Polycystic Kidney Disease/ PKD in Savannah Cats

​I’m here with some advice and some very frustrating, disappointing, sad news.
 
Many of you who know my breeding practices and methods here at Stylisticat, will know that we can be quite ‘over-the-top’ when it comes to screening our cats. IF there even such a thing?
 
Recently, we got the vet out to draw blood from every single cat in the cattery and he took the wild cats away to be blood tested through blood draw and lab test at Glasgow University under sedation. We don’t do snap tests because they are so unreliable if it is something that could affect your entire cattery. Gladly for us and £5,000 later, we were able to confirm that every single cat tested negative for FeL-V and FIV. We were also pleased to announce that he condition scored every single cat a 5, except 1 over active stud who was a 4. The scale runs 1 is emaciated and 10 is obese. You want all cats to be a 4 or 5. We were very pleased!
 
We re-worked our 85-page health plan for the cattery and decided a number of ways we would do things going forward to keep our ‘cat colony’ squeaky clean and protected from anything incoming.  I am not sure if you are aware but after explaining our methods to a few breeders, they weren’t aware of a few things. IF you use disinfectant in a litter tray, place litter in it and use a faecal sample from this tray and you A: take the faeces the minute they are out to the vet your sample will only be around 50% actively showing bacteria if sent away, B: take the faeces to the vet in the morning, 25% effective and C: take refrigerated sample to the vet 50% effective. IF you touch the sample with anything other than a completely sterile object, it can fragment the DNA which any PCR test will collect. In layman’s terms, depending on how quickly your sample is transported, what temperature it is stored at and what it came into contact with before it went for sampling will really determine your results.
 
Most samples are only 45% accurate at getting a reading from any sample. That’s less than 50%. This is from Glasgow University’s figures on result sensitivity – our version of UC Davis. A PCR may be 99% accurate at finding any problems but the problem needs to be there to find, and not fragmented or destroyed through coming into contact with anything else, such as disinfectant and being at the right temperature until the point of test. It is 99% accurate at finding a foreign DNA in a 50% diseased sample, so 49% accurate in reality. More than half of your PCR faecal samples are false negatives.
 
The best way to get an accurate reading is to do what is called a faecal flush. This is where the cat is sedated (which you could do your routine bloods at) and 20mls of fluid is squirted into the colon through the rectum and then drawn out. This is repeated several times to really flush any colonic pockets and coax any parasites out that could be deep in the colonic wall. This is 85% accurate at finding ANYTHING faecal PCR’s would normally check for. It is recommended that you do this at least twice over a 4 weeks period to check, three times would be considered rigorous testing and most ideal. We have checked this with a few of our incoming cats and found this to be a very accurate description on the difference between the PCR which would be negative and a flush would be positive on the same cat. After treatment, two further flushes revealed negativity and then admittance to the cattery.
 
Moving on, you will remember a few years ago when I announced that Progressive Retinal Atrophy (PRA) and PRA-Bengal (PRA-b) was a potential issue in the Savannah breed - Link here: https://www.stylisticat.com/blog/archives/01-2017 or progressive-retinal-atrophy-pra-in-savannah-cats.html. Thanks to many of you who began to test all your cats, we were able to discover that it is just as much an issue as Pyruvate Kinase Deficiency, also known as PK Def. Thank you so much to all of you who test – it is so important in producing healthy kittens and it is our responsibility!
 
I am really saddened to be back here again after so many years on working on eradicating PRA and PK Def from lines that I have been working so hard on. We’ve only ever produced from one affected boy, which was the boy we discovered the initial problem with. He has two litters and two carriers were kept back. He got neutered and finally we worked down through 4 generations later to get an N/N kitten which we could say was definitely a keeper. Now remember, a carrier of PK Def, PRA or PRA-b is just that, a carrier of half the DNA. The kitten remains completely healthy and not affected at all by the genetics. Care MUST be taken not to put 2 carriers together as this would produce unhealthy kittens which were affected by the disease. It saddens me that even now, there are breeders who are not testing for this and some are relying on a test result 4 generations back, with no paperwork to save on test funds. Again, it is your responsibility to ensure that you test what your cats have and when you give a health guarantee, you are not selling your kitten to someone with a death sentence, or to a new/ inexperienced breeder who is not ready to understand the complication of having a number of carriers in a cattery. Can you really trust them? Can you ensure they won’t be tempted to ‘breed them together anyway’ and sell to unsuspecting pet buyers? How would it make you feel if you had control of that prevention? Be actively in control!
 
There have been some new cats come in over the past year from USA, Canada and most recently the UK. The lines behind these cats also include Europe and Russia. Most importantly, the lines have A1 and any other known catteries, which means it is likely that you all have some form of what I have to announce, in your catteries.
 
Polycystic Kidney Disease (PKD or PKD1)
 
This is a whole new ballgame. When I previously noted that the other 3 genetic tests are safe to breed from, provided a carrier was mated to a non-carrier, this would almost seem like a walk in the park if you had found it within your cats back then, because this one is a totally different concept.
 
If your cat tests N/N for PKD1, they are OK
If your cat tests N/P for PKD1, the cat has or will become affected from this disease.
If your cat tests P/P for PKD1, the cat has or will become affected from this disease.
 
Thus, there is no carrier state for this disease. They are either affected, or they are not.
I have shared some test results for you – please also note the blood typing. Most of the breeders I have spoken to about this, are not aware of blood typing. More on that in a separate post.

The technical term is that it's the result of a single, autosomal dominant gene abnormality. This means that every cat with the problem gene will have kidney disease. ALL with PKD, whether carriers or fully +/+ will still pass the genetic defect onto their kittens, when if you mate it with an otherwise healthy and unaffected cat. One copy/ half the DNA/ a carrier will be affected itself.
 
Given that I was planning to put a keeper female produced from 2 x USA cats, to a keeper from a Canada x UK pairing, we are looking at a potential serious issue being prevented – since they were both carriers of PKD!

You're thinking "the breed isn't showing loads of dying cats!" This will typically not show up until 7 years old or later. That's a lot of heartbreak to put someone through, let alone the suffering of the cat. 

Pockets of fluid form inside a cyst which grows over time. These can be detected through a scan when a cat is young, but the best way to find out is through genetic testing.
 
Will you be responsible?
Are you going to continue to breed from cats with PKD?
How are you going to plan to move on with your cattery if you find carrier/affected cats?
Are you going to be a responsible breeder and test every single cat BEFORE you breed from it?
Are you still relying on ‘someone’s word’ that the parents of your cats are normal?
Have you ever seen the actual paperwork showing that your cats are normal?
Do you have this ‘in-hand’?
Can you REALLY provide a health guarantee if you aren’t testing your cats? – The answer to that one is NO.
 
The best thing you can ever do is test your own cats. Always.
 
I know this is going to be absolutely devastating for some catteries because breeding from a carrier of PKD will produce carrier kittens that are also affected, so these cats need to be completely removed from the gene pool. You are going to have to take the responsibility on preventing this becoming a major problem in the breed such as the Persians where it’s as high as 38% have this disease.
 
We don’t know where it’s come in to the Savannah breed, like other genetics. But let’s all work together to get it out of this breed!

Let's take a look at this cat:

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NR = Not requested. I already had the parents test papers, so I knew the cat was normal.
PRA and PRA-b are also normal.

I could've happily gone on to breed this cat with another cat who had the same results. Note the 'Add-On Options' at the bottom. The cat is a carrier for PKD. This cat will need to be neutered and petted out. 

Interestingly, this cat also carries one copy of the longhair gene, which we are also trying to eradicate from the breed, so it would be ideal not to breed 2 carriers of longhair gene together and try to keep back those who were N/N. I know in the scale of priority, this is relatively low, but if you are really pushing for that perfect savannah cat to breed from it would be negative across the board for everything such as this girl below. Now I just need to work on getting my agouti to A/A on this girls litter (at my own preference as the solid hair is not a health risk and also an accepted standard within the breed) and I'll have a completely solid line tested to carry forward, with exception to an HCM scan. 

​We just have to keep trying, harder. Push forward with the breeds development, even when faced with problems with the registry and genetics. The harder we work together, the more solid and healthy the breed will be on a united front!

- Kayleigh M-L @ Stylisticat