Eye Conditions in the Bedlington Terrier

Cynthia S. Cook, DVM, PhD

Diplomate, American College of Veterinary Ophthalmologists

Many conditions which affect the eye are thought to be inherited and important for breeders to recognize in a conscientious breeding program. Other eye conditions may not have a genetic origin but may affect vision and/or comfort. An examination by a veterinary ophthalmologist is the only means of identifying many of these diseases. An eye examination is quick, painless and inexpensive. It is performed without sedation and is often available through screening clinics at many dog shows. Annual eye examination is recommended so that early detection may reduce the incidence of these conditions in the population of animals used for breeding. The Canine Eye Registration Foundation (CERF) maintains a registry of animals which are examined and reported. They also publish a book (Ocular Disorders Presumed to be Inherited in Purebred Dogs*) which includes a discussion of how inherited conditions are identified and a detailed glossary with definitions of clinical terms. During the five year period 1991-1995, a total of 183 eye examinations were performed on Bedlingtons. This is contrasted with 1218 Bedlingtons registered with AKC during the five years (1990-1994). Thus, only approximately 15% of our Bedlington terriers are being examined.

The following is a description of the eye conditions which are more commonly seen. The table which provides more detailed information specific to Bedlingtons.

• Microphthalmia: simply means "small eye". This condition is congenital (present at birth) and is nearly always associated with other malformations of the eye including cataract and retinal dysplasia which result in blindness. Microphthalmia occurs rarely; one or both eyes may be affected.
• Distichiasis: extra eyelashes which are located inside the normal row of lashes; they emerge from the openings of the meibomian glands (see diagram). This condition is very common in the Bedlington. Usually the upper and lower eyelids of both eyes are affected. The lashes are typically very numerous and soft, resting on the tear film covering the eye without causing significant irritation. Occasionally tearing may be noted but this is more often due to imperforate nasolacrimal puncta (see below).
• Entropion: "inrolling" of the eyelid margin so that hair is contacting the cornea. This condition is very painful and, if untreated, may result in blindness.
• Imperforate nasolacrimal puncta: failure of normal development of the opening which allows drainage of the tears away from the eye (see diagram). One or both eyes may be affected either partially or completely. This condition is very common in the Bedlington and results in tearing and staining of the hair below the eyes.
• Dry eye (keratoconjunctivitis sicca): insufficient production of tears due to degeneration of the tear gland; both eyes are usually affected. The test for this condition is the Schirmer tear test which is not part of a routine screening (CERF) eye examination but is indicated when clinical signs of a thick ocular discharge and/or recurrent eye infections are present.
• Glaucoma: elevated pressure inside the eye. This occurs because the fluid which is normally constantly produced within the eye (in the ciliary body) cannot exit the eye through the iridocorneal angle (see diagram). Diagnosis of glaucoma requires a test called tonometry which is not part of a routine screening (CERF) eye examination. Although only one eye may be affected initially, the condition is often ultimately bilateral. Gonioscopy is a specialized examination of the iridocorneal angle which can determine if an eye with normal pressure is predisposed to developing glaucoma.
• Cataract: any opacity in the lens or capsule. One or both eyes may be affected. In the Bedlington, these opacities are often small and non-progressive. Thus, they do not affect vision and may go undetected unless a thorough examination is performed by a veterinary ophthalmologist. Unknowingly breeding affected animals is highly likely to lead to an increased incidence of cataracts.
• Retinal Dysplasia: abnormal development of the retina, present at birth; non-progressive and generally recognized to have three forms: folds, geographic, and detached. The genetic relationship between the three forms of this disease is not known for the Bedlington. The condition was originally described in the Bedlington in 1963 and its incidence since then has been reduced but not eliminated.

• ·Folds: linear, triangular, curved or curvilinear areas of retinal folding that may be single or multiple. When seen in puppies, this condition may partially or completely resolve with maturity. Its significance to vision is unknown. The genetic relationship between folds and the more severe forms of retinal dysplasia is undetermined.
• ·Geographic: any irregularly-shaped area of abnormal retinal development containing areas of thinning, elevation representing folds, and retinal disorganization. This form may be associated with impairment of vision.
• ·Detached: severe retinal disorganization associated with separation (detachment) of the retina and blindness.

• Progressive Retinal Atrophy (PRA): a degenerative disease of the retinal visual cells which progresses to blindness. The rod photoreceptors which are responsible for dim light vision are affected first. This condition may be detected by a specialized test called an electroretinogram (ERG) before it is apparent clinically. PRA occurs rarely in the Bedlington.

Table summarizing these eye defects and their effect on vision

In addition, Veterinary Vision has a web site which gives additional information on eye abnormalities.

*The book (Ocular Disorders Presumed to be Inherited in Purebred Dogs) and statistical information on reported eye examinations is available from CERF: Purdue University SCC-A, West Lafayette, IN 47907, (765) 494-8179.

©1998