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Canine Blastomycosis is a systemic fungal infection caused by Blastomyces dermatitidis. This parasitic fungus
grows as a mold in moist soil or decaying vegetation and can release spores into the environment that can be inhaled
by animals or humans. Young dogs that have access to the outdoors are prime candidates for blastomycosis infection
however, infection has also been documented in cats, horses and ferrets. Normally, blastomycosis infection will begin
in the lungs after spores are inhaled and transform into large thick-walled budding yeast, which can multiply and
disseminate to other areas of the body. Potentially, local external infection (cutaneous blastomycosis) can occur
displaying characteristic lesions on the nose and paws. However, these symptoms are often indicative of disseminated
disease rather then external infection. Once a dog is infected by B. dermatitidis several clinical symptoms
may arise including anorexia, weight loss, depression, coughing, ocular disease and skin lesions. Respiratory distress
is also fairly common particularly in advanced cases of the disease. Unfortunately, all breeds are susceptible to
blastomycosis infection and symptoms may progress rapidly, often leading to death if it is not diagnosed early and
treatment is not provided.
Previously, the only means of conclusively diagnosing blastomycosis were cytological and histopathological examination.
These methods often require a biopsy and can be time consuming, allowing for continued proliferation and spread of the
infection. HealthGene Laboratory has recently introduced a PCR based assay that allows for timely and highly efficient
detection of B. dermatitidis. The implications of this technology are significant because early detection and
treatment of blastomycosis greatly improves the chances of survival for the animal. In the early stages of treatment
large numbers of fungi begin to die in the lungs and often elicit an inflammatory response. Therefore respiratory
distress is often a significant problem in the first few days following therapy. Since the severity of the infection
will determine the amount of fungi inhabiting the dog’s lungs, early diagnosis and treatment is an efficient means of
reducing post-treatment respiratory distress and can significantly influence a dog’s survival rate. Additionally,
because PCR testing is DNA based, any form of B. dermatitidis can be detected whether the infection is in its
advanced stages, or present as a protective spore in it’s preliminary form. Test requirements include 2 ml of whole
blood in a lavender top tube (EDTA) and a swab of the infected area or lesion.
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