Dermoid
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Breeding advice appliesUse the condition’s screening guidance and veterinary or genetics advice before breeding an affected or at-risk animal.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
An ocular dermoid is a congenital developmental abnormality in which normal skin-type tissue grows on the surface of the eye. The tissue can contain skin, hair follicles, sebaceous glands and fat, and may be attached to the conjunctiva, cornea or both. It is present from birth even if it is not noticed immediately. A breed predisposition has been described in Dalmatians and several other breeds, suggesting an inherited component in some lines, although the exact genetic mechanism has not been established.
The appearance varies with the size and location of the dermoid. It may look like a small patch of pigmented skin on the white of the eye or a raised area extending onto the clear cornea. Hair growing from the abnormal tissue can rub repeatedly across the corneal surface. This mechanical irritation may cause tearing, squinting, redness, recurrent inflammation or corneal ulceration. A dermoid positioned away from the cornea may cause little discomfort, while one covering part of the visual axis can interfere with sight.
The veterinarian assesses how deeply it involves the cornea and whether the surrounding surface is already damaged. Referral to a veterinary ophthalmologist is useful when the lesion extends deeply into the cornea or occupies a large area.
An ocular dermoid is not a tumour and does not spread through the body. The concern is local irritation and disruption of a normally smooth, transparent eye surface. Because the abnormal tissue will not disappear as the puppy grows, treatment decisions are based on its position, size and effect on comfort or vision. Complete removal generally provides an excellent outcome.
Breeders of predisposed lines can also look for an unusual pigmented patch, hairs emerging from the eye surface, persistent tearing or one eye that remains partly closed.
Screening & Early Detection
Because an ocular dermoid is present from birth, early detection is usually possible during routine puppy examinations. The eyes should be inspected carefully when the puppy is first assessed by a veterinarian, commonly around six to eight weeks of age.
A veterinarian examines the conjunctiva and cornea with magnification and may use fluorescein stain to check for an ulcer caused by rubbing hairs. The position and depth of the dermoid are recorded because a superficial lesion at the edge of the eye is different from a lesion extending deeply into the central cornea. A veterinary ophthalmologist may use slit-lamp examination to define the lesion more accurately before surgery.
There is no routine blood test or established carrier-screening test for this condition. A normal eye examination after birth is therefore the practical screening method. Any puppy with persistent unilateral tearing, redness or squinting should be examined even if the dermoid is not obvious to the owner, as a small lesion may be hidden near an eyelid margin.
Affected dogs should be recorded in breeding histories because recurrence within a family may indicate inherited susceptibility, even when no specific DNA test is available.
Diagnosis is usually straightforward during a careful eye examination because the tissue has a distinctive skin-like appearance.
Treatment & Management
Treatment is surgical when the dermoid causes irritation, threatens the cornea or interferes with vision. The abnormal skin tissue is carefully removed, usually while the dog is still young. When the dermoid is confined to the conjunctiva, excision can be relatively straightforward. Lesions involving the cornea may require a superficial keratectomy, in which the abnormal tissue and a thin layer of affected cornea are removed under magnification.
Complete excision is important because residual dermoid cells can allow the lesion or hair growth to recur. At the same time, the surgeon must preserve as much healthy corneal tissue as possible. Large or deep lesions are therefore best managed by a veterinary ophthalmologist with appropriate microsurgical equipment.
After surgery, topical antibiotic and anti-inflammatory medication may be prescribed, together with pain relief and an Elizabethan collar to prevent rubbing. The corneal surface is monitored while it heals. Some scarring can remain, particularly when a large portion of the cornea was involved, but vision is usually good if the central cornea was not deeply affected.
Very small dermoids that do not touch the cornea or irritate the eye may occasionally be monitored rather than removed immediately. Any increase in tearing, squinting, discharge or surface damage should prompt reconsideration. Prognosis after complete surgical removal is generally excellent.
