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Corneal Ulcer in Dogs

Corneal Ulcer in Dogs

Corneal ulcer or ulcerative keratitis is a very common canine eye diseases and it can sometimes affect cats too. In general, a corneal ulcer can be defined as a condition in which the outer layer of the cornea is damaged and lost. This condition develops due to various reasons, like trauma, eye infections or by exposure to chemicals. Corneal ulcer in dogs is a serious medical condition that may lead to loss of vision. Hence, early diagnosis and immediate treatment is absolutely necessary. As a pet owner, you must have a basic idea about this canine eye condition, its causes, symptoms and treatment.

Dogs Cornea
In order to understand the disease, you may need to know more about the cornea of dogs. A dogs cornea is made up of four layers - outer epithelium, followed by the corneal stroma, then Descemets membrane and the last endothelium. Cornea, as a whole, is a transparent membrane that is around one millimeter thick in the case of dogs and cats. This part of the eye does not have any blood vessels or pigmentation and so, it is transparent in nature. The arrangement of collagen fibers also contribute to the transparency of the cornea. However, nerves are present in the cornea and pressure and pain receptors are also there. The cornea is responsible for refracting light, thereby enabling the pet to focus on an object and to protect the inner layers of the eye.

Corneal Ulcer in Canines
The condition denotes the cell loss in the corneal epithelium (that may be accompanied by a loss of the underlying corneal collagen) due to various reasons that will be discussed later. Injury to the corneal epithelium is common in dogs and cats. In most cases, the lost cells are naturally replaced by new ones and the ulcer is healed fully. But in some cases, either the new cells are not formed or the newly formed cells are weak to cause further injury or infection. Such corneal ulcers may allow microorganisms to enter the eye and the eye gets infected. Otherwise the ulcer may spread to the deeper layers of the eye and may lead to eye ruptures.

Corneal ulcer in dogs can be of two types - superficial and deep. While the superficial ulcers involve a loss of the outer layer of the cornea (partial or full), deep ulcers cause a loss of more than one half the thickness of the cornea, as it extends through the stroma. Superficial ulcers take only a few days to heal, whereas the deep ones need much more time for healing. The latter category may leave a corneal scar or may re-ulcerate or may refuse to heal. The healing process involves either by a shifting of the surrounding epithelial cells to fill the space by rapid cell division or by an introduction of blood vessels to that area from the conjunctiva. In the latter case, white blood cells and fibroblasts produce scar tissue to cover the area. The first type of healing can be seen in superficial ulcers and the second type occurs in deep ulcers.

Causes and Symptoms
Dogs eyes are prone to corneal ulcers, as they indulge in many activities that may cause scratches and injuries to the cornea. A scratched cornea in dogs may occur by their own paw rubbing, by a blade of grass, by fighting with other animals and by ingrown or misplaced eyelashes. Ulcers may also develop from eye infections caused by viruses or bacteria, exposure to chemicals (like that in harsh shampoos) and heat or smoke. Dry eye or keratoconjunctivitis sicca (reduction in tear production) is another reason for corneal ulcers in dogs. Inadequate blink responses may also give rise to this condition. However, it is mostly seen in dog breeds with protuberant eyes and also in older dogs. As the condition is painful, the symptoms of corneal ulcer in dogs include increased pawing or rubbing at the eye, squinting, redness, tearing, cloudy cornea, red or green mucus discharge form the eye, redness of the eyelids and the area surrounding the cornea, lethargy and changes in normal dog behavior.

Treatment for Canine Corneal Ulcer
If you notice any of the above said symptoms, take your pet dog to a veterinarian immediately. The doctor will conduct a diagnosis through direct observation, after using fluorescein stain. They may also resort to tests like, Schirmers test for detecting dry eyes or tests to analyze facial nerve function, to detect facial nerve paralysis. If the cause is eye infection by bacteria or virus, samples are collected for conducting cytology, culture and antibiotic sensitivity, in order to find out the particular infectious agent.

The most common treatment for corneal ulcer in dogs includes pain medication and topical application of antibiotics to prevent the infection. This treatment may be sufficient to heal superficial corneal ulcers, but deep ones may require suturing, conjunctival grafts or conjunctival flaps. In some cases, soft contact lenses are used, whereas some others may undergo corneal transplant. The affected dogs may be fitted with an e-collar around their necks, to prevent them form rubbing the eyes with paws. For severe corneal infections, oral antibiotics are also administered and oral anti-inflammatory drugs are given if there is inflammation inside the eye. However, topical application of corticosteroids and anesthetics is avoided, as these drugs can make the situation worse.

However, the most important point is that you have to treat the condition of your pet dog at the earliest, to avoid complications, like loss of sight. With good dog care this common dog illness can be easily overcome.

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