Yorkies being bred as ratters does not automatically give them any immunity to any diseases, whether or not rats carried the diseases. If Yorkies Huddersfield Ben, (particularly) had any natural immunities to the diseases carried by the rats of those days, it is logically possible that today's Yorkies may still retain some immunity. I wouldn't count on it, though.
The big difference, IMHO, is that today's rats have evolved in a wide variety of changes in their environment. Whatever their adaptations, there is now considerably more to it than disease. Today's rats living in sewers in NYC, for example, undoubtedly consume or are exposed to vast quantities of toxins...degrading plastics, industrial cleaners, and medical waste, for example, that the rats that are not killed off by the toxicity will have developed some immunity and/or tolerance to. I doubt Yorkies have that 'advantage' if you can call it that.
My lap dog Yorkies will hopefully never consume such things...nor will they likely kill rats. Were they to come in contact with the toxic load one of today's city rats was carrying, if it didn't cause lethal or at least serious harm, I would be absolutely shocked because today's food makes me ill just from the chemical additives! |