what is wrong with people-----selling puppies....

[LoupGarou]

There is no such thing as hybrid vigor for two breeds of the same species. A mule has hybrid vigor because it is the result of crossing a donkey and a horse--that mule is also typically sterile because they are true hybrids. A cockapoo has no hybrid vigor and remains fertile because it is nothing more than a cross-breed. A first generation cross-breed might have limited "hybrid vigor" if the genes for the diseases that the parent breeds carry are dissimilar.

That is, a rough collie crossed with a Gordon setter might not have susceptibility to PRA and the mutant gene that makes certain drugs and vaccines fatal to herding dogs; however a rough collie crossed with a border collie would not even have that limited hybrid vigor, since both are prone to PRA (with the added bonus of glaucoma from certain BC lines) and both are white-footed herding breeds that are prone to the mutant gene. Even dissimilar breeds can carry similar genetic diseases, however. Congenital hypothyroidism with goiter (CHG) has been detected in numerous breeds, but only a few have genetic tests that identify carriers.

So, by way of an example, let's say that a medium-sized American Cocker Spaniel runs loose through the neighborhood and breeds the Toy Fox Terrier and the Golden Retriever on opposite sides of its owner's property. The TFT and the ACS share patella problems and potential eye problems (both have slightly prominent eyes), the ACS and the GR share hip and elbow problems and possibly skin and coat issues as well. No hybrid vigor there. Now, in six months to a year, puppies from both of these litters get together and produce more puppies. Not only do they share all of the genes for the ACS issues, but TFTs and GRs share the genes for CHG, which is a disease that is inevitably fatal to affected puppies, who die of strangulation by the time they are three weeks old. If this generation is lucky, they've dodged the bullet, but if one or both of them carry the gene for CHG, their puppies will either be carriers or be affected by this disease. These dogs, if not spayed or neutered can go on to breed with the Doberman down the street (Wobbler's, cancer, hip and elbow issues), the Boxer one road over (cancer, hip and elbow issues), the Miniature Pinscher (sebaceous adenitis, cancer, eye issues, patellas), the Miniature Poodle (sebaceous adenitis, patellas) and so on, creating a veritable cornucopia of hereditary diseases to affect future generations at random.

There is absolutely no hybrid vigor in fertile animals of the same breed beyond one generation and sometimes it doesn't even last that long.

Anyone who breeds solely for profit and not for health and the eradication of disease (also known as "improving the breed) is irresponsible and doing a disservice to dogs. People who create deliberate cross-breeds for deliberate purposes (the Labradoodle experiment, creating a new breed that has a standard, the bob-tail Boxer experiment) keep these diseases in mind and typically seek to eradicate them as they continue their work.

Mixed breeds happen. I don't mind seeing accidental cross-breeds. I see absolutely no reason for people to profit on dogs based on cross-breeding.

 

[Chicks_N_Horses]

I have a female pom. If she were to get pregnant, say by the daushaund down the road and someone offered me 100$ for them....I would say SOLD in a heartbeat. That is what I meant. I am sure most people would...even the ones who like to have the holier than thou attitudes I'm sure...

I've had 3 purebred dogs in my life. A cocker spaniel, yorkshire terrier, and our pom. The cocker and yorkie were not as healhty as the ones I have now...a pit/american bulldog mix...a lab/springer spaniel mix. The pom is pretty healthy though, she hasn't ever been sick yet.

I just base things on my own experiences/things I've read...never claimed to be an expert...

 

[SpringChickens]

LoupGarou,

I agree completely that we need more dog breeders who are out for the welfare of the animal, not just the bottom line. However, hybrid vigor absolutely occurs in all mixes, well beyond the F1 generation. Hybrid vigor does decrease in later generations, but only if you breed the F1 generation to each other.

To create a "purebred" animal, you need to breed animals with the desired traits until these traits are solid, and the animals breed true. The reason these traits breed true, is because the offspring now have two copies of the desired gene. ALL breeds (that I know of) originated from foundation stock, which was line-bred to propogate the desired results. This practice also results in the offspring having two copies of "undesired" genes as well. When you cross to an unrelated animal, you get hybrid vigor, even within the same species.

The reason purebreds are more likely to have diseases such as hip dysplasia is because you are utilizing the same genetics for these animals, for good and for bad. Most of these diseases are recessive diseases, requiring for the mother and the father to be a carrier. When you breed these animals to animals of a different breed, you only get one copy of the said recessive gene, and voila, hybrid vigor.

That said, this isn't always foolproof because you may breed a lab to a german shepard, both of which are known for having hip dysplasia. If it is the same gene which causes hip dysplasia in both breeds, you have similar chances of getting offspring with hip dysplasia.

In cattle, they breed angus and hereford together for hybrid vigor, as well as MANY other breeds. One of the most popular animals to cross with is Brahman cattle because their genetics are further removed than the rest.

That said, I love my mutts, but they are both spayed and I have no intention of ever bringing more dogs or cats into this world.

 

[Suellyn]

It's true that purebred dogs DO usually have some health issues associated with the breed. The point is, that they are usually specific and identifyable issues.

Therefore it is much, MUCH easier to breed selectively/responsibly (by testing parents) to help ensure that these issues DO NOT occur, or at least chances are minimized.

As LoupGarou illustates, this is *NOT* the case with crossbreeds... There are a GAZILLION possible health issues that they could have. However, it is much harder to predict/prevent because of all the variables in geneticts!!

I think the idea of "hybrid vigor" in crossbreeds occurs *NOT* because they are healthier, but because it is almost impossible to make specific health associations & predictions for them.

In contrast, a lot of breeds have had outstanding health issues identified, which to me is a POSITIVE thing (because you can be pro-active with breeding & screening), yet because there is an association between a BREED and a specific issue, the myth of "breeds are weak, mixes are healthier" persists....

And I do understand and agree with new bloodlines needed to prevent the inherent risks of inbreeding, but again, it is a controlled, well researched decision based on the genetic diversity within the breed that determines if you infuse with a different bloodline of the same breed, or need to introduce genetics from a different breed to improve & "buffer" the original one...

 

[RachelFromTheBlackLagoon]

Quote:
No, I mean other countRies. Middle Eastern countries, Mexico, China. They come from American territories/protectorates, too, such as Guam and Puerto Rico. California shelters receive a lot of pups from Mexico, many of which are smuggled right over a porous border. Puppies from other countries are actually a pretty big issue. Just because you can't bring yourself to comprehend the enormity of the problem because you are so close to it, it does not mean that the problem does not exist (and I mean that in the least snarky way possible).

I'll look into that when I have a chunk of free time. I've never heard of such a thing and don't understand why anybody would do that just to fill a demand... I know there are people who rescue dogs from other countries. Someone mentioned the Potcakes earlier, there's a vet the next town over that goes to the islands and spays and neuters several at a time and also brings back litters of puppies. The dogs there are feral, they have to scavenge for food, they're often subject to starving or abuse. It's really sad. He quarantines the pups, fully vaccinates, speuters and adopts them out. I've heard people argue that the US needs to save its own dogs, but these guys need help, too! I sort of have mixed feelings about it but I think he's doing a good deed by helping these dogs. I have a very difficult time believing that people who do these rescues are doing some sneaky, underhanded, malicious thing. They're trying to help dogs in general. I can see how somebody who breeds, often gets blamed for overpopulation and is afraid of breeding bans would use that as an arguement. There are a lot of people in rescue who understand that there's a HUGE difference between BYBs and mills, and legit responsible breeders. BUT there are also many that lump them all into the same category and label them "horrible". It's crazy to think they're one in the same. The way I see it is, legit breeders do everything they can to help dogs and so do rescuers. It may be in different ways but we all love them and are trying to help, just the same. We need to stop playing the blame game! We know who is at fault! We need to work together to educate people about why things like careless breeding and buying from pet stores are such a problem.


To whoever mentioned the pit bull thing, that drives me nuts, too! My shelter always has tons of pits and pit mixes, and most of the time they come in unaltered. It's very sad that most shelters don't even attempt to adopt them out, they're just automatically euthanized. And these poorly bred, unsound dogs give the rest of the breed such a bad name... It's got to stop!!

 

[LoupGarou]

Hybrid vigor does not exist beyond the first generation. If you attempt to breed the F1 pups together to fix the traits, they 1) will not breed true and 2) they will lose the diversity of genetics (heterogenesis) that created the vigor in the first place. If you breed to other dogs from the parent breeds, genetic diversity is lost, reducing the vigor. The same loss of diversity/vigor continues with each generation. Don't take my word for it:

From the failed Australian Labradoodle breeding experiment.

It should be noted that it is well regarded and recognised that hybrid vigour or heterosis effect is 'strongest' or 'highest' in the first generation of progeny produced from the crossing of the two purebred breeds, such as in Labradoodles. That is, when the two parents are purebred (eg Labrador Retriever and Poodle) and are crossbred, their progeny or offspring have the most hybrid vigour or heterosis effect. And this first generation of progeny or offspring are commonly referred to as the F1. And the next generation F2, etc, etc.

If, for example, you were to then breed an F1 progeny to another F1 progeny, then the hybrid vigour or heterosis in the progency or offpsring produced would be significantly lower than in the F1 generation. And the further down the generations you continue (eg F2, F3, etc), the hybrid vigour or heterosis continues to diminish to the extent that it is insignificant.

Some breeders, for example, of mixed dog breeds such as Labradoodles, even further minimise hybrid vigour or heterosis by 'back breeding'. For example, they may breed an F1, F2, etc back to one of the original purebred breeds (eg Poodle). And may even deliberately continue this practice, in attempts to 'strengthen' a desired characteristic in the offspring or progeny (eg the soft curly coat of the Poodle).

http://articles.directorym.net/Hybrid_Vigour_With_Mixed_Breed_Dogs-a943738.html

If you read the entire article, you can see the definition of "hybrid vigour" as operationalized by New Zealand researchers.

In addition, The Journal of Animal Science has published at least one study that shows little difference between the "carcass traits" of purebred and cross-bred cattle:

Growth and carcass data on 7,154 cattle from a purebred project and 1,241 cattle from a crossbred project, comprising 916 first-crosses and 325 purebred Brahman controls, were analyzed to estimate genetic parameters, including the genetic correlations between purebred and crossbred performance (rpc). The data also allowed the estimation of sire breed means for various growth and carcass traits. Crossbred calves were produced using 9 Angus, 8 Hereford, 7 Shorthorn, 14 Belmont Red, and 8 Santa Gertrudis sires bred to Brahman dams. These same sires produced 1,568 progeny in a separate purebreeding project. Cattle in both projects were managed under two finishing regimens (pasture and feedlot) to representative market live weights of 400 (domestic), 520 (Korean), and 600 kg (Japanese). The traits studied included live weight at around 400 d of age (400W), hot carcass weight (CWT), retail beef yield percentage (RBY), intramuscular fat percentage (IMF), rump fat depth (P8), and preslaughter ultrasound scanned eye muscle area (SEMA). Estimated breeding values (EBV) of sires from their BREEDPLAN genetic evaluations were used to assess their value in predicting crossbred performance. Regressions of actual crossbred calf performance on sire EBV for each of the traits differed little from their expectation of 0.5. Angus sires produced crossbred carcasses with the highest P8 and lowest RBY but highest IMF. In contrast, crossbred progeny from Belmont Red sires had the lightest 400W and CWT, lowest P8, and highest RBY. Estimates of rpcwere 0.48, 0.48, 0.83, 0.95, 1.00, and 0.78 for 400W, CWT, RBY, IMF, P8, and SEMA, respectively. Commercial breeders selecting sires for crossbreeding programs with Brahman females, based on EBV computed from purebred data, might encounter some reranking of sire’s performance for weight-related traits, with little expected change in carcass traits.

http://jas.fass.org/cgi/reprint/80/7/1801

I'm not saying that hybrid vigor does not exist when two breeds are initially mixed; however, it would be erroneous to state that hybrid vigor between animals of the same species continues in any significant manner beyond F1.

 

[SpringChickens]

Suellyn,

You made some good points. It's very true that purebreds do tend to have known health problems, and it is absolutely easier to avoid these health problems when you know what you are looking for.

A cross-bred animal is LESS than the sum of his parents, as far as diseases go. This means that, when you breed a german shepard to a poodle, you only get one copy (at most) of the hip dysplasia gene, and only one copy of the poodle disease gene (whatever that may be). The F1 generation is LESS likely to have serious genetic diseases because it comes from a more diverse genetic background.

Your argument that they could get more diseases because you don't know what their background is doesn't hold water. You know the diseases of Mom, you know the diseases of Dad, it would be VERY unlikely to have two genes combine to form a new disease in the offspring. Mom and Dad are genetically much more similar to animals of their own breed than to each other.

Interestingly, the F1 generation in cattle typically gains weight and has higher resistance to disease than its mother or father had.
Cross bred cattle recently had the following increases compared to purebred cattle - daily gain preweaning (13.63%), weight at weaning (11.3%), daily gain postweaning (61.64%), weight at 18 months (10.67%). (Arango et al. 2000).

 

[SpringChickens]

LoupGarou,

You are completely correct. I believe I said the same thing you just did in my first post. Hybrid vigor weakens during every subsequent generation, but this is because you are, again, breeding same to same. This causes the next generation to have a lot of double copies of the same genes, which strengthens desired traits, as well as undesired traits.

ETA - I claimed no difference between carcass traits, just difference in the average daily gain, and in general health. I would expect muscling to decrease in the F1 generation of Angus X Brahman because the Brahman is a lighter muscling animal.

 

[Chicken Fruit]

Its ridiculous. You can get the same friggon animal at the shelter for 50 bucks, and save its life. I am not against breeding animals for sale, but some of these people are just out of control. We have breed standards that are recognized and controlled because they mean something to the group as a whole.

I dunno... its a fine line between pushing the limits and just being ridiculous.

 

[LoupGarou]

I'm not sure what the issue is, then, SpringChickens--my posts have always stated that there is no benefit from hybrid vigor after the first generation. Were you refuting or reinforcing my posts? Regardless, I have to make the point about the GSD to poodle cross. If someone were to mix the GSD with a TOY poodle, I would agree that there would be less of a possibility of hip dysplasia (HD). However, if the GSD were bred to a STANDARD poodle, then the resulting offspring is just as likely to have HD as a GSD to GSD cross.

The problem with both hip dysplasia and luxating patellas (LP) is that the are caused by multiple factors and not by a single genetic factor. Therefore it is easier to eradicate something like CHG from a gene pool than it is to eradicate HD or LP. It's the same thing with something like von Willebrand disease (VWD), which appears in many breeds but appears on different genetic markers.

Canine genetic diseases are very interesting and very complex. As someone stated, with parents of the same breed it is easy to determine what genetic diseases must be selected for--it's not so easy to do that when the parents of different or undetermined breeds that might share genetic characteristics.