Congenital Keratoconjunctivitis Sicca, KCS (Dry Eye) in Dogs
- Occurrence: very rare
- Location of disease: Head/Neck
When to visit the vet?
Non-urgent see a veterinarian within 2–3 days
If the condition worsens / symptoms persist, consult a veterinarian.
Definition
CongenitalCongenital means "present from birth" and refers to characteristics or conditions that are already present at birth. This can include genetic disorders, developmental anomalies, or infections transmitted by the mother. keratoconjunctivitis sicca (KCS), also known as “Dry eye”, is a condition in dogs characterized by insufficient tear production, leading to dry, inflamed, and irritated eyes.
The most important facts at a glance
Congenital keratoconjunctivitis sicca is a genetically determined tear gland dysfunctionDysfunction refers to an impaired or abnormal function of an organ or system in the body. This can be due to diseases, disorders, or damage and can affect the quality of life. in dogs that leads to dry, inflamed eyes as early as puppyhood and, if left untreated, to blindness. DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made by Schirmer test; therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. requires lifelong topicalTopical refers to the direct application of medications or treatments to the skin or mucous membranes for a local effect, without being absorbed into the body. treatment with tear substitutes and anti-inflammatory preparations. With consistent care, good quality of life is achievable, but the condition is not curable.
Causes
A dog’s eye is protected by a tear film consisting of three layers: an outer lipid layer, a middle aqueous layer, and an inner mucin layer. These layers are essential for eye health, as they lubricate the eye surface, protect against infections, and flush out foreign bodies. In KCS, the production of the aqueous layer is impaired, leading to drying of the eye surface.
The causes of KCS are varied. One of the most common causes is an autoimmune disease in which the dog’s immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. attacks and destroys the tear glands. This form of KCS frequently occurs in certain breeds such as Cocker Spaniels, West Highland White Terriers, and Bulldogs. Genetic factors also play a role, which is why KCS is often referred to as “congenitalCongenital means "present from birth" and refers to characteristics or conditions that are already present at birth. This can include genetic disorders, developmental anomalies, or infections transmitted by the mother..”
Other causes of KCS can include certain medications that inhibit tear production, such as some types of antihistaminesAntihistamines are medications that block the effects of histamine in the body, thereby alleviating allergic reactions. They are used in dogs and cats to treat Itching, Skin inflammation, and other allergy symptoms. or sulfonamides. Systemic diseases such as diabetes or hypothyroidism can also impair tear production. In rare cases, traumaA trauma refers to a physical injury or damage caused by external force. Traumas can range from simple cuts to severe multiple injuries. or surgical removal of the third eyelid gland can also lead to KCS.
Environmental factors such as dry air or chemical irritants can worsen the symptoms of KCS but are rarely the primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. cause of the condition.
Symptoms
The symptoms of KCS in dogs are often easy to recognize, as they are usually associated with visible changes to the eye. Affected dogs frequently show redness of the conjunctiva (conjunctivitis), caused by chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. dryness and irritation of the eyes.
Another common symptom is a thick, yellowish discharge from the eyes, which may indicate a bacterial infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. promoted by reduced tear production. The eyelids may appear stuck together, and the dog may have difficulty opening the eyes fully.
Dogs with KCS blink frequently, rub their eyes with their paws or on the ground, and may show signs of pain or discomfort. In advanced cases, corneal ulcerations can occur, which if left untreated can lead to blindness.
Another sign may be thickening and pigmentation of the cornea, which is called keratitis. This thickening leads to clouding of the eye and can impair the dog’s vision.
The key sign is the combination of “chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. redness of the conjunctiva + thick eye discharge + dry, dull cornea” at a young age.
Diagnosis
The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. of KCS is usually made through a combination of clinical examination and special tests. A Schirmer tear test is the most common test to measure tear production. A special strip of blotting paper is placed in the lower conjunctival sac to measure the amount of tears produced within one minute.
In addition to measuring tear production, the veterinarian performs a thorough ophthalmologic examination to rule out other conditions that could cause similar symptoms, such as conjunctivitis or corneal injuries.
A fluorescein stain can be performed to identify possible damage or ulcers on the cornea. This stain shows areas where the cornea is damaged, as the dye can penetrate these small defects.
In some cases, a blood testA blood test is a laboratory procedure in which blood is drawn and analyzed to obtain information about the body's health. It can include various parameters such as blood sugar, blood count, liver and kidney values. may be helpful to rule out systemic diseases that could cause or worsen KCS.
Therapy
The treatment of KCS aims to increase tear production, relieve symptoms, and prevent complications. One of the main treatments is the application of eye drops or ointments that either contain artificial tears or promote the production of natural tears.
Cyclosporine eye ointments are frequently prescribed as they can suppress the immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. and improve tear gland function. Another option is medications that directly stimulate tear production, such as pilocarpine.
Artificial tear substitutes are frequently used to relieve symptoms and protect the cornea. These often need to be applied several times daily, especially in dry climates or in more severe cases of KCS.
In severe cases where medication is insufficient, surgical intervention such as parotid duct transposition may be considered. This involves redirecting the salivary duct so that it delivers tears to the eye surface.
Antibiotic eye drops or ointments may be necessary to treat secondary bacterial infections that can occur due to reduced tear production.
Prognosis and follow-up care
The prognosis for dogs with KCS depends on the severity of the condition and the response to treatment. In many cases, the condition can be well controlled with consistent treatment, and the dog can lead a relatively normal life.
Early diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment are crucial to prevent permanent corneal damage and possible blindness. With early treatment, many dogs respond well to therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. and show significant improvement in symptoms.
In severe or chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. cases, however, the condition may progress, and the dog may suffer permanent vision impairment. Regular veterinary checkups are important to monitor the condition and adjust treatment plans as needed.
The quality of life of dogs with KCS can be significantly improved through regular care and adherence to treatment plans.
Prevention
Since KCS is often genetically determined, there is no absolute preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring., but some measures can reduce the risk or slow the progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. of the disease. Selecting breeding animals without a family historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits. can help minimize occurrence in offspring.
Regular eye examinations by a veterinarian can help detect the condition early, before irreversible damage occurs. Especially in breeds susceptible to KCS, these examinations should be part of routine health care.
Avoiding medications known to inhibit tear production can also be helpful. If such medications are necessary, the veterinarian should be informed about alternative treatment options.
A healthy lifestyle, including a balanced diet and avoiding environmental factors that can cause eye irritation, contributes to overall eye health and can reduce the risk of KCS.
Outlook on current research
Research on congenitalCongenital means "present from birth" and refers to characteristics or conditions that are already present at birth. This can include genetic disorders, developmental anomalies, or infections transmitted by the mother. keratoconjunctivitis sicca (KCS), also known as “dry eye,” in dogs has made significant progress in recent years. Scientists are focusing on better understanding the genetic and environmental factors that contribute to the development of this condition. Some studies suggest that certain dog breeds have a genetic predispositionA predisposition is an innate inclination or susceptibility of an organism to certain diseases or conditions. In dogs and cats, there may be a genetic predisposition to certain conditions such as hip dysplasia or certain heart diseases. for KCS, indicating specific genetic markers that may increase the risk of developing this condition. These findings could lead to improved breeding programs in the future that reduce the risk of KCS.
Another important area of research is the development of new and improved treatment methods. Novel medications and therapeutic approaches are currently being investigated to more effectively relieve the symptoms of KCS and improve the quality of life of affected dogs. These include the use of growth factors to stimulate tear production as well as the application of stem cell therapies that have the potential to regenerate damaged tear glands and restore natural tear production.
The role of environmental factors and their influence on the development and progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. of KCS is also being intensively researched. This includes studies on how air pollution, climatic conditions, and even diet can affect the eye health of dogs. This research could lead to preventive measures that reduce the risk of KCS occurrence.
Long-term studies on the efficacy and safety of new treatment approaches are ongoing, and initialInitial means beginning or at the start. In medicine, it can refer to the first symptoms of a disease or the first phase of a treatment process. results are promising. The use of personalized therapies based on a dog’s specific genetic and physiological characteristics is seen as a potential breakthrough in the treatment of KCS. These individualized approaches could improve treatment effectiveness and minimize side effects.
In summary, research on congenitalCongenital means "present from birth" and refers to characteristics or conditions that are already present at birth. This can include genetic disorders, developmental anomalies, or infections transmitted by the mother. keratoconjunctivitis sicca in dogs has entered an exciting phase. New scientific findings and technological advances offer hope that more effective preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. and treatment strategies can be developed soon to improve the well-being and eye health of dogs worldwide.