Guinea pigs are small and fragile animals, so it is important to monitor their weight and examine them frequently. Being prey animals, they hide any signs of illness for as long as possible, making it more difficult to detect if they are sick. Here is a list of things you should keep an eye on:
Weight: It is important to keep track of a guinea pig’s weight as weight loss can be one of the first indications that something is wrong. You can use a kitchen or other small scale to weigh them in either pounds and ounces or in grams. Guinea pigs weigh on average 1.5-2.5 lbs (680-1130g).
Musculoskeletal: Check your guinea pig’s overall body for abnormalities. Head-tilt can be a symptom of an ear infection or other issue and should be addressed by a veterinarian right away. If it is not addressed it can cause permanent damage.
Eyes: Check your guinea pigs eyes for signs of infection such as discharge or cloudiness.
Ears: Check for excess wax or dirt and clean with special ear cleaner if needed. Never stick anything into the ear canal. Also check for other irritation or mites.
Nose: Make sure the nose is clean and there is no discharge.
Mouth: Check the teeth to make sure they are being worn down and aligned correctly. Keep in mid that "cheek teeth" (molars) can often be the teeth that have issues and is something your veterinarian will need to examine with a scope. If the tongue can move freely, the molars are probably a healthy length, however they can develop sharp points that may cause pain or discomfort to your guinea pig. Also check for any sores or redness. around the mouth and tongue.
Skin/coat: Make sure the skin and coat look healthy. Check for bald patches, scaly skin, or other abnormalities.
Feet: Make sure their feet look healthy and clean and do not have any sores or redness.
Nails: Nails should be trimmed every few weeks. Refer to this link for steps on how to successfully trim nails: https://www.paigespets.org/single-post/2018/07/02/Nail-Trimming-101
Bum: Check your guinea pigs poops to make sure they are normal and not runny. Also be sure there is no blood in the urine. Ensure the area looks clean and dry.
Eating habits: Make sure your guinea pig is eating normally. Eating less (or eating more and losing weight) or another dramatic change can indicate illness and should be treated by a veterinarian immediately. GI stasis (when the gut stops moving) can be deadly and swift care will help give your guinea pig the best chance of recovery.
By carefully monitoring your guinea pig’s health, you can catch signs of illness before they become major problems. Be sure to consult your vet with any concerns.
Disclaimer: I am not a medical professional. Anything expressed in these posts is my own personal opinion and is not to be taken as medical advice.