Distichiasis is quite common in dogs. Distichiasis is a condition in which extra hairs grow out of the eyelash area. It happens when there are two or more hairs growing out of a Meibomian gland opening. (Meibomian glands are located along the margin of the eyelid.) These hairs are not supposed to be there. In some cases, these extra hairs can be long and stiff and irritate the eye, resulting in a corneal ulcer. The severity of the problem depends on how stiff the hairs are, how long they are, where they’re located, and how many extra hairs there are.

Distichiasis is different from entropion. Distichiasis involves extra eyelashes; entropion is an inward roll of the eyelid that causes eye irritation from normal eyelashes or hair.

Untreated distichiasis can cause corneal ulcers, chronic eye and eyelid pain, and excessive tearing. It is quite uncomfortable and/or painful for the animal, depending on the amount irritation. If the excessive hair causes any clinical signs at all, the hair should be permanently removed.

Signs include increased blinking, lots of extra tears that often look like a tear streak, and squinting. Dogs don’t typically paw at the eye. The more severe cases are the most easily diagnosed, as the milder cases often involve small softer hairs that can easily be missed.

It’s seen most often in puppies or young adults and is typically diagnosed before a dog is three years old. Any dog can have it, but it’s considered to be one of the most commonly inherited diseases in dogs, and considered by some to be the most common congenital eye problem.

Breeds that seem to be predisposed to distichiasis include:

• Cocker spaniel
• Cocker Spaniel, American
• English bulldog
• Flat-coated Retriever
• Golden retriever
• Lhasa apso
• Miniature Longhaired Dachshund
• Miniature poodle
• Pekingese
• Poodle
• Pug
• Shetland sheepdog
• Shih tzu
• Toy poodle
• Yorkshire terrier

Treatment

There are several treatment options and your veterinarian’s choice will generally depend on how many extra hairs are involved and what equipment the veterinary facility has. General anesthesia is usually needed. Occasionally a very cooperative dog might allow treatment with only a local anesthetic, but that would be extremely rare.

1. Cryosurgery freezes the lid margin at the places where there are extra hairs.
   
2. Surgery will remove the hairs permanently.
   
3. Electrolysis will remove the hairs permanently.

These procedures destroy the hair follicles, preventing hair regrowth. However, no procedure can be guaranteed, so retreatment may be necessary in some cases. Several follow-up visits will be needed, to make sure that the hairs are not going to regrow.

Plucked hairs will just grow back, so plucking is not a permanent solution. Lid splitting and thermocautery can destroy the normal lid margins, leading to severe permanent scarring and entropion, so they are not good treatment options.

The eyelids will have some post-operative inflammation, which your veterinarian will also treat.

Prognosis

Once the hairs have been removed permanently, the prognosis is good. However, dogs with distichiasis should not be used for breeding, because of the hereditary aspects.