Blastomycosis is a systemic fungal infection that infects patients primarily through inhalation of Blastomyces der-matitidis spores [65]. The inhaled spores subsequently establish colonies within the respiratory tract [65].
Because the organism spreads through lymphatics as well as the bloodstream, distant sites may be colonized.
B. dermatitidis is endemic to North American soil [65, 66]. Those who reside near the Mississippi, Missouri, and Ohio River valleys are most at risk for contracting disease [65]. Although cats may develop blastomycosis, dogs and humans are more likely to succumb than other species [65, 70, 71].
Young adult, large‐breed dogs, such as Golden Retrievers and Doberman Pinschers, are overrepresented [65, 66, 72, 73]. Some studies demonstrate an apparent predisposition for disease in male dogs [65, 73, 74]. This mirrors what is seen in human medicine [75].
Clinical signs of blastomycosis in dogs vary widely depending upon how well the organism disseminates throughout the patient’s body [65]. Patients with dissem-inated disease often present with a multitude of clinical signs that affect several organ systems [65].
Initially, vague signs may predominate [65]. Affected dogs may present for anorexia and generalized malaise.
Weight loss may persist over an extended period of weeks to months [65].
Pulmonary infection results in tachypnea, dyspnea, and/or cyanosis in 65–85% of canine patients [65]. Thirty to fifty percent of dogs present with concurrent lym-phadenopathy [65]. The same percentage of dogs develop cutaneous signs, including nodules, papules, plaques, and depigmentation lesions of the nasal planum [65] (see Figure 9.13).
Twenty to fifty percent of dogs develop glaucoma sec-ondary to ocular involvement. Others may develop ante-rior uveitis, chorioretinitis, and/or retinal detachment.
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