I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. My name is XXXXX XXXXX I'm a biologist with a special interest in reptiles. I'm sorry to hear of this problem.
Fatty has probably been sick throughout his hibernation. Because he lost fluids while traveling, he was not in condition to hibernate. Hibernation is always a risky time for tortoises, but for on one less than optimal condition, it is downright dangerous. He is exhibiting symptoms of a respiratory infection. while this may sound similar to a human cold, in a tortoise, it is quite serious. It can be very difficult to clear up if not treated promptly. He needs to be seen by a reptile vet as soon as possible. Otherwise, he is likely to develop what is referred to as "Runny Nose Syndrome (RNS)." It is a chronic RI or pneumonia. It often requires repeated treatment. He may already have pneumonia, which will require aggressive treatment. The milky eyes can be a symptom of a respiratory infection, too, or they may be the result of a separate eye infection or a vitamin A deficiency. You can read more about RNS here:http://www.tortoisetrust.org/articles/commondisease.html#Respiratory
In the meantime, you can help Fatty by increasing the temperature for him. You should have a basking light, which can be any sort of fixture that will take an ordinary incandescent bulb. Choose one with the proper strength (watts) to keep the area directly under it at 90*F in the daytime. The coolest part of the habitat should be 70*F. That gives the tortoise a range of temperatures to choose from. Because of the new climate, Fatty may need different care than he did when living in the desert. He may need to be indoors more often and will need supplemental heat. If you would like to read more about desert tortoise care, here is a reputable website:http://www.tortoise.org/general/descare.html
What's most immediately important is to get him to a vet. Here are links to directories of reptile vets:http://www.austinsturtlepage.com/Info/state_resources.htm
If you have more questions, let me know in a REPLY. I hope Fatty will reach a full recovery.
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