Italy has produced talented film makers, but it's better known for producing cheap and lurid bits of gonzo sleaze. Now that's certainly not a product on which the Italians have a monopoly, but - rightly or wrongly - when you say things like "giant mutant guinea pig", my immediate reaction is going to be "Italian film".
Alas, Panic (or Bakterion as it was originally known; or Monster of Blood if you're from the US) doesn't really have much more than the guinea pig to offer when it comes to 'gonzo', and it's pretty light on 'sleaze' too. That just leaves 'cheap' which it certainly has in spades. And hey, Roger Corman built his sixty year career on 'cheap', so it can certainly work as a strategy.
The basic plot outline is simple enough: a secret experiment goes awry, transforming both the subject of the test (the guinea pig) and the scientist performing it, into mutated monsters. The pair get away unnoticed in the confusion, and the facility's owners do their best to gloss over the incident.
The authorities aren't buying it though and call in Captain Kirk (yes, that's really his name) to investigate the accident. Kirk will soon find himself pursuing a serial killer, as the mutated scientist rampages around murdering folks and drinking their blood. Normally, I'd expect the kill scenes to be big gore fests (they certainly would be if Dario Argento was making this movie) but this film tends to 'cut away' in the attacks. Which given how static and uninteresting most of the rest of the film is, means that there's not much to alleviate the boredom.
Other than this guy, I mean. We're supposed to be looking at him through a manhole in this picture.
Oohs a cute widdle giant mutant guinea pig then?
Alas, other than this one moment of unintentional hilarity, there's not much to recommend here. The script's hamfisted, the acting poor (to be fair, most of the dialogue is probably dubbed in in post), and the action non-existent. Not worth your time.