Not alone at all!
PSSM isn't that bad. It isn't great either, but in the scheme of problems our horses may have it isn't a life ruiner. Before Baby Girl's major attack, she was an endurance horse in the works. We had just moved up from 35s to 50/60 mile weekends. Baby Girl could somehow manage 35s with (unknown, untreated) PSSM, but conditioning for and doing 50s was too much. She started coming out stiff, having metabolic issues, lameness, and all those other signs. I noticed muscle wasting, mistook for it simple thinness, and increased her grain. The increased grain was the final straw before she tied up during a routine training ride.
She was out for four months recovering and getting her diet straight. I noticed subtle changes in her movement after one month, and the changes became more noticeable in two months. I mostly saw changes in her walk. It was swingy and free. She used her butt. Eventually, I noticed her trot freeing up. Her exercise tolerance increased. So much energy! She could manage conditioning rides without grumpiness and exhaustion. Three months and she was beginning to canter (badly) at liberty. She was gaiting like a proper gaited horse. Every month, her movement just got more swingy. It's almost something you have to see to describe. A year later, I can finally say she has a balanced, ground covering trot.
As far as limitations go... I haven't found any yet. Baby Girl is better than she ever was. She blazed through one moderate 50 and one uber tough 50 winter of 2012 like a machine. We're fully booked for 2013. Hoping to win a national championship.
Sometimes horses have rough days. Sometimes Baby Girl is grumpy and doesn't want to talk to me either!
I hope Snickers improves too! Most PSSM horses respond excellently to the diet. BG has actually never been tested for PSSM; she was diagnosted via outward signs and response to treatment. My vet said it would be a waste of money to send off hair or biopsy with results like that.
(Baby Girl probably has type 2 anyway, which doesn't show up on a genetic test. She's a SSH; not a normal breed to be affected.)
That's the same info that got me started on my diet journey. Dr. V is wonderful and helped me a lot.