Congenital and Inherited Skin Disorders in Dogs

Epitheliogenesis imperfecta, also called aplasia cutis, might be conventionally described as missing or absent skin. It is a congenital condition of unknown cause that is most frequently seen in cattle, pigs, sheep, and horses. It is a rare condition in cats and dogs. Animals with epitheliogenesis imperfecta have failed to develop part or all of the layers of the skin. As a result, the animal is born with ulcers or with areas that lack any skin covering. Missing claws and other abnormalities may also be present. The condition can be fatal if it involves large portions of the skin. Small defects can be surgically corrected.

A nevus in humans is a congenital pigmented area on the skin that is often called a birthmark. In animals, the term is used for any area where skin is malformed, including abnormally pigmented spots. Some forms of nevi displace the normal structures of the skin, including hair follicles; thus, these patches are hairless. When not extensive, nevi can be surgically removed or treated with laser treatment or cryotherapy (freezing); otherwise no effective treatment is available.

Dermoid cysts are birth defects that may occur in Rhodesian Ridgebacks (in which they are inherited) and occasionally other breeds of dogs. These are skin pockets into which dander, hair, oil, and other debris accumulate. They are found on skin above the backbone but are rarely associated with spinal cord neural deficits. They can be surgically removed. Follicular cystsoccur when hair follicles do not form correctly and fill with secretions.

Dogs can be born either totally or partially without hair. Hairlessness (alopecia) can also develop later in life. These defects can be associated with abnormal teeth, claws, and eyes, or with skeletal and other developmental defects. Hairless breeds of dogs (Mexican Hairless, Chinese Crested, American Hairless Terrier) have been bred for these defects. Many sporadic cases occur in other breeds of dogs, most often in males. Many affected dogs, including most of the hairless breeds, have patchy or pattern hairlessness as well as associated dental anomalies. All animals with abnormal follicular development are prone to clogged hair follicles, hair follicle infections, and hair foreign-body inflammations.

In dogs, there are several types of abnormalities in hair follicles. A syndrome known as color dilution alopecia is associated with the gene that turns normally black or liver-colored hair blue, beige, or fawn. This syndrome is best known in Doberman Pinschers but is also commonly seen in color dilute Dachshunds, Italian Greyhounds, Greyhounds, Whippets, Yorkshire Terriers, German Shepherds, silver Labrador Retrievers, and tricolor hounds. Affected dogs are born with normal hair coats but before 1 year of age begin to develop hair follicle inflammation and progressive hair loss in the blue or fawn-colored areas. Black hair follicle dysplasia develops earlier with more complete hair loss in black and white dogs. It develops shortly after birth and affects only the black-colored areas. This syndrome is most common in Papillons and Bearded Collies, and is inherited in Large Munsterlanders. Seasonal flank alopecia can appear in Boxers and Airedale Terriers. Various woolly syndromes and post-clipping alopecia can occur in Spitz-type breeds. Reduced hair growth in Irish Water Spaniels develops at 2 to 4 years of age. Another condition called alopecia X occurs in Pomeranians and other breeds.

There are syndromes in which skin cells grow abnormally, resulting in scaling and thickening of the top layer of skin. Some of these syndromes are associated with various other inherited conditions and may be sex linked. Some involve only localized portions of the skin while others produce generalized signs.

Canine ichthyosiform dermatoses occur sporadically in a number of breeds, including Doberman Pinschers, Rottweilers, Irish Setters, Collies, English Springer Spaniels, Cavalier King Charles Spaniels, Golden Retrievers, Labrador Retrievers, American Bulldogs, and terriers (including Jack Russell Terriers). There is good evidence of a familial inheritance pattern for this condition in Jack Russell Terriers and Golden Retrievers. In dogs with ichthyosiform dermatosis, the body is covered with large scales that may flake off in large sheets. The nose and paws may be noticeably thickened with apparent discomfort. Treatment is difficult, but signs may be lessened with special shampoos or solutions. Some experimental treatments have been useful. Control of secondary infection is frequently required. Your veterinarian will prescribe the most appropriate treatment for your pet.

Familial footpad hyperkeratosis is a syndrome reported in Irish Terriers and Dogues de Bordeaux. Hyperkeratosis is increased thickness of the hard, outer layer of the skin. All footpads are involved starting at an early age. The disease is not usually present at birth (congenital). When the hyperkeratosis is severe, horns, cracks (fissures). and secondary infections cause pain and lameness. No other skin abnormalities are present. Treatment concentrates on relief of signs and often includes soaking footpads, applying softening lotions, and treatment of any bacterial infections.

Granulomatous sebaceous adenitis destroys the oil glands and, in some breeds of dogs, is associated with a severe oil discharge and hair loss. It is hereditary in Standard Poodles and possibly in Akitas. It first appears when the dog is a young adult. Noticeable skin thickening precedes the loss of normal hair kinkiness and progresses to patchy hair loss. Akitas tend to have more oiliness and less hair loss than Poodles. Response to treatment is inconsistent and incomplete. Mildly affected dogs are treated with medicated shampoos. Secondary infections are treated as needed. A medication called modified cyclosporine A may also be effective. Sudden resolution of signs has also been seen in some dogs.

Hereditary congenital follicular parakeratosis is a newly recognized syndrome affecting female Rottweilers and female Siberian Huskies. This is a severe defect of the process that forms the keratins that are a major component of skin. This syndrome is associated with various abnormalities in other areas of the body. Little is presently known about this syndrome.

Psoriasiform-lichenoid dermatosis affects young English Springer Spaniels. It is presumed that this syndrome is inherited (genetic in origin). The most obvious signs are red symmetric abnormalities consisting of small lumps on the skin and solid elevated areas near the ears or groin. The abnormalities are covered with scale and become increasingly thick and hard (hyperkeratotic) if left untreated. In some dogs, the abnormalities may eventually spread. Spontaneous improvement occurs in some dogs while in others, the signs come and go. In some dogs, antibiotic treatment or other medications provide relief. In most cases, however, psoriasiform-lichenoid dermatosis does not respond to treatment.

Some skin color abnormalities may be acquired while others may be hereditary. Abnormalities in skin and coat color are sometimes related. Some of the associations are mentioned in hereditary hair loss (see above).

Albinism is rare in dogs. True albinism is always associated with pink or pale irises and with visual defects. Albinism is different from extreme white spotting. In either case, affected animals are at increased risk of skin cancer from solar radiation, especially in areas with short or thin hair. Some animals with extreme piebaldism (spotted or blotched with black and white) or dominant white have associated neurologic anomalies or deafness in one or both ears. In dogs, deafness may also be associated with merle hair coats and is found in Dalmatians, Sealyham Terriers, harlequin Great Danes, Collies, and white Bull Terriers. Rhodesian Ridgebacks with a pale coat color have an association with neurologic disease (specifically, cerebellar degeneration).

Vitiligo is hereditary but not noticeable at birth. The onset is usually in young adulthood. Affected dogs develop bleached splotches of skin that occasionally also affects the hair coat and claws. Most splotches are on the face, especially the bridge of the muzzle or around the eyes. Color loss may come and go with varying amounts of severity. Vitiligo runs in some dog families, especially Belgian Tervurens and Rottweilers. Complete remission may occur but is rare. Vitiligo causes no other health problems. No treatment is available. Treatments used in people with vitiligo are unlikely to help animals.

Acquired aurotrichia is a syndrome seen in some lines of Miniature Schnauzers and occasionally in other breeds of dogs. In affected dogs, the hair along the middle of the back above the spine changes from the normal black or gray to golden. This usually starts in young adulthood. The change may be associated with a thinning of the hair coat. In many cases, there are no other changes to the skin and no other whole-body signs. In most dogs, the coat color returns to normal within 1 to 2 years.

Some skin diseases are genetic defects that affect the integrity or continuity of the skin.

Cutaneous asthenia (also called dermatosparaxis or Ehlers–Danlos syndrome) is a condition in which the skin does not produce enough collagen. This causes loose, stretchy, fragile skin, and joint problems. The fragile skin is evident from birth. Wounds heal slowly or not completely. Skin hangs from the body. Cysts and bruising may develop. The disease is not fatal in dogs. Older animals develop hanging folds of skin and exhibit extensive scarring. Some have joint and eye problems. Diagnosis is based on visible signs and biopsies to evaluate the collagen structure. For cats and dogs, a skin extensibility index has been developed to help your veterinarian diagnose this syndrome. There have been some reports of improvement for affected dogs following vitamin C supplements, and your veterinarian will be able to determine whether such supplements might help your pet.

Epidermolysis bullosa syndromes are a group of hereditary congenital defects that affect the attachments between the outer and inner layers of the skin, resulting in blistering of the skin. The several forms of epidermolysis bullosa have been reported in Collies, Shetland Sheepdogs, Toy Poodles, German Shorthaired Pointers, Golden Retrievers, Akitas, mixed breed dogs, and possibly Beaucerons. Minor skin trauma results in separation of the skin layers. Blisters form and soon rupture, leaving glistening, flat ulcers. Blisters may be present at birth or develop within the first weeks of life. The most severe blisters are on the feet, mouth, face, and genitals. In many cases the disease is fatal.

Cutaneous mucinosis is thought to be a familial problem in some lines of Chinese Shar-Peis. Normal Shar-Peis have more of a protein called mucin than other dogs. In some young dogs, mucin is so excessive that the skin exhibits pronounced folding and blisters. Diagnosis is by skin prick of the blisters or by skin biopsy. As these dogs mature, the syndrome may become less severe. However, this condition can be exaggerated by the development of allergic skin disease, which is common in the breed.

Familialdermatomyositis is an inflammatory disease of the skin and muscles of young Collies and Shetland Sheepdogs. Problems with blood vessels of the skin and muscles occur in the early inflammatory stages of the disease, leading to decreases in size or wasting (atrophy) of those tissues. The onset is typically at younger than 6 months of age. The disease is variable, and individual pups within a litter may be affected differently. Ulcers, crusting, and hair loss appear on the face, ear tips, tail tip, and legs. Heat, sun exposure, and wounds worsen the condition. The muscles most affected are on the head and legs. Diagnosis is established by evaluation of littermates and family history, skin biopsy, electromyography, and muscle biopsy, which must be performed early in the course of the disease. Steroids, pentoxifylline, vitamin E, and omega-3 fatty acids may help. Severely affected dogs rarely respond well to treatment.

Familialvasculopathy has been described in German Shepherds and Parson Russell Terriers. In these dogs, skin ulcers develop shortly after the first set of puppy vaccinations and worsen after subsequent vaccinations. The main signs are footpad swelling and loss of color that may progress to ulcers. All footpads are typically affected. Crusting and ulcers on ear and tail tips and loss of color of the bridge of the muzzle may also occur. As the dogs mature, the disease may go away, but pad ulcers may be so severe that euthanasia is warranted. No known treatment is uniformly effective, although some dogs appear to respond to high dosages of steroids. A severe form of neutrophilic vasculitis has recently been described in young Chinese Shar-Peis; this may be inherited.

Hereditary lupoid dermatosis is a condition reported in German Shorthaired Pointers. The condition is usually first noted when the dog is about 6 months old. The first signs are scaling and crusting on the head and upper parts of the body and legs. This quickly progresses to a generalized scaling of the skin accompanied by redness (erythema) caused by congestion of the tiny blood vessels (capillaries) in the skin. This skin condition is either painful or itchy for the affected animal. These dogs develop fevers and enlarged lymph nodes. Some dogs develop digestive disease and lose weight. When examined in a laboratory, skin biopsy samples show signs of a lupus-like skin condition. This disease is progressive and ultimately fatal. No successful treatment has been reported.

Hereditary zinc deficiency syndromes occur in some breeds. In white Bull Terriers, lethal acrodermatitis includes signs such as poor growth, thickened skin on the legs, and pustules around mucous membranes. These signs are apparent by 10 weeks of age and are later accompanied by diarrhea, pneumonia, and death before 2 years of age. The lives of affected dogs can be prolonged by treating secondary infections. These dogs do not respond to zinc treatment given by mouth. In Alaskan Malamutes, Huskies, and German Shorthaired Pointers, zinc-responsive dermatopathy is responsive to supplemental zinc. Signs develop at weaning or later and include crusted, thickened skin on the legs and around mucous membranes. Often, females develop signs associated with their heat cycle or whelping and lactation. Secondary infections are common. Diagnosis is by skin biopsy and response to zinc supplementation by mouth.

Dogs are rarely born with skin tumors. Some lines of German Shepherds can develop nodular dermatofibrosis, which results in multiple pigmented masses on the skin (called nevi). Growths that form on the feet can develop sores or cause foot deformities or limping. The growths develop during adulthood and indicate the presence of other types of tumors in internal organs, such as the kidneys or uterus.

Also see professional content regarding congenital and inherited skin disorders in dogs.