Introduction

• Pituitary tumors can be classified as :
  • Non invasive adenomas, invasive adenomas Pituitary adenoma, or
  • Adenocarcinoma Adenoma / adenocarcinoma (in the presence of metastatic disease).
• A study looking at necropsy of dogs with pituitary tumors showed the following incidence:
  • 61% dogs with non invasive adenomas, 33% dogs with invasive adenomas, and 6% with carcinomas. 
• Another classification of micro (< 1cm) vs macro (>1 cm) tumors has been derived from human medicine but is controversial due to variability in dogs’ conformation and size. 
• Pituitary neoplasia can be silent (non functional) or secreting hormone (functional). 
• Pituitary tumor can arise from different cell types:
  • Corticotroph, somatotroph, thyrotroph (not reported in dogs), gonadotroph (not reported in dogs), lactotroph (one case report).  
• The most common pituitary tumor in dogs is the corticotroph adenoma, which can cause pituitary- dependent hypercortisolism by overproducing ACTH. 
• Signs: depend on tumor size (neurological signs such a obtundation, decreased appetite, seizures) and secretory properties (eg hypercorticism for ACTH producing tumors). 
• Metastatic tumors have also been reported to the pituitary. 
• Despite being benign, adenoma can still compress or invade neighboring tissues. 
• Diagnosis: CT or MRI of the head.  
• Treatment: options include surgery, radiotherapy.