Vogt–Koyanagi–Harada syndrome (VKH syndrome) is a condition seen in humans and dog

Dog

The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

s involving various melanocyte-containing organs, characterized by uveitis

Uveitis

Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....

 (inflammation of the inside of the eye

Human eye

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

), poliosis

Poliosis

Poliosis is the decrease or absence of melanin in head hair, eyebrows, or eyelashes. It can give rise to a "Mallen Streak" that can be hereditary....

 (whitening of hair), vitiligo

Vitiligo

Vitiligo is a condition that causes depigmentation of sections of skin. It occurs when melanocytes, the cells responsible for skin pigmentation, die or are unable to function. The cause of vitiligo is unknown, but research suggests that it may arise from autoimmune, genetic, oxidative stress,...

 (loss of pigment

Pigment

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...

 in the skin), and meningitis

Meningitis

Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...

, although dogs with this syndrome rarely develop meningitis. It is also known as uveodermatologic syndrome.

Pathophysiology

VKH syndrome is an immune-mediated disease. The mechanism of the disease is thought to be T helper cell

T helper cell

T helper cells are a sub-group of lymphocytes, a type of white blood cell, that play an important role in the immune system, particularly in the adaptive immune system. These cells have no cytotoxic or phagocytic activity; they cannot kill infected host cells or pathogens. Rather, they help other...

 mediated autoimmune attack of melanocyte

Melanocyte

-External links: - "Eye: fovea, RPE" - "Integument: pigmented skin"...

s in the skin and uvea

Uvea

The uvea , also called the uveal layer, uveal coat, uveal tract, or vascular tunic, is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when...

 of dogs and humans, and in the central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

 and inner ear

Inner ear

The inner ear is the innermost part of the vertebrate ear. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:...

 of humans.

In humans there is a higher rate of VKH syndrome in people of Asian, Latin, and Mediterranean descent.

VKH syndrome in dogs

In dogs VKH syndrome (often called VKH-like syndrome) most commonly affects young animals and is seen most commonly in the Akita Inu, but also in the Siberian Husky

Siberian Husky

The Siberian Husky is a medium-size, dense-coat working dog breed that originated in north-eastern Siberia. The breed belongs to the Spitz genetic family...

 and Samoyed

Samoyed (dog)

The Samoyed dog takes its name from the Samoyedic peoples of Siberia. An alternate name for the breed, especially in Europe, is Bjelkier...

. Uveitis usually occurs first and is often severe enough to cause blindness. VKH syndrome can also cause retinal detachment

Retinal detachment

Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.The retina is a...

, cataract

Cataract

A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...

s, and glaucoma

Glaucoma

Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...

. Pigment partly disappears from the retinal pigment epithelium and iris

Iris (anatomy)

The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...

. Skin lesions include loss of pigment and hair on the eyelids, nose, and lips. Symptoms and biopsy

Biopsy

A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 will confirm the diagnosis. Treatment is with immunosuppressive drug

Immunosuppressive drug

Immunosuppressive drugs or immunosuppressive agents are drugs that inhibit or prevent activity of the immune system. They are used in immunosuppressive therapy to:...

s such as prednisone

Prednisone

Prednisone is a synthetic corticosteroid drug that is particularly effective as an immunosuppressant drug. It is used to treat certain inflammatory diseases and some types of cancer, but has significant adverse effects...

 and azathioprine

Azathioprine

Azathioprine is a purine analogue immunosuppressive drug. It is used to prevent organ rejection following organ transplantation and to treat a vast array of autoimmune diseases, including rheumatoid arthritis, pemphigus, inflammatory bowel disease , multiple sclerosis, autoimmune hepatitis, atopic...

. The prognosis

Prognosis

Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...

is guarded.