A 5-year-old neutered male Domestic Shorthair cat is pres...

Thank you for sharing this case. The comprehensive initial findings — the acute onset of pain, corneal cloudiness, a positive fluorescein stain, and particularly the miosis, aqueous flare, and decreased intraocular pressure — provide a very clear picture, and I commend you for your thoroughness. This is precisely the kind of detailed information we need to make an accurate assessment.

The combination of a corneal ulcer with concurrent anterior uveitis (indicated by the miosis, aqueous flare, and crucially, the hypotony or low IOP) is highly significant in a cat. In dogs, we might think about a simple ulcer that triggers a mild uveitis, but in felines, we must immediately consider underlying causes.

Cats do not get spontaneous chronic corneal epithelial defects (SCCEDs) or indolent ulcers like dogs do. When we see a non-healing or complicated corneal ulcer in a cat, especially one accompanied by uveitis, our top differential should always be Feline Herpesvirus-1 (FHV-1) keratitis and uveitis. Other possibilities include a corneal foreign body, trauma, or less commonly, Chlamydophila or Mycoplasma conjunctivitis that has progressed. Systemic diseases causing uveitis can also present this way, but the ulcer points to primary ocular involvement.

Given these findings, here's my recommended approach:

Confirm the Diagnosis:

* FHV-1 PCR: A corneal or conjunctival swab for FHV-1 PCR is highly recommended to confirm our suspicion. This guides specific antiviral therapy.
Conjunctival Cytology: A gentle conjunctival scraping for cytology can help rule out other infectious agents (e.g., Chlamydophila, Mycoplasma*) or eosinophilic keratitis, which sometimes presents with an ulcer.
* Full Ophthalmic Examination of the Fellow Eye (OD): Always check the other eye for subtle signs, even if currently asymptomatic.
Schirmer Tear Test (STT): While less standardized in cats, obtaining baseline STT measurements in both eyes before* any other drops are instilled is still good practice.

Immediate Therapeutic Plan:

* Topical Antibiotic: To prevent secondary bacterial infection of the ulcer. I recommend ofloxacin 0.3% drops applied QID (up to q1h if any sign of melting or worsening).
* Topical Cycloplegic/Mydriatic: For the pain associated with uveitis and to prevent posterior synechiae. Use atropine 1% drops BID-TID initially, then taper as the pupil dilates. Warn the owner about potential salivation due to the bitter taste, which is common in cats after atropine administration.
* Systemic Antiviral (if FHV-1 suspected): If FHV-1 is your strong suspicion (which it should be), begin famciclovir 90 mg/kg PO BID. This is crucial for managing the viral component.
* Systemic Anti-inflammatory (for uveitis): Since there is a positive fluorescein stain, topical corticosteroids (e.g., prednisolone acetate ophthalmic 1%) are absolutely contraindicated. Steroids inhibit epithelial healing, potentiate collagenase activity, and can quickly convert a simple ulcer into a melting ulcer and perforation. Instead, consider a systemic NSAID like meloxicam (if renal function is normal and the cat is hydrated) for pain and inflammation. For now, the atropine will help significantly with uveitic pain.
* E-collar: Mandatory to prevent self-trauma and protect the healing cornea.
* Artificial Tears: Can be used frequently (e.g., q4-6h) to provide lubrication and comfort, especially in between medicated drops.

Monitoring and Re-evaluation:

* Recheck this patient in 24-48 hours to assess ulcer healing (fluorescein stain), IOP, and uveitis resolution.
* Continue to monitor for progression of the ulcer or signs of stromal melting, which would necessitate more aggressive intervention (e.g., topical serum, referral for surgery).

This is a serious presentation, and your prompt attention is critical. The combination of ulcer and uveitis in a cat is a red flag for FHV-1, and aggressive, appropriate treatment is key to preserving vision and comfort. Remember, never use topical corticosteroids on an eye with a positive fluorescein stain.