At least, I’ve never seen an ad for a product that would delouse a dog or cat.
WAG. They do get lice, but the lice are specific to the species they are infesting and do not pose any pestiferous inconvenience to their human companions.
Did you really intend for this to be in GD? If you had in mind GQ, feel free to report my post to a mod and request a venue change.
Moderator’s Note: Yeah, not really seeing a debate here, so let’s let the Big Brains over in GQ take a crack at it.
They do, but it’s less common than ticks or fleas.
In fact, I don’t think I’ve ever seen a dog or cat with lice, or at least not so bad I noticed.
Maybe enough dogs and cats are in good health/kept in small enough groups that bad infestations are rare?
Will inquire.
I’ve seen products that kill fleas, ticks, and lice for cats, and I think also for dogs. I think if it kills fleas and ticks it also kills lice, but I might be mistaken? 
They do get lice, but lice infestation in dogs and cats is considered a problem of neglect (ie, the animal is in very poor bad shape and probably has some other nasties).
Different from ticks and fleas, which may prefer one species but can live in many others, lice are mainly species specific. Different animal species have their particular lice species.
The reasons you don’t see products being marketed specifically for lice control are:
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As said before, it is uncommon for regular well kept pets to have it, and if they do, they probably have a lot of other issues.
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Many of the major ectoparasite killers in the market (from the Avermectin family, at least), are also capable of killing lice. So if the veterinarian finds lice on a pet, they will use the same “tick and flea products” either at the same dose, or at a dose deemed effective for lice killing.
Zabali, an avermectin-based product (Revolution, Advantix-Multi, Advantix, Ivomec, etc.) will be effective. Frontline (fipronil) and others are not. I’m not familiar with the newer products(like Promeris).
Double post.
That’s what I had recalled, we had a problem with fleas last summer, we humans brought dog fleas in to the cats. 
Adding: We do try to use the flea and tick preventative, but had some emergencies come up. We had to borrow to go get the next round for them.
[gulp]
Including humans?
Of course including humans. This is good news BTW, as far as it goes. If your kid comes home from school having picked up head lice (or if your teen-aged son returns from Spring Break with pubic lice [that’s right, crabs; there’s no need to be squeamish]), you don’t have to worry about the infestation hiding out on Spot or Puff (or Scabbers) after you’ve successfully de-loused your offspring.
In a similar way, you cannot blame that you got lice from spending too much time next to Scruffy… 