I have heard of hip dysplasia,allergies, epilepsy, eye problems from purebred dogs, but I haven’t heard anything about purebred cats.
Several decades ago, white cats with blue eyes were invariably deaf. I’d be interested in hearing if that were still the case.
Not invariably. This has nothing to do ( well, little ) with breeds per se. White cat/blue eyes due to albinism, they are not. As Siamese/Tonkinese and similar asiatic breed coat patterns are a variety of albinism, I believe they generally don’t suffer from deafness even if blue-eyed.
With white cats produced by one of two other genetic reasons ( piebald spotting or “dominant white” genes ) they can be. They can also be deaf without blue eyes. Blue eyes are just very rough indicators.
It has to do with the melanocytes that both produce pigment and are necessary for proper maintanence of the auditory nerve. In albinos the melanocytes are present but melanin production is inhibited enzymatically, so the auditory nerve is unaffected. In non-albino white cats, the melanocytes themselves are actually lacking and this can cause the auditory nerve to break down, causing deafness.
The blue eyes indicate a lack of melanocytes in the region near the ears, hence the rough diagnostic properties. So in odd-eyed white cats with one orange and one blue eye, the orange side obviously has some melanocytes to produce melanin to produce the colored eye - as a result you often have deafness on the blue side, but hearing on the orange side. But it’s never 100% either way.
As far as inbred traits in pure bred cats, yes, you get them ( including hip dysplasia in big-bodied breeds like Maine Coons ). But cats haven’t had near the selective breeding pressure of dogs with their multiplicity of functions, so the deleterious recessives haven’t seemed to crop up quite as frequently.
Certainly Peke-nosed Persians have their share of issues due to the extremely flat face. The aggressive inbreeding that was done to create these cats in quantities when they started becoming popular a couple decades ago made them prone to sinus and eye problems.
Certain diseases such as polycystic kidney disease, amyloidosis (renal disease), hypertrophic cardiomyopathy (heart disease), some types of cancer (mammary tumors?) have been associated with certain breeds (forgot to pair it up, but IIRC, when in doubt the answer is Persian). Other breeds such as Siamese and Maine Coons are prone to some of those diseases, too (or may be THE condition associated with them, as I said, I forgot).
As a Bengal cat owner, I’ve noticed on discussion boards that Bengal cats seem to have more behavioral problems than other cats (although this isn’t an illness per se, just less domsetic for some households). In fact, I got my cat because the previous owner couldn’t deal with his antics anymore (I wasn’t about the buy a pure bred, but as a give away…he’s art in motion…just a bit wilder than most cats, even in old age.)
Siamese cats are susceptible to a certain kind, or kinds, of heart disease. I’m not sure which one or ones.
Siamese are also a breed that has suffered from Popular Sire Syndrome. One individual meezer has contributed a lot to the Siamese gene pool, because of his looks. This cat was Fan Tee Cee, and the judges went wild over his wedge shaped head and very slender body. For a while, the older style appleheads were out of favor, but are making a comeback. Colourpointed Cats - Snowshoe, Tonkinese, Neva Masquerade, Opal, Masked Silver and Cross-Breeds
I don’t think that cats suffer from genetic diseases as much as dogs do, because cats generally find their own mates, if they are left with their sex organs. It’s possible to contain a bitch in heat, but it’s much harder (but still possible) to contain a queen in heat.
There’s an extensive list here.
Be sure to note that both purebred dogs and cats have far fewer genetic problems than your average human…
How do you come to that conclusion? My understanding was that inbreeding caused very serious canine issues like hip dysplasia (golden retrievers & German shepherds), breathing (bulldogs) and spinal issues (dachshunds). Why do you think a non-inbred human would have far more inherent genetic problems than an inbred dog?
Inbreeding doesn’t create anything, it merely makes it more likely that recessive traits will show up. Hip dysplasia is a problem that almost all breeds and mixed breeds have, you just don’t hear much about it in mutts because who goes about xraying “breeding stock” in mixed breeds? Humans can also have hip dysplasia - I was born with it myself.
Breathing issues in Bulldogs and spinal issues in Dachshunds are the result of misguiding breeding for exaggerated breed characteristics by show dog people, who I will not comment on since whe are not in the Pit… Anyway, those things have nothing to do with inbreeding or outcrossing, they are a function of structure.
The thing is, most genetic issues become widespread in a breed not because of whether or not they were inbred or outcrossed, but because the breed became popular and puppy mills started churning them out. Puppy mills don’t generally give a rip about the genetic health of their breeding stock, as long as they can produce pups that will live long enough to be sold to some unsuspecting family, usually for an inflated price. Same thing with mixed breed pups - noone cared enough to make sure that their parents were not dysplasic, going to go blind, had seizures, etc. “Hybrid vigor” is pretty much a lie in dogs, since all breeds and mix breeds are the same species.
As for humans, since it is very rare that people will make, er, breeding decisions based on the health problems the father and mother have, over the centuries we have spread quite a few genetic problems far and wide. Even more so in the last few decades as transcontinental travel has gotten easy. For example, I inherited asthma, RA, severe depression and poor vision from my father and low blood pressure from my mother. My husband is likely to die of cancer since both of his parents did, and he inherited high blood pressure and the tendancy to become addicted from his father. Compare that the the three dogs in my yard, the result of six generations of careful breeding. One inherited a minor dose of a coat problem my breed has, but his hips, eyes and heart are all cleared (he’s neutered). Another passed all health tests including coat and the third has had her heart cleared and has an appt to get her hips and eyes done next weekend. Even if she doesn’t pass radiographically, it is highly unlikely that she will ever actually be affected because her pedigree is chock full of dogs with good hips and eyes.
I don’t think that there are any humans who even know what the health status was of everyone five generations behind them, must less able to say they were all clear!
PETA pushes this “purebred must equal unhealthy” stuff, but since their grasp of genetics is extremely poor (not to mention their grasp of statistics) you would do well to not listen to them (if you have been).
To say that inbreeding doesn’t “create” physical problems but merely increases the probability of their occurrence is a somewhat meaningless distinction re my statement about inbreeding leading to health problems in dogs.
I don’t really think your comparison/contrast of the relative genetic problems of purebred dogs vs humans makes any sense. Line breeding dogs to reinforce specific physical traits often brings serious negative traits along as well. Even if you are not inbreeding your personal dogs to each other, if they are members of a particular breed their genome is usually already somewhat compromised.
See New Study Shows the Problems of Inbreeding Dogs
Re humans not making any genetic fitness distinctions in choosing mates I think you are completely wrong. Human females (and to a lesser extent males) are wired to make fairly sophisticated assessments of physical and mental fitness in choosing mates even if they are not overtly aware of the cognitive mechanics how this selection process is operating in making these assessments.
That is simply incorrect.
Hardly meaningless. If the gene(s) for a physical problem aren’t there, you can inbreed till the cows come home and will never see that problem. For example, two of my dogs are pure for black, in that they don’t carry the gene for the brown color that is also found in my breed. I can inbreed those two all I want and would never see a brown pup.
OTOH if I outcross, particularly in the case of things that are inherited thru more than one gene, I have no real way of knowing which pups inherited what, unless the problem surfaces. By that time, I could have several generations of carriers and without a DNA test I can’t tell who is carrying and who isn’t. Most canine diseases do not have a DNA test.
Only if those physical traits are themselves negatives, particularly if exaggerated. For example, I linebreed for sound structure among other things - haven’t gotten any serious negative trait from doing that yet. Actually, I have yet to have experienced any serious negative physical or mental traits as long as I have stayed within the line I am linebreeding on, which is over 50 years old. The few times I have produced dogs that couldn’t pass the breed specific health checks (hips, eyes, heart), the condition was so mild that the dogs never showed symptoms. Of course, those dogs weren’t bred from since I am linebreeding in order to fix the good traits while attempting to completely eliminate the bad ones (which probably isn’t possible).
Why do you think that?
OK, that article said next to nothing. It is just a stub from a study that is apparently not online, making claims that inbreeding creates health problems without providing any proof. If the study shows the same old results that they all do, they will “discover” that using a highly popular male at stud frequently without concern for what health issues he may carry tends to create many descendents with health problems - surprise!
Oh please. Humans don’t even tend to consider whether or not their partner is fertile before they start trying to reproduce! Note the rising frequency in IVF and other artificial means of reproduction.
Why would you think that? This cite states there are over 1500 diseases in humans caused by one gene alone - it doesn’t say how many are caused by more than one gene. Compare that to the last study I have seen on dogs, which was done by a biased source, and even they could only come up with around 300.
You do realize this is an ongoing research, and that, unlike human medicine, there is just not that much desire/funding/interest in looking for genetic defect as cause of disease in pets (as compared to humans)?
Since you probably has done some literature review (and I have to leave the computer shortly), would you mind giving the reference for your last sentence?
So far as we know, the diseases associated with gene defects may be less in dogs than in humans… right now.
BTW, I’m still partially confused as to how this debate (and human tangent) came about in this thread.
See assertion in post # 10.
I really have no idea how much research is going on looking at genetic defects in humans, but there is quite a bit going on in dogs. One reason is they use that research for humans at times, another is that the average purebred pet buyer seems to feel that we can and must produce perfect puppies that will never be sick, so there are companies making big bucks developing and selling DNA tests for genetic diseases in dogs.
If you are talking to me, you’ll need to specify which last sentence you are talking about.
OK, right now there are thousands more in humans than dogs.
The OP indicated a belief that purebred dogs must suffer from genetic disease.
The paper mentioning the amount of genetic diseases in dogs that have been identified.
YMMV. It has been shown that purebred dogs (and cattle, and cats, and purebreeds in different animal species) have an increased risk of having certain diseases, and some of those diseases have been shown to have a genetic component.
Are they all defective? Nope, but they sure are carriers (and victims) of various genetic diseases/defects.
I didn’t see the tone in the OP as saying that ALL purebred dogs are carriers or suffer genetic diseases. More likely, he was just wondering if diseases associated with certain breeds have been found in animals other than dogs (answer: yes).