Whether you are obtaining a guinea pig, or just checking your little pigs over each day, you need to understand what a healthy guinea pig looks like. This is not as detailed as a veterinary examination, but it should alert you to a potential problem that requires further investigation. The first step in your examination is to sit back and watch the guinea pigs for a while. As a prey species, guinea pigs will try to hide any signs of illness or pain that might attract a predator (the ‘masking phenomenon’).
They can’t keep this up for long, so be patient. Once you have watched them for a while, gently pick up the guinea pig and look them over in more detail.
Guinea pigs are social and love food; they should be interactive with their companion guinea pigs and their owners (once they have settled into their home). They are moving almost constantly, although regularly they stop, check out their surroundings, and then move on. They call out to each other and to you as they move around. They should be seen to be eating much of the day, constantly chewing hay and grass, and nibbling on their vegetables.
Droppings and urine
Guinea pigs produce a large amount of faeces every day. Their droppings should be small and well formed in a tear drop shape and they vary from light yellow brown through to very dark brown depending on their diet. Urine colour varies depending on the amount of calcium they have eaten as this is excreted in the urine. The colour can vary from pale straw coloured, to white and reddish-brown depending on diet.
Body condition and weight
Most healthy guinea pigs weigh 800-1000g and are well covered with a thin layer of fat and muscle. The spine and pelvic bones should not be obviously prominent. Very thin guinea pigs often weigh less than 700g, their ribs are visible, and their spine and pelvis stand out. Obese guinea pigs weigh over 1000g, and have a very round, rotund body shape.
Coats vary in length and type but should be shiny and well groomed. There should be no bald areas (apart from the inside of the front feet and behind the ears) or thinning of the coat. There should be no matting of the hair running down from the chin to the breast muscles. The guinea pigs should not be scratching or chewing themselves excessively.
Head and face
A healthy guinea pig has bright, alert eyes with no signs of cloudiness, discharge, or redness, and they should have clean noses and ears. There should be no lumps on the face or lower jaws, or at the base of neck. Try to get a look at the front teeth as well. They should not be overgrown and should be well-aligned. Also, check for wet or matted fur on the chin.
Observe the guinea pig’s breathing. It should be quiet and not laboured, with no wheezing, clicking, or gurgling noises.
Feet and legs
A healthy guinea pig should walk without limping or holding up or dragging one or more legs. None of the joints should be swollen, and the pads on the soles of the feet should soft pink. There should be no reddened areas, swellings, scabs, or sores on the feet.
If you do notice any signs that your guinea pig is not entirely healthy, you should talk to a veterinarian who has experience with guinea pigs as soon as possible. Due to the ‘masking phenomenon’, a guinea pig who is showing any sign of being unwell is often very unwell as they are so sick they can no longer hide their illness.
Quesenberry K, Orcutt C, Mans C, Carpenter J (2021) Ferrets, rabbits, and rodents: clinical medicine and surgery, 4th ed. Elsevier