It is important for breeders to have genetic testing done on their cats. It is important for many reasons including improving the quality, health, well-being, and sustaining the breed as a whole. Luckily, Savannah cat breeders have many tools available for advanced testing of their cats. This ensures the best possible health of the kittens.
Available Tests for Inherited Disease
The following are important genetic tests available.
PK Deficiency (PKdef)
Progressive Retinal Atrophy (PRA) (PRA-rdAc or PRA-b)
Hypertrophic Cardiomyopathy (HCM)
PK Deficiency
PK Deficiency, (PKdef) PKdef is a form of inherited and severe anemia found in cats.
Breeds appropriate for PKdef testing: Abyssinian, Australian Mist, Bengal, Domestic Shorthair and Longhair, Egyptian Mau, La Perm, Maine Coon, Norwegian Forest, Savannah, Siberian, Singapura, Somali, Toyger
How to understand the results in testing for PKdef:
Alleles: (one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.)
N = Normal, K = PK deficiency
Cats with N/N genotype will not have PK deficiency. They cannot transmit this PK deficiency variant to their offspring. (cats with N/N are healthy)
Cats with N/K genotype will not have PK deficiency, but are only carriers. They will transfer the N/K variant to 50% of their offspring. Matings between two carriers are predicted to produce 25% PK deficiency-affected kittens. (cats with N/K are healthy and only a carrier)
Cats with K/K genotype will have PK deficiency; severity of symptoms cannot be predicted and may be variable. They will transmit this PK deficiency variant to all of their offspring. (cats with K/K are unhealthy)
A cat with a N/N genotype bred with a cat with a N/N genotype will have N/N kittens. (kittens in these litters are not required to be tested)
A cat with a N/K genotype bred with a cat with a N/N genotype will have 50% of kittens with N/N genotype and 50% of kittens with N/K genotype. (All kittens in these litters must be tested)
A cat with a N/K genotype bred with a cat with a N/K genotype will have kittens with N/N genotype and N/K genotype carriers and 25% of kittens will be K/K PKDef. (All kittens in these litters must be tested)
A cat with a K/K result should not be bred.
Kittens with a N/K genotype can be sold as breeders to a responsible breeder who does testing on their cats and is aware the kitten has the N/K genotype so they can only breed to a cat with a N/N genotype.
All breeding cats at Luxury Savannahs Cattery are tested and confirmed N/N genotype for PKdef.
Progressive Retinal Atrophy
Progressive retinal atrophy (PRA) is degeneration of the retina, causing progressive vision loss in both eyes with eventual total blindness.
Test to determine genotype is: PRA-CEP290
Breeds appropriate for testing:Abyssinian, American Curl, American Wirehair, Balinese, Bengal, Colorpoint Shorthair, Cornish Rex, Javanese, Munchkin, Ocicat, Oriental Longhair, Oriental Shorthair, Peterbald, Savannah Cat, Siamese, Singapura, Somali, and Tonkinese.
It is important that Savannah Cats are tested for PRA because of the ancestry with the cats that were used by outcrossing with the Serval are many of the breeds listed as appropriate for testing.
How to understand the results in testing for PRA rdAc:
Alleles: (one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.)
N= Normal, rdAc= Progressive Retinal Atrophy (CEP290 mutation-associated)
Cats with N/N genotype do not have CEP290/rdAc Progressive Retinal Atrophy and cannot transmit this Progressive Retinal Atrophy variant to their offspring. (cats with N/N are healthy)
Cats with N/rdAc genotype do not have CEP290/rdAc Progressive Retinal Atrophy, but are carriers. They will transmit this Progressive Retinal Atrophy variant (carrier) to 50% of their offspring. Matings between two carriers are predicted to produce 25% kittens affected by this CEP290/rdAc form of Progressive Retinal Atrophy. (cats with N/rdAc are healthy and only a carrier)
Cats with rdAc/rdAc genotype will have CEP290/rdAc Progressive Retinal Atrophy, an untreatable condition leading to eventual blindness. They will transmit this progressive retinal atrophy variant to all of their offspring. (cats with rdAc/RdAc are unhealthy)
A single nucleotide mutation in the gene called CEP290 produces a defective protein which is associated with PRA in the cat.
A cat with a N/N genotype bred with a cat with a N/N genotype will have N/N kittens. (kittens in these litters are not required to be tested)
A cat with a N/rdAc genotype bred with a cat with a N/N genotype will have 50% of kittens with N/N genotype and 50% of kittens with N/rdAc genotype. (All kittens in these litters must be tested)
A cat with a N/rdAc genotype bred with a cat with a N/rdAc genotype will have kittens with N/N genotype, N/rdAc genotype (carriers), and 25% of kittens will be rdAc/rdAc. (All kittens in these litters must be tested)
A cat with a rdAc/rdAc result should not be bred.
Kittens with a N/rdAc genotype can be sold as breeders to a responsible breeder who does testing on their cats and is aware the kitten has the N/rdAc genotype so they can only breed to a cat with a N/N genotype.
Cats that show rdAc/rdAc have inherited the full disease. Affected cats are born with normal vision, show retinal degeneration at about 7 months and are blind by age 3-5 years. The condition has no treatment.
All breeding cats at Luxury Savannahs Cattery are tested and confirmed N/N genotype for PRA rdAc.
Hypertrophic Cardiomyopathy (HCM)
Hypertrophic Cardiomyopathy (HCM) is a condition that causes the muscular walls of a cat heart to thicken. This decreases the heart’s efficiency and can cause the lungs to fill with fluid. HCM is one of the most commonly encountered heart disease in cats.
> Unfortunately, there is no specific test for the Savannah cat breed yet.
The best possible way to test for HCM is echocardiography.
Some breeders, myself included, use the HCM test for Bengal or Maine Coon cats. This is a test that uses sound waves to create an image of the heart. Cats with HCM, show images of thickened walls and constricted volume of the left ventricle of the heart. This testing is expensive, so it is best to look for HCM clinics often sponsored at TICA cat shows.
A regular vet often does sonograms but does not have the training or do enough of them per year to make accurate measurements of the thicknesses of the walls of the heart to make a accurate diagnosis of HCM normal or affected.
HCM is probably the most difficult issue a Savannah breeder faces as there are just not that many places to get it done.
Some breeders will drive 5+ hours each way and stay overnight to get it done.
Breeds appropriate for testing:
Ragdolls, Maine Coon, oriental breeds (Himalayan, Burmese, Sphynx, Persians) and Devon Rex, but can also be diagnosed in Domestic Shorthairs, Bengals and Savannahs.
In Maine Coons and American Shorthairs, HCM has been confirmed as an autosomal dominant inherited trait. The disease has variable expression; meaning some cats are severely affected, others are only mildly to moderately affected, and *some cats may not have evidence of the disease yet produce affected offspring.
** While a specific feline gene mutation has not yet been identified, research is underway. Very few veterinary cardiologists and geneticists have the expertise to study genes. It is unlikely that the responsible gene or genes for each affected breed will be found at any time in the near future. If a gene is identified as a cause of HCM in one breed of cats, it may not be the same gene responsible for HCM in other breeds. HCM will require investigation in each breed individually.
How is Genetic Testing Done?
For Savannah Genetic testing, it is important to identify Iand correctly collect samples in successful DNA profiling. We recommend that samples be collected by law enforcement personnel, animal control officers, veterinarians, or other experienced professionals.
The PKdef and PRArdAc tests can be done by using the Swabbing Method.
Swabbing Method: Lightly moisten a clean cotton swab with sterile water or saline solution available from a drug store. Carefully rub the inside of the gums between the cat's cheek and teeth with both sides of the cotton swab, collecting as much material as possible. One swab should be handled at a time, but it is best to use at least two swabs to make sure you have enough DNA sample for the lab. Allow the swabs to air-dry while keeping them out of direct sunlight. Never use a hair dryer or anything but the air to dry them. You will usually tape them at the middle of the swab to the paper that you will need tested, and then fold the paper over the swabs and place the paper with the swabs inside an envelope and seal and sign across the seals.
