If your pet is blinking excessively, has swollen tissue around an eyelid or the surface of the eye, or has a prominent third eyelid, then she may be suffering from dry eye syndrome. This condition is also called Keratoconjunctivitis sicca, or KCS. Other symptoms can include discharge from the eye or changes in the cornea’s blood cells, including pigmentation and ulceration.

If you notice these symptoms in your pet, then you should take her to the veterinarian for a thorough examination as soon as possible. If KCS ends up being the issue, then tacrolimus may be the medicine your vet prescribes to treat the condition.

What Is Tacrolimus?

Tacrolimus is part of a relatively new class of drugs called Calcineurin inhibitors. It is designed to inhibit the enzymatic action of Calcineurin, a calcium and calmodulin dependent serine/threonine protein phosphatase that activates the T-cells of the immune system. Tacrolimus has anti-inflammatory, immunosuppressive, and immunomodulatory properties that make it suitable for a variety of treatments in the veterinary field.

Why Tacrolimus Is Prescribed in Veterinary Medicine

Tacrolimus is most commonly prescribed by veterinarians to treat dogs and cats that have been diagnosed with Keratoconjunctivitis sicca. The drug is most often prescribed as an alternative treatment solution for pets that have not benefitted from Cyclosporine. However, more veterinarians are starting to prescribe tacrolimus as the initial course of treatment for KCS due to its effectiveness. Dogs and cats that are diagnosed with dry eye will need to take tacrolimus for the rest of their lives because there is currently no known cure for KCS.

Other Uses for Tacrolimus in Veterinary Medicine

Because of tacrolimus’s broad range of medicinal properties, it has also shown promise in the treatment of other health problems among pets, and particularly in cats. In addition to treating pets with KCS, the topical form of tacrolimus may also be used to treat cats that have been diagnosed with:

• Atopic dermatitis

• Pemphigus

• Lupus erythematosus complex

• Miliary dermatitis

• Eosinophilic granuloma complex

Dosage and Administration of Tacrolimus

Tacrolimus should be administered to the pet exactly as prescribed by your veterinarian. Because this is a topical medication, it is important to be patient when applying it to your pet because animals will struggle when having medication applied to their eyes. Wear disposable gloves when administering tacrolimus to your pet, and try not to let the medication touch your skin.

Do not touch the tube or container tip to your pet’s eyes, and do not touch the tube or container tip with your finger after applying the medication to your pet’s eye. The veterinarian will most likely show you how to apply the topical solution to your finger and then to your pet’s eye, so be sure to follow those steps to prevent contaminating the tube or container.

If you need to apply another eye medication, wait at least five minutes before doing so. If you miss a dose, restart the treatment at the next scheduled dose time. Do not apply a double dose or try to catch up by giving two doses close together.

After applying tacrolimus to your pet’s eye, remove the gloves and wash your hands thoroughly.

Special Precautions for Using Tacrolimus

Tacrolimus should only be administered to the pet that it has been prescribed for. Keep it out of reach of children and pets.  Because tacrolimus can also be found in the treated animal’s saliva, urine, and feces, you should always wear gloves when disposing of cat litter or dog droppings, or when cleaning up urine spills. You should also be careful not to let treated animals lick human skin. If skin exposure does occur, the area should be washed thoroughly with soap and water. Pregnant women should NOT handle tacrolimus.

Tacrolimus should be used with caution in pets that are pregnant or nursing.

Possible Side Effects of Tacrolimus

Tacrolimus is usually tolerated well when it is applied as directed for the treatment of dry eye syndrome. Therefore, side effects are usually not an issue, but may still occur. Potential side effects may include loss of hair around the eye, mild burning at the site of treatment, and eye spasms.

Side effects are more likely to develop when the drug is used to treat dermatologic conditions, because the pet is more likely to ingest it by licking the treated area. In this case, the most common side effects are GI-related, such as nausea, vomiting, constipation, or diarrhea.

If your pet experiences discomfort or irritation in the eyes after being treated with tacrolimus or has difficulty breathing or swelling in the throat, notify the treating veterinarian immediately.

Known Drug Interactions With Tacrolimus

There are no known drug interactions with tacrolimus at this time. If your pet is taking other medications or supplements, you should let the veterinarian know about them. This includes notifying your veterinarian of the drug dosages and administration schedules, to help avoid any potential risks.