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Top 4 Causes of Hair Loss in Guinea Pigs

hair loss in guinea pigs

Hair loss in guinea pigs can be scary. Luckily, whether you’ve noticed excessive shedding or obvious bald spots, the top causes of hair loss in guinea pigs are actually pretty easy to diagnose and treat. But first, let’s bust a few myths. Guinea pigs do not lose hair with old age. And those bald spots behind the ears? Totally normal. All pigs have them.  Ok, let’s carry on.


Parasites are gross, annoying, and inconvenient, but don't worry ... they won't spread to you or other types of pets. These species-specific uninvited guests usually come from direct contact with another guinea pig that already has mites. They can also be spread through indirect contact, such as ​from bedding or clothing that has been tainted by the insects or eggs from an already-infested guinea pig.

Mites can't be seen with the naked eye, but their symptoms are fairly obvious. They can cause extreme itching, dandruff, skin irritation and scabs, and even seizures. Microscopic mites can be hard to spot, even through skin scrapings. The vet will likely diagnose the guinea pig based on symptoms alone (itching, hair loss, skin irritation, etc.)​

Bathing won’t cure mites, and can even make irritation worse and treatment more difficult. The most common medicine for both mites and lice is ivermectin, which is super safe. Ivermectin does NOT kill the eggs of lice or mites, so the treatment must be repeated at least once about a week later. For severe cases, the vet may even recommend a third treatment 7-10 days after that. Revolution is a chemically similar prescription product that can be given as an alternative. Revolution doesn't need to be repeated as frequently as ivermectin, and may provide protection for a full month.


Parasites aren't the only cause of dry, itchy skin and hair loss in guinea pigs. If treating for parasites doesn't resolve your guinea pig's discomfort, there may be other issues at play. Guinea pigs can suffer from fungus, like ringworm. Fungus can cause bald patches, scaly skin, and hair loss. Ringworm commonly starts around the head area, unlike mites, which often presents as a “V” shape on the back. A vet will be able to tell the difference, and will likely recommend an anti-fungal cream or shampoo, or give oral medication for severe ringworm outbreaks. Clotrimazole and miconazole creams are safe for guinea pigs.

In guinea pigs, most ringworm infections are caused by Trichophyton mentagrophytes. Ringworm can be caused by a few different species of fungi; Microsporum canis is more common in dogs and cats, for example. Regardless, it’s a good idea to practice good hygiene when treating a guinea pig with ringworm, as it can spread to other animals and humans in the household. Kids can be especially susceptible. Cleaning and sanitizing the guinea pig’s cage, accessories, and environment is essential to prevent ringworm from spreading.

Ovarian Cysts

Ovarian cysts plague more unspayed female guinea pigs than not after three years of age. Not all girlies will show signs or have problems. For the unlucky ones, symptoms include bilateral hair loss on the flanks, crusty nipples, and moody behavior (like mounting cagemates or acting irritable). The hair loss is caused by hormones out of wack, so these guinea pigs might act like they are in heat 24/7, rather than the normal day or two every two weeks.

Normally, spaying a guinea pig is the recommended course of action. However, not all seniors are ideal surgical patients – and, of course, seniors are usually the ones with this issue. Talk to your exotic vet about alternative treatments and how to monitor your ladypig if surgery isn't a good option for her. Draining cysts or using hormonal treatments can also provide relief from bothersome symptoms in some instances.


Hair loss that isn't falling out at the root may be self-inflicted. Your guinea pig may "barber" himself as a result of pain or stress. Check the bald areas for lumps, swelling, or signs of tenderness below. Older pigs may barber themselves as a reaction to pain from arthritis or tooth problems.

Your guinea pig’s pals may barber him too as a display of dominance or even bullying. If one guinea pig seems to be pestering other more than usual, you’ll want to keep an eye out for the picked-on pig becoming distressed, hiding more than normal to get away from his roomie, or being discouraged from his share of food and water.

While these are the most common causes of hair loss in guinea pigs, other potentially serious diseases can produce similar symptoms. Always pay a visit to your exotic vet if hair loss persists or you can’t identify the root cause.

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