Alopecia X is a type of adult-onset alopecia in dogs previously known by many other names. The condition was first described in 1977. The condition is believed to be caused by a genetic predisposition to a hormone defect. Often dogs will recover after neutering. [1] [2]
The condition was previously known under multiple names including: adult-onset growth hormone deficiency, growth hormone responsive alopecia, castration responsive alopecia, biopsy responsive alopecia, black skin disease, and congenital adrenal hyperplasia-like syndrome. Today it is known as Alopecia X which reflects the unknown origin of the disease. [3]
The cause is not unknown. [2] [3] One theory of a growth hormone deficiency being the cause was abandoned when multiple studies showed normal growth hormone responses following stimulation and normal IGF-1 levels in affected dogs. Why some dogs with alopecia X show a suppressed growth hormone response remains unknown. [3] Mild hypercortisolism has been suggested as a cause of alopecia X in miniature Poodles and Pomeranians. [3]
Initial signs of alopecia X are hair loss around the collar and rear thighs that slowly progresses to near complete alopecia of the trunk, neck, and proximal legs. The head, distal legs, and distal tail do not experience alopecia. In some cases a sparse wooly coat will remain. Hyperpigmentation develops simultaneously; however it may not occur, especially in white-coated Poodles. Aside from this clinical affects are not notable. [3]
Diagnosis is done via the exclusion of endocrinopathies, including: hypercortisolism, hypothyroidism, hyperestrogenism, and hyperprogesteronism (a rare condition in some adrenocortical or testicular tumours), as well as other conditions such as, cyclic flank alopecia, follicular dysplasia, and sebaceous adentitis. A skin biopsy will typically show the same changes as other endocrinopathies. There is no way to consistently and reliably differentiate alopecia X from other conditions. However 'flame follicles' — which are spikes of fused keratin that seem to protrude through the outer root sheath to the vitreous layer that creates a type of 'fiery' effect — appear to be more common in alopecia x than other dermatopathies. [3]
Various treatments have been used to treat alopecia X, such as: growth hormones, castration, melatonin, mitotane, and trilostane. Treatment is not always effective, and because hair cycle arrest is a 'cosmetic' disease the risk of treatment needs to be compared to the benefit. [3]
Congenital iodine deficiency syndrome (CIDS) is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It is one cause of underactive thyroid function at birth, called congenital hypothyroidism, historically referred to as cretinism (obsolete). If untreated, it results in impairment of both physical and mental development. Symptoms may include goiter, poor length growth in infants, reduced adult stature, thickened skin, hair loss, enlarged tongue, a protruding abdomen; delayed bone maturation and puberty in children; and mental deterioration, neurological impairment, impeded ovulation, and infertility in adults.
Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress.
The Poodle, called the Pudel in German and the Caniche in French, is a breed of water dog. The breed is divided into four varieties based on size, the Standard Poodle, Medium Poodle, Miniature Poodle and Toy Poodle, although the Medium Poodle is not universally recognised. They have a distinctive thick, curly coat that comes in many colors and patterns, with only solid colors recognized by breed registries. Poodles are active and intelligent, and are particularly able to learn from humans. Poodles tend to live 10–18 years, with smaller varieties tending to live longer than larger ones.
Dihydrotestosterone is an endogenous androgen sex steroid and hormone primarily involved in the growth and repair of the prostate and the penis, as well as the production of sebum and body hair composition.
Phosphofructokinase deficiency is a rare muscular metabolic disorder, with an autosomal recessive inheritance pattern.
POEMS syndrome is a rare paraneoplastic syndrome caused by a clone of aberrant plasma cells. The name POEMS is an acronym for some of the disease's major signs and symptoms, as is PEP.
Skin disorders are among the most common health problems in dogs, and have many causes. The condition of a dog's skin and coat is also an important indicator of its general health. Skin disorders of dogs vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment. Skin disorders may be primary or secondary in nature, making diagnosis complicated.
The coat of the domestic dog refers to the hair that covers its body. Dogs demonstrate a wide range of coat colors, patterns, textures, and lengths.
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White dog shaker syndrome causes full body tremors in small dog breeds. It is most common in West Highland White Terriers, Maltese, Bichons, Poodles, and other small dogs. There is a sudden onset of the disease at one to two years of age. It is more likely to occur, and the symptom is worse during times of stress. Nystagmus, difficulty walking, and seizures may occur in some dogs.
Follicular dysplasia is a genetic disease of dogs causing alopecia, also called hair loss. It is caused by hair follicles that are misfunctioning due to structural abnormality. There are several types, some affecting only certain breeds. Diagnosis is achieved through a biopsy, and treatment is rarely successful. Certain breeds, such as the Mexican Hairless Dog and Chinese Crested Dog, are bred specifically for alopecia.
Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs and, more rarely, cats. Similar to retinitis pigmentosa in humans, it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment.
Pattern hair loss is a hair loss condition that primarily affects the top and front of the scalp. In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front hairline, loss of hair on the crown (vertex) of the scalp, or a combination of both. Female-pattern hair loss (FPHL) typically presents as a diffuse thinning of the hair across the entire scalp.
Cat skin disorders are among the most common health problems in cats. Skin disorders in cats have many causes, and many of the common skin disorders that afflict people have a counterpart in cats. The condition of a cat's skin and coat can also be an important indicator of its general health. Skin disorders of cats vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment. Cat skin disorders may be grouped into categories according to the causes.
Anagen effluvium is the pathologic loss of anagen or growth-phase hairs. Classically, it is caused by radiation therapy to the head and systemic chemotherapy, especially with alkylating agents.
Scarring hair loss, also known as cicatricial alopecia, is the loss of hair which is accompanied with scarring. This is in contrast to non scarring hair loss.
Non scarring hair loss, also known as noncicatricial alopecia is the loss of hair without any scarring being present. There is typically little inflammation and irritation, but hair loss is significant. This is in contrast to scarring hair loss during which hair follicles are replaced with scar tissue as a result of inflammation. Hair loss may be spread throughout the scalp (diffuse) or at certain spots (focal). The loss may be sudden or gradual with accompanying stress.
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Alopecia in animals is a condition where locations on the body surface that are typically covered in hair, contain areas where hair is absent, and is a condition that can affect other animals besides humans. Alopecia is a condition that can affect wild organisms and captive organisms, however, the condition tends to be more prominent in captive contexts. Development of alopecia in animals is usually the sign of an underlying disease. Some animals may be genetically predisposed to hair loss, while in some it may be caused by hypersensitivity or nutritional factors. These include Moluccan cockatoos, spectacled bears, hedgehogs, raccoons, squirrels, baboons, and chimpanzees since they share 98% of human genes. Others that are selectively bred to have baldness include rabbits, guinea pigs, Syrian hamsters, mice, rats, and cats. Environmental enrichment has been used in some cases to mitigate certain behaviours that cause hair loss, improve alopecia, and address welfare concerns.