Munchkin Cats - Why They Shouldn't Be Bred
Why we breed cats
Since humanity started domesticating animals, we started breeding them. The history of humanity is also the history of our "domestic animals". The domestic cat is one of the most recent domesticated species, with some debate about whether they are actually already completely domesticated or not.
This is because the definition of domestic animals is that of those which "breeding, care and reproduction are being totally controlled by humans producing a reproductively isolated population" (source). Well, most cats, especially feral cats, are not being completely looked after by humans and humans don't control their reproduction. This is only true for pedigree pet cats.
Many cats are not domesticated in the strict sense - they can survive and reproduce without human intervention.
No doubt breeding animals has been important for our evolution - cows produced more milk, horses were fit for working cattle, sheep produced better wool, working dogs were more effective. But nowadays, especially with dogs and cats, the breeding has an aesthetic purpose. Even when we know that this brings the animal significant health issues. So why do we keep doing this?
A study developed by Sandøe et al. in 2017 called "Why do people buy dogs with potential welfare problems related to extreme conformation and inherited disease? A representative study of Danish owners of four small dog breeds" investigated the subject in dogs.
There are many dog breeds with severe health problems, but you see them all around you in the media and with rising popularity. This study highlighted that people that owned breeds with significant health problems, such as French Bulldogs, were not motivated by health when choosing their animal. Instead, they focused on their looks and personality. It's important to note that, even when the owners are made aware of the health problems, this might still not deter them from obtaining a dog belonging to that breed. More than that, when they owned an animal that had a significant health problem, this would not stop them from getting another pet from that breed! Why? It seems that these owners create a strong emotional attachment with their pets, possibly because they require more care due to their fragile health.
What is this study saying? It's saying that it's human emotions that lead us to breed animals with compromised health, sometimes innate and subconscious emotions. It is, therefore, important that all of us concerned about animal welfare think thoroughly about the implications of breeding animals with known health issues - especially considering how many healthy pet animals are euthanased worldwide.
The other dark reason why so many pedigree animals show up is plain and simple - famous breeds cost money, so if you breed them you make money.
Do you own a cat?
What cat breed do you have
The Munchkin Cat
The Munchkin cat was recognised as a breed in 1995 by The International Cat Association. This brought up quite a lot of controversy even at that time due to concerns raised about their mobility.
Munchkin cats are cats with short legs and a long spine. They have this shape due to a genetic mutation. The mutation is autosomal dominant and the gene is also homozyguous lethal. This means that one embryo with one mutated allele will be a Munchkin, one embryo with none will be a normal cat and one embryo with two mutated alleles will die before being born.
What a Munchkin cat looks like
Genetics and Health
Genetically speaking, a Munchkin is a cat with a genetic deffect. This deffect was initially considered as dwarfism, but this is caused by achondroplasia and is accompanied by an overly large head. The Munchkin doesn't possess the large head, and therefore the appearance of the breed is now defined to be due to hypoachondroplasia or pseudoachodroplasia. The condition is also seen in humans, who have short limbs.
So going back to the gene, in humans one of the mutations leading to pseudoachondroplasia occurs in the proximal tyrosine kinase domain of the fibroblast growth receptor gene 3 (FGFR3). However, this has not been determined yet for the Munchkin breed, although the University of Missouri is currently working on a research project on the subject.
It is known, however, how the trait is passed. Each cat has two alleles (copy of one gene) for each gene, one coming from the mother and one coming from the father. In Munchkin cats, one of the alleles has the mutation, let's call it mutation M. One cat with the M allele will be a Munchkin. The healthy allele is the m allele. So this means that all non-Munchkin cats have two m alleles. The genetics of the cat population for the "Munchkin" gene is the following:
- A cat with the alleles Mm is a Munchkin
- A cat with the alleles mm is not a Munchkin
- A cat with the alleles MM is not viable and will be aborted as an embryo
So we see the first problem now - that when a kitten is unluky and has two deffective copies of the Munchkin gene, the kitten will die before being born. What happens when two two Munchkin cats are crossed then?
Crossing two Munchkin
By crossing two Munchkins, which is the way to continue to breed more Munchkins, we can see by looking at the table and knowing what MM, Mm and mm genetics look like that:
- 50% of the offspring will have the mutation that makes the cats be of the Munchkin breed (the two Mm squares)
- 25% of the offspring won't have short legs, so won't be a Munchkin (the mm square)
- 25% of the offspring will suffer spontaneous abortion in the uterus and will not survive (the MM square)
The genetics of Munchkin Cats
Other Health Problems
The genetic disease Progressive Retinal Atrophy (PRE) has been identified in several pedigree breeds, including the Munchkin (source). PRE is a group of genetic disorders that affects the cells in the retina, responsible for eyesight. This results in impaired eyesight and can lead to blindness. It can present as a dysplasia (the cells aren't formed properly and don't work), which has not been identified in the Munchkin so far (only Abyssinians and Somalis). It can also present as degeneration (the cells die off) which is progressive and can start around 1.5-2 years of age, resulting in blindness 3-4 years after. This has been identified in the Munchkin as being caused by a mutation the gene CEP290 (source). There is, however, a genetic test available for this disease which is autosomal recessive (to have the disease, the cat must have two deffective alleles, not just one).
PRE is the only genetic disease for which there is confirmed scientific evidence in the Munchkin breed. When the breed was recognised, several animals reportedly had radiographs of the spine taken and were seen to be normal. However, it's not hard to find current radiographs of Munchkin cats with joint disease due to their comformation and they are thought to be at higher risk for osteoarthritis. Although no numbers are published, it's reported that the incidence of lordosis and pectus excavatum is higher in Munchkin breeds when compared to others (source, source). Lordosis is the bending of the spine to one side. Pectus excavatum or "concave chest" is a rare condition in which the sternum (the chest bone) is not properly formed and reduces the size of the chest cavity. Some authors reckon that the abnormal shape of the Munchkin cats can be painful and debilitating due to abnormal joint formation (source).
It is also thought that, because of their shape, Munchkin cats are not able to move and jump like other cats, which may ultimately have an impact on their behaviour. On top of that, they are probably also unable to groom themselves to the same extent of other cats, so will need extra care from the owner.
Munchkin Cats are thought to be less flexible
They are still loving cats
Despite all of this, the Munchkin is a cat just as lovely as any other cat. They are said to be friendly, playful, people-oriented and intelligent. As we've seen, we're often attracted to their physical characteristics in an innate and subconscious way and we get attached to them.
It is, however, our responsibility to them and all the other cats to prevent suffering. The International Cat Society defends that when it comes to breeding cats, no harm should be done. If the Munchkin can suffer with joint pain and spine deformities because we breed them like that, it's our duty as cat lovers to prevent this. This is the ultimate proof of love for cats. And don't get us wrong. We know - and one of the studies referenced by us suggests this - that Munckin owners love their pets and have a strong emotional attachment to them. But for every expensive Munchkin that potentially has a life full of suffering there is a poor abandoned cat in a shelter or in death row waiting for a happy family. Cat lovers love every cat, regardless of breed or colour, and we wish to save all of them.
Instead of buying an expensive designer cat, reach out to your local shelter and save a life :)
© 2017 Andreia Dias