Thank you for your question. Unfortunately, noticeable bleeding is never normal in guinea pigs and is typically not part of their natural cycle. Other causes such as bladder or other urinary stones, infections, or other abnormalities may be causing those signs that you’re seeing. I suggest making an appointment for a full physical exam and husbandry discussion (diet, housing, bedding, etc) as all of these are very important to overall guinea pig health. Please feel free to contact us at any time to schedule an appointment. Thank you!