Four eared cats have two ears and four ear flaps

This is a quick note and a cross-post. I am a little irritated by the news media who have recently written about a Tennessee kitten with "four ears". There's lots of excitement within the news media about this. They like anatomical curiosities. It's a bit like the Victorian voyeurism of freaks at freak shows. 

Four eared cats have two ears and four ear flaps. Image: MikeB

But they get it wrong. When a cat has "four ears" they actually have four ear flaps - the bit that we see and which captures sound - but internally they have two middle ears and two inner ears. In other words they have two ears but they have for ear flaps, one extra which is normally much smaller than the original one due to a genetic mutation about which the scientists don't know anything almost because this is quite a rare condition.

That's the picture. I wanted to correct what the newspapers are saying. Because they almost blindly shout from the rooftops that this cat has four ears when he does not. He has two ears because the word "ear" describes the entire anatomy including the ear flap, the middle ear, and the inner ear.

In another act of misrepresentation I would argue, they have called this ginger tabby and white cat with a long face and large ear flaps (possible Oriental Shorter genes somewhere in the) "Audio". That's the opposite to what he should be called because 'audio' means producing sound whereas ear flaps capture sound. Another anomaly!

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P.S. please forgive the occasional typo. These articles are written at breakneck speed using Dragon Dictate. I have to prepare them in around 20 mins.

Why humans don't have tails. Genetic basis for our tail-loss evolution.

Unlike our domestic cat companions we don't have tails. You've probably noticed! 😉😎 But we might have had tails and think how different the world would be if we had retained our tails like our primate cousins. The mind boggles. One's imagination can run riot with that image. All the chairs and all the sofas and all the seats on trains and buses would have to be changed.

Human with a tail in X-ray. Image by DALLE.

RELATED: Evolution of the blotched tabby pattern of domestic cats.

So what happened? Well, firstly, unlike Tucker Carlson, you've got to believe in evolution to believe in this scientific explanation. In fact, I hope Carlson reads this article because it might make him see sense about evolution. He believes that God created humans and animals under the creationist theory. He says there is no evidence for evolution which is wrong but he believes creationism about which there is certainly no evidence whatsoever. Tucker Carlson is irrational.

"It has long been speculated that tail loss in hominoids contributed to orthograde and bipedal locomotion, the evolutionary occurrence of which coincided with the loss of the tail" - quote from the study - see citation at base of page.

The reason

In summary, a genetic parasite altered a crucial gene related to tail development when our lineage diverged from other primates around 25 million years ago. This alteration ultimately led to the disappearance of tails in apes, including humans. Our tailless state owes its existence to this ancient genetic twist.

In some more detail: over millions of years, DNA undergoes changes that drive evolution. One intriguing element is the Alu element, a repetitive DNA sequence found exclusively in primates. These “jumping genes” can insert themselves randomly into the genome, potentially disrupting or enhancing gene function. In this case, the Alu elements reside in the TBXT gene, specifically within introns (DNA sequences flanking exons). Introns were once considered the “dark matter” of the genome, assumed to serve no purpose. However, when cells use the TBXT gene to generate RNA, the repetitive nature of Alu sequences causes them to bind together.

The researchers discovered two Alu elements in the TBXT gene, present in great apes but absent in monkeys. Remarkably, these elements reside in introns, not in the protein-coding exons. When RNA molecules are generated from the TBXT gene, the Alu sequences bind together, potentially influencing tail development.

Now, that is highly technical and I don't fully understand it but that is the current explanation as to why humans don't have tails. You can boil it down to the way evolution works and the way genetic mutations sometimes arise during evolution which leads to the creation of a different kind of animal and that animal does very well in terms of survival and therefore this alteration to the appearance and physiology sticks around and doesn't disappear.

Bo Xia, is the first author of the study (formerly a graduate student at New York University and now a principal investigator at the Broad Institute).

RELATED ARTICLE: Feline Evolution in Brief.

Study Citation

Xia, B., Zhang, W., Zhao, G. et al. On the genetic basis of tail-loss evolution in humans and apes. Nature 626, 1042–1048 (2024). https://doi.org/10.1038/s41586-024-07095-8

P.S. please forgive the occasional typo. These articles are written at breakneck speed using Dragon Dictate. I have to prepare them in around 20 mins.

Berlin police seized 48 illegally bred Levkoy cats considered the product of 'torture breeding' in Germany

Germany has a brilliant nationwide law which states that purebred cats that are bred with inherited genetic diseases causing general pain and suffering are the product of "torture breeding" and they are illegal in the country. 

Levkoy Cay. Image from unknown author.

The word "torture" is a very evocative and strong word and I think it is a brilliant word to describe these breeds which are fully accepted in many other countries including America.

In this instance I'm referring to the Levkoy which is a Ukrainian breed; a hairless cat with floppy ears. Germany has outlawed hairless cats because they don't have a coat 😎😢 and therefore they can't live normal lives. 

You can't change the anatomy of a cat breed that fundamentally in Germany and make the cat more vulnerable without being labelled a torture breeder.

And apparently this man living in Berlin was told to stop breeding the Levkoy cat but he continued nonetheless and in a raid by the police and animal welfare authorities his entire stock of cats were seized and he was arrested. He now faces a substantial fine.

The officials believe that he was probably the last breeder in Germany of the Ukrainian Levkoy cat breed.

The seized cats have been distributed to foster carers across Germany where they have received a check up and veterinary care where needed.

You might like to read about this cat by clicking on the following link. It's an article written by visitor to my website. I have updated that page to include what happened in Germany as described in this article.

Levkoy Cat Breed.

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P.S. please forgive the occasional typo. These articles are written at breakneck speed using Dragon Dictate. I have to prepare them in around 20 mins.

What is this strange looking cat with odd ears?

This picture is on the Reddit.com website and the person who posted it said that this is a 'very rare and strange cat'. It is a strange-looking cat (but not very rare) because the photograph captures nicely, almost in silhouette, the curled-back ears. It looks like everything is against what we normally associate with the domestic cat appearance with their ever-alert ears pointing forwards to collect the sound waves heading towards them.

What is this strange looking cat with odd ears? Image: Reddit.com

Domestic cats have really good hearing, better than human hearing. Their large ear flaps which can rotate around the head thanks to the 30+ muscles controlling the them, help in picking up the soundwaves.

So, when the ears fold back like this it must affect their hearing and it is due to a genetic mutation. It does look very strange and a bit disturbing to be honest. But this is an American Curl purebred cat (probably) and if he is not a pedigree cat, he'll be a random bred version. The purebreds are deliberately created by breeders to be sold to the public.

It's quite a rare purebred cat and not that popular compared, for example, to the Persian or Maine Coon cat breeds.

It gives the cat a kind of devilish look and they come in shorthaired and longhaired varieties. Essentially this cat is a standard random bred cat with curly ears. There is nothing extreme about the cat's appearance.

American Curl cats are born with straight ears and the ear flaps do not curl back as you see in the photograph until the kittens are 2 to 10 days old. The kittens enter a transitional phase that lasts until about 16 weeks of age and during this time the ears begin to change. They may even 'uncurl' or curl more tightly.

The cat in the photograph has particularly curly ears and would be of show cat quality.

RELATED: American Curl Cat: 12 facts.

I've seen American curl ears that don't curl quite so much. The genetic mutation causes the cartilage in the ear flaps to take up this peculiar shape. The mutated gene is dominant.

As mentioned, the ears curl to different degrees and in the 1st° curl version of this cat, only the tips of the ears curl back. These cats are considered to be pet quality which means that they are not going to be show cats. The 2nd° curl of the ears is an arc ranging from 45° to less than 90°. Cats with secondary degree curled may be considered for breeding purposes but they are not of show quality.

Finally, the third-degree curl of the ears is the curliest. The ears curl from 90 to 180° with the tips not touching the back of the ear or the head and pointing towards the center of the base of the skull. Cats with third-degree curl combined with the correct overall look of the cat as per breed standard would be of show quality.

The cat breed was commenced when in June 1981 in Lakewood, California a longhaired silky black female kitten with these strange ears wandered up to the home of Joe and Grace Ruga. They named the stray cat Shulamith. This cat was the foundation cat for the entire breed and they set about creating the breed from thereon.

Six years later The International Cat Association accepted the American Curl longhair for championship status. They are now recognised for championship status in most organisations in North America.

Here is a calico American Curl. Photo by Helmi Flick. The ears are not as impressive.

Mother cat with pom pom tail followed by 6 pom pom tailed kittens marching along roof

Bobtailed mother cat followed by 6 bobtailed kittens marching on roof. Screenshot.

This looks like Asia to me but I am unsure. However, pom pom tailed, short-tailed, bobtailed and kinked tailed cats are not uncommon in Asia; in countries like Thailand. Thailand is meant to be the country of origin of the Siamese cat and a high percentage of Siamese cats used to have kinked tails when they were first imported to the UK. The kink has been bred out of the Siamese but you can still feel the kink. It is part of the breed. A sort of trademark. 

It is an unusual sight to people in the West. It might be fairly common in Asia, however.  There is something nice about the video. Although I am sure their lives are hard as they are community cats; unowned cats. They look as if they are in reasonable condition though. But you hardly ever see pom pom tailed stray cats like this in the UK and I suspect that they are rare in the USA too. Like I said it is an Asian trait. 

Someone will tell me now that the video was made in the USA 😎.

Note: This is an embedded video from another website. Sometimes they are deleted at source or the video is turned into a link which stops it working here. I have no control over this.

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Do Selkirk Rex cats shed a lot?

Do Selkirk Rex cats shed a lot? No, is the answer. There is nothing in the history of this breed which indicates that Selkirk Rex cats shed more or less than other cats. The cat has coarse guard (top coat) hairs and these together with the awn and down hairs are curled.

Curly-coated cat. The Selkirk Rex. Photo: Nathalie Jacques, Saint-Léonard d'Aston, Québec, Canada.

Selkirk Rex kittens are born with curly coats. The coat disappears at about 6-months-of-age. It is replaced by sparse wiry hair. At around ten months old the adult coat emerges which is curly, plush and thick.

There is nothing in the literature which supports the belief that the Selkirk Rex sheds a lot. They neither shed more nor less than cats with normal coats to the best of my knowledge.

Hair shedding in cats is due to the change in the amount of light not the amount of heat. That is why shedding is seasonal with more hair shed in the summer months due to more light.

The gene causing the curly coat is dominant in contrast to the other Rex cats. 'Rex' cats are curly haired cats. The Devon and Cornish Rex cats are also well-known. The Selkirk has gained some popularity recently (2018-2021) because of media coverage of cats with sheep's coats.

Pseudo-melanistic black tiger photographed in Odisha, India

ODISHA, INDIA, NEWS AND COMMENT: A lucky amateur photographer, Soumen Bajpayee, captured a black tiger, more particularly a tiger with thick dark stripes almost covering the tawny/orange background because of a genetic mutation described as pseudo-melanism. These tigers are said to be incredibly rare (as reported by the Daily Mail) which is why the photographer was incredibly lucky. I hope that he was able to sell his photographs for a decent amount of money. They also report that melanistic black tigers are only found in Odisha state and that the numbers have declined dramatically, especially recently according to a 2018 tiger count.

Pseudo-melanistic black tiger in Odisha state India. Photo credit per embossing lower left.

Most black tigers can be seen in the Similipal Tiger Reserve in Odisha. They first reported melanistic tigers in this reserve in 2007. A wildlife expert and scientist at the Wildlife Institute of India said that he believed that there were only 7-8 of these tigers left. They are said to be smaller than the standard-coloured tigers.

There is constant pressure on tiger numbers in India because of the continually growing human population, which squeezes out wildlife. I'm referring particularly to human activity which increases as the human population increases. It makes sense. Human activity is anathema to tigers in the wild.

Sarah Hartwell, an expert on cat genetics and unusual cats both wild and domestic, tells us that pseudo-melanistic tigers might be becoming more common due to inbreeding which in turn is caused by habitat reduction which in turn is caused by, as mentioned, increased human activity.

In the fact that pseudo-melanistic black tigers are smaller than the normal tigers also indicate inbreeding. Inbreeding promotes anomalous coat patterns and/or colours. This is because recessive genes are able to manifest themselves in phenotypes. Also, totally black melanistic tigers have been reported. Sometimes people misidentify a melanistic leopard which is totally black, or very dark charcoal coloured, as a tiger which may account for the assessment that melanistic tigers are smaller.

Sarah reports on some old accounts of black tigers. For example, in an ancient Chinese Encyclopaedia written circa 300 BC called Erya, there is a mention of a black tiger in a chapter headed "Explaining the beasts". It starts "The shu is a black tiger."

The book reports of a small black tiger with fur that was dark and luxuriant but "bore spots/stripes". The Tower of London menagerie which was founded in the 13th century by Henry III at one time had a black tiger from the East Indies it is said, but it is more likely that it was a black leopard.

The Daily Mail report is dated Nov. 2020.

What wild cats are black?

No wild cat species (as a species) is black. Sometimes individual wild cats of some species are black or dark charcoal because of a genetic mutation resulting in melanism. The classic melanistic wild cat is the black jaguar called the black panther. The puma can be black too and so can the bobcat, the serval, the leopard and Geoffroy's cat. These names come out of my head. I have probably forgotten some.

Black leopard (melanistic). Pic: Pixabay.

But the point is that the answer is NONE. It is just that some individuals do end up black against the usual colour of the species concerned because of this genetic mutation.

SEE SOME BLACK PANTHER PICTURES.

Melanism affects many animals of many species, not just some wild cats. For instance melanistic leopards are quite common. They are sometimes bred in zoos. Black leopards are caused by a recessive gene. They are less fertile than normal leopards according to Sarah Hartwell, a cat genetics expert.

Black leopards in captivity may be more highly strung than normal leopards because they are bred to entertain the public and in doing that they become inbred. This affects their mental health. 

As leopards are nocturnal being black does not impede hunting but probably has the opposite effect. Melanistic leopards are also called black panthers.

Siamese Cat Kinked Tail

It was entirely normal for original Siamese cats to have kinked tails. The Siamese cat was referred to as "The Royal Cat of Siam". Mrs Vyvyan who lived in Dover, Kent, UK says that the only purebred Siamese cats in Siam (now Thailand) were at the King's Palace. In other words all the others were not purebred. That makes sense because it was the time of the beginning of the cat fancy and the breeding of purebred cats. Certainly in Siam if a cat was deemed to be purebred is was not assessed as such through cat association records but by observation and/or the cat being confined to a certain area - perhaps the King's Palace.

It is believed, she says, that the original pair that were imported into England came from the Palace and that importation happened with great difficulty because they were rare even in Siam and the king wanted to keep them. Mrs Vyvyan was the person who imported them. She was living in China at the time and the cats reached her in 1886. She brought "the father, mother and a pair of kittens to England". The history of the importation of the Siamese cat is a little muddled so you will see variations on the theme.

She says that, "most of the kittens have a kink in the tail". She goes on to say that the kink varies in its position on the tail; the middle of the tail, close to the body (towards the base of the tail) or towards the tip of the tail forming a "hook".

Mr Harrison Weir, the founder of the cat fancy and the first cat show, says that Mrs Vyvyan's description of the kink tallies with the descriptions of Charles Darwin, the famous naturalist who created the theory of evolution of the species. In his studies and writings he referred to cats with shortened tails.

At page 47 of Mr. Darwin's book, "The Variation of Animals and Plants under Domestication," vol.i, page 47, he writes that throughout the area of the Malayan Archipelago, Siam (Thailand), Pequan (no idea where that is - it's an outdated name) and 'Burmah' (Myanmar) "all the cats have truncated tails about half the proper length, often with a sort of knob at the end".

Darwin also refers to the "Madagascar cat", which he says has a "twisted tail".  This observation is confirmed by another scientist who says that the "Malay cat" has a tail that is half the normal length and contorted into a sort of knot, which cannot be straightened.

Harrison Weir makes the point that the kinked Siamese cat tail is reminiscent of the truncated tails referred to by Darwin. They are both "defects" for want of a better description in a cat's tail. Incidentally Mr Weir also speculates that the Manx cat might have originated in the Malayan short tailed cat.

Clearly in that part of the world, the Far East, a genetic mutation has taken place that was, and probably still is, widespread which affects cats' tails. The genetic mutation that shortens the tail may be linked to the mutation that causes the Siamese cat's tail to kink. I don't know of any science to support that, however.

Breeders in the West, selectively bred out the kinked tail. They did not like it. It did not conform with western notions of beauty. They also modified the appearance of the original Siamese cat to extreme proportions in an attempt to "refine it". I am afraid that they failed in that task as judged by public opinion.

It is interesting to speculate what would have happened if the breeders had decided to keep the kinked tail and made a feature out of it.

Source: there are many sources for this. The main source is Harrison Weir's Our Cats and all about them first published in 1889, now published by Read Country Books.

Cat Body Type Genetic Mutations

People search for "cat body type genetic mutations". So I feel that I should provide a response to what is an enquiry by internet surfers.

The thing is though, that there are no genetic mutations in the cat world, wild or domestic or in between (feral) which cause a change in the body type of the cat. By body type I am referring to the cat fancy's idea of what body type means - for example, cobby or foreign etc. See this page: Cat Body Types for a full description.

Sure, genetic mutations alter aspects of the cats body on very rare occasions (one in a million perhaps) but not the entire body type. By this I mean the overall shape and size of the cat's body.

Examples of where a genetic mutation has changed an element of the cat's body are:

• Manx - lack of tail
• American Curl - ear flaps that curl backwards
• American Ringtail - curly tail
• Scottish Fold - ear flaps that are folded flat to the head
• Dwarf Cats - short legs
• The Rex cats - curly coat (Rex cats are e.g. Cornish Rex, Devon Rex and LaPerm as three examples only. There are more.
• Sphynx - lack of hair
• Peterbald - balding cat!

As you can see the overall body type is not affected.

These genetic mutations have resulted in the creation of new breeds of cat. Variations in cat body type originate in natural evolution, individual cat differences, the sex of the cat and importantly selective breeding by cat breeders.

A classic case of selective breeding that controls cat body type is the teacup cats. These are very small. Breeders breed small cat to small cat and create smaller and smaller cats and fix that trait.



From Cat Body Type Genetic Mutations to Home Page

Genetic Diseases in Purebred Cats

Siamese cat - photo copyright Stockxpert

Purebred cats and mixed-breed cats have a fairly equal propensity to get ill but it is generally considered to be the case that mixed-breed non-purebred non-pedigree cats have a lesser chance of suffering from an inherited disorder or genetic disease (or is this the case actually). This, it is argued, is because of the breeding practices of purebred cat breeders who are obliged (and no criticism is intended) to breed in a way which allows recessive, defective, genes that would otherwise stay dormant to become effective and visible. What I mean is that breeding purebred cats has to be to type (appearance) which requires a degree of inbreeding and a narrowing of the gene pool resulting in an "increased expression"² of unhealthy recessive traits and, therefore a corresponding increase in the incidence of occurrence of these disorders. That said random bred cats also suffer from these diseases.

Clearly two "players" in the process of breeding cats, the cat breeders themselves and the cat associations (in respect of setting breed standards and good practice) require a good understanding of basic genetics, inheritance "patterns" and the practice of breeding for there to be successful breeding that does not negatively impact on the cat.

Note: The source is primarily a rather scarce book called: Medical, Genetic, & Behavioral Aspects of Purebred Cats; Ross D.Clark, DVM, Forum Publications, Fairway Kansas, 1992 (referred to as book 1)

Another respected source is The Cat, Its Behavior, Nutrition, Health by Linda P Case. Published by Blackwell Publishing ISBN 978-0-8138-0331-9 (referred to as book 2) 

Please also note that this page is not "breeder bashing". I am fine about cat breeders. But I just like writing about what really happens. I like a bit of reality.

Cats, like any other species can suffer from inherited diseases from defective and sometimes fatal genes. Polygenetic inheritance appears to be the cause of many genetic defects, which makes it difficult to see established patterns. As diseases transmitted by dominant genes often have "extreme effects"² causing the offspring to die in the womb or soon after birth, most inherited genetic defects are due to recessive genes. Some breeds suffer from inherited diseases with greater frequency than other breeds.

Apparently, there are a total of 150 genetic disorders that can affect cats. I am not sure if that is all cats (meaning including wildcats) or only domestic cats. There are 400 genetic disorders that can affect dogs. The breeding programs of some dog breeds has been criticized causing the break up of long term business relationships at the Kennel Club in the UK (see purebred pedigree cat breeding ). Apparently humans can suffer from thousands of possible inherited disorders (src: www.pandecats.com - I don't know how reliable this source is).

However a Wikipedia® article on human genetic diseases lists over 750. This is interesting. If the figures for cats is accurate it is only a fraction of the number of genetic disorders that occur in people. This is a strong counter argument to one which says that purebred cat breeding can promote ill health because of greater incidences of genetic diseases in purebred cats. However, one factor that is not discussed here is the number of occurrences of the genetic diseases set out below and those set out on the Wikipedia® website. Also there will have been much more funding into genetic diseases in humans so it could reasonably be expected that there are more Genetic Diseases in Purebred Cats or cats generally than as stated above especially as there is a lot of similarity between cat anatomy and human anatomy at a fundamental level.

Although, on the face of it the number of genetic diseases in purebred cats is much lower than the number affecting humans, it might be the case that the occurrences of the genetic diseases in purebred cats is much higher. This might modify the counter argument.This is where the research comes to a stop as research into genetic disease in cats is work in progress. There is some funding but it might be fair to say that it is somewhat limited. I wonder how much funding goes into research on genetic illnesses compared to the disposal and/or recycling of euthanized feral and homeless cats? This is an upsetting area and comparison but one which informs us about ourselves and our deep rooted attitudes in a general sense towards other animals.

Another point that comes to mind is this. The list below refers to 20 cat breeds. There are over 70 listed on the home page of this website. Does that mean the other breeds do not suffer from genetic diseases in purebred cats? I think not. In fact I know not. The conclusion is that this list is not complete but it is still a lot fuller than is commonly available, I believe. In fact I have added to the list. The added diseases are in italics. These are added to the list from the source referred to at the base of the post.

The list of Genetic Diseases in Purebred Cats is interesting in another way. The cat breed with the highest number of genetically linked diseases is the Siamese cat (Modern Siamese). Also see Siamese Cat Health Problems (a full discussion). There are a wide range of types (conformations) of this cat breed, from the more standard looking cat, the traditional to the Classic looking cat, which I say is like the new breed called the Thai to the extreme Modern Siamese, a very slender cat. I don't know to which conformation the list refers. Perhaps it simply refers to the Siamese cat generally not making a distinction. Paradoxically the Siamese cat is one of the most popular cat on the basis of a long running poll on the Pictures-of-cats.org website. Also a good 60% of people say that the health of a cat breed is very important to them (based on another poll on the website - see cat health problems). Is there a particular reason why this breed should have the longest list of genetic diseases? Another cat breed has a long list, the Persian (see Persian cat health problems) Both are very long standing cat breeds. The Persian is also a very popular cat. I have put the date of origin against the breed to see if there is some correlation.

Perhaps the answer is in their popularity. The more popular a breed the more breeding there will be. The more breeding, the more inbreeding as there is more competition amongst the breeders. The more inbreeding, the more disease...? Not sure.


Update July 2010: A discussion on the prevalence of Feline Infectious Peritonitis (FIP) in cat breeds.
Update August 2010: A discussion on Hip Dysplasia in Cats - this is based on a well researched scientific study

Update Jan 2011: "Elimination of anomalies" is how the authors of Robinson's Genetics for Cat Breeders & Veterinarians (4th ed) call the section on how to eliminate genetic diseases in cat breeds. This is the foremost book on cat genetics in the world.

They say that the anomalies persist despite a desire to remove them. They cite two reasons why this is the case:

1. Complex problem
2. The remedy demands drastic action and the breeders find this unacceptable  - where have we heard that before! Think national debt as one example.

The procedure for eliminating these genetic illnesses depends on the "mode of inheritance" - whether the anomaly displays dominant, recessive mongenic or polygenic heredity.

Sometimes the illness may not be an inherited one. And simply avoiding the breeding of two carriers of a genetic disease does not mean that the disease will be wiped out according to an Abyssinian cat breeder, Gene Rankin, who is quoted in the book at page 92.

However, in theory every genetic disease transmitted by a single dominant gene can be eliminated if "every descendant of every afflicted cat was prevented from breeding" (Robinson's Genetics).

The late onset of some genetic disease present a barrier to this process. One such genetic disease that is late onset is Progressive Retinal Atrophy causing feline blindness. Abyssinians and Bengals can inherit this disease and see list above.

Recessive monogenic heredity presents another problem: detecting the heterozygote or carrier. Test matings can detect the carrier. If the kittens are normal the cat can judged to not be a carrier. Test matings are now considered irresponsible due to advances in testing.

"A major factor in the spread of an anomaly is the relaxation of culling (culling in this context means a cat being removed from the breeding process). Commercial demands on cattery owners are a resistance to culling breeding cats.

There is the constant clash, too, of preserving the breed through inbreeding and outcrossing to eliminate the disease.

The occurence of an anomaly can occur several generations from the "ancestral origin". In the meantime a first class breeding cat that is a carrier has spread the disease far and wide. There is resistance to removing genetic diseases in purebred cats. The major reason in my view is shortsightedness of the cat associations and breeders. They would rather take the easy route and sweep the problems under the carpet.

In the purebred dog world the Kennel Club in the UK have changes the rules, under pressure from the press and sponsors, such that show dogs are to be cleared for good health by veterinarians at the shows before being allowed to win awards. 

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 Genetic Diseases in Purebred Cats the list:-

Abyssinians (date of origin 1860)

• Retinal atrophy
• Psychogenic alopecia
• Patellar luxation
• Renal amyloidosis - this disease is referred to in several books.
• Lysosomal storage disease
• Seems predisposed to feline oral resorptive lesions (lesions on the teeth).

American Shorthair (1966)

• Polycystic kidney disease
• Hypertrophic cardiomyopathy

Bengal (1963)

• Entropion
  (scroll down this linked page)
• Psychogenic alopecia
• Retinal atrophy
• Distal neuropathy (about 10% of cats - source: Fabcats.org)
• Bengal Nose (not confirmed as genetic but seems likely)
• Hypertrophic Cardiomyopathy (HCM)
  

Birman (1919)

• Epibulbar dermoids
• Hip dysplasia

British Shorthair (late 1800s) - read about these on this page: British Shorthair Health.

• Hemophilia B
  
• Neonatal erythrolysis
  

Burmese (early 1900s) - read about Burmese Cat Health covering some of the diseases mentioned below.

• Keratoconjunctivitis sicca
• Erosion of cartilage of third eyelid
• Lethal midfacial malformation
• Ocular dermoids
• Feline Orofacial Pain Syndrome 
• Primary endocaridal fibroelastosis
• Meningoencephalocele
• Hypokalemic myopathy
• Diabetes Mellitus (Sugar Diabetes) may have a genetic propensity (Cat Owner's Home Veterinary Handbook updated edition 2011).

Chartreux (14th century)

• Hip dysplasia
• Patellar luxation

Cornish Rex (1950)

• Hypothyroidism
• Hypotrichosis^2|1

Devon Rex (1960) - see Devon Rex cat breeding for more on this

• Hip dysplasia
• Hypotrichosis
• Spasticity²
• Hypothyroidism
• Patellar luxation ^{1 & 2}
• Spasticity (prevents swallowing)
• Flat Chest Kitten (FCK)
• Abnormal blood clotting
• Muscle weakness - myopathy (autosomal recessive)
• blood type dysfunctionality

Don Sphynx (1987) - also called Donsky

• Reported that the gene that causes hairlessness in this Russian hairless cat (and the Peterbald) can cause ectodermal dysplasia in homozygous form.

Dwarf Cats (first Muchkin 1953) - see dwarf cat health issues

• Pectus Excavatum (funnel chest)
• KCK (Flat Chest Kitten)
• Lordosis

Himalayan (1930-1950)

• Cutaneous asthenia
• Polycystic kidney disease.
• Cataracts
• Psychogenic alopecia

Korat (14th century)

• Gangliosidosis.

Maine Coon (1860s)

• Hip dysplasia ^{1 & 2}
• Hypertrophic cardiomyopathy
• Pectus excavatum
• Patellar luxation

Manx (1730)

• Rectal prolapse
• Corneal dystrophy
• Spina bifida ^{1 | 2}
• Atresia ani
• Constipation
• Fecal incontinence
  

Norwegian Forest Cat

•  Type IV glycogen storage disease (type IV GSD)
•  Hypertrophic cardiomyopathy (possible)

 

Ocicat (1964)

• Pectus Excavatum

Oriental Shorthair

• Hepatic Amyloidosis
  

Persian (1530s) - note the Exotic Shorthair is a shorthaired Persian (American Shorthair and the Persian). These diseases may affect the Exotic Shorthair as well. Certainly PKD does. Visit Persian Cat Health Problems for more on these diseases.

• Mannosidosis ^{1 | 2}
• Seborrhea
• Polycystic kidney disease (PKD)
  
• Chediak-Higashi syndrome ^{1 | 2}
• Congenital ankyloblepharon
• Entropion (scroll down) ^{1 | 2}
• Congenital epiphora
• Primary glaucoma
• Peripheral pseudocysts
• Patellar luxation
• Hip dysplasia 
• Report Daily Mail (UK)16-3--09: male Persians prone to a condition in that causes one or both testicles to remain inside the body, which can result in cancer. I am not sure if this is genetically linked.

Ragdoll (1960s)

• Hypertrophic cardiomyopathy
• Mucopolysaccharidoses

Scottish Fold (1961) - click on this link: Scottish Fold genetic diseases and more.

• Incapacitating joint disease with Scottish Fold to Scottish Fold breeding
• Polycystic kidney disease
• Severe vertebral abnormalities
• Prognathis
• Crippling epiphyseal dysplasia²

Siamese (14th century - traditional and 1960s - Modern). See a full discussion on Siamese Cat Health Problems.

• Asthma
• Mast cell tumors
• Cutaneous asthenia
• Esophageal hypomotility
• Cutaneous mastocytomas
• Hypotrichosis
• Glaucoma,
• Cervical neck lesions
• Hip dysplasia
• Feline hyperesthesia syndrome ^{1 | 2}
• Feline endocrine alopecia
• Adenocarcinomas of the small intestine
• Mucopolysaccharidosis
• Gangliosidosis
• Malignant mammary tumors ^{1 | 2}
• Numerous congenital heart defects (PDA, aortic stenosis, AV valve Malformation, pyloric stenosis, etc)
• Primary endocardial fibroelastosis
• Strabismus
• Nystagmus
• Sphingomyelinosis
• Hydrocephalus
• Chronic Degenerative Keratitis
• Seems predisposed to feline oral resorptive lesions (lesions on the teeth). 
  
• Squint
• Hepatic Amyloidosis
• Congenital heart defects¹
  

Somali (1950s)

• Gingivitis

Sphynx (1966)

• Spasticity ^{1 | 2}
• Alopecia universalis.

Tonkinese (1950s)

• Sensitivity to vaccines - see cat vaccination recommendations
  
• Susceptible to upper respiratory infection - see URIs

Genetic Diseases in Purebred Cats - Source: Medical, Genetic, & Behavioral Aspects of Purebred Cats; Ross D.Clark, DVM.
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This is something I produced before building this page. There is an overlap with the above list, but I have reproduced it verbatim:

Genetically linked diseases

Genetic disorders are Important cat health problems. I have divided this section into two. The first part deals with cat breeds that are breeds due to a genetic mutation and the mutation has accompanying cat health problems. In the second part I deal with "normal" cat breeds that to the best of my knowledge have a propensity to a genetically linked disorder. Breeders always strive to minimize and eventually eliminate these disorders. Both are in summary form with links.

Cat breeds due to genetic mutation

1. Scottish Fold - The genetic mutation that causes the ear pinna (flaps) to fold over also results in an arthritic condition at the joints, tail flexibility and thickness, lack of mobility or hardening of the cartilage. Click here to read about this breed.
2. Dwarf cats - The dwarfism gene that produces short legs can also bring health issues such inward curvature of the spine - the spine drops down around the shoulder blades) and pectus excavatum (funnel chest - flattened ribcage). Flat chest kitten may be present.
3. Devon Rex - The mutated gene that produces the soft curly coat may bring abnormal blood clotting and muscle weakness. Read more. The "Rex" gene also produces a curly coat in the other Rex cats (Selkirk and Cornish) and the LaPerm. I don't know if the same problem affects these breeds.
4. Manx - constipation and fecal incontinence due to the deformities of the spine.

"Normal" cat breeds

1. Persian - This breed has a number of health problems some of which are genetically based, such as (a) Polycystic Kidney Disease (PKD). Click here for all the problems and PKD information (b) Progressive retinal atrophy (PRA) affects Persians (click this link to read about PRA and Bengal cats). It is an early onset type for Persians (c) Eyelid rolled inwards (d) Chronic Degenerative Keratitis, causes a clouded eye and black or brown spot on the cornea (sequestrum).
2. Himalayans and Exotic Shorthair cats are bred from the Persian so these two breeds will have the same health issues at least potentialy.
3. Himalayans may suffer from cataracts due to a single genetic defect.
   
4. All breeds, Maine Coon and Bengal - Heart disease hypertrophic cardiomyopathy (HCM). Read about this in reference to the Maine Coon and Bengal.
5. Maine Coon - Polycystic Kidney Disease (PKD) and Hip Dysplasia and other disease (see Maine Coon cat health for details).
6. Bengal - Progressive retinal atrophy (PRA) - mid-onset (more).
7. Abyssinian - Progressive retinal atrophy (PRA) - late-onset
8. Somali - Progressive retinal atrophy (PRA)
9. Siamese - Chronic Degenerative Keratitis, causes a clouded eye and black or brown spot on the cornea (sequestrum). See Siamese cat health problems for a full discussion on health including genetically linked diseases.