ISSN 2398-2969      

Pituitary adenoma



  • Estimates of incidence of brain neoplasia vary from 2-3% of dogs to 15 in 100,000.
  • Pituitary adenomas are a common brain neoplasm. They account for approximately 13% of all intracranial tumours in dogs.
  • They may be non-functional, or cause endocrine disorders.
  • The possible endocrine disorders associated with pituitary adenoma include pituitary-dependent hyperadrenocorticism (hypersecretion of ACTH), diabetes insipidus or acromegaly.
  • The most common type in dogs is corticotroph adenoma (hypersecretion of ACTH). 
  • Signs: neurological signs, where present, include:
    • Pacing.
    • Lethargy.
    • Wandering.
    • Head-pressing.
    • Hiding.
    • Tight circling.
    • Trembling.
    • Seizures.
    • Blindness.
    • Positional nystagmus.
    • Symmetric tetraparesis.
    • Anorexia.
  • Diagnosis: signs, laboratory tests, MRI, CT scan.
  • Treatment: pituitary ablation (surgical, radiotherapy).
  • Prognosis: guarded but depends on size.



  • Various tumor types.
  • Chromophobe adenomas, adenocarcinomas and acidophil adenomas.
  • Most adenomas associated with hyperadrenocorticism are too small to produce neurological signs.
  • It is believed that pituitary corticotroph tumors result from somatic mutations that occur within the corticotroph cells (rather than by chronic stimulation from hypothalamic factors).

Predisposing factors


  • Presently unknown.


  • 30% or more are larger and may become invasive, producing neurological signs due to local compression.
  • Occasionally, tumors cause hypopituitarism by mechanical or functional impairment of remaining pituitary tissue.
  • Non-functional pituitary tumors cause neurological signs or hypopituitarism through compression of pituitary and brain tissue during expansion and through peritumor edema.
  • Functional pituitary tumors have similar effects on pituitary and brain tissue, but also cause endocrine disorders through excessive hormone secretion (most common is pituitary-dependent hyperadrenocorticism (PDH)).
  • Central diabetes insipidus is sometimes caused by interference with the synthesis of antidiuretic hormone in the supraoptic nucleus, or its release into the pars nervosa.


  • The course is usually insidious and slowly progressive over many months up to 4-6 years in some dogs with pituitary-dependent hyperadrenocorticism.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Sanders K, Galac S, Meij B P (2021) Pituitary tumour types in dogs and cat. Vet J 270, 105623 PubMed
  • Del Magno S, Fracassi F, Grinwis G C M, Mandrioli L, Gandini G, Rossi F, Sirri R, Pisoni L, Tryfonidou M A, Meij B P (2019) Sequential Treatment of a Large Pituitary Corticotroph Neoplasm and Associated Neurological Signs in a Dog. J Am Anim Hosp Assoc 55 (2), e552-02 PubMed
  • Hansen K S,  Zwingenberger A L, Théon A P, Kent M S (2019) Long‐term survival with stereotactic radiotherapy for imaging‐diagnosed pituitary tumors in dogs. Vet Rad 60 (2), 219-232 PubMed.  
  • Menchetti M, De Risio L, Galli G, Cherubini G B,Corlazzoli D (2019) Neurological abnormalities in 97 dogs with detectable pituitary masses. Vet Q 39 (1), 57-64 PubMed.  
  • Miller M A, Bruyette D S, Scott-Moncrieff J C et al (2018) Histopathologic Findings in Canine Pituitary Glands. Vet Path 55 (6), 871-879 PubMed.  
  • Miller M A, Owen T J, Bruyette D S, Scott-Moncrieff J C, Ramos-Vara J A et al (2018) Immunohistochemical Evaluation of Canine Pituitary Adenomas Obtained by Transsphenoida l Hypophysectomy. Vet Path 55 (6), 889-895 PubMed
  • Sawadaa H, Mori A, Lee P, Sugihara S, Oda H, Sako T (2018) Pituitary size alteration and adverse effects of radiation therapy performed in 9 dogs with pituitary-dependent hypercortisolism. Res Vet Science 118,19-26 PubMed
  • Vastenhout N,van Rijn S J, Riemers F M, Tryfonidou M A, Meij B P, Penning L C (2018) The mRNA expression of PTTG1 is a strong prognostic indicator for recurrence after hypophysectomy in dogs with corticotroph pituitary adenomas. Vet J 240, 19-21 PubMed.  
  • Ben-Shlomo A, Cooper O (2017) The role of tyrosine kinase inhibitors in the treatment of pituitary tumors: from bench to bedside. Curr Opin Endocrinol Diabetes Obes 24(4), 301-305 PubMed.
  • Nagata N, Kojima K, Yuki M (2017) Comparison of Survival Times for Dogs with Pituitary‐Dependent Hyperadrenocorticism in a Primary‐Care Hospital: Treated with Trilostane versus Untreated. J Vet Intern Med 31 (1), 22-28 PubMed
  • Sato A, Teshima T, Ishino H, Harada Y, Yogo T, Kanno N, Hasegawa D, Hara Y (2016) A magnetic resonance imaging‐based classification system for indication of trans‐sphenoidal hypophysectomy in canine pituitary‐dependent hypercortisolism. J Small Anim Pract 57(5), 240-246 PubMed.  
  • Fracassi F,  Corradini S, Floriano D, Boari A, Aste G, Pietra M, Bergamini P F, Dondi F (2015) Prognostic factors for survival in dogs with pituitary‐dependent hypercortisolism treated with  trilostane. Vet Rec 176 (2), 49-49 PubMed
  • Marcinowska A, Warland J, Brearley M, Dobson J (2015) Comparison of two coarse fractionated radiation protocols for the management of canine pituitary macrotumor: an observational study of 24 dogs. Vet Radiol Ultrasound 56(5), 554-562 PubMed.
  • Fracassi F, Mandrioli L, Shehdula D, Diana A, Grinwis G C M, Meij B P (2014) Complete Surgical Removal of a Very Enlarged Pituitary Corticotroph Adenoma in a Dog. J Am Anim Hosp Assoc 50 (3), 192-197 PubMed
  • Mamelak A N,  Owen T J, Bruyette D (2014) Transsphenoidal surgery using a high definition video telescope for pituitary adenomas in dogs with pituitary dependent hypercortisolism: Methods and results. Vet Surg 43 (4),369-379 PubMed.
  • van Rijn S J,  Galac S, Tryfonidou M A,  Hesselink J W, Penning L C, Kooistra H S, Meij B P (2014) The Influence of Pituitary Size on Outcome After Transsphenoidal Hypophysectomy in a Large Cohort of Dogs with Pituitary‐Dependent Hypercortisolism. J Vet Int Med 30 (4), 989-995 PubMed.
  •  Fukuoka H, Cooper O, Ben-Shlomo A, Mamelak A, Ren S G, Bruyette D, Melmed S (2011) EGFR as a therapeutic target for human, canine, and mouse ACTH-secreting pituitary adenomas. J Clin Invest 121(12), 4712-4721 PubMed
  • Auriemma E, Barthez P Y, van der Vlugt-Meijer R H, Voorhout G, Meij B P (2009) Computed tomography and low-field magnetic resonance imaging of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism: 11 cases (2001-2003). JAVMA 235 (4), P 409-414 PubMed.
  • Dow S W, LeCouteur R A, Rosychuk R A W, Powers B E, Kemppainen R J, Gillette E L (2009) Response of dogs with functional pituitary macroadenomas and macrocarcinomas to radiation. J Small Anim Pract 31 (6), 287-294.  
  • de Fornel P, Delisle F, Devauchelle P, Rosenberg D (2007) Effects of radiotherapy on pituitary corticotroph macrotumors in dogs: A retrospective study of 12 cases. Can Vet J 48(5),481-486 PubMed
  • Hanson J M, Teske E, Voorhout G, Galac S, Kooistra H S, Meij B P (2007) Prognostic factors for outcome after transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism. J Neurosurg 107(4), 830-840  PubMed
  • Kent M S, Bommarito D, Feldman E, Theon A P (2007) Survival, Neurologic Response, and Prognostic Factors in Dogs with Pituitary Masses Treated with Radiation Therapy and Untreated Dogs. J Vet Intern Med 21 (5), 1027-1033 PubMed.   
  • Hanson J M, van‘t Hoofd M M,Voorhout G,Teske E, Kooistra H S, Meij B P (2005) Efficacy of Transsphenoidal Hypophysectomy in Treatment of Dogs with Pituitary‐Dependent Hyperadrenocorticism. J Vet Intern Med 19 (5),687-694 PubMed.
  • Ishinoa H, Haraa Y, Takekoshib S, Teshimac T, Teramotod A, Osamurab R Y, Tagawaa M (2001) Ki-67 and minichromosome maintenance-7 (MCM7) expression in canine pituitary corticotroph adenomas. Domestic Animal Endocrinology 41 (4),207-213 PubMed.
  • Greco D S et al (1999) Concurrent pituitary and adrenal tumors in dogs with hyperadrenocorticism - 17 cases (1978-1995). JAVMA 214 (9), 1349-1353 PubMed.
  • Goossens M M C et al (1998) Efficacy of Cobalt 60 radiotherapy in dogs with pituitary-dependent hyperadrenocorticism. JAVMA 212 (3), 374-376 PubMed.
  • Meij B P et al (1998) Results of transsphenoidal hypophysectomy in 52 dogs with pituitary-dependent hyperadrenocorticism. Vet Surg 27 (3), 246-261 PubMed.
  • Bertoy E H et al (1996) One-year follow-up evaluation of magnetic resonance imaging of the brain in dogs with pituitary-dependent hyperadrenocorticism. JAVMA 208 (8), 1268-1273 PubMed.

Other Sources of Information

  • Lunn K L, Boston S E (2020) Cancer chemotherapy. In: Small Animal Clinical Oncology. 6th edn. Eds Withrow & MacEwen. Elsevier Saunders, St. Louis. pp 565-56.
  • Moore S A, O’Brien D P (2008) Canine pituitary macrotumours. Compendium pp 33-41. 

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