Secondary hypertension is the most common form, but “almost always” is too strong: investigations find no underlying disease in some cats. This is called idiopathic hypertension. A cause may also become apparent during later monitoring, so normal initial blood and urine results do not make persistently high pressure harmless.
When to see a vet urgently
Seek urgent assessment if your cat develops any of these changes:
- sudden loss of vision, bumping into familiar objects or difficulty finding the food bowl;
- visible bleeding in an eye or suddenly changed pupils;
- seizures, marked confusion or a severe balance problem.
Do not wait for the next planned blood pressure check: find a vet near you.
Overview
A cat's blood pressure reflects cardiovascular function and blood vessel condition. When pressure rises above normal, vessel walls are subjected to ongoing strain and gradually become damaged. This affects the target organs: the eyes, with retinal vessel rupture and blindness; kidneys, with reduced filtration; heart, with muscle thickening; and brain, with neurological problems.
Systolic pressure is the pressure in arteries when the heart contracts. This is usually the main value assessed in cats. Listening to a fast heartbeat or observing restlessness cannot show how high blood pressure is. Measurement is also needed because significant target-organ damage can develop before an obvious behavioural change.
Causes
The most common underlying conditions causing hypertension in cats include:
- chronic kidney disease, or CKD,
- hyperthyroidism, with excess thyroid hormone increasing the heart's workload,
- diabetes mellitus,
- excess weight,
- adrenal tumours, such as phaeochromocytoma,
- stress, which may cause temporary rises.
A rise during measurement caused by stress is distinguished from persistent hypertension. It does not alone establish ongoing disease. Links between diabetes, excess weight and blood pressure are also less certain in cats than people; they should not be considered as well-established causes as chronic kidney disease. Investigation considers the overall picture and, where needed, rarer hormonal causes too.
Risk factors
- older age, over 7–8 years,
- chronic kidney, liver or thyroid disease,
- excess weight and inactivity,
- inherited predisposition.
Research on risk factors in cats is partly limited. Inheritance, liver disease and inactivity in particular cannot be considered definite independent causes on the basis of this list. Older age and certain concurrent conditions help target monitoring, but hypertension is neither confirmed nor ruled out by breed or weight.
Symptoms
Hypertension may develop slowly, and early signs often go unnoticed. Persistently high pressure may cause:
- sudden loss of vision or blindness from retinal tears,
- enlarged pupils responding poorly to light,
- bleeding into the eyes,
- disorientation, an unsteady gait and seizures,
- a pounding heartbeat and breathlessness,
- tiredness and loss of appetite.
Retinal problems may involve bleeding, swelling and detachment rather than necessarily tearing. Vision loss can seem sudden even when a cat has adapted to gradually worsening sight and the change is noticed late. Reduced jumping or caution in familiar surroundings, for example, may only come to mind after the cat starts bumping into things.
Not every eye or neurological symptom is caused by blood pressure. Investigation is nevertheless urgent because prompt treatment may reduce permanent damage. Hypertension is not assessed solely by whether the eye looks abnormal externally: changes at the back of the eye may require veterinary examination.
Possible complications
Untreated hypertension can cause:
- blindness from retinal detachment,
- progression of chronic kidney disease,
- heart failure,
- strokes and neurological problems,
- reduced quality and length of life.
Heart muscle thickening may develop as the heart pumps against greater resistance. However, true heart failure is a much rarer consequence of feline hypertension than the list might suggest. Heart ultrasound can be used where needed to investigate a murmur or structural change.
The kidneys can both cause hypertension and be a target organ damaged by it. High pressure can increase protein loss in urine. Kidney values, urine testing and blood pressure monitoring therefore complement each other. Lowering pressure alone does not replace investigation of concurrent kidney disease or nutritional assessment.
Diagnosis at the vet
Blood pressure is measured with a specialised device using a cuff on the tail or a limb. Additional tests may include:
- an eye examination to detect retinal damage,
- blood and urine tests to assess kidney and thyroid function,
- ultrasound of the heart and internal organs.
The appointment also reviews medicines and previous results. Examination of the back of the eye may reveal pressure-related damage even before the cat bumps into things. A urine protein-to-creatinine ratio may assess the amount of protein loss. If an adrenal hormonal disorder is suspected, tests target that suspicion rather than automatically giving every cat the same extensive test package.
Several measurements in calm surroundings are important to minimise stress effects.
Without signs of target-organ damage, an unexpectedly high reading may require another measurement visit. By contrast, sudden blindness or serious neurological signs consistent with hypertension may require urgent treatment. Repeat measurements aim to distinguish a temporary rise from ongoing disease reliably, rather than delay help for a symptomatic cat.
How blood pressure is measured
ISFM's 2017 guidelines advise several consecutive measurements in calm surroundings after the cat has become accustomed to the room. Hypertension is described when systolic pressure is repeatedly above 160 mmHg. Cats over 7 years old should have blood pressure measured at least annually; those over 10, or with chronic kidney disease or hyperthyroidism, need more frequent checks. One under-recognised cause of high blood pressure and low potassium is primary hyperaldosteronism, or Conn's syndrome: excess aldosterone production caused by an adrenal tumour or hyperplasia.
Measurement works best before blood sampling and other stressful procedures. The cat can remain in a comfortable position, and staying in the carrier base or using a familiar blanket sometimes helps it settle. Your presence may also help. Strong restraint and constant movement can distort the result.
Cuff size, location and measurement method affect the reading. These are recorded so later visits are as comparable as possible. Consistent results within the series are assessed; the highest number displayed once does not describe the entire situation.
The 160 mmHg threshold above is part of assessing target-organ damage risk. Interpretation also includes persistence, measurement conditions, underlying disease and existing organ damage. Treatment need is not decided at home by comparing one number with a threshold. New eye or neurological symptoms particularly require prompt overall assessment.
Treatment and follow-up
Treatment aims to reduce damage to the eyes, brain, kidneys and heart. A common medicine is amlodipine, a calcium-channel blocker that widens blood vessels. Some cats receive another medicine or combination, particularly according to concurrent kidney disease and proteinuria. This choice is made by the vet; do not give a cat a person's prescribed blood pressure medicine yourself.
Treating the underlying disease is part of the plan, but treating hyperthyroidism, for example, does not automatically remove the need for separate blood pressure medication. Medication and its effectiveness are assessed by measurement even if the cat starts looking normal again. Treatment often continues long term, and needs may change as disease progresses.
A check-up is needed at the time specified by the vet after starting or changing medication. It assesses general health as well as pressure and, where needed, kidney values, hydration and potassium. Pressure that falls too low can also cause problems. If your cat becomes clearly weak or loses its appetite, contact the treating vet before the next routine visit.
Mention missed medication or difficulty giving it. This helps distinguish treatment not actually received from inadequate drug effect. Do not stop medication simply because vision or behaviour improves. Vision may partly return after prompt treatment, but established damage may also be permanent.
Prevention
- regular veterinary checks, particularly for cats over 7 years old,
- monitoring and treatment of chronic disease,
- maintaining a healthy weight and complete, balanced nutrition,
- reducing stress in the cat's life,
- maintaining exercise and activity.
General wellbeing measures do not replace medication for diagnosed hypertension. Salt reduction alone has not been shown to lower feline blood pressure reliably. Diet is chosen according to factors such as kidney disease and nutritional status; do not replace complete food with unsalted homemade food yourself. Measurements must continue even when your cat seems healthy.
This text provides general information and does not replace veterinary care. If your cat develops symptoms, contact a vet.
Frequently asked questions
Can stress explain high blood pressure?
It can explain a temporary rise, which is why measurements are taken calmly and repeated where needed. Nevertheless, symptoms consistent with target-organ damage should not be dismissed as stress. These require urgent assessment and possible treatment.
Can hypertension be noticed at home before blindness occurs?
Not always, because disease may cause few symptoms for a long time. Blood pressure measurement is therefore part of monitoring at-risk cats. Changed pupils, cautious movement or altered behaviour are reasons to contact a vet, but home observations do not replace measurement.
Can vision lost through hypertension return?
It may partly return if treatment starts quickly and retinal function recovers. Return cannot be promised, and some damage is permanent. Sudden vision changes therefore need investigation without delay.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- ISFM Consensus Guidelines on the Diagnosis and Management of Hypertension in Cats, ISFM / Journal of Feline Medicine and Surgery, accessed 2026-11-03.
- ACVIM Consensus Statement: Guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats, ACVIM / Journal of Veterinary Internal Medicine, accessed 2026-11-03.
- Hypertension, Cornell Feline Health Centre, accessed 2026-11-03.
- Hypertension Toolkit: Measuring Blood Pressure, Feline Veterinary Medical Association, accessed 2026-11-03.
- Hypertension Toolkit: Treatment, Feline Veterinary Medical Association, accessed 2026-11-03.
- Treatment Recommendations for CKD in Cats (2026), International Renal Interest Society, accessed 2026-11-03.
- 2026 iCatCare Consensus Guidelines on the Diagnosis and Management of Chronic Kidney Disease in Cats, iCatCare / Journal of Feline Medicine and Surgery, accessed 2026-11-03.
- Sudden Blindness, Cornell Feline Health Centre, accessed 2026-11-03.
