Entropion - Sheep
Entropion is a common congenital disorder in lambs and is usually characterised by the turning in of one or both lower eyelids. In-turned hairs rub on the cornea and cause severe irritation. The condition is seen in most breeds of British sheep and is probably inherited, although the nature of the inheritance is unknown.
Secondary or cicatritial entropion can also occur due to previous injury.
The condition is painful and affected animals show signs such as: blepharospasm and epiphora.
Untreated severe cases can progress to corneal ulceration with additional secondary spastic entropion.
Bilaterally affected animals can go blind due to corneal granulation tissue, corneal perforation and endophthalmitis. Blind animals may also die of starvation.
Diagnosis of the condition is made on the basis of clinical signs and the observation of turned in eyelids.
The condition is usually only detected once animals start showing signs of pain and irritation.
Fluorescein can be used to demonstrate the presence of corneal ulcers.
Lambs with entropion should not become part of the future breeding stock and rams that produce entropion lambs should not be kept for breeding.
Topical antibiotics should be used in all cases to reduce the incidence of secondary infection.
Many techniques are available for the treatment of primary entropion in lambs. The aim of treatment is that it is simple, cost effective and curative.
Manual eversion: can work in mild cases. Eyelids should be dried and a fold of eyelid skin close to the eyelid margin should be pressed briefly and firmly between finger and thumb. This should be repeated several times a day, and a topical lubricant can be applied to protect the cornea.
Traction sutures or clips: can also be used by placing vertical mattress sutures or clips to evert the affected eyelid. This can be used when many lambs are affected, and the sutures are allowed to slough off several weeks later.
Injection technique: for economic reasons, the condition has sometimes been treated by injection of a liquid to physically alter lid alignment. Injection of procain penicillin or tetracycline has been described. The use of paraffin causes a granulomatous response and should be avoided. Manual eversion and stapling are preferred to this technique.
Surgery: non-responsive entropion or entropion in a valuable animal can be treated with surgical removal of a strip of skin and muscle from under the eyelid, a modified Holz-Celsus technique.
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Gelatt, K. (2000) Essentials of veterinary ophthalmology, Wiley-Blackwell
Maggs, D., Miller, P. (2008) Slatter's fundamentals of veterinary ophthalmology, Elsevier Health Sciences
Stades, F., Wyman, M. (2007) Ophthalmology for the veterinary practitioner, Wiley-Blackwell
Crispin, S. (2005) Notes on veterinary ophthalmology, Wiley-Blackwell
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