When Tess broke up with Dave she handed his engagement ring back, so it should not have been in a ring box in her drawer.
The show must have lost their continuity person and hired a writer that never watched the series. Surely Tess would have told Stevie that Dave called her by his dead wife's name Leanne in his sleep not to mention the nonsupportive cancer double mastectomy horror story in the car.
An animal autopsy is called a necropsy. Dave used the wrong word.
There is no vaccination for contaminated animal feed. Bad writing.