Hi everyone, I’m Dr Sam, a small animal veterinarian, and today I’d like to talk about a condition that’s quite common in older male guinea pigs, but not often well understood - impaction. If you’ve noticed your guinea pig straining to pass droppings or appearing uncomfortable and smelly around the back end, this blog is for you.

What Is Impaction?

Impaction occurs when a guinea pig is unable to properly expel faeces from their rectum, causing a build-up in the perineal sac. This is a natural pouch located just inside the anus, and in older male guinea pigs especially, it can become stretched and weakened over time. As a result, faeces and soft droppings can accumulate, leading to discomfort, odour, and potential infection. You may notice your guinea pig is still able to expel normal hard faeces despite the softer faeces and cecotropes becoming impacted. 

Who Is Most at Risk?

While impaction can technically occur in any guinea pig, it is most commonly seen in older, unneutered males. As guinea pigs age, the muscles responsible for clearing the perineal sac weaken. Impaction is more commonly seen in entire boars as the weight of their large testicles and surrounding fat pads will over time contribute to the stretching and weakening of the muscles and ligaments used to expel faeces. Boars who are neutered in their younger years do not suffer from the same pathology. 

 Poor diet, obesity, geriatric age and limited mobility can also increase the risk - especially if they are not able to reach their perineal sac and maintain their own hygiene as easily. 

Signs to Watch For

The most obvious sign of impaction is a noticeable swelling or lump near your guinea pig’s bottom. You may also observe straining, dragging of the bottom, reduced appetite, or soft droppings smeared around the hindquarters. Some guinea pigs may become less active or appear grumpy due to discomfort. If you notice a foul smell or discharge, this could indicate infection, which requires immediate veterinary attention.

How to Manage and Treat Impaction

If your guinea pig is showing signs of impaction, I strongly recommend a veterinary examination to rule out other issues such as infection and other underlying issues, as well as to ensure your piggy is receiving the correct treatment. In many cases, mild impaction can be managed at home with regular cleaning of the perineal sac. This involves manual evacuation and gentle removal of the built-up faecal matter. This can be uncomfortable for your guinea pig if caution is not taken, so it is important to use a lubricant such as baby oil to help with the evacuation, along with some cotton tips and gentle pressure. It is normal to have an unpleasant odour, however please consult your veterinarian if the smell is strong or you suspect there may be an infection present. I also recommend to wear gloves during the cleaning process. 

Some guinea pigs may also benefit from weight management, increased exercise, or dietary adjustments. Ensuring your pet lives in a clean, spacious indoor cage for guinea pigs with plenty of opportunity to move around and forage can go a long way in supporting their gut health. Providing soft, absorbent guinea pigs beds also helps prevent faecal matter from sticking and creating further hygiene problems.

Final Thoughts from Dr Sam

Impaction can be quite uncomfortable for your piggy, but it is a manageable condition. Unfortunately once the area stretches it is very difficult to reverse those changes and often becomes a life long condition, however early detection and early intervention is key to prevent the condition from worsening. 

 Like many guinea pig health issues, prevention is often easier than treatment. The most effective way of preventing impaction in guinea pigs is desexing at a younger age, and I encourage you to have this conversation with your cavy savvy vet. Keeping your guinea pigs healthy with a good diet high in fibre, and ability to exercise and move around will also help to keep their digestive health in check. 

If you're ever unsure about your guinea pig’s behaviour or bowel habits, please don’t hesitate to contact your cavy savvy veterinarian. Catching these issues early really does make a world of difference.