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Guinea Pigs/guinea pig poo change


Hello there. I have 2 female guinea pigs, both about a year and a half old. Over the past few days, I have noticed a big change in their pool. Its usually plentiful, harder, and brown in color. It is now, very mushy, very dark in color, almost looking black, and not nearly as plentiful as usual. It happening to both my girls. I had been feeding them Mazuri Timothy based guinea pig diet (pellets). I recently switched to Oxbow adult guinea pig diet. I also feed them veggies, but have always done that. Do you think itcould be the pellet change? They also get unlimited hay and water, of coarse. Thank you.

It could be the diet change.  You don't mention what veggies you're feeding, but you might want to stop that for a few days and see if the color and consistency returns. Dark stools can mean a variety of things but is usually the result of diet.

Go back to your original Mazuri pellets. They are a top rated pellet for guinea pigs and there really shouldn't be any reason to change unless it is one of cost, which I understand. After a couple of days without the veggies, and back on the Mazuri feed, you can see if the stool is going to return to normal. That shouldn't take more than 48 hours.

Start the veggies, one at a time. That way if the dark stools return you will know which veggies they are reacting to. In other words it's a matter of testing them to rule out each thing one at a time.

Although they may not be particularly happy about losing their veggies for a few days, they will indeed get over it.  

Please let me know how this works for you, and if you have any other questions please feel free to ask.

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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.

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