Cocciodiodomycosis (Valley Fever)
Suzanne Stack, D.V.M.
southwest (Arizona, N. Mexico, S. California) is the hotbed for
coccidiodomycosis in the U.S. "Cocci" or "Valley Fever" is a fungus
that lives in the desert soil and forms spores when released into
the air. Events such as the
digging of building foundations and pools help this spore release
process along. Periods of rain, which cause fungal growth, are
usually followed by more cases diagnosed. The spores are inhaled by
man, dogs, and horses (cats seem to be resistant), causing the
disease, Valley Fever. Valley Fever is an "equal opportunity"
disease because any dog who breathes air in an endemic region can
get it. There is no vaccine or way to avoid it short of moving away.
Our greyhounds seem particularly
susceptible to cocci, perhaps due to their
normally low white blood cell counts (therefore less
resistance to infectious disease?). Whatever the reason, the
incidence and severity of cocci in greyhounds does seem higher than
in the rest of the local canine population. Immunity plays a part in
which dogs contract Valley Fever. We see as many cases of cocci in
house dogs who are only out for a minute to do their duty as in
outdoor dogs who run around all day with their noses to the ground.
Additionally, just because one dog in a household gets sick is no
reason to expect the other dogs to come down with it. Valley Fever
is not contagious from dog to dog.
Valley Fever is a disease that can be
obscure and may progress before the owner sees sufficient reason to
go to the vet. Some dogs display no specific signs, especially early
on; they just may not feel as well or eat consistently or lose
weight. Despite the name, half of Valley Fever dogs have normal
temperatures at presentation. They may, however, run fluctuating
fevers at home and have times of feeling well interspersed with
times of lethargy.
These ADR ("Ain't Doin' Right") dogs
inevitably go on to develop more specific signs if undiagnosed and
untreated. The most common signs are poor appetite, weight loss,
lameness, bone pain, spinal pain, and coughing. This is because in
the early ("primary") form, the fungus infects the lungs, then moves
on to infect bones ("secondary" form). Lungs and bones account for
most cases; other places cocci can go are the central nervous
system, eyes, and rarely, heart or skin.
With greyhounds, we seldom see the
coughing stage. In most cases, the greyhound presents with bone
involvement or nonspecific illness/weight loss. While other dogs
tend to present with equal proportions of lung vs. bone form,
greyhounds run ballpark 10% lung, 30% ADR, 60% bone, and a neuro
case here and there.
A particular concern with greyhounds is
how much the cocci bone lesions resemble bone cancer (osteosarcoma)
on x-rays. Lesions can be either osteoproliferative (enlarged fuzzy
areas on bone) or osteolytic (holes in bone). If an Arizona
greyhound is ever diagnosed by x-ray with "bone cancer," be sure a
cocci titer is done. I strongly recommend a cocci titer be done
early on any Arizona greyhound sick for any reason. Catching the
disease a few weeks early may save months or years of treatment down
the road. Additionally, be sure
to also check the greyhound for Ehrlichia, as some greyhounds have
both diseases together.
Treatment for Valley Fever has recently
become less expensive as the antifungal drugs used to treat it are
finally off of patent. The most common treatment has always been
ketoconazole (Nizoral) tablets as it is the least expensive
antifungal. However, you can now buy compounded fluconazole, a more
effective drug with less side effects, for almost the same price.
Antifungals tend to cause appetite loss in greyhounds - fluconazole
less so than ketoconazole and itraconazole. If one antifungal isn't
tolerated, sometimes switching to another is the answer. If the dog
isn't too sick, sometimes the dose can be adjusted gradually so that
the dog can slowly work up to the full dose. Force-feeding should be
done if you've got a sick dog who needs the full dose immediately.
If there is one bit of advice I can give
regarding greyhounds and Valley Fever, it is to force feed the
greyhound if he loses his appetite on antifungal meds. You need to
get 3-4 cans of food daily into him, preferably with the most fat
and calories you can find. It is easy to do and can save your
greyhound's life [instructions may be found at
https://home.comcast.net/~greyhndz/tips.htm]. A greyhound
cannot beat Valley Fever if he continues to lose weight during
treatment. Dr. Shubitz at the Valley Fever Center for Excellence at
the University of Arizona told me that most of the problem eaters
she hears of are greyhounds and other sighthounds - she personally
force fed her own Valley Fever whippet for 9 months! Usually after
3-4 weeks of force feeding, a greyhound will be feeling improved
enough from Valley Fever that he regains a reasonable appetite.
The best deals on the antifungals are
with the compounding pharmacies in Phoenix, such as Pet Health
Pharmacy (800) 742-0516. Most dogs will improve on antifungal drugs
if they are not too far gone and are not allowed to continue to lose
weight, but may relapse when the pills are stopped as "azole" drug
action is fungiSTATIC. This means that the drug does not kill the
fungus, but merely keeps it from reproducing, leaving it up to the
body's immune system to get rid of the fungus. Treatment of bone
lesions for years is the norm, and some greyhounds take antifungal
meds on and off for the rest of their lives as relapses occur, or
more prudently, in my opinion, are maintained at a low dose once
apparently "cured" to prevent relapses. Until a few years have gone
by without a relapse, many veterinarians consider Valley Fever not
to be cured, but only in remission.
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