In a previous post I discussed the presentation of dogs and cats who have blood in their urine. I mentioned various causes and diagnostic tests available, but I left out the current scenario.
Some years ago, a client called saying "Fuzzy has another one of those bladder infections." (She had previously had two episodes of cystitis, with a bacterial bladder infection.) "She’s passing blood in her urine again." "Is she squatting and straining a lot, like before?" "Well, no… but I’m sure it’s the same thing." "I’m not. I need to see her." On examination I didn’t see anything out of the ordinary, but something just wasn’t right. Patients with bladder infections feel like they have to go, and they feel that way all the time. They do a lot of squatting and straining, and Fuzzy wasn’t. [Don’t get me started on that "Fuzzy-wuzzy wasn’t fuzzy, was he?" song now.]
So, if you have blood in your urine, but no inflammation, what’s the deal? Could be a tumor, could be trauma, could be a bleeding problem. So, I miraculously made the correct choice of which test to run first. We did a complete blood count, which revealed that the cat had no platelets. You need platelets.
Without platelets, you tend to bleed pretty freely. While there are many proteins and complex factors in the blood-clotting process, it’s the little blood cells called platelets that provide the initial plugging of the hole. Without some sort of "scaffolding", the clotting proteins don’t really have a place to lodge and get to work, even if they’re working great. Put some of that blood in a test-tube and it will clot in a normal time period. Make a little cut on the patient, and it will just keep on bleeding.
Curly Sue is a big old dog who just had "a little blood in her urine" last Wednesday. "Probably has a bladder infection", thought her owner. On Thursday her urine was about twenty percent blood, and it was all over the garage. Since she’s an older dog, my initial thought was that she might have one heck of a bleeding tumor in there. Physical examination showed that her gums were a little pale (and you’ve got to be down to half your normal complement of red blood cells for that to happen). She’s pretty furry, so her skin was hard to see. On a hunch, I shaved her tummy, and found little hemorrhages all over. She looked like a dog with Rocky Mountain Spotted Fever, except she only had the spots (no swollen lymph nodes, no fever, and no history of tick exposure, although sometimes folks don’t see the tick). She also had no platelets.
Now when you don’t have platelets, either you’re not making them, or something is destroying them. If they aren’t being made in the bone marrow, then we most likely have a cancerous disease damaging the bone marrow or an auto-immune disease, where the body’s own defenses are destroying the stem cells that make the platelets. This auto-immune reaction, this malfunction of the body’s defenses, can be destroying the platelets later in the game as well. Sometimes this type of reaction occurs secondary to infections or drug administration. Most of the time we really just don’t know why it happens.
So with both Fuzzy and Curly Sue, I got lucky. I can’t say that they got lucky, because having auto-immune thrombocytopenia (a lack of platelets, due to the body destroying them) is not a lucky thing. I feel lucky, because I did the right diagnostic test, they had a treatable disease, and the treatment worked. Both individuals responded to big doses of prednisone to temporarily suppress the body’s defenses and stop the cycle of platelet destruction.
The medical end is a little more complicated than that, but the bottom line is that we have to look at the whole patient, the history, get our diagnostic tests, and do some thinking to get it right. Sometimes your first impression can be wrong. When the data don’t fit your theory, you need a new theory. If you don’t bother to get any data, you wouldn’t know that, would you?