What Is Blastomycosis In Dogs?
Questions and answers about Blastomycosis
Blastomycosis, sometimes referred to as "Blasto", is an
elusive fungal organism that as part of its life cycle has
the interesting nature to exist as a single-celled yeast
organism. The organism grows in certain types of soil as a
fungus (or lays dormant as a spore waiting for better
conditions). If soil, humidity, and temperatures are just
right the spores grow as a fungus and generates tens of thousands of
very tiny spores. If inhaled by a person or animal from disturbed
soil the spores evolve into replicating yeast organisms in the
tissues! Blastomyces dermatitidis can infect humans,
dogs, occasionally cats and some other warm blooded
My dog has
Blastomycosis. The veterinarian
took some x-rays and looked at something under the microscope and
apparently this disease could be very serious.
Do dogs recover from Blasto and will he ever be normal
again. He's lost weight, has a poor appetite and coughs when he
gets excited; plus the vet found an infection at one of his toes near
Blastomycosis can be very serious especially when these
yeast-phase organisms are present in the lungs or other organs.
Whether or not your dog recovers, and many do with proper therapy,
depends on many factors such as immune system vigor, diet, body
size, and response of the organisms to medication. If these
tiny yeast-phase organisms invade bone tissue or other areas where
blood supply is limited such as the cerebrospinal fluid or skin, it
may take months of anti-fungal medications to effect a total cure.
Ocular blastomycosis can cause rapid and permanent blindness.
Many dogs seem to get worse for 5 to 8 days after
treatment starts, probably because their already overtaxed
biochemistry now has to get rid of tens of thousands of dead yeast
organisms. Be sure to stay in close contact with your
veterinarian throughout the treatment time and be aware that a
flareup of the original infection can occur if the organisms weren't
entirely eradicated or possibly from a second exposure to the fungal
| Doctor's Notes
Blastomycosis is called a diphasic pathogen because it exists
in two forms. The infective organisms are extremely tiny
particles called spores that grow from the fungal phage of the
organism. Growing on decaying, moist, organic
material, usually close to a bog, stream, lake or river, the
fungal form generates thousands of tiny spores.
If these little "seeds" called spores enter the body, usually via inhalation,
they can germinate into single celled yeast organisms. The
yeast then propagate via budding... they grow a second self from the
Morphing from a fungus to a yeast, this biphasic organism can
get lucky on occasion and infect humans, dogs, cats and other
Some patients, no
matter how intensive the therapy, may not
survive systemic infection with blastomycosis.
It can be mistaken for metastatic cancer on
x-ray views, mistaken for tick borne disease if
arthritic discomfort and fever are present,
mistaken for "kennel cough" or pneumonia.
Identification of yeast organisms is the
best assurance of an accurate diagnosis.
An accurate urine test is now available, too.
that people can get blastomycosis from their dog. Is this true?
Under certain conditions, yes. The person would
need to get the live blastomycosis cells from the dog's lesion into
a cut or opening in the skin or somehow get infected material into
the nasal cavity or eye tissues or otherwise inoculate themselves
with infected material from the dog. It may be possible that a
sneeze from an infected dog could transmit infected respiratory
material directly into the eyes or an open wound of the person.
Human disease might then occur especially if the person is immune
compromised or is on immune suppressing medications.
Where a dog and a human in the same household
each develop blastomycosis the disease was most likely picked up
independently from the same source outside. People love to
garden... dogs love to dig in gardens, people spread topsoil... dogs
love to sniff around and dig up topsoil; people dig post holes, rake
up waterside debris, explore beaver lodges. Our dogs
often accompany us on these activities and work their sniffers at
ground level rooting around organic-smelling soils. So when a
person and their dog develop blastomycosis usually one does not
contaminate the other but rather, the dog and human pick up
infective spores from a common source in the environment.
Humans seldom contract blastomycosis from a dog or cat... but under
unique conditions it could happen.
Get a diagnosis!
If your dog or cat is sick your veterinarian will need
specific data to establishing a correct diagnosis.
that data all your veterinarian can do is make a judgment call such as
"it could be..." or "it probably is ..." so for you to
get a correct diagnosis your veterinarian will need your permission to do
organisms are not usually found in the water but rather in the organic,
moist soil along shorelines.
I just found out my dog
has blastomycosis! My veterinarian says we live
in an endemic area for this disease and she looked for the organisms under
the microscope and showed me what they look like.
The veterinarian says since we got the dog
examined before the
infection has advanced too far we stand a good chance of curing it but
there never can be 100% assurance that he will recover.
What is blasto, anyways? How come my dog
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what is... treatment... diagnosis
You and your dog are lucky that the doctor is
familiar with blastomycosis. Endemic means above average numbers of
the disease occur in your local area. Blasto is a
single celled organism during the infection and a fungal organism in the
environment. Your dog probably got
blasto by inhaling very tiny spores from dried soil that contained
the fungal stage of the organism.
In dogs the disease is considered very dangerous
and often will be fatal if a diagnosis and treatment is delayed or if the patient is not
treated with specific anti-fungal medication. Commonly used
antibiotics for bacterial infections will not work against the infective yeast
phase of blastomycosis.
A positive diagnosis is made by seeing the organisms through the
microscope in a sample of tissue or fluid. Sending a serum sample
to a lab for a blasto titer may be misleading. And tissue specimens for a culture
of the fungus may take weeks to acquire. There is a highly
reliable urine test available, too.
Treatment: Some very sick dogs require hospitalization, fluid
therapy, and intravenous anti-fungal medications. Critical care in
the hospital for over a week may be needed. Oral medications
such as ketoconazole, itraconazole and fluconazole are often used in
addition to antibiotics to assist in controlling bacterial opportunists.
1.) Avoidance of close contact with disturbed soil near
2.) Awareness of the usual signs especially if you live in a
geographic area where blastomycosis cases have been reported.
3.) Early examination and proactive pursuit of a diagnosis if your
dog is sick.
4.) Try to inhibiting your dog from digging in the ground.
Boggy shorelines, beaver dams and
lodges, river and lake edges with organic ,decomposing soil are typical
areas where blastomycotic fungi will grow. Spores from these
fungal growths can be inhaled and eventually infect nearly any tissue in
Dogs that have recovered from a blasto infection can become infected
again. However, we are not certain that the second infection is
truly due to a new exposure!
It is possible that even after treatment
has stopped and a recovery is presumed, some blasto organisms can remain in the dog's body.
Over time they can reproduce and cause illness.
Most dogs that begin a second set of treatment
respond very well and often can recover completely.
dog was just euthanized because of blastomycosis; it got into his
lungs and spread into his eyes and skin. We thought he had cancer at
first but finally the diagnosis of blasto was made and he was doing so
poorly, and was blind, we elected to end his suffering.
there any way to prevent blastomycosis or is there a vaccine against
it? I don't want my other dog to ever get it.
There is no vaccine against blastomycosis, partly because
being a yeast organism when infective (and a fungus organism in the
environment) it is very difficult to create a vaccine against
it. In your dog's case if you know where he likely was
exposed, such as a stream side, topsoil for gardening, digging up a beaver
lodge or dam... anywhere there may be richly organic, moist soil could
harbor pockets of Blastomyces organisms.
Dogs that like to dig holes hunting for gophers
or chipmunks and dogs that dig themselves a dirt bed to lay in may have
greater exposure to inhaling blasto spores associated with the soil.
Blastomycosis does not grow "in the water" of a pond, lake or
stream but may grow in the shoreline soil and has been found in the dried
mud of beaver lodges and dams. Below are a few points to remember
Do not allow your dog to dig holes
Have an exam done if any cough, skin sore, or weight loss is noted
Swimming is OK but try to avoid boggy or muddy shorelines
Fever of 104 to 105 are common during a blastomycosis infection
Often called Blasto,
this disease enters the dog through the
respiratory tract when microscopic spores from
the fungal phase are inhaled.
then develop into budding yeast organisms and
can be carried throughout the body through the
blood and lymphatic circulation.
confined only to the lungs the infection is more
likely to be cured than if the organisms
have spread to other areas of the body.
is the usual treatment for blastomycosis and is it always successful in
curing the disease?
There are several anti-fungal medications that can
be very helpful in eliminating the organisms causing blastomycosis.
Ketoconazole, itraconazole and fluconazole oral medications are
often used and are continued for at least a month after all signs of
disease have subsided.
Many patients are so sick they need hospitalization and
supportive care. Therapy for blastomycosis may include i.v
fluids, forced feeding, wound management for open and draining
lesions, and antibiotics to control secondary bacterial infection.
Protective gloves should be used during patient management of open
sores because there is potential for human contagion if yeast
organisms enter the caretaker's skin through an open
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