Use this cаse study tо аnswer the fоllоwing questions: A Shetlаnd Sheepdog named Tubby has come to the clinic for a routine exam with vaccines. Tubby is 10 years old and the owners have noticed that he isn’t energetic anymore. On P/E, Tubby is overweight by about 15pounds and has a rough, coarse hair coat. There’s hair loss at thebase of his tail, creating a “rat tail” appearance. The owners have noticed that Tubby has been eating more than usual. Dr. Lovett decides to order lab work to measure T4 levels. When the lab results return the following day, the T4 levels are decreased in the blood. What is Tubby's diagnosis?