Any time that there is blood, it is natural to worry. That is especially true when there is blood in either of the waste passages. However, the first thing you need to know is what actually causes that blood in the urine. The most obvious thing that you need to check is if they are in season. Of course, only female dogs will have seasons, but it can be a big surprise to the owners when they have their first season. If your female dog has other signs of being in season, then that is likely the cause.
Urinary tract infections are the most common cause for concern when it comes to blood in the urine. Therefore, it is vital that you look out for the other signs of a UTI if you notice blood. If your dog seems to be in pain while peeing, and there is blood, that is a huge sign that they have an infection. Furthermore, check how often they are eating. If they seem to be losing weight, not eating as much as normal, and have less energy, they are other big signs that it is a UTI. As soon as you suspect an infection, make sure you take them to the vet.