@phonehouse So there's a lot of room between 2yo and 10yo, right? My parents got a Jack Russell Terrier--also not recommended for small children--when I was 4yo and my sister was 2yo. It actually worked really well, probably because the first one came from a breeder who was deliberately breeding for a "softer" pet dog that
would be very good with families and children. (He was: this was a dog who was as predatory as any other JRT I've known, but was so gentle with children that he refused to pull on the leash if a small child was holding the other end.) They loved him so much they got another one, from a breeder who met more responsible breeder metrics but whose breeding program was structured around vermin work, when I was seven. Great dogs. Love them myself, too.
...
but...
...they were pretty stressful for my parents, especially with the second dog. She also loved children and was surprisingly tolerant,
but she saw kids and launched herself at them with her whole body to lick their faces, and she made quite a few visitors to the house fall down and cry. And the dog from the "responsible" breeder that wasn't focused on good pet temperament was
much harder. She got bored and learned to be an escape artist, which didn't improve the headache situation.
...they had two adults to assist with supervision and enrichment; I don't know how much your ex is plugged into coparenting, but if you're a full-time single mom things are obviously going to continue to be difficult.
...because the Jack Russells were small, it was much harder for one of them to carelessly knock a child older than a larger heeler. It was also harder for one of them to hurt us by accident, even if they were excited in play.
...it was important to make sure the dogs never saw the kids as toys or things to chase for bitey purposes, and it was very important to prevent mouthiness. JRTs are not quite as bitey-focused as baby cattle dogs, in my experience.
...my parents took pains to prevent us small children bothering or annoying the dogs as much as humanly possible lest the dogs object.
I have a year-old heeler pup myself. I would not personally trust her unrestrained around a toddler, because she does not have great body awareness and she has the same tendency to dive for face licks as my childhood JRT did. In six months to a year, sure, I think she could do that--and I've discussed having kids in the near future with my partner with that exact thing in mind. I don't think she'd have any problem at all with a little more impulse control under her belt.
The trick is that a heeler
puppy is a lot of dog, and so is an untrained adolescent heeler. Toddlers are relatively bitty! And of course heelers with a lot of self regulation are pretty uncommon in rescue. If I really wanted one, I would
either look for a middle aged or older dog to adopt which is a bit more sedentary inside the house,
or I would wait for at least two years so that your son can get a little bit bigger and resilient first. Or both!