Guinea pigs can suffer from a number of skin parasites or infections. These can cause hair-loss and itchiness (pruritus) and require treatment. It is important to diagnose which parasite or infection is causing your guinea pig's skin lesions in order to treat them appropriately. In this blog I will run through the most common skin lesions in guinea pigs. Ringworm: Ringworm is not a worm but caused by a fungal infection, usually with a fungus called tricophyton mentagrophytes. Young animals are affected more often than older animals. Lesions are usually found around the head area and typical show hair loss, with crusting and scabbing. You will find that the hair falls out very easily at the edges of the lesions. If it is a mild case, it is usually not itchy. If the case is more severe, it can spread to other areas of the body and become itchy. This can result in the lesions becoming infected. The condition is zoonotic, meaning that lesions can spread to humans from the guinea pig. To prevent the transfer to owners, it is important to wash your hands after handling or treating you guinea pigs. If you notice similar lesions on your skin, please consult a pharmacist or doctor.

Ringworm in guinea pigs can be diagnosed by appropriate clinical signs and/or a fungal culture. All guinea pigs living together should be treated if one of their cage-mates has lesions. There are several different types of treatment available including washes, ointments and oral preparations. Treatment should continue for several days beyond the lesions resolving.

Lice: Lice are a type of insect living in the coat and skin surface of affected guinea pigs. The most common louse found on guinea pigs is called gliricola porcelli, another louse called gyropus ovalis can be found in some cases. Both of these lice are termed biting lice (which means they feed on surface skin cells), sucking lice are uncommon in guinea pigs (these feed by sucking blood).

Lice are very itchy, skin lesions occur as a result of this itching and include: hair loss, scabs and thickened skin. You will be able to see the lice in the coat of the guinea pig, usually around the rump or the back of the neck. They are about 1mm long and cream coloured. Diagnosis is by seeing the lice and/or performing a tape strip exam under a microscope. Lice pass from guinea pig to guinea pig easily, if they are in close contact; but do not pass to humans. Treatment is usually with topical insecticides and anti-inflammatories to control the itch and discomfort.

Mites: There are a number of mites affecting guinea pigs, the most common are trixacarus caviae (sarcoptic mange) and Chirodiscoides caviae. Trixacarus caviae is a mite that burrows into the skin, because of this they cause extreme itchiness and pain. The itch can be so severe that the guinea pig may start seizuring. Guinea pigs with this mite will commonly show hair loss n and the skin may become thick, yellow and crusty. Secondary bacterial infections often occur due to breaks in the skin from itching. The guinea pig may show generalised signs of illness due to the pain including lethargy, inappetance and weight loss. Treatment is usually with injectable antiparastic agents alongside pain relief. In addition, bedding will need to be thoroughly cleaned. Although not common, this mite can be transmitted to humans. Wear gloves when handling affected guinea pigs. If you notice lesions on your skin, please consult a pharmacist or doctor. Chirosdiscoides caviae are a non-burrowing mite and therefore produce very mild signs, and sometimes may not be associated with clinical signs at all. Unless they are causing clinical sign, these can remain untreated. If treatment is required, topical or injectable antiparastic agents can be used. Often, owners are concerned about white flecks in their guinea pig's coat. These flecks could be related to dry skin or they could be chirosdiscoides caviae. Neither are a significant cause for concern unless the guinea pig is itchy.

Owners often ask me about pain relief (analgesia) for guinea pigs. Sometimes pain in guinea pigs can be hard to assess and there is no universal pain scale in use for guinea pigs. Dogs, cats and rabbits have a universal pain scale that allow the veterinary profession to objectively assess the animal’s level of pain based on set criteria with a scoring system (i.e. 1-10, 1-5). This type of scale does not exist for guinea pigs as this is an area of research that needs to be developed.

Because guinea pigs are prey animals, they typically hide signs of pain. An observant owner, with a well-trained eye, can look out for changes in their guinea pigs, as well as the following signs:

· decreased mobility

· decreased appetite

· weight loss

· a hunched-up appearance

· teeth grinding (different from chewing)

· a fluffed-up hair coat

· vocalising (squealing, squeaking)

If you notice these signs, it is important to take your guinea pig to see a vet so they are not in pain. There are several pain relief options for guinea pigs and many of these are affordable. There is now a licensed anti-inflammatory, pain relief medication available for use in guinea pigs. This medication is effective and a good place to start for pain relief when treating guinea pigs who are in pain.

How a vet prescribes pain medication works under what is termed a prescribing cascade. This means that a vet starts with prescribing a drug that is licensed for that use, in that species first. Under the prescribing cascade, if such a drug is not available (or there are reasons for not using it) a vet can prescribe:

- either a medication licensed for that use in another species, or a medication licensed for a different use in the same species

- medicine licensed in the UK for human use

- medicine licensed in another country

It is important to understand that in order to obtain a licence, a drugs company has to satisfy several criteria to show that the medicine is safe and effective for use in that species, at a certain dose. The licensing process can be quite costly and this is potentially why there are very few medicines licensed for guinea pigs. Therefore, most medications for guinea pigs are prescribed under the cascade.

There are many safe options for pain relief in guinea pigs. Non-steroidal anti-inflammatories are thought to be more effective at higher doses and appear not to have the same possible side effects in guinea pigs, as they do in other species. These are the mainstay of analgesia in guinea pigs. There are several other pain relief medicines available to guinea pigs, including gabapentin, amantadine and tramadol. These can all be given in oral, liquid preparations. In addition, injectable opioids are effective and local nerve blocks can be used in some cases.

After taking your guinea pig to the vet, it is very important to monitor your guinea pig/s closely for continued or new signs of pain during their course of medication. If you feel your guinea pig is still in pain, please speak to your vet about adjusting the dosage or medication. Each patient/case may have a different response to the prescribed medicine and dosage.

Guinea pig poos can give you some indication of their their health. Guinea pigs are very talented at hiding signs of ill health due to the fact that they are prey animals. In the wild any signs of weakness or disease would result in their rapid demise. Being able to pick up on subtle signs that something isn't quite right could dramatically improve the chances of recovery from disease. The five main things you should make note of are faecal number, size, colour, consistency and smell. Changes in any of these parameters can be an indicator of change in diet, appetite, gut motility, hydration status and infections.

Number As herbivores guinea pigs are designed to eat and poo a lot, since their diet has relatively low nutritional value. A 'normal' guinea pig will produce up to 100 poos a day. This number is naturally lower in older or less mobile guinea pigs. If the number of faecal pellets drops below 50 a day it may be a sign that something is wrong. Reasons for lower numbers of poos can be reduced food intake or slowed gut motility.


Size can vary a little from one pig to the next, with large adult males sometimes producing pellets 1.5 to 2cm long (average is closer to 1cm). They should be rounded at both ends, smooth and plump. If the poos are very small it is often an indicator that food intake is too low. If they are tear drop in shape (ie pinched in at one end) it can be a sign of dehydration, or altered gut motility.


Normal faecal colour is dark brown. If the faeces are greener in colour and soft it is likely to be the caecotrophs (faeces that are produced following one pass of the gut, they are eaten directly from the anus to pass through the GI tract for a second time). Caecotrophs are not normally seen in the cage, as they are eaten straight from the anus. If they are noted it will be a sign that your guinea pig is struggling to eat them, this may be due to age and spinal or hip pain. In addition some guinea pigs will be seen chasing other guinea pigs to eat their caecotrophs. This is normal in young, weaning guinea pigs, in order to populate their guts with 'good bacteria'. It can be normal in older guinea pigs too, or may indicate a problem with gut microflora or a vitamin deficiency.


Normal guinea pig poos should be firm and well formed, with a slight glisten. If the poos are dry and crumbly it is an indication of dehydration. If the poos are soft and easily deformed it is often a dietary problem. An ideal diet contains 80% hay or grass, with an eggcup of pellets, and fruit and veg as a treat only. Fruit and veg does not need to be given every day and should be a treat sized portion (not a plateful). If the faeces are watery it is an emergency and you should take your guinea pig to the vets immediately, it can be a sign of infection, including clostridial infectious, which can be rapidly fatal even with aggressive treatment. Some older guinea pigs, especially boars, have a reduction in muscular tone around the anus. This can allow the development of faecal impaction in a sac like pocket by the anus. Faecal pellets build up in here and a fungal infection can ensue, it can also make it difficult to pass more faeces and for the guinea pig to eat it's caecotrophs. It is common requirement for owners of older boars to empty this sack of faeces on a regular basis. A video on how to do this can be seen through facebook:


Guinea pig poos should not normally smell. If they do it could be the caecotrophs that you're observing or a sign of infection.

Changes in guinea pig poos are rarely as a result of infection, it is much more commonly due to diet, inability to eat normally (teeth), or altered gut motility. If you are concerned that your guinea pigs poos are not normal seek veterinary advice.

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Derwent Valley Vets

Boat House Inn,

110 Dale Road,




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The Guinea Pig Vet's Consulting Times work on a two week rotation.

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Derwent Valley Vets are available to see guinea pigs during times outside of the specified hours listed for The Guinea Pig Vet.

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Out of hours emergency provision is provided by:

Vets Now at any of their surrounding clinics. In order to contact out of hours provision,

+44 01629 55666

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