Weight gain continuing long after adoption

[AviN4]

We adopted 3 female guinea pigs, Frankie, Carli, and Stevie in July 2025, approx. 13 months ago. The records we have from the shelter indicate that, at adoption, they were approx. 1 year old. We have been weighing them approx. weekly since adoption. They have each gained a substantial amount of weight over that period:

• Frankie: 1050g to 1366g (30% increase)
• Carli: 976g to 1364g (40% increase)
• Stevie: 833g to 1162g (39% increase)

Stevie seems to have mostly reached a plateau long ago, but Frankie and Carli have continued to reach new record highs every few months. I'm attaching a chart below. Note that to make weight changes more apparent, I've set the Y axis to start at 700 grams. Apologies for the chart crime.



And in case it helps assess their weight, here's a recent photo. Frankie is on the left and Carli is in the back.



I went through the Guinea Lynx instructions on checking whether they are too chubby:

The easiest way to tell the status of your pigs' fat stores is to regularly run your hands down the entire length of the body, starting right behind the ears. In a well proportioned pig, you will be able to feel both the ribs and the backbone going "bump-bump-bump" under your fingers. These bumps should not be sharp or obvious, but palpable. If you are unable to feel those bumps - the fat stores are too thick and your pig is too chubby. If the bumps are very noticeable, then your pig may be too skinny.

I'd say that I can feel the backbone and many of the ribs if I try. So that seems consistent with their weights being healthy at this time. However, this assessment feels very subjective to me, and I'm not sure if I'm getting it right. In addition, even if their weight is fine now, I want to ensure they are on a healthy trend moving forward.

I understand from reading other threads that weight gain after adoption is common. But I'm unsure if it should be continuing more than a year later, even if gradually.

This is what their diet looks like each day:

• Unlimited oat hay, mostly because I have grass allergies. However, we are experimenting with transitioning them to orchard grass hay.
• Unlimited water, of course.
• 1/2 cup of Oxbow timothy pellets, between the 3 of them.
• A lot of veggies. This is where we spoil them. I'm not sure how much, but it could be 24 oz per day in total, between the 3 of them. However, almost all of these are low calorie healthy veggies: green leaf lettuce, a choy lettuce, cucumbers, and bell peppers.
• Occasional Oxbow Simple Rewards treats. Perhaps one treat per guinea pig per day, if even that.

They are often active, spending much of their day walking and running around their large C&C cage. They have a loft and often use it. I estimate that their floor space is about 14 sq ft with the loft.

They have shown no evidence whatsoever of mobility problems. Their ability to run and jump remains impressive to me.

We don't give them much floor time. Only about an hour per week, during cage cleanings. Floor time has challenges for us, and they seem to be happy enough running around inside their cage.

I am still only mildly concerned at this point, but it's been a mild concern for a while now, so I thought I'd request feedback here.

[Lynx]

You have already read the weight guidelines I was going to suggest! If you'd like them to get more exercise, it is likely enlarging the cage - maybe adding a level? -might help. I suspect the oat hay has more sugars in it and might contribute to their weight gain (you will know more after you transition to the orchard grass you hope will work out).

My dsl line was cut and I am temporarily using a weak and frequently disconnecting wireless service thanks to a neighbor. The dsl technician did not show up today :-( Not fun sitting on the patio with the mosquitos!

Your new guinea pig family is so cute!

[AviN4]

Thanks Lynx. I'm sorry to hear about your Internet problems and the mosquitos. I appreciate you taking the time to respond anyways. We already have a 2 x 1 loft expansion, and I don't think it would be practical to expand it without also increasing the floor space. Maybe expanding the floor space is an option, but we are in the NYC area and our floor space is tight. I also find that more floor space increases bedding requirements and cleaning effort. For reference, our current cage, with the loft upgrade, corresponds to this one.

I think for now we'll attempt to continue the transition from oat hay to orchard grass hay and see how it goes. I have more tools in place to mitigate my grass allergies than I did in 2018: larger apartment, air filters, face masks, gloves, and a robot vacuum. So maybe it'll be fine for me this time around. We'll continue to weight weekly as well.

[Lynx]

Yes, lots of tools!

DSL/phone line technician showed up today. He says about a mile away the fiber company laying cable cut the line in one place and damaged it in another. It may be late next week or even later before I get service. His suggestion was tmobile or starlink :-( What I have is very slow but it was adequate for me.

Using a weak connection from a neighbor right now on my laptop.
One bar :-( Yesterday, nothing.

I intend to get fiber (the cheap service is only $50) but it will be weeks before I can get a fiber connection. The road I live on has not yet buried it and installed connecting posts (a road 500' away has it).

[charliehampton]

It sounds like you’re keeping a really close eye on their weight and overall condition. The chart is helpful, especially since Frankie and Carli are still gaining while Stevie seems to have leveled off. Their diet also sounds well monitored, with plenty of hay, vegetables, and controlled pellets. Since you can feel their backbone and ribs and they’re still active, it sounds like you’re being thoughtful about their health rather than simply focusing on the numbers. The gradual transition to orchard grass seems like a reasonable thing to try while keeping an eye on how their weight changes. They also look very happy and comfortable in the photo!