Category: Dermatologic (Associated with Skin).
Gene and Variant Detected: varies based on breed.
Severity: Mmoderate degree of severity, as it is not a fatal disease, though it can decrease the quality of life.
Breeds affected: Golden Retriever, Norfolk Terrier, American Bulldog.
Mode of Inheritance: Autosomal Recessive
Test Overview: A group of a hereditary, monogenic, cornification disorders, appearing early and persisting for life. Ichthyosis is characterized by abnormal desquamation over the whole body, where the skin becomes thickened and covered in scale.
The ichthyoses, are distinguishable clinically by generalized scaling and histopathologically, in most cases, by a thickened stratum corneum. In veterinary medicine, ichthyosis is now commonly classified into either epidermolytic or non-epidermolytic subtypes. Most reported cases in dogs are non-epidermolytic with heterogeneous clinical, histopathological and ultrastructural profiles.
The genetic mutation responsible for the disease has been characterized in several breeds. It is thought that the defect relates to the metabolism of lipids within the epidermis (outer layer of the skin).
Signs associated with ichthyosis can start from a very young age in some breeds, with hairless skin on the underside becoming reddened and then developing a brown scale and a wrinkly appearance. By the time the dog reaches adulthood the underside of the dog is covered in brown scale, with white-to-tan scales visible in haired areas. The feet may occasionally be affected with thickening and cracking of the footpads. The main complication from this condition is that the skin’s defensive barrier function is impaired, and cracking allows organisms to penetrate the skin, leading to infections. Yeast overgrowth is the most common complication, leading to severe itching and irritation and also conditions such as otitis externa, intertrigo (infection in the skin folds) and pododermatitis (infection of the feet). The condition can also be quite distressing for the owner due to the appearance of their dog and the irritation caused, although the disease itself is not directly life-threatening.
The most common form of ichthyosis seen in veterinary practice is the tardive ichthyosis seen in golden retrievers and their crosses. This type is generally seen in young adulthood, typically starting around one year of age, and presents as scaling and white flaky dandruff, sometimes with ventral hyperpigmentation. This is also the form of ichthyosis most amenable to treatment, often with appropriate topical therapy and nutritional supplementation.
Several forms of ichthyosis in dogs, but not all, are now detectable through genetic screening.