Guinea Pig Home

How to Weight Log

You’ll need a good scale. We’ve found that an electronic 2.2 kg capacity postal scale is an excellent choice. They can be purchased for as little as $30. As these scales have a top surface smaller than most full-grown pigs, we place a large plastic plate on the scale. When you power on the scale with the plate in place, it will come up at zero (alternatively, most scales have a “tare” function that will zero them after they are on). We use grams, and record to the one gram level, but pounds and ounces are fine, as long as you are recording to the 0.1 ounce level.

You should try to weigh your animals at approximately the same time on the same day every week. It is only necessary to weigh more often when you are tracking a health problem. Record you weights in a spreadsheet—we use Excel, but any spreadsheet can handle this simple task. Put the date in the first column, and dedicate a column to each of your animals.

Monitoring

For the first two months, you’ll be developing a baseline. Your data will have limited value, and you should contact your veterinarian if you have concerns about the variations you see. Let’s look at our first example, the variations we typically see in an adult healthy animal.

As you can see, this animal’s weight averaged about 1025 grams, with a high of 1085 and a low of 980—or about ±5%. I’ve found this to be typical for our animals on a steady diet; you may get a somewhat different result.  Note that this level of variation can happen over brief time intervals, even as short as a week. So once you get a good baseline of two months data, you will have a feeling for the typical variation, allowing you to not worry over meaningless changes.

Our second example is of an animal that often has a skin problem in summertime, which causes her to itch one or more places on her back until raw. You’ll notice her weight was averaging right around 1400 grams (a big girl!) until mid-summer, when a 200 gram drop happened in 3 weeks. That is a 14% drop in a short interval.

After treatment by our vet relieved her itching, it took several months to regain her original weight. The shape of this curve is very typical of a generic illness—a sharp decline followed by a slow rise after treatment.

You may see a weight loss associated with surgery, such as spaying and neutering. Consult your vet on what weight loss to expect. Some guinea pigs may have a gradual weight loss when on certain medications, such as antibiotics.

Our last example is the last year of a guinea pig’s life. Note the gradual weight loss beginning approximately 6 months prior to death. We’ve observed this slow decline in several animals. This particular animal had minor surgery in October 2001, which resulted in brief 10% weight loss. About a month after this, he was diagnosed with cancer. The steroids he was given resulted in increased appetite, and he held his weight until just 2 weeks prior to death.

Using Weight Logging

The primary use for weight logging is for health monitoring. Guinea pigs are very adept at hiding their illnesses, but they can’t hide a weight loss. Take your animal to the vet if you observe any significant weight loss—either short-term or long-term. When you go to the vet, bring your weight log with you.

For older animals, you can note a slow decline in weight and increase the caloric content of their food.  Consult your vet about what foods to give you senior pigs to keep them in good shape.

You can also use logging to monitor the weight of an obese pig, as you follow your vet’s instructions to get them to a healthy level.

Steve Conard is a director of and fosterer for MGPR. He has had guinea pigs as the family pet since 1970.