Hyperaldosteronism in Cats: Low Potassium and Weakness

A cat who suddenly struggles to jump onto the couch, walks with a stiff or wobbly gait, or holds the head low with the chin tucked toward the chest is telling you something important. One condition that can cause this combination of signs is hyperaldosteronism, also called Conn's syndrome. It happens when the adrenal glands make too much of a hormone called aldosterone, which pulls potassium out of the body and can push blood pressure up. Hyperaldosteronism was once considered rare in cats, but veterinarians now recognize it more often, especially in middle-aged and older cats. This guide explains what the condition is, why it causes weakness and high blood pressure, how it is diagnosed and managed, and which signs need prompt care.

Important: This article shares general educational information for pet owners and is not a substitute for an in-person veterinary examination, diagnosis, or treatment. For any medical concern or emergency, contact your veterinarian promptly.

What Is Hyperaldosteronism?

Cats have two small adrenal glands, one near each kidney. These glands produce several hormones, including cortisol, adrenaline, and aldosterone. Aldosterone belongs to a group called mineralocorticoids, and its main job is to help the body balance sodium, potassium, and water.

In a healthy cat, aldosterone acts on the kidneys. It signals them to hold on to sodium and water while letting potassium go into the urine. Normally, production rises and falls with the body's needs.

In hyperaldosteronism, the adrenal glands keep producing aldosterone even when the body does not need it. When the problem starts in the adrenal gland itself, it is called primary hyperaldosteronism, or Conn's syndrome. This is the form most often discussed in cats.

Why too much aldosterone matters

Excess aldosterone has two big effects. First, the kidneys lose too much potassium, so blood potassium drops, a state called hypokalemia. Second, the body holds on to extra sodium and water, which can raise blood pressure.

What Causes It in Cats

Primary hyperaldosteronism in cats generally has one of two causes, and which one is present shapes the plan.

Adrenal tumor

In many cats, the condition comes from a tumor in one adrenal gland that produces aldosterone on its own. These tumors can be benign growths called adenomas or malignant growths called carcinomas.

Adrenal hyperplasia

In other cats, both adrenal glands are enlarged in a diffuse way rather than having a single tumor. This is called bilateral adrenal hyperplasia. The exact trigger is not fully understood. Signs may be more gradual.

Who is at risk

The condition is seen most often in middle-aged and older cats. It is not caused by anything an owner did. Because the signs can look like normal aging, kidney disease, or other hormone problems, it may be overlooked unless potassium and blood pressure are checked.

Signs That Warrant a Veterinary Exam

Signs can appear suddenly or develop slowly. Some cats show mostly muscle signs, some mostly signs of high blood pressure, and some both. Each of these warrants an exam, and sudden blindness, blood in the eye, or severe weakness need care right away:

None of these signs is unique to hyperaldosteronism. Low potassium and high blood pressure can also occur with kidney disease, an overactive thyroid, and other conditions. That is why testing matters so much.

Neck Ventroflexion and Muscle Weakness Explained

Potassium is essential for normal muscle and nerve function. When blood potassium falls too low, muscles become weak and may even break down, a problem veterinarians call hypokalemic polymyopathy.

What ventroflexion looks like

The neck muscles that hold a cat's head up are among the first to show weakness. Unlike dogs, cats lack a strong ligament that helps support the head, so they depend heavily on muscle strength. When those muscles weaken, the head droops forward and down, with the chin pointing toward the chest. This posture is called cervical ventroflexion.

Other muscle signs

Weakness often affects the legs as well. A cat may walk with a crouched, stiff, or shuffling gait, or stand with the legs spread wide. In severe cases, weakness can involve the muscles used for breathing, which is an emergency.

Weakness from low potassium can come and go at first, so a cat that seems normal one day and weak the next still warrants an exam.

High Blood Pressure and the Eyes

Because aldosterone causes the body to retain sodium and water, many cats with hyperaldosteronism develop high blood pressure, also called systemic hypertension. Our guide to high blood pressure in cats explains this condition in more depth.

High blood pressure often causes no obvious signs until it damages delicate tissues. The eyes are especially vulnerable. Pressure can cause bleeding inside the eye, swelling of the retina, or retinal detachment, which can lead to sudden blindness. Owners may first notice dilated pupils, redness inside the eye, or a cat bumping into things.

High blood pressure can also strain the heart and kidneys and sometimes cause disorientation or seizures. Sudden vision loss or neurologic signs are emergencies; contact your veterinarian or an emergency clinic right away.

How Veterinarians Diagnose It

No single quick test confirms hyperaldosteronism, so your veterinarian combines several findings.

1. History and physical exam: questions about when signs started and whether they come and go, plus a check of muscle strength, posture, and heart.
2. Blood pressure measurement: a cuff on a leg or the tail, often repeated to account for clinic stress.
3. Eye exam: the back of the eye can show damage from high pressure.
4. Bloodwork and urinalysis: potassium, sodium, and kidney values, plus a muscle enzyme called creatine kinase.
5. Hormone testing: aldosterone is measured, sometimes alongside a related hormone called renin.
6. Imaging: ultrasound or CT scans examine both adrenal glands and nearby blood vessels.

Your veterinarian may also test thyroid levels, because an overactive thyroid is a common cause of high blood pressure in older cats. Our guide to understanding your pet's blood work can help you make sense of the results.

Management Options Your Veterinarian May Discuss

The plan depends on the cause, your cat's overall health, and any other conditions such as kidney disease.

Stabilizing first

Cats with very low potassium or severe weakness often need hospital care first. Your veterinarian may give potassium through an intravenous line and monitor blood levels closely until the cat is stronger.

Surgery for a single adrenal tumor

When one adrenal gland has a tumor and the other gland looks normal, surgical removal of the affected gland, called adrenalectomy, may be recommended. This major operation carries real risks, but for suitable candidates it may resolve the hormone excess.

Long-term medical management

When surgery is not possible or not chosen, or when both glands are affected, cats are often managed with medication. This may include oral potassium supplementation, a type of drug called an aldosterone antagonist, and blood pressure medication such as a calcium channel blocker, all as prescribed by your veterinarian. Medical management addresses the effects of excess aldosterone rather than removing its source, so ongoing monitoring is important.

Never give your cat potassium products or any other medication without veterinary guidance. Too much potassium can be just as dangerous as too little.

Living With a Cat Who Has Hyperaldosteronism

Many cats live comfortably once the condition is identified and managed. Home care focuses on medication, monitoring, and easing daily life.

• Give medications as directed: follow instructions exactly and ask for tips if your cat resists pills.
• Keep recheck appointments: repeat potassium, blood pressure, and kidney checks guide adjustments.
• Make resting spots easy to reach: add steps or ramps to favorite high resting spots, and keep food, water, and the litter box on one floor.
• Choose a low-sided litter box: a weak cat may find it hard to step over tall sides.
• Keep a simple log: note appetite, thirst, energy, head posture, and any changes in vision.

Kidney disease is common in older cats and may occur alongside hyperaldosteronism. Our guide to chronic kidney disease in cats covers daily care in more detail.

When to Call Your Veterinarian

Schedule a prompt veterinary visit if your cat shows any of the following:

• A drooping head or difficulty holding the head up
• New reluctance to jump, a stiff walk, or weakness that comes and goes
• Increased thirst or urination, weight loss, or a reduced appetite
• A gradual change in the appearance of the eyes
• A previous diagnosis with new or worsening signs

Contact your veterinarian or an emergency clinic right away if

• Your cat cannot stand or walk, or collapses
• Breathing is labored, rapid, or open-mouthed
• Vision seems to disappear suddenly, the pupils stay wide open in normal light, or you see blood inside the eye
• Your cat has a seizure, seems confused, or tilts the head and circles
• Your cat refuses all food or water, or vomits repeatedly

These signs can reflect dangerously low potassium or very high blood pressure, and they need veterinary care right away.

Common Mistakes and Myths

Myth: Weakness and a lowered head are just old age.

Fact: a drooping head, new trouble jumping, or a wobbly walk are not normal aging.

Mistake: Giving potassium at home without testing.

Too much potassium can affect the heart, so supplementation should only happen as prescribed by your veterinarian.

Myth: If my cat seems normal again, the problem is gone.

Fact: weakness from low potassium can fluctuate. A cat who improves still needs a workup and follow-up testing.

Mistake: Skipping blood pressure checks.

High blood pressure often has no visible signs until eye or organ damage occurs. Regular measurements are an important part of monitoring.

Frequently Asked Questions

Is hyperaldosteronism the same as Cushing's disease?

No. Both involve the adrenal glands, but Cushing's disease involves excess cortisol, while hyperaldosteronism involves excess aldosterone.

Can hyperaldosteronism be confused with hyperthyroidism?

Yes, because both can cause weight loss and high blood pressure in older cats, and both can occur together. Your veterinarian may test thyroid levels as part of the workup. Our guide to hyperthyroidism in cats explains that condition.

Is the condition painful?

Muscle weakness from low potassium can be uncomfortable, and some cats seem sore when handled.

Will my cat need lifelong medication?

Cats managed medically usually stay on medication long term. If a single tumor is removed surgically, some cats may no longer need it. Your veterinarian will guide you based on your cat's situation.

Can lost vision return?

Sometimes, if high blood pressure is brought under control quickly and the retina reattaches. Outcomes vary, which is why sudden vision changes need veterinary care right away.

Key Takeaways

Hyperaldosteronism, or Conn's syndrome, occurs when the adrenal glands make too much aldosterone, usually from an adrenal tumor or enlargement of both glands. The resulting potassium loss causes muscle weakness and the drooping head called neck ventroflexion, and raised blood pressure can damage the eyes and organs. Diagnosis combines an exam, blood pressure and eye checks, bloodwork, hormone testing, and imaging. Management may involve surgery for a single tumor or long-term medication, as prescribed by your veterinarian, along with regular monitoring. Seek emergency care right away for collapse, labored breathing, sudden blindness, or seizures, and schedule an exam for any new weakness, head drooping, or change in thirst.