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The Munchkin cat has recently become an internet sensation, with our timelines filled with pictures and videos of these cute-faced, doe-eyed, stubby-legged cats, which has piqued the interest of many as to why the Munchkin cat looks the way it does. However, along with the cuteness overload, there is controversy surrounding this breed.
The Munchkin cat’s short leg length is caused by a genetic mutation causing chondrodysplasia (sometimes called achondroplasia) which causes abnormal growth plates in long bones leading to stunted growth of long bones (primarily the bones of the front and back legs).
The shortness of the limbs in the Munchkin cat is caused by an autosomal dominant dwarfism gene locus on chromosome B1. This mutation causes heritable chondrodysplasia, which produces disproportionate dwarfism – short, stubby legs and relatively standard body length and head, although this is not always the case.
What Is Chondrodysplasia?
Chondrodysplasia is the medical umbrella term used to describe abnormalities of the cartilage. It is a heritable skeletal bone disorder characterized by dwarfism and abnormal body proportions, such as the short legs seen in the Munchkin cat breed.
Chondrocytes are the cells that make up cartilage and are also the precursors of bone development. In the growing animal, there are areas of cartilage near the ends of the long bones called epiphyseal growth plates, where the length of the bone is determined. The process by which bone is formed from the cartilage is called endochondral ossification and comprises five stages:
- Mesenchymal cells become chondrocytes
- Chondrocytes are compacted at the growth plate
- Cartilage takes the form of the future bone, and blood vessels start to penetrate
- Chondrocytes grow and become able to mineralize
- Chondrocytes are replaced by bone cells (osteophytes)
Bone will continue to grow for as long as the chondrocytes are produced at the growing animal’s epiphyseal growth plate. In animals afflicted with chondrodysplasia, the growth plates often show an inconsistent pattern, thus causing abnormal endochondral ossification resulting in short limbs.
This also explains why leg length will vary among cats in the breed. The following categories of front leg length have been accepted by Munchkin breeders:
- Standard: leg length of 3-4 inches
- Super Short: leg length of 2-3 inches
- Rug Hugger: leg length less than 2 inches
How Did The Munchkin Breed Come About?
Cats with shorter legs occurred naturally and have been periodically observed in nature from as far back as the 1930s. However, the short leg characteristic in cats came to light more so in the 1980s when a music teacher named Sandra Hochenedel from Louisiana, USA, rescued a pregnant cat with short legs due to a spontaneous genetic mutation.
The cat gave birth to a litter, with half of the kittens having limbs of a standard length and the other half with abnormally shorter limbs. Sandra then crossbred one of the males from the litter with the shorter legs with the mother, resulting in half of the litter having short legs.
With the subsequent breeding of these short-legged cats, it is believed that the Munchkin breed descended from this experimental litter and became recognized as an official breed in September of 1994 by The International Cat Association.
Is It Ethical To Breed Munchkin Cats?
The gene that causes short legs in the Munchkin cat is lethal in homozygotes – that is, when the cat possesses two copies of the gene, it will not survive and die before being born (commonly in the earlier stages of embryonal development and the embryo will then be resorbed by the dam). For this reason, the ethicality of breeding the Munchkin cats has come into question, along with the implications of these cats having a skeletal abnormality.
Cats are naturally very agile and activities like running, jumping, and climbing makes up part of their everyday lives. Cats are also very communicative and use various body postures and tail movements to relay their feelings in social interactions with each other and humans. Selective breeding for exaggerated bodily structures, such as the shortened legs in the Munchkin cat coupled with a long spine, limit the ability of the animal to change its body posture to communicate effectively.
In addition to limitations brought on by the abnormal bodily structures of the animal, the changes in the morphology can also cause numerous health risks.
Health Conditions Associated With Chondrodysplasia in Munchkins
A degenerative disease causes tissues – cartilage and bones – in the joints to break down. It can cause severe pain, and owners should take note of signs of pain and discomfort, for example, decreased activity and changes in the way the cat walks.
This condition causes a convex curvature of the spine in the lower back due to the spinal muscles being too short.
3. Pectus excavatum
This is a congenital condition caused by the abnormal growth of the cartilage that connects the sternum and the ribs. The prognosis of the condition is good if diagnosed early. Corrective surgery between eight to twelve weeks is recommended.
Although these conditions are not limited to the Munchkin breed, they are more susceptible to these ailments due to the conformation of their bodies. For these reasons, the Munchkin cat is not recognized as an official breed by the Cat Fanciers Association (CFA) and the American Cat Fanciers Association (ACFA).
What Can I Do To Improve The Quality Of Life For My Munchkin Cat?
Cats that cannot express natural behavior or are in chronic pain risk developing depression and exhibiting socially unacceptable behavior. While Munchkin cats are quite fast and agile at ground level, jumping onto higher surfaces is often a challenge due to their short legs.
It is important to note when using toys, such as a play rod, to not dangle the feathers too high off the ground and out of reach for your Munchkin, as not being able to catch the feathers might frustrate your cat. This 4-in-1 cat scratch post with a cat bed and jute rope is a great option for Munchkin cats as it is low enough for a Munchkin to be able to jump onto the bed part and be able to reach the rope toy.
Your Munchkin has to be able to express natural behavior. Providing your cat with toys and structures for enrichment is essential. Cat scratch posts with a perch make for good additions to the home; however, be sure to add steps or a ramp for your Munchkin for easier access. Also, provide steps or a ramp near windows, so your cat can have a look outside as well. An excellent example of both a cat step ladder and scratch post all in one is the Fukumaro Cat Climbing shelf.
Should you observe changes in behavior or signs of pain in your Munchkin, be sure to seek veterinary advice sooner rather than later to ensure the wellbeing of your cat.
Even though we love Munchkin cats for their short legs, it is important to know the health and welfare consequences of chondrodysplasia. Luckily, there are many things that can be done to ensure that your Munchkin is as happy and healthy as can be.
Modifying their environment to better suit them by, for example, providing steps or low-profile litter boxes will help improve their wellbeing.
You might find the following article useful in this regard:
- 8 Reasons Why Munchkin Cats Should be Kept Indoors Only
- How High Can Munchkin Cats Jump? Can They Get Onto Counters?
- Will Munchkin Cats Land On Their Feet When Falling?
- What Type Of Litter Box Do Munchkin Cats Need? The 5 Best Litter Boxes
- Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Osteogenesis: The Development of Bones.
- Finka, L., 2022. Conspecific and Human Sociality in the Domestic Cat: Consideration of Proximal Mechanisms, Human Selection and Implications for Cat Welfare.
- Struck, A., Braun, M., Detering, K., Dziallas, P., Neßler, J., Fehr, M., Metzger, J. and Distl, O., 2020. A structural UGDH variant associated with standard Munchkin cats.
- Lyons, L., Fox, D., Chesney, K., Britt, L., Buckley, R., Coates, J., Gandolfi, B., Grahn, R., Hamilton, M., Middleton, J., Sellers, S., Villani, N. and Pfleuger, S., 2019. Localization of a feline autosomal dominant dwarfism locus: a novel model of chondrodysplasia.
- Gustafsson, K., 2015. Genetics and Phenotypes of Chondrodysplasia (Achondrodysplasia) Across Domestic Animal Species. Diploma. Szent Istvan University.