Zinc Poisoning and Lockjaw

[Geese are my Therapy]

One of our geese, a Pomeranian, was diagnosed with chronic heavy metal zinc poisoning about a month ago. They also noticed while treating him for the zinc that he had developed lockjaw and wasn't able to open his beak but 0.5 cm. They tried steroids in case it was autoimmune based, since they said that wouldn't be a result of the zinc, but it didn't really do anything. After his two week stay, the zinc was out of his blood and he was able to open his mouth 2.5 cm, still way below normal. Today we brought him for his one month checkup to retest his blood and because he still wasn't opening his mouth properly which has been effecting how much he eats and his preening capabilities. We're awaiting the results, but we removed the galvanized steel food buckets that he'd apparently been teething on so hopefully the zinc test is negative. However, all of our birds, 27 of them!, are housed within a 20 x 20 dog cage with roofing panels. There's a possibility the galvanized material is leaching into the water when it rains and he's then playing and ingesting the water/zinc that way. We can't really redo a new structure so I don't know what the outcome will be if he does have more in his system.
But more concerning is the lockjaw issue, especially since the vet doesn't really have a cause for it and therefore no treatment for it to get better.
Has anyone ever encountered lockjaw in one of their birds?

 

[ellie62706]

That's never happened to me, it sounds terrible!!
If you were to put a tarp over their home when it rains or snows, you might be able to stop the water carrying zinc, I definitely think it's important to find a new enclosure.

 

[Miss Lydia]

Doesn't lock jaw usually happen with wounds of some kind?