Alveolar echinococcosis in a dog in the eastern United States

Abstract

An 8-y-old Labrador Retriever was presented to a small animal practice in northern Virginia with a history of recent lethargy. Physical examination findings were unremarkable. Ultrasound revealed several large hepatic masses and multiple smaller masses involving the pancreas. Cytologic findings on fine-needle aspirates of the hepatic masses included inflammation and necrosis with eosinophilic, membranous oval structures consistent with cestode infection. Histopathologic findings for biopsies of these masses included extensive necrosis, inflammation, and PAS-positive hyaline-like membranous material interpreted as metacestode cyst wall. A PCR product was generated from aspirate material using primers specific for Echinococcus multilocularis. Subsequent sequence data were 100% homologous to E. multilocularis NADH dehydrogenase subunit I gene sequences. The dog received daily oral albendazole (10 mg/kg) treatment, but its condition deteriorated, and the dog was euthanized. The dog, born in Mississippi, was brought as a puppy to Virginia with no other travel history. To our knowledge, alveolar echinococcosis has not been reported previously in a dog in the United States; E. multilocularis infection was apparently acquired in the mid-Atlantic region of the United States.

Keywords: Echinococcus multilocularis; United States; alveolar echinococcosis; dogs; polymerase chain reaction.

Figure 1.

Ultrasound image of a cavitated mass in the liver of an 8-y-old dog with alveolar echinococcosis.

Figures 2–5.

Alveolar echinococcosis in a dog. Figure 2. Example of folded membrane-like structures present in sediment of a fine-needle aspirate of a hepatic mass in the infected dog. Modified Wright Giemsa. Bar = 200 µm. Figure 3. Granulomatous hepatitis, fibrosis, mineralization, and acellular hyaline membrane material (arrow) are present. H&E. Bar = 200 µm. Figure 4. Extensive hyaline membrane (arrows) in periodic acid-Schiff–stained hepatic biopsy tissue. Bar = 200 µm. Figure 5. A multilobular mass was adherent to the liver. The serosal surfaces of abdominal organs were diffusely granular with numerous small white foci.