[Cronos]

The germs just fell over the place :)

Take the example of what happened to the native Americans in what is now the USA.

In the 1500s, Europeans hadn't penetrated this area and when they did they found empty lands or abandoned places. The germs went ahead of them -- when the Spaniards landed in the late 1400s in Mexico, their contact with the natives spread disease. Then due to trade, war etc. the germs rapidly spread north

That was why 90% of native Americans died by germs and the vast majority without even SEEING a European

I would say that the same happened to the dogs

These aren't about dogs getting human germs but dogs possibly picking up a disease brought along by European dogs

The FACT is that the indigenous dogs died out and the Eurasian varieties "replaced" them

The most likely answers are

1. that they died of diseases brought along by the Spanish Fidos :)
2. They were heavily dependent on their owners and when the owners died, they died out too - outcompeted as feral dogs by wolves or Euro dogs

- Europeans didn't eat dog meat mostly and they would not kill a dog on sight.

[Boomer]

Now that makes more sense.