Welcome, Sammie, and sorry about losing Neko
Sounds like Sammie & Neko did everything together... has Sammie ever been an only dog in the past? if not, and she went from being in a litter to always having Neko, I'm guessing this is a huge adjustment for her. Also, if you don't mind sharing, what happened to Neko? was it a sudden and relatively quick thing? if so, that would be pretty hard for Sammie to deal with.
I got Worm when he was older for a puppy-- 4 months, instead of more often 2 months. Up until I got him, he spent every day of his life with at least 12-15 puppies and dogs. so huge shock when he became the only dog. it's one reason I didn't mind putting him in daycare (also necessary because of my work schedule), so he can be around lots and lots of dogs, like he'd been used to. and indeed, he plays very well w/other dogs and loves, loves to be around the other dogs. I also sought out some playgroups on Meetup.com. At first, couldn't find any basset groups, so he joined a Beagles playgroup and a Welsh Corgi playgroup (same body type!). Now we finally found other basset people and he has playgroups with them at the local dogparks and off-leash dog beaches in the area. Yeah, and I took him to dogparks, because at this age, he is so active and loves to socialize, run, be mouthy with, other dogs, especially other pups and teenagers like himself. Also when Worm got attacked, I increased the amount of playtime he had w/other dogs, since it was a stressful time for him. And I didn't want him to be afraid of other dogs. I wonder if Sammie would benefit from some of this too?
or if not comfortable with dogparks, then finding other dogs that Sammie gets along with and arrange some playdates for them...? like in someone's backyard or something...?
Re: ear infections, they can be internal so you can't always see anything different looking inside their ears. Also, sometimes they are just generally uncomfortable. When Worm had his ear infection, he was scratching globally, not just his ears. He would scratch his body too, tho it was the ear infections that were causing his discomfort. also, he only scratched one ear. imagine my surprise when they told me he has yeast infections in BOTH ears. meaning it's not always obvious from their behavior what's happening. I had never seen him scratch that other ear. Good to get it checked out by the vet, so they can confirm one way or the other.
Re: eye infections, Worm would get super gloppy, yellow stuff coming out of his eyes. Bassets are prone to dry eye and infections. and ya have to be careful because you don't want an infection brewing too long in the eye, since vision can be at stake. when his eyes looked infected, the vet gave us antibiotic eye ointment. since it still happens occasionally (like when we go to the beach and he gets grains of sand in his eyes), she told me to keep the tube and just use it when i see those symptoms again. also, for dry eye, we have an OTC eyedrops that our vet recommended. I give him those a couple times a week. he seems to find them soothing.
re: housetraining. Worm now uses a bell, so that helps. from what you've described, I would follow Sammie around like a hawk, especially when she comes inside and heads for the basement. (i do think that often dogs like to pee in the same area... Worm definitely has his fav spots. unfortunately, his favorite poo spot is in the parking garage [likes concrete] in parking spot 89. one day, it's going to be embarrassing when our neighbors in spot 89 see Worm going #2. so all that to say, it doesn't seem unusual that Sammie goes back to same spot).
Anyways, i found that one supereffective move in housetraining is to interrupt Sammie while she's going in the spot. As soon as she starts to pee or looks like she will pee, pick her up (usually they stop peeing when you've interrupted them) and take her outside to one of her favorite pee spots. We had to do this a couple times w/Worm, but he got the message quickly. Also, it works because usually the dog hasn't finished peeing and still has to go. And she finishes in the correct spot, and then she will get lots and lots of kisses and treats from you. The key to this is that you really do need to watch Sammie like a hawk or like you're watching a toddler-- know what she is up to every minute, and when you can't watch her, she is confined somewhere (ie. backyard, another room, crate)..
btw, please post some pics soon, Sammie!
--your pal, Worm