Effective Treatments for Canine and Feline Dry Eye Synd

Common symptoms in sick animals include a sticky or mucopurulent discharge adhering to the surface of the eye, along with conjunctival congestion, thickening, or swelling. The eyelids may also spasm. If left untreated for an extended period, these issues can lead to corneal ulcers or even perforations. In chronic cases, you might observe neovascularization or melanosis of the cornea, which can impair vision and, in severe cases, result in blindness.

Animals with dry eye syndrome often exhibit a dry, lackluster appearance of the cornea due to the absence of a tear film. In cases of neurogenic dry eye, the affected animal's nostril on the same side tends to be particularly dry and uncomfortable.

The etiology of dry eye syndrome in animals includes factors such as medicationinduced, such as the toxic effects of sulfonamide drugs on lacrimal gland tissue; surgeryinduced, like the development of dry eye in animals that have had their third eyelid glands removed within 45 years postsurgery; and injury to the facial nerve, which can also lead to dry eye. The lacrimal gland cells are typically immuneprivileged, isolated by the bloodtear barrier. When this barrier is compromised, the immune system may attack the lacrimal gland tissue, causing dry eye—a common cause in dogs. Other factors include orbital and periorbital injuries, infections like canine distemper, senile gland atrophy, and neurogenic issues, where a lack of parasympathetic stimulation to the lacrimal glands and other neurological abnormalities (such as trigeminal nerve dysfunction) can lead to dry eye. Neurogenic dry eye usually affects one side and may present with dryness in the affected nostril.

Diagnosis

Diagnosing dry eye syndrome involves considering the animal's medical history, clinical symptoms, and tear tests. If tear production is below 15mm per minute, the animal should be suspected of having dry eye. Additional tests, such as the Bangladesh Red Test and BUTT test, may be necessary. A comprehensive veterinary examination, including bloodwork and other tests, should be conducted to rule out other systemic or immune diseases, such as diabetes, hypothyroidism, rheumatoid arthritis, myositis, or lupus, which can cause dry eye.

Treatment Essentials

Treatment for dry eye syndrome involves both medical and surgical approaches. Initially, medical treatment is typically employed, with the vast majority of affected animals responding positively. The cooperation between the owner and the animal is crucial for successful treatment. Medications include tear stimulants, such as cyclosporine A (CsA) and tacrolimus, and tear film substitutes to maintain ocular health when tear production is insufficient.

There are various artificial tears and lubricating agents available on the market. Animals can try different types of artificial tears initially and then choose the one that works best for them. Additionally, secondary infections associated with dry eye must be controlled. When the eye surface is dry and inflamed, you may notice purulent discharge. The veterinarian will select an antibiotic based on experience and sensitivity testing. For neurogenic dry eye, oral pilocarpine can stimulate tear production. To ensure the medication reaches the eye effectively, it's important to clean away any discharge before applying the drops.

When tear production continues to decline, the owner is unable to manage the symptoms with medication, or if the animal's clinical symptoms cannot be controlled with medication for more than six months, a sialoadenectomy surgery may be considered. Following surgery, most animals will still require ongoing medication to maintain eye health.