Tiger, Tiger sitting tight

Tiger is just on his way home after having his blood pressure checked. He sat quietly while we wrapped a cuff around his arm. He thought the cold gel we put on his wrist for the Doppler probe was the worst part.
Because a cat's pulse is so small we have to amplify it with the Doppler. We pump the cuff up until we cannot hear the pulse and then slowly let the air out until we hear the pulse. At this point we read his blood pressure from the dial.
Tiger has a heart murmur and kidney problems. Heart disease often lowers the blood pressure but kidney failure increases it. Fortunately Tiger's blood pressure is normal.

High blood pressure

Hypertension is the medical term for high blood pressure, a silent killer of older cats.

What causes hypertension in cats?

Hypertension is usually secondary to another disease. Kidney disease is the most common cause of hypertension but cats with adrenal gland tumours or treated for hyperthyroidism also develop high blood pressure at times. Sometimes no underlying cause is found.

Most cats with hypertension are older than 9 years of age.

What are the effects of hypertension?

Hypertension damages all body organs but we notice it most in:

• the eyes. The small vessels in the retina break under pressure. The bleeding detaches the retina and the cat becomes blind.
• the brain. Ruptured blood vessels cause ‘strokes’, fits, twitches or unusual behaviour
• the kidneys. Increased blood pressure damages the delicate filtration system of the kidney.
• the heart. The heart has to work harder to push the blood out into the body and the heart muscle thickens and becomes less efficient. Sometimes the heart goes out of rhythm or we hear a murmur with the stethoscope. Affected cats may show signs of heart failure such as breathlessness, lethargy, weakness or fainting.

How do we detect hypertension?

We measure the blood pressure of all cats over 9 years old as part of the regular seniors’ examination. We also check the blood pressure of all cats with kidney disease or hyperthyroidism, or with any signs of eye, brain or heart disease. 

Most cats tolerate the cat sized cuffs we put on their arms. Some don’t like the feel of the gel or the sound of the amplifier we use to hear the pulse. We try to put them at ease so that we get an accurate reading.

How do we treat hypertension?

A daily dose of amlopidine as a fragment of tablet (Norvasc), or as chicken, fish, cheese or beef flavoured drops to put on the food, brings the blood pressure down rapidly.

After a week on amlopidine we recheck the blood pressure to see if it has come down to normal. If all goes well we recheck it every 3 months. 

Sometimes other medications like benazepril (Fortekor or Vetace) are added in, particularly if we detect kidney disease.

Mojo

Mojo is very popular with us all at Hall Vet Surgery, and of course much loved by his family. Two weeks ago he disappeared for a night and when he came home couldn't get interested in his food – very unusual for MoJo and most distressing for all his fans! 

When we saw him we found a few scabs on his head, presumed he’d been in a brawl and sent him home with antibiotics.

Although we noticed a heart murmur we didn’t take much notice of it because many cats have murmurs and never show signs of them.

Next day his owner searched the house for him. She found him hiding in a cupboard and still not the slightest bit interested in breakfast. His breathing seemed a little laboured so we took an X ray of his chest. His heart was hidden by fluid around the lungs.

We drained the fluid and he was much happier. It was clear fluid, possibly as a result of his heart murmur. An ultrasound confirmed that he has hypertrophic cardiomyopathy and that his heart is failing to pump efficiently.

Just as we thought we could let him go home on fluid removal medication he started limping on a front leg.

Cats with heart failure sometimes throw clots into the bloodstream which end up blocking vital arteries. Poor Mojo had a clot in the artery to his front leg. Fortunately it must have been a small one because with heparin therapy it dissolved and Mojo is on aspirin to prevent more clots forming.   

Signs of heart failure are rare in cats even when they have murmurs we can easily hear with a stethoscope. When the blood is so turbulent that it causes clots the outlook can be very poor because clots are so hard to prevent.

Mojo is stable for the moment, enjoying his meals and spending a lot of time on his owner’s lap. Regular checks of his chest and blood pressure should help keep him feeling good and his fans happy for a long while yet.