In this conversation yesterday, a common question came up: can you breed a Chihuahua and a Great Dane? It seems like it ought to be doable in one direction, if you cross a tiny little Chihuahua male to a large Great Dane female, but the question is what will happen if you cross a Great Dane male to a Chihuahua female — does the female swell up with giant puppies inside her until she looks like a watermelon with four tiny legs sticking out to the side, and then she explodes? That’s the cartoon version, anyway. I threw out my general recollection that no, fetus size is maternally regulated, so that doesn’t happen at all, but I didn’t recall any specifics, and said I’d look them up.
I did. It turns out there’s nothing but anecdotal bogosity out there on the interwebs. A lot of people cite this blog post from Ponderings from Pluto.
“It took a lot of trial and error,” said Marty Samson, a canine researcher with the University of South Texas. “At first, we tried having a Great Dane impregnate a Chihuahua, but that didn’t work: the puppies’ heads were bigger than the Chihuahua mother. We tried to deliver the puppies through Caesarian section four weeks early, but they were not viable enough to survive on their own.”
Neither the Great Mexicans/Chi-dane-danes nor their Chihuahua mother survived, leading Samson to conclude the only way to breed the dogs was to have a male Chihuahua mate with a female Great Dane.
Samson’s team had to erect a ladder for the male to climb since, even with the female Great Dane laying on the ground, his climbing on top of her was similar to an adult man having to climb a small structure.
Hey, everyone! It’s a satire site. It’s fake news. It even says so on the blog. I decided to check it out anyway, just in case. First problem: There is no such thing as a University of South Texas. There is a South Texas College, a Texas Southern University, a University of Texas Southwest, etc. But nope, sorry, we can’t ask the IRB at a fictional university to explain what they were thinking to allow this experiment.
I went further and checked PubMed, and there actually was an MD Samson who published a couple of papers in veterinary journals in the 1980s. They were not breeding experiments.
Other people cite Reddit (ugh, please). Nope, this is garbage, too. I also checked Snopes, just in case, but no joy.
It seems that either the experiment has not been done (purebred dogs are expensive, and owners are usually solicitous about breeding them appropriately; it’s also quite likely that this kind of research might be frowned upon as pointless), or it has been done and failed. It’s entirely possible that the two breeds are not interfertile. Or it may have been done, and the results were mundane and uninteresting, and not at all noteworthy.
I’m going to guess at the latter likelihood. I hit the developmental biology textbooks, and while it didn’t have the specific Chihuahua/Great Dane cross, Ecological Developmental Biology did describe a similar experiment in horses. Shetland ponies are small horses, less than 4 feet tall at the shoulder. Shire horses are huge draft horses. What if you cross them? The reciprocal crosses have been done, and no female Shetland ponies were exploded in the process. This diagram summarizes the results of the crosses.
The answer is simple: fetal size is regulated by the mother, and the foals are always of a size appropriate to the maternal breed. That makes sense; growth would be limited by the availability of maternal nutrients. The size of the offspring in different crosses are also correlated with uterus and placenta size. There is also evidence from human children.
When the same woman has borne children with different men, the birth weights of the babies are usually similar. However, when the same man fathers children with different women, the birth weights are often very different.
The final answer: the definitive experiment either has not been done or has not been reported in a credible source, but on the basis of other experiments, I’d predict that a Chihuahua mother would give birth to Chihuahua-sized puppies, no matter how big the father dog.
Is it possible that the crosses might produce tiny Great Danes or huge Chihuahuas if the puppies mostly take after their fathers?
So what happens if you impregnate an egg from female Chihuahua with the sperm from a male Great Dane, and then implant the egg in a female Great Dane?
(I am deliberately ignoring here that most(? all?) dogs have litters with multiple puppies. This may be a spherical cow assumption.)
The sense I get is the fetus would be small (appropriate for the Chihuahua egg donor), but at this point am stuck: Can the substitute mother even give birth to a significantly-undersized (for her) puppy? Will the puppy develop “normally” — whatever that means in the case of such a hypothetical cross — in an oversized (for it) womb?
(I’m obviously not a biologist, so apologies for any incorrect terms or other confusions. Corrections very much welcome!)
That may (always?) be true for intraspecific crosses, but at least one cross between sister species results in overgrowth of the fetus and death of the mother.
When I was a teenager, my cousin had a particularly small female purebred Chihuahua who, due to some poor pet supervision, ended up pregnant by an Australian Shepherd mix. (I assume some careful crouching was involved.) She carried the pregnancy in a perfectly normal fashion until she went into labor, at which point she showed signs of more pain than typical and was failing to progress. We took her to the animal hospital for an emergency C-section. She was pregnant with four puppies–which would be physically impossible if they were anywhere near Australian Shepherd size–and one was tucked into a position that was making delivery difficult. It’s exactly the sort of complication that can happen to any birthing mother, having nothing to do with the breeds involved at all. Puppies were handed over to those of us assisting and we massaged them until they were responsive, just like any other puppies delivered this way. The veterinarian convinced my cousin it was the responsible pet-owner decision to have her Chihuahua fixed and they removed her uterus then and there. (They were even kind enough to let me examine it afterwards, awesome!)
In adulthood the puppies grew to be larger than their mother and smaller than their father, completely unsurprisingly, but they were all born Chihuahua sized. Possibly slightly larger than average, but within the breed’s range.
I’d certainly agree.
So are you saying that Shaquill O’Neal could mate with Nadia Comenici? That’s crazy talk. She’d explode. And Ron Turcotte would need a ladder to get at Rebecca Lobo, and produce an itta-bitty Turcottette.
I’m reminded of the famous Stephen Jay Gould essay about why horse-zebra crosses have more stripes than zebras.
Gag from an ancient Tonight Show:
Johnny: It says here that a great dane had puppies that were fathered by a chihuahua
Doc: Somebody must’ve put him up to it.
#3: yeah, it would have to be intraspecific, so the two sexes would have coevolved. Diverge too much and you get other effects.
This is consistent with my life experience: the dam determines fetus size. I live on a farm and raise animals. This is what I have observed in my lifetime.
In one case I had the foal of a very small mare (about 30″ tall at the withers) bred to a stallion who stood about 62″ tall (15.2HH aa we say). We’re not sure how they worked this out: both escaped during the night and by morning the deed was done. The resulting foal caused no problem for the dam to birth, but grew to be about half way between the size of the two parents. Due to this experience I am not real concerned if the sire is bigger than the dam. I do make sure the sire in question is a well-adjusted member of his species.
Fwiw: A friend in the remote mountains of New Mexico recently adopted a domestic-cat mother/bobcat father mix (the mother made it through the birth but succumbed to an unknown predator soon after). The kitten is reportedly about half grown and rowdy, but learning well.
With almost anybody else, I’d worry about safety of both adopter and adoptee, but that particular mountain woman knows her animals.
Toy breeds are very prone to making puppies too big for them to birth, and the fewer their puppies the larger they are. It’s a really big problem with chis and results in the fact that they are commonly seen for dystocia.
OK. Puppies are one thing. How much effect does birth size have on adult size?
I don’t know the original context of the question here, but it seems an important one (regarding incipient speciation, even if accelerated by artificial selection in this case). Creationists are always complaining about an inability to see “evolution in action” (i.e. speciation) in the time frame of recently recorded human history, despite some pretty dramatic examples of changes incurred by domestication. The developmental question here notwithstanding, I think it would be extraordinarily difficult for great danes/St. Bernards, etc. to copulate with chihuahaus/dachsunds (either way). A cross would have to be done artificially – “careful crouching” would be nigh impossible… So there may well be behavioral (if not physiological) barriers to reproduction, and de facto speciation (depending on one’s species concept). In that way I think of dogs as a sort of parallel to ring species, with the ends being the largest and smallest breeds in this case; but one in which we’ve not only “seen” the change happen, but instigated it ourselves.
I can’t believe nobody has mentioned this. (Lyrics by Eric Bogle)
“Oh, I used to have a doggie and I called him little Gomez
For you see he was a Mexican chiuhuahua
There wasn’t much of him but what there was was all cojones
He really was a randy little feller
Big dogs, small dogs, it mattered not to him
The canine equivalent of Errol Flynn
At the drop of a sombrero he’d jump up and get stuck in
Taking Gomez out for walkies was embarrassing
I remember one day in the park his tally rose by four
An enviable score he was amassing
A pair of high-strung poodles and an Irish Labrador
And a wombat who just happened to be passing
I tried every way to curb his carnal appetite
I kept him on a lead all day; I locked him up at night
I even put some bromide in his chunky Meaty Bites
But the only thing that might have worked was kryptonite!
Then there came the fateful day when he tried to consummate
A liaison with a Saint Bernard called Blodwen
And although he seemed to be punching well above his weight
He didn’t let that little detail stop him
He nearly pulled it off! Oh, what an acrobat!
But Blod got bored and down she sat.
Well, they say that after making love you sometimes feel quite flat
And I’m sure that little Gomez could agree with that.
I buried Gomez in the park – his happy hunting ground
A sad but fitting finale
I had to dig a grave that was rather flat and round
For he looked like a squashed tamale
But I really missed my wee chiuhuahua chum
I went down to the pet shop to buy another one
I went in feeling happy and I came out feeling glum
Cause the man who ran the pet shop loved his corny puns
And he said “Yes! we have no Chihuahuas
We have no Chihuahuas today
We’ve Alsatians, Dalmatians, and the fruits of a flirtation
Twixt a half-blind Pekinese and a toupee
But yes! we have no Chihuahuas
We have no Chihuahuas today.”
Video at https://www.youtube.com/watch?v=QoDTef6pDg4, for those who are interested.
Our oversized labrador was accosted once on his afternoon walk by a very in season Jack Russell bitch. She was delighted with him. He though could not seem to associate the wonderfully interesting smell with this tiny thing and kept looking round for the source. So no puppies. Fortunate all round probably.
I go to my local dog park often. See a lot of interesting mixes, like mastiff and toy breeds. I’ve seen a great dane + small dog mix (can’t remember which, not toy though – yes, we stood around and wondered how that happened). Most of these are the parent dogs are pure, but they get out while in heat, have puppies with the local pure breed male, and the breeders don’t want the puppies, so they go to the shelter. However, great dane + boxer or terrier (pitbull) are done on purpose and are easily found for sale. The adult dogs come out to be a size in-between the parent breeds. So yeah, it’s possible, but not ethical. We’ve too many unwanted dogs as it is.
Now that this is solved I want an explanation for corgie mixes.
+++
Our neighbours box was once courted by a dachshund. Everybody was speculating how that would happen, but being responsible dog owners or neighbours didn’t put the various theories to the test.
My mother’s childhood corgi mix mated with something enormous. Her belly was literally dragging on the ground by the time she went into labor and she required a cesarean to remove the four puppies. Those puppies were as large as their mother at three months old and so apparently so ugly they couldn’t even give them away like they did with her first litter.
Well, there’s at least a couple of breeds of cattle that have excessively large calves–more than the cow can handle. These are the Belgian Blue and Piedmontese breeds (https://en.wikipedia.org/wiki/Belgian_Blue), which have a genetic change in the production of the myostatin protein, resulting in overproduction of skeletal muscle. Birth requires Cesarean section, making these breeds generally uneconomical, not to mention something that would never make it in the wild. Apparently, they only make sense for increasing meat production for really small farms.
@Gilell #16:
I think people just look at their purebred dog, asking “what would it look like with stubby legs?”, and the rest is doggy history. Although I think the Husky/Corgi mix is just so they could have a breed called a Siborgi. There’s probably a similar explanation for Bulldog/Shih Tzu mixes and Poodle/Labrador Retriever mixes. The former is self-explanatory, while the latter is the result of people really like saying “Labradoodle”.
Yes, very true in horses, but not in all species. Fetal-maternal pelvic disproportion is one of the most common causes of dystocia in dairy cows. Most cows are inseminated via AI; bull semen is selected based on how much milk their female offspring produce, with no consideration given to size of each of the parents. I agree with you though, I doubt there would be research into this in dogs since they do not have the economic significance of horses and cows that have been studied more extensively.