Hypopyon and Lipid Flare in Dogs
Hypopyon is characterized by an inflammatory disruption of the blood-aqueous barrier in a dog’s eye, enabling the entry of blood cells into the anterior chamber. This leads to an accumulation of white blood cells within the chamber, forming a fluid line due to gravity’s effect.
In contrast, lipid flare presents a cloudy appearance in the anterior chamber similar to hypopyon. However, the cloudiness results from a high concentration of lipids in the aqueous humor, which requires both a breakdown of the blood-aqueous barrier and concurrent hyperlipidemia. This condition can occur without regard to age, gender, or breed predisposition.
Symptoms
Hypopyon
Hypopyon refers to a white to yellow opacity observed within the front portion of the eye. This opacity can either collect as cells in the lower part or completely fill the front chamber of the eye. Other accompanying signs in the eye may include:
- Twitching of the eye (blepharospasm)
- Excessive tear production (epiphora)
- Generalized swelling of the cornea
- Presence of aqueous flare
- Constriction of the pupil of the eye (miosis)
- Swelling of the iris
- Loss of vision or blindness
Lipid flare
The anterior chamber presents with a diffuse milky appearance, typically obstructing the view of internal eye structures. Associated ophthalmic signs may involve:
- Loss of vision
- Mild twitching of the eye (blepharospasm)
- Mild to moderate swelling across the cornea
Causes
Hypopyon:
Underlying conditions leading to uveitis, inflammation of the middle layer of the eye, can trigger hypopyon. Typically, hypopyon is most commonly associated with severe forms of uveitis. However, it can also arise from the accumulation of tumor cells, particularly in cases of ocular lymphoma (eye tumors).
Lipid Flare:
Lipid flare often stems from hyperlipidemia, characterized by elevated or abnormal levels of lipids in the bloodstream, and the concurrent breakdown of the blood-aqueous barrier due to uveitis. Hyperlipidemia can directly destabilize the blood-aqueous barrier. Additionally, heightened levels of lipids in the blood after a meal (postprandial lipemia) may occasionally manifest as lipemic aqueous when uveitis is present.
Diagnosis
Your veterinarian will conduct a comprehensive physical and ocular examination of your dog, considering the history of symptoms and potential incidents leading to the present condition.
Hypopyon can be identified by the presence of fibrin, the protein end product of coagulated blood, in the anterior chamber, typically forming an irregular clot rather than a horizontally located line at the bottom.
To differentiate lipid flare from severe aqueous flare, which lacks the milky/white appearance of lipid flare, careful observation is necessary. Dogs experiencing severe aqueous flare often display more significant ocular pain compared to those with lipid flare.
Diffuse corneal edema, characterized by severe corneal swelling, may be mistaken for anterior chamber opacity. However, features such as corneal stromal thickening, keratoconus (a degenerative non-inflammatory eye disorder), and corneal bullae (fluid-filled blisters) are more commonly associated with diffuse corneal edema than with hypopyon or lipid flare.
Treatment
Hypopyon demands aggressive treatment targeting the uveitis and its root cause. While outpatient care is typically sufficient, it’s important to recognize the considerable risk of vision loss for your dog.
For lipid flare, treatment addresses the mild uveitis and any underlying metabolic issues. If hyperlipidemia is diagnosed, dietary adjustments are necessary to reduce fat and calorie intake, thereby lowering fat levels in the bloodstream. Outpatient care, often involving anti-inflammatory medications for home use, is usually effective.
Living and Management
Your veterinarian will arrange a follow-up appointment for your dog within two to three days after initiating treatment. Monitoring of intraocular pressure within the eyes is essential to detect potential secondary glaucoma. Subsequent rechecks will depend on the severity of the disease and your dog’s response to treatment.
The prognosis largely hinges on the underlying condition causing the eye ailment. In cases of hypopyon, the prognosis is cautious, influenced by the underlying disease and treatment response. Conversely, lipid flare typically carries a favorable prognosis. It often responds promptly (within 24–72 hours) to moderate anti-inflammatory therapy. However, be aware that recurrence and the need for additional treatment are possible with lipid flare.