Tear ducts in dogs are small holes, called puncta, located on the upper and lower eyelids. They allow tears to drain into a collection sac just beneath the skin below the eyes. A small tube then carries the fluid from this sac into the nose. Proper drainage of tears is essential to keep the eyes healthy and nose moist. When the tear ducts are blocked, the tears run down over the face. Blocked ducts are prone to infection and swelling, which can cause serious damage to the eyes.

Blocked tear ducts are a problem for all dogs but are especially common in small breeds As many as one in five small dogs is born with partial or complete blockages of their lower tear ducts, and dealing with this problem over the dog's life can be expensive. Tears help keep the eyes clean, moist and free of debris. When a malfunction occurs in the process, significant vision problems can develop. In severe cases, surgery might be needed to prevent blindness.

Initially, a blocked tear duct might only cause excessive tearing or a cessation of tearing. A brown or pinkish stain might appear beneath the dog's eye where the tears drain. After a few days, the duct begins to swell and might turn red. These symptoms are usually the result of a developing infection. As the swelling increases, the duct pushes against the surrounding eye tissue. If left untreated, the dog might develop a prolapse of the third eyelid, or cherry eye, which appears as a large, red swelling.

Numerous things cause blocked tear ducts in dogs. In some, the cause might be hereditary, and certain breeds are more susceptible to developing the condition. Eyelids that turn inward can also block the drainage of tears. Irritation caused by allergies, hair or other particles in the tear duct is another cause. Complications from previous eye infections, inflammation of the tear ducts and kinking of the drainage ducts in the nose also can all obstruct the flow of tears.

Treatment of blocked tear ducts in dogs depends on the underlying cause of the condition. When infection is responsible, treatment with antibiotics and eye rinses is usually sufficient to clear the blockage and prevent complications. If blocked ducts are caused by allergic irritation and inflammation, exposure to the allergen must be avoided, and medication might be prescribed to reduce the body's reaction to the offending substance. Proper hygiene and grooming is essential to treat existing blockages and prevent the development of new ones. Irrigation of the tear ducts can be performed by your veterinarian. In severe cases, surgery to open or widen the ducts might be necessary.

Untreated eye infections and blocked tear ducts can result in permanent eye damage or blindness. Some dogs, especially smaller breeds, are more vulnerable to serious eye complications caused by blocked ducts. Symptoms should never be ignored. While you can attempt to encourage opening and drainage by applying warm compresses, any dog with persistent symptoms should be evaluated and treated by a veterinarian to protect the eye from damage.