Hello & welcome. I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.
I am very concerned about Barney
Now appetite decline and anorexia is very serious in this species (it is one of the few emergencies for this species). Guinea pigs are designed to be eating all the time, as they have a gastrointestinal tract that is like conveyor belt and needs to be moving/digesting all the time. And if they aren't, then their guts ground to a halt, this can lead to serious consequences. Namely, the bacteria naturally in the system overgrow and release gas (painful!!) and toxins, which cause a pig to get even sicker and less keen to eat or drink. And this could be part of what is depressing him so at the moment.
So, if he is showing this appetite decline already, then to give him the best chance you will want to seek your veterinarian’s assistance now. They can rule out triggering issues (ie dental disease, respiratory infection, GI bugs, obstruction, etc) and most important start treating this appetite decline. Ideal therapy would be combination of hydration (best done with fluids under the skin by your vet), antibiotics, promotility drugs (to restart gut movement), and pain relief. Once these have been administered then you can have your vet show you how to syringe feed him so that you can support him him home.
While your vet can show you how to syringe feed them, you will also find a good outline for hand feeding ill guinea pigs HERE . It is worth speaking to the vet about diets to syringe feed to guinea pigs. I tend to use Oxbow’s Critical Care feed for anorexic guinea pigs. (LINK). This is a highly nutritious herbivore feed that can be easily made into a slurry for syringe feeding. And it is much easier to use then trying to create a balanced critical care diet at home. Though while you are sorting out getting him seen, you can syringe veggie baby food. You can also crush his pellets to add to the baby food or even make a gruel of crushing pellets and rehydration solution (ie pedialyte) to get some nutrition into him. The key is getting food in even if he isn't keen to keep that GI moving.
As well, if you are concerned that he might be becoming dehydrated, you can try and encourage him to drink by offering fresh water. If he is not amenable then you can also try pedialyte or diluted Gatorade (50% diluted with water). These will help replenish electrolytes and get some glucose into his system as well as get fluids in. You can also give pedialyte via dropper of syringe. A typical dose for animals is 4.8mls per 100 grams of body weight per day (obviously divided over all day drinking).
Overall these signs in the guinea pig is a very serious situation and aggressive treatment is necessary to help her overcome this and get them back on track. Therefore, it would be best to have Barney seen urgently by his vet as soon as possible (even as an emergency if he is showing progressive decline). They will be able to check his hydration and initiate treatment as outlined above. They will also be able to examine them to determine and address any underlying trigger that may to be blame for his current state. And the sooner we address the anorexia, get him eating, and address the underlying cause the better chance of getting him through this.
If you do not have a vet for Barney already, then you can find one near you at HERE or HERE . If you are struggling also check here the rabbit database (HERE), as rabbit vets often see our wee pocket pets as well. You can also check RCVS register (LINK). using the advanced search option and clicking on the correct specialty. And just to note if you do want to have him seen now, I wanted to mention that most veterinary practices here do have contingency plans for emergency care for their patients. This means that if you ring the practice, they will likely have a message to direct you on how to contact their emergency service. And if you don't have a vet you can find one local to you, you can check the RCVS Register (HERE) to find your local Vets Now (LINK) who are open all nights/weekends.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,
If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need. Thank you and hope to see you again soon! : )