Eye Disorders

By Linda Monroe

The Mastiff is, unfortunately, prone to many diseases and conditions involving the eyes which are hereditary problems. Very few Mastiffs are ever taken in for eye exams compared to the general population. It is scary to think of all of the problems that "have" been found in the ones that are tested.

The following is a list of diseases taken from the form used by the Canine Eye Registry Foundation (CERF). The ones with explanations are the problems found in Mastiffs and other large/giant breeds. The definitions and problems noted are listed in a book published by the American College of Veterinary Ophthalmologists titled "Ocular Disorders Proven or Suspected To Be Hereditary In Dogs". I have listed all of the defects that an ophthalmic exam covers and given definitions to those already found in Mastiffs.

Globe:

Eyelids:

Entropion - A conformational defect resulting in an "in-rolling" of one or more of the eyelids which may cause ocular irritation. It is likely that entropion is influenced by several genes (polygenic), defining the skin and other structures which make up the eyelids, the amount of weight of the skin covering the head and face, the orbital contents, and the conformation of the skull.

Ectropion - A conformational defect resulting in eversion (out-rolling) of the eyelids, which may cause ocular irritation due to exposure. Genetics same as Entropion.

Distichiasis - Eyelashes abnormally located in the eyelid margin which may cause ocular irritation. Distichiasis may occur at any time in the life of a dog.

Ectopic Cilia

Macroblepharon - Abnormally large eyelid opening; may lead to secondary conditions associated with corneal exposure.

Third Eyelid:

Gland Prolapse - Prolapse of the gland of the third eyelid. Protrusion of the tear gland associated with the third eyelid. The mode of inheritance of this disorder is unknown. The exposed glad may become irritated. Commonly referred to as "cherry eye".

Cartilage Anomaly/Eversion - A scroll-like curling of the cartilage of the third eyelid, usually everting the margin. This condition may occur in one or both eyes and may cause mild ocular irritation. The mode of inheritance is unknown.

Cornea:

Dystrophy - epithelial/stromal
Dystrophy - endothelial

Corneal Dystrophy - A non-inflammatory corneal opacity (white to gray) present in one or more of the corneal layers; usually inherited and bilateral. (Note: Can be acquired by feeding a high fat diet and excess cholesterol is deposited in the cornea. Linda)

Chronic Superficial Keratitis/Pannus - A bilateral disease of the cornea which usually starts as a grayish haze to the ventral or ventrolateral cornea, followed by the formation of a vascularized subepithelial growth that begins to spread toward the central cornea; pigmentation follows the vascularization. If severe, vision impairment occurs.

Exposure Keratopathy Syndrome - A corneal disease involving all or part of the cornea, resulting from a combination of contributing anatomic features including shallow orbits, excessive exophthalmia, macroblepharon and lagophthalmos.

Exophthalmia-protrusion of the eyeball - May result secondarily to failure to blink normally and exposure of the cornea.

Lagophthalmos-failure to close the eyelids completely - Results in exposure of the cornea and conjunctiva.

Dermoid

Uvea:

Iris Cysts - Pigmented cysts arise from the posterior pigmented epithelial cells of the iris and remain attached or break free, floating as pigmented spheres of various sizes and pigments in the anterior chamber. Some cysts tend to adhere to the posterior surface of the cornea. Rarely, cysts may be numerous enough to impair vision. The mode of inheritance is unknown.

Iris Coloboma

Persistant Pupillary Membranes - Persistant blood vessel remnants in the anterior chamber of the eye which fail to regress normally in the neonatal period. These strands may bridge from iris to iris, iris to cornea, iris to lens, or form sheets of tissue in the anterior chamber. The last three forms pose the greatest threat to vision and when severe, vision impairment or blindness may occur.

Lens: (*Cataracts)

Anterior Cortex
Posterior Cortex
Equatorial Cortex
Anterior Sutures
Posterior Sutures
Nucleus
(All of the above can be either diffuse, intermediate, or punctate).
Generalized
Subluxation/Luxation

*Cataracts - Lens opacity which may affect one or both eyes and may involve the lens partially or completely. In cases where cataracts are complete and affect both eyes, blindness results. The prudent approach is to assume cataracts to be hereditary except in cases known to be associated with trauma, other causes of ocular inflammation, specific metabolic diseases, persistant pupillary membranes, persistant hyaloid or nutritional deficiencies.

Vitreous:

Degeneration
Persistant Hyaloid Artery
PHPV - Persistant Hyperplastic Primary
Vitreous
PTVL - Persistant Tunica Vasculosa
Lentis

Fundus:

Retinal Atrophy - Generalized - Progressive Retinal Atrophy (PRA). A degenerative disease of the retinal visual cells which progresses to blindness. This abnormality may be detected by electroretinogram before it is apparent clinically. In all breeds, studied to date, PRA is recessively inherited.

Retinal Atrophy - Suspicious

Retinal Dysplasia - Abnormal development of the retina present at birth and recognized to have three forms:

1. Retinal Dysplasia/Folds: linear, triangular, curved or curvilinear foci of retinal folding that may be single or multiple.
2. Retinal Dysplasia/Geographic: any irregularly shaped area of abnormal retinal development, representing changes not accountable by simple folding.
3. Retinal Dysplasia/Detachment: either of the above described forms of retinal dysplasia associated with deparation (detachment) of the retina.

Choroidal Hypoplasia
Staphloma/Coloboma
Retinal Detachment
Retinal Hemorrage
Optic Nerve Coloboma
Optic Nerve Hypoplasia/Micropapilla

Other:

Glaucoma
Multiple Ocular Defects

Normal:

The really bad news is that most of these hereditary disorders are either recessive or polygenic. That means that two normal dogs bred together can produce problems. The key is to identify these carriers and not breed those two together again. In the case of serious disorders which affect vision or cause blindness, like PRA, even those dogs identified as carriers should be eliminated from all breeding programs, by spaying or neutering. All offspring of PRA dogs should also be spayed or neutered to eliminate this horrible disease from all breeds. A carrier may not produce PRA for years, and then meet up with another carrier, and bam, you have serious problems. The worst part is that all the other offspring of both parents along with their siblings and parents, may also be carriers. That's how serious problems become endemic in a breed. PRA may not show up until the dog is 3-5 years old, and usually they have been bred by then, and the problem is already wide spread. Just look at what's happened to Irish Setters and Golden Retrievers in just a few short years. Please, have your dogs tested by a CERF certified veterinarian before it's too late to save our beloved breed, the Mastiff.

Linda Monroe
Monarch Mastiffs