Cerenia Injection For Dogs Side Effects. Rarer side effects include lethargy, decreased appetite, diarrhea, allergic reactions, uncoordinated walking, and convulsions. For many, dogs are like another member of the family and rarely are left behind regardless of the destination.

Pain and swelling (at the injection site if injectable cerenia is given) The most common side effect associated with injectable cerenia is pain at the injection site; It does strike me as odd that 3 injections were administered.