What is Dr. Zubair Khalid's research focus?

Dr. Zubair Khalid specializes in molecular virology, mRNA vaccine development, and computational biology, with a focus on avian pathogens like IBDV and Avian Reovirus.

Where is Dr. Zubair Khalid currently working?

Dr. Zubair Khalid is a Postdoctoral Research Associate at the University of Maryland (UMD), specifically within the Department of Animal and Avian Sciences.

Ruminant Ocular Diseases: Diagnosis and Treatment

This article provides diagnostic and treatment guidance for common eye conditions in cattle, sheep, and goats, focusing on infectious keratoconjunctivitis, trauma, and neoplasia. The content is intended for veterinarians managing ocular disease in ruminant practice. Clinical decisions must be based on individual animal examination, herd history, and applicable regulations.

At a Glance

Condition	Primary Species	Key Clinical Signs	Diagnostic Approach	First-Line Treatment Considerations
Infectious bovine keratoconjunctivitis (IBK)	Cattle	Conjunctivitis, corneal opacity, ulceration, blepharospasm, photophobia	Clinical examination, culture and sensitivity, PCR	Topical antibiotics, subconjunctival injection, NSAIDs, eye patch or third eyelid flap for advanced cases
Infectious keratoconjunctivitis (IKC)	Sheep, goats	Conjunctivitis, keratitis, corneal edema, serous to mucopurulent discharge	Clinical examination, PCR, serology (Chlamydia, Mycoplasma)	Topical tetracycline or oxytetracycline, systemic oxytetracycline, supportive care
Ocular squamous cell carcinoma (OSCC)	Cattle (especially Hereford, Holstein)	Raised, ulcerated, or proliferative mass on cornea, conjunctiva, or eyelid	Clinical examination, biopsy, cytology	Surgical excision, cryotherapy, hyperthermia, radiation therapy, immunotherapy
Trauma	All ruminants	Corneal laceration, perforation, hyphema, lens luxation, proptosis	Clinical examination, fluorescein stain, slit-lamp exam, ultrasound	Medical management for minor injuries, surgical repair for severe cases, enucleation for non-salvageable eyes

Infectious Keratoconjunctivitis in Cattle

Etiology and Pathogenesis

Infectious bovine keratoconjunctivitis (IBK), commonly called pinkeye, is a highly contagious ocular disease primarily caused by Moraxella bovis. Other bacteria, including Moraxella bovoculi, Mycoplasma species, and viruses such as infectious bovine rhinotracheitis (IBR) virus, can contribute to or complicate the condition. The Perceptions and practices of Australian cattle farmers for the treatment of pinkeye (infectious bovine keratoconjunctivitis) study highlights the importance of understanding farmer treatment approaches for effective disease management (Preventive Veterinary Medicine, 2021). The Current incidence, treatment costs and seasonality of pinkeye in Australian cattle estimated from sales of three popular medications study provides data on the economic impact and seasonal patterns of the disease (Preventive Veterinary Medicine, 2021).

Moraxella bovis produces a hemolysin and a pilus that facilitate adherence to corneal epithelium. Ultraviolet light, dust, flies, and plant awns act as predisposing factors by damaging the corneal surface and creating portals of entry for bacteria. The incubation period is typically 2 to 3 days. Clinical signs progress from conjunctivitis and lacrimation to corneal edema, ulceration, and in severe cases, corneal perforation and blindness.

Clinical Signs and Staging

Clinical staging of IBK aids in treatment decisions and prognosis. Stage I is characterized by conjunctivitis, epiphora, and mild corneal edema. Stage II involves a central corneal ulcer with progressive edema and neovascularization. Stage III shows a larger ulcer with stromal loss, keratomalacia, and possible iris prolapse. Stage IV is corneal perforation with iris prolapse or endophthalmitis.

Diagnosis

Diagnosis is based on clinical examination. Fluorescein staining confirms corneal ulceration. Conjunctival or corneal swabs for bacterial culture and sensitivity are recommended, especially in treatment-refractory cases or outbreaks. PCR testing can identify Moraxella species and other pathogens. Differential diagnoses include IBR keratoconjunctivitis, trauma, foreign bodies, and ocular squamous cell carcinoma.

Treatment

Treatment aims to eliminate infection, reduce inflammation, and promote corneal healing. Topical antibiotics such as oxytetracycline, gentamicin, or ciprofloxacin are commonly used. Subconjunctival injection of antibiotics provides sustained local concentrations. Systemic NSAIDs reduce pain and inflammation. The Treatment for pinkeye in cattle study discusses various treatment approaches (Modern Veterinary Practice, 1976). The An effective single treatment for pinkeye in cattle and non-specific keratitis in horses study describes a single-treatment protocol (Veterinary Medicine, Small Animal Clinician, 1970).

For advanced cases (Stage III and IV), surgical intervention may be necessary. The Surgical treatment of advanced pinkeye in cattle study outlines surgical options (Veterinary Medicine, Small Animal Clinician, 1974). Third eyelid flaps, conjunctival grafts, or tarsorrhaphy can protect the cornea and promote healing. Enucleation is indicated for non-salvageable eyes.

Prevention and Control

Control measures include fly control, reducing dust and UV exposure, isolating affected animals, and maintaining good hygiene. Vaccination against Moraxella bovis is available but efficacy varies. The A randomised control trial to evaluate the effectiveness of a commercial vaccine for pinkeye in Australian beef cattle study evaluates vaccine efficacy (Preventive Veterinary Medicine, 2023). Biosecurity protocols should be implemented to prevent introduction and spread of IBK.

Infectious Keratoconjunctivitis in Sheep and Goats

Etiology and Pathogenesis

Infectious keratoconjunctivitis (IKC) in sheep and goats is caused by Chlamydia pecorum and Mycoplasma conjunctivae. Other pathogens, including Mycoplasma species, Moraxella species, and Branhamella ovis, can be involved. The Mycoplasmal syndrome in goats study discusses mycoplasmal infections in goats (Point Veterinaire, 2003). The Clinical management of stage I pinkeye with concurrent pneumonic pasteurellosis in a goat: A case report describes a clinical case of pinkeye in a goat (Journal of Advanced Veterinary and Animal Research, 2017).

Transmission occurs through direct contact, fomites, and flies. Predisposing factors include overcrowding, poor ventilation, and concurrent diseases. The incubation period is 2 to 7 days. Clinical signs include conjunctivitis, keratitis, corneal edema, and serous to mucopurulent discharge. Severe cases can progress to corneal ulceration, perforation, and blindness.

Diagnosis

Diagnosis is based on clinical signs and confirmed by PCR or serology. Conjunctival swabs for PCR can identify Chlamydia and Mycoplasma species. Differential diagnoses include trauma, foreign bodies, and other infectious causes.

Treatment

Topical tetracycline or oxytetracycline ointment is the mainstay of treatment. Systemic oxytetracycline is indicated for severe cases or when multiple animals are affected. Supportive care includes NSAIDs for pain and inflammation, and eye patches or third eyelid flaps for corneal protection. The Clinical management of stage I pinkeye with concurrent pneumonic pasteurellosis in a goat: A case report describes treatment of pinkeye in a goat (Journal of Advanced Veterinary and Animal Research, 2017).

Prevention and Control

Control measures include isolating affected animals, improving ventilation, reducing stocking density, and controlling flies. Biosecurity protocols should be implemented. Vaccination is not routinely available for IKC in sheep and goats.

Ocular Squamous Cell Carcinoma in Cattle

Etiology and Pathogenesis

Ocular squamous cell carcinoma (OSCC) is a common neoplasm of cattle, particularly affecting breeds with non-pigmented eyelids and corneas such as Hereford, Holstein, and Simmental. Ultraviolet light exposure is a major risk factor. The tumor arises from the corneal or conjunctival epithelium and can be locally invasive. Metastasis to regional lymph nodes and lungs can occur.

Clinical Signs

OSCC presents as a raised, ulcerated, or proliferative mass on the cornea, conjunctiva, or eyelid. Lesions may be single or multiple. Clinical signs include blepharospasm, epiphora, and secondary conjunctivitis. Advanced lesions can invade the orbit and cause exophthalmos.

Diagnosis

Diagnosis is based on clinical examination and confirmed by biopsy and histopathology. Cytology of impression smears can be helpful. Differential diagnoses include papilloma, granulation tissue, and other neoplasms.

Treatment

Treatment options include surgical excision, cryotherapy, hyperthermia, radiation therapy, and immunotherapy. Surgical excision with wide margins is the treatment of choice for localized lesions. Cryotherapy and hyperthermia are effective for small lesions. Radiation therapy is used for superficial lesions. Immunotherapy with bacillus Calmette-Guerin (BCG) or other immunomodulators has been described. Enucleation or orbitectomy is indicated for advanced or recurrent lesions.

Prevention

Prevention focuses on reducing UV exposure, providing shade, and selecting for pigmented eyelids. Regular examination of at-risk animals allows early detection and treatment.

Trauma

Etiology and Pathogenesis

Ocular trauma in ruminants can result from foreign bodies, plant awns, horns, fences, and handling equipment. Corneal lacerations, perforations, hyphema, lens luxation, and proptosis can occur. Secondary infection and uveitis are common complications.

Clinical Signs

Clinical signs include blepharospasm, epiphora, conjunctival hyperemia, corneal edema, and hyphema. Corneal lacerations may be linear or irregular. Perforation can lead to iris prolapse, lens luxation, and endophthalmitis.

Diagnosis

Diagnosis is based on history and clinical examination. Fluorescein staining confirms corneal ulceration. Slit-lamp examination and ocular ultrasound are useful for assessing intraocular structures.

Treatment

Minor corneal abrasions and ulcers are treated with topical antibiotics and NSAIDs. Corneal lacerations require surgical repair with absorbable sutures. Perforations with iris prolapse require surgical debridement and repair. Hyphema is managed with rest, topical corticosteroids, and NSAIDs. Lens luxation may require lensectomy. Proptosis is an emergency requiring immediate reduction and tarsorrhaphy. Enucleation is indicated for non-salvageable eyes.

Diagnostic Approach

History and Signalment

A thorough history includes onset and duration of clinical signs, number of animals affected, recent introductions, vaccination status, and management practices. Signalment includes species, breed, age, and sex.

Physical Examination

A complete physical examination is performed, including assessment of body condition, hydration, and concurrent diseases. Ocular examination includes assessment of vision, pupillary light reflexes, and intraocular pressure. The adnexa, conjunctiva, cornea, anterior chamber, lens, and fundus are examined.

Diagnostic Tests

Fluorescein staining is used to detect corneal ulcers. Schirmer tear test assesses tear production. Intraocular pressure is measured with a tonometer. Conjunctival and corneal swabs are submitted for bacterial culture and sensitivity, PCR, or serology. Biopsy and histopathology are indicated for suspected neoplasia.

Treatment Protocols

Medical Management

Topical antibiotics are administered 4 to 6 times daily. Subconjunctival injections provide sustained local concentrations. Systemic antibiotics are indicated for severe cases or when multiple animals are affected. NSAIDs reduce pain and inflammation. Atropine is used for uveitis to reduce pain and prevent synechiae.

Surgical Management

Third eyelid flaps, conjunctival grafts, and tarsorrhaphy protect the cornea and promote healing. Corneal lacerations are repaired with absorbable sutures. Enucleation is indicated for non-salvageable eyes.

Supportive Care

Eye patches or Elizabethan collars prevent self-trauma. Fly control reduces irritation and secondary infection. Nutritional support and stress reduction aid recovery.

Prevention and Biosecurity

Vaccination

Vaccination against Moraxella bovis is available for cattle. Efficacy varies, and booster doses are required. The A randomised control trial to evaluate the effectiveness of a commercial vaccine for pinkeye in Australian beef cattle study evaluates vaccine efficacy (Preventive Veterinary Medicine, 2023).

Fly Control

Fly control reduces transmission of IBK and IKC. Insecticides, fly traps, and biological control methods are used. Reducing breeding sites and maintaining clean environments are important.

Environmental Management

Reducing dust and UV exposure by providing shade and using dust suppressants can reduce the incidence of IBK. Good ventilation and reducing stocking density in sheep and goats reduce the risk of IKC.

Biosecurity

Isolating affected animals, quarantining new introductions, and implementing hygiene protocols prevent introduction and spread of ocular diseases.

Common Failure Patterns

Treatment Failure

Treatment failure can result from inappropriate antibiotic selection, inadequate dosing or duration, concurrent infections, or poor compliance. Culture and sensitivity testing is recommended for refractory cases.

Recurrence

Recurrence of IBK or IKC can occur due to persistent infection, re-exposure, or incomplete resolution. Control measures should be reviewed and intensified.

Complications

Complications include corneal perforation, endophthalmitis, glaucoma, and blindness. Early recognition and appropriate management reduce the risk of complications.

Limitations and Professional Escalation

Limitations of Field Diagnosis

Field diagnosis of ocular diseases is based on clinical signs, which can be similar across different etiologies. Laboratory confirmation is necessary for definitive diagnosis.

When to Refer

Referral to a veterinary ophthalmologist is indicated for complex cases, such as corneal perforations, lens luxation, glaucoma, or suspected intraocular neoplasia. Advanced diagnostic imaging and surgical techniques may be required.

Regulatory Considerations

Use of antibiotics in food animals must comply with withdrawal periods and regulations. The World Organisation for Animal Health (WOAH) provides guidelines on animal health and welfare (World Organisation for Animal Health, Animal Health and Welfare). The Merck Veterinary Manual provides information on ocular diseases in ruminants (Merck Veterinary Manual). The American College of Veterinary Internal Medicine (ACVIM) provides resources on veterinary internal medicine (American College of Veterinary Internal Medicine).

Practical Decision Framework for Ruminant Ocular Disease Management

Clinical Staging and Treatment Decision Matrix

A systematic decision framework helps veterinarians match treatment intensity to disease severity while avoiding unnecessary interventions or delays. The following matrix integrates clinical staging with treatment protocols for infectious keratoconjunctivitis in cattle, sheep, and goats.

Stage I (Mild Disease) Clinical findings: Conjunctival hyperemia, epiphora, mild corneal edema, no visible ulcer. Fluorescein stain negative or minimal uptake. Treatment protocol: Topical broad-spectrum antibiotic ointment (oxytetracycline or gentamicin) applied twice daily for 5 to 7 days. Topical NSAID (flunixin meglumine or ketoprofen) once daily for 3 days. No eye patch required unless photophobia is severe. Re-examine at day 3 and day 7. If no improvement by day 3, progress to Stage II protocol.

Stage II (Moderate Disease) Clinical findings: Central corneal ulcer less than 5 mm diameter, moderate corneal edema, neovascularization beginning at limbus. Fluorescein stain positive with defined ulcer margins. Treatment protocol: Topical antibiotic four times daily for 7 to 10 days. Subconjunctival antibiotic injection (gentamicin 50 mg or oxytetracycline 100 mg) at initial examination. Systemic NSAID (flunixin meglumine 1.1 mg/kg IV or IM) once daily for 3 days. Eye patch or temporary tarsorrhaphy for corneal protection. Re-examine at day 3, day 7, and day 14. If ulcer enlarges or corneal edema increases by day 3, escalate to Stage III protocol.

Stage III (Severe Disease) Clinical findings: Corneal ulcer greater than 5 mm diameter, deep stromal loss, keratomalacia (corneal melting), possible iris prolapse. Fluorescein stain positive with irregular margins. Treatment protocol: Topical antibiotic six times daily for 14 to 21 days. Subconjunctival antibiotic injection at initial examination and repeat at day 3 if needed. Systemic NSAID for 5 to 7 days. Systemic antibiotic (oxytetracycline 20 mg/kg IM every 48 hours or ceftiofur 2.2 mg/kg IM daily) for 7 to 10 days. Third eyelid flap or conjunctival graft for corneal coverage. Atropine 1% topical once daily for uveitis. Re-examine at day 1, day 3, day 7, and day 14. If corneal perforation occurs or iris prolapse develops, proceed to Stage IV protocol.

Stage IV (End-Stage Disease) Clinical findings: Corneal perforation, iris prolapse, endophthalmitis, hypopyon, glaucoma. Vision loss likely. Treatment protocol: Surgical repair under general anesthesia or sedation with local block. Options include conjunctival graft, corneal suture repair, or enucleation. Systemic antibiotics for 10 to 14 days. Systemic NSAIDs for 5 to 7 days. Post-operative care includes topical antibiotics and atropine. Enucleation is indicated if the eye is non-salvageable, painful, or infected. Refer to veterinary ophthalmologist if available.

Treatment Selection Criteria for Infectious Keratoconjunctivitis

The choice between topical, subconjunctival, and systemic treatment depends on disease severity, number of animals affected, and practical constraints. The Treatment for pinkeye in cattle study (Modern Veterinary Practice, 1976) and the An effective single treatment for pinkeye in cattle and non-specific keratitis in horses study (Veterinary Medicine, Small Animal Clinician, 1970) provide historical context for treatment approaches.

Topical treatment alone is appropriate for Stage I disease in individual animals. It requires frequent handling, which may be stressful and impractical for large herds. Compliance is a major limitation, as owners may not apply medication at the required frequency.

Subconjunctival injection provides sustained antibiotic levels for 48 to 72 hours and is suitable for Stage II disease or when topical treatment is impractical. It requires proper restraint and technique to avoid intraocular injection. The An effective single treatment for pinkeye in cattle and non-specific keratitis in horses study describes a single subconjunctival treatment protocol (Veterinary Medicine, Small Animal Clinician, 1970).

Systemic antibiotics are indicated for Stage III and IV disease, when multiple animals are affected, or when concurrent infections are present. The Clinical management of stage I pinkeye with concurrent pneumonic pasteurellosis in a goat: A case report describes systemic treatment in a goat with concurrent respiratory disease (Journal of Advanced Veterinary and Animal Research, 2017). Withdrawal periods must be observed for meat and milk.

Combination therapy (topical plus subconjunctival plus systemic) is recommended for Stage III and IV disease. The Surgical treatment of advanced pinkeye in cattle study describes surgical options for advanced cases (Veterinary Medicine, Small Animal Clinician, 1974).

Record System for Ocular Disease Management

A standardized record system enables tracking of individual animal response, herd prevalence, and treatment efficacy. The following fields should be recorded for each case:

Animal identification: Ear tag number, breed, age, sex, and location (pen, pasture, barn).

Date of first examination: Record the date when clinical signs were first observed and when treatment was initiated.

Clinical stage: Stage I, II, III, or IV based on the decision matrix above.

Eye affected: Left, right, or both. Record separately for each eye.

Diagnostic tests performed: Fluorescein stain result, culture and sensitivity submission date, PCR test date and results.

Treatment administered: Drug name, dose, route, frequency, and duration. Record batch numbers for antibiotics.

Treatment response: Assess at each re-examination. Categories include: resolved (no clinical signs), improved (reduced ulcer size, less edema), static (no change), worsened (increased ulcer size, perforation).

Complications: Corneal perforation, iris prolapse, endophthalmitis, glaucoma, blindness.

Outcome: Vision preserved, vision lost, enucleation, death.

Withdrawal period: Record the date when withdrawal period ends for meat and milk.

Cost of treatment: Record drug costs, veterinary fees, and labor for economic analysis.

A herd-level record should include total number of cases, number of animals treated, treatment success rate, recurrence rate, and total cost. The Current incidence, treatment costs and seasonality of pinkeye in Australian cattle estimated from sales of three popular medications study provides data on treatment costs and seasonality (Preventive Veterinary Medicine, 2021).

Troubleshooting Treatment Failure

Treatment failure occurs when clinical signs do not improve within 3 to 5 days of initiating therapy. Common causes include:

Inappropriate antibiotic selection: The causative organism may be resistant to the chosen antibiotic. Culture and sensitivity testing is recommended for refractory cases. The Perceptions and practices of Australian cattle farmers for the treatment of pinkeye (infectious bovine keratoconjunctivitis) study highlights that farmer treatment choices may not always align with best practices (Preventive Veterinary Medicine, 2021).

Inadequate dosing or frequency: Topical antibiotics must be applied 4 to 6 times daily for effective corneal concentrations. Subconjunctival injections provide sustained levels but may not be sufficient for severe infections.

Concurrent infections: Mixed infections with Moraxella bovoculi, Mycoplasma species, or IBR virus may require broader-spectrum treatment. The Mycoplasmal syndrome in goats study discusses mycoplasmal infections in goats (Point Veterinaire, 2003).

Poor compliance: Owners may not apply medication as prescribed. Education and demonstration of proper technique are essential.

Corneal sequestrum: A dark, hard plaque of necrotic cornea may form, preventing healing. Surgical debridement is required.

Underlying systemic disease: Concurrent pneumonia, parasitism, or nutritional deficiencies impair immune response and healing. The Clinical management of stage I pinkeye with concurrent pneumonic pasteurellosis in a goat: A case report describes a case with concurrent respiratory disease (Journal of Advanced Veterinary and Animal Research, 2017).

Re-exposure: Affected animals may be re-infected from untreated herdmates or environmental sources. Isolation and biosecurity measures must be reviewed.

Comparison of Treatment Approaches for Infectious Keratoconjunctivitis

Treatment Approach	Advantages	Disadvantages	Indications
Topical antibiotics alone	Low cost, easy to administer, no withdrawal period for most drugs	Requires frequent handling, poor compliance, limited corneal penetration	Stage I disease, individual animals
Subconjunctival injection	Sustained local levels, single administration, good corneal penetration	Requires restraint and skill, risk of intraocular injection, local tissue reaction	Stage II disease, when topical treatment is impractical
Systemic antibiotics	Treats concurrent infections, good for multiple animals, reaches deep tissues	Withdrawal periods, cost, potential for injection site reactions	Stage III and IV disease, multiple animals affected, concurrent infections
Third eyelid flap	Protects cornea, promotes healing, reduces pain	Requires general anesthesia or heavy sedation, may trap infection, requires suture removal	Stage III disease, corneal ulcer with stromal loss
Conjunctival graft	Provides blood supply and structural support, promotes healing	Requires surgical expertise, general anesthesia, post-operative care	Stage III and IV disease, corneal perforation, descemetocele
Enucleation	Definitive treatment for non-salvageable eyes, eliminates pain and infection	Loss of vision, cosmetic defect, requires general anesthesia	Stage IV disease, endophthalmitis, glaucoma, neoplasia

Practical Implementation Steps for Herd-Level Management

Step 1: Identify affected animals Conduct weekly ocular examinations during peak season (spring to autumn in temperate climates). The Current incidence, treatment costs and seasonality of pinkeye in Australian cattle estimated from sales of three popular medications study identifies seasonal patterns (Preventive Veterinary Medicine, 2021). Examine all animals in affected groups.

Step 2: Isolate affected animals Move affected animals to a separate pen or pasture to reduce transmission. Use dedicated equipment and boots for the isolation area. Maintain isolation for at least 14 days after clinical resolution.

Step 3: Initiate treatment Follow the clinical staging decision matrix to select appropriate treatment. Record all treatments in the record system.

Step 4: Implement environmental controls Reduce dust by sprinkling water on dry lots. Provide shade structures to reduce UV exposure. Implement fly control using insecticide ear tags, pour-ons, or fly traps. The Perceptions and practices of Australian cattle farmers for the treatment of pinkeye (infectious bovine keratoconjunctivitis) study discusses farmer practices for environmental management (Preventive Veterinary Medicine, 2021).

Step 5: Monitor treatment response Re-examine treated animals at the intervals specified in the decision matrix. Record outcomes and adjust treatment as needed.

Step 6: Review and adjust prevention strategies After the outbreak resolves, review the effectiveness of control measures. Consider vaccination for future seasons. The A randomised control trial to evaluate the effectiveness of a commercial vaccine for pinkeye in Australian beef cattle study evaluates vaccine efficacy (Preventive Veterinary Medicine, 2023).

Common Failure Patterns in Ocular Disease Management

Pattern 1: Delayed treatment initiation Farmers may delay treatment until clinical signs are advanced, reducing the chance of successful medical management. Education on early recognition and treatment is essential.

Pattern 2: Inadequate treatment duration Owners may stop treatment once clinical signs improve, leading to relapse. Complete the full course of antibiotics as prescribed.

Pattern 3: Failure to isolate affected animals Continued exposure to infected herdmates or environmental sources leads to reinfection. Isolation is critical for outbreak control.

Pattern 4: Ignoring concurrent diseases Animals with pneumonia, parasitism, or nutritional deficiencies have impaired immune responses. Address concurrent health issues to improve treatment outcomes.

Pattern 5: Overreliance on vaccination Vaccination is a preventive measure, not a treatment. The A randomised control trial to evaluate the effectiveness of a commercial vaccine for pinkeye in Australian beef cattle study indicates variable vaccine efficacy (Preventive Veterinary Medicine, 2023). Vaccination should be part of a comprehensive control program.

Welfare and Safety Context

Ocular diseases cause significant pain and distress in affected animals. Clinical signs include blepharospasm, photophobia, and epiphora, indicating discomfort. Corneal ulcers are painful due to exposure of corneal nerve endings. Advanced disease can lead to blindness, which compromises welfare and productivity.

The World Organisation for Animal Health (WOAH) provides guidelines on animal health and welfare, including disease prevention and control (World Organisation for Animal Health, Animal Health and Welfare). The Merck Veterinary Manual provides information on ocular diseases in ruminants (Merck Veterinary Manual). The American College of Veterinary Internal Medicine (ACVIM) provides resources on veterinary internal medicine (American College of Veterinary Internal Medicine).

Treatment should aim to relieve pain, control infection, and preserve vision. NSAIDs are essential for pain management. Surgical intervention should be considered for non-responsive cases to prevent prolonged suffering. Enucleation is a humane option for non-salvageable eyes.

Professional Escalation Criteria

Refer to a veterinary ophthalmologist or experienced large animal surgeon when:

Corneal perforation with iris prolapse is present
Corneal ulcer does not improve after 7 days of appropriate treatment
Corneal sequestrum develops
Glaucoma is suspected (buphthalmos, elevated intraocular pressure)
Lens luxation or cataract develops
Intraocular neoplasia is suspected
Enucleation is required but the veterinarian lacks experience
Multiple animals in a herd are affected and treatment is failing

Limitations of Field Diagnosis and Treatment

Field diagnosis relies on clinical signs, which can be similar across different etiologies. Laboratory confirmation is necessary for definitive diagnosis, especially in outbreaks or treatment-refractory cases. Culture and sensitivity testing requires 48 to 72 hours for results, during which empirical treatment must be initiated.

Treatment in field conditions is limited by practical constraints, including animal restraint, drug availability, and owner compliance. The Perceptions and practices of Australian cattle farmers for the treatment of pinkeye (infectious bovine keratoconjunctivitis) study highlights that farmer treatment choices may be influenced by cost, convenience, and previous experience (Preventive Veterinary Medicine, 2021).

Withdrawal periods for antibiotics in food animals must be observed. The Current incidence, treatment costs and seasonality of pinkeye in Australian cattle estimated from sales of three popular medications study provides data on treatment costs (Preventive Veterinary Medicine, 2021). Record all treatments and withdrawal dates to ensure food safety compliance.