"Runt" syndrome? (vet, cough, adopted, kennel)

[ssg II]

Since our babies were adopted, we'll never know their exact mix, etc., but these are the facts: They are litter-mates. "AJ" is the epitome of a Norfolk Terrier, as described by the AKC. His sister, "Sunny," outweighs him by almost 5 lbs., has longer legs, therefore taller and has much softer and thinner fur.

Sunny is a very healthy dog. Sadly, AJ has problems. When we took him to be neutered, one of his testicles hadn't dropped. Then he caught kennel cough, from the Humane Society, I assume, it manifested shortly after we got them home. Last year, after a very scary couple of days when he couldn't jump & his tail was down, we discovered he has invertebrate disc disease and at this year's check-up, the vet found a heart murmur, scale of 1 to 6, he's a 1. Sunny is more independent and AJ, though the premier guardian of the house, is the snuggler, the mama's baby, wanting constant pets.

So, my questions are: Might he be the runt? Do runts typically have significantly more health issues? Would that make him more likely to crave attention and closeness? (He's always right next to me in bed, usually backed right up to my shoulder.)

I've asked my vet these questions, but obviously, I get a "might be." What do you all think?

Thanks for your thoughts. I'm getting panicky everytime AJ gets lethargic, thinking his immune system has let him down again, that something else is wrong.

[irishmom]

Could simply be two different fathers. Happens all the time and that could explain the big differences in size, looks and health...coming from two different blood lines. Often males are much more affectionate than females who tend to be a bit more independant, which could explain the cuddling difference as well. Good luck with both of them.

[pinetreelover]

As a neonatal nurse I am very familiar with what we term WWM syndrome (Wimpy White Male Syndrome). White baby boys just don't do as well as their female or African American counterparts. Maybe there is a similar doggy syndrome!

[ssg II]

Two different fathers? Guess I always assumed once the eggs were fertilized, that was it. That WOULD make sense. And if the mom was a pure-bred and only one of the fathers was, well that would make sense, too, in that AJ has all the characteristics of the breed and Sunny doesn't.

WWM? Something else I was ignorant about. Both my younger brothers had health issues as infants but, (I'm the only female sibling,) I never did. How interesting.

Thanks!

[LingLing]

Your male dog AJ may inherit defective genes that located on X-chromosome. Your dogs' mom is normal because she has normal genes on one X-chromosome and defective genes on another X-chromosome. The good genes compensate the defective genes. Your dog father has a normal pair of X-Chromosome and a Y-chromosome. Your girl, Sunny will inherit one copy of X-chromosome from mom and one from dad. No matter the good copy or the bad copy from mom, your girl always has a good copy from Dad. Your girl should be normal. However, as a boy, AJ can inherit a bad copy of the X-chromosome from Mom and a Y-chromosome from Dad (Remember, boys don't have two X-chromosomes). Since there will be no good copy of X-chromosome to compensate the defective genes, AJ will have all the phenotypes of the defective genes on the bad copy of the X-chromosome, thus AJ may appear to be small and get sick all the time. If there is another litter from the same parents and 50% of boy has the similar syndrome, then it is likely AJ's problem came from the defective genes on the X-Chromosome. If it is a human's baby, researchers will do genomic walking to find defective genes in order to find a cure.

[ssg II]

Sorry I never thanked you, LingLing. Worried about AJ, lost the thread, whatever.... no excuse.