Cat Suddenly Crying Out With Hind Leg Paralysis: A Clot Emergency

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Cat Suddenly Crying Out With Hind Leg Paralysis: A Clot Emergency

Cats do not bark. When a cat makes a sudden, loud, unmistakable noise it has never made before, it is not raising an alarm the way a dog does. It is usually in severe pain, and the most serious cause is a blood clot lodged where the main artery divides toward the back legs.

The picture is distinctive. A cat cries out or screams, then cannot use one or both hind legs, drags itself, and the affected legs are cold, the pads and nail beds are pale or bluish, and the thigh muscles feel hard. This is aortic thromboembolism, sometimes called a saddle thrombus, and it is one of the most painful conditions in feline medicine.

• Sudden crying out plus hind leg weakness is an emergency in minutes, not hours.
• Feel the paws. Cold back paws with pale or grey pads is the single most useful home finding.
• Never give aspirin, ibuprofen, paracetamol, or any human painkiller to a cat. Several are lethal.
• The clot almost always comes from underlying heart disease that had never been diagnosed.
• Most affected cats had no symptoms at all the day before.

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Never give a cat any human medication, and especially not aspirin.

Owners who read that a clot is involved reach for aspirin. Aspirin is dosed for cats in a completely different way from people and giving it at home can cause fatal bleeding. Paracetamol, known as acetaminophen, destroys a cat's red blood cells and kills at doses smaller than a single human tablet. Ibuprofen causes kidney failure and stomach ulceration. A cat in this much pain needs veterinary pain relief within minutes, and nothing in a household medicine cabinet is safe to bridge the gap.
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Decide in 60 seconds

Why a clot does this

Most cases begin in the heart. Hypertrophic cardiomyopathy thickens the heart muscle, the upper chamber on the left stretches, and blood swirls instead of flowing cleanly through it. Blood that moves slowly and turbulently clots.

The clot then leaves the heart and travels down the aorta until the vessel narrows. That happens where the aorta divides to supply the two hind legs, which is why the clot sits astride the split and gets the name saddle thrombus.

Below that point, blood stops arriving. Muscle and nerve deprived of blood supply lose function within minutes, which is why the paralysis is immediate and complete rather than gradual.

The pain is extreme and it comes from the tissue itself being starved, not from an injury. The clot also releases substances that constrict the surrounding smaller vessels, which is part of why restoring flow is difficult even after the main obstruction is dealt with.

Two things make this an emergency rather than an urgent problem. Time without blood supply determines how much muscle and nerve survives, and the heart disease behind it is often producing fluid in the lungs at the same time.

The cruel part is that cats conceal heart disease unusually well. Many affected cats have never had a murmur detected, have never coughed, and were behaving completely normally that morning.

The signs, in the order you notice them

The noise.

A sudden, loud, drawn-out cry, howl, or scream. Owners describe it as a sound they had never heard the cat make. It often happens as the cat jumps down or moves.

Loss of the back legs.

The cat cannot stand on them, drags itself forward on the front legs, or falls over trying. It may keep trying to get up and cry each time.

Cold limbs.

Compare a back paw with a front paw. The affected leg feels noticeably colder because no warm blood is reaching it.

Pale pads and nail beds.

The pads and the quick of the claws look white, grey, or bluish rather than pink.

Hard, tense thigh muscles.

The muscles at the back of the affected leg feel firm and board-like and touching them hurts.

No pulse in the leg.

A vet checks the femoral pulse in the groin and finds it absent. This is not something to attempt at home on a screaming cat.

Breathing changes.

Fast breathing, effort, or open-mouth breathing. Cats do not pant like dogs, so an open mouth in a cat that has not just been running is always significant.

Hiding and stillness.

Some cats do the opposite of crying and simply go silent and hide. Pain in cats is as often withdrawal as it is noise.

Clinicians use a shorthand of five signs for this: pain, pallor, pulselessness, paralysis, and coldness. If you have three of them, you do not need the other two before you leave for the clinic.

What to do in the first five minutes

Phone the nearest clinic that is open, on speaker, and say the cat has suddenly lost the use of its back legs and is crying. Those words move a cat to the front of a queue.

Handle as little as possible. Slide a towel or a flat piece of card under the cat and lift the whole cat as a unit rather than picking it up around the middle, which drags the painful limbs.

Put the cat in a carrier lined with a soft towel, with the top removed if the carrier opens from above, so it can be lifted straight out at the clinic without another painful handling.

Keep the room quiet and the journey quiet. A cat that also has fluid on its lungs can be tipped into respiratory crisis by stress, so no loud radio, no other pets in the car, and no repeatedly opening the carrier.

Keep the cat generally warm with a towel over the carrier, but never apply a hot water bottle, heat pad, or hair dryer to the affected legs. The limbs have no sensation and no blood flow to carry heat away, and owners have caused serious burns doing this with good intentions.

Do not massage or rub the legs. It hurts and it does not help.

Do not offer food or water and do not give any medication.

Go. Do not wait to see whether it settles, and do not wait until the morning. Every minute without blood supply costs tissue.

What else makes a cat cry out

The template this article replaced treated cat noise as a behaviour threshold to manage. It is more useful as a diagnostic list, because a cat that starts vocalising in a new way is nearly always reporting something.

Straining and crying in the litter tray.

In a male cat this is a urinary blockage until proven otherwise, and it is an emergency on the same timescale as a clot.

Loud night yowling in an older cat.

Overactive thyroid, high blood pressure, failing vision or hearing, and cognitive decline all produce it. These are all diagnosable and most are treatable.

Yowling in an unspayed female.

Oestrus. Loud, repetitive, and accompanied by rolling and treading. Normal, and a reason to discuss neutering.

Crying when touched, picked up, or jumping.

Localised pain. Arthritis in older cats is far more common than owners think and cats rarely limp with it.

Growling and hissing at people the cat likes.

Pain or fear rather than temperament. A sudden change in a friendly cat deserves an examination.

Crying at doors and windows.

Usually behavioural, and worth ruling out the medical list first if it started abruptly.

Because cats have no bark, there is no equivalent of nuisance barking to threshold or train out. A cat making a new loud noise is a cat with a new reason.

Reducing the risk before it happens

You cannot prevent a clot directly at home, but you can find the heart disease behind it, and that is where the leverage is.

Count sleeping breaths.

The single most useful home measurement for feline heart disease. Watch the chest while the cat is genuinely asleep and count breaths for a full minute. A rate under about thirty is the usual reference point, and a rate consistently above it, or a rising trend, is a reason to call the vet even in a cat that seems well. Ask your vet what number they want you to act on for your cat.

Have the heart listened to at every visit.

A murmur or a gallop rhythm is a reason to image the heart. The absence of a murmur does not rule heart disease out, which is why the breathing count matters too.

Screen the at-risk breeds.

Maine coons, ragdolls, British shorthairs, sphynx, Persians and several others have a recognised predisposition. Ask about screening rather than waiting for signs.

Take an abrupt change in activity seriously.

A cat that stops jumping to its usual places, sleeps in a new low spot, or breathes faster after mild activity is worth checking.

What never to do

Do not give aspirin, ibuprofen, paracetamol, naproxen, or any human painkiller. Several are fatal to cats at very small doses.

Do not give medication prescribed for another pet, or a leftover course from a previous illness.

Do not apply direct heat to the affected legs.

Do not massage, stretch, or manipulate the limbs.

Do not carry the cat by lifting it under the abdomen. Support the whole body on a flat surface.

Do not delay to film the episode. The clinic needs the cat, not the footage, and this is one of the few situations where documentation costs more than it gives.

Do not conclude that a cat which has gone quiet has improved.

Do not let a cat with breathing difficulty be chased or cornered to be caught. Stress alone can be fatal in a cat in heart failure. Close doors, reduce the space calmly, and use a towel.

When to get help

Go immediately, at any hour, for a cat that cries out and then cannot use its back legs, for cold or pale paws, for open-mouth breathing or panting, for a male cat straining in the litter tray, or for sudden collapse.

Go the same day for crying when handled, a friendly cat that has started growling or hiding, a new limp, or a cat that has stopped jumping to places it always used.

Book this week for night yowling in an older cat, gradual hind leg weakness with no pain, or any change in voice that has lasted more than a few days.

Bring the carrier without transferring the cat again, the age and breed, the sleeping breath counts if you have them, any known heart murmur, the exact time the noise happened, which legs are affected, and a list of anything the cat may have been given. Say on the phone that the cat has lost the use of its back legs, because that description alone tells a clinic to prepare for pain relief and oxygen before you arrive.