There is a shape of dog that walks into clinics constantly and gets tested far too late.
Ten years old. Drinking bowls dry and asking for more. A belly that has gone soft and round while the legs have got thinner. Hair thinning on both flanks. Panting in a room that is not hot. Keeps getting skin infections.
That dog is usually described as "old". Often it is hyperadrenocorticism: Cushing's disease.
What it is
The adrenal glands produce too much cortisol, the body's own steroid.
Cortisol in excess does exactly what long-term steroid medication does: it drives thirst and appetite, redistributes fat to the abdomen, wastes muscle, thins skin, suppresses immune function and interferes with hair growth.
Three forms:
- Pituitary-dependent, a small benign pituitary tumour driving the adrenals. The large majority of cases
- Adrenal-dependent, a tumour on an adrenal gland itself
- Iatrogenic, caused by prolonged steroid medication. Clinically identical, entirely different treatment
That last one matters. Steroids are widely and sometimes casually prescribed for itchy dogs in India, and a dog on long-term steroids developing this picture is a different problem requiring a careful taper rather than cortisol-lowering drugs.
The signs
Drinking and urinating a lot. Usually the first thing owners notice, and often dramatic, accidents overnight in a previously clean dog, bowls emptied repeatedly.
Increased appetite. Often ravenous, sometimes scavenging or stealing in a dog that never did.
The pot belly. A sagging, rounded abdomen caused by fat redistribution and weakening abdominal muscle. The classic contrast is a round middle on a dog whose legs are getting thinner.
Skin and coat:
- Symmetrical hair loss over the trunk, with the head and legs typically spared
- Thin skin that bruises or tears easily
- Comedones, blackheads, especially over the belly
- Poor wound healing
- Recurrent skin infections
Panting, often at rest and in comfortable temperatures.
Muscle weakness and lethargy, difficulty with stairs, a hind end that gives way.
Recurrent urinary infections, sometimes without any obvious signs, because cortisol masks the inflammation.
Diagnosis takes more than one blood draw
Worth understanding in advance, because owners are often surprised by the process and the cost.
A resting cortisol cannot diagnose Cushing's. Cortisol fluctuates, and stress alone raises it, a nervous dog at a clinic will have a high reading.
Screening uses a dynamic test, meaning the response to a stimulus is measured rather than a single level:
- ACTH stimulation test, a baseline sample, an injection, then a second sample
- Low-dose dexamethasone suppression test, a baseline, an injection, then samples at four and eight hours
Both mean several hours at the clinic. Then further testing, often including ultrasound, distinguishes pituitary from adrenal disease, because treatment differs.
Expect the workup to take more than one visit. That is normal and not a sign of an indecisive vet.
Treatment
Most dogs are managed medically with a daily oral medication that reduces cortisol production. Many live well for years.
The monitoring is not optional. The risk in treatment is over-suppression, pushing cortisol too low produces an Addisonian crisis, which is an emergency in its own right.
Signs of over-suppression that every owner on this medication must know: vomiting, diarrhoea, marked lethargy, weakness, refusing food, collapse. Stop the medication and contact your vet immediately if these appear.
Adrenal tumours may be surgical candidates, which is a specialist conversation.
Iatrogenic cases are managed by tapering the steroid, carefully, never abruptly, because sudden withdrawal causes its own crisis.
Should an old dog be treated?
An honest question that deserves an honest answer.
Treatment involves ongoing medication cost, regular monitoring blood tests, and some risk.
Reasonable to treat: a dog drinking litres and unable to hold urine overnight, losing muscle, getting repeated infections, with skin breaking down. There is real quality of life to recover.
Reasonable to monitor instead: a mildly affected elderly dog with other serious conditions, where the disease is not the thing limiting its life.
This is a conversation to have properly with your vet rather than an automatic yes. Cushing's is one of the conditions where "we found it" and "we should treat it" are genuinely separable.
The bottom line
An older dog that is drinking constantly, has developed a pot belly while its legs thin, is losing hair symmetrically on both flanks, has skin that bruises easily, and pants in a cool room. That dog should be tested, not written off as old.
Understand that diagnosis takes a dynamic test and several hours, not one blood draw.
And if your dog has been on steroids long term and looks like this, say so early. That is a different diagnosis with a different fix.
Increased drinking is shared with kidney disease and diabetes. The pot belly, thin skin and symmetrical hair loss are what point here specifically.