Blood pressure is one of the measurements we are used to having taken at our own doctor’s visits, but have you ever wondered how cats have their blood pressure taken? Consider how difficult it can be to get a cat to do anything she doesn’t want to do, let alone lay still for 60 seconds while a cuff squeezes her leg.
Let’s discuss what a normal cat blood pressure should be (hint: it’s the same for humans) and what it means if a cat’s blood pressure is high or low.
What’s a Normal Cat Blood Pressure?
Blood pressure is the force that propels blood through the vascular system to deliver oxygen and nutrients to every cell of the body. It’s a measurement that can tell us a lot about a pet’s overall health. When blood pressure becomes high or low it is very dangerous and can mean there is a serious health problem that needs to be addressed.
There are two components to blood pressure: systolic and diastolic. Systolic blood pressure is the maximum pressure during a heartbeat. Diastolic blood pressure is the minimum pressure and occurs between heart beats.
A normal blood pressure reading in cats is 120 mmHg systolic over 80 mmHg diastolic – often represented as 120/80. Kittens have lower normal blood pressure. Veterinarians generally diagnose high or low blood pressure based on a cat’s systolic readings.
A systolic blood pressure above 180 mmHg is considered high (hypertension) while a systolic pressure below 90 is low (hypotension).
Because blood pressure is measured at the vet clinic and many cats are stressed or excited there, your veterinarian will not diagnose your cat with high blood pressure until the systolic reading is greater than 180.
Causes of High Blood Pressure in Cats
High blood pressure in cats can be caused by many different factors but is always due to an underlying disease. These include:
Up to 65 percent of cats with high blood pressure have kidney disease . The relationship is through a complex set of hormone systems and is the reason many cats with kidney disease take blood pressure medication.
The body may constrict blood vessels to compensate for a heart that is unable to adequately pump blood. Unfortunately this worsens heart disease in a vicious cycle.
An overactive thyroid can lead to high blood pressure, high heart rate, and many other dangerous changes in body function. Hyperthyroid disease is common in middle aged to older cats.
Tumors or Cancer
Some types of cancers or non-cancerous tumors can secrete hormones that lead to hypertension while others create hypertension due to their size or location.
Severe pain or an injury – such as a broken leg – can cause temporary hypertension. Adequate pain control quickly settles blood pressure to the normal range.
Trauma can alter the normal mechanisms that control blood pressure, causing hypertension.
Symptoms of High Blood Pressure in Cats
Symptoms of high systemic blood pressure in cats are typically seen in association with symptoms of their primary disease. The most common sign of high blood pressure in cats is blindness.
Other signs may include:
- Decreased energy
- Exercise intolerance
- Behavior changes
- Vision problems or blindness
- Seizure or collapse
Other symptoms of feline high blood pressure are evident to your veterinarian upon physical exam including a new or worsening heart murmur and changes to the eye including detachment of the retina.
Consequences of Hypertension in Cats
Untreated hypertension can cause severe illness including blindness, brain damage, seizures, kidney disease, heart disease, and stroke.
Treatment for Cat Hypertension
Treatment for hypertension in cats is two-fold. When possible, treatment plans are focused on addressing or managing the underlying cause of hypertension such as kidney disease, heart disease, or thyroid disease.
Oral medications can reduce blood pressure and are very useful as part of a comprehensive treatment plan. Treatment plans may also include diet changes such as low sodium or prescription diets for management of the primary disease.
What Causes Low Blood Pressure in Cats?
Low blood pressure in cats, also known as hypotension, is caused by severe illness, injury, or trauma. It is very abnormal and always an emergency.
Cats only become hypotensive when their body cannot adequately respond. It can be caused by blood loss, low protein, or infection of the blood as well as any other causes of severe illness such as heart failure or neurologic dysfunction.
Heart failure leads to hypotension when the heart can no longer contract well enough to generate adequate pressure to send the blood through all the vessels of the major organs. Neurologic dysfunction leads to hypotension when the brain cannot send appropriate regulatory signs to the cardiovascular system.
Symptoms of Low Blood Pressure in Cats
Symptoms of hypotension in cats include:
- Very low body temperature
- Sudden death
Treatment for Cat Hypotension
Treatment for hypotension is always an emergency. Cats diagnosed with low blood pressure require immediate in-hospital treatments such as IV fluid therapy, blood transfusions, and fast-acting injectable medications. Only once the cat is stabilized can the primary disease or injury be addressed.
How to Take a Cat’s Blood Pressure
There are two common methods for measuring a cat’s blood pressure in a veterinary clinic – Doppler and Oscillometric.
Doppler is equivalent to a healthcare provider manually taking a person’s blood pressure with a cuff and stethoscope. It is more accurate than the oscillometric method and is generally preferred by veterinarians.
The cat is laid on his side and a cuff is placed around the upper arm or leg. A Doppler crystal is placed on an area of shaved skin usually on the underside of the foot just above the paw pad. The Doppler crystal allows the veterinarian to listen to the pulse of the artery. The cuff is pressurized until the pulse is no longer audible and then relaxed until the sound returns. The pressure at which the pulse sound returns is the systolic blood pressure.
This process is repeated 3-5 times and the results are averaged to determine a cat’s systolic blood pressure. The Doppler crystal is very sensitive to movement making this method difficult in awake, healthy cats.
The other method is Oscillometric. This method involves a machine with internal algorithms that translate changes in volume into pressure. A cuff attached to the machine is placed on the cat’s upper arm or leg. The cuff is pressurized and the machine determines the volume of the body part in the cuff at both its peak (systole) and valley (diastole).
The machine takes at least 5 readings and averages the middle three before performing calculations to translate the volume into blood pressure. This method is less prone to user error but is more likely to be inaccurate.
Can You Take a Cat’s Blood Pressure at Home?
While blood pressure is a useful measurement in assessing your cat’s overall health, it is not generally recommended that you try to take it at home. It is far more useful to monitor your cat for more easily recognized symptoms such as lethargy, vision loss, and changes in behavior.
If your veterinarian is concerned about your cat’s blood pressure she will likely ask you to have it rechecked in the clinic as needed. This allows for consistency in the procedure as well as less stress for you over inaccurate high and low readings. If your cat is behaving normally and not exhibiting any signs of illness then his blood pressure is likely to be within the normal range.
If your cat has been diagnosed with high blood pressure the best thing you can do at home is administer her prescribed medications on schedule. If giving your cat a pill is difficult ask your veterinarian about different formulations such as liquids or chewable tablets. Report changes in behavior to your veterinarian who will make recommendations for assessment.
How to Support Healthy Cat Blood Pressure
The best things you can do for your pet’s overall health will also support healthy blood pressure. These include maintaining a healthy weight, getting regular exercise, eating a nutritious commercially formulated cat food, and developing a relationship with your veterinarian through routine healthy visits.
- Lawson JS, Jepson RE. Feline comorbidities: The intermingled relationship between chronic kidney disease and hypertension. J Feline Med Surg. 2021 Sep;23(9):812-822.