CONDITION
Acromegaly in Cats
Acromegaly is a condition in which the body produces too much growth hormone over a sustained period, typically due to a small tumour in the pituitary gland at the base of the brain. In cats, this excess hormone affects how tissues grow and how the body handles sugar, leading to a constellation of gradual changes that may not be obvious at first. Owners often notice that their cat seems larger or heavier than before, with a broader face, bigger paws, or a more prominent lower jaw. Many cats with acromegaly also develop diabetes that proves difficult to manage with insulin, or they may drink and urinate more than usual. The changes tend to unfold slowly, over months or years, and can be mistaken for normal ageing or weight gain. This page explores the signals that may prompt consideration of acromegaly, what is happening in the body to produce those changes, how the condition is investigated through blood tests and imaging, and the range of approaches that exist once a picture becomes clearer.
Why this matters now
Acromegaly tends to appear in middle-aged to older cats, most often between eight and fourteen years of age. Male cats appear to be affected more frequently than females, though the condition can occur in either sex. There is no strong breed predisposition; cases have been documented across domestic shorthairs, longhairs, and pedigree breeds alike.
The condition typically unfolds over months to years, with changes accumulating so gradually that they may be mistaken for normal ageing or weight gain. Some cats develop signs of diabetes early in the course, while in others the physical changes become noticeable first. The rate of progression varies considerably between individuals, and the pattern of signs reflects both the level of growth hormone in circulation and how long it has been elevated.
Signals & patterns
Early signals
Increased thirst and urination
Many cats begin drinking more water than usual and producing larger volumes of urine. This often reflects the development of diabetes, which can occur when excess growth hormone interferes with the body's ability to use insulin effectively.
Weight gain despite appetite control
Owners may notice their cat becoming heavier or appearing bulkier, even when food intake has not changed significantly. The weight gain tends to be gradual and can be mistaken for overfeeding or reduced activity.
Subtle broadening of the face
The cat's face may appear wider or coarser over time, with a more prominent forehead or fuller cheeks. These changes are often only apparent when comparing recent photographs to those from a year or two earlier.
Increased insulin requirement
In cats already being treated for diabetes, the dose of insulin needed to control blood sugar may begin to climb steadily. This insulin resistance can be an early clue that something beyond straightforward diabetes is present.
Later signals
Enlarged paws and jaw prominence
The paws may appear larger, and the lower jaw can become more prominent or protrude slightly, sometimes causing a gap between the upper and lower teeth. These skeletal changes reflect sustained growth of bone and cartilage.
Laboured or noisy breathing
Overgrowth of soft tissues in the throat and airways can lead to snoring, snorting, or more effortful breathing, particularly during sleep or after exertion. In some cases, the tongue may appear thickened.
Heart murmur or exercise intolerance
The heart muscle can thicken over time, and some cats develop a detectable murmur or show reduced stamina during normal activity. These changes reflect the long-term effects of growth hormone on cardiac tissue.
Click to read about the biological mechanisms
How this is usually investigated
Investigation typically begins with a detailed history of changes over time, particularly around physical appearance, drinking behaviour, and any difficulty managing diabetes. Physical examination may reveal characteristic features such as a broad face, enlarged paws, or a protruding lower jaw. Blood tests and imaging follow, aiming to measure growth hormone or its downstream effects and to locate the source of excess production.
Blood biochemistry and glucose measurement
Insulin-like growth factor-1 measurement
Advanced imaging of the pituitary gland
Physical examination over time
Options & trade-offs
Management is typically individualised, balancing the control of growth hormone excess, the treatment of concurrent diabetes, and the monitoring of organ changes over time. Different combinations suit different cats and households, depending on the severity of signs, the presence of complications, and what is practical in a given setting. No single approach addresses all aspects of the condition, and many cats receive a combination of strategies adjusted as the picture evolves.
Radiation therapy directed at the pituitary tumour
Targeted radiation aims to reduce the size and activity of the pituitary mass, lowering growth hormone production over weeks to months. Treatment is typically delivered in fractionated doses under general anaesthesia at a specialist centre. Some cats experience a gradual reduction in insulin requirements and stabilisation or reversal of physical changes.
Trade-offs: Response is variable; some cats show marked improvement, while others see only modest benefit or none at all. The procedure requires repeated anaesthesia, access to specialist facilities, and monitoring for potential effects on surrounding brain tissue, and it may take months to assess the degree of response.
Medical management of growth hormone secretion
Drugs that suppress growth hormone release or block its action can be administered, typically by injection. Pasireotide, a somatostatin analogue, is used in some cases to reduce growth hormone secretion from the pituitary tumour. The effect on glucose control and physical signs varies between individuals.
Trade-offs: Availability is limited, and response can be unpredictable; some cats experience improved glucose regulation, while others show little change. Ongoing injections are needed, and the cost and practical demands may not suit every household.
Insulin therapy for concurrent diabetes
Many cats with acromegaly require insulin to manage persistently elevated blood glucose. Doses are often higher than in diabetic cats without acromegaly due to insulin resistance, and adjustments may be needed frequently. Blood glucose monitoring at home or through periodic clinic visits helps guide dose changes.
Trade-offs: Insulin addresses the glucose problem but does not reduce growth hormone levels or halt the progression of physical changes. Some cats remain difficult to stabilise even with high doses, and hypoglycaemia becomes a risk if insulin sensitivity changes unexpectedly.
Monitoring and supportive care
Regular assessment of body weight, glucose control, blood pressure, and organ function allows changes to be tracked and complications addressed as they arise. Adjustments to diet, fluid intake support, and management of secondary conditions such as heart or kidney changes can be made in response to findings. This approach may be chosen when other interventions are not feasible or when the condition is progressing slowly.
Trade-offs: Growth hormone excess continues unchecked, and physical and metabolic changes may progress over time. This path can provide a reasonable quality of life for some cats, particularly those with mild signs or advanced age, but it does not alter the underlying cause.
Common misconceptions
"Acromegaly only affects large or overweight cats."
While many cats with acromegaly do gain weight or appear larger, the condition is defined by excess growth hormone, not by body size alone. Some cats develop the characteristic facial and skeletal changes without becoming noticeably heavy, and others may be lean despite the hormonal abnormality. The diagnosis rests on biochemical and imaging findings rather than appearance.
"Once a cat's diabetes is diagnosed, any difficulty with insulin means the insulin type or dose is wrong."
Diabetes that remains poorly controlled despite appropriate insulin therapy can signal an underlying condition such as acromegaly, rather than a problem with the insulin itself. Insulin resistance driven by excess growth hormone means the body's response to insulin is blunted, and simply increasing the dose or changing the product may not resolve the issue. Persistently high glucose in the face of escalating insulin doses can be a useful signal that further investigation may clarify the picture.
"Acromegaly is a terminal diagnosis with no options."
While acromegaly is a chronic condition requiring ongoing management, several approaches exist to reduce growth hormone levels, improve glucose control, and monitor for complications. Some cats respond well to treatment and live for years with a reasonable quality of life, while others progress more quickly or experience complications. The trajectory varies widely between individuals, and the picture often becomes clearer with time and repeated assessment.
Related conditions
Diabetes Mellitus in Cats
Acromegaly in cats is often accompanied by diabetes mellitus, because the excess growth hormone interferes with how insulin works, making blood glucose harder to regulate. Many cats with acromegaly present initially with diabetes that responds poorly to insulin treatment.
Hyperthyroidism in Cats
Hyperthyroidism can produce some overlapping signs with acromegaly, including increased appetite, weight changes, and altered behaviour, which may make distinguishing the two conditions more difficult in older cats. Both are endocrine disorders affecting metabolism, though through entirely different mechanisms.
Systemic Hypertension in Cats
Cats with acromegaly may develop systemic hypertension, as the excess growth hormone and associated metabolic changes can affect blood vessel tone and fluid regulation. Hypertension in turn carries implications for the eyes, kidneys, and heart that may complicate the clinical picture.
Hypertrophic Cardiomyopathy in Cats
The chronic hormonal effects of acromegaly can lead to structural changes in the heart muscle, including hypertrophic cardiomyopathy, in which the heart walls thicken and become less efficient at pumping blood. This connection reflects the growth hormone's influence on tissues throughout the body, not only bone and soft tissue.
Chronic Kidney Disease in Cats
Chronic kidney disease may develop or progress in cats with acromegaly, as the metabolic disturbances and hypertension associated with excess growth hormone can place sustained stress on the kidneys over time. Both conditions are often managed concurrently in older cats.
Once acromegaly has been identified, conversations often turn to how diabetes is behaving, whether organ changes such as heart or kidney enlargement are present, and what combination of monitoring and intervention fits the household and the individual cat. The pattern of signs and the response to initial steps tend to clarify over weeks to months, and many owners find it useful to revisit the picture at intervals rather than expecting immediate answers. Understanding how growth hormone affects the body more broadly, and how that intersects with other aspects of metabolic health, can provide context for the choices that unfold.
Last reviewed: 1 July 2026 · Dr Alastair Greenway MRCVS