You are here:

Guinea Pigs/Guinea pig is ill



We have a 5 year and 8 month old guinea pig. He had a mammary cyst that grew large and started bleeding time to time, but he is always in good health and shape and could walk normally. His cyst doesn't bleed bad, just a bit of blood might come and we apply an anti-biotic ointment and it goes away and it stops bleeding for a good amount of time and it hasn't bled in months.

We start noticing his feces is clumping up and we gave him a probiotic (learned the probiotic has dairy in it) and his feces looked again to be normal. The next day (yesterday) we notice he looks very ill and is laid flat. His eyes are watery and crusty and he doesn't move. We are hand feeding him by mixing water and his pellets and feeding him through a syringe. He is eating the food well, but after a day passed he is still very ill. We are still hand feeding him. Before he became ill, he was eating healthy, moving around and very normal.

We thought he might be sick from germs entering the cyst maybe, so we applied an anti-biotic ointment right now just in case.

I thought this might be a URI, but he doesn't really sneeze or cough.

Do you have any idea what this may be?

Thank you for any information you may give,
God Bless

breast cancer in guinea pig
breast cancer in guine  
I'm very sorry to hear about this Tom. I'm afraid there is not good news in this reply. Most mammary cysts are malignant, i.e. breast cancers. An ordinary benign cyst will heal, malignancies do not.

Although the probiotics did give temporary relief for the stool problem, it is not going to address the cause of all this. Probiotics are not necessarily dairy, they are comprised of good bacteria that is necessary in the gut of all living things to aid in proper digestion. This is why guinea pigs cannot take certain antibiotics. They destroy the normal flora in the gut that breaks down food and the result is a secondary infection caused by the antibiotics. Probiotics are supposed to help prevent this from happening.

I suspect what is happening now is widespread metastasis of the cancer. I'm sorry that I don't have better or more encouraging news. Most probably by the time you get this post he will have passed.

There is nothing you could have done that would have made any difference. Although mammary tumors are not rare in guinea pigs we still have nothing more to offer in the way of treatment. It is in fact a breast cancer and even if you had the vast funds to try chemotherapy or radiation the chances of success are almost nil.  

Attached is a picture of another pig that had a malignant mammary tumor. The small ipod is just there to give a point of reference as to the size of the opening.

The owner went through multiple treatments in the hopes that it was a simple abscess, but when she went to her vet for help he confirmed what I'd said. The poor little thing was gently euthanized to prevent her further suffering.

Again, I wish I had better news for you. My thoughts are with you. It's painful to watch our pets go through these kinds of things.

Guinea Pigs

All Answers

Answers by Expert:

Ask Experts


Pat VanAllen


As is sometimes the case, people in urgent need of information have a higher degree of expectation than those of us as experts are able to give. The experts on this site do their best to give the most accurate and responsible answers possible. We ask that you remember that it is not our intention nor place to criticize the professional advice given by your veterinarian, nor is it appropriate for us to comment on the correctness of a diagnosis made by a licensed physician. Our knowledge is experience based. Although many years of breeding and showing cavies gives me a wealth of experience it cannot change the fact that we as experts are not veterinarians and therefore may occasionally have to reject questions that appear to be asking us to criticize advice given by the licensed professional. Having raised and exhibited cavies for many years I have extensive experience in cavy care and husbandry. I currently have an active breeding program for pedigreed show animals but do not encourage backyard breeding for inexperienced owners. Although I don't encourage breeding for fun I'm always happy to answer any questions from an owner who is in sincere need of help. Pet owners wanting to breed should understand that even experienced breeders have litter losses. The mortality rate is high in cavies. The chance for losing both sow and pups is always present, even with experience. Although this is a site for experts to assist owners, there is no expert in any field who has all the answers. The wisest thing a good expert can know is their limitations. Not having an answer does not diminish one's ability or knowledge. It simply shows that we recognize our limitations and operate within them.


Raised and shown cavies for many years, having aquired my first cavies in the early 1970's as pets. My caviary currently handles 65 + animals in two different breeds and several varieties. Having been in the health care industry as a licensed nurse for 35 years I have hands on experience with care and needs in both humans and cavies. Member of American Rabbit Breeders Association and American Cavy Breeders Association.

Awarded Lifetime Membership in of one of the oldest cavy clubs in the United States, on whose Board I served as Sec/Treas for six years and currently serving as President. Also editor/publisher of the club's quarterly newsletter. We are strong supporters of our youth exhibitors, most of whom are 4H members who are working on cavy projects. Through these projects they become good responsible citizens. We deal with all aspects of showing, breeding, caring for and sharing experiences in the fancy. The cavy fancy is not a new one but in some areas is still relatively unknown. Our goal is to inspire interest in high quality, responsible breeding to improve the species, not just the reproduction of guinea pigs. Our job is to educate owners to help them make the right decisions and choices in the care of their cavies.

Graduate in nursing. Certified in emergency medicine.

©2016 All rights reserved.