long-acting amoxicillin.
• Tetracyclines (e.g., oxytetracycline 10–20 mg/kg intravenously or intramuscularly for 5–7 days, then oral doxycycline if tolerated).
• Surgical debridement of necrotic bone and drainage of abscesses is often necessary in advanced cases to reduce bacterial load and allow antibiotic penetration.

For wooden tongue, Actinobacillus lignieresii is susceptible to penicillin, tetracyclines, and cephalosporins. Iodide therapy is also historically reported to be beneficial. Early cases may respond to antimicrobials alone; chronic cases require surgical excision of granulomatous tissue.

Surgical Intervention

Surgical curettage, sequestrectomy, and establishment of drainage tracts are indicated when:

• Medical therapy fails after 7–10 days.
• Large sequestra are present on radiography.
• Mechanical interference with feeding or breathing occurs.
• Secondary infection with suppurative bacteria is unresponsive.

En bloc resection of the affected mandibular segment is rarely performed due to poor cosmetic and functional outcomes.

Prognosis

With early diagnosis and aggressive combination therapy, the prognosis for lumpy jaw is fair to good. Chronic, extensive lesions with bone lysis carry a guarded prognosis. Wooden tongue generally responds well to treatment if initiated before extensive fibrosis develops.

Control and Prevention

Because Actinomyces bovis and Actinobacillus lignieresii are commensal organisms, elimination from the herd is not feasible. Prevention focuses on reducing mucosal injury:

• Avoid feeding coarse or contaminated roughage.
• Inspect feed for sharp plant material.
• Maintain proper dental health and address dental overgrowth.
• Disinfect any oral instrumentation between animals.
• Quarantine and treat affected animals promptly to minimize environmental contamination with purulent material.

No commercial vaccines are available. Herd-level biosecurity and hygiene measures are the only practical control strategies.

Actinomycosis should be distinguished from other chronic granulomatous conditions such as Mycoplasma bovis in Feedlot Cattle which can also cause abscessation but lacks sulfur granules, and Bovine Mastitis Caused by Staphylococcus aureus which involves a different tissue system.

References

[1] Christener N, Van der Vekens E, Gurtner C, et al. Actinomycosis in cattle – Five clinical cases. Schweiz Arch Tierheilkd. 2026. URL: https://pubmed.ncbi.nlm.nih.gov/42226539/

[2] Salvaggio A, Giunta RP, Percipalle M, et al. Infection Due to Actinobacillus lignieresii in Cattle with Brain and Ocular Involvement: Histological and Microbiological Features. Vet Sci. 2023. URL: https://pubmed.ncbi.nlm.nih.gov/37235394/

[3] Caffarena RD, Rabaza A, Casaux L, et al. Natural lymphatic ("atypical") actinobacillosis in cattle caused by Actinobacillus lignieresii. J Vet Diagn Invest. 2018. URL: https://pubmed.ncbi.nlm.nih.gov/29202671/

[4] Relun A, Cesbron N, Bourdeau P, et al. Atypical actinobacillosis affecting hind limbs and lungs in a single beef cattle herd. J Vet Intern Med. 2019. URL: https://pubmed.ncbi.nlm.nih.gov/30548325/

[5] Momotani E, Kubo M, Ishikawa Y, et al. Immunohistochemical localization of immunoglobulins in bovine granulomatous lesions. J Comp Pathol. 1989. URL: https://pubmed.ncbi.nlm.nih.gov/2715395/

[6] Seifi HA, Saifzadeh S, Farshid AA, et al. Mandibular pyogranulomatous osteomyelitis in a Sannen goat. J Vet Med A Physiol Pathol Clin Med. 2003. URL: https://pubmed.ncbi.nlm.nih.gov/12948160/

[7] Nusbaum SR. A practitioner's experience with intravenous sodium iodide-mercuric nitrate therapy in Actinomyces bovis infection. Vet Med Small Anim Clin. 1965. URL: https://pubmed.ncbi.nlm.nih.gov/14335040/

[8] Zoman KA, Alshunaifi K, Al-Mutairi M, et al. Evaluation of oral lesions and dental health in HIV-positive Saudi patients. Saudi Dent J. 2024. URL: https://pubmed.ncbi.nlm.nih.gov/40952863/