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Is morphine causing my dog's hind leg weakness and loss of appetite?

Updated on September 23rd, 2025

Pet's info: Dog | Airedale Terrier | 9 years and 10 months old

I have an 11 y/old Airedale with CKF. Unfortunately it has been complicated by hip and knee arthritis pain. recently, 7 days!, his stiffness has gotten worse so I have been giving him morphine for the pain his vet started laser on his hips/knees, Thu and Sat, but after the second one he now can't use his back legs to push up, I have to lift him, but he only takes a few steps then lies down again. He hasn't eaten since Friday night but still drinking. Could morphine be at fault?

3 Answers

Most Helpful Answer

Destini R. Holloway, DVM

Answered By Destini R. Holloway, DVM

Veterinarian

Published on October 30th, 2016

Poor guy. Morphine wouldn't cause lack of appetite nor would it cause worsening of his debilitation. It is likely it isn't enough therapy to overcome the advanced stages of his osteoarthritis. Especially since morphine is strictly a pain management medication and doesn't help with inflammation, joint fluid, or cartilage repair.
He likely would benefit from more advanced therapy such as Adequan (GAG) injections, joint supplements (Dasuquin) or even physical therapy sessions can help provide him more mobility. His lack of appetite is quite worrisome however and I would highly recommend getting his kidney values rechecked to make sure he doesn't need further treatment to stabilize him first. Because the inability to move could also be caused by generalized weakness due to his underlying kidney condition.
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Related Answers from Veterinarians

  • Answered By Andrea M. Brodie, DVM

    Veterinarian

    Morphine only works for a short time before the dose has to be repeated. Morphine can cause nausea, and can cause your dog not wanting to eat. Buddy is obviously in great pain, so your veterinarian should prescribe Buddy some pain medication (NSAIDs would not be recommended due to the CKF, however Tramadol and Steroids could be prescribed, in really serious cases he could also get a Fentanyl patch). Please see your vet and discuss the pain issue with your veterinarian. He should be willing to prescribe pain medication while he is laser-treating your dog's joints.

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  • Answered By Jennifer Summerfield, DVM CPDT-KA

    Veterinarian, Certified Dog Trainer

    Poor Buddy! I'm sorry to hear that he's having so much trouble. In my experience, rear limb weakness is not a typical side effect of morphine. Common side effects of this drug in dogs can include vomiting, restlessness or confusion, drowsiness, and sometimes even respiratory depression and lowered body temperature at high doses. But I would not expect to see just weakness in the rear legs, specifically. This could be happening because he is weak in general and doesn't feel well, or it could be that the arthritis is progressing to the point that it is becoming difficult for him to use his rear legs. If the morphine is keeping him comfortable, I would continue it through the weekend and have your vet check him first thing on Monday if possible to see what may be going on.

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