Page 83 - Cote clinical veterinary advisor dogs and cats 4th

Acromegaly 19

hypertrophy, polyphagic cats, and cats with • Cats (and rare dogs with a pituitary tumor): • With hypophysectomy, hypocortisolemia,
unexplained inspiratory noise, among other removal of the pituitary tumor or inhibition and hypothyroidism; ongoing supplementa-
VetBooks.ir • Cats: intracranial imaging (CT or MRI) can • Dogs and cats: conservative treatment entails Recommended Monitoring Diseases and Disorders
of tumoral GH secretion
presentations due to GH excess.
tion for both is necessary postoperatively.
further increase the certainty of the diagnosis,
merely attending to the consequences of GH
although absence of a visible pituitary
treatment.
mass does not rule out the possibility of excess (including diabetes mellitus); this is • Serum IGF-1 should normalize with effective
suboptimal and above options yield better
acromegaly. clinical results and quality of life. • Diabetes mellitus should be monitored as
for any diabetic patient (p. 251).
Differential Diagnosis Acute General Treatment
Differentials for insulin antagonism/resistance: • Diabetic pets require treatment for the PROGNOSIS & OUTCOME
• Hyperadrenocorticism (p. 485) diabetes (p. 251).
• Infection • Dogs with diestrus-associated acromegaly • Cats and dogs: if inciting cause is eliminated
• Drugs (e.g., glucocorticoids, progestins) could be treated temporarily with agle- at an early stage, life span and quality of life
• Hyperthyroidism (cats, p. 503) pristone, a progesterone receptor blocker can be normalized.
• Hypothyroidism (dogs, p. 525) (10 mg/kg/month), pending neutering or • If acromegaly has been present for a long time,
• Chronic pancreatitis (cats, p. 740) cessation of (the effects of) progestogen some physical changes can cause significant
• Obesity (p. 700) treatment. morbidity (e.g., cardiac hypertrophy, narrowed
• Diabetes management problems with insulin • Cats presented in congestive heart failure airways, pancreatopathy/pancreatitis).
type, storage, or administration (p. 251) should be treated accordingly (p. 408). • Cats: myocardial changes are reversible with
Differential for physical examination changes hypophysectomy.
mimicking acromegaly: Chronic Treatment • Cats: diabetes mellitus resolves in 85% of
• Primary hypothyroidism (dogs, p. 525) • In cats, best results seen with hypophysectomy hypophysectomy-treated patients and 25%
Differentials for elevated IGF-1 (rare): ○ Diabetes mellitus resolves in 85% of of pasireotide-treated patients
• GH and IGF-1 concentrations may be acromegalic, diabetic cats after surgery.
elevated in hypothyroid dogs. Measurement ○ Availability is limited in the United States. PEARLS & CONSIDERATIONS
of total thyroxine (T 4 ), free T 4 , and canine • In cats, the somatostatin analog pasireotide
thyroid-stimulating hormone (cTSH) con- effectively inhibits GH secretion (short-acting Comments
centrations can be used to exclude primary form: 0.03 mg/kg q 12-24h; long-acting • Understanding of acromegaly/hypersomato-
hypothyroidism. formulation 8 mg/kg/month or lowest tropism in cats is rapidly changing; among
• IGF-1 can be elevated in diabetic cats without effective dose) humans, most acromegalic patients are not
acromegaly (<5% of cases) ○ Does not usually shrink tumor diabetic. Increasingly, nondiabetic cats are
Differentials for myocardial thickening: ○ Has been associated with diabetic remis- recognized as suffering from acromegaly.
• Hypertrophic cardiomyopathy (primary sion in 1 of 4 cases Clinicians are therefore encouraged to keep
HCM, p. 505) ○ Currently very expensive an open mind about the exact presentation
• Systemic hypertension (p. 501) • Rarely, cats are responsive to the cheaper of feline acromegaly.
alternative cabergoline (5-15 mcg/kg/day). • If a cat or dog is treated for its diabetes only,
Initial Database • Radiotherapy can shrink a pituitary tumor regular quality of life assessments should be
• Determine if diabetes mellitus is present and improve diabetic control. conducted, ideally using standardized assess-
(fasting blood glucose, urine glucose, fructos- ○ Efficacy and timing of effect are ment surveys (diabetes apps are available).
amine); if diabetes is known to be present but unpredictable. • Weight gain in the face of poorly controlled
uncontrolled, consider serial blood glucose ○ Multiple anesthetics episodes are necessary, diabetes mellitus is highly suggestive of
assessment and revisit management with and hormones never normalize. acromegaly.
owner, including appropriate insulin storage. • If the inciting cause is not removed, treat
• In nondiabetic and diabetic cases: serum the consequences as best as possible. Prevention
IGF-1 measurement ○ Treating diabetes mellitus in cats can be • In dogs, spaying and avoidance of exogenous
• Abdominal imaging may be normal or frustrating, eventually requiring high progestin administration
hepatomegaly and renomegaly may be seen. insulin dosages.
○ Quality of life of treated cats should be Technician Tips
Advanced or Confirmatory Testing monitored closely; appetite is not a good • Quality of life of diabetic, acromegalic cats
• In cats, intracranial imaging (CT or MRI) measure given the GH-driven polyphagia. can be improved by teaching the owners
of the pituitary gland can help establish to perform home blood glucose monitoring
whether the pituitary is enlarged or a mass Nutrition/Diet and by conducting regular quality of life
is present; absence of enlargement does not • Cats: if concurrently diabetic, use a low assessments.
exclude the disease. carbohydrate diet • A pet diabetes app is available for free
• Cats and dogs: GH can be measured, but download onto smartphones and tablets from
it is difficult to find a suitable laboratory Possible Complications Android (http://bit.ly/1q3jCV5) and iPhone
with a validated assay. • Cats: if treated with high insulin dosages, App stores (http://apple.co/203OoK2).
hypoglycemia can occur due to pulsatile
TREATMENT GH secretion by the pituitary tumor; SUGGESTED READINGS
monitoring of home blood glucose can Niessen SJM, et al: Hypersomatotropism, acromegaly,
Treatment Overview screen for overdose. Owners should be and hyperadrenocorticism and feline diabetes
• Treatment is ideally aimed at removing the instructed on how to deal with hypoglycemia mellitus. Vet Clin North Am Small Anim Pract
cause. effectively. 43:319-350, 2013.
• Dogs: cessation of progestogen administra- • Radiotherapy complications include damage AUTHOR: Stijn J.M. Niessen, DVM, PhD, DECVIM
tion or neutering to local tissues and hypopituitarism. EDITOR: Ellen N. Behrend, VMD, PhD, DACVIM

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