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Advice Mites and Lice and Fleas, Oh My!

Guinea Pig with Bad Case of Mites.jpg

What kind of bugs does my pig have?​

Itchy piggies can be mighty unhappy. While there are some skin conditions that can cause itching, the most common cause is parasites -- lice and mites. Fleas can also affect guinea pigs.

How does your pig get parasites? It depends. They've all got mites, all the time. Every living thing has mites. But they're usually not bad enough to cause problems. It's only when there's an outbreak severe enough to cause itching that they need treatment.

Lice, on the other hand, can be transmitted from another animal, or from infected bedding, or other materials. Fleas generally ride in on other pets in the home that are allowed to go outside.

You and your family can't "catch" any of those parasites from your pets. They're all specific to a particular species, and they'll only set up housekeeping on that species. They may bite another species if they're visiting, but it's a one-off thing.

The Bugs​

  • Lice
    It's pretty easy to identify lice. Their eggs are called nits and are about the size of a small grain of rice. Lice lay the nits on a hair shaft, and they're stuck like glue. You can't flick them off with your finger -- you have to pinch the nit between your fingers and slide it off the end of the hair. If the pig has enough of them, you can see the live lice running around.

  • Mites
    Mites can be harder to diagnose. They're microscopic in size, and burrow into the skin. They can't be seen with the naked eye (except ear mites, discussed below). Of lice and mites, mites make the pigs more miserable.

    Guinea pigs, like all animals, scratch occasionally, and that doesn't necessarily mean your piggy has parasites. But insistent scratching and hair loss usually indicates parasites, probably mites. Severe infestations can cause seizures and even death.

    One classic sign of mites is a V-shaped hair loss pattern on the pig's flanks, with the point of the V closer to the head and the arms of the V closer to the rear end. That's because the pig is biting at the itchy places, but that's the only place it can reach with its teeth.

    Don't bathe a pig that you suspect has mites. The water drives the mites crazy, and the mites drive the pig crazy.

  • Ear Mites
    The same mites, Psoroptes Cuniculi, infest both rabbits and guinea pigs. They're large enough to be seen, and cause the animal to scratch insistently at its ears. The treatment is the same as for other mites.

  • Fleas
    Fleas, like lice, are visible and can be seen moving on the pig. They'll run around, but they'll also jump.

    You can often identify fleas by flea dirt, even if you can't find the bugs themselves. Flea dirt is tiny black dots of poop, mostly dried blood. Sometimes, if you put flea dirt in a drop of water, you can see the red color. It's often found around the groin, the tail, and up the back.


  • Lice and Mites
    Severe infestations may require a vet visit, but usually, you can treat for parasites yourself. Be aware that a vet will probably want to do a skin scraping to determine if your pig has mites. That's painful for both the pig and your pocketbook, and a negative result does not guarantee that the pig doesn't have mites. The safest thing to do if your pig itches is to treat for mites with ivermectin.

    We don't recommend powders and sprays for parasite treatments. Guinea pigs groom themselves by licking and may ingest pesticides that are dangerous for them. Their digestive systems are easily upset, and it's best to avoid chemicals that can cause problems.

  • Ivermectin
    Ivermectin treats many kinds of parasites, including lice and mites, but NOT COVID-19! It can be given by mouth, by injection, or topically (putting it on the skin). The oral and injectable kinds of ivermectin can be applied topically, but the topical preparation can't be given orally or injected.

    Ivermectin is a strong drug, and you must be very careful not to overdose your pig.

    Pigs over 340 grams can be treated with ivermectin. Pups who weigh less than that can take kitten Revolution, which requires a prescription from a vet in some countries (including the U.S.) but not in others.

    The easiest ivermectin preparations to use are the .5% pour-on or 1% injectable strengths. Either can be purchased from places like Amazon, Valley Vet, or other veterinary medical supply stores. Local feed stores usually carry very concentrated forms of ivermectin, such as equine or bovine wormer pastes or pour-ons. A small tube or bottle of either of those will treat an adult horse or cow, and it is very difficult to dilute them enough to be safe for guinea pigs.
    • To treat your pig, you need a 1 cc (1 ml) syringe, the ivermectin, and the weight of your pig (in grams). Do NOT use an insulin syringe -- the units are not the same, and you'll underdose the pig.
    • If you have the .5% solution, the dosing chart is here: https://guinealynx.info/topical_ivermectin_pour-on.html.
    • If you have the 1% solution, the dosing chart is here: https://guinealynx.info/topical_ivermectin.html.
    • Draw up the ivermectin in the syringe -- it will only be a tiny amount, not nearly a whole cc. Put it on the bald spot behind the pig's ears, fold the ears over, and massage it in.

    Treat all your pigs once a week for at least three weeks, four if it's a bad infestation. It takes at least three treatments, a week apart, to hit all the life cycle of the parasites

    If one of them has parasites, they've all been exposed.

  • Advantage
    Plain Advantage is off the market, and if you find it, it's likely too old to be effective. Advantage Multi is used instead. Do NOT use Advantage II -- it has an insect growth regulator (IGR) that is dangerous to guinea pigs. It requires a veterinary prescription.

  • Revolution
    Revolution is an ivermectin-based product that also requires a prescription. It is most frequently given in the kitten strength to guinea pigs that are too small (less than 340 grams) to be dosed with regular ivermectin.

  • Beaphar
    Beaphar SpotOn products are more often used in the U.K. than in the U.S. There are frequent complaints that it does not work well, and the available dosages are smaller than recommended doses for the weights of the animals. Regular ivermectin gives much better results.

  • Fleas
    Fleas don't seem to be as susceptible to ivermectin as lice and mites. Your best bet is to see a vet for a topical treatment such as Revolution or Advantage Multi. Do NOT use Advantage II -- it contains an insect growth regulator (IGR) that should not be given to guinea pigs.


About the author
Billie Patterson is a top guinea pig expert and has been a member of the Guinea Pig Cages site since 2009. She's a well-known and respected moderator here and also a long-time member of the Guinea Lynx forum. She's beenthe most active contributor of solid guinea pig advice anywhere for many years.

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Billie Patterson
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