Why is my cat walking funny and swaying after taking antibiotics?

If the clavamox didn't resolve the issue, I would bring him back in for additional exams such as neurologic examination, bloodwork, x-rays, etc to try and narrow down the cause. These can help rule out metabolic or infectious issues, injuries or joint problems, or neurological disease that could be causing his symptoms. If you weren't comfortable with your current vet, seeking out a second opinion in person or getting a referral to a specialist in your area may also be beneficial.

These are not typical symptoms for an upper respiratory infection. I would recommend that you have Pus re-evaluated by the vet. He should have a thorough physical and neurologic exam, and may need x-rays and blood work. There are many things that can cause weakness or inability to stand, but many of them have a poor prognosis. Unfortunately, we need more information to try to figure out what is going on.

Difficulty walking could be a sign of neurologic disease, and infection would be a concern for a cat Fluff's age. Some parasites like toxoplasmosis can cause neurologic disease, as can viruses like the feline immunodeficiency virus. Difficulty walking could also be related to trauma but this might be more obvious on an exam. If the labs are not conclusive, a referral to a neurology specialist might be recommended as sometimes advanced diagnostics like an MRI and/or spinal tap are necessary for a diagnosis. If she continues to eat and drink normally and does not seem painful I'd wait for test results to come back and discuss the next step with your veterinarian.

The fact that she responded indicates it was at least in part sensitive to the treatment. It is possible that there was a mixed infection with other viruses especially herpes or inflammation which has not been controlled. Further investigation and testing would be recommended in order to determine all of the factors involved

I wonder if maybe she has neurologic damage or did not heal after the panleukopenia. I would talk to your vet about blood work, a neurologic exam, and maybe referral to a specialist in internal medicine or neurology to determine what could be causing the shaking and loss of balance. Increased respiratory rate or changes in breathing sounds could indicate an upper respiratory infection, a nasal polyp, or possible scar tissue from previous infection.

Thank you for using Petco Pet Education Center, formerly Petcoach! The signs you describe can be caused by an irregularity in the spine - this may cause the bones to compress the actual spinal cord, damaging the nerves that are responsible for controlling the back legs and tail. A veterinary neurologist would be able to further diagnose the condition and propose a treatment plan, your original vet may be able to recommend one. I would be happy to take a look at x-rays or bloodwork and answer any questions you may have about them!

This is definitely concerning that he is having life-threatening complications. Laying on the side with front legs outstretched often indicates brain damage, which can happen when the brain is starved of oxygen, or severely damaged due to the infection. Without professional treatment, Nicky may not survive this. If there is an emergency veterinarian in your area, then I'd recommend taking him there as soon as possible to give him the best chance at survival. I'm really sorry to see this is happening to poor Nicky and wish I could help more, but there is really not much more that can be done outside of a veterinary hospital. If you have further questions or need further clarification, then you may consider having an online consult with one of our vets on Petco Pet Education Center, formerly Petcoach. This way, you can send unlimited pictures and have a text conversation with a vet. I hope that helps and Nicky pulls through this.