There’s a lump or bump on the left side of my cat’s neck, noticed about a week ago. What could it be? It reacts when I touch it.

A lump on a cat’s neck may be caused by unabsorbed medication. Vaccines are usually given by subcutaneous injection, and when the drug isn’t fully absorbed a swelling can appear. You can observe for a while and apply a warm compress to the bump; it will usually gradually subside. If the cat was recently vaccinated or given an injection, this is very likely the cause.

In addition, a neck lump could also result from swollen lymph nodes or a skin abscess, which requires a prompt visit to a veterinary clinic for diagnosis and targeted treatment.