Rhodococcus equi Infections in Dogs.

Five cases of Rhodococcus equi infection in dogs were identified from 2003 to 2014. Three of the dogs had severe, internal lesions attributable to R. equi that have not been previously described: endophthalmitis, endocarditis, and suppurative pleuropneumonia. Isolates from 4 of the dogs were analyzed by polymerase chain reaction for Rhodococcus virulence-associated plasmid (vap) genes. One isolate was vapA-positive, 2 lacked a virulence plasmid, and 1 carried the novel vapN-associated plasmid (pVAPN) recently characterized in bovine isolates. The pVAPN plasmid has not been described in isolates cultured from companion animals. Four of the dogs either were receiving immunosuppressive drugs or had endocrinopathies. R. equi has the potential to cause significant infections in dogs, and immunocompromised animals should be considered at risk for infection.

Achlya sp. Dermatitis in an American Alligator (Alligator mississippiensis).

Oomycetes are water moulds in the kingdom Protista and are not considered true fungi due to the structural lack of chitin and ergosterol. Many oomycetes are pathogenic, such as Pythium spp., and many fish are prone to Saprolegnia spp. infections, particularly in stressful farming situations. A juvenile American alligator (Alligator mississippiensis) was presented for necropsy examination with white, gelatinous, raised lesions over ulcerated regions of skin on the limbs and tail. The alligator came from a hatchery with age-divided enclosures, and several of the animals within the same enclosure showed similar lesions. Numerous hyphae with non-parallel walls and sparse, non-dichotomous branching were observed histologically on Gomori's methenamine silver staining within the ulcers. Although no organisms were detectable via polymerase chain reaction testing of fresh or formalin-fixed tissues, the organism was cultured and sequenced as an Achlya sp., an infrequently identified oomycete. To the author's knowledge, this is the first description of an oomycete infection within the class Reptilia.

Meningoencephalitis in a dog due to Trichosporon montevideense.

Meningoencephalitis due to infection with Trichosporon montevideense was diagnosed in a 4-year-old dog with a brief clinical history of rapidly progressing neurological signs that culminated in a comatose state. No significant gross lesions were found at post-mortem examination. Microscopically, a few scattered areas of pyogranulomatous inflammation with a few small, non-pigmented fungal hyphae were found within the cerebrum surrounding the lateral ventricles. A Trichosporon sp. was identified through culture of the brain and species was determined via sequence analysis of the internal transcribed spacer region of the Trichosporon rRNA gene. DNA in-situ hybridization confirmed the diagnosis. This is the first reported case of Trichosporon-associated meningoencephalitis in a dog.