This week we learned that Noah has hypothryoidism. His thyroid gland isn't producing enough hormone for his body.
Masticatory Muscle Myositis (MMM), a blood test showed that Samba had a low thyroid reading. We started treatment, but we're pretty sure that her facial paralysis was probably related to the thyroid problem. We've had to adjust her dosage upwards, but now seem to have it at a perfect level for her.
Some of the common symptoms of thyroid disease in dogs is weight gain, lower activity level, lethargy, mood swings, cold intolerance, hair loss or changes in coat becoming dry, dull, brittle.
There are many others and if left untreated this can shorten your dog's life span. Treatment can be as easy as giving a tablet twice a day. The medication is inexpensive, works quickly and you can actually see the changes.
If you're interested in reading more or in checking out the other symptoms, this is an excellent article by one of the authorities on the subject.