Please, PLEASE, never use carpet fresh!! Its NASTY!
The first step is to remove the source of the odor, take the cyclone off, blow it out if you can, then fill a sink or other suitable container with hot tap water. I also recommend the enzyme cleaner, the rancid smell is from the oils in the dog's fur and dander decomposing (I know, its nasty). Just submerge the whole cyclone in the hot soapy water. I'd recommend something that cuts oil and grease well, remember we are washing out oils from the dog's skin. Let the thing soak for a bit, then shake it around, scrub what you can with a brush, then rinse thoroughly. I'd also recommend washing the bin and also taking the power head and removing the brush roll, and completely cleaning it. You can carefully wash out the brush roll area and the passage/hose that leads to the wand, but DO NOT submerge the whole head. Let all of this dry for a day and then put it together. You'll likely still have some smell, I personally use an ozone generator, letting the machine suck that through for a few minutes/until there is no smell left.
You have an uphill battle trying to keep the smell away, as it will return as soon as a you get all the powdery pet dander up in the cyclone and filter and it starts to go rancid, the one and only solution to this is washing the thing out regularly, trying to cover or get rid of the smell without addressing the cause will just add obnoxious perfumes to the already noxious odor, I've seen it MANY MANY times here at work with machines customers bring in after trying to cover the smell with various things, they eventually bring it in for a proper servicing.