I took my healthy 5-year-old indoor cat to the vet this morning. They wanted to draw her blood before she gets her teeth cleaned next week. When we got home I noticed one of her front legs was swollen. Is that normal or should I take her to the emergency room?
This is a great question that many cat owners ask-–thanks for sending it in. I know it’s alarming to see a swollen body part on your pet!
When your cat’s leg is swollen after a blood draw it’s likely due to blood leaking from the vein and into the space under the skin during the procedure. Healthy animals won’t have any major problems from this. The leg might be a bit sore for a day or two but the hematoma will gradually resorb.
Let me explain why this happens and what you can do to help…
How a cat blood draw is done
There are a few accessible veins from which vets or vet techs can collect blood samples from a cat.
- Jugular vein–large veins on the underside of the neck on each side of the Adam’s apple
- Cephalic vein–small vein on the top of each front leg
- Medial saphenous vein–small vein on the inside of each back leg
It’s nice when we can use the jugular vein because it’s faster to collect a larger amount of blood than using the small leg veins. But as you might imagine, cats are not always cooperative for this procedure. So we resort to using the small leg veins because it’s less distressing to the cat. (1)
Why a cat’s leg might swell after a blood draw
Cats don’t understand that they need to hold very still for a blood draw. It’s not unusual for cats to struggle a bit no matter how gently it’s done. When they move their leg while the needle is in the vein sometimes a little blood leaks out and collects under the skin. This is called a hematoma and it’s kind of like a bad bruise.
The person drawing the blood will apply pressure over the vein for a few minutes to stop the leakage. Plus the cat’s body quickly forms a clot to seal the needle puncture in the vein.
Once the blood is under the skin, the body slowly works to resorb it and the area returns to normal usually within a day or two.
Don’t forget to remove the bandage!
Sometimes, the vet clinic staff will place a small pressure bandage over the needle puncture site. This really only needs to stay in place for no more than 30 minutes to prevent continued bleeding.
I’ve had more than one cat who got a swollen leg because their owner did not remove the pressure bandage after they got home. The bandage can act like a tourniquet and cause the leg to swell below it due to poor circulation.
If you don’t think you will be able to take your cat’s pressure bandage off at home, ask the clinic staff to do it before you leave.
What you can do at home
Assess how your cat is doing
Take a calm, close look at your cat. Are they showing any other abnormal symptoms? Look for crying in pain and limping. Watch out for difficulty breathing, weakness and extreme lethargy.
If your cat seems normal except for localized swelling on their leg, it could be a simple hematoma.
Call the vet
It’s always a good idea to call the vet clinic where the blood draw was done and let them know what you’re seeing. They will let you know if you should bring the kitty back in for an exam. Every situation is different and it’s better to be cautious and check with the vet.
Monitor the swelling
Once you’ve gotten to this point, you should monitor the swollen leg for changes. Especially watch to see if the swelling is increasing or if new symptoms are developing. Report any new symptoms to your vet right away.
You can try applying a cold compress to the swollen area to help with pain if your cat will allow it.
Place a wet washcloth in a zip-top plastic bag and put it in the freezer for about 15 minutes. Apply the bag with the washcloth over the swollen area for only 5-10 minutes at a time. Don’t press too hard and don’t force it if your cat struggles.
When is it an emergency?
So when should you worry about a cat having a swollen leg after a blood draw? Look for the following:
- Severe limping
- Increasing swelling or continued bleeding
- Significant pain (crying, hiding, not eating, etc.)
- Labored breathing
- Extreme lethargy
- Persistent swelling after 48 hours
It’s not unusual for a cat to have a little localized swelling on their leg or neck after a blood draw. Most cats don’t seem to have significant pain from this bruise-like hematoma.
There are some health conditions that could cause leg swelling that is not related to a simple hematoma. Since each case is different, the best thing to do is call your vet’s clinic and ask for advice.
- Hunt, J. A., Hughes, C., Asciutto, M., & Johnson, J. T. (2020). Development and validation of a feline medial saphenous venipuncture model and rubric. Journal of Veterinary Medical Education, 47(3), 333-341.