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You may never have heard of blastomycosis (or if you have, my condolences), but it is caused by a ubiquitous fungus called Blastomyces found in certain parts of the U.S. and it wants to eat your dog and, very rarely, your cat. It lives in soil and sometimes it also wants to eat you (although – important point here – you can’t get it from your dog). You and your dog get it from the same place: dirt. That point is important, so I want to stress it again: Blastomycosis (often abbreviated to just “blasto,” which to me sounds like a really sugary breakfast cereal or the latest aperitif creation from the fine folks who brought us Goldschlager) is not among the diseases we call zoonotic like rabies and ringworm: it doesn’t go from pets to people, or from people to pets.
Since I’m a human and a doctor, but I’m not a human doctor, I can’t talk about the whole wants to eat you part. I can only talk about the wants to eat your dog part, so that’s what I’ll do. (If you have ever had a dog sick with Blasto, I want to point out that I’m not making fun or light of the disease, or any dog that’s ever been sick with it, or died from it.)
Here are the relevant facts about Blasto:
- It is found in the Midwest, usually around the Great Lakes region.
- It usually affects the lungs, eyes, and skin of dogs.
- Symptoms can include anything – weakness, loss of appetite, lethargy, fever.
- Dogs with the lung form usually cough, stop eating, and lose weight.
- Dogs with the eye form have red, painful, and swollen eyes.
- It is very, very, VERY difficult to treat.
- It’s a part of this nutritious breakfast.
Blasto is one of those diseases that can pretty much do what it wants, where it wants and look like anything. It can look like cancer, it can look like a skin infection…anything. It’s an utterly terrifying disease and when I diagnose it, my heart sinks. I know it’s just trying to survive like the rest of us, but Blasto is mean, nasty, and verging on evil.
The only way to prevent this disease is to move to an area that doesn’t have it.
I hear Antarctica is nice.
Many other parts of the U.S. and the world have their own endemic fungal diseases, like histoplasmosis in the Ohio River valley, and coccidioidomycosis in the Southwest. If you move around, you may just be swapping a risk for one disease for another. (One common thread among fungal diseases is that they are as hard to treat as they are to pronounce.)
In order to diagnose Blasto, you have a few options. Let’s say you have a dog with chronic fevers, and your vet decides to do a chest X-ray as part of the workup. With Blasto it looks like someone took a normal dog chest X-ray and put it in a snow globe: little white globby patches everywhere. A dog with cancer that’s spread to the lungs can look quite similar, which is why blasto is often misdiagnosed as metastatic cancer. For dogs with the lung form (they can have it in many places at once, as well. Did I mention this was a nasty disease?) you can sample the airways with an endoscope in hopes of seeing some of the little fungal organisms, or you can do a pretty convenient and relatively inexpensive urine test that is fairly reliable. The turn-around time is several days, which often frustrates people, but it’s a good way to confirm suspicions of blasto. It’s not 100%, but it’s good: no test is right 100% of the time, a fact pet owners should remember.
For the eye form, many veterinary ophthalmologists are well versed in dealing with it, so if you have a dog with an eye problem that hasn’t resolved after seeing your family veterinarian, ask them about a referral to an eye specialist. Sadly many dogs with the eye form will end up losing the eye due to the damage caused by the fungus.
The skin form is the easiest to diagnose. Dogs with the skin form often have chronic open sores that ooze green goo (which is dead fungus, bacteria and white blood cells: pus), and it doesn’t respond well to antibiotics (more on that below). To diagnose the disease, you can often take some of that green goo, put it on a slide, send it to a pathologist and get your answer in three to five days.
The reason I say doesn’t respond well to antibiotics instead of doesn’t respond at all is that the sores from blasto can become infected with bacteria; remember that blasto is a fungus, a whole different type of organism than bacteria and viruses. If the sores become infected, it’s like a ship full of pirates (blasto) that’s stopped to take on a load of dangerous lunatics (bacteria). You have just added badness to the badness. If you get rid of all the lunatics with antibiotics, you still have a ship full of pirates. That’s what antibiotics do to the skin lesions in blasto, and why they may have a small response to antibiotics.
So what does it respond to? Well, if you’re lucky, it’ll respond to antifungal drugs like itraconazole, ketoconazole, or fluconazole. But like much with this disease, it’s not that easy. First, antifungals can cost a lot; depending on the size of the patient, the drug alone can run into the thousands. It doesn’t clear up quickly, either. Dogs who are being treated can take the medication for months on end. And sometimes the medication themselves can have nasty side effects (all medications have the potential for side effects, but antifungals are more likely to make patients feel sick than most drugs we use). However, unlike coccidioidomycosis, the patient doesn’t need to be on an anti-fungal for life after recovery.
One of the most heartbreaking aspects of this disease is that in many cases the treatment can lead to the patient’s death. If the dog has lungs full of fungus, the dead organisms can set off such a strong reaction by the immune system when treatment starts that the inflammation alone can make the lungs worse and kill the patient, or make them so desperate for air that their owners choose to euthanize. It’s like the ship full of pirates setting fire to the ship as it sinks below the water. Treating a dog with the lung form of blasto has about a 50% success rate.
So here’s a summary of my thoughts about blasto:
- It’s hard to diagnose.
- It’s impossible to prevent.
- You have to treat it with a drug that costs thousands.
- And can make the patients even sicker.
It’s an evil disease. I don’t care if it is just trying to survive. Owners and veterinarians alike often experience an emotion sometimes referred to as helplessness, but unfortunately that's the reality.
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