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Microphthalmia (Small Eyeballs) in Dogs

Author: Dr. med. vet. Gisa Löwe | Last modified: 17.02.2026

When to visit the vet?

Home care monitor at home and contact your vet if worse

YELLOW/ORANGE if not congenital/new onset, with Pain/inflammation or vision problems; then clarify differentials (e.g., phthisis bulbi).

Unsure about what’s wrong with your pet? Feel free to use our Symptom Checker for more clarity

Definition

Microphthalmia is a developmental anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later. in which a dog’s eyeballs are smaller than normal. This malformation can occur on one side or both sides and often affects the affected animal’s vision.

Can Occur with the Following Diseases:

Collie Eye Anomaly, CEA

Basics and possible causes

Microphthalmia is a 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. anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later., meaning it is already present at birth. It can have genetic causes and sometimes occurs as an inherited condition, especially in certain dog breeds. Breeds in which microphthalmia is more commonly observed include the Collie and the Australian Shepherd, among others.

From a scientific perspective, microphthalmia results from a disruption in the embryonic development of the eyes. During embryogenesis, as the eye develops, genetic mutations or environmental factors such as infections, medications, or nutrient deficiencies can impair normal eye development.

Genetic factors play a significant role, and in some cases microphthalmia can be part of a broader syndromeA syndrome is a group of symptoms that occur together and indicate a specific disease or condition. A syndrome can be caused by various factors and is often complex in its diagnosis and treatment. that includes multipleMultiple means manifold or repeated and is used to describe conditions or events that occur in multiple instances or at different locations. In veterinary medicine, this may indicate multiple lesions, tumors, or other pathological changes. physical anomalies. Mutations in certain genes responsible for eye development can lead to this anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later.. Environmental factors during pregnancy, such as viralViral refers to viruses and their effects on the organism. Viral infections in dogs and cats can range from harmless colds to severe, life-threatening diseases. illness or toxinA toxin is a poison produced by living cells or organisms that can be harmful to the body upon contact or ingestion. Toxins can originate from bacteria, plants, animals, or fungi. exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats., can also contribute to the development of microphthalmia.

Typical accompanying symptoms

Reduced vision: Dogs with microphthalmia often have limited or no vision, especially if both eyes are affected.
Irregular eye movements: The eyes may move uncontrollably or in irregular patterns, which may indicate neurological involvement.
Unusual eye shape or size: The affected eyes appear smaller and may be irregularly shaped, which also affects the dog’s external appearance.
Other eye anomalies: Associated anomalies such as cataracts, colobomas (clefts in the irisThe iris is the colored part of the eye that surrounds the pupil. It consists of muscle tissue and adjusts the size of the pupil through its contraction or relaxation to regulate the amount of light that enters the eye., retinaThe retina is the light-sensitive layer at the back of the eye that captures visual information and transmits it to the brain via the optic nerve. Retinal diseases can lead to vision loss in dogs and cats., or optic nerveThe optic nerve is the nerve that connects the retina of the eye to the brain and transmits visual information. Diseases or damage to the optic nerve in dogs and cats can lead to vision loss or blindness.), or an underdeveloped irisThe iris is the colored part of the eye that surrounds the pupil. It consists of muscle tissue and adjusts the size of the pupil through its contraction or relaxation to regulate the amount of light that enters the eye. may occur.
Inflammatory conditions or infections: Due to the structural anomalies, the eyes may be more susceptible to infections or Inflammatory conditions.

When to see a vet?

If you notice signs of microphthalmia in your dog, you should consult a veterinarian as soon as possible. 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. is important to prevent possible complications and improve the dog’s quality of life.

A veterinary visit is especially important if your dog has trouble finding its way around, bumps into objects, or shows signs of Pain or discomfort. Even if the eye looks inflamed or has discharge, a veterinary examination is necessary to rule out infections.

Symptom recognition for the pet owner and veterinary diagnostic procedure

Detecting microphthalmia as a pet owner can be challenging, especially if only one eye is affected or the anomalies are subtle. Watch for unusual behavior in your dog, such as difficulty seeing or Disorientation in unfamiliar environments.

The veterinarian will perform a thorough eye exam, including an inspection of the external eye structure as well as an assessment of the internal parts of the eye. This may include using special instruments such as an ophthalmoscope to examine the retinaThe retina is the light-sensitive layer at the back of the eye that captures visual information and transmits it to the brain via the optic nerve. Retinal diseases can lead to vision loss in dogs and cats. and optic nerveThe optic nerve is the nerve that connects the retina of the eye to the brain and transmits visual information. Diseases or damage to the optic nerve in dogs and cats can lead to vision loss or blindness..

In addition, imaging procedures such as ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. or skull X-rays can be used to assess eye structure and possible associated malformations. If a genetic cause is suspected, genetic counseling or testing may be considered.

What the pet owner can do and professional therapy options

As a pet owner, you should first make sure your dog lives in a safe environment, especially if vision is significantly impaired. Remove potentially dangerous objects the dog could injure itself on, and avoid environments that are challenging or dangerous for the dog.

A balanced diet rich in nutrients essential for eye health, such as omega-3 fatty acids, can be supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease.. Talk to your veterinarian about special diets or supplements that might help promote eye health.

Regular veterinary check-ups are crucial to monitor the condition of the eyes and detect complications early. If there are signs of Pain or 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., consult your veterinarian immediately to receive appropriate treatments such as antibiotics or anti-inflammatory medications.

Although microphthalmia itself is not curable, many of the accompanying symptoms and complications can be effectively managed with proper care and regular veterinary care to ensure your dog’s quality of life.

Outlook on current research

Current research on microphthalmia in dogs focuses on the genetic and environmental factors that lead to the development of this anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later.. Researchers often investigate the 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. of certain dog breeds, since some breeds tend to develop microphthalmia more frequently. Genetic markers and mutations linked to the development of this symptom are the subject of intensive study. By identifying specific genetic factors, scientists hope to better guide breeding programs and reduce the occurrence of this anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later. in future generations.

Another research focus is studying embryonic eye development to understand the mechanisms that lead to incomplete development of the eyeballs. Using animal models and cellularCellular refers to cells or consisting of cells. In biology and medicine, it refers to processes, structures, or functions that occur at the level of individual cells. assays, scientists try to identify the critical developmental phases in which malformations occur. In the long term, this research could contribute to developing therapeutic approaches to reduce or prevent the effects of microphthalmia.

In addition, environmental factors that may contribute to microphthalmia are being studied. These include infections during pregnancy, malnutrition, and exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats. to toxicToxic means "poisonous" and refers to substances that can have harmful effects on the body, including damage to organs, cells, or disruption of metabolic processes. substances. These studies are crucial for developing preventive measures that can reduce the risk of microphthalmia in newborn puppies.

An emerging research direction looks at the impact of microphthalmia on the quality of life of affected dogs. Through behavioral studies and neurological examinations, researchers aim to understand how visual impairment affects cognitiveCognitive refers to the mental processes of recognizing, thinking, learning, and understanding. Cognitive functions in dogs and cats include memory, perception, problem-solving, and decision-making. Cognitive dysfunction can occur in older animals and is similar to dementia in humans. abilities and overall well-being. This research could provide the basis for developing supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. measures and aids that improve the lives of dogs with microphthalmia.

Some studies also address surgical correction of microphthalmia, especially in cases where the anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later. is associated with other structural eye problems. The effectiveness and safety of such procedures are being investigated to determine whether surgical interventions are a viable option for affected animals. The results of these studies could help develop new treatment strategies and improve the quality of life of affected dogs.

The role of modern imaging techniques, such as high-resolution ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. and magnetic resonance imaging (MRI)Magnetic resonance imaging is an imaging technique that uses strong magnetic fields and radio waves to create detailed images of the inside of the body. It is used in veterinary medicine to diagnose diseases of the brain, spine, and other organs., is also being studied to enable early and accurate 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 microphthalmia. By using these technologies, researchers hope to detect subtle structural anomalies that might be missed with traditional diagnostic methods. These advances could increase diagnostic accuracy and allow more targeted treatment.

Collaboration between geneticists, veterinarians, and ophthalmologists is an essential part of microphthalmia research. Interdisciplinary approaches make it possible to develop a more comprehensive understanding of the anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later. and find innovative solutions. In the long term, this collaboration could lead to a reduction in the prevalence of microphthalmia and improvement in the quality of life of affected dogs.

One challenge in research is the variability of the symptom in different dogs, which makes it difficult to identify general mechanisms. Differences in the severity of microphthalmia, even within the same breed, require tailored research approaches to identify underlying causes and potential treatment strategies. This complexity is a significant challenge, but it also offers the opportunity to gain deeper insight into the genetic and biological mechanisms of eye development.

Advances in gene-editing technology, such as CRISPR, offer potential new opportunities to study and treat microphthalmia. By specifically manipulating genes associated with eye development, researchers can directly investigate the effects of particular genetic changes on the development of microphthalmia. In the future, this technology may also find therapeutic applications to correct genetic defects and promote normal eye development.

Research into microphthalmia in dogs is a rapidly developing field with many challenges and opportunities. By combining genetic, environmental, and developmental biology approaches, scientists hope to gain a comprehensive understanding of this anomalyAn anomaly is a deviation from what is considered normal or expected. In medicine, it often refers to unusual physical or genetic characteristics that may be present at birth or develop later. and develop innovative solutions that can improve the lives of dogs with microphthalmia.

Frequently asked questions

1. What is microphthalmia in dogs?

Microphthalmia in dogs is a developmental anomaly in which the eyeballs are smaller than normal. This anomaly can occur on one side or both sides and can lead to varying degrees of visual impairment.

2. Which breeds are most commonly affected?

Certain dog breeds such as the Collie, Australian Shepherd, and Chihuahua are more commonly affected by microphthalmia. This is often due to genetic predisposition that is common within the breeds.

3. How is microphthalmia diagnosed?

Microphthalmia is usually diagnosed through a thorough clinical examination of the eyes by a veterinarian. Imaging procedures such as ultrasound or MRI can be used to confirm the diagnosis.

4. Can microphthalmia be treated?

There is no cure for microphthalmia, but the symptoms can be treated. In some cases, surgery can help correct structural problems and improve the dog’s quality of life.

5. What effect does microphthalmia have on vision?

The impact on vision can vary from mild visual impairment to complete Blindness, depending on the severity of the anomaly and whether both eyes are affected.

6. Are there preventive measures against microphthalmia?

Preventive measures include carefully selecting breeding animals to minimize genetic predisposition, as well as avoiding environmental factors that can increase risk during pregnancy.

7. Can microphthalmia occur with other anomalies?

Yes, microphthalmia can occur together with other genetic or structural anomalies, such as cataracts or colobomas, making a comprehensive examination and diagnosis necessary.

8. How does microphthalmia affect the behavior of dogs?

Dogs with microphthalmia may show behavioral adjustment difficulties, especially in unfamiliar environments. They may be more cautious or anxious, which can be reduced through targeted training and support.

9. Is microphthalmia in dogs hereditary?

Yes, microphthalmia can be inherited, especially when it is due to genetic mutations that are common in certain breeds. Genetic counseling can help minimize the risk in future generations.

10. What research is being done on microphthalmia in dogs?

Research includes genetic studies, investigations of embryonic eye development, studies on environmental factors, and the development of therapeutic approaches to improve the lives of dogs with microphthalmia.