Corneal dystrophy in dogs: causes, symptoms and treatment options

Introduction to corneal dystrophy

Corneal dystrophy is a rare but often serious disease that primarily affects dogs. This is a disease of the cornea that is often genetically determined. The affected animals show changes in the cornea that can lead to visual impairment and, in severe cases, complete blindness. This disorder usually occurs without warning and is not the result of injury or infection.

Corneal dystrophy doesn't just affect dogs; It can also occur in people and other animals. However, it is more common in dogs, particularly in certain breeds such as the Collie, Siberian Husky and Shetland Sheepdog. This genetic predisposition makes research on corneal dystrophies even more important.

Corneal dystrophy
Corneal dystrophy 2

Causes of corneal dystrophy

Corneal dystrophy often has genetic causes. It is caused by incorrect cell regeneration or abnormal protein deposits in the cornea. The exact cause often varies from breed to breed and requires specific investigations.

  1. Genetics : Certain dog breeds have a higher risk of developing corneal dystrophy. This genetic predisposition is often inherited in a dominant manner, so that just one affected parent is enough to pass on the disease.
  2. Cellular metabolism disorders : Some forms of corneal dystrophy result from defective lipid or glycoprotein production, which leads to the accumulation of these substances in the cornea. These deposits disrupt light transmission and cause vision problems.
  3. Changes in the immune system : In rare cases, dysregulation of the immune system is discussed as a possible cause, especially when no genetic predisposition can be identified.

Corneadystrophy in older Weimaraners

Corneal dystrophy in older Weimaraners is a complex, genetic eye disease that can occur more frequently due to the specific genetic predisposition of this breed and aging-related factors. Weimaraners are one of several dog breeds in which genetic eye diseases are more common, and in older animals, signs often only become apparent at an advanced stage. Below we delve deeper into the genetic aspects of this disease.

1. Genetic basis of corneal dystrophy

Corneal dystrophy, a hereditary disease, often results from recessively inherited mutations in genes involved in the structure and function of the corneal layers. These mutations can cause different symptoms and disease progression depending on the layer of the cornea affected:

  • Epithelial dystrophies : Mutations in genes responsible for proteins in the superficial layer of the cornea lead to abnormalities, most often manifested by superficial corneal damage and sensitivity to light.
  • Stromal dystrophies : Genetic defects in the collagen fiber or glycosaminoglycan-producing genes can lead to deposition of lipids or crystals. This often causes a milky cloudiness in the central area of ​​the cornea.
  • Endothelial Dystrophies : The deepest layer of the cornea, the endothelium, is often affected by genetic abnormalities in Weimaraners, resulting in endothelial dystrophy. This variant is particularly serious because the endothelial cells are responsible for maintaining fluid balance in the cornea. If these cells are dysfunctional, water accumulation and thickening of the cornea can occur, which severely impairs vision.

2. Age-dependent genetic manifestation in Weimaraners

Age plays an important role in the manifestation of genetic eye diseases. Weimaraners who are genetically predisposed to corneal dystrophy often show the first symptoms in the middle to late years of life (from around seven to nine years). With age, the ability of cells to regenerate decreases, and degenerative processes in the cornea accelerate the development of genetic defects.

This is particularly significant in Weimaraners, as their ability to maintain corneal fluid balance deteriorates due to progressive endothelial dystrophy caused by genetic changes. This leads to excessive fluid intake (corneal edema), which clouds the cornea and severely limits vision.

3. Frequency and inheritance patterns in Weimaraners

Research shows that certain eye diseases are more common in Weimaraners and similar breeds (e.g. Siberian Huskies, Boston Terriers). Genetic analyzes have shown that corneal dystrophy is often inherited in an autosomal recessive manner, meaning that both parents must carry the mutated gene to cause the disease in the offspring. In Weimaraners with an increased susceptibility to endothelial dystrophies, it is assumed that at least one autosomal dominant inheritance pattern is involved, which increases the susceptibility to corneal edema in old age.

Breeders often use genetic screening methods to minimize the risk by eliminating Weimaraners from breeding that carry known mutations. In older animals that have already developed the disease, the genetic profile plays a crucial role in determining the course of the disease and therapeutic approaches.

4. Possible genetic testing and prevention strategies

Genetic testing is helpful in reducing the prevalence of genetic corneal dystrophies in Weimaraners. Specific DNA tests can help identify carrier genes in the parent animals. By analyzing certain genetic markers, breeders can determine whether an animal is at risk of passing on its genetic predisposition to its offspring.

For Weimaraners affected by endothelial dystrophy, some testing laboratories now offer special genetic tests that can detect markers for corneal dystrophies. The use of such tests in breeding can significantly reduce the risk of developing these diseases in future generations.

5. Relationship between genetic predisposition and environmental factors

Although corneal dystrophy has a strong genetic basis, environmental factors such as diet and care can influence its course. For genetically predisposed Weimaraners, it is advisable to check their eyes regularly and reduce factors such as UV radiation that could put additional strain on the cornea. Dietary measures containing antioxidants and essential fatty acids can positively influence disease progression by supporting cellular health.

Corneal dystrophy in older Weimaraners is a prime example of how genetic predisposition and age-related factors can interact. By better understanding the genetic mechanisms and using modern testing techniques, breeders and veterinarians can help reduce the risk of this disease and provide affected animals with a higher quality of life.

Symptoms

The symptoms of corneal dystrophy in dogs, especially in genetically predisposed breeds such as the Weimaraner, are varied and depend largely on the specific form and severity of the disease. This disease affects the cornea of ​​the eye and can manifest itself in different layers - the epithelium, stroma or endothelium - each causing different symptoms. A comprehensive overview of the most common symptoms of corneal dystrophy should help identify signs early and improve the affected dog's quality of life.

1. General symptoms of corneal dystrophy

  • Corneal clouding : The most common and earliest abnormality in dogs with corneal dystrophy is corneal clouding. This often manifests itself as a whitish-gray haze that initially appears in the middle of the cornea or at its edges and becomes denser and more extensive over time.
  • Loss of visual acuity : As the clouding of the cornea progresses, there is a significant loss of visual acuity. Dogs appear more insecure in their surroundings and may have difficulty finding their way in unfamiliar environments.
  • “Seeking Vision” Behavior : Dogs with reduced vision may exhibit behaviors that indicate orientation difficulties, such as bumping into furniture, difficulty finding toys, or difficulty recognizing people and animals from a distance.
  • Eye pain and eye rubbing : In some cases, corneal dystrophy can cause irritation and pain. Dogs then often rub their eyes on furniture or with their paws, increasing the risk of additional infection or injury to the cornea.

2. Specific symptoms depending on the form of corneal dystrophy

Corneal dystrophy can occur in three main forms – epithelial dystrophy, stromal dystrophy and endothelial dystrophy. Each form has specific symptoms that are caused by the layer of the cornea affected.

Epithelial dystrophy

Epithelial dystrophy affects the outer layer of the cornea and can manifest as smaller erosions and microscopic blisters that are often difficult to detect at first. Common symptoms include:

  • Increased sensitivity to light : Dogs often have a strong reaction to bright light and may avoid sunny places or bright rooms because the bright light causes discomfort.
  • Microerosions and corneal defects : Fine, barely visible microerosions can occur in the outer layer of the cornea. These small damages increase susceptibility to bacterial infections and increase eye irritation.
  • Tear flow : Increased tear flow is another typical sign as the body tries to protect and lubricate the damaged cornea.

Stromal dystrophy

Stromal dystrophy affects the middle layers of the cornea and is manifested by the accumulation of lipids or crystals that can produce a milky-white color. Symptoms of this form include:

  • Milky, diffuse opacity : The cornea shows a diffuse, usually whitish-gray color. This clouding is often visible in the middle of the cornea and gradually spreads, significantly affecting the dog's visual acuity.
  • Bilateral appearance : Stromal dystrophy often occurs in both eyes at the same time and is symmetrical, making it easier to diagnose and recognize the genetic component.
  • Difficulty in poor lighting : Because haze scatters incoming light in the cornea, dogs often have more difficulty at dusk or night when the light is dimmer.
  • Slow progression : Compared to other forms of corneal dystrophy, stromal dystrophy tends to progress more slowly and is less likely to result in complete blindness. Symptoms often develop over months to years.

Endothelial dystrophy

Endothelial dystrophy affects the deepest layer of the cornea and is the most serious form of corneal dystrophy. It leads to an accumulation of fluid in the cornea and is often progressive and irreversible. Symptoms include:

  • Severe corneal edema : In endothelial dystrophy, the endothelium fails to regulate water balance in the cornea, resulting in significant accumulation of fluid and thickening of the cornea. This manifests itself in a gray-blue shimmer.
  • Blistering (bullae) : The fluid often collects in small bubbles (bullae) that can burst under strong pressure or friction. This causes additional irritation and pain and can make the cornea more susceptible to infection.
  • Significant loss of vision and orientation : Dogs with advanced endothelial dystrophy often lose their ability to orient themselves easily because the cornea no longer allows light rays to pass through correctly. This often leads to complete blindness.
  • Pain and redness : The accumulation of water in the cornea can cause irritation and an inflammatory reaction, evident by redness and pain in the eye. Dogs blink frequently and avoid opening their eyes wide.

3. Behavioral changes in affected dogs

In addition to the purely physical symptoms, behavioral changes are also a typical sign of progressive corneal dystrophy. These usually result from the increasing loss of vision and the associated uncertainty:

  • More cautious behavior : Many dogs exhibit more reserved behavior and move more slowly, especially when in unfamiliar environments. They often avoid approaching furniture or narrow paths because they are unsteady.
  • Increased dependence on the owner : Due to limited visibility, affected dogs rely more heavily on their owners and follow them more often. They are looking for direct proximity and guidance.
  • Increased anxiety and nervousness : Vision loss often leads to increased nervousness, especially around loud noises or in new situations. Dogs with corneal dystrophy may become more restless and bark or whine more.
  • Avoidance of activities : Dogs with severe visual impairments tend to play or frolic less. Instead, they often withdraw or lie still in one place because they do not feel safe.

4. Recognizing the first symptoms in older Weimaraners

Since Weimaraners are genetically susceptible to various eye diseases, it is particularly important to recognize the first symptoms of corneal dystrophy early on. Regular ophthalmological examinations for older animals (from around 7 years of age) can help diagnose the disease early and slow its progression through supportive measures. Early symptoms such as mild cloudiness, increased tearing, or avoidance of bright light should be taken seriously to improve the dog's quality of life in the long term.

Corneal dystrophy is a serious, genetic disease that can occur as dogs age, particularly in genetically susceptible breeds such as Weimaraners. Symptoms range from mild clouding and increased sensitivity to light to severe visual impairment and complete blindness. Early detection and regular examinations cannot prevent the progression of the disease, but it can potentially slow it down, which can significantly improve the affected dog's quality of life.

Causes of corneal dystrophy

Causes of Corneal Dystrophy in Dogs

An overview of the most common genetic and environmental influences

Genetic predisposition

Certain dog breeds such as Weimaraners, Collies and Huskies have a higher genetic susceptibility to corneal dystrophy. This predisposition is often inherited in an autosomal recessive manner, with both parents having to carry the gene.

Cell metabolism disorders

In some dogs, genetic defects cause disruptions in corneal cell metabolism, resulting in abnormalities in the production of lipids and proteins. These substances accumulate and cause cloudiness.

Changes in the immune system

In rare cases, immunological factors can be the cause. Dysregulation of the immune system may contribute to corneal dystrophy, especially if no genetic predisposition is identified.

Aging processes

In older dogs, the cell regeneration of the cornea deteriorates, increasing the susceptibility to deposits and cloudiness. This age-related weakening can further exacerbate genetic defects.

Racial predisposition

Some breeds are more severely affected because genetic defects have become entrenched over generations. These include Boston Terriers and Siberian Huskies, among others, where the disease occurs more frequently.

diagnosis

The diagnosis and differential diagnosis of corneal dystrophy in dogs requires a thorough examination of the cornea and differentiation from other possible causes of corneal opacities and vision loss. Since the symptoms of corneal dystrophy - such as clouding and visual impairment - can also occur in other eye diseases, a differentiated diagnosis is crucial in order to make an exact diagnosis and initiate the appropriate therapy.

1. Diagnostic procedure for corneal dystrophy

The diagnosis of corneal dystrophy involves various examination methods, including both clinical examination and special imaging techniques.

Clinical examination

The first diagnostic measure is a thorough examination of the eye and especially the cornea by a specialized veterinarian or veterinary ophthalmologist. The most important steps are:

  • Visual inspection of the cornea : On examination, the cornea typically shows white to gray opacities that are layer dependent and usually appear symmetrically in both eyes.
  • Slit lamp examination : A detailed examination of the cornea with a slit lamp allows the precise determination of the affected layer of the cornea (epithelium, stroma or endothelium). This examination is particularly valuable because each form of corneal dystrophy affects different layers of the cornea and the type of opacification differs.

Fluorescein test

The fluorescein test is used to visualize superficial injuries or erosions of the cornea. This involves applying a fluorescent dye to the eye:

  • Test procedure : The dye adheres to damaged cells in the cornea, making erosions or micro-defects visible. A negative fluorescein test is typical for corneal dystrophy, as the disease does not usually lead to deep erosions.
  • Rule out ulcers : If the fluorescein test is positive, this could indicate other causes such as corneal ulcers or injuries that require differential diagnosis.

Optical coherence tomography (OCT)

Optical coherence tomography is a modern imaging technique that shows the layers of the cornea in detail and is particularly helpful in diagnosing endothelial dystrophy.

  • Layer differentiation : With the help of OCT, different layers of the cornea can be displayed in detail and changes such as deposits or fluid accumulations can be localized.
  • Early detection : In genetically predisposed dogs, OCT can detect early signs of corneal dystrophy before symptoms become visible.

Corneal topography

Corneal topography is used in the diagnosis of corneal dystrophies to demonstrate structural and refractive changes in the corneal surface.

  • Topographic map : Topography creates a color map that shows the curvature and structure of the cornea and reveals irregularities in corneal thickness.
  • Differentiation from other diseases : Corneal topography can help differentiate dystrophies from other structural changes such as corneal scars or degenerative changes.

Electroretinography (ERG)

Electroretinography examines the function of the retina and is used for exclusion diagnosis to rule out retinal diseases as the cause of vision loss.

  • ERG results in corneal dystrophy : In dogs with corneal dystrophy, ERG results are typically normal because the retina is not affected. This helps rule out conditions such as progressive retinal atrophy (PRA).

Detailed medical history and genetic testing

A thorough medical history and genetic testing are helpful in identifying a genetic predisposition. This is particularly important in dog breeds that are more commonly affected by corneal dystrophy.

  • Anamnesis interview : This determines whether there are any genetic predispositions, e.g. B. whether the dog's relatives have similar eye diseases.
  • Genetic testing : DNA testing allows breeders or veterinarians to identify specific genetic markers that indicate a predisposition to corneal dystrophy, allowing for an accurate diagnosis.

2. Differential diagnosis: Differentiation from other diseases

The differential diagnosis of corneal dystrophy is crucial to rule out other diseases that cause similar symptoms. The most common differential diagnostic considerations include:

2.1 Corneal degeneration

Corneal degenerations are similar to corneal dystrophies, but are caused by different causes and are usually secondary to other diseases. They can also lead to clouding and deposits in the cornea.

  • Difference from corneal dystrophy : In contrast to corneal dystrophy, corneal degeneration is not genetic, but often occurs as a result of inflammation, trauma or systemic diseases (e.g. diabetes or thyroid problems).
  • Clinical differentiation : Corneal degenerations are usually unilateral and often show patchy deposits. A precise anamnesis and examination for systemic diseases help to distinguish it from corneal dystrophy.

2.2 Keratoconjunctivitis sicca (KCS)

Keratoconjunctivitis sicca, also known as “dry eye,” causes damage to the cornea due to inadequate tear production and leads to cloudiness and pigment deposits in the cornea.

  • Symptoms of KCS : In contrast to corneal dystrophy, KCS leads to typical symptoms such as viscous eye discharge, redness and often pain. The affected cornea often shows pigmentation that is absent in corneal dystrophy.
  • Schirmer tear test : A Schirmer test to measure tear production helps to identify KCS as a possible cause of corneal problems and to differentiate it from corneal dystrophy.

2.3 Corneal ulcers

Corneal ulcers are painful injuries to the cornea caused by infection, trauma, or systemic disease. They can also cause clouding and loss of vision.

  • Painful symptoms : Unlike corneal dystrophy, which usually does not cause pain, corneal ulcers are painful. Dogs with corneal ulcers often rub their eyes and show significant sensitivity to light.
  • Fluorescein test : A positive fluorescein test often shows corneal ulcers that are clearly defined in the damaged areas due to dye absorption. Corneal dystrophy, on the other hand, usually does not result in positive fluorescein staining.

2.4 Progressive retinal atrophy (PRA)

Progressive retinal atrophy is a genetic disease of the retina that, like corneal dystrophy, often occurs in certain breeds of dogs and also leads to blindness.

  • Different cause : Unlike corneal dystrophy, PRA affects the retina and not the cornea. Symptoms such as night blindness and progressive vision deterioration are more severe with PRA.
  • Electroretinography (ERG) : ERG can clearly diagnose retinal diseases such as PRA as it shows abnormal ERG results, while in corneal dystrophy the ERG values ​​are normal.

2.5 Glaucoma

Glaucoma is an eye disease characterized by increased intraocular pressure that can lead to optic nerve damage and blindness. Corneal clouding can also occur.

  • Typical symptoms : Dogs with glaucoma often show symptoms such as redness of the eye, dilation of the pupil, and pain. The cornea often appears bluish-gray due to increased intraocular pressure.
  • Measuring intraocular pressure (tonometry) : Measuring intraocular pressure is a key test for differentiating corneal dystrophy, as increased pressure is detected in glaucoma, while intraocular pressure remains normal in corneal dystrophy.

2.6 Lipid deposits caused by systemic diseases

Systemic diseases such as diabetes or hypothyroidism can also lead to lipid deposits in the cornea, causing a cloudy coloration similar to corneal dystrophy.

Treatment

Treating corneal dystrophy in dogs is a complex challenge due to its genetic basis and often progressive course. Because a cure is not possible, treatment approaches focus on managing symptoms, delaying disease progression, and improving quality of life. Treatment options vary depending on the form and stage of corneal dystrophy and include both conservative and surgical approaches. A comprehensive overview of the currently available treatment methods is provided below.

1. Conservative treatment

Conservative therapy aims to relieve symptoms and slow the progression of the disease. This is often the first choice, especially when corneal dystrophy is in its early stages or in older dogs who are not amenable to invasive procedures.

Eye drops and eye ointments

  • Moisturizing drops : Artificial tears or moisturizing drops are particularly useful in dogs with epithelial dystrophy to keep the corneal surface moist and relieve irritation. These preparations are used several times a day and help to strengthen the protective layer of the cornea and stabilize the tear film.
  • Hypertonic saline solutions : Hypertonic solutions such as 5% sodium chloride eye drops or ointments are prescribed specifically for endothelial dystrophy. These help remove excess fluid from the cornea, which reduces corneal edema and relieves clouding. However, these preparations are not a cure and often need to be used long-term.
  • Antioxidant eye drops : There are some antioxidant eye drops that are designed to protect the cells of the cornea. While these are controversial, some studies suggest that antioxidant supplements may reduce oxidative damage, particularly in genetically susceptible dogs.

Medical therapy

  • Anti-inflammatory medications : For dogs that develop eye irritation and mild inflammation due to corneal dystrophy, anti-inflammatory medications in the form of eye drops may help. These medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), have a calming effect on the cornea and relieve redness and irritation.
  • Antibiotic treatment : Antibiotic therapy is necessary for secondary bacterial infections that may arise due to microerosions in the cornea. Antibiotic eye drops or ointments are often used short-term to fight the infection and prevent complications.

2. Laser therapy and phototherapeutic keratectomy (PTK)

Phototherapeutic keratectomy is a minimally invasive laser therapy that can be used successfully in some cases of corneal dystrophy, particularly stromal plaques. An excimer laser is used to remove the top layer of the cornea, which can remove lipid deposits and reduce haze.

  • Aim of PTK : PTK aims to improve visual acuity and smooth the corneal surface. This is particularly helpful in stromal dystrophies, where crystals or lipid deposits impair vision.
  • Advantages : The procedure is relatively painless and has a short recovery time. PTK also offers the advantage that no larger surgical incisions are required.
  • Limitations : However, PTK is not suitable for endothelial dystrophy because this disease affects the deepest layer of the cornea, which cannot be reached with this method. There is also the possibility of a recurrence as the lipids can be deposited again.

3. Surgical treatment options

In advanced cases or in dogs that do not respond adequately to conservative forms of therapy, surgical intervention may be necessary. However, surgical procedures often involve higher risks and should only be considered after careful consideration and in stable dogs.

Corneal transplant (keratoplasty)

Corneal transplantation or keratoplasty is the only way to replace the damaged cornea with donor tissue. It is considered in dogs with advanced endothelial dystrophy.

  • Procedure of the operation : During keratoplasty, the affected layer of the cornea or, in severe cases, the entire cornea is removed and replaced with a transplant. This operation is technically demanding and requires special equipment and experience in the field of veterinary ophthalmology.
  • Risks and Challenges : Corneal transplantation carries several risks, including graft rejection, infection, and the need for long-term immunosuppressive therapy. Dogs undergoing this procedure require intensive follow-up care and regular check-ups.
  • Success Rate and Prognosis : Although keratoplasty can be successful in dogs with corneal dystrophy, the long-term prognosis is variable. The success rate is usually higher in young animals and those in stable general health.

Thermokeratoplasty

Thermokeratoplasty is an alternative method for treating endothelial dystrophy. This procedure uses controlled heat to thicken the cornea, improving transparency and reducing edema.

  • Indications : This procedure is particularly suitable for older dogs for whom traditional keratoplasty would be too risky or who cannot tolerate general anesthesia due to health restrictions.
  • Benefits : Thermokeratoplasty is less invasive than a full corneal transplant and requires a shorter healing time. The procedure is usually well tolerated and can be carried out on an outpatient basis.
  • Disadvantages : The success of thermokeratoplasty is usually temporary, as the corneal structure can accumulate fluid again over time. Therefore, the procedure may need to be repeated to achieve long-term relief.

4. Nutritional support and supplements

Although corneal dystrophy is a genetic disease, certain nutrients can support the health of the cornea and positively influence the progression of the disease. The following nutritional supplements and nutritional approaches have been shown to be helpful:

  • Omega-3 and Omega-6 fatty acids : These fatty acids have anti-inflammatory properties and can help improve the integrity of cell membranes. Omega-3 fatty acids from fish oil have an antioxidant effect and can support the health of the cornea.
  • Antioxidants : Antioxidant vitamins such as vitamin C and vitamin E, as well as minerals such as zinc and selenium, can help reduce oxidative stress in the cornea. This stress contributes to the degeneration of corneal structures, especially in genetically predisposed dogs.
  • L-Carnitine and Taurine : These amino acids are important for cell function and growth and may indirectly support corneal health.

5. Quality of life management and environmental adaptations

In addition to medical treatment, it is crucial to adapt the affected dog's daily life to provide him with the highest possible quality of life. Some management strategies are:

  • Light Adjustments : Because many dogs with corneal dystrophy are sensitive to light, direct sunlight in their environment should be reduced. Windows can be equipped with UV-repellent films and bright light sources in the house can be reduced.
  • Living space adjustment : Dogs with limited vision need an environment that is as consistent as possible and does not move furniture and other obstacles. This makes orientation easier and reduces the risk of the dog getting injured.
  • Use of aids : There are special goggles for dogs that protect the cornea from UV light while reducing mechanical irritation. These glasses are particularly suitable for dogs that enjoy being active outdoors and need an additional protective barrier.
  • Boost sensory perception : Dogs with vision problems rely more heavily on their other senses. Orientation can be improved by specifically promoting the sense of smell and hearing.

The treatment of corneal dystrophy in dogs is multifaceted and often requires a holistic approach that includes conservative forms of therapy, surgical options and supportive measures to improve quality of life. Because the disease is genetic, it cannot be completely cured but can be effectively managed through targeted therapies and environmental adjustments. Close monitoring and regular ophthalmological examinations are essential in order to detect the progression of the disease early and to create individual treatment plans that ensure the dog's long-term well-being.

Frequently asked questions about corneal dystrophy

What is corneal dystrophy and what are its causes?

Corneal dystrophy is a genetic disease of the cornea that causes cloudiness and deposits in the cornea. The disease usually progresses slowly and affects both eyes. The cause is hereditary defects in the cells of the cornea, which disrupt normal cell structure and function. Corneal dystrophy often occurs in certain breeds of dogs, such as Weimaraners, Collies and Huskies, which are genetically more susceptible.
Depending on which layer of the cornea is affected, a distinction is made between epithelial dystrophy (outer layer), stromal dystrophy (middle layer) and endothelial dystrophy (inner layer). This distinction is important because it affects the course and treatment of the disease. While epithelial dystrophy often results in small erosions, endothelial dystrophy can have a greater impact on vision due to fluid buildup.
The genetic component of corneal dystrophy means that the disease is not curable, but progression can be slowed through early diagnosis and targeted care approaches. Genetic testing of breeding dogs can identify certain risk factors, which is particularly important for breeds with increased susceptibility. Preventative measures in breeding can help reduce the prevalence of the disease in the long term.

What treatment options are available for corneal dystrophy and how effective are they?

Because corneal dystrophy is genetic, there is currently no cure. Treatment therefore focuses on managing symptoms to slow the progression of the disease and improve the affected dog's quality of life. The effectiveness of treatments depends largely on the form and progression of the disease.
Drug treatment : Moisturizing eye drops or ointments are used to protect the corneal surface and relieve irritation. Hypertonic solutions (e.g., 5% sodium chloride solution) help with endothelial dystrophy by removing fluid from the cornea and reducing corneal edema. In addition, anti-inflammatory or antibiotic drops can be used to treat accompanying inflammation or infections.
Laser treatment (Phototherapeutic Keratectomy) : This method is used to remove superficial deposits in stromal dystrophy and reduce opacity. PTK uses an excimer laser to specifically remove affected cells. However, this treatment is only suitable for certain forms of corneal dystrophy and cannot be used for endothelial dystrophy.
Surgical procedures : Corneal transplantation may be considered for advanced endothelial dystrophy. The damaged cornea is replaced with a donor transplant. However, this method is risky and requires intensive follow-up treatment as there is a risk of rejection.
Diet and Supportive Care : Antioxidants and omega-3 fatty acids can support corneal health. Light adjustments and avoiding strong sunlight can also help relieve symptoms.
The effectiveness of treatment varies for each form, and multiple approaches are often required to relieve symptoms and slow progression.

How is corneal dystrophy diagnosed and what further tests are necessary?

Diagnosing corneal dystrophy requires a combination of visual examination, imaging tests, and specialized tests that accurately analyze the condition of the cornea. The veterinary ophthalmologist usually begins with a thorough clinical examination of the eyes:
Visual inspection and slit lamp examination : The first step involves examining the cornea with a slit lamp to determine the degree of opacity and determine which layer is affected. In corneal dystrophy, the opacities often appear as milky-white spots in both eyes and are symmetrical.
Fluorescein test : To rule out superficial injuries, a fluorescein test is performed. This test shows whether the corneal surface is intact or has microdamage. Corneal dystrophies usually do not show fluorescein staining, which distinguishes them from corneal ulcers.
Optical coherence tomography (OCT) : OCT provides detailed images of the layers of the cornea and shows deposits or fluid collections. This method is particularly useful for endothelial dystrophy because it allows precise analysis of the inner layer of the cornea.
Genetic testing : For dog breeds that are genetically susceptible, genetic testing can help identify a predisposition. These tests are particularly important for breeding and risk assessment.
Differential diagnosis is also crucial to rule out other diseases such as corneal degeneration, progressive retinal atrophy, or glaucoma. A comprehensive diagnosis ensures that the correct treatment can be initiated and that the progression of the disease is controlled as best as possible.

What differential diagnoses need to be considered for corneal dystrophy?

In dogs with corneal clouding and vision loss, several differential diagnoses must be evaluated because various eye diseases can cause similar symptoms:
Corneal degeneration : Unlike corneal dystrophy, corneal degeneration is often a result of inflammation or systemic diseases such as diabetes. The opacities are often one-sided and patchy. A thorough examination of the medical history and the exclusion of underlying diseases help to differentiate.
Keratoconjunctivitis sicca (dry eye) : KCS leads to pigment deposits and clouding in the cornea due to inadequate tear production. Typical accompanying symptoms are thick eye discharge and redness. A Schirmer tear test can confirm whether there is a lack of tear fluid.
Corneal ulcers : Ulcers are painful and can result from infection or injury. A positive fluorescein test clearly shows the damaged areas of the cornea. Corneal dystrophy, on the other hand, usually causes no pain and no positive fluorescein staining.
Glaucoma : In glaucoma, the pressure within the eye is increased, which leads to a bluish-gray clouding of the cornea. Tonometry to measure intraocular pressure is necessary to rule out glaucoma, as corneal dystrophy is usually associated with normal eye pressure.
Progressive retinal atrophy (PRA) : PRA is a retinal disease that can also cause blindness. However, it affects the retina and not the cornea. Electroretinography (ERG) can help diagnose PRA because it shows abnormal results in this disease, while ERG remains normal in corneal dystrophy.
These differential diagnoses ensure that a clear distinction is made between corneal dystrophy, which is essential in order to choose the right therapy.

Can corneal dystrophy be prevented and what role does breeding play?

Because corneal dystrophy is a genetic disease, preventive measures are limited. The most important preventive strategy is breeding control for predisposed dog breeds. Breeders should have potential breeding animals tested for genetic markers to minimize the risk of inheriting corneal dystrophy.
Genetic tests : These tests identify specific genes or mutations that promote the disease. For breeds with high susceptibility - such as Weimaraners, Collies and Siberian Huskies - it is recommended to favor genetically tested animals in breeding to reduce the risk for future generations.
Elimination of affected dogs from breeding : Dogs suffering from corneal dystrophy should not be used for breeding to prevent genetic transmission. Animals that have been identified as having a genetic predisposition should also not be used as breeding animals.

Summary

Corneal dystrophy in older dogs is a genetic eye disease that often presents with clouding and loss of vision. Corneal dystrophy in older dogs can affect different layers of the cornea, causing varying symptoms such as sensitivity to light, eye irritation, or complete blindness depending on the area affected. often occurs in older dogs in breeds with a genetic predisposition, such as Weimaraners, Collies and Huskies, making these dogs particularly vulnerable as they age.

The diagnosis of corneal dystrophy in older dogs is usually made through a combination of clinical examination, slit lamp examination, and imaging techniques such as optical coherence tomography to accurately analyze the affected corneal layers. Treatment of corneal dystrophy in older dogs includes drug therapies, hydrating drops, and in advanced cases, surgery to slow progression and improve quality of life. Since a genetic cure for corneal dystrophy is not possible in older dogs , the focus is on symptomatic therapy.

Genetic testing to detect susceptibility to corneal dystrophy in older dogs can help reduce the disease through targeted breeding strategies. Preventing corneal dystrophy in older dogs can reduce the risk in future generations. Environmental factors such as care and nutrition can also have a positive influence on the course and reduce the severity and speed of corneal dystrophy in older dogs

Further information: https://www.cliniciansbrief.com/column/category/column/capsules/corneal-diseases-aging-dogs

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