Yes I believe it is I have a chihuahua mix and this just started with her. She can’t sit or walk and same- doesn’t want treats or to eat. From the pain. From the way your pup sat down I think it could be in her left knee. That’s how my dog sits with the leg leg lazy like that. Small dogs the patella rotates inward usually. What I did for my dog (didn’t take her to a vet) I would lay her on her side and then ten minutes each leg 😞 I massaged the muscle first to loosen it up then I massaged the knee joint. I looked online at X-ray pix of femur tibia of a small dog and tried to find the knee joint and then on the insides of her at that spot, I would gently but semi firmly rub (like a lymphatic massage on your face) in the direction of the front of the knee to try and promote the patellar ligament to side back over the front of the knee joint and not twist around the leg. I guess this happens from genetic defeats in chihuahuas where the legs twist outward or bow outward. Your dog is really cute and I can tell is a people pleaser in her sweet face. I pray she can get some natural supplements for joint health and (I hate to say it but pain meds if needed) I hate medications… but if it’s THAT bad whrre she can’t even walk, I gave my dog Gabapentin and Rimadyl for pain and inflammation when it got REALLLLLLY bad. I also give her chlorella to removes toxins from the meds. Godspeed hope this helps
