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Guinea Pigs/dark oily dandruff on lower back


QUESTION: Hi! I have a 1 1/2 year old boar who has had no health problems up until yesterday. We typically give him some mixed greens and a cherry tomato morning and evening along with Oxbow pellets and timothy hay always being available. He did not eat fresh foods yesterday and today and is not eating his hay. His cage is cleaned daily and there is no poop in it this morning. When we took him out last night to give him some lap time we noticed with the shedding hair on his lower back were pretty good size flakes of dark, oily dandruff(don't know if its coincidental). He did eat a very small amount of apple for me this morning and drank some water. However, when he went over to his hay he nudged it and pulled out a piece or two but then stopped. Any idea what might be going on?

ANSWER: The oily dandruff has nothing to do with his appetite. Boars sometimes get these oily coats and are a mess to clean.  They have a gland at the base of their spine that we call a 'grease gland.' It's unique to boars and can be soooooo messy, especially if they have a light colored coat.

The easiest way to deal with the oily hair is Dawn liquid dish soap. Give him a bath and rub the Dawn in the oily spot. It will get most of it, but not always all of it. You can take a comb and run it through the hair. It will likely pull the hair out around that gland, but it doesn't seem to both the boars. The hair will grow back.

It's almost always an older boar, more than a year old that starts having these issues.  It's really a problem when it's on a white or light colored boar that's about to be shown. It makes a mess of the coat.

As for the lack of appetite, turn him over and check to see if the pouch is filled. The pouch is right between the testicles and at times starts catching soft stool. It builds up and fills that pouch. It's smelly, but needs to be cleaned out.

The best way is to turn him over and put his bum right under some warm running water. That will start to empty that sac that holds the stool. Again, it's always an older boar. It's worse in the warm summer months.

You may have to gently push the sides of the pouch to get the stool expressed out of there, but it needs to be done. It's like a human being constipated, when they can't empty out they lose their appetite.

Give this a try and see if it doesn't correct the problem. If you need to I can send a couple of pictures showing how to clean the pouch.

---------- FOLLOW-UP ----------

QUESTION: Yes I would appreciate the pictures. Not sure how we will accomplish this when he absolutely hates being handled (except for being put on your lap and petting gently or rubbing he side or top of his head. I am taking him to the vets today. He looks even more miserable than yesterday. Thank you for all your help!

Flushing the pouch
Flushing the pouch  
Once you turn him over on his back he will settle down. Just cradle him like you see in the picture. I put my hand on the belly and it gives them a sense of security so they don't feel like they're going to fall. This old boar was willing to let me do anything to him, but I've had many who were not so easy at first, but once they felt the warm water it seem to have a tempering effect.

Sometimes a warm bath does wonders for calming a pig. The water doesn't have to be more than about three inches deep. Some Dawn soap is a great way to clean the hair all over, just be careful not to get it into their eyes and ears. Use a plastic or paper cup to scoop water to rinse with, or I just hold them under the running water. It doesn't have to be too strong a stream. The water has a calming effect.

Did you know that guinea pigs can swim?  Put just enough water in your tub so that they can't quite touch the bottom. Lower him in slowly and let him go. It's a wonderful way to cool them off if the weather is really hot.

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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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