Mange Mites Trixacarus caviae
Mange mites can kill.
Death can occur due to severe dehydration from the increasingly larger sores and from failure to eat, because of their extreme pain and discomfort. In a healthy animal, the mite may be dormant for months or years, becoming a problem in a pregnant guinea pigs or one subject to illness or stress. The most serious infestations occur in the young and ill older animals subject to stress and poor environmental conditions, usually on the trunk. The response in healthy animals is less severe, perhaps due to grooming or suppressed immune response (Harkness and Wagner).
These microscopic mites burrow under the skin and cause severe pain. You may notice scratching, biting, hair loss, and in serious cases, seizures. Severe infestations can be life threatening. If you suspect one of your guinea pigs have mange mites, treat them all (they can be carriers while not showing signs) as soon as possible. Ivermectin is the treatment of choice. Multiple doses are necessary because ivermectin does not kill the eggs. Read more about ivermectin.
Mange mites are not zoonotic. On rare occasions they may cause some temporary itchiness for sensitive people but cannot reproduce or live on humans.
The Sellnick mite, (Trixacarus caviae (a burrowing sarcoptid mite) is a member of the arachnid family. Transmission occurs primarily through direct contact with infested animals although eggs can be carried to them inadvertently. Mites will seldom leave the host unless brushed onto the bedding or as a result of overpopulation or the death of the host. With no host, they will usually die within 3 weeks. However the eggs, which are laid in burrows in the skin, may survive independently for long periods of time. Harkness and Wagner believe some early reports of infestation of guinea pigs by Sarcoptes and Notoedres mites may have actually been caused by the Trixacarus mite, since they can easily be confused.
Find images of ectoparasites at www.radil.missouri.edu.
Click on photo at top of page for larger image.
Photograph contributed by Kat.
Signs: These species specific microscopic mites cause unbearable itchiness for the animal and can result in thinning and/or patchy loss of hair, scurfing of the skin (may resemble dandruff) and eventually, open sores as a result of extreme scratching and biting which aggravates the hair loss. Scratching an area of skin infested by mites by hand may produce such pain and irritation in your guinea pigs that it looks like it's having a fit. A guinea pig suffering from mites may become less friendly and be reluctant to interact with its owner.
While skin scrapings may confirm mites, scrapings are frequently omitted because they are so unreliable (see MISDIAGNOSIS below). Often a vet will administer ivermectin in the presence only of itching and hair loss, treating for other conditions such as fungal infections in the absence of improvement. It is important to note that your guinea pig may be suffering from more than one condition.
MISDIAGNOSIS: Occasionally a vet will completely misdiagnose a mite infestation. Ciaytee's vet ruled out mites when they could not be found in a scraping. He treated for fungus and yeast infections, sent off cultures, did a skin biopsy, and felt he was exploring every possibility. Her pet had to go under anesthesia twice -- once for a chem panel and once for the biopsy. All this time her guinea pig (who had lost 1/3 to 1/2 of his hair) was in great pain, with sores, and rather than improve, continued to get worse over several weeks. She finally suggested treating with ivermectin in case it was mites. The turn around was almost immediate. Check Guinea Lynx forums for a detailed account of her experiences.
Mange mites can kill.
Treatment: Mite infestations are generally treated with ivermectin by injection, orally, or topically (usually placed on the skin behind the ears because the fur is so thick). Two or more doses spaced 7 to 10 days apart are required. Ivermectin appears to be safe used on pregnant guinea pigs but is best not used on guinea pigs under 12 ounces (approx. 340 grams). This drug must be administered in the correct dose to avoid serious adverse reactions and possible death. A good exotics veterinarian should be familiar with the drug and know what doses are considered safe for guinea pigs. Seeing a competent vet will assure that this medication's use is indicated and that it is appropriately administered. A vet may also provide topical treatment for open sores and infection caused by scratching and for crusty skin and other complications related to the infestation. Diazepam can help control itching. Steroids may also bring relief to a guinea pig in such pain it is seizuring but must be used with caution. Cut the nails back to minimize further damage from scratching.
Ivermectin is administered by a formula specifying the dosage in milligrams per kilo of weight for the individual species. Therefore it is essential to know the weight of the animal to be treated, and the dosage in mg /kilo for that animal. Your vet should be able to find medical references to determine the correct dosage.
When mites are properly diagnosed, all your guinea pigs will need treatment and their living quarters must be thoroughly cleaned. Avoid future infestations by quarantining and treating new animals if suspected of being carriers and practicing good husbandry. Some breeders will routinely treat new guinea pigs in quarantine (since they can carry mites while showing no signs) rather than risk reintroducing mange mites to a whole herd of guinea pigs.
Alternate treatment: Some pet owners have had good luck with Revolution (Selamectin). A single dose applied topically kills both mange mites and lice. Read more about Revolution in the section on Antiparasitics.
Avoid flea and tick powders, sprays, shampoos, foams, gels and wipes -- many contain pesticides that are dangerous for guinea pigs. Read the ingredients. Some of these products have caused death. If your pet has mites, USE IVERMECTIN. When used according to directions and dosed carefully, it is a much more effective and safe product.
Itchy and Scratchy (pictured above) arrived at Orange County Cavy Haven in excruciating pain with severe mites. Steroids, body-wraps (to prevent self-mutilation), and lots of love were required to pull these two guinea pigs through. They lost almost all their hair before they started healing.
Photos by ChunkyPiggies.