Guinea pigs are hosts to a number of different parasites, some of which are normal commensals on the skin of healthy guinea pigs, some cause significant health issues, and others are even transferrable to humans (known as zoonotic)!

Any guinea pig of any age or sex can contract parasites. Juvenile or young guinea pigs with an underdeveloped immune system, or those that are immunocompromised due to underlying illness, are at greater risk of developing clinical disease from parasite burdens. Conditions that cause excess stress such as overcrowding, poor hygiene and unsanitary living arrangements, poor ventilation, pregnancy and lactation, inappropriate diet, hypovitaminosis C (low vitamin C), and various medications or illness can also predispose to clinical disease of parasites.

In order to prevent parasite burdens in your piggie herd, we recommend quarantining any new guinea pigs that are being added to your family, and monitoring them for any signs of illness before introducing them to your current herd. It is important to keep a clean and sanitary environment, provide ample space to move around, and supply an adequate and nutritious diet which includes vitamin C supplementation (high quality pellets and fresh vegetables daily). Visit our Care Guide for a list of high vitamin C vegetables. 

Below are some of the most common parasites that affect our companion guinea pigs in Australia:

Mites: 

There are two primary species of mites that are hosted by guinea pigs, Demodex caviae and Trixacarus caviae. Demodex are commensal mites that inhabit the skin of many normal and healthy mammalian species. Most of the time the host animals are asymptomatic and the mites do not cause an issue, however they have the potential to become pathogenic during periods of stress or in animals that are unwell or immunocompromised.

Trixacarus caviae are the most common type of parasitic condition of guinea pigs, and regularly display signs of clinical disease. Outbreaks are precipitated by stressful events, and can spread very quickly throughout a herd either by direct contact with infected guinea pigs or through contact with communal objects and bedding.

Mites are extremely small parasites and live burrowed underneath the skin and within the hair follicles, so are rarely seen with the naked eye. Guinea pigs that are infested with mites will become extremely itchy and irritated, spending a lot of time scratching, chewing or rubbing their body on objects. Due to excessive scratching and self-trauma, guinea pigs will often develop secondary wounds and excoriations of their skin, resulting in fur loss, wounds, scabs and crusts, some of which may bleed. Secondary bacterial infection is a common sequalae to these lesions. Lesions normally start around the head/neck region, however if not treated will gradually spread over the back and down the legs.

Some guinea pigs that are severely impacted, may develop seizure like behaviour especially when touched, which can be life threatening and require emergency veterinary care.

Treatment of mites usually involves confirmative diagnosis by your veterinarian who will likely perform a skin scraping test and identify the mites underneath the microscope. Your veterinarian will then prescribe topical, injectable or oral medications to treat the mite infestation, as well as any other secondary conditions that have developed such as bacterial infections, seizures, or underlying illnesses causing immunocompromise.  If your guinea pig is suspected to have mites, it is important not to wash them as this will cause the mites to burrow further underneath the skin, worsening the condition.

Ringworm:

Ringworm, unlike the name suggests, is not a worm at all, but in fact, a fungal infection of the skin. Ringworm is a zoonotic disease, meaning it can be spread to humans, and care should be taken to wear gloves and perform good hygiene practices when handling infected guinea pigs. ‘Ringworm’ is the common name given to fungal species known as Dermatophytes. These fungal spores are readily found in the environment, and are opportunistic pathogens usually only causing illness in young or immunocompromised animals. Animals that are experiencing stress due to underlying illness, immunosuppression, overcrowding, poor sanitary environment, poor nutrition, pregnancy or parasite burdens are at greater risk of displaying clinical signs of ringworm.

Guinea pigs that have ringworm usually have one or more round, scaly, hairless lesions over their body, commonly near the eyes, ears and nose (however can be anywhere over the body).

One of the most important aspects in treating and reducing the spread of ringworm is to reduce the number of infectious spores and fur in the environment. This involves thoroughly cleaning and disinfecting all parts of the housing environment, cleaning all bedding, and quarantining any affected animals.

Some lesions will be self limiting and resolve on their own, however more severely impacted guinea pigs may require topical or systemic therapy to get on top of the infection. Malaseb shampoo is a great medicated pet shampoo available over the counter and can be used to treat fungal infections such as ringworm. It is important to note that Malaseb shampoo requires a 10 minute contact time before being rinsed off to effectively kill the fungal spores, and should be used about twice a week until the infection has cleared. Some guinea pigs can become stressed during bath time and get hypothermic (cold) during the 10 minute contact time whilst wet, so bathing guinea pigs is not always recommended. Occasionally systemic anti-fungals are required which can be prescribed by your veterinarian.

Image credit: Guinea Lynx / Lindsaymarie.

Worms:

Intestinal worms are very uncommon in guinea pigs, and they do not require regular worming like many other domesticated companion animals such as cats and dogs. Worming for intestinal parasites is generally only recommended if a parasite burden has been confirmed by your veterinarian, which can be done via a simple faecal test identifying the presence of worm eggs. If you suspect your guinea pig has worms or has signs of diarrhoea or GIT upset, we recommend collecting some poop pellets and booking a veterinary consultation.

Protozoa:

Another family of parasites that inhabit the gastrointestinal tract of guinea pigs are protozoa – these are small living organisms that may live undetected, but when under stress, can cause severe illness. Young animals are most at risk of becoming unwell due to these parasites, and are commonly infected from a young age when an asymptomatic sow sheds the parasites into the environment for her babies to contract.

One of the most common and pathogenic species of protozoa in guinea pigs is Eimeria cavia, and causes a disease commonly known as ‘Coccidiosis’. Eimeria species are transmitted via the faecal-oral route, meaning the organisms are shed in guinea pig poop, which is then ingested by another guinea pig. Some animals will remain asymptomatic, however others will develop signs of diarrhoea, dehydration, lethargy, weight loss, anorexia, and in severe cases, death.

If you notice any of the above clinical signs in your guinea pigs, especially diarrhoea, we recommend collecting a faecal sample and booking a consultation with your veterinarian. Your vet will be able to perform a simple test on the faeces and prescribe special medication to kill the parasites. We recommend testing or treating each guinea pig that has come into contact with a positive animal as healthy guinea pigs are able to shed the organisms infecting those more vulnerable.