It is a relatively rare affliction for dogs and appears to be more common in cats.  Although the presence of hypopyon in a dog is not an immediate life threatening condition, it is important to get your dog to a veterinarian because there is a very real threat of him losing his eyesight, and it is undoubtedly a sign of a more serious underlying condition.

Hypopyon in dogs is defined as a collection of white blood cells (or pus) in the front (anterior) of the eye. An abscess in the eye, it is considered to be a symptom of another underlying, serious condition. It comes on fast and is extremely alarming to the pet owner. Dogs of all breeds, age, and sex can be affected. 

Your dog's eye will quite dramatically change color resulting in an cloudy often yellowish appearance. Other clinical symptoms include:

Hypopyon is often confused with a lipid flare. They are entirely different conditions, but it is worth mentioning here because of the confusion. Hypopyon is a much more serious condition than a lipid flare. Although a lipid flare can resemble hypopyon, lipid flare is a result of a buildup of fatty substances in the cells within the eye. A lipid flare’s most telling characteristic is a milky white appearance. Some veterinarians will proceed with treatment as a diagnostic tool. Often lipid flare will respond to treatment, whereby hypopyon will not.

Hypopyon develops in a  dog that has experienced anterior  uveitis (inflammation.)The presence  of hypopyon is always caused by an underlying condition of the eye. It is sometimes caused by a bacterial or fungal infection. The infection can also be viral or parasitic in nature. Lyme disease is an excellent example of an infectious condition that can lead to hypopyon. Some cancerous tumors of the eye can also contribute to a hypopyon. Hypopyon can sometimes develop shortly after the dog is vaccinated.

Diagnosis of hypopyon often requires a veterinary optometrist. Standard tests such as a blood count and urinalysis are common. It will be important to determine what caused the condition.Your veterinarian will likely test for glaucoma, corneal ulcers, and fungal or parasitic infections.  The importance of determining an underlying disease process, or ruling out illnesses that present in similar ways will be evident when the diagnosis is reached. 

A hypopyon condition can be very painful. Even the most mild mannered dogs may have difficulty in the veterinarian's office. Sedation may be needed as the veterinary doctor evaluates the extent of the problem. This will enable the veterinary doctor or specialist to fully view the eye and confirm the extent of the problem.

It is not uncommon to begin aggressive treatment even before diagnostic results are returned because time is of the essence in regards to saving the dog’s eyesight. Topical and oral antibiotics are often used as well as anti-inflammatory drugs. If there is inflammation, corticosteroids may be administered, depending on the current health condition of your dog. Atropine will protect your pet’s eye and also provide some pain relief. Treatment is also concentrated on the underlying disease that caused the symptom of hypopyon.

Prognosis for dogs with hypopyon is guarded. It is a very real possibility that your dog may lose his sight. With time, many dogs are able to live happy lives without vision. Sometimes other family dogs will act as a seeing eye dog for the blind or visually impaired. It is important to determine the underlying condition that caused the hypopyon, and treat it. Always finish the course of any medication or ointments that your veterinarian prescribes. She may suggest periodic follow up appointments to ensure the condition is under control.