Acromegaly in cats is caused by a pituitary tumor secreting excess growth hormone, leading to progressive facial and paw enlargement alongside poorly controlled diabetes. It is underdiagnosed but should be suspected in any diabetic cat requiring escalating insulin doses without achieving glycemic control.
Last reviewed: June 2026
What Is Acromegaly in Cats?
Feline acromegaly is an endocrine disorder caused by a functional pituitary adenoma that secretes excessive growth hormone (GH). Unlike dogs, in which acromegaly is usually driven by progesterone-induced GH secretion from mammary tissue, cats with acromegaly almost universally have a pituitary tumor as the source. Excess GH stimulates production of insulin-like growth factor 1 (IGF-1) in the liver, which drives the characteristic soft tissue and bony changes.
As described in Ramsey's BSAVA Manual of Small Animal Endocrinology, acromegaly should be high on the differential list for any middle-aged to older neutered male cat presenting with poorly regulated diabetes mellitus requiring unusually high insulin doses.
Signs of Acromegaly in Cats
Signs develop over months to years and are often attributed to normal aging before the diagnosis is made.
Physical changes:
- Enlargement of the paws, jaw, and head — the face may take on a coarser, more blocky appearance
- Prognathism (lower jaw projecting beyond the upper)
- Increased interdental spacing as soft tissue grows around teeth
- Weight gain or maintenance despite active diabetes — unusual in diabetic cats, which typically lose weight
- Organomegaly: liver, kidneys, heart, and tongue may all enlarge
Metabolic signs:
- Persistently elevated blood glucose despite escalating insulin doses — insulin resistance from GH's anti-insulin effect is the hallmark
- Polydipsia and polyuria from uncontrolled diabetes
- Polyphagia — cats with acromegaly often eat voraciously
- Snoring or stertor if pharyngeal soft tissue enlarges
- Exercise intolerance or labored breathing if hypertrophic cardiomyopathy develops
Niessen et al., 2007, JVIM demonstrated that serum IGF-1 is a highly sensitive screening test, with the majority of acromegalic cats having markedly elevated concentrations compared to diabetic controls.
Diagnosis and Treatment
Diagnosis:
- Serum IGF-1 — markedly elevated in most acromegalic cats; preferred initial screening test
- Pituitary MRI or CT — required to visualize the adenoma and assess size
- Echocardiography — assesses cardiac enlargement and function
- As described in Ettinger's Textbook of Veterinary Internal Medicine, cats requiring insulin doses above 6–8 units per injection without glycemic control should be screened for acromegaly; the AAFP-AAHA Feline Life Stage Guidelines, 2021 also recommend endocrine screening for persistently difficult-to-regulate diabetic cats
Treatment:
- Stereotactic radiation therapy — most effective option where available; many cats achieve improved glycemic control
- Hypophysectomy — available at referral centers; can be curative in selected cases
- Medical management — no consistently effective drug option; supportive management of diabetes, cardiac disease, and hypertension extends quality of life
When to See a Vet
Call your vet today if:
- Your diabetic cat requires escalating insulin doses without achieving blood glucose control
- Your cat's face, head, or paws appear larger or coarser than they did a year ago
- Your cat is eating voraciously yet maintaining weight despite being diabetic
- You notice snoring or noisy breathing you have not observed before
Go to the ER immediately if:
- Your cat is breathing with effort, sitting with elbows out, or has pale, blue, or grey gums — possible cardiac emergency
- Your cat collapses or appears suddenly weak
- Your diabetic cat shows trembling, disorientation, or seizures after an insulin dose (hypoglycemia)
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Frequently Asked Questions
What is the earliest sign of acromegaly in cats? The most common early presentation is a diabetic cat that requires higher and higher insulin doses without achieving normal blood glucose levels. Physical changes to the face and paws develop gradually and are often missed until the disease is well established. Any diabetic cat with insulin resistance should be screened with a serum IGF-1 measurement.
Can acromegaly be cured in cats? Definitive treatment with stereotactic radiation or surgical hypophysectomy can reduce GH secretion and improve glycemic control in many cats, with some achieving partial or full diabetes remission. Cure is not guaranteed, and the pituitary tumor may regrow over time. Medical management alone does not address the tumor but can maintain quality of life.
How common is acromegaly in diabetic cats? Studies suggest acromegaly is present in approximately 25–35% of cats with insulin-resistant diabetes, making it significantly more common than previously recognized. Most affected cats are older neutered males, though females and younger cats can also be affected.
How much does diagnosing and treating feline acromegaly cost? A serum IGF-1 test costs approximately $80–150 at most reference laboratories. Pituitary MRI or CT adds $800–2,000 at a referral center. Stereotactic radiation therapy typically costs $5,000–8,000 for a full course. Ongoing diabetic management (insulin, monitoring, blood curves) adds $100–300 per month. Better glucose control achieved through treating acromegaly often reduces long-term insulin costs.
Is acromegaly painful for cats? Acromegaly itself is not typically painful — the physical changes develop slowly over months to years. However, poorly controlled diabetes causes discomfort, and cats with secondary congestive heart failure or hypertension may feel unwell. Quality of life is generally maintained with good management of secondary conditions.
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