Page 573 - ONLINE PROCEEDING BOOK WSAVA 2017
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WSVA7-0434
FECAVA SYMPOSIUM: HEREDITARY DISEASES
HEREDITARY EYE DISEASES
E.O. Ropstad1
1Norwegian University of Life Sciences, Fac of Veterinary Medicine and Biosciences, Oslo, Norway
INHERITED EYE DISEASES IN DOGS AND CATS
Ernst-Otto Ropstad, DVM, PhD, Dip ECVO
Norwegian University of Life Sciences, Faculty of Veterinary Medicine and Biosciences
Inherited eye diseases comprise both congenital and developmental conditions where the clinical symptoms become apparent later in life. The cutoff point for congenital eye diseases has been set to 8 weeks of age (ref www.ECVO.org).
Although not comprehensive, a few highlights of inherited eye diseases in the dog and cat are described below.
Eyelids
Microblepharon/blepharophimosis: relatively small eyelids/eyelid openings. Usually in conjunction with a too small eyeball (microphthalmia/cystic eye/ anophthalmia). Usually no treatment needed, but if necessary; surgical enlargement of the eyelid openings.
Coloboma: Parts of/entire eyelid(s) not developed. Seen in all breeds of dogs and in cats, most commonly Himalayan. Usually affects lateral aspect of upper eyelid. Often leads to irritation/pain because of hairs rubbing the cornea/conjunctiva (trichiasis) in addition to repeated secondary conjunctivitis.
Dermoid: Normal tissue in an abnormal location. Usually excessive skin/ hair on the eyelids. Surgery is indicated if it causes irritation/recurrent infections/ malfunctioning of the eyelid. Surgical techniques vary with extent/location. Dermoids can also affect the conjunctiva and/or cornea.
Entropion: Inverted eyelids. Can lead to trichiasis/ irritation/ recurrent secondary infections/ corneal ulcers/ pigmentary keratitis. Can be primary (inherited) or secondary. Spastic entropion is excluded by relief of the condition after application of topical anesthetic. Several surgical techniques exist.
Ectropion: Everted eyelids. Usually affects lower eyelid. Affects mainly dogs. Surgical intervention is indicated if recurrent secondary infections/irritates the dog. Several surgical techniques described.
Euryblepharon: Too large eyelids/eyelid openings. Most common in large breed dogs with “diamond eyes”. Usually en-and ectropion simultaneously. Requires surgical intervention if recurrent secondary infections/
trichaisis/ corneal affection. Various surgical techniques described. Important to stabilize the lateral canthus.
Distichiasis/Ectopic cilia: Distichiasis are hairs exiting the Meibomian gland openings along the eyelid margins. Ectopic cilia are hairs originating from hair follicles close to the Meibomian glands, exiting the conjunctiva. These usually causes acute ocular pain/blepharospasm. The hairs are usually located in the central part of the upper eyelid.
Tear canal and tear glands
Aplasia/hypoplasia of the tear canals/canuliculi:
Symptoms are excessive tearing usually without
any signs ocular discomfort. Secondary infections occur. Aplasia of the lower tear canal opening is the most common, sometimes accompanied with a subconjunctival swelling underneath the conjunctival surface in the anatomical area of the opening. Problems further down in the tear canals are less prevalent. Eventual treatment consists in surgical opening of the tear canals. Diagnostic imaging with or without contrast is advisable for is advisable if there is a suspicion of locations other than the openings. Dermoids/foreign bodies/ neoplasias etc are differentials.
Aplasia/hypoplasia of the tear glands: Dogs and
cats normally possess two tear glands for each eye
(the orbital( principal) and the tear gland of the third
eyelid ( accessory). These glands are responsible for the production of the watery part of the tear  lm, and aplasia/ hypoplasia will lead to no/ insuf cient production, with consequent symptoms of dry eye (kerato conjunctivitis sicca (KCS). The diagnosis is made by schirmer tear test (STT), often accompanied by mucoid/ mucopurulent discharge, corneal  brosis/neovascularization/ pigmentation etc. Lower values than normal (15-25 mm) are indicative of KCS. Borderline measurements should be con rmed by repeating measurements at recheck. Inherited neurogenic KCS often is evident early in life, can be unilateral or bilateral, often accompanied by ipsilateral dry nostrils and/ or oral cavity. Several dog breeds are genetically predisposed to immune mediated KCS later
in life. Other etiological causes (drug induced/toxic/ neoplasia/endocrine/trauma/ infectious etc) have to be ruled out before the de nite diagnosis of inherited KCS can be made.
Nanophthalmia/microphthalmia/anophthalmia:
Nanophthalmia is a functional eyebulb of a smaller
size than normal, without any other abnormalities. A microphthalmic eye is smaller than normal accompanied by other developmental conditions such as micro cornea, anterior segment dysgenesis, lens abnormalities in addition to retinal and optic nerve abnormalities.
A microphthalmic eye can be visual or non-visual.
An Urban Experience
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