Perhaps I can give you a little more information on this subject, since the list of treatments and symptoms above is for people and not dogs.
Most pituitary tumors are very small, and if they stay that way, they are unlikely to cause problems. When pituitary tumors do become problems is when they become macroadenomas. That simply means that the tumors grow large enough that they become a problem simply by the amount of space they take up.
Pituitary tumors are almost never cancerous. They are divided into two groups however, functioning and nonfunctioning. Functioning tumors produce one of the hormones produced in the endocrine system. The most common kind of functioning tumor produces cortisol. The extra cortisol in the body results in a disease called Cushings Disease. Another type of functioning tumor produces growth hormone. The excess amount in the body causes a disease called Acromegaly.
Nonfunctioning tumors cause different types of problems. The large macroadenoma pressing up against the pituitary gland starts to interfere with it's functioning. Usually thyroid function is affected first. The pituitary sends chemical signals to regulate the thyroid, when the thyroid stops receiving these, it slows down and hypothyroidism occurs. The pituitary stops regulating growth hormone, which is used during the adult years to help regulate muscle mass and insulin use. Fertility is decreased by the pituitary no longer regulating the sex organs to produce testosterone or estrogen. Energy drops due to a lack of cortisol being produced by the adrenal glands. This substance is needed by the body to fight illness and react to stress and emergencies. Finally, in cases with an extremely large macroadenoma, the part of the pituitary gland that regulates thirst and water retention will stop functioning.
The symptoms vary depending what type of pituitary tumor your dog has, and it's size.
If the tumor is a functioning one and produces cortisol, your dog will have a condition called Cushing's disease. The symptoms of this are excessive drinking and urination, an excessive appetite, a pot-bellied appearance due to redistribution of body fat, muscle weakness, hair loss and skin infections, excessive panting and shortness of breath, muscle stiffness, and high blood pressure.
Agromegaly, a condition where the tumor produces growth hormone, is characterized by some unusual looking growth, not in normal proportion, and a resistance to insulin which usually leads to diabetes.
With nonfunctioning tumors, a low or nonfunctioning thyroid will result in lethargy/mental dullness, hair loss, weight gain,
dry coat/shedding, hyperpigmentation of the skin, cold intolerance, slow heart rate, high cholesterol and anemia.
A low or non-existent growth hormone level will lead to muscle wasting and the inability to convert food into muscle mass.
A loss in communication from the pituitary to the sex glands will result in stopping the production of testosterone or estrogen. This results in infertility, and while replacement of these hormones is possible, fertility can not be corrected.
The pituitary gland controls one part of the adrenal gland, the part that produces cortisol. Cortisol is necessary for normal functioning, plus more is needed during illness and times of stress.
Finally, the pituitary gland controls water regulation. If this part of the pituitary is damaged, your dog will exhibit excessive thirst and urination, to the point that her sleep will be interrupted by needing water every 30-60 minutes.
These are the symptoms of the various conditions caused by pituitary tumors. There are several levels to the question of how you treat a pituitary tumor. First is how the tumor itself can be treated, and second is how the conditions it created can be treated.
Unfortunately, unlike in humans, pituitary tumors can not be surgically removed in dogs because of their location. Radiation therapy is used, but it is not a cure. It's used to buy time, but in many cases it damages the dog's eyes or ears. The primary danger of a macroadenoma is that it will eventually just run out of space to grow.
Until this becomes a problem, the specific conditions that it causes are treated. There is medication for cushings disease and acromeglia. Dogs with nonproductive tumors get hormone replacement for the conditions they have. They are treated with a synthetic form of cortisol, such as prednisone, if they have adrenal insufficiency. They are treated with thyroid medication (levoxyl, sinthroid) if they have hypothyroidism. If they have diabetes insipidis, they are treated with DDAVP to regulate their water needs.
It's important to remember that many dogs develop macroadenomas that stop growing and do not present further problems. Also, these adenomas can grow to a point of causing a medical condition, but may not need further treatment; only treatment of the secondary illness may need to be treated.
As for the symptoms your dog has, the panting and breathing makes me think that she may have Cushing's disease as a result of a functioning tumor. I'm not sure what the quivering indicates. It could be something neurologic, or it could be the result of just not feeling well.
I assume you have seen your vet and he is the one who has suggested the possibility of a pituitary tumor. I would talk to him more about what your options are and what he suggests.
I hope this information was helpful. Please let me know if you have any other questions or I can clarify anything.
This is a link explaining pituitary tumors in dogs:
This is a link on Cushing's disease: