What Happens When Cats Are Inbred?

Inbreeding in cats refers to the mating of closely related cats, such as between siblings or cousins. This can occur when breeders intentionally breed family members or when unneutered cats mate with their relatives. In the wild, cats generally avoid inbreeding due to the risks it poses. However, domestic cats may inbreed naturally if left unsupervised, especially if few unrelated mates are available.

There are a few key reasons inbreeding happens with cats:

  • To preserve desired physical traits and conform to breed standards. Some breeders specifically breed related cats hoping to solidify certain features.
  • When unneutered male cats mate with their daughters or sisters once they reach sexual maturity. This can occur if cats from the same litter are left unfixed.
  • In stray cat colonies where there are limited mates available, leading cats to breed with siblings or parents.
  • To try to maintain rare coat colors or patterns, like flame point Siamese cats. Breeding relatives is seen as increasing chances of the traits breeding true.
  • Accidental inbreeding can occur if pedigree records are not properly kept, leading to unknowing matings between relations.

Cats do not have an inherent mechanism to avoid inbreeding like wild felines. So human oversight is required to prevent closely related cats from mating.

Health Risks

Inbreeding increases the risk of genetic defects and health problems in cats. When closely related cats are mated, it increases the chances that faulty genes are passed on and expressed (International Cat Care, https://animals.mom.com/problems-with-inbreeding-cats-5105419.html). Some key health risks associated with inbreeding in cats include:

Higher chance of genetic defects – Inbreeding results in homozygosity, where kittens receive two copies of a detrimental gene from each parent. This significantly increases the likelihood of genetic diseases and abnormalities (https://pubmed.ncbi.nlm.nih.gov/36002141/).

Weaker immune system – Inbred cats tend to have a weaker immune system, making them more prone to infections and illnesses. Their body is less able to fight off pathogens and diseases.

Shorter lifespan – Due to increased health problems, inbred cats generally have a shorter lifespan compared to non-inbred cats. Their risk of illness and genetic disorders results in a decreased life expectancy.

Behavioral Issues

Inbreeding in cats can lead to a variety of concerning behavioral problems. According to research by Casal et al. published in the Journal of Feline Medicine and Surgery, inbreeding reaches a certain threshold where it negatively impacts behavior in cats.[1] Some of the most common behavioral issues seen in inbred cats include:

Increased aggression – Inbred cats often show higher levels of aggression towards other cats as well as humans. This is likely linked to developmental issues and genetic abnormalities caused by inbreeding.

Higher anxiety – Inbred cats tend to be more anxious, fearful, and prone to stress. They may be very sensitive to physical contact and exhibit withdrawal or isolation behaviors.

According to research from The Cat Bandit blog, inbred cats can struggle with fearfulness, anxiety, and sensitivity due to genetic issues.[2] These problematic behaviors are very difficult to correct through training alone.

Overall, inbreeding takes a major toll on normal behavioral development in cats. It often leads to increased aggression, fear, anxiety, stress, and other concerning issues that impact quality of life and adoptability.

Physical Abnormalities

Inbreeding can lead to a variety of physical abnormalities in cats. Some common issues include:

Skeletal deformities: Inbred cats may develop skeletal abnormalities like crooked tails, malformed joints, and fused vertebrae. These deformities can lead to osteoarthritis and mobility issues (Problems With Inbreeding Cats).

Organ dysfunction: Inbreeding has been associated with heart defects, kidney problems, and gastrointestinal issues in cats. The weakened immune system of inbred cats also puts them at higher risk for infections affecting major organs (Feline Fertility Consequences of inbreeding and Outbreeding in Pedigree Cats).

Poor development: Inbred kittens often have low birth weights and fail to thrive. They may exhibit delayed motor skills, slow growth, and neurological problems. Surviving kittens can have lifelong impairments due to poor prenatal development (Problems With Inbreeding Cats).


There are several solutions that can help address the issue of cat inbreeding and promote genetic health in feline populations:

Outcrossing programs involve mating unrelated cats from different lines or breeds. This increases genetic diversity and reduces the chances of inheriting two copies of harmful recessive genes. Responsible breeders frequently outcross to maintain health and vigor in their breeding lines. For example, some Siamese breeders have outcrossed with oriental shorthairs.

Adopting cats from shelters and rescue organizations also helps. Many mixed breed cats in shelters have diverse genetic backgrounds due to random mating, so adopting them reduces demand for intentionally bred cats. Shelter cats have a reputation for being healthy and having hybrid vigor.

Finally, supporting responsible cat breeding practices is important. Responsible breeders health test their breeding cats, avoid excessive inbreeding, and work to maintain genetic diversity within their breed. They carefully select pairings to avoid doubling up on health issues and track pedigrees over generations.

For more information, see:

Ethical Concerns

There are serious ethical concerns around deliberately breeding cats from close relatives. Inbreeding increases the chances of genetic diseases and physical abnormalities, which can cause great suffering for affected cats. According to one study, inbred cats are prone to issues like heart defects, immune deficiency, vision and hearing loss (1). Keeping these defective traits in the breed line through continued inbreeding perpetuates animal cruelty.

While some breeders argue that inbreeding is necessary to preserve desired traits, this comes at the expense of the health and wellbeing of individual cats. There are more ethical ways to develop breeds, such as carefully managed outcrossing programs. Ultimately, deliberately creating living beings prone to defects violates principles of animal welfare (2).

(1) https://journals.sagepub.com/doi/full/10.1177/1098612X221118755

(2) https://www.quora.com/Is-inbreeding-cats-good-or-bad

Common Inbred Breeds

Certain cat breeds are more prone to inbreeding due to their popularity and closed breeding pools. Two notable examples are fold-eared breeds and Persian breeds.

Fold-eared breeds like the Scottish Fold cat have a genetic mutation that causes the ears to fold forward and downward. This trait is perpetuated through continued inbreeding, as breeders mate related cats that possess the fold-ear gene. Other fold-eared breeds include the British Shorthair, Highlander, and American Curl.

Persian breeds are also highly inbred to achieve and maintain their distinctive physical features like a flat face and long, luxurious fur. The Persian cat and its relatives, including the Himalayan and Exotic Shorthair, have limited genetic diversity since only certain cats are allowed into the pedigree breeding pool to maintain breed standards. Continued closed breeding results in more homozygosity and the emergence of genetic disorders.

Signs of Inbreeding

There are several signs that may indicate a cat has been inbred. Some of the most common signs of inbreeding in cats include:

Small litter size – Inbred cats often produce smaller litters, sometimes only having 1-2 kittens per litter compared to the average of 4-6. This is according to the article What Are the Signs of an Inbred Cat?

Similar appearance between littermates – Kittens from the same litter may look nearly identical if the parents are closely related. They may have very similar coat patterns and colors, facial features, body types, etc. The article Understanding the Risks of Inbreeding in Cats notes this as a potential sign of inbreeding.

Other signs like physical abnormalities, health issues, and behavioral problems are also more common in inbred cats. Careful breeding practices are needed to avoid inbreeding depression.

Preventing Inbreeding

There are a few key ways to prevent inbreeding in cats:

Genetic testing can be done to screen cats for genetic diseases and disorders. This allows breeders to identify cats that may be carriers for harmful mutations and avoid breeding those cats together. Genetic testing through companies like Veterinary Genetics Laboratory can screen for over 140 genetic mutations in cats.

Careful selection of mates is also important for preventing inbreeding. Breeders should examine pedigrees and avoid mating closely related cats. Outcrossing to unrelated lines can help maintain genetic diversity. Responsible breeders often import cats from other regions or countries to expand the gene pool. AI (artificial insemination) also makes it easier to breed cats across distances.


In conclusion, inbreeding in cats can lead to some serious health and behavioral issues. Inbred cats are at a higher risk for genetic defects and abnormalities such as reproductive issues, weakened immune systems, crooked tails, and cleft palates. Behaviorally, inbred cats may exhibit increased aggression or other abnormal behaviors.

While some purebred cat breeds have a higher incidence of inbreeding due to closed breeding populations, responsible breeders aim to minimize it through careful pedigree analysis and outcrossing programs. Kitten mortality rates are higher when the parents are closely related.

It’s important for prospective pet owners to do their research when acquiring a purebred cat and to choose an ethical breeder who health tests their breeding cats. Signs of inbreeding may not be obvious initially but can show up later in the cat’s life.

Ultimately, minimizing inbreeding helps preserve the health of cat breeds and populations. Breeding decisions should balance preserving desired breed traits with the risks of inbreeding depression. With conscientious breeding practices, cat breeds can thrive for generations to come.

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