He added: "It's horrific and I had absolutely no idea there was such a thing as fake pet medication." Alongside this, the PDSA urges pet owners to source prescriptions from reliable companies listed on the Veterinary Medicines Directorate . While legitimate medications play a vital role in keeping our pets healthy, fake medicines can cause severe harm or even be fatal. Recommended reading:"We always recommend that you only give your pet medication which has been prescribed by your vet. "If you are concerned about your pet, or suspect they are reacting badly to any medication, contact your vet immediately."