What is a dog blood clot in a leg?

A dog blood clot in a leg is a medical emergency. A dog with a blood clot in a leg may experience intense pain, swelling, and difficulty walking. If the blood clot is large, it may block the flow of blood to the leg, causing gangrene. If the blood clot is small, it may simply cause pain and swelling. If the blood clot is not treated, it may cause the leg to die.

That's a question I recently had to answer for the worried parents of a middle-aged Labrador Retriever.

Murphy is a typical, eager 6-year-old Lab, a happy soul whose tail is constantly wagging.However, this energetic ball-chasing dog had awoken unable to walk that morning.

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Back legs of a dog suddenly stop working

Murphy's worried humans called in, saying he was limping and they didn't know which leg he was limping on.

Murphy was unable to stand after thirty minutes in the waiting room and had to be carried into the exam room.

A history is always important.

Murphy's story was remarkable for its simplicity:

• He had been fine the day before but awoke the next morning with a weak back end.
• He kept collapsing as he bravely attempted to stand, despite the fact that his tail was still wagging.

Murphy didn't appear to be in pain, but his back legs couldn't support his weight, so I examined him while his person supported him in a standing position.

Murphy’s Physical Exam

Broken bones seemed unlikely in Murphy's case, given his lack of a history of trauma.

Even so, it's critical to look for fractures and dislocations, which Murphy did not have, nor did he have painful joints.

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A simple test of flipping Murphy's back paw upside down revealed that it remained that way; this is known as the "placing reflex," and it tests the nerves that run from his paw up into his spinal cord and brain stem.When the dog is unaware that his paw is turned upside down, the vet concludes:

• The dog is unaware that the paw is turned upside down (the placement nerves are not functioning); OR
• He is aware that it is upside down, but the leg does not receive the nerve message to flip it over (the do-something-about-it nerves are not functioning); OR
• His muscles are too weak to react to nerve signals.

Murphy's problems appeared to be neurological, given his good muscle tone.

The next step was to test more nerve reflexes to confirm this was a neurological problem and pinpoint the location. To do so, I had Murphy lie on his side and tested one back leg at a time as follows:

• Toe pinch: This may seem unfair, but it's an important test of "deep pain sensation." If the dog is unaware that the skin between his toes is being pinched, it's a sign of severe nerve damage. Fortunately, Murphy pulled back and had sensation on both hind legs (also a good sign for muscle tone).
• Patellar reflex: You've probably had this done to you, where the doctor taps the ligament just below the kneecap.In Murphy's case, his lower leg continued to vibrate for much longer than it should have, indicating that the brain isn't receiving a message to dampen the reflex, which usually indicates a spinal lesion.
• Skin sensation: A hypodermic needle is used to touch the skin in various locations, and when full sensation is present, the skin should ripple.Murphy had hit-or-miss sensation along his lower back, thighs, and the tops of his paws, but he had sensation on part of his lower back legs.

That brings us back to the main point: why were his back legs so weak?

Why have my dog's back legs stopped working?

When confronted with a problem, the vet creates a mental list of possible solutions (in vet speak, this is referred to as a "differential diagnosis" list). For Murphy, mine went something like this:

Disc Disease

Disc disease is a common cause of a dog's back legs suddenly not working, but Murphy didn't appear to be in pain, which is unusual because this is normally a bloodcurdling, painful condition.

Fibrocartilaginous Embolism (FCE)

This is when a small piece of cartilage enters the bloodstream and blocks the blood supply to the spine, causing swelling. It was also slightly perplexing that both of Murphy's back legs were affected — normally, this is a one-sided problem, with one good leg and one bad leg.

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Tumor

A tumor was certainly a possibility, but the symptoms should have appeared gradually.

Neuritis

This is a spinal cord inflammation, and the dog is usually sick and possibly feverish, none of which applied to Murphy, who was happily begging for treats.

Spinal Cord Hemorrhage

A blood clot can cause spinal cord damage, which is usually associated with trauma (which Murphy did not have) or problems with blood clotting.Murphy, on the other hand, had healthy pink gums and no signs of internal bleeding.

Murphy didn't seem to fit into any of these categories.

The Following Step: Tests to Determine When a Dog's Back Legs Are Weak

When presented with a dog whose back legs are weak, which test would most likely provide us with the answer?

In a nutshell, an MRI or CT scan.

• Both will provide an excellent image of not only the bone but also the nerves.
• This is superior to X-rays, which only show bone problems and leave the nerves in the dark.

This meant referring Murphy to a specialist center for a cutting-edge scan, and the dog's owners didn't hesitate and agreed right away.

After a few phone calls, I had a veterinary neurological specialist on the line.

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He was confident that Murphy's problem was a fibrocartilaginous embolism (FCE), which is a "Labrador thing," with the breed being especially susceptible.

FCE symptoms appear suddenly, and the dogs are not in pain. Fortunately, FCE has a good prognosis.Many dogs recover completely with excellent nursing care.

However, there was still a slim chance of disc disease, which could not be ruled out without an MRI scan.

I discussed this with Murphy's representatives, who, quite rightly, preferred that Murphy be seen by a specialist in case something else was wrong.

Keep an eye on this dog as she works to strengthen her back legs:

A Twist in the Tale

I received a preliminary report from the specialist about two days later.

Murphy had not one, but two slipped discs.

He'd had surgery to remove the discs and was recovering well; prompt action meant the damage to his nerves was limited, and he should recover well, fingers crossed.

Things don't always go as planned, and where possible, confirming (or ruling out) a hunch is the best policy. Keep that tail wagging, Murphy, and next time, how about something simple, like a snagged claw?

Please consult your veterinarian if your dog's back legs are weak.

If you have any questions or concerns, please contact your veterinarian, who is best equipped to ensure your pet's health and well-being. This article is provided for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.See additional information.

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