A dwarf cat (sometimes nicknamed a sausage cat [1] ) is a domestic cat with dwarfism due to rare genetic mutations causing a disproportionate feline body and significant health problems. Unlike undersized cats of normal proportions, dwarf cats suffer from the genetic mutations osteochondrodysplasia and achondroplasia (a form of osteochondrodysplasia). These genetic disorders of bone and cartilage are typically manifested as abnormal bone shape, poor growth or lack of growth, bowing of the limbs to the side – front legs are more likely to be affected, and spinal malformations.
The breeding of dwarf cats is prohibited in several countries and states, due to the animal’s welfare concerns. Furthermore, except from TICA, all other major cat registries do not recognize nor allow the crossbreeding with dwarf cats.
The dwarf cat is recognized by its characteristically short legs, they are chondrodysplastic and have much shorter and thicker legs than the average cat. Because of their health problems and abnormal bone growth, these cats typically lead a shorter life of 12–15 years. [2] Dwarf cats often suffer from spinal disorders, such as lordosis (excessive curvature of the spine) and pectus excavatum (hollowed chest). [3] In regards to behavior, dwarf cats may be no different from the average cat. They can be playful, curious, and fast.
Cats with dwarfism have become significantly popular, but breeding dwarf cats has been viewed as unethical due to the lifelong health results. Dwarf cats became famous worldwide due to the social media spread by famous internet cats with dwarfism, such as Grumpy Cat and Lil Bub.
The term "dwarf cat" is incorrectly applied to cats such as Toy and Teacup Persians which, though small, are breeds of normal feline proportions. [4]
The Munchkin cat is breed of cat characterized by its short legs. The Munchkin is the original breed of dwarf cats. The International Cat Association (TICA) gave recognition to the Munchkin as a breed in 1994. [5] Minuet cats are longhaired dwarf cats, and the name is often used interchangeably with the Napoleon. The Minuet is a cross between the Persian and the Munchkin. The Munchkin is approximately three inches shorter than the average cat. [6] The deformities can lie anywhere in the front legs, affecting the humerus, radius and ulna, and the back legs, affecting the femur, tibia and fibula. [7]
The Munchkin has grown significantly in popularity, but due to ethical concerns, the breed has been banned from registration in show registries, and is therefore primarily bred in the US. [7] Other proposed breeds like the Skookum and Bambino have not been given recognition, although a Sphynx–Munchkin hybrid, the Minskin, is under study. [8] Four other breeds include the Lambkin and the Kinkalow, the Genetta and the Scottish Kilt.
Unlike TICA, all other major cat registries and pet associations do not recognize any dwarf cat as a legitimate breed. The animals are excluded from most major pet shows and contests. Largely an American phenomenon, they are not widely accepted outside of the United States.
In its registration rules, the Fédération Internationale Féline prohibits breeds based on dwarfism, and specifically mentions the Munchkin as an example of unacceptable manipulation of "genetic disease". [10]
In order to protect the animal’s welfare, several countries and states have prohibited breeding of dwarf cats, including the Netherlands (2014), [7] [11] and Victoria (Australia). [12] The Australian Capital Territory (Australia) government consider the Munchkin breed to be "malformed animals" and the deliberate breeding of them "unacceptable" because of the "genetic health problems associated with such breeding". [13]
They are effectively banned under the European Convention for the Protection of Pet Animals and have been strongly condemned in the British magazine Cat World. In the US itself, the ASPCA admonishes its supporters to "stay vigilant" against the small but spreading market. [14]
To determine of a cat has feline dwarfism, X-rays, bone samples, and genetic testing can be done. [15] Genetic testing on cats with feline dwarfism is being utilized in human research as well.
Felis Catus 9.0, a reference genome for the cat, was utilized in research to analyze DNA of cats using genome sequencing, genetic linkage, origin of the parents, and genome-wide association studies. [16] Each of these approaches yielded the result of the dwarfism phenotype resting within the area of the B1 chromosome in the cat. An unidentified novel gene was also discovered that controls disproportionate dwarfism. The test requires a sample of blood or a buccal swab to provide the DNA. Different cats are compared to determine if the dwarfism is proportionate or disproportionate. Cats with disproportionate dwarfism are more common and aside from leg deformities, the cat is not known to have many more health problems.
There are many tests that can be run on cats: feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) tests, heartworm tests, fecal tests, blood tests, etc. Depending on the problems a cat is exhibiting, or what concerns the pet owners may have, different, more advanced tests may be ordered. If a cat is showing signs of feline dwarfism, specific testing can be done to determine if dwarfism is the cause, or if another condition, such as congenital feline hypothyroidism, is causing symptoms similar to feline dwarfism.
Dwarfism has the potential to be mistaken as congenital feline hypothyroidism. Signs such as disproportionate dwarfism, skeletal abnormalities, and mental disabilities point to both dwarfism and hypothyroidism. Because of this, proper testing can determine whether the cat is showing signs of hypothyroidism or if there is a deeper issue. [17]
A blood test measures the levels of thyroid-stimulating hormone (TSH) in the cat can be performed to rule out feline dwarfism. The test checks the levels of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) and will determine if the cat has hypothyroidism, or if further testing needs to be done to come to a different diagnosis. [18]
In 2018, a study was performed on a 10-month-old kitten showing signs of disproportionate dwarfism. Testing was performed on the (TSH), which confirmed hypothyroidism in the kitten. [19] The kitten was prescribed thyroid hormone supplementation and after 22 months, presented as an average, healthy cat. Once diagnosed, thyroid hormone supplementation should start as early as possible.
The Bengal cat is a breed of hybrid cat created from crossing of an Asian leopard cat, with domestic cats, especially the spotted Egyptian Mau. It is then usually bred with a breed that demonstrates a friendlier personality, because after breeding a domesticated cat with a wildcat, its friendly personality may not manifest in the kitten. The breed's name derives from the leopard cat's taxonomic name.
The Sphynx cat also known as the Canadian Sphynx, is a breed of cat known for its lack of fur. Hairlessness in cats is a naturally occurring genetic mutation, and the Sphynx was developed through selective breeding of these animals, starting in the 1960s.
The Scottish Fold is a distinctive breed of domestic cat characterised by a natural dominant gene mutation associated with osteochondrodysplasia. This genetic anomaly affects cartilage throughout the body, causing the ears to "fold", bending forward and down towards the front of the head. While this trait contributes to the breed's unique appearance, often described as "owl-like", it has negative effects on the cats' welfare.
The Munchkin is a breed of cat characterized by its very short legs, which are caused by genetic mutation. Compared to many other cat breeds, it is a relatively new breed, documented since 1940s and officially recognized in 1991. The Munchkin is considered to be the original breed of dwarf cat.
The Devon Rex is a tall-eared, short-haired breed of cat that emerged in England during the late 1950s. The breed is known for its atypical appearance, with an oddly shaped head, large eyes, and the short and wavy coat.
The Burmese cat is a breed of domestic cat, originating in Burma, believed to have its roots near the Thai-Burma border and developed in the United States and Britain.
The Siberian is a centuries-old landrace of domestic cat in Russia, and recently developed as a formal breed with standards promulgated the world over since the late-1980s. Since 2006, the breed is recognised for registry and championship status with all major cat registries.
The Donskoy cat, also known as Don Sphynx or Russian Hairless, is a hairless cat breed of Russian origin. It is not related to the better-known Sphynx cat whose characteristic hairlessness is caused by a recessive mutation in the keratin 71 gene. The Donskoy's hairlessness, on the other hand, is caused by a dominant mutation.
The International Cat Association (TICA) is considered the world's largest genetic cat registry. Originally a North American organization, it now has a worldwide presence. The organization has a genetic registry for pedigreed and household pet cats and is one of the world's largest sanctioning bodies for cat shows.
The Peterbald is a hairless cat breed of Russian origin. It was created in St. Petersburg in 1994 from an experimental cross of a Don Sphynx and an Oriental Shorthair. They have an Oriental build with a dominant hair-losing gene. The breed was accepted for Championship status in 2009.
The Neva Masquerade is a breed or sub-breed of long-haired domestic cat, which originates in Russia. It is the sister breed or colourpoint variant of the Siberian cat, a centuries-old Russian landrace. The colourpoint markings are the result of a colourpoint gene originally found in Siamese cats. The Neva Masquerade is believed to be derived from crossing the Siberian cat with Asian colourpoint cats, such as the Siamese or Thai, or possibly cats related to those, such as the colourpointed Persian cats. Some cat registries may classify the Neva Masquerade as a colourpoint variety or sub-breed of the Siberian cat, while others consider it to be a separate sister breed. Regardless of its classification, all Neva Masquerade cats are selectively bred and pedigreed today in all major cat fancier and breeder organisations under the Siberian (Forest) cat or Neva Masquerade. This means that all Neva Masquerade cats are purebred cats with a formally registered ancestry.
A cat registry or cat breed registry, also known as a cat fancier organization, cattery federation, or cat breeders' association, is an organization that registers domestic cats of many breeds, for exhibition and for breeding lineage tracking purposes. A cat registry stores the pedigrees (genealogies) of cats, cattery names, and other details of cats; studbooks, breed descriptions, and the formal breed standards ; lists of judges qualified to judge at shows run by or affiliated with that registry, and sometimes other information. A cat registry is not the same as a breed club or breed society. Cat registries each have their own rules and usually also organize or license (sanction) cat shows. The show procedures vary widely, and awards won in one registry are not normally recognized by another. Some registries only serve breeders, while others are oriented toward pet owners and provide individual as well as cattery memberships, while yet others are federations only deal with breed clubs or even other registries as intermediaries between the organization and breeders.
The Minskin is a breed of cat derived from intentional cross-breeding between the Munchkin and Burmese cat breeds, with the addition of Sphynx and Devon Rex. It is a mostly-hairless breed of cat
The Minuet is a hybrid mix of Persian and Munchkin cat breeds. Categorized by The International Cat Association (TICA) as a domestic hybrid, "developed from a deliberate cross between two existing domestic breeds, incorporating characteristics of both parental breeds into the new mix." The Minuet cat is characterized by its short legs, as a result of the dwarfism-mutation derived from the Munchkin breed.
The Persian cat, also known as the Persian Longhair, is a long-haired breed of cat characterised by a round face and short muzzle. The first documented ancestors of Persian cats might have been imported into Italy from Khorasan as early as around 1620, however, this has not been proven. Instead, there is stronger evidence for a longhaired cat breed being exported from Afghanistan and Iran from the 19th century onwards. Persian cats have been widely recognised by the North-West European cat fancy since the 19th century, and after World War II by breeders from North America, Australia and New Zealand. Some cat fancier organisations' breed standards subsume the Himalayan and Exotic Shorthair as variants of this breed, while others generally treat them as separate breeds.
The Lykoi is a breed of cat derived from a natural mutation causing a form of hypotrichia found in domestic short-haired cats. The mutation has occurred in domestic cats over the last 20 years. DNA testing has been done by UC Davis to confirm that the cats do not carry the Sphynx/Devon Rex gene. The breed was developed by Brittney Gobble in Vonore, Tennessee.
The Foldex cat, also known as the Exotic Fold, is a breed of cat developed in the Canadian province of Quebec. The breed is recognized by one cat registry, the Canadian Cat Association. The foundation stock of the breed is the Scottish Fold and the Exotic Shorthair. Foldexes are medium-sized cats with a rounded face, short legs, and folded ears. The latter are the defining feature of the breed. Their eyes are well-rounded and wide open, with pair of ears with small and smooth-edged tips. They are described as intelligent and sweet. They were first registered as New Breed by the Canadian Cat Association in 2006 and then finally granted the Championship status in 2010.
Hypothyroidism is an endocrine disorder in which the thyroid gland fails to produce sufficient thyroid hormones. Hypothyroidism is one of the most common endocrinopathies in dogs. It is either acquired or congenital.
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