Q: My one-year-old female cat received two injections in the rear to treat an insect bite. The first injection contained an anti-inflammatory medication and the second was Benadryl. The veterinarian at the emergency clinic said that the Benadryl would burn, and my small cat screamed when it was injected.
When I got her home, her back leg on the side of the injection did not work. It just dragged behind her. The next day, she was able to get the foot under her to walk on it and that has been it for progress. She is still quite lame. My personal veterinarian suspected the mobility issue was related to nerve damage and thought the leg would be fine within a month’s time. Three weeks have passed and still no improvement in her gait. What do you think happened and will she ever be able to walk normally again? – Nancy Norton
A: Dear Nancy: Each time we administer medication to a pet, there are always concerns about potential side effects. Local reactions are occasionally seen after the administration of any medication. Swelling and pain, bleeding and even cancer formation are possible.
Running down the hind leg is a major nerve called the sciatic. This nerve is located between two large muscles. Deep injections could place medication near the sciatic nerve, and swellings from the medication may injure the nerve. If the cat jumps at the wrong moment, even the needle itself may damage the nerve.
Your description of dragging the leg suggests that sciatic nerve injury may have occurred. Your doctor can perform specific tests for sciatic nerve damage. If the veterinarian’s examination is not consistent with a sciatic nerve injury, then something else is going on. A consultation with a board-certified veterinary neurologist would be warranted.
Many injection injuries do improve with time, however. I recommend waiting at least six to eight weeks. If there is no improvement at that point, scar tissue may be surrounding the nerve and surgical exploration may be indicated.
In the meantime, physical therapy to protect the limb and maintain normal range of motion in the joints is important. You should flex and extend the limb 30 times or so several times a day.
Michael Stone, DVM, ACVIM
Clinical Assistant Professor
Cummings School of Veterinary Medicine at Tufts University