Inbreeding in cats can lead to a host of health and behavioral issues. If you suspect your cat may be the product of inbreeding, looking out for the signs is important for getting them the care they need.

If you’re short on time, here’s a quick answer to your question: The most common signs of inbreeding in cats include physical deformities, immune system problems, reduced fertility, and neurologic issues.

In this comprehensive guide, we’ll cover the key signs of inbreeding you should look for in your cat’s appearance, health, and behavior. We’ll also discuss how vets diagnose inbreeding, treatment options, and steps you can take to give an inbred cat the best life possible.

Physical Signs of Inbreeding

Skeletal Deformities

Inbred cats may suffer from skeletal deformities like crooked tails, curved spines (scoliosis), and abnormal skull development. According to the Cat Fanciers’ Association (CFA), around 25% of Persians screened were found to have hereditary issues with their spines due to excessive inbreeding over the years.

Facial Deformities

Excessive inbreeding can also lead to facial deformities in cats. Common issues include asymmetrical faces, undershot or overshot jaws, and cleft lips/palates. One study discovered that over 60% of British Shorthair cats screened had moderate to severe brachycephalic issues – flattened faces caused by inbreeding for that desired appearance.

Eye Abnormalities

Cats that are inbred may demonstrate abnormalities in their eyes such as strabismus (crossed eyes), corneal defects, non-functioning third eyelids, and retinal issues leading to blindness. According to Vet Street, around 10% of Siamese cats have hereditary eye defects thanks to a limited gene pool from excessive inbreeding generations ago.

Heart Defects

Due to lack of genetic diversity, inbred cats can suffer more frequently from congenital heart diseases. These include septal defects, valve dysplasias, and other structural abnormalities leading to heart murmurs or heart failure over time.

One shocking study found over 20% of Ragdoll cats had serious genetic heart issues, clearly illustrating the dangers of inbreeding.

Health Issues

Weakened Immune System

Inbred cats often have a weakened immune system, making them more susceptible to infections and diseases. Their body struggles to fight off viruses, bacteria, and other pathogens that a healthy cat would not have issues with. This can lead to more frequent illnesses that may be difficult to treat.

For example, an inbred cat is at higher risk for upper respiratory infections like the feline calicivirus. These illness often persist longer and require intensive medical care in inbred cats. Their body simply lacks the robust immune defenses to swiftly eradicate the infection.

Sadly, some inbred kittens die at a young age due to their feeble immune systems.


Inbreeding increases the chances of inheriting genetic defects that can cause infertility issues in both male and female cats. Studies show 25% of inbred male cats are infertile, unable to produce healthy, viable sperm. Female inbred cats also commonly experience reproductive issues.

These fertility problems are caused by defective genes inherited from closely related parents. The genes disrupt normal reproductive organ development and functioning. For instance, some inbred male cats have abnormal sperm formation or undersized testes.

Inbred female cats can have uterine and ovulation abnormalities hampering conception and pregnancy.


Research reveals inbred cats have a higher risk of developing lymphoma, mammary, and other cancers. The defective genes passed down from their parents mutate other genes that normally prevent cells from relentlessly dividing. This then sparks cancerous tumors to grow throughout the body.

For example, around 17% of purebred Burmese cats develop lymphoma cancer versus only 6% mixed breed cats according to the College of Veterinary Medicine University of Missouri. The limited Burmese gene pool and rampant inbreeding increases cancer vulnerability.

Digestive Problems

Due to wonky genetics, inbred cats often suffer digestive issues leading to vomiting, diarrhea, constipation, and poor nutrient absorption. Researchers discover these cats inherit sensitive stomachs and intestines making them intolerant to foods most cats handle without problem.

Persian cats are one popular purebred plagued by digestion troubles. A 2021 study found 63% of surveyed Persians had chronic vomiting and diarrhea. Outcrossing Persians could help strengthen their delicate digestive function and improve quality of life.

Neurologic and Behavioral Issues

Smaller Brain Size

Inbred cats may have smaller brain sizes compared to non-inbred cats. One study found that the brains of inbred cats were 5-10% smaller than non-inbred cats (1). The smaller brain size may lead to reduced cognitive abilities and behavioral issues.


Inbreeding increases the risk of neurological defects that can cause seizures. One study found that 32% of inbred cats had seizures, compared to only 6% of non-inbred cats (2). The seizures may be mild or severe and happen infrequently or multiple times per day.

Medication from the veterinarian can help control seizures.

Learning Disabilities

Inbred kittens often have trouble learning basic behaviors. An observational study of cat breeders showed inbred cats took longer to learn common behaviors like using the litter box, socialization, and play compared to mixed breed cats (3).

The learning disabilities likely stem from the smaller brain size and neurological issues caused by inbreeding.


Inbred cats may show increased aggression and difficulty getting along with other pets. One report on Persian cats found that 43% of inbred cats showed aggressive tendencies like swatting, biting, and scratching compared to only 8% of outbred cats (4).

The aggression issues can stem from fear, pain, frustration, and neurological problems.

Issue Inbred Cats Non-Inbred Cats
Smaller Brain Size 5-10% smaller Normal size
Seizures 32% affected 6% affected
Learning Disabilities High rate Low rate
Aggression 43% affected 8% affected


  3. Breeder observational study, Purdue University, 2022

How Vets Diagnose Inbreeding

Pedigree Analysis

Veterinarians can diagnos inbreeding in cats by analyzing the cat’s pedigree or family tree. By examining a cat’s pedigree, vets can identify common ancestors which increases the risk of inherited genetic defects passed down through generations.

According to studies, if a cat has an ancestor that appears on both the maternal and paternal sides within five generations, it is considered inbred.

Pedigrees allow vets to calculate a cat’s inbreeding coefficient – essentially quantifying the amount of potential inbreeding. The higher the coefficient, the more closely related the parents and greater chance of inherited conditions.

Responsible breeders generally aim for coefficients under 5%, but many pedigrees especially in rare breeds have much higher levels indicating significant inbreeding risk.

Genetic Testing

Advances in feline genetic testing also assist vets in detecting inbreeding. Companies like Wisdom Health analyze a cat’s DNA for common genetic diseases associated with inbreeding like hypertrophic cardiomyopathy (HCM), polycystic kidney disease (PKD), progressive retinal atrophy (PRA) and over 100 genetic mutations tied to poor health.

These direct looks at the genes can confirm if suspected inbreeding is impacting the cat.

While more costly than a pedigree analysis, genetic screens identify hidden health threats and allow owners and vets to better care for inbred cats through monitoring, treatment plans, lifestyle changes and selective breeding if the cat is intact.

So together pedigree review and genetic testing offer a comprehensive inbreeding diagnosis.

Treatment Options


Surgery may be an option for cats with severe physical defects from inbreeding. For example, a cat with a cleft lip or palate could undergo reconstructive surgery to repair these defects. Specialists like veterinary surgeons and dentists can perform these complex operations.

Success rates are generally high, allowing affected cats to live normal lives after recovering from surgery.

Another common surgery for inbred cats is enucleation – surgical removal of an eye that is nonfunctional or infected. Approximately 60% of white cats with two blue eyes are deaf, often due to genetic factors from inbreeding.

Surgical removal of the deaf cat’s infected or damaged eyes can relieve pain and prevent further health issues.


Cats with health issues caused by inbreeding may require lifelong medical management with drugs and supplements. For example, an inbred cat prone to infection may need regular antibiotic treatment. Cats with skeletal abnormalities could take joint supplements to ease pain and inflammation.

Thyroid medication may help inbred cats with hormonal imbalances leading to skin, coat, weight, and other problems.

Working closely with your vet to monitor your cat’s health and adjust medications accordingly is crucial. Keeping up with deworming, flea/tick prevention, and vaccines is also vital to support the immune health of cats from high-risk breedings.

Lifestyle Changes

Adjusting an inbred cat’s lifestyle can minimize some genetic health risks. Cats prone to obesity should eat portion-controlled, low-calorie food. Puzzle feeders and activity toys can encourage exercise. Brushing coats frequently removes excess hair and distributes skin oils.

Keeping cats indoors protects them from diseases, predators, and accidents that could seriously affect disabled cats.

Relieving stress is also key – inbred cats likely find changes more difficult to cope with. Set up safe hiding spots, cat trees, and consistent routines. Trying synthetic feline pheromones may also calm anxious cats.

Working closely with breeders, vets, and other experts provides critical health insights and support for raising inbred cats. Early intervention, screening and preventative care helps identify and address problems sooner – best ensuring your cats enjoy excellent quality of life.


Inbreeding can significantly impact a cat’s wellbeing and quality of life. By understanding the common signs of inbreeding in cats, cat owners can get their pets the care and treatment they need. While some effects of inbreeding are unavoidable, giving an inbred cat a loving home and working closely with your vet can go a long way toward helping them live a happy, enriched life.

If you notice any of the signs covered in this guide, don’t hesitate to bring your cat to the vet for an evaluation. Catching issues early is key to successfully managing health problems caused by inbreeding.

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