Sudden weight loss - advice/support?

[lydvn]

My guinea pig Comet is 5 years old, has a chronic ear infection, and is on pulse therapy (2 weeks on, 6 weeks off) with Azithromycin. July 2025 (about a year ago), he weighed in at around 1050g. During and right after each pulse therapy, I have noticed in the past year that Comet has lost a bit of weight. He usually gains most or all of it back within the 6 weeks though, so I never really monitored super closely because he always bounces back. I will admit, I should've been weighing him on a kitchen scale, but I stopped doing it randomly and I feel horrible that I did. His last round of medicine was about a month ago, and since losing weight that time around, he has just been losing more and more. The reason I didn't jump on this so soon is because for the past month I haven't been home during the day as often as I usually am, so I wasn't able to monitor any behavior unless it was in the morning or at night right before bed. This weekend, he has rapidly lost weight (is now 618g.. I KNOW, VERY BAD.) and I started giving critical care and extra veggies. He has an appointment with our vet here that is also an exotic specialist on Wednesday (2 days away from writing this) and I am really hoping he pulls through.

More details: He is alert, active, eating and drinking more than his brother which is odd, very happy to hear hay being plopped in the cage and very attentive when he smells veggies in the room. His poop is smaller, but pretty full still, not super dry or anything.

Part of the reason I am so confused and why nothing really raised a red flag is because he has been acting like his usual self.. always happy to see me, happy to eat, playing with his brother, etc. Literally NOTHING has been off besides his appearance as of recent. I didn't notice until it has reached the point where his spine and hips are visible when he is stretched out and eating.

Is there anything else I can do for him until his vet visit? Anything for myself as well? I genuinely have the worst anxiety when it comes to their health, and this is the first time I have made such a big mistake in monitoring... I feel horrible truly. I can barely eat or sleep without worrying about how he is doing now. It's like I am hyper-monitoring now because I am worried I might miss something important. I feel like a horrible owner for letting it go on this long, but I truly did not see any changes in him until more recently. I think it was such a slow change over time that I didn't visibly see any changes until it got to a very extreme point. I don't know how I messed up so badly.

 

[Mrs Tiggy Winkle]

You could start feeding Critical Care, from a bowl if Comet will take it himself, or from a syringe if he won't. Feeding Critical Care replaces hay, not veggies.

For yourself, please try not to beat yourself up and harangue yourself, neither of which actions are helpful! I have been where you are: No regular weighing done, guinea loses weight, I don't notice. Humans make mistakes; we are both human. We can only learn from these mistakes and try to be better next time.

It is important that you look after yourself now, so that you have energy for Comet. So please eat and drink. Focus on what you can do now for both of you.
Keeping my fingers firmly crossed for you and Comet.

 

[Roselina]

I'm sorry you’re in this situation
As @Mrs Tiggy Winkle says focus on what you can do now
We’ve all been just where you are …..it happens

Critical care food is essential , as suggested a bowl of it readily available , porridge oats will help too , a slice of banana
Don’t overdo the veggies ….keep his diet mostly hay as he’s eating ….

Good luck for Wednesday ….could you bring the appt forward ?

 

[lydvn]

You could start feeding Critical Care, from a bowl if Comet will take it himself, or from a syringe if he won't. Feeding Critical Care replaces hay, not veggies.

For yourself, please try not to beat yourself up and harangue yourself, neither of which actions are helpful! I have been where you are: No regular weighing done, guinea loses weight, I don't notice. Humans make mistakes; we are both human. We can only learn from these mistakes and try to be better next time.

It is important that you look after yourself now, so that you have energy for Comet. So please eat and drink. Focus on what you can do now for both of you.
Keeping my fingers firmly crossed for you and Comet.

I have been giving him critical care by syringe (he has never liked critical care), about 10mL each time - sometimes a bit less because he tries to spit it out. I got in around 30mL total yesterday. He is still eating on his own, but just not as much as he usually would of course. I am going to aim for 30mL-45mL today.

Waking up today, he is pooping more frequently, but they are still quite small - still very full and not dry. I am feeling a little more hopeful, trying not to beat myself up too much. He seems to be in a stable condition so my anxiety has calmed down a bit. I just overall hate seeing him looking so sick and small.

Thank you for your kind words, and you're right, we can only learn from these mistakes. I won't be getting lazy with those routine weigh-ins anymore that's for sure.

 

[lydvn]

I'm sorry you’re in this situation
As @Mrs Tiggy Winkle says focus on what you can do now
We’ve all been just where you are …..it happens

Critical care food is essential , as suggested a bowl of it readily available , porridge oats will help too , a slice of banana
Don’t overdo the veggies ….keep his diet mostly hay as he’s eating ….

Good luck for Wednesday ….could you bring the appt forward ?

Thank you for your advice and support, I appreciate it so much. I won't go super heavy on the veggies today, and I will absolutely make sure he is getting that critical care.

I did try to see if they had any sooner appointments, any openings for today, but unfortunately tomorrow is the earliest they have open. Thankfully, they aren't far at all and they are/have exotic specialists. I have been monitoring him so if it does become an emergency, I will be willing to drive him 2 hours to either New York City or Philadelphia for proper treatment.

Overall, he seems happier today which makes me feel a tiny bit better about his overall condition, but I still feel awful for letting him go this long without treatment. I wish I was more aware of his condition sooner.

Again, thank you so much!

 

[Wiebke]

My guinea pig Comet is 5 years old, has a chronic ear infection, and is on pulse therapy (2 weeks on, 6 weeks off) with Azithromycin. July 2025 (about a year ago), he weighed in at around 1050g. During and right after each pulse therapy, I have noticed in the past year that Comet has lost a bit of weight. He usually gains most or all of it back within the 6 weeks though, so I never really monitored super closely because he always bounces back. I will admit, I should've been weighing him on a kitchen scale, but I stopped doing it randomly and I feel horrible that I did. His last round of medicine was about a month ago, and since losing weight that time around, he has just been losing more and more. The reason I didn't jump on this so soon is because for the past month I haven't been home during the day as often as I usually am, so I wasn't able to monitor any behavior unless it was in the morning or at night right before bed. This weekend, he has rapidly lost weight (is now 618g.. I KNOW, VERY BAD.) and I started giving critical care and extra veggies. He has an appointment with our vet here that is also an exotic specialist on Wednesday (2 days away from writing this) and I am really hoping he pulls through.

More details: He is alert, active, eating and drinking more than his brother which is odd, very happy to hear hay being plopped in the cage and very attentive when he smells veggies in the room. His poop is smaller, but pretty full still, not super dry or anything.

Part of the reason I am so confused and why nothing really raised a red flag is because he has been acting like his usual self.. always happy to see me, happy to eat, playing with his brother, etc. Literally NOTHING has been off besides his appearance as of recent. I didn't notice until it has reached the point where his spine and hips are visible when he is stretched out and eating.

Is there anything else I can do for him until his vet visit? Anything for myself as well? I genuinely have the worst anxiety when it comes to their health, and this is the first time I have made such a big mistake in monitoring... I feel horrible truly. I can barely eat or sleep without worrying about how he is doing now. It's like I am hyper-monitoring now because I am worried I might miss something important. I feel like a horrible owner for letting it go on this long, but I truly did not see any changes in him until more recently. I think it was such a slow change over time that I didn't visibly see any changes until it got to a very extreme point. I don't know how I messed up so badly.

Hi and welcome

I am very sorry. These things always happen at the worst possible time. It doesn't make you a bad or neglectful owner. You clearly love your boy.
Piggies are prey animals and very good masking any illness. With their very fast metabolism they can deteriorate very suddenly when that is no longer the case.

Please try to get up to 60 ml (but an absolute minimum of 40 ml) into your boy 0ver the course of 24 hours. Over three quarters of what a piggy eats in a day hay grass fibre and this is what the syringe feed is replacing. It can be likely a pain issue at the bottom of it.
Veg, fresh and dry forage, pellets, treats etc. all together only replace the traditional supplementary role of wild forage.

You may find these guides here helpful:
Weight and Weight Loss Explained: BMI, Weighing, Poos and Feeding Support Levels

All About Syringe Feeding and Medicating Guinea Pigs with Videos and Pictures

Emergency and Crisis Care as well as Bridging Care until a Vet Appointment

You may also check the incisors for potential dental overgrowth of the molars and premolars due to pain:
The edges should be even, clean and self-sharpening against each other.
- If the edge is slanted, then you are most likely dealing with a one sided pain in a root, the jaw or an ear.
- If the edge is jagged, then this points towards uneven chewing.
- If there is a v-shaped indentation, this is usually an indication of restricted jaw movement.
- If the incisors are inward pointing, no longer meeting and potentially discoloured, then you have some major spurs or overgrowth in the back teeth.
This check is not fail-safe but it can help to give you a quick update on the dental situation, seeing that ears and teeth are adjoining and can impact on each other.

As you are US based and dealing with a severe chronic ear infection, it is likely that your boy is suffering from a very widespread strain of respiratory bacteria that is especially prone to move to the middle ear capsule and wall itself in there. It likely comes from a mass supply breeder of one of the largest North America-wide pet store chains where the infection is passed around between stressed young piggies in close confines whose immune system is still under construction - the perfect breeding ground. Because of where that specific bacteria holes up, there can be a wide range of symptoms as the impact affects the body, including the dental system (one sided chewing from pain and dental overgrowth, by eating less hay).
You can find more information of Calcified Bulla Syndroma (its most popular name in the USA) in this link here and perhaps get a foot in from there? CBS Syndrome (Calcified Bulla Syndrome/Walled-in Otitis Media - Symptoms and Care

PS: In comparison, a walled-in middle ear infection with comparable symptoms is rather rare in the UK although calcification of the bulla can increasingly happen in older guinea pigs without an infection. What US cases we have seen on here with a walled-in middle ear infection have been typically middle-aged at 2-4 years.

Unfortunately, all you can do is hang on in there and try to get as much fibrous syringe feed into your boy as possible and hope for the best. The weight is unfortunately very borderline and most of the loss has likely happened very quickly in just a few days while he is still begging and taking food. It can happen to any of us, and you are by no means the first loving owner lured into a sense of false safety by normal behaviour during a busy period.

I hope that this helps you. My thoughts are with you.