Hereditary or genetic diseases do not spare cats any more than humans. Our companions with mustaches are all the more subject to it as men have made selections based on aesthetic criteria, to give birth to “purebred cats”.
Today, successive breeding strategies have existed for more than two centuries and have intertwined purebred cats and alley cats. The entire feline population, with or without a pedigree, is therefore affected by hereditary diseases.
Simple or multifactorial hereditary diseases
Using more scientific terms, two main types of hereditary diseases can be distinguished. On the one hand, monogenic (or simple) diseases determined by a single gene, and on the other, polygenic (or multifactorial) diseases determined by several genes.
The use of genetics makes it possible to classify simple hereditary diseases and even to predict them statistically in a litter of kittens. Multifactorial hereditary diseases, on the other hand, are more difficult to predict and identify.
The most famous hereditary diseases of cats
In this article, we focus on the most well-known hereditary diseases of cats. These are the most frequently encountered monogenic diseases, but also those that can be diagnosed through the use of a DNA test.
Polycystic kidney disease (PKD)
This hereditary disease mainly affects cats of the Persian breed and related (Exotic Shorthair, British Shorthair, etc.). Called PKD in English for Polycystic Kidney Disease, polycystic kidney disease, as its name suggests, is a disease manifested by the progressive appearance of cysts in the kidneys of the affected cat.
The older the cat, or the more it is affected by PKD, the more the cysts multiply and grow, leading to chronic kidney failure. The symptoms that accompany this inherited disease are vomiting, diarrhea, weight loss and listlessness.
The mode of transmission of PKD is autosomal dominant. This means that the kitten with PKD has at least one of its parents carrying the mutated gene (PKD1 gene). There is no treatment to date against the disease and it can appear at any age.
Hypertrophic cardiomyopathy (HCM)
This disease is transmitted in the same way as PKD, via the mutated gene MYBPC3. It mainly affects Maine Coon and Radgoll cats. Called Hypertrophic CardioMyopaty in English, hypertrophic cardiomyopathy results in health problems affecting the heart.
It generally goes unnoticed until the first symptoms appear, including exertion intolerance, heart murmur or even dyspnea. The development of the disease leads to acute heart failure with arrhythmias, pulmonary edema, arterial thrombosis, cardiac arrest and sudden death.
Glycogenosis type IV (GSD-IV)
This is a rare, but unfortunately fatal, genetic disease that only affects the Norwegian cat OR Skogcatt. It is autosomal recessive and is caused by the GBE1 gene. This means that an adult cat can be a healthy carrier and pass it on to his offspring.
The survival rate of the kittens is then low, but some survivors can do well until the age of 6 months maximum. The glycogen is then no longer converted into sugar by the body and invades the kitten’s cells and organs. Muscle atrophy follows, generalized weakness and inevitably death.
The affected cat has a very limited life expectancy, not exceeding one year in most cases.
Neonatal erythrolysis (NI)
It is a common cause of death in kittens as young as a few days old. This disease is, fortunately, preventable if we know how to recognize the first symptoms quickly.
It can affect all cat breeds even if some are more predisposed than others, such as the Abyssinian, the Burmese, the British Shorthaire, the Chartreux, the Persian, the Rex Cornish, the Rex Devon or the Sphynx.
Neonatal erytrhrolysis is caused by the CMAH gene and is due to incompatibility between blood groups. If the female is group B and transmits A antibodies via colostrum to her group A kitten, these will destroy the kitten’s red blood cells, which can die in a few hours or a few days.
Symptoms are blood in the urine, jaundice, necrosis of the extremities, and stopping breastfeeding. By isolating the kitten from its mother via another lactating cat or bottle feeding, neonatal erythrolysis is avoided.
Progressive retinal atrophy (PRA)
PRA or progressive retinal atrophy is, as the name suggests, an inherited disease causing progressive degeneration of the retina, up to blindness which usually occurs at the age of 3 or 5 years.
It is an autosomal recessive disease due to the CEP290 gene which affects many cat breeds: Abyssinian, American Curl, American Wirehair, Balinese, Bengal, Cornish Rex, Munchkin, Siamese, Tonkinese, etc.
Although it does not result in the death of the cat, it remains a handicap for this predator and excellent hunter. It is not possible to predict whether a carrier kitten will develop the disease, nor is there any treatment to delay its onset.
Spinal muscular atrophy (SMA)
Known as SMA, spinal muscular atrophy is also an inherited autosomal recessive disease caused by the LIX1 gene. It only affects the Main Coon breed. The first symptoms appear in the kitten from its 3 or 4 months and are identical to those developed by humans for the same disease.
Discreet tremors followed, an abnormal gait visible on the hind limbs, then muscle weakness and sometimes great difficulty in moving. There is no cure.
How to avoid hereditary feline diseases?
Known hereditary diseases are not inevitable. They can be limited or even eradicated thanks to an adequate repopulation program of a breed, without losing the characteristics that make it beautiful.
Limit consanguinity as much as possible
Consanguinity inevitably reduces the richness of the genetic heritage and accelerates the appearance of hereditary diseases. It increases the so-called recessive diseases when they can be controlled.
This involves the use of systematic DNA tests for all individuals of the same breed. It is then advisable to make marriages while avoiding any consanguinity (particularly if it is at risk) to eradicate the known hereditary diseases.
Promote crossbreeding as soon as possible
To increase and diversify the genetic heritage, it is useful to introduce new individuals to promote interbreeding and the health of purebred cats. By promoting marriages with individuals of other similar breeds, or simply mating with healthy alley cats, we give the purebred cat the diversity it needs for good development.
Individuals closest aesthetically to the breed concerned can thus be kept in the line, while the others will be excluded. But the health of all individuals will be improved through this genetic mixing.
Require DNA testing for cats prone to genetic diseases
Well-known genetic diseases affect some breeds more than others. The kittens and adult cats are bought from a kennel which must do all the DNA tests before resale. Certain diseases are also classified as crippling or “hidden defects”.
You can check with the LOOF (Official Book of Feline Origins) before adopting a purebred cat to find out the hereditary diseases to which it is subject and to require the seller to carry out genetic tests before purchase. Otherwise, do not hesitate to consult your veterinarian to have your cat tested as soon as possible.