Eyelash Abnormalities - Distichiasis and Ectopic Cilia
Both of these issues involve the abnormal growth of eyelashes. With distichiasis, a condition Pugs are moderately prone to, one or more eyelash grows in an odd direction out from the eyelid. With ectopic cilia, a condition seen less commonly with Pugs, one or more eyelash grows through the inside of the eyelid toward the eye.
With either condition, when an eyelash pokes into the eyeball, it is extremely painful and can lead to corneal ulcers.
Signs of this include eye pain (a Pug may paw at the eye), abnormal twitching of the eyelid, bloodshot eyes, excessive tearing, and/or change in iris pigmentation.
Although an offending eyelash can be plucked out, offering immediate relief, it is often temporary since it usually regrows within 4 to 5 weeks. For this reason, a minor procedure is often performed to remove both the eyelash and the follicle to prevent any reoccurrence.
Entropion, also referred to as inverted or folded-in lid, is an inherited condition in which either the upper or lower eyelid rolls inward. This is moderately common with Pugs, usually involves the lower eyelids, and typically develops within the first year. This is mainly a genetic condition linked to tension in the ligaments of the inner eye but can also be triggered by rapid weight loss or can develop alongside chronic eye infections.
While the inverted lid itself will irritate the eye, there are other issues that can develop. Eyelashes that that point inward can scratch the surface of the eye, leading to corneal ulcers. And, any scar tissue that may form after a scratch that can lead to vision problems or even vision loss in some cases.
Signs include excessive tearing, inflammation around the eye, and/or signs of irritation or pain.
In very minor cases, and if the cornea is not ulcerated, the eyelid may be temporarily stitched back into place and artificial-tear medication given. However, in most cases, this needs to be resolved with corrective surgery to permanently reposition the eyelid back into position.
Corneal Abrasions and Ulcerations
The cornea is the clear, shiny membrane that makes up the surface of the eyeball and because Pugs have very prominent eyes, corneal abrasions and ulcers are not uncommon.
The cornea has 4 layers which are, in order of top to bottom layer, the epithelium, basement membrane, stroma, and Descemet’s membrane.
- A corneal abrasion is a scrape that only affects the epithelium (1st layer).
- A corneal ulcer is a scrape through the whole epithelium (1st layer) and into the basement membrane (2nd layer) or stroma (3rd layer).
- Descemetocele is a scrape through the epithelium, basement membrane, and stroma (1st 2nd, and 3rd layers) and to the level of Descemet’s membrane (4th and deepest layer). If the Descemet’s membrane ruptures, liquid inside of the eyeball leaks out and the eye actually collapses.
The most common cause of abrasions and ulcerations is trauma to the eye which can be anything from debris entering a Pug's eye to rubbing the head along the ground resulting in a scratch. This is also linked to entropion, chronic eye infections, keratoconjunctivitis sicca (dry eye), canine diabetes, and hypothyroidism.
Signs include moderate to severe pain (a Pug may paw at the eye or rub the eye area against surfaces), sensitivity to light, keeping the eye closed, discharge (in some cases).
To diagnose this, the veterinarian will numb the eye, drop a fluorescein stain onto the eye, and then use a particular black light called a Wood’s light which allows abrasions and ulcerations to be visible.
Exact treatment will depend on whether there is a corneal abrasion, ulcer, or descemetocele.
Corneal abrasions generally are treated with topical antibiotics and often the use of a protection cone collar to prevent a dog from pawing at the eye and typically heal in 1 week or less.
For corneal ulcers or descemetocele, treatment varies. For moderate cases, surgery may be performed to temporarily stitch the eyelid closed to allow it to heal. If both eyes are affected, each eye may be alternatingly treated. For more serious cases, other surgery including grafts or transplants may be required.
If an ulcer does not heal as expected, there can be a buildup of dead cells on the rim of the ulcer which prevent normal cells from repairing the tear. If this happens, the dead cells are removed and surgical closing of the eyelids may follow.
Note: Sometimes, a dog will be misdiagnosed as having a minor abrasion, when it’s actually an ulcer. If there is no improvement after 2-3 days of treatment, bring your Pug back to the vet to be reexamined.
Pigmentary keratitis refers the migration of brown (melanin) pigment from the iris into the sclera (white area of the eye). This can range from minor (which has no affect on vision) to severe (melanin covers the pupil, leading to blindness). Early detection plays a huge role in successfully managing and treating this.
Up to 50% of Pugs have some level of pigmentary keratitis. This may develop with no underlying causes, however it is frequently linked to other issues such as entropion or keratoconjunctivitis sicca (dry eye).
The sign of this is brown pigment seen within the sclera (white part of the eye). It can vary from faint (tiny brown specks) to severe (black patches).
Because many cases are due to an underlying eye issue, treatment almost always involves resolving that underlying disorder. Therefore, if entropion is present, it will be treated with surgery to reposition the eyelid. If keratoconjunctivitis sicca is the culprit, it will be treated either with topical medications or, in rare cases, surgery to reposition the salivary duct. When the underlying cause is successfully treated, this will usually stop pigmentary keratitis from developing any further.
In regard to the pigmentation that has already migrated to the cornea, there is very rarely an attempt to surgically remove it due to the risks involved, and there are no medications that have been proven to eliminate it. In time (months or even years), the pigmentation may lighten on its own.
When caught early, prognosis is good. However, prognosis worsens the longer it takes to have this diagnosed. If the pigmentary keratitis already reached a severe level and is covering the pupil, this can profoundly affect a Pug's vision, even leading to blindness.