ISSN 2398-2950      



Synonym(s): Growth hormone excess, hypersomatotropism


  • Historically considered relatively rare endocrine disease.
  • Recognized with increasing frequency in recent years - estimated prevalence of 25% in cats with diabetes mellitus in the UK.
  • Hypersomatotropism = condition of excessive growth hormone (GH) secretion. 
  • Acromegaly = clinical syndrome resulting from subsequent chronic overgrowth of connective tissue, bone and viscera.
  • Cause: persistent excessive growth hormone (GH) secretion from pituitary adenoma Pituitary gland: neoplasia.
  • Signs:
    • May be mild glucose intolerance or overt diabetes mellitus.
    • Insulin-resistant diabetes mellitus Diabetes mellitus (in some cases can be controlled by increasing insulin dose).
    • Cardiomyopathy Heart: hypertrophic cardiomyopathy; systolic murmur; gallop rhythm.
    • Chronic heart failure Heart: congestive heart failure; pleural effusion, pulmonary edema Lung: pulmonary edema.
    • Polyphagia, sometimes dramatic, with weight gain or weight loss.
    • Neurological signs, particularly obtundation, behavior change, gait abnormalities.
  • Prognosis: survival time 8-30 months. Most die of complications, eg congestive heart failure Heart: congestive heart failure, renal failure Kidney: chronic kidney disease, neurological signs, or euthanazed due to painful polyarthropathy.
    Print off the owner factsheet Acromegaly in cats to give to your client.




  • GH is synthesized in the pars distalis of pituitary gland.
  • Release is episodic and is controlled by growth hormone releasing hormone (GHrH) and inhibited by somatostatin.
  • The anabolic effect of GH, ie soft tissue and skeletal growth and protein synthesis are mediated by insulin-growth factor (IGF-1).
  • The catabolic effects, eg lipolysis and reduced cellular glucose transport are direct effects of GH.
  • Increased GH concentrations causes a reduction in the number of insulin receptors, reduced binding affinity and a post-receptor defect.
  • More insulin has to be produced to overcome these effects but hyperinsulinemia leads to further down regulation of receptors and ultimately DM.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Miceli D D, Garcia J D, Pompili G A et al (2022) Cabergoline Treatment in Cats with Diabetes Mellitus and Hypersomatotropism. J Feline Med Surg PubMed doi:10.1177/1098612X221074924
  • Watson-Skaggs M L, Gieger T L, Yoshikawa H et al (2022) Endocrine Response and Outcome in 14 Cats with Insulin Resistance and Acromegaly Treated with Stereotactic Radiosurgery (17 Gy). Am J Vet Res 1-8 PubMed doi: 10.2460/ajvr.21.08.0122.
  • Scudder C J, Hazuchova K, Gostelow R et al (2021) Pilot Study Assessing the Use of Cabergoline for the Treatment of Cats with Hypersomatotropism and Diabetes Mellitus. J Feline Med Surg 23, 131-137 PubMed doi: 10.1177/1098612X20933213.
  • van Bokhorst K L, Galac S, Kooistra H S et al (2021) Evaluation of Hypophysectomy for Treatment of Hypersomatotropism in 25 Cats. JVIM 35, 834-842 PubMed doi:10.1111/jvim.16047
  • Fenn J, Kenny P J, Scudder C J et al (2021) Efficacy of Hypophysectomy for the Treatment of Hypersomatotropism-Induced Diabetes Mellitus in 68 Cats. JVIM 35, 823-833 PubMed doi: 10.1111/jvim.16080.
  • Wormhoudt T L, Boss M K, Lunn K et al (2018) Stereotactic Radiation Therapy for the Treatment of Functional Pituitary Adenomas Associated with Feline Acromegaly. JVIM 32,1383-1391 PubMed doi: 10.1111/jvim.15212.
  • Gostelow R, Scudder C, Keyte S et al (2017) Pasireotide Long-Acting Release Treatment for Diabetic Cats with Underlying Hypersomatotropism. JVIM 31(2), 355-364  PubMed doi10.1111/jvim.14662.
  • Niessen S J, Forcada Y, Mantis P et al (2015) Studying Cat (Felis Catus) Diabetes: Beware of the Acromegalic Imposter. PloS One 10, e0127794 PubMed
  • Niessen S J (2010) Feline acromegaly, an essential differential diagnosis for the difficult diabetic. J Feline Med Surg 12 (1), 15-23 PubMed doi: 10.1371/journal.pone.0127794.
  • Dunning M D, Lowrie C S, Bexfield N H et al (2009) Exogenous insulin treatment after hypofractionated radiotherapy in cats with diabetes mellitus and acromegaly. JVIM 23 (2), 243-249 PubMed.
  • Berg R I, Nelson R W, Feldman E C et al (2007) Serum insulin-like growth factor-1 concentration in cats with diabetes mellitus and acromegaly. JVIM 21 (5), 892-898 PubMed.
  • Niessen S J, Petrie G, Gaudiano M et al (2007) Feline acromegaly: an underdiagnosed endocrinopathy? JVIM 21 (5), 889-905 PubMed.
  • Niessen S J, Khalid M, Petrie G et al (2007) Validation and application of a radioimmunoassay for ovine growth hormone in the diagnosis of acromegaly in cats. Vet Rec 160 (26), 902-907 PubMed.
  • Brearley M J, Polton G A, Littler R M et al (2006) Coarse fractionated radiation therapy for pituitary tumours in cats: a retrospective study of 12 cases. Vet Comp Oncol 4 (4), 209-217 PubMed.
  • Mayer M N, Greco D S, LaRue S M (2006) Outcomes of pituitary irradiation in cats. JVIM 20 (5), 1151-1154 PubMed.
  • Starkey S R, Tan K, Church D B (2004) Investigation of IGF-1 levels amongst diabetes and non-diabetic cats. J Feline Med Surg (3), 149-155 PubMed.
  • Elliot D A, Feldman E C, Koblik P D et al (2000) Prevalence of pituitary tumors among diabetic cats with insulin resistance. JAVMA 216 (11), 1765-1768 PubMed.
  • Feldman E C & Nelson R W (2000) Acromegaly and hyperadrenocorticism in cats - a clinical perspective. J Feline Med Surg (3), 153-158 PubMed.
  • Norman E J & Mooney C T (2000) Diagnosis and management of diabetes mellitus in five cats with somatotrophic abnormalities. J Feline Med Surg (4), 183-190 PubMed.
  • Goossens M M, Feldman E C, Nelson R W et al (1998) Cobalt 60 irradiation of pituitary gland tumors in three cats with acromegaly. JAVMA 213 (3), 374-376 PubMed.
  • Merchant S R, Taboada J (1995) Systemic diseases with cutaneous manifestations. Vet Clin North Am Small Anim Pract 25 (4), 945-959 PubMed.
  • Peterson M E, Taylor R S, Greco D S et al (1990) Acromegaly in 14 cats. JVIM (4), 192-201 PubMed.
  • Morrison S A, Randolph J, & Lothrop C D Jr. (1989) Hypersomatotropism and insulin resistant diabetes mellitus in a cat. JAVMA 194 (1), 91-94 PubMed.
  • Wolf A M (1989) Feline endocrinology. Tijdschr Diergeneeskd 114 (Suppl 1), 15S-18S PubMed.

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