Microphthalmia in Dogs: Causes, Signs & Breeding Advice

Microphthalmia is an inherited eye disorder in dogs where one or both eyes are abnormally small or underdeveloped. This congenital condition results from issues during fetal development. Although relatively rare, certain breeds such as Rottweilers are predisposed to microphthalmia. Other breeds at risk include Australian Shepherds, Shetland Sheepdogs, Corgis, Collies, Great Danes, Chihuahuas, Cocker Spaniels, and Pomeranians.

The condition explained

During a puppy's development in the womb, the eyes form over several weeks. Genetic abnormalities or structural defects may interfere, resulting in microphthalmia. This can affect one eye or both, causing the eyes to appear shrunken or recessed into the skull. In severe cases, eyes may be missing entirely or present with additional abnormalities such as a protruding third eyelid. Puppies born with microphthalmia may have varying degrees of impaired vision depending on the severity.

Breeds and dogs most at risk

Microphthalmia is more common in specific breeds and coat colours, particularly dogs with a merle or dapple coat exhibiting large white areas. The breeds known to be predisposed include Australian Shepherds, Shetland Sheepdogs, Corgis, Collies, Great Danes, Chihuahuas, Cocker Spaniels, and Pomeranians, alongside Rottweilers.

Signs of there being a problem

Signs that a dog may have microphthalmia include:

• One or both eyes appear unusually small or recessed, giving a sunken appearance
• The presence of a prominent third eyelid (nictitating membrane)

Diagnosing the problem

A thorough veterinary examination is essential for diagnosis. The vet will consider the dog's medical history and may recommend assessment by a veterinary ophthalmologist. Diagnostic tests could include:

• Blood tests to rule out infectious causes
• Imaging such as CT or MRI scans to view the eye and surrounding structures
• Cerebrospinal fluid analysis if neurological involvement is suspected

Treatment options

There is no cure for microphthalmia as it is a structural abnormality present from birth. However, many affected dogs can live full, active lives, especially if only one eye is affected and vision is partially retained. Management focuses on monitoring eye health and providing a safe environment for dogs with impaired sight. Surgical options might be considered for complications like cataracts if they occur alongside microphthalmia.

Breeding advice

Responsible breeding practices are crucial to prevent passing microphthalmia to future generations. Any dog diagnosed with microphthalmia, regardless of severity or whether one or both eyes are affected, should be neutered or spayed to avoid breeding. Additionally, breeders should avoid using lines known to carry the condition, thus reducing the risk of inherited defects in puppies.

What is microphthalmia in dogs?

Quick Answer: Microphthalmia is a congenital condition where a dog’s eyes are abnormally small or underdeveloped, affecting vision and eye appearance.

This disorder is caused by genetic and developmental factors during gestation, leading to visual impairment that can range from mild to severe. Often linked with specific breeds, it requires veterinary diagnosis to assess its extent and any associated defects.

Why are some dog breeds prone to microphthalmia?

Quick Answer: Some breeds inherit microphthalmia due to genetic factors, especially those with merle coat patterns linked to ocular abnormalities.

Breeds with particular coat colours, such as merle or dapple with extensive white areas, are genetically predisposed because the genes controlling pigmentation also influence eye development. This makes careful breeding, genetic testing, and screening essential to reduce prevalence in these lines.

Can microphthalmia be cured in dogs?

Quick Answer: No, microphthalmia cannot be cured as it is a structural defect; treatment focuses on managing symptoms and ensuring a good quality of life.

Since microphthalmia arises from underdeveloped eye structures formed during fetal growth, there is no established cure. However, dogs with this condition can often adapt well, especially if vision in one eye remains functional. Veterinary care focuses on monitoring eye health and managing secondary problems if they arise.