Guinea pigs can come down with mites much like any dog or cat. Mites are microscopic parasites which burrow into the hair shaft of the animal to lay eggs. When the eggs hatch, they crawl out and proceed to feed off the animal. Needless to say, this is very itchy and unpleasant for the pet and often results in hair loss. There are prescription treatments for mites, and if the case is extremely bad they are the only way to go. The vet should also be seen if the guinea pig is older or has other health problems. Even if you merely suspect mites, the Neem oil will not cause any problems to the pet, but help with moisturizing the hair shaft and skin.
Step 1 - Neem Oil
Neem oil is used in many countries as a natural insecticide. It is also harmless enough to be used medicinally and as a flavoring in foods. Unlike Tea Tree oils which can be lethally poisonous at too large a dose, Neem oil will not hurt your pet even if large quantities are ingested. Unrefined, or raw, Neem oil can be purchased at most any natural marketplace for under 10 dollars. You only need a small amount. On low heat, melt the Neem oil and carrier oil together at a ratio of 1 part Neem to 4 parts carrier oil. If there are patches which seem a bit more severe, small amounts of straight Neem oil can be applied directly.
Step 2 - Rub Down
Rub the entire guinea pig down with the mixture of warm oil. Be sure you test the oil for temperature before applying. Do not merely cover the one place where the guinea pig has had a break out. The mites can transfer on the pet to untreated areas. Neem oil will also kill not only the live mites, but larvae and eggs as well so don't be skimpy. Allow the oil to stay on the guinea pig for 48 to 72 hours.
Step 3 - Rinse
Do not allow the oil to sit on the skin for longer than 72 hours, as it can become an irritant. Thoroughly wash the guinea pig with the medicated shampoo. Using the kitchen sink sprayer or a shower wand can quickly work to make sure the oil is removed, the scalp is thoroughly rinsed, and no shampoo residue exists.
Step 4 - Clean the Cage
Mites can live up to 2 weeks without a host. If your clean guinea pig goes back into a mite-infested cage, the problem will only persist. Remove everything from the cage. Any cloth items should be washed and dried in the hottest temperatures possible. Add 1/2 cup of Borax to the wash water along with the soap. All plastic or metal accessories and the cage itself should either be soaked in Borax water or run through the hottest dishwasher cycle possible. Return cage to normal with clean shavings.