I doubt an eight year old had low blood sugar. Her medication was my first thought. I found this under possible side effects with Metacam:
* All NSAIDs are removed from the body by the liver. If the patient’s liver is not working normally due to another disease or if the patient is taking other drugs that are also removed by the liver, it is possible to “over work” the liver and exacerbate pre-existing liver disease. If there is any question about a patient’s liver function, another class of pain reliever should be selected. Meloxicam (Metacam) - VeterinaryPartner.com - a VIN company!
Have her liver values always been normal in the past?
I would ask your vet for Tramadol for pain. That is the safest medication. My Lady can take it for her arthritis and she has epilepsy, diabetes, liver disease and a heart murmur! It is also very effective.