Eye Disorders
This article begins a new two-part series on the importance and value of regular eye examinations for your Cavalier friends, explanations of various diseases and conditions which have been known to affect Cavaliers, and how to care properly for Cavalier eyes. Extra thanks for contributions from CKCSCC member Cornelia Tegart; my new friend Barbara Levy, whom I met through the internet, and who got Dr. B. Keith Collins, the chair of the ACVO Genetics Committee, which oversees CERF registrations, to send me material from the professional literature specific to Cavaliers; Dr. Michael Zigler, a veterinarian who practises in Oakville, Ontario, and who is maintaining his own page on the internet just dealing with eyes; Cynthia S. Cook, DVM, PhD, who took the time to provide information by e-mail; and Dr. Lionel F. Rubin, who conducted an eye clinic for the American Cavalier King Charles Spaniel Club, Inc. in May, 1995.
The Eye Examination
A detailed eye examination will be performed by a veterinary opthamologist (someone who has expertise in diseases and treatment of the eye). The pupils of the dog are dilated with eyedrops, and once the pupil is fully dilated, the vet will illuminate the eye to look for major problems. The different structures of the eye which are examined include the eyelids, globe as a whole, cornea, conjunctiva, sclera, anterior chamber, iris, lens, retina, choroid, and optic nerve.
A slit lamp biomicroscope is usually used next to examine the eyes in detail. This instrument will detect even minute abnormalities in the structures of the eyes. Before the exam is over, the retina is examined with an opthalmoscope, which provides a clear view of all the areas of the retina. An indirect opthalmoscope sits on vet's head, providing optics and a light source, while a focusing lens is held in the examiner's hand to visualize the retina. A CERF exam is conducted in the same manner as is described here, but it is done by veterinary opthamologists who are board certified by the American College of Veterinary Opthamologists and who records the observations on a CERF (Canine Eye Registry Foundation) form. Other veterinary opthamologists who are not board certified by the American College of Veterinary Opthamologists may have been board certified in their own countries, and may be seen to be equally qualified in conducting these exams and providing you with the findings.
There are differences between the normal eye structures of humans and of dogs. It is thought that dogs are near-sighted and have rather poor visual accommodation, which means they cannot see things sharply and in focus. They also do not have many specialized retinal cells which distinguish colours; they see black, white, various shades of gray, and perhaps some colour, but not nearly as much as primates, including humans, can. By the same token, dogs have larger pupils and wider visual fields than do people, and can see better in the dark. Due to their wide field of vision, dogs are quite adept at following moving objects. Dogs also have a third eyelid or haw (nictating membrane), which is an added protective device not found in humans. This third eyelid is capable of sweeping across the surface of the eye, thus cleaning and lubricating it.
First Group Of Eye Conditions
Corneal dystrophy(also known as corneal lipidosis) - Lipid (fat) deposits occur under the surface of the cornea when dogs are two-four years old. This is a condition which is thought to be inherited, probably with a polygenic mode of inheritance modified by environmental influences. These deposits appear as non-painful opaque whitish, silver, or gray blemishes, which usually occur bilaterally (affecting both eyes). They are usually seen in or around the centre of the eye. The opacities created by the deposits are non-inflammatory (not caused by an infectious process), are progressive on a variable basis, are not associated with systemic disease, and are NOT thought to impair vision. Occasionally they will regress in size or disappear, but there is no medical therapy available to reduce lipid deposition in the deeper layers of the cornea. The opacities are composed of a combination of calcium and/or lipids (cholesterol and others). Diet may contribute. Both males and females are affected.
Corneal ulcers - A corneal ulcer is a break in the outer layer (epithelium) of the cornea. It is dangerous and should be treated promptly. Large ulcers may be seen by the naked eye as dull spots or depressions on the surface of the cornea. Smaller ones are usually seen after the eye has been stained by fluorescein (an orange-red powder used to make dyes, which is used in solution applied topically to the eye to detect injury to the cornea). By definition, uncomplicated ulcers, while usually painful, should heal in three-four days with appropriate treatment (usually antibiotic ointment, but not one with cortisone’s in it, as the cortisone could delay healing and predispose to rupture of the eye) - check with your vet before administering treatment).
Ulcers that last longer than three-four days are usually seen to be complicated ulcers. There are two broad categories of reasons of why ulcers fail to heal. The first category is ulcers that fail to heal due to external causes. These external causes can include ongoing trauma due to other eye conditions such as entropion (the abnormal rolling in of the eyelid); or trichiasis (facial hair in contact with the eye as a result of facial conformation); or foreign bodies lurking behind the third eyelid, embedded within the eyelid, or within the cornea itself; or abnormally placed eyelashes. Also unresolved infections in the conjunctiva, glands of the eyelid margin, or within the tear duct may cause corneal ulceration. Unless these external causes are also treated, the corneal ulceration will not heal. The other category of why ulcers fail to heal deals with internal reasons, such as other eye diseases and primary tissue healing problems.
A number of diagnostic instruments and techniques are used to properly diagnose the reasons for a complicated corneal ulcer. It is important to note that if an ulcer becomes very deep, it will need to be treated quite aggressively in order to save the eye. As corneal ulcers are a frequent problem in veterinary medicine, you are encouraged to seek appropriate treatment rather than dismissing it.
Cataracts - A cataract is defined as an opacity of any size in the lens. The lens of the eye is usually clear or transparent, and focuses light rays on the retina. The opacity is usually white, but can have a yellowish or grayish appearance as well, and it scatters the light rays. The extent of the vision impairment is determined by the size and location of the cataract within the lens.
The word cataract means "to break down", and is used to apply to waterfalls and rapids as well as the lens. Changes in the lens due to cataracts may appear as small, insignificant dots, microscopic blisters, with a cracked-glass look, a diffuse haze, a "pearl-like" sheen, white streaks, or a completely white lens. A cataract usually starts small and progresses to include larger areas of the lens, but the rate of progression is difficult to predict. Cataracts may develop in one or both eyes. If a large portion of the lens becomes white, it prevents formed images from reaching the retina and blurred vision results. When a light is shined into the eye of a dog with a complete cataract, the dog sees only the white light and no images.
There is the possibility of two different forms of cataracts which have been identified in Cavaliers, with evidence of inheritance in both types. In the juvenile type, young adult dogs are affected. This type of cataract is bilateral, symmetrical, progressive, and becomes total.
The other form is congenital (present at and existing from the time of birth) and associated with micropthalmos (abnormal smallness of the eyeball). The cataract is bilateral, but not necessarily symmetrical, with the two eyes often being affected to different degrees. The more severe the micropthalmos, the more extensive the cataract. Other associated abnormalities of the lens seen in some Cavaliers with this type of cataract include lenticonus (the conical protrusion of the substance of the lens of the eye) and lentiglobus (exaggerated curvature of the lens of the eye, producing a spherical bulging).
During a two year period in the early 1980s, 144 Cavaliers were screened for eye problems in Sweden, and 11 cases of congenital ocular defects were found. Posterior lenticonus, cataracts, and micropthalmia were discovered in the affected dogs, most of which were interrelated. Of the 11 dogs with problems, cataracts were found in all cases, nine of which were bilateral and two of which were unilateral.
Senile (old age) cataracts are also common, as most dogs over eight years of age have some haziness in their lenses. Even when the lenses appear opaque, there may still be a considerable amount of useful vision left. Cataracts may also result from some injuries to the eye or internal diseases such as diabetes mellitus. However, inheritance is the major cause of cataracts in cats or dogs, and if a breeder knows that a tendency towards cataracts is in your lines, your breeding stock should be screened very carefully before being bred.
The only treatment for cataracts is surgical removal, and generally is only contemplated for dogs with severely impaired vision caused by mature cataracts in both eyes who are otherwise in good health. The biggest risk of surgery is the side effects of the anesthesia. Following surgery, the dog will not completely regain all vision, but will regain some vision.
Distichiasis and other eyelash abnormalities - When referring to people, the term distichiasis refers to a second row of eyelashes. Seeing as dogs usually do not have eyelashes on the lower lid, the term refers to extra lashes. The excessive lashes generally arise from the upper lids bilaterally. Severe distichiasis can be responsible for corneal ulceration in the upper portion. If these extra lashes are causing discomfort or more serious problems, medical intervention is warranted. Cryotherapy (therapeutic use of cold) or electrolysis is often successful, as is surgery. Plucking of the extra lashes may be done as well, although the benefit may be temporary and only last up to six months.
The term trichiasis refers to a third row of lashes and is used to describe misdirected lashes. Lashes which grow on the inside or outside of the eyelid are known as ectopic cilia. These abnormal lashes may even arise from the conjunctival surface, are usually short and stubby, and may cause extreme pain and profound squinting and tearing.
Macroblepharon - means excessively long eyelids, which expose large amounts of sclera (the whites of the eyes) around the cornea. The effect is to reduce the amount of protection the eyelids provide for the eyeball and to expose the eyeball to the environment and render it more vulnerable to any number of damaging conditions. Bradycephalic (flat-faced) breeds are more prone to being affected, and it may not occur until adulthood. Owners become concerned due to increased ocular redness caused by excessive exposure of the conjunctival surfaces (delicate membranes lining the eyelids and covering the eyeballs) due to the enlarged eyelid opening, or may complain about the poor cosmetic appearance due to the large amount of visible sclera. In the worst case scenario, the eyeball can roll forward out of the orbital socket. If this occurs, it is an emergency requiring veterinarian intervention.
Ankyloblepharon - This is the failure of one or both eyelids to open in young pups, and needs to be monitored by attentive breeders. Normally the eyelids of newborn pups will remain fused for about 10 to 15 days after birth, but then they will open completely. The danger of the eyelids not opening in the normal time span is the possibility of the pup developing a bacterial infection, most commonly with staphylococci, beneath the closed or partially closed eyelids. Pus which forms in response to the infection gathers under the eyelids, causing a bulging of the eyelid surface. Holding off on treatment could result in ulceration and scarring of the cornea, or even corneal perforation with subsequent loss of vision.
The breeder may apply warm, moist compresses at home and very gently attempt to separate the eyelids with the fingertips. An appropriate antibiotic should also be given. If these measures fail, surgery may be required to separate the eyelids and remove the pus.
Topics to be covered at that time include: Retinal Folds and Dysplasia; Progressive Retinal Atrophy; Tear-Staining; Blindness; and how owners can examine and take good care of their Cavalier's eyes.
Earlier this year, Cornelia Tegart had forwarded a page on Hereditary Eye Disorders in Cavaliers to our club secretary. All of the eye disorders mentioned on the page are discussed in detail in either this article or the next one coming out. The actual author is not named; however, some of the content bears repeating here.
"As a breeder you should be aware of the occurrences of these problems in your breeding program. The only way to do this is through opthalmic examination on a regular basis, starting from the whelping box. All progeny must be tested in order to have accurate information to plan a breeding program.
If one recognizes that with regard to heredity of genes all living things are either CLEAR, NORMAL/CARRIERS OR AFFECTED it becomes clear that testing of whole litters is the only way to be aware of those factors present in a brood bitch/stud dog. It is important to recognize also that wholesale disposal of dogs from breeding programs is not the answer, but is one area to be looked at objectively and seriously considered when breeding lines are compared.
It is essential that we all try to educate ourselves and produce Cavaliers who will live long and healthy lives. We must all do what we can to preserve the Cavalier as a valuable breed for generations to come. One way to do this is through a "wide eyed" approach wherein we personally do our best, encourage others to do their best and be totally honest toward that aim."
--------------------------------------------------------------------------------
Original Article Written by Myra Ehrman, RN,BA,BS,MScN on behalf of the Cavalier King Charles Spaniel Club Of Canada Health Education Committee
This article is not meant to replace veterinary advice. If you have any concerns about your dog's health, please seek proper medical care.
"Cavalier Quotes" is published by the Cavalier King Charles Spaniel Club of Canada for the entertainment and information of its members. All opinions expressed herein are those of the writers, and are not necessarily shared by the CKCSCC, its executive, or its members at large. Articles may be reproduced in other non-profil publications providing proper credit is given. The Editor would appreciate a copy of any publication using an original "Quotes" article.
Brian Chambers, Box 61, Milton, Ontario, Canada L9T 2Y3 Fax # 905-875-3066, e-mail glenking@globalserve.net
Peggy Wallace, 34 Erin Heights Drive, Erin, Ontario, Canada N0B 1T0, e-mail burbrook@gbd.com
The Eye Examination
A detailed eye examination will be performed by a veterinary opthamologist (someone who has expertise in diseases and treatment of the eye). The pupils of the dog are dilated with eyedrops, and once the pupil is fully dilated, the vet will illuminate the eye to look for major problems. The different structures of the eye which are examined include the eyelids, globe as a whole, cornea, conjunctiva, sclera, anterior chamber, iris, lens, retina, choroid, and optic nerve.
A slit lamp biomicroscope is usually used next to examine the eyes in detail. This instrument will detect even minute abnormalities in the structures of the eyes. Before the exam is over, the retina is examined with an opthalmoscope, which provides a clear view of all the areas of the retina. An indirect opthalmoscope sits on vet's head, providing optics and a light source, while a focusing lens is held in the examiner's hand to visualize the retina. A CERF exam is conducted in the same manner as is described here, but it is done by veterinary opthamologists who are board certified by the American College of Veterinary Opthamologists and who records the observations on a CERF (Canine Eye Registry Foundation) form. Other veterinary opthamologists who are not board certified by the American College of Veterinary Opthamologists may have been board certified in their own countries, and may be seen to be equally qualified in conducting these exams and providing you with the findings.
There are differences between the normal eye structures of humans and of dogs. It is thought that dogs are near-sighted and have rather poor visual accommodation, which means they cannot see things sharply and in focus. They also do not have many specialized retinal cells which distinguish colours; they see black, white, various shades of gray, and perhaps some colour, but not nearly as much as primates, including humans, can. By the same token, dogs have larger pupils and wider visual fields than do people, and can see better in the dark. Due to their wide field of vision, dogs are quite adept at following moving objects. Dogs also have a third eyelid or haw (nictating membrane), which is an added protective device not found in humans. This third eyelid is capable of sweeping across the surface of the eye, thus cleaning and lubricating it.
First Group Of Eye Conditions
Corneal dystrophy(also known as corneal lipidosis) - Lipid (fat) deposits occur under the surface of the cornea when dogs are two-four years old. This is a condition which is thought to be inherited, probably with a polygenic mode of inheritance modified by environmental influences. These deposits appear as non-painful opaque whitish, silver, or gray blemishes, which usually occur bilaterally (affecting both eyes). They are usually seen in or around the centre of the eye. The opacities created by the deposits are non-inflammatory (not caused by an infectious process), are progressive on a variable basis, are not associated with systemic disease, and are NOT thought to impair vision. Occasionally they will regress in size or disappear, but there is no medical therapy available to reduce lipid deposition in the deeper layers of the cornea. The opacities are composed of a combination of calcium and/or lipids (cholesterol and others). Diet may contribute. Both males and females are affected.
Corneal ulcers - A corneal ulcer is a break in the outer layer (epithelium) of the cornea. It is dangerous and should be treated promptly. Large ulcers may be seen by the naked eye as dull spots or depressions on the surface of the cornea. Smaller ones are usually seen after the eye has been stained by fluorescein (an orange-red powder used to make dyes, which is used in solution applied topically to the eye to detect injury to the cornea). By definition, uncomplicated ulcers, while usually painful, should heal in three-four days with appropriate treatment (usually antibiotic ointment, but not one with cortisone’s in it, as the cortisone could delay healing and predispose to rupture of the eye) - check with your vet before administering treatment).
Ulcers that last longer than three-four days are usually seen to be complicated ulcers. There are two broad categories of reasons of why ulcers fail to heal. The first category is ulcers that fail to heal due to external causes. These external causes can include ongoing trauma due to other eye conditions such as entropion (the abnormal rolling in of the eyelid); or trichiasis (facial hair in contact with the eye as a result of facial conformation); or foreign bodies lurking behind the third eyelid, embedded within the eyelid, or within the cornea itself; or abnormally placed eyelashes. Also unresolved infections in the conjunctiva, glands of the eyelid margin, or within the tear duct may cause corneal ulceration. Unless these external causes are also treated, the corneal ulceration will not heal. The other category of why ulcers fail to heal deals with internal reasons, such as other eye diseases and primary tissue healing problems.
A number of diagnostic instruments and techniques are used to properly diagnose the reasons for a complicated corneal ulcer. It is important to note that if an ulcer becomes very deep, it will need to be treated quite aggressively in order to save the eye. As corneal ulcers are a frequent problem in veterinary medicine, you are encouraged to seek appropriate treatment rather than dismissing it.
Cataracts - A cataract is defined as an opacity of any size in the lens. The lens of the eye is usually clear or transparent, and focuses light rays on the retina. The opacity is usually white, but can have a yellowish or grayish appearance as well, and it scatters the light rays. The extent of the vision impairment is determined by the size and location of the cataract within the lens.
The word cataract means "to break down", and is used to apply to waterfalls and rapids as well as the lens. Changes in the lens due to cataracts may appear as small, insignificant dots, microscopic blisters, with a cracked-glass look, a diffuse haze, a "pearl-like" sheen, white streaks, or a completely white lens. A cataract usually starts small and progresses to include larger areas of the lens, but the rate of progression is difficult to predict. Cataracts may develop in one or both eyes. If a large portion of the lens becomes white, it prevents formed images from reaching the retina and blurred vision results. When a light is shined into the eye of a dog with a complete cataract, the dog sees only the white light and no images.
There is the possibility of two different forms of cataracts which have been identified in Cavaliers, with evidence of inheritance in both types. In the juvenile type, young adult dogs are affected. This type of cataract is bilateral, symmetrical, progressive, and becomes total.
The other form is congenital (present at and existing from the time of birth) and associated with micropthalmos (abnormal smallness of the eyeball). The cataract is bilateral, but not necessarily symmetrical, with the two eyes often being affected to different degrees. The more severe the micropthalmos, the more extensive the cataract. Other associated abnormalities of the lens seen in some Cavaliers with this type of cataract include lenticonus (the conical protrusion of the substance of the lens of the eye) and lentiglobus (exaggerated curvature of the lens of the eye, producing a spherical bulging).
During a two year period in the early 1980s, 144 Cavaliers were screened for eye problems in Sweden, and 11 cases of congenital ocular defects were found. Posterior lenticonus, cataracts, and micropthalmia were discovered in the affected dogs, most of which were interrelated. Of the 11 dogs with problems, cataracts were found in all cases, nine of which were bilateral and two of which were unilateral.
Senile (old age) cataracts are also common, as most dogs over eight years of age have some haziness in their lenses. Even when the lenses appear opaque, there may still be a considerable amount of useful vision left. Cataracts may also result from some injuries to the eye or internal diseases such as diabetes mellitus. However, inheritance is the major cause of cataracts in cats or dogs, and if a breeder knows that a tendency towards cataracts is in your lines, your breeding stock should be screened very carefully before being bred.
The only treatment for cataracts is surgical removal, and generally is only contemplated for dogs with severely impaired vision caused by mature cataracts in both eyes who are otherwise in good health. The biggest risk of surgery is the side effects of the anesthesia. Following surgery, the dog will not completely regain all vision, but will regain some vision.
Distichiasis and other eyelash abnormalities - When referring to people, the term distichiasis refers to a second row of eyelashes. Seeing as dogs usually do not have eyelashes on the lower lid, the term refers to extra lashes. The excessive lashes generally arise from the upper lids bilaterally. Severe distichiasis can be responsible for corneal ulceration in the upper portion. If these extra lashes are causing discomfort or more serious problems, medical intervention is warranted. Cryotherapy (therapeutic use of cold) or electrolysis is often successful, as is surgery. Plucking of the extra lashes may be done as well, although the benefit may be temporary and only last up to six months.
The term trichiasis refers to a third row of lashes and is used to describe misdirected lashes. Lashes which grow on the inside or outside of the eyelid are known as ectopic cilia. These abnormal lashes may even arise from the conjunctival surface, are usually short and stubby, and may cause extreme pain and profound squinting and tearing.
Macroblepharon - means excessively long eyelids, which expose large amounts of sclera (the whites of the eyes) around the cornea. The effect is to reduce the amount of protection the eyelids provide for the eyeball and to expose the eyeball to the environment and render it more vulnerable to any number of damaging conditions. Bradycephalic (flat-faced) breeds are more prone to being affected, and it may not occur until adulthood. Owners become concerned due to increased ocular redness caused by excessive exposure of the conjunctival surfaces (delicate membranes lining the eyelids and covering the eyeballs) due to the enlarged eyelid opening, or may complain about the poor cosmetic appearance due to the large amount of visible sclera. In the worst case scenario, the eyeball can roll forward out of the orbital socket. If this occurs, it is an emergency requiring veterinarian intervention.
Ankyloblepharon - This is the failure of one or both eyelids to open in young pups, and needs to be monitored by attentive breeders. Normally the eyelids of newborn pups will remain fused for about 10 to 15 days after birth, but then they will open completely. The danger of the eyelids not opening in the normal time span is the possibility of the pup developing a bacterial infection, most commonly with staphylococci, beneath the closed or partially closed eyelids. Pus which forms in response to the infection gathers under the eyelids, causing a bulging of the eyelid surface. Holding off on treatment could result in ulceration and scarring of the cornea, or even corneal perforation with subsequent loss of vision.
The breeder may apply warm, moist compresses at home and very gently attempt to separate the eyelids with the fingertips. An appropriate antibiotic should also be given. If these measures fail, surgery may be required to separate the eyelids and remove the pus.
Topics to be covered at that time include: Retinal Folds and Dysplasia; Progressive Retinal Atrophy; Tear-Staining; Blindness; and how owners can examine and take good care of their Cavalier's eyes.
Earlier this year, Cornelia Tegart had forwarded a page on Hereditary Eye Disorders in Cavaliers to our club secretary. All of the eye disorders mentioned on the page are discussed in detail in either this article or the next one coming out. The actual author is not named; however, some of the content bears repeating here.
"As a breeder you should be aware of the occurrences of these problems in your breeding program. The only way to do this is through opthalmic examination on a regular basis, starting from the whelping box. All progeny must be tested in order to have accurate information to plan a breeding program.
If one recognizes that with regard to heredity of genes all living things are either CLEAR, NORMAL/CARRIERS OR AFFECTED it becomes clear that testing of whole litters is the only way to be aware of those factors present in a brood bitch/stud dog. It is important to recognize also that wholesale disposal of dogs from breeding programs is not the answer, but is one area to be looked at objectively and seriously considered when breeding lines are compared.
It is essential that we all try to educate ourselves and produce Cavaliers who will live long and healthy lives. We must all do what we can to preserve the Cavalier as a valuable breed for generations to come. One way to do this is through a "wide eyed" approach wherein we personally do our best, encourage others to do their best and be totally honest toward that aim."
--------------------------------------------------------------------------------
Original Article Written by Myra Ehrman, RN,BA,BS,MScN on behalf of the Cavalier King Charles Spaniel Club Of Canada Health Education Committee
This article is not meant to replace veterinary advice. If you have any concerns about your dog's health, please seek proper medical care.
"Cavalier Quotes" is published by the Cavalier King Charles Spaniel Club of Canada for the entertainment and information of its members. All opinions expressed herein are those of the writers, and are not necessarily shared by the CKCSCC, its executive, or its members at large. Articles may be reproduced in other non-profil publications providing proper credit is given. The Editor would appreciate a copy of any publication using an original "Quotes" article.
Brian Chambers, Box 61, Milton, Ontario, Canada L9T 2Y3 Fax # 905-875-3066, e-mail glenking@globalserve.net
Peggy Wallace, 34 Erin Heights Drive, Erin, Ontario, Canada N0B 1T0, e-mail burbrook@gbd.com
