This is a delicate matter, but important. It involves "private parts."

Once your guinea pig boar is an adult he should be checked regularly for accumulated debris on his penis and in the anal sac. With your finger or thumb gently press on the boar's abdomen directly in front of his penis. The penis will extend out of its protective sheath. You may see a sticky white or yellowish coating of hair, bedding, dust, etc. Very, very gently rinse this off with lukewarm water, using your finger to help loosen debris if necessary. When finished, lube the penis and sheath with a little Vaseline or K-Y Jelly before gently sliding the penis back into place. If you see a couple of thin white 'antennas" or prongs protruding from the opening of the penis, leave them alone - they belong there. Any sores on the penis or sheath will need to be treated with Bacitracin or Triple Antibiotic Ointment once or twice daily until healed. Large open ulcers be very painful and may cause your boar to hunch up and cry when urinating. The ointments recommended can be purchased cheaply and without a prescription at a drugstore or health/pharmacy dept. of a department store. If the sores aren’t healing quickly once treatment is started you should seek veterinary advice. A different or stronger ointment may be needed.

Pictures at the sexing page may help show how to protrude the penis so you can check for accumulated debris. However, the best way to learn is to have an expert show you how to check and clean guinea pig boar’s “private parts” for the first time. It's not that difficult to do, but it is hard to explain without visual examples.

Cavy Spirit Sexing page
(see pictures #10, 14, 16)

A guinea pig boar’s testicles and anus are protected by the anal sac, a soft pouch on the rear end of the boar just behind the penis. Bedding, hair and debris can accumulate in the anal sac, sometimes forming a soft clump. This can be cleaned out with cotton swabs and warm water. Gently and carefully insert the cotton tip (rinsed with warm water) into the anal sac and swab out some of the debris. You’re likely to swab out stool at the same time. Continue gently swabbing with a number of cotton swabs until you are bringing out very little debris. Finish by using another clean cotton swab to apply a little Vaseline inside the anal sac. Luckily anal sac cleaning is usually not something that needs to be done often, but should be checked maybe once a month. Some boars may need more regular maintenance than others.

If your boar is getting stool impactions you will feel a hard roundish mass within the anal sac pouch. An anal sac impaction is a clump or ball of stool that the boar is unable to expel himself. Sometimes the clump is made up of many stool “pellets” stuck tightly together. Sometimes the clump is made up of soft, often very stinky, unformed stool. Small clumps can usually be squeezed out easily. The inside of the pouch should then be coated with Vaseline or K-Y Jelly gently applied with a cotton swab. Larger, harder impactions may have to be softened up with warm water and/or baby oil, then worked out a little at a time with a cotton swab. Be very careful not to pull or damage the pouch lining. Impaction can be a recurring problem, so keep an eye on this guinea pig. Daily lubricating with Vaseline or K-Y Jelly will help a boar with a chronic problem get his stool out easier – either on his own or with some assistance.

Boars with chronic stool impaction problems can be more easily lubed with the aid of a 12 cc syringe (no needle) filled with K-Y Jelly or packed with Vaseline. Once stool has been cleared out of the anal sac insert the tip of the syringe into the sack and squirt in a small amount of lubricant. Gently massage the anal sack so the lubricant coats the inside well. This will make stool clumps slide out more easily. Daily or twice daily lubrication may enable your boar to pass more stool on his own, reducing the size or frequency of stool clumps stuck in the anal sac. Disinfect the syringe tip after each use.

If the anal sac is blocking up with soft stool, try adding more fiber or better quality food to the boar's diet. In fact, if you are feeding a guinea pig food that contains nuts, seeds, corn, cereal, or a lot of dried fruit – I definitely recommend you switch to a better quality food. These ingredients can be difficult for a guinea pig to digest and are not nutritionally good for them. These types of guinea pig foods can cause a variety of problems and ailments. Unfortunately the majority of commercial guinea pig diets are not formulated with optimum health in mind and do contain many ingredients that guinea pigs shouldn’t have or may not be able to digest properly.

A good quality guinea pig pellet consists mostly of hay – usually timothy hay or alfalfa hay – not corn, seeds or nuts, cereal balls, or excessive grains. The stuff that looks like trail mix is made for eye appeal to owners, not proper pet nutrition. Feeding a diet that provides balanced nutrition and plenty of fiber can sometimes help with a chronic stool impaction problem. Premium quality guinea pig pellets and good quality grass hay such as timothy, canary, orchard, bluegrass, brome is the diet most recommended by exotics veterinarians. A timothy hay based pellet is usually better for adults than alfalfa based pellets, and may be especially beneficial for boars with impaction problems. For information on premium quality pellets and hay for your guinea pig please visit the web sites below:

KM’s Hayloft
Oxbow Hay Company
American Pet Diner

Fresh foods such as parsley and dark leafy salad greens, carrots and green peppers and other veggies, fruits and berries can also be fed in moderation. Fresh grass and dandelion leaves are terrific guinea pig foods if totally chemical free. For further information on proper diet and fresh foods for guinea pigs please visit the page below:

Guinea Lynx' Diet page

Many cases of chronic anal sac impaction can be significantly improved or even cleared up with a proper diet of:
premium quality pellets (timothy based formula for adult guinea pigs)
unlimited good quality, fresh, green grass hay
moderate fruits/veggies/greens
clean fresh water changed twice daily (do not add multi-vitamins to water)

However, sometimes older guinea pigs develop a chronic problem with stool impaction even with an excellent diet. This may be caused by weakening muscle tone. If this happens you can help your boar live a comfortable and otherwise normal life by clearing him out twice daily and lubricating the anal sac once or twice daily. For further information on anal sac impaction and penis maintenance please visit the page below:

Guinea Lynx' Impaction page

Poopy Pig design at top has been reprinted with Lisa's permission. Visit!

Originally run in Summer 1997 The Guinea Pig Squealer – Issue No. 13 Revised 2/2007
© Copyright 1997 Vicki Palmer Nielsen – Jack Pine Guinea Pig Rescue

This article and the logo are © 1993-2007 Vicki Palmer Nielsen - Jack Pine Guinea Pig Rescue. No copyright is asserted herein regarding the illustrations accompanying the article; copyrights, if any, of the illustrations are retained by the original holders. If you would like to reproduce anything from the website, please first e-mail Vicki for permission at :

Articles & Links   ||   Care Info   ||   Adoptions   ||   Donations   ||   E-Mail