A 7-year-old neutered male Birman cat is brought in for a...

Ah, acute onset blindness with bilateral retinal detachment in a cat – this is a serious and urgent presentation, and it demands a thorough systemic investigation. Unlike dogs, where primary retinal detachments (rhegmatogenous, often due to vitreous degeneration) are more common, in cats, bilateral exudative retinal detachments are almost invariably secondary to systemic disease. The retina is being lifted off the underlying choroid by fluid accumulation, which signifies a problem with the choroidal vasculature or systemic fluid dynamics.

When I see a case like this, my mind immediately goes to the most common culprits, but I always ensure a comprehensive workup to avoid missing a less obvious, but equally critical, diagnosis.

Here are the systemic conditions that must be investigated as potential underlying causes for a 7-year-old Birman cat presenting with acute blindness and bilateral retinal detachment:

Systemic Hypertension: This is, by far, the most common cause of bilateral exudative retinal detachments in older cats. Chronic hypertension leads to choroidal vasculopathy, causing leakage of fluid and protein into the subretinal space, ultimately resulting in detachment. It can also cause intraocular hemorrhage and perivascular cuffing.

Action: This is the first* thing I would measure. A blood pressure reading is paramount.

Chronic Kidney Disease (CKD): A very frequent underlying cause of systemic hypertension in older cats. The kidneys play a critical role in blood pressure regulation, and their dysfunction often leads to hypertension, which then manifests ocularly as retinal detachment.

* Action: Full chemistry panel (BUN, creatinine, phosphorus, SDMA), complete blood count (CBC), and a complete urinalysis (specific gravity, protein:creatinine ratio).

Hyperthyroidism: Also common in older cats, hyperthyroidism can independently cause systemic hypertension or exacerbate pre-existing hypertension, thus contributing to ocular pathology.

* Action: Serum total T4 concentration.

Cardiac Disease: While less common for directly causing bilateral exudative detachments, underlying cardiac disease can contribute to hypertension, or in rare cases, lead to thromboembolic events that could impact ocular circulation.

* Action: Thoracic radiographs and possibly an echocardiogram if blood pressure is normal but other systemic signs are present.

Hyperviscosity Syndrome/Polycythemia: Any condition that increases blood viscosity (e.g., polycythemia vera, certain myeloproliferative disorders, multiple myeloma with hyperglobulinemia) can lead to impaired ocular blood flow, vascular fragility, and subsequent exudative detachment or hemorrhage.

* Action: CBC (especially hematocrit/PCV), serum protein electrophoresis if hyperglobulinemia is suspected.

Infectious Diseases: A range of systemic infections can cause chorioretinitis, which can progress to exudative retinal detachment.

* Fungal Infections: Cryptococcosis is a classic cause of chorioretinitis and granulomatous disease in cats, often leading to retinal detachment. Other systemic mycoses (Histoplasmosis, Blastomycosis, Coccidioidomycosis) are less common in cats but possible depending on geographic location.
* Toxoplasmosis: Can cause chorioretinitis and uveitis.
* Feline Infectious Peritonitis (FIP): The "wet" form, in particular, can cause significant vasculitis and exudation, leading to uveitis and retinal detachments.
* Feline Immunodeficiency Virus (FIV) / Feline Leukemia Virus (FeLV): While not direct causes of detachment, these can predispose to other ocular infections or intraocular inflammation/neoplasia.
* Action: Infectious disease titers (e.g., Cryptococcus antigen test, Toxoplasma IgG/IgM, FeLV/FIV testing), and potentially aqueous or vitreous taps for cytology and PCR in refractory cases.

Neoplasia: Lymphoma is a significant consideration in cats, and can infiltrate the choroid, leading to inflammation and exudative detachment. Other systemic malignancies could also metastasize to the choroid or cause paraneoplastic syndromes.

* Action: Thorough physical examination for lymphadenopathy, abdominal palpation, thoracic radiographs, abdominal ultrasound.

Emergency Management & Diagnostics:

Given the acute blindness and retinal detachment, this cat needs immediate attention. My initial steps would be:

STAT Blood Pressure Measurement: Using a Doppler or oscillometric device.

CBC, Chemistry, Urinalysis: To assess kidney function, hydration, and look for signs of systemic inflammation or other metabolic derangements.

Total T4: To rule out hyperthyroidism.

Ocular Ultrasound: To confirm the extent of the detachment, assess for vitreal hemorrhage, intraocular masses, or choroidal thickening, and evaluate the integrity of the globe.

While we await the full diagnostic results, if severe hypertension is detected, I would initiate appropriate antihypertensive therapy immediately to try and preserve vision. The prognosis for vision is guarded but possible with prompt and effective treatment of the underlying systemic cause.

This is not "just a red eye." This is a systemic disease manifesting in the eye, and it requires a full body investigation.