Hereditary diseases:
What is Pra-B?
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With Pra, the retina disappears; the blood vessels that feed the retina and remove waste products become thinner and their number decreases and the rods and cones disappear. The cat starts to see worse (night blind) and eventually becomes completely blind. At the end of the disease, all photoreceptors (rods and cones) with which humans and animals can see have disappeared and the pigment epithelium (gives eye color) is also affected.
There is nothing (yet) to do against the disease. Pra only becomes visible at a later age. It is a hereditary disease.
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Symptoms:
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The symptoms associated with Pra are: enlarged pupil, Unwanted rhythmic rapid eye movements, hyperreflexion of the tapetum lucidum (the light reflective layer of cells directly behind or sometimes in the retina that allows the eye to see better in the dark), progressive reduction of the retinal blood vessels and degeneration of the rods and cones.
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Inheritance:
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From Pra we know there is an autosomal recessive form (rdg) and an autosomal dominant form (Rdy). In most cats, the autosomal recessive variant occurs. The frequency of occurrence is low. The recessive form is often discovered late, usually long after the sufferers have already produced offspring.
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From the first bloodlines of the Bengal, a variant of Pra specific to the breed was found. By examining many Bengalis suffering from a form of blindness, which had a negative result on the 'normal' pra-test, they came to the conclusion that they were dealing with a variant of Pra. Possibly this variant could be found within the wild (ALC) line of the first Bengal cats.
Based on this knowledge, laboratories have started working with the DNA material of Bengals suffering from blindness and have been able to develop a test for it which specifically works for the Bengal Breed.
This is the Pra-B test. This also means that only the Pra-B test is usable for Bengal cats and the normal Pra test for cats has no value for this breed.
What is PKdef?
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PK stands for Pyruvate Kinase. This is an enzyme that plays an important role in energy metabolism. Def stands for Deficiency. With PKdef there is therefore a shortage of this enzyme. This in turn leads to a shortage of energy in, among other things, the red blood cells. As a result, those red blood cells no longer function properly and die prematurely. As a result, anemia. The cat then gets, among other things, pale mucous membranes.
Anemia due to an accelerated and increased breakdown of red blood cells is called a hemolytic anemia.
PKdef symptoms:
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The symptoms associated with PKdef are those of hemolytic anemia: lethargy, tiredness, lack of appetite, pale and sometimes yellowish mucous membranes. The urine can be darker in color and often the spleen is also enlarged. Usually, the phenomena are rather vague and vary over time. Does this mean that a PKdef sufferer always faces a short life?
No, it doesn't have to be that way. Cats that suffer from PKdef can still grow quite old. The oldest cat in which PKdef has been diagnosed was 14 years old. But the course of the disease can also be disappointing and then the outlook is less rosy.
PKdef is not curable. Only the symptoms can be treated. Sooner or later, the consequences of PKdef will become noticeable among the sufferers. The severity cannot be predicted and neither can the age at which this happens.
Bengal and PKdef:
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The Bengal is a breed with a relatively narrow gene base. That is why it is not always wise to immediately exclude all Bengalis who are PKdef sufferers or carriers. That would mean that you also lose the good and important genes, while they must be preserved for the quality of the breed. Direct exclusion of PKdef sufferers for breeding irrevocably means that inbreeding problems and other hereditary diseases will arise.
A precise breeding policy is the solution. With well-considered combinations, prevent and exclude the spread of PKdef within the breed and the lines. That's possible! And only then will as much of the diversity in the breed's gene pool as possible be preserved.
Testing on PKdef:
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A cat can be tested for PKdef at a very young age. This is done with a one-off DNA test. This test gives three possible results:
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The cat is "free" and has two "healthy" alleles. The cat will not develop symptoms of PKdef and will not be able to pass on the abnormality to the next generation.
The cat is "carrier" and has one "healthy" allele and one "defective" allele. The cat will not get any symptoms of PKdef, but will pass on the mutant allele to half of his or her offspring.
The cat is "sufferer" and thus has two defective alleles. Sooner or later, the cat will get symptoms of PKdef to a greater or lesser extent. Sufferers pass on the anomalous allele to all their offspring in the next generation.
Breeding with PKdef:
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Never do: carrier x carrier – that results in 25% sufferers.
Never do: carrier x sufferer – that results in 50% sufferers.
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Possibly yes: sufferer x free – that results in 100% carriers – but they do not get sick.
Possibly yes: carrier x free – that results in 50% carriers and 50% free.
The carriers do not get sick and with the healthy animals the line can be continued again without risk. In this way, the gene pool is kept as wide as possible and the breed remains as healthy as possible. If you want to buy a kitten as a pet, then it does not hurt if this kitten is a PKdef carrier.
What is PKD?
It is the abbreviation of Polycystic Kidney Disease, a hereditary disorder in cats.
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PKD is not curable: sooner or later the cat dies of kidney failure.
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PKD is dominant hereditary
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PKD can be determined with tests at an early stage (from 6 months)
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What is it:
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Cats with PKD have multiple fluid-filled cavities called cysts in both kidneys.The older the cat gets, the more cysts will develop and the larger the cysts will become. These cysts suppress the healthy kidney tissue, causing kidney function to decrease. Eventually, chronic kidney failure will occur. Real complaints usually only arise at a later age: around 6 to 7 years the cat gets complaints that will indicate kidney problems.
Why test for PKD:
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Testing for PKD is necessary, because PKD-positive cats simply should not be bred. PKD can be detected at an early stage by means of an ultrasound and so you can exclude these animals from breeding. When breeding with a PKD sufferer, this cat may have conceived several generations before the disease manifests itself! This is therefore not necessary at all, because with the help of an ultrasound by a specialized veterinarian, the diagnosis can be made at an early stage.
What are the symptoms:
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As long as the kidneys are still functioning sufficiently, there will be no complaints. Once more than 70% of the kidney tissue is affected, the cat will develop symptoms of kidney failure: decreased appetite, slimming, drinking a lot and urinating a lot, less active, with abdominal palpation the veterinarian may feel large lumpy kidneys, dehydration (the skin remains standing when you lift it), pale mucous membranes due to anemia, vomiting, bad breath, diarrhea, lethargy and weakness, poor coat care and a bad fur. However, it can take years for these symptoms to become visible.
In order to support the kidneys as much as possible, chronic kidney failure can be 'treated' by means of medication and a special kidney diet. This relieves the kidneys and slows down the process. It is possible to have a cat admitted to rinse the kidneys with the help of an infusion: a kind of dialysis.
What is HCM?
HCM is a hereditary disorder of the heart, in which the muscles of the left ventricle slowly become thicker and therefore stiffer. This does not allow the heart to fill properly with blood. In addition, the space in the left ventricle becomes smaller and smaller, which, among other things, gives a high risk of thrombosis. Because the pressure in the left atrium rises, fluid accumulation can take place in the lungs and chest. This in turn gives a greater pressure in the blood vessels.
All this results in a shorter service life. Males often show a worse form of the disease than females. HCM is one of the most common hereditary heart diseases that can occur in various cat breeds, including bengal.
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In short:
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- HCM cannot be cured, but can be slowed down
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HCM is autosomal dominant
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HCM is hard to detect in an early stage
HCM is not curable, that means that sooner or later the cat will die from it. The disease can be visible around six months, but usually the cat will be 2 to 3 years old. At three to five years of age, the disease often becomes severe.
Possible symptoms:
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An increasing tightness due to fluid in the chest cavity, sudden paralysis symptoms on one of the front legs or on both hind legs due to a clot in the large blood vessels or a sudden death due to clots in the brain.
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Treatment:
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HCM can be slowed down with medications.
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With HCM, the heart walls become thicker and thicker. This causes the heart to enter a downward spiral. Because a thicker heart has to work harder to pump enough oxygen around the body, the heart muscle grows (like any muscle grows with extra training). This aggravates the situation, because the heart walls then become thicker due to the HCM and thicker due to overtraining. There is a drug called Atenolol that forces the heart to work a little less hard. As a result, the thickening of the heart muscle will decrease slightly, making the cat feel comfortable again and extending its lifespan. Note: Atenolol is only prescribed to cats with HCM if the heart rate at home and at rest is really too high, or if there are life-threatening cardiac arrhythmias. Studies have shown that giving Atenolol to clinically healthy cats with HCM makes no sense.
Diagnosis:
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HCM is hard to detect in an early stage. That is very important to know! It is difficult to diagnose HCM, especially in the early stages of the disease. HCM often only reveals itself later in life. This means that a cat cannot show any signs of the disease for years, while the animal does have HCM. You can imagine that when bred with this cat, a large part of the offspring also has HCM. These offspring, in turn, can also spread the disease further if they have also been sold as breeding animals. Add to that the fact that HCM is dominantly hereditary and you immediately understand why this disease is a major threat to the breed.
A good, serious breeder, who gives the health of his animals the highest priority, will have his Bengals tested for HCM periodically (often annually) at all times by means of an ultrasound. These studies are costly and are only a snapshot. Each time the cat is declared 'provisionally free'. It is therefore true that, despite the fact that a female or male has been declared HCM-free for the time being, there is still no certainty about this. But beware: it is the only thing breeders can do to give buyers of kittens some form of certainty about the health of their cat.
HCM-free lines do NOT exist!
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It would be best that cats from pedigree lines in which HCM is clearly found (the so-called high-risk lines) would not be bred. However, the disease is now so intertwined in the breed that that would be quite a challenge. HCM-free lines do not exist!
Because the Bengal is a relatively new cat breed, the exclusion of these lines also creates other problems because the gene pool is reduced (higher inbreeding percentages).
Even if lines have been tested HCM negative for several generations and the breeder always periodically tests the parents for HCM and both of which are negative, a kitten can suddenly be born with HCM.