To compare bacterial diversity and community composition among fecal, rectal swab, and colonic mucosal biopsy specimens from dogs and cats with and without chronic enteropathy (CE).
9 healthy dogs, 8 dogs with CE, 8 healthy cats, and 9 cats with CE.
In a cross-sectional study design, fecal, rectal swab, and colonic mucosal biopsy specimens were obtained by colonoscopy from healthy dogs and dogs and cats with CE. Fecal and rectal swab specimens were collected from healthy cats. Genomic DNA was extracted, the 16S rRNA V4 gene region was amplified, and sequencing was performed by use of primers 515F to 806R on a paired-end platform.
For healthy dogs and dogs and cats with CE, bacterial diversity based on the Chao1 estimate of total species richness was higher for colonic mucosal biopsy specimens than for fecal specimens. Analysis of similarities by use of the Bray-Curtis dissimilarity index revealed that the bacterial communities captured in rectal swab specimens were similar to those captured in fecal specimens for healthy dogs and dogs with CE and similar to those captured in colonic mucosal biopsy specimens for both dog groups and cats with CE.
CONCLUSIONS AND CLINICAL RELEVANCE
Rectal swab and colonic biopsy specimens were successfully used to characterize the bacteriome of the intestinal tract in dogs and cats by 16S rRNA gene sequencing. Although the specimen types evaluated in this study were not interchangeable in results, rectal swab specimens were practical to collect from dogs and cats to study bacterial composition within the intestinal tract and may provide an alternative to colonic mucosal biopsy and fecal specimens.
To assess whether hyperinoculation of cats with a feline herpesvirus-1, calicivirus, and panleukopenia virus (FVRCP) vaccine could be used as a model to study interstitial nephritis and to assess humoral and cell-mediated immune responses toward vaccinal α-enolase.
6 healthy young adult purpose-bred research cats.
Baseline renal cortical biopsies, whole blood, serum, and urine were collected prior to administration of a commercial FVRCP parenteral vaccine. Vaccine hyperinoculation was defined as a total of 8 vaccinations given at 2-week intervals over a 14-week period. Blood samples were collected immediately prior to each vaccination, and a second renal biopsy was performed 2 weeks after hyperinoculation (week 16). Renal histopathology, renal α-enolase immunohistochemistry, and assays to detect humoral and cell-mediated immune reactions against Crandell-Rees feline kidney (CRFK) cell lysates and α-enolase were performed. An α-enolase immunoreactivity score for renal tubules and glomeruli based on signal intensity was determined by a blinded pathologist.
Hyperinoculation with the vaccine was not associated with clinicopathologic evidence of renal dysfunction, and interstitial nephritis was not recognized by light microscopy in the time studied. The mean serum absorbance values for antibodies against CRFK antigen and α-enolase were significantly (P < 0.001) higher at weeks 4, 8, and 16 versus week 0. Renal tubular and glomerular α-enolase immunoreactivity scores were higher at week 16 compared to baseline.
Findings suggested that systemic immunological reactions occurred and renal tissues were affected by vaccine hyperinoculation; however, short-term FVRCP vaccine hyperinoculation cannot be used to study interstitial nephritis in cats.