LICE (sometimes called "Running Lice")
Lice can cause scratching, loss of hair, and scabs, and are usually found round the ears, head, and neck, and rump. They are visible to the naked eye. The sores may be scabby and the skin, thickened, dry and scaly. Lice are easily treated with topical ivermectin or plain Advantage.
Lice, like mites, are generally considered host specific and need a guinea pig to survive. Most common is Gliricola porcelli (1 to 1.5 mm), the slender guinea pig louse and less common, gyropus ovalis (1 to 1.2 mm), the oval guinea pig louse. They are flattened insects with no wings and are considered biting lice -- they abrade the skin to obtain fluid. Gliricola porcelli are light colored (white to pale yellow), wriggly insects which can easily be seen moving through the fur near the skin and in heavy infestations, around the eyes. A third species of lice, trimenopon hispidium, are very rare; light infestations easily overlooked; heavy infestations cause alopecia and rough coat because of excessive scratching.
Lice seldom leave a living host and transmission usually occurs through direct contact with another guinea pig, from contaminated bedding or utensils, or from being carried by a person who has recently handled an infested animal, transferring eggs or lice from their clothing/person to the guinea pig. Bedding materials which have not been in contact with a guinea pig, such as hay or shavings from a feed store, will not contain lice. As with mites, weakened or young individuals will suffer the most.
Thanks to Stacy Hudon for her photo of a Gliricola porcelli louse (click on photo for larger image and Click HERE for head close-up). Thanks to PinkRufus for her Gliricola porcelli lice sketches.
Advantage (imidacloprid) is apparently a very safe and effective treatment for guinea pig lice. While plain Advantage is no longer available, Advantage Multi can be used to kill lice and will also kill mites. Bayer offers "kitten" size doses for animals 2 to 5 pounds in weight. They do not advise treating animals less than 2 pounds with their pre-measured pipettes.
An abstract of a 2008 study found at Pubmed, Use of a formulation containing imidacloprid and moxidectin in the treatment of lice infestation in guinea pigs, noted that guinea pigs remained free of lice 30 days after treating "with a single application of 0.05 mL of a solution containing 10% (w/v) imidacloprid and 1% (w/v) moxidectin indicating that this procedure is an effective treatment for lice infestations in guinea pigs".
Do Not Use Advantage II. Advantage II also contains an insect growth regulator (pyriproxyfen) which should not be used on guinea pigs.
Both Revolution and ivermectin will kill lice. Ivermectin works best on lice when it is used topically. This is because lice are biting insects, not sucking insects. Read more: Lice and Ivermectin. Ivermectin, a potent drug, is absorbed through the skin and requires accurate dosing to avoid serious side effects. Incorrect doses of topically applied ivermectin can cause death.Avoid flea and tick powders and shampoos -- many contain pesticides that are dangerous for guinea pigs..
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