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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.
Structural follicular dysplasia varies by breed but all involve weakened hairs that break easily. Hair loss is originally seen in areas of repeated grooming or trauma, for instance the neck because of contact with a collar. Hair regrowth may occur, but the hair will be even weaker and the pattern will repeat. The dogs are affected between the ages of two to four years, and it is most commonly seen on the back towards the tail. Progression of the hair loss to cover the trunk can occur.
In some breeds hair follicles in certain parts of the body become progressively miniaturized, analogous to what occurs in male pattern baldness in humans. It is most commonly seen in Dachshunds, Miniature Pinschers, and Chihuahuas. [3] Affected areas become progressively more alopecic. The pattern of hairlessness that results is somewhat breed-dependent and sex dependent. In short-coated toy and miniature dogs, ventral neck, ventral chest, ventral abdomen and inner thighs are affected. In males, the pinnae (ear flaps) are affected. In Greyhounds, the thighs are affected as well as the ventral chest and abdomen.
Cyclic follicular dysplasia is also known as seasonal alopecia.
It causes bilateral hair loss and hyperpigmentation of the flanks. The disease usually starts in the late fall or early spring, and can regrow in about six months, although the hair may be different in color or texture. Treatment with melatonin may result in hair regrowth sooner, so it is thought that the amount of daylight influences this condition. The dogs are affected between the ages of two to four years. [2]
Follicular lipidosis is a type of follicular dysplasia found in the Rottweiler and other red point dogs. [4] It usually occurs before the age of nine months and involves loss of some of the mahogany or red hair of the face and feet. It is caused by lipid invasion of the hair follicle cells.[ citation needed ]
Color dilution alopecia is caused by a dilution gene affecting eumelanin. It is an inherited type of follicular dysplasia. It most commonly affects dogs with blue or fawn coats, which are dilutions of black and brown, respectively Dilution is caused by irregularities in melanin transfer and storage. Melanosomes may clump within melanocytes of the skin and hair follicles, causing the hair shafts to easily fracture. [5] Signs of color dilution alopecia include hair loss and recurrent skin infection on the back. It can involve the whole body. The condition starts between the ages of six months and two years, depending on the degree of dilution. [6] Early hair loss occurs due to hair breakage, making it similar to structural follicular alopecia. It is important to treat the skin infections, and etretinate has been used to treat the hair loss.
In several dog breeds but also in mongrels, dogs with the predisposition due to their coat genetics with the MLPH gene (melanophilin) suffer from colour dilution alopecia (CDA). Interestingly in Great Danes and Weimaraners there are usually no problems due to the dilution gene. The reasons for this are not yet known. [7]
The Siberian Husky and Alaskan Malamute have a type of follicular dysplasia that occurs between the ages of three and four months, possibly later in the Malamute. The guard hairs of the trunk are progressively lost and the coat turns reddish in color.
In black or red Dobermanns, Miniature Pinschers, and Manchester Terriers there is a type of follicular dysplasia that occurs between the ages of one and four years. It begins in the flank and spreads to the back. [2]
Black hair follicular dysplasia occurs in piebald dogs and causes hair loss in black-haired areas soon after birth. It is most commonly seen in Papillon (dog), Gordon setter, Saluki and Bearded Collie, [10] and is known to occur in Large Münsterländer dogs. [11] It is considered to be similar to color dilution alopecia and is inherited as an autosomal recessive trait. [12]
The dachshund, also known as the wiener dog or sausage dog, badger dog and doxie, is a short-legged, long-bodied, hound-type dog breed. The dog may be smooth-haired, wire-haired, or long-haired. Coloration varies.
The Shetland Sheepdog, also known as the Sheltie, is a breed of herding dog that originated in the Shetland Islands of Scotland. It was formally recognized by The Kennel Club in 1909. It was originally called the Shetland Collie, but this caused controversy amongst Rough Collie breeders of the time, so the name was changed. It is a small dog, clever, vocal, willing to please, and trustworthy.
The Affenpinscher is a German breed of small toy dog of Pinscher type. Originally developed as a mouser, the Affenpinscher is now commonly found as a companion worldwide.
The Yorkshire Terrier, also known as a Yorkie, is a British breed of toy dog of terrier type. It is among the smallest of the terriers and indeed of all dog breeds, with a weight of no more than 3.2 kg (7 lb). It originated in the nineteenth century in the English county of Yorkshire, after which it is named. The coat is tan on the head and dark steel-grey on the body; no other colour is accepted by either The Kennel Club or the Fédération Cynologique Internationale.
The Miniature Schnauzer is a breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. Miniature Schnauzers may have been developed from the smallest specimens of the Standard Schnauzer, or crosses between the standard and one or more smaller breeds such as the Affenpinscher, Miniature Pinscher, and Poodles, as farmers bred a small dog that was an efficient ratting dog. They are described as "spunky" but aloof dogs, with good guarding tendencies without some guard dogs' predisposition to bite. Miniature Schnauzers are recognized in four colors internationally: solid black, black and silver, salt and pepper, and white.
Fox Terriers are two different breeds of the terrier dog type: the Smooth Fox Terrier and the Wire Fox Terrier. Both of these breeds originated in the 19th century from a handful of dogs who are descended from earlier varieties of British terriers, and are related to other modern white terrier breeds. In addition, a number of breeds have diverged from these two main types of fox terrier and have been recognised separately, including the Jack Russell Terrier, Miniature Fox Terrier and Rat Terrier. The Wire and Smooth Fox Terriers share similar characteristics, the main differences being in the coat and markings. They have been successful in conformation shows, more prominently in America than their homeland.
The West Highland White Terrier, commonly known as the Westie, is a breed of dog from Scotland with a distinctive white harsh coat with a somewhat soft white undercoat. It is a medium-sized terrier, although with longer legs than other Scottish breeds of terrier. It has a white double coat of fur which fills out the dog's face, giving it a rounded appearance.
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.
A dilution gene is any one of a number of genes that act to create a lighter coat color in living creatures. There are many examples of such genes:
The Cairn Terrier is a terrier breed originating in the Scottish Highlands and recognised as one of Scotland's earliest working dogs.
Demodicosis, also called Demodex folliculitis in humans and demodectic mange or red mange in animals, is caused by a sensitivity to and overpopulation of Demodex spp. as the host's immune system is unable to keep the mites under control.
The Giant Schnauzer is a breed of dog developed in the 17th century in Germany. It is the largest of the three breeds of Schnauzer—the other two breeds being the Standard Schnauzer and the Miniature Schnauzer. Numerous breeds were used in its development, including the black Great Dane, the Bouvier des Flandres, and the German Pinscher. Originally bred to assist on farms by driving livestock to market and guarding the farmer's property, the breed eventually moved into the city, where it worked guarding breweries, butchers' shops, stockyards and factories. It was unknown outside of Bavaria until it became popular as a military dog during World War I and World War II.
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 Bull Terrier is a breed of dog in the terrier family. There is also a miniature version of this breed which is officially known as the Miniature Bull Terrier. This breed originates in 19th century England. Originally bred for vermin control and bloodsports, this breed can be independent and stubborn.
The English Miniature Bull Terrier is a breed with origins in the extinct English White Terrier, the Dalmatian and the Bulldog. The first existence is documented in 1872 in The Dogs of British Island.
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.
The Dobermann is a German breed of medium-large domestic dog of pinscher type. It was originally bred in Thuringia in about 1890 by Louis Dobermann, a tax collector. It has a long muzzle and – ideally – an even and graceful gait. The ears were traditionally cropped and the tail docked, practices which are now illegal in many countries.
Familial renal disease is an uncommon cause of kidney failure in dogs and cats. Most causes are breed-related (familial) and some are inherited. Some are congenital. Renal dysplasia is a type of familial kidney disease characterized by abnormal cellular differentiation of kidney tissue. Dogs and cats with kidney disease caused by these diseases have the typical symptoms of kidney failure, including weight loss, loss of appetite, depression, and increased water consumption and urination. A list of familial kidney diseases by dog and cat breeds is found below.
Dogs have a wide range of coat colors, patterns, textures and lengths. Dog coat color is governed by how genes are passed from dogs to their puppies and how those genes are expressed in each dog. Dogs have about 19,000 genes in their genome but only a handful affect the physical variations in their coats. Most genes come in pairs, one being from the dog's mother and one being from its father. Genes of interest have more than one expression of an allele. Usually only one, or a small number of alleles exist for each gene. In any one gene locus a dog will either be homozygous where the gene is made of two identical alleles or heterozygous where the gene is made of two different alleles.