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Eye/Ear Issues
The material on this page is authored by Dorothy and Julian Prager

Eyes

Eye problems are potentially serious.  Minor problems can become major ones if not addressed.  See your Vet if the problem does not correct itself or with home remedy within a day.

To administer ointments to the eye, pull down the lower lid and place the ointment on the inner surface.  Then rub the eyelid gently over the eyeball to spread the medication.  Applying it directly to the eyeball can be dangerous if the dog jerks his head.  Eye drops can be placed directly on the eyeball.  Hold the eyelids open momentarily while the drops are applied.

    Eyelashes  --  Some Bulldogs develop a congenital condition in which extra eyelashes grow from the lid and rub against the cornea.   The irritation may range from hardly noticeable to very severe with heavy tearing.  The hair can be removed by plucking - it's not as hard as it sounds and the dogs adjust to it.  The condition may improve in time so treatment is no longer needed.

In severe cases, the hairs can be removed by electrolysis.  However, your dog will have to undergo general anesthesia, so the procedure is a serious one.  If left untreated, continued irritation of the eye in a severe case can lead to corneal scarring or blindness.

    Entropion and Ectropion  --  In the normal structure of the eye, the lid should be shaped like a globe.  It should not be rolled in or out.  Entropion is the condition where the eyelid rolls inward, causing irritation to the eye.  It is more common among Bulldogs than some other breeds.  If caused by a spasm or mechanical irritation, it can be corrected through medication.  If structural, the condition can be corrected by a simple operation.  Failure to correct the condition can lead to ulceration of the cornea and possible loss of sight.

Ectropion is a condition where it is rolled out, resulting in the third eyelid (or haw) being visible.  This is more common in Bulldogs than in some other breeds.   Its presence is undesirable in a show dog and a potential health problem because of the ease which foreign matter can enter the eye.

    Cherry Eye  --  This is created by an enlarged and prolapsed tear gland on the inner surface of the third eyelid, generally caused by infection.  It shows itself as a red, cherry-like growth protruding from the inner corner of the eye.  It usually occurs in puppies and young dogs.  It is more common among Bulldogs than some other breeds.  It is usually treated surgically.  This can be done by removal of the gland, with the need for only local anesthesia, or can be done by tacking the eyelid under general anesthesia.  The choice of procedures and alternatives should be discussed with your Vet.

    Dry Eye  --  This is a disease, usually of the older dog, which results from inadequate tear production, sometimes from the surgical treatment of Cherry Eye.   The eyes appear dull and listless and the eye has a thick discharge.  This can lead to infection or corneal ulcers if left untreated.  Fortunately, this is an easy disease to treat if not a severe case.  There are many artificial tear products in the drug store which can be used several times a day to relieve the condition.  In more severe cases, an an immunosuppressive drug can be used in the eye or an operation may be required to transplant the salivary duct to the eye to maintain the flow of fluid.

    Conjunctivitis  --  This is a common disease of all domestic animals (including humans, where "pink eye" is an infectious form).  Its cause can vary from an infection to allergies and environmental irritants.  Blinking and squinting caused by mild eye pain and tearing are the main symptoms you will notice.  Your Vet can diagnose the cause and prescribe appropriate medical treatment (sometimes eye drops or scraping the conjunctiva) to clear up the condition easily and rapidly.

    Corneal Problems  --  Corneal ulcers are dangerous and should receive immediate medical attention to avoid potential loss of the eye.  Large ones are visible with the naked eye as dull spots or depressions on the corneal surface.  Smaller ones can be seen under a special light after staining by the Vet.  Corneal abrasions are scratches which usually will heal in a day or two if no foreign body is present in the eye. The eye should be carefully checked to ensure removal of any foreign body present. Failure to act quickly can result in an ulcer or inflammation of the cornea.

Ears

    Genetics of Deafness in Dogs
    -- adapted from Dr. George M. Strain, Louisiana State University School of Veterinary Medicine,  Baton Rouge, Louisiana

Congenital deafness in dogs can be either acquired (i.e., caused by intrauterine infections, ototoxic drugs like gentamicin, liver disorders, or other toxic exposures before or soon after birth) or inherited.

Inherited deafness can be caused by a defect in a single gene locus or may involve multiple genes.  It is usually not possible to determine the cause of congenital deafness unless a clear problem has been observed in the breed or carefully planned breedings are performed.  Congenital deafness has been reported for approximately 40 breeds, Bulldogs among them.

It can potentially appear in any breed. The deafness has often been long-established in a breed but kept hidden from outsiders to protect reputations.  The disorder is usually associated with pigmentation patterns, where increasing amounts of white in the hair coat increase the likelihood of deafness.  Two pigmentation genes in particular are often associated with deafness in dogs: the merle gene (not found in Bulldogs, but seen in the Collie, Shetland Sheepdog, Dappled Dachshund, Harlequin Great Dane, American Foxhound, Old English Sheepdog, Norwegian Dunkerhound among others) and the piebald gene (found in the Bulldog and Bullterrier, Samoyed, Greyhound, Great Pyrenees, Sealyham Terrier, Beagle, Dalmatian, and English Setter).  Not all breeds with these genes have been reported to be affected.

The deafness, which usually develops in the first few weeks after birth while the ear canal is still closed, normally results from the degeneration of part of the blood supply to the cochlea.  The nerve cells of the cochlea subsequently die and permanent deafness results.  The cause of the vascular degeneration is not known, but appears to be associated with the absence of pigment producing cells (melanocytes) in the blood vessels.  The function of these cells is not known but appears to be critical for survival of the cells supplying blood to the cochlea.

Deafness may also occur later in life from causes such as toxicities, infections, or injuries: these forms of deafness almost never have a genetic cause in animals and thus do not present a concern in breeding decisions.

The incidence of congenital deafness in different breeds is seldom known because of the limited number of studies. In the Dalmatian, where the incidence is highest, 8% of all dogs are bilaterally deaf and 22% are unilaterally deaf.  The incidence of all types of deafness in the general dog population is low, reported to be 2.56 to 6.5 cases per 10,000 dogs seen at veterinary school teaching hospitals.  Recognition of affected cases is often difficult because unilaterally deaf dogs appear to hear normally unless a special test (the brainstem auditory evoked response, BAER) is performed; facilities to perform the BAER are usually only available at veterinary schools.  A unilaterally deaf dog can be as great a genetic risk for transmission of deafness to its offspring as is a bilaterally deaf dog.

The method of genetic transmission of deafness in dogs is usually not known.  There are no recognized forms of sex-linked deafness in dogs, although this does occur in humans.  The disorder has been reported to have an autosomal recessive mechanism in the Rottweiler, Bullterrier, and Pointer.  References usually state that deafness transmission in most other breeds is autosomal dominant, but there is reason to believe that this is not always true.  Pigment associated inherited deafness is not restricted to dogs -- similar defects have been reported for mice, mink, pigs, horses, cattle, cats, and humans.

Blue eyes resulting from an absence of pigment in the iris, is common with pigment-associated deafness, but is not in and of itself an indication of deafness or the presence of a deafness gene.  In humans, deafness is sometimes associated with a complex of symptoms within an autosomal dominant disorder with incomplete penetrance -- which means that individuals that inherit the disorder may not show all components of the syndrome - i.e., they may not be deaf.   Incomplete  penetrance of a defect greatly complicates the determination of mode of inheritance. At present there is no documentation that incomplete penetrance is a factor in any canine deafness.

In simple Mendelian genetics, each dog carries two copies of each gene, one from each parent. The possible outcomes of breedings can be demonstrated with tables showing the genotype of both parents and the possible combinations of their offspring.  If deafness is carried as a simple autosomal recessive gene (d), the breeding of two carriers (Dd) will result in 25% of the pups showing the disease (dd), 25% free of the defect (DD) and 50% carriers of the disease (Dd).  The breeding of a carrier to a dog free of the defect will result in no affected dog, 50% free and 50% carriers.  Finally the breeding of an affected dog to a dog free of the defect will result in 100% carriers and no affected or free.

If instead deafness is carried as a simple autosomal dominant gene (D), the breeding of an affected dog (Dd) to a free dog (dd) would result on average in 50% affected and 50% free.  Dogs with the genotype DD would be unlikely to occur unless two deaf dogs had been bred.  All of the above assumes that incomplete penetrance is not acting.  If more than, one gene (recessive and/or dominant) is involved in producing deafness, the possible combinations become much more  complicated.  It is estimated for humans that there are 10-15 different autosomal recessive deafness genes, so that children of two deaf parents can be unaffected but carry both genes.  If deafness in dogs results from more than one recessive gene, the possible outcomes of breedings are more numerous and determination of the mechanisms of  transmission will be difficult.

As stated above, deafness is often associated with the merle (dapple) gene, which produces a mingled or patchwork combination of dark and light areas. This gene (M) is dominant, so that affected dogs (Mm) show the pattern which is desirable in many breeds. However, when two dogs with merle are bred, 25% will end up with (MM) genotype.  These dogs have a solid white coat and blue irises, are often deaf and/or blind and are sterile.  Breeders of these dogs know not to breed merle to merle. In this case the deafness is neither dominant nor recessive, but is linked to a dominant gene that disrupts pigmentation and secondarily produces deaf dogs.

Genetic transmission of deafness in dogs with the piebald (Sp) and extreme piebald (Sw) pigment genes, such as the Bulldog, is less clear.  These genes affect the amount and distribution of white areas on the body.  Deafness in Dals does not appear to be a simple recessive disorder: we have twice bred pairs of deaf Dals and obtained mostly hearing puppies, when all should have been deaf if it was recessive.  These findings might be explained by a multi-gene cause, the presence of two different autosomal recessive genes, or a syndrome of incomplete penetrance.  Further studies will be required to determine the mechanisms.

So what should breeders do when deafness crops up?  The most conservative approach would be not to breed the affected animal and not repeat the breeding that produced deafness.  As a general rule bilaterally deaf puppies  make poor pets, are prone to biting, frequently die from misadventure (cars), and require excessive care. 

Unilaterally deaf dogs can make good pets but usually should not be bred.  When deafness is uncommon in a breed, affected dogs should not be bred, but this does not mean that all related dogs are a risk and must be retired from breeding.  An understanding of simple autosomal recessive and dominant patterns, as explained above, can allow the breeder to make informed decisions and likely avoid future deaf animals without sacrificing a breeding line that has been shaped over many years.  However, extreme caution must be used when line breeding of dogs related to deaf dogs, whether the deafness is unilateral or bilateral.  To make these decisions in an informed manner for breeds with known deafness, it is important that advantage be taken of hearing testing facilities at veterinary schools. Unilaterally deaf dogs cannot be detected by other means, and these dogs will pass on their deafness genes. 

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