"Broken heart" symbol on dogs?

[hekele]

Broken heart or lightning heart. Not sure. What does this mean? I have it on three dogs right now - a young male, an old male and an old female, all of whome seem to have fine stats. Nothing is unusually low. It's probably 5 seasons with dogs and I haven't seen this before.

[Maehlice]

It's a random disease. It's basically a DoT you can't do anything about. Just let it run its course and hope the critters don't die. It can happen at random to any group of domestic animals.

[Ronald Gordo]

If other animals get sick, be sure to raise the levels (even above the limit of available stables). This will prevent villagers from killing adult animals (to keep the limit) while others die of the disease (which could reduce the herd severely).
Remember to tame some puppies of the sick species (this makes up for some deaths).

[dakinidream]

Sure, diseases, that's normal in a way.
But i think there lot of diseases, and few puppies from the dogs. Had several couples, so we could exept having lot puppies. I mean i had puppies in rl, they make lot mostly.
But here i have still to tame some again and again.

It's ok some get killed i mean by raiders, or diseases, just i would wish more puppies, what would make it more enjoyable to raise the dogs.