Aloha! You're speaking to Dr. Michael Salkin
I'm sorry that your question wasn't answered in a timely manner. Both symptoms are danger signs but they're not pathognomonic (specifically indicative) of any one disorder. Tachypnea (breathing fast) can represent both medical and behavioral problems. It's often seen with elevated ambient temperature, exercise, anxiety, or perceived pain. To confound the diagnosis further, it's also seen with fever, narcotic administration, glucocorticoid (prednisone, e.g.) therapy, Cushing's disease (not at his age), hyperthyroidism (rare), hypocalcemia, pheocromocytoma (an adrenal gland tumor/rare), cardiac disease, tachyarrhythmias (fast irregular heart rates), brain
disease and obesity.
Drinking too much water (polydipsia) has many possible etiologies including urinary tract infection involving the kidneys, both renal and hepatic insufficiency, diabetes mellitus
and diabetes insipidus, Addison's disease, Cushing's disease (again, not at his age), and electrolyte (calcium, sodium, potassium) imbalances.
If he's been symptomatic in this manner for more than 3 days, his vet will need to thoroughly examine him and perform diagnostics in the form of blood and urine tests in an attempt to clarify what's going on with him. Please respond with further questions or concerns if you wish.