Summary Medical records of 10 dogs in which fungal infection was diagnosed between 1982 and 1990 were reviewed. In each dog, infection was determined to be caused by a single species of fungus, either Aspergillus terreus, Penicillium sp, Paecilomyces sp, Chrysosporium sp, or Pseudallescheria boydii. Nine dogs were German Shepherd Dogs; 1 was a German Shepherd Dog cross, and 9 were females. The most common clinical signs were signs of neck or back pain (9 dogs), weight loss (7 dogs), anorexia (6 dogs), pyrexia (6 dogs), paresis (3 dogs), and paralysis (3 dogs). All 10 dogs had evidence of multiple sites of diskospondylitis. Urine sediment was examined in 6 dogs, and all 6 had fungal hyphae. Urine samples from these dogs produced a medium to heavy pure growth of fungi when placed on Sabaraud's medium. Predisposing causes were not identified in any of the dogs. Four dogs were euthanatized immediately after diagnosis because of paralysis or paresis. The other 6 dogs were treated, and 4 of the 6 received itraconazole. One dog was euthanatized for an unrelated problem after 21 months of treatment; 1 dog was still alive after 4 years of continuous treatment with itraconazole. The other 4 dogs were euthanatized because of eventual paralysis or paresis. Our results suggest that German Shepherd Dogs are predisposed to infection with opportunistic fungi, possibly because of a specific inability to mount an effective response. This predisposition needs to be further studied.