Case study: The cat with 'sore eyes'

General demeanor, appetite, thirst, and litter box habits: He has been a little quieter than usual at home and has been off his food a little bit, although he is still eating and prefers softer food. There may have been a small amount of weight loss, but he is also "getting older". There is no change in his drinking noted, but she does not know about toileting as he spends a lot of time outdoors. She has noted no vomiting or diarrhea.

History of the problem: Both eyes seemed to become red at roughly the same time. The owner does not think one eye was affected first, although the right eye may look "a bit angrier" today. There is no known trauma. He goes outdoors during the day and occasionally comes home with minor scratches, but no wounds have been noticed recently. There has been no known exposure to irritant chemicals, smoke or sprays. The owner would normally apply ophthalmic drops, but has not as they have run out.

He sneezed several times last week and had a small amount of clear nasal discharge, but this seems to have improved. His breathing has been normal at home. There has been no coughing.

Sight: The owner has not noticed him bumping into furniture or missing jumps. He can find his food fine and move around the house normally.

Preventive care: He is up to date with his flea prevention and deworming and vaccinations. The cat is insured.

Other cats: Two of the other cats are currently well, although the third was in a fight a few days ago and was also due for an appointment which had to be canceled when he ran off this morning.

At this stage, your priority is to decide whether this is simple conjunctivitis/keratitis, or whether there is deeper intraocular disease.

• Vision assessment and PLRs: assess each eye separately using menace response, dazzle reflex and direct/consensual PLRs. Menace can be unreliable in stressed cats, so interpret it alongside the rest of the examination.
• Close anterior segment examination with focal illumination and magnification: look for corneal disease, anterior chamber flare/cells/fibrin, keratic precipitates, iris change, synechiae, pupil shape and lens position.
• Fluorescein staining of both eyes: rule out corneal ulceration before considering topical corticosteroids, and look for subtle epithelial disease that could fit feline herpesvirus.
• Tonometry in both eyes: essential in any painful red eye. Low IOP supports active uveitis; raised IOP changes urgency. If using a Tono-Pen, apply topical local anesthetic immediately beforehand; if using a TONOVET, this is usually not required. Measure IOP before therapeutic mydriatics.
• Fundic examination if the view and patient allow: look for retinal hemorrhage, detachment, chorioretinal lesions or optic nerve changes. Do not use a mydriatic until IOP has been assessed; if miosis limits the view, record the limitation.
• Blood pressure measurement: hypertension is an important mimic or contributor in feline ocular disease, especially if fundic changes, hyphema or visual deficits are present.

Do not dispense topical antibiotics alone. The history still fits a URI flare-up, but photophobia, miosis and systemic findings mean conjunctivitis should not be assumed.

You move the cat to a quieter room and complete a basic ophthalmic assessment.

Systolic blood pressure: 160 mmHg average over 5 Doppler readings.

On closer anterior segment examination, both eyes have moderate conjunctival hyperemia and mild chemosis. There are no signs of distichiasis. The corneas remain clear and there is no fluorescein uptake.

Both pupils are miotic. There is aqueous flare bilaterally, with a small amount of fine fibrin visible ventrally in the anterior chamber of both eyes. This is more obvious in the right eye. There are a few fine keratic precipitates on the ventral corneal endothelium.

The irides look mildly darkened and slightly swollen compared with normal. There is some loss of normal iris surface detail, but no discrete iris mass, obvious iris nodule or gross distortion of the pupil margin. The lens appears in normal position in both eyes.

Fundic examination is possible, although the view is mildly limited by miosis and anterior chamber flare. No retinal detachment, retinal hemorrhage or obvious optic nerve abnormality is seen.

• Bilateral anterior uveitis: aqueous flare, fine fibrin, miosis, low intraocular pressures and subtle iris changes in both eyes.
• Bilateral conjunctival hyperemia and mild chemosis with watery to mucoid ocular discharge; fluorescein negative in both eyes.
• Photophobia/ocular discomfort: squinting, reluctance to face bright light and face rubbing.
• Reduced or inconsistent menace responses, with dazzle reflexes present and no owner-reported blindness.
• Mild upper respiratory signs: recent sneezing, mild serous nasal discharge and normal breathing/thoracic auscultation.
• Weight loss and reduced appetite: 4.1 kg today, previously 4.5 kg eight months ago; eating less and favoring softer food.
• Dental disease: moderate dental calculus and gingivitis, with no obvious oral mass or marked focal oral pain.
• Peripheral lymphadenopathy: submandibular nodes moderately enlarged and prescapular nodes mildly enlarged; non-painful, mobile and non-fluctuant.
• Borderline/high-normal systolic blood pressure: average 160 mmHg over five Doppler readings, with no retinal hemorrhage or detachment seen.

 At this point, FHV-1 recrudescence remains plausible for the owner-noticed red eyes, discharge and sneezing, but it does not explain the full problem list. Priorities to carry forward include FeLV/FIV-associated disease, FIP, toxoplasmosis, multicentric lymphoma with ocular involvement, systemic hypertension as a mimic or contributor, and FHV-1 or other infectious conjunctivitis as a concurrent or misleading surface problem.  

This is no longer a routine URI or conjunctivitis case. The cat has bilateral anterior uveitis, and the priority is to treat the painful intraocular inflammation while investigating why it is present.

• Explain the change in concern to the owner: the eye examination shows inflammation inside the eyes, not just conjunctivitis, and bilateral anterior uveitis in a cat should prompt a search for systemic disease.
• Start treatment for anterior uveitis: because fluorescein staining is negative, topical corticosteroid treatment such as prednisolone acetate 1% is appropriate/preferred in most cats. However, this cat has possible FHV-1 recrudescence, so you opt for a topical NSAID.
• Add a cycloplegic/mydriatic, such as atropine, if needed for ciliary spasm and miosis, but only after IOP has been measured and with close monitoring. In cats, atropine ointment, if available, may be preferred to prevent severe salivation from the bitter taste of drops draining through the nasolacrimal duct.
• Provide systemic analgesia, for example buprenorphine, especially as the cat is photophobic and eating less.
• Avoid topical antibiotics alone, and avoid systemic NSAIDs before renal status, hydration and concurrent disease have been assessed.

• Minimum database: hematology, biochemistry including renal and liver parameters, electrolytes, urinalysis if a sample can be obtained, and total T4 given the age, weight loss and borderline blood pressure.
• Infectious/systemic inflammatory investigation: FeLV/FIV testing should be offered; consider toxoplasma serology depending on initial results and suspicion.
• Reassess blood pressure: 160 mmHg may reflect stress, but it is high enough to repeat under calmer conditions.
• Sample the lymph nodes: lymphadenopathy may be reactive, but enlarged peripheral nodes in a cat with weight loss and bilateral uveitis are useful to sample. Aspirates from at least one, ideally more than one, peripheral lymph node should be submitted for cytology.
• Plan close monitoring: recheck comfort, pupil size, anterior chamber flare/fibrin and IOP within 24-48 hours, sooner if pain, cloudiness, a larger pupil or reduced vision develops.

You take the samples, repeat blood pressure (158 mmHg average over 5 samples in a quieter room) and send the cat home with oral transmucosal buprenorphine, atropine 1% ophthalmic ointment or solution, and flurbiprofen sodium 0.03% ophthalmic solution. You also book a recheck for the following afternoon.

Hematology

Blood smear comment: mild normocytic, normochromic anemia with no obvious regeneration. Mild lymphopenia. No circulating atypical lymphoid population is reported.

Biochemistry

Electrolytes

Urinalysis

A free-catch urine sample is obtained while the cat is hospitalized briefly for testing.

Additional in-house/systemic tests

The new abnormalities are mild non-regenerative anemia, mild lymphopenia and hyperglobulinemia with a low albumin ratio. These make uncomplicated FHV-1 recrudescence much less convincing as a unifying diagnosis.

FeLV/FIV screening is negative, CKD and hyperthyroidism are less supported by the current renal values, urine concentration and total T4, and hypertension remains a possible contributor rather than the main explanation. The main differentials are now multicentric lymphoma with ocular involvement, FIP, toxoplasmosis and other systemic inflammatory or infectious disease. The pending lymph node cytology is now the key result.

The owner has managed the drops as prescribed. The last atropine dose was given that morning. She has noticed the eye has been squinty since.

On examination, the cat is quiet but alert. There is no obvious deterioration in his respiratory signs. A small amount of dried nasal discharge is still present. The peripheral lymph nodes remain enlarged as previously noted.

The left eye appears slightly more comfortable than at the first visit. Mild conjunctival hyperemia, miosis, aqueous flare and fine anterior chamber fibrin are still present, but the blepharospasm is reduced. IOP is 11 mmHg.

The right eye is more painful than before, with increased blepharospasm and mild diffuse corneal haze. The right pupil is larger than the left, although this is difficult to interpret because atropine has been used. Aqueous flare and fine fibrin persist and are more obvious in the right eye than the left. No discrete iris mass is seen. IOP is 36 mmHg.

Repeat fluorescein staining is negative in both eyes. The fundic view in the right eye is now limited by corneal haze and anterior chamber changes. The fundic view in the left eye remains partial but adequate; no retinal detachment or retinal hemorrhage is seen.

The enlarged right pupil could partly reflect atropine, but the IOP confirms secondary glaucoma in the right eye. This is painful and vision-threatening, so treatment should not wait for the lymph node cytology.

You admit the cat to the hospital and start aggressive glaucoma treatment, planning to recheck IOP an hour later.

Recheck

One hour and a half after starting pressure-lowering treatment, the ophthalmic reassessment shows:

The right eye has partially responded to treatment, but the pressure is not yet fully controlled. Continued monitoring is indicated, and the underlying cause of the uveitis remains unresolved. You plan to check the cat again this evening, in another couple of hours.

Before then, the lymph node cytology results come in.

The cat now has a confirmed diagnosis of high-grade multicentric lymphoma, and the bilateral anterior uveitis is very likely to represent ocular involvement by lymphoma. The diagnosis explains the uveitis, but the immediate problem has not gone away: the right eye has developed secondary glaucoma.

• Continue topical pressure-lowering treatment in the right eye and recheck IOP later the same day.
• Continue topical NSAID therapy because active uveitis is still present.
• Do not restart atropine in the right eye while IOP is raised; monitor the left eye closely because it remains uveitic.
• Discuss systemic lymphoma treatment options, including oncology referral if the owner would consider chemotherapy.
• Do not start systemic prednisolone automatically before the treatment discussion; if the owner chooses palliative care, it should be a deliberate decision.
• Be realistic about comfort: if the right eye cannot be kept comfortable despite medical management, enucleation may become a welfare-focused option.

The key point is that cytology confirmed the diagnosis, but management still has two priorities: control the painful glaucomatous eye and plan treatment for systemic lymphoma.

Patient recheck exam

The next check of the patient in the evening shows the right eye has improved to 20-22 mmHg on topical dorzolamide/timolol, although mild corneal haze and anterior chamber flare persist. The left eye remains 10-12 mmHg. The cat is more comfortable and has eaten a small amount. You decide the cat can go overnight without a recheck.

Further investigations are now aimed at staging the lymphoma, assessing fitness for treatment, and giving the owner a realistic discussion about prognosis, cost and options.

• Thoracic imaging: offer three-view thoracic radiographs to look for mediastinal widening, thoracic lymphadenopathy or pulmonary involvement. Thoracic imaging is also useful before chemotherapy or if sedation/anesthesia might be needed later.
• Abdominal ultrasound: assess abdominal lymph nodes, liver, spleen, kidneys and gastrointestinal tract. Ultrasound may identify additional sites of lymphoma and can help distinguish multicentric disease from concurrent alimentary involvement.
• Further cytology or biopsy if needed: lymph node cytology is already sufficient to support high-grade lymphoma, but additional sampling can be considered if the distribution of disease is unclear or if it would change treatment planning.
• Immunophenotyping and/or PARR: discuss whether further characterization would alter treatment choices or prognosis. Immunophenotyping may help distinguish B-cell from T-cell lymphoma; PARR can support clonality where diagnosis is uncertain.
• Bone marrow assessment only if indicated: this is not a routine first step in general practice, but may be considered if there are unexplained cytopenias, circulating atypical cells or an oncologist recommends it.
• Referral versus general practice management: oncology referral allows formal staging, protocol selection and prognosis discussion, but palliative care in general practice remains valid if referral is not possible or not desired.

The owner should understand that staging is not just more tests. It helps answer three practical questions: how widespread the lymphoma appears to be, whether the cat is well enough for treatment, and what treatment options are realistic.

In this case, the owner opts to undertake thoracic and abdominal imaging to stage the lymphoma.

Thoracic radiographs

Three-view thoracic radiographs are obtained.

Radiographic interpretation: Mild thoracic lymphadenopathy is present. There is no pleural effusion or obvious pulmonary involvement.

Abdominal ultrasound

Abdominal ultrasound is performed the same day.

Ultrasound interpretation: The findings are consistent with disseminated lymphoma, with abdominal lymphadenopathy and likely splenic and hepatic involvement. Mild intestinal wall thickening may represent lymphomatous involvement or concurrent inflammatory change.

Additional ultrasound-guided aspirates of the spleen, liver or abdominal lymph nodes could be considered, but the owner declines further sampling. The peripheral lymph node cytology has already confirmed high-grade lymphoma, and the purpose of the imaging was to guide the treatment and prognosis discussion rather than obtain another diagnosis.

 The owner listens to the options and opts for palliative treatment with prednisolone, ongoing medical management of the eyes, and euthanasia when deterioration occurs.  

Medication plan

For this 4.1 kg cat, a reasonable go-home plan would be:

If the cat is difficult to medicate, prioritize systemic prednisolone, right-eye glaucoma medication, topical anti-inflammatory treatment, then analgesia as needed. If the medication burden itself is causing distress, that should form part of the quality-of-life discussion.

Recheck plan

• 24 hours after discharge: check comfort, appetite, owner ability to medicate, and perform an ophthalmic recheck including IOP in both eyes.
• 48-72 hours later: repeat ocular examination and IOP; review appetite, weight, hydration and lymph node size.
• Weekly for the first 2-3 weeks if stable: monitor IOP, ocular comfort, uveitis, body weight, appetite, demeanor and lymph node size.
• Then every 2-4 weeks if still comfortable, with earlier review for any ocular recurrence or systemic decline.

Signs that require urgent reassessment

• the right eye becoming more closed, cloudy, red or painful, or a larger/fixed pupil developing
• sudden change in vision, bumping into objects, pawing at the face or marked light sensitivity
• reduced appetite for more than 24 hours, hiding, marked lethargy or withdrawal
• difficulty giving medication, vomiting, diarrhea, dehydration, labored breathing, open-mouth breathing or collapse

Signs that euthanasia should be considered

• persistent ocular pain or recurrent/uncontrolled glaucoma, especially if the eye is blind or likely to be blind
• inability to keep the cat comfortable without stressful or frequent medication
• anorexia or minimal intake despite palliative treatment, progressive weight loss, weakness or dehydration
• respiratory difficulty, collapse, severe lethargy, hiding, loss of normal interaction or repeated bad days outnumbering good days

If the right eye becomes blind and painful but the cat is otherwise doing well, enucleation can be discussed as a comfort procedure. Given the disseminated lymphoma, this should be weighed against expected survival time, anesthetic burden, cost and the owner's goals.

The plan should be recorded clearly: this is palliative care, with active treatment for comfort, not curative treatment. The agreed endpoint is euthanasia when ocular pain, systemic decline or medication burden can no longer be managed in a way that preserves the cat’s quality of life.

• A bilateral red eye with discharge is not always conjunctivitis; miosis, photophobia, aqueous flare and low IOP should redirect the case toward anterior uveitis.
• Bilateral anterior uveitis in a cat should trigger a systemic work-up, particularly when accompanied by weight loss, anemia, hyperglobulinemia or lymphadenopathy.
• Atropine can complicate interpretation of pupil size. Repeat IOP is essential when a uveitic eye becomes more painful or cloudy.
• Secondary glaucoma is an ocular emergency even when the underlying systemic diagnosis is still pending.
• Lymphoma can present through the eyes, but treatment planning still needs to address both systemic disease and ocular comfort.