If you’re a type 1 Diabetic, do you stop being diabetic if you cut sugar out of your diet? If you have a genetic predisposition to alcoholism or drug addiction, do you prevent having alcoholic children if you abstain from drinking? If you’re allergic to peanuts do you cure the allergy by not eating peanuts?
You can prevent, limit, or forestall manifestation of a disease path with nurture, but this doesn’t mean that the disease path itself originates in nurture or behavior, and managing it in this generation does nothing to solving it in the population as a whole, especially going forward.
If your collie is MDR1, you don’t solve the disease simply by NOT giving them MDR1 drugs. It’s still there. The weakness will be passed on.
This is not a profound idea, but it’s a concept that I see abused regularly, even by people who claim genetic literacy.
Example 1: Uric Acid disease in Dalmatians
All traditional Dalmatians are homozygous for the disease gene causing Uric Acid disease. All of them have two copies. There’s no diversity on that one gene in the breed.
And yet all Dalmatians don’t suffer the problems the same. Does this mean the disease is not genetic? No. Does this mean that the best path to limiting the disease is a nurture strategy versus a genetic strategy? No.
The renal disease of the sort Dalmatians get is fleetingly rare outside of Dalmatians. Other breeds can safely process purines in their food and don’t produce excess uric acid which leads to kidney stones. We can give Dalmatians a special diet which tries to avoid the disease much like denying a genetic-alcoholic booze or avoiding peanuts for someone with the allergy.
Before the High Uric Acid gene was identified, you could even run an analysis on the disease expression across generations showing that its “heritability” was some X percent where X is less than 100. Meaning that if both parents had kidney stones, not all of their children necessarily would.
Idiots use this number to say that “it has a genetic component but is not fully genetic.” This is stupid, especially when we artificially limit our view to a population that is all essentially the same genetically.
“Not all Dalmatians get High Uric Acid disease! Therefore it’s food and we can manage food so we don’t have to change our gene pool!”
This ignores that of all the cases of HUA disease almost every single one comes from a dog with two copies of the bad gene. You can certainly alter nurture in an unaffected dog and get them to express the disease, you could overdose them massively on uric acid, overwhelming even their normal ability to process it. Sure.
But this no more makes the disease nurture than genetically homozygous Dalmatians not getting it frees it from being genetic.
Genes aren’t assured destiny. Expression is variable. Penetrance is not absolute. So what? This doesn’t change one thing about the strategies that must be employed to improve health in dogs. And yet all too often people who DON’T WANT to outcross use this uncertainty as some justification.
“I can manage my dog’s food and get somewhat better results, so I won’t dare consider outcrossing to introduce a healthy allele and eventually breed out this problematic allele. That’d be totally uncalled for!”
The logical solution is to zap that gene and not require an entire breed to be fed a special diet to avoid disease expression.
Example 2: Hip Dysplasia is caused by kibble?
Carol Beuchat has an article about Hip Dysplasia in dogs that points to kibble as the culprit, specifically too much of it.
The results of a study show a delay and a decrease in expression of HD in dogs feed less, who are presumably less fat, which presumably puts less stress on the hip joint, which would lead to less disease expression.
This is no more profound than not feeding peanuts to an allergic, preventing an alcoholic from drinking, and stripping the Dalmatian diet of the compounds they are unable to process normally.
It’s nice advice to people and it will certainly lead to less pain in dogs, but it’s no cure. It speaks nothing to the actual cause of the disease. Putting less stress on a weakened joint doesn’t cure the joint, it just doesn’t accelerate the disease as fast.
And yet Carol can’t help but say dumb things.
It seems clear that it has some genetic component (it is thought to be polygenic) but there are clearly environmental (i.e., non-genetic) influences as well.
This is boldly meaningless. Almost every single disease can be said to be both genetic and environmental. But not in equal measure, which is usually the next stupid thing said. It’s both, therefore it’s both equally and also therefore I don’t have to do anything about one because I can or can not control the other!
I can control the environment, therefore I don’t need to address the genetics. Or I cannot prevent X in the environment therefore it’s going to happen anyway at some rate and damn you if you remind me that genetics could drastically lower the rate no matter what the environment presents.
There has been some modest success in reducing its incidence in some breeds by screening programs, but for the most part it remains an intractable problem and the focus of many research programs.
Translation: Breeders have done next to nothing useful in combating HD in their breeds because they refuse to employ the most potent tools, like outcrossing and accelerated breeding and culling (which is how HD was bred out of many sight hound breeds). What breeders have done is said, heck, we’ll not stop our drinking but we agree to call a cab when we’re blotto and we’ll go to the hospital when we get alcohol poisoning. This decreases a few deaths here and there, so woo hoo. It does not, much like trying to breed out HD from within a closed pool with high saturation of the genes that cause it, remove the genes very fast.
In Dalmatians, it would be IMPOSSIBLE to breed out HUA disease because it was 100% saturated. It was FIXED in the gene pool.
So “breeding away” from the dogs that were diagnosed would do nothing, much like it did… it did nothing for all the years people tried to breed away from it from within the pool. Only the outcross made breeding away from it possible.
With HD we don’t have the candidate genes, BUT WE KNOW THAT HD IS PROFOUNDLY GENETIC!
How can I say that? Because it is almost entirely absent in several sight hound breeds. You can feed THOSE dogs whatever you want, limiting their kibble will not make the disease stats go down, doubling it will not make the dogs profoundly dysplastic. You can’t turn a Greyhound into a Lab by feeding it like one, you can not make it dysplastic with the normal environment which produces profoundly dysplastic Labs.
So if the Dysplasia is SECONDARY to the gene pool, talking about kibble is a diversion from reality. Greyhound breeders don’t have to feed their dogs special diets for HUA or HD. Because genetics.
Genetics trumps environment, even here.
Consequently, I was quite surprised to run across a paper (1) published in 2006 about a study that was able to substantially reduce in incidence and severity of hip dysplasia in Labradors – not by locating particular genes or implementing strategically-designed breeding programs – but by reducing food consumption.
And guess what, any and all benefits of denying calories to the Labs would immediately stop producing a reduction in HD expression in any and all future generations where such a diet was not maintained.
This is management. Not treatment. Not prevention. Not cure.
Great news, though. It is something that can immediately be done to stop current dogs from suffering. But Beuchat doesn’t run a wellness blog. She runs a breeding blog and diet is not a breeding decision. Diet is not a population genetics matter. It’s not genetic counseling strategy.
It’s a patch on a faulty tire.
In each litter, puppies were paired and one assigned to the control group and one to the treatment group. The control group was provided food ad libitum (unrestricted) starting at 8 weeks, and each puppy in the treatment group was fed 25% less than the amount consumed by its pair in the control group. Their weight was monitored and hips x-rayed at regular intervals throughout the lifetimes of the dogs.
Dogs that were fed less had dramatically lower incidence of hip dysplasia. How dramatic? Have a look at these graphs (modified from Smith et al’s paper).
Dogs allowed to eat as much as they wanted showed evidence of hip dysplasia at younger ages than dogs fed less, and the difference between the groups got worse as they got older. By 6 years of age, 50% of dogs in the unlimited food group had evidence of osteoarthritis, compared with only 10% of dogs in the restricted food group. More than 50% of the dogs in the restricted food group still had radiographically normal hips at 12 years old; in the other group, 90% were arthritic. Dogs fed 25% less food than their pair in the control group weighed about 25% less throughout their lives. Heavier dogs had worse hips.
You want to know what’s missing here to make any statement about genetics? Another two control groups of Greyhound puppies fed in the exact same manner.
When none of those dogs would develop HD, you wouldn’t be fooled into saying such things like “some genetic component.”
If somebody was to submit a grant proposal to test a treatment that promised to reduce the incidence of hip dysplasia in dogs – not by 10%, or even 25%, but 50% – I should hope it would receive very serious consideration for funding. And what about the Canine Health Foundation and also the Orthopedic Foundation for Animals (OFA), which owes its founding to concern about the high incidence and crippling effects of hip dysplasia in dogs? A browse of the information on their websites about the disease makes no mention of this study or the potential benefits of lifelong food limitation.
Feeding Dalmatians a low purine diet (compounds that metabolize into uric acid) is a palliative. And frankly promoting it does more harm than good. It might help current dogs to not suffer, but it gives aid and comfort to the enemy: breeders who resolutely will refuse to do what is right for all future generations of Dalmatians by removing the disease entirely.
Feeding Labs less is a palliative. You can prevent wear on the joints and delay the disease, but the outcomes even with the low-calorie Labs were not spectacular. Their hips still went bad. Over 70% of them eventually went dysplastic. It bought them time though, more than half the more food Labs had HD by 6, the less food labs didn’t pass 50% until 12. Yay. But so what?
What is more likely: Getting the majority of Lab owners to restrict their dog’s diets or producing more sound dogs that will not get HD no matter how they’re fed, especially out of the normal given that we damn well know that the vast majority of any dog breed owners aren’t paying attention to studies?
Greyhound owners don’t need compliance from their owners.
“Less Food” – such a simple (and cost-effective!) way to substantially reduce the suffering of dogs, reduce veterinary bills for treatment, x-rays, and pain relief, and increase the amount of time the family dog can continue to lead an active life. Millions of dollars are spent every year looking for sources and cures of disease in dogs so that we can offer them better lives. Maybe we should direct some of this funding to an informational public service campaign to get this simple information to breeders and pet owners, and perhaps also some clear recommendations on dog food bags, maybe even brochures in veterinary offices.
Well meaning but stupid. Let’s divert resources from study which could solve the problem for EVERY future generation of dogs into advertising which will be an endless pit that needs to be filled every generation, forever, until someone actually manages a cure that doesn’t require owners to know and comply to some special diet.
I mentioned up top that there was also most certainly some genetic component to development of hip dysplasia, and that’s certainly worth talking about because there might be some surprises there as well.
Some? Again with the nonsense. All you need to remember is that HD was PURGED from a breed by genetic selection. Diet and environment be damned, it didn’t matter and the problem was eliminated.
Do you want an HD and HUA free breed or do you want a fussy food case that requires compliance to a so-so plan that might spare your dog some suffering, or not, but will do nothing to all the dogs in the future who you saddle with the same bad predispositions because “management” sounds more palatable to breed purists than doing something that’s actually an imposition like culling and outcrossing and preserving diversity while purging disease which requires strategies that aren’t nearly so easy as just going along with the corrupt current culture.
* * *
Comments and disagreements are welcome, but be sure to read the Comment Policy. If this post made you think and you'd like to read more like it, consider a donation to my 4 Border Collies' Treat and Toy Fund. They'll be glad you did. You can subscribe to the feed or enter your e-mail in the field on the left to receive notice of new content. You can also like BorderWars on Facebook for more frequent musings and curiosities.
* * *