Here's why:
* Social Hierarchy: Guinea pigs have a social hierarchy, and dominant females may assert their dominance by spraying urine, but typically they do this on objects or their territory, not directly on other guinea pigs.
* Stress: If there's conflict or stress between two female guinea pigs, urination may be a sign of fear or anxiety. But even then, it's more likely they'll urinate in their cage or on the floor.
* Medical Conditions: If one guinea pig is urinating on another frequently, it could be a sign of a medical condition, such as a urinary tract infection.
What to look for:
* Frequency: Is it a one-time occurrence, or does it happen regularly?
* Context: Are the guinea pigs fighting, or are they relaxed?
* Other symptoms: Are there any other signs of illness, such as changes in appetite, lethargy, or difficulty urinating?
What to do:
* Observe: Watch your guinea pigs closely and note their behavior.
* Consult a vet: If you're concerned about your guinea pigs' health, or if urination is happening frequently, it's important to consult a veterinarian.
Remember, guinea pigs are social creatures, and proper care and handling can help prevent stress and aggression, leading to a happier and healthier life for your pets.