Granulomatous colitis: more than a canine disease? A case of Escherichia coli-associated granulomatous colitis in an adult cat.

CASE SUMMARY: This report describes a 4-year-old cat with chronic intermittent haematochezia and faecal incontinence of 7 months' duration. Investigation revealed severe colonic multifocal mucosal ulcerations and infiltration of the mucosal lamina propria by large numbers of periodic acid-Schiff-positive macrophages. Fluorescence in situ hybridisation analysis of colonic biopsies revealed multifocal clusters of intracellular Escherichia coli. Treatment with fluoroquinolones for 6 weeks led to a complete resolution of clinical signs. RELEVANCE AND NOVEL INFORMATION: The findings reveal that mucosally invasive E coli can also be associated with granulomatous colitis in cats and indicate the need for diagnostic testing of mucosal samples for E coli and other infectious agents.

Evaluation of fluorescence in situ hybridization for the detection of bacteria in feline inflammatory liver disease.

The etiopathogenesis of feline inflammatory liver disease (ILD) is unclear. Therefore, we sought to determine the presence and distribution of bacteria within the livers of cats with ILD using eubacterial fluorescence in situ hybridization (FISH). Histopathology from 39 cats with ILD and 19 with histologically normal livers (C) were classified using World Small Animal Veterinary Association guidelines. Hepatic sections were examined by 16 and 23S ribosomal RNA FISH. Antibodies against cytokeratins and factor VIIIa were used to distinguish bile ducts and vascular structures. Histopathologic findings included non-specific reactive hepatitis (12), neutrophilic cholangitis (NC; 12), lymphocytic cholangitis (seven), cholestasis/obstruction (three), probable lymphoma (three) and acute hepatitis (two). Bacteria were observed in 21/39 ILD and 3/19 C (P = 0.0054). In 8/39 ILD and 2/19 C bacteria were restricted to the outer liver capsule (P = 0.29) and may represent contaminants. The prevalence of intrahepatic bacteria was higher (P = 0.008) in ILD (13/31) than C (1/17). Bacteria in ILD were more frequently (P <0.0001) localized to portal vessels, venous sinusoids and parenchyma (12/13) than bile duct (1/13). Bacterial colonization was highest in Escherichia coli-positive NC cats. Concurrent non-hepatic disease, predominantly pancreatic and intestinal (8/10 cats biopsied), was present in all 13 cats with intrahepatic bacteria. Bacterial culture was positive (predominantly E coli and Enterococcus species) in 11/23 (48%) samples, and concurred with FISH in 15/23 cases. The presence of intrahepatic bacteria in 13/31 (41%) cats with ILD suggests a role in etiopathogenesis. The distribution of bacteria within the liver supports the possibility of colonization via either enteric translocation or hematogenous seeding.

Discrimination between six species of canine microfilariae by a single polymerase chain reaction.

Canine dirofilariasis caused by Dirofilaria immitis is usually diagnosed by specific antigen testing and/or identification of microfilariae. However, D. immitis and at least six other filariae can produce canine microfilaremias with negative heartworm antigen tests. Discriminating these can be of clinical importance. To resolve discordant diagnoses by two diagnostic laboratories in an antigen-negative, microfilaremic dog recently imported into the US from Europe we developed a simple molecular method of identifying different microfilariae, and subsequently validated our method against six different filariae known to infect dogs by amplifying ribosomal DNA spacer sequences by polymerase chain reaction using common and species-specific primers, and sequencing the products to confirm the genotype of the filariae. We identified the filaria in this dog as D. repens. This is the first case of D. repens infection in the United States. Additionally, we examined microfilariae from five additional antigen-negative, microfilaremic dogs and successfully identified the infecting parasite in each case. Our diagnoses differed from the initial morphological diagnosis in three of these cases, demonstrating the inaccuracy of morphological diagnosis. In each case, microfilariae identified morphologically as A. reconditum were identified as D. immitis by molecular methods. Finally, we demonstrated that our PCR method should amplify DNA from at least two additional filariae (Onchocerca and Mansonella), suggesting that this method may be suitable for genotyping all members of the family Onchocercidae.

Cloning and sequencing of equine cardiac troponin I and confirmation of its usefulness as a target analyte for commercial troponin I analyzers.

The analysis of cardiac troponin I (cTnI) in the diagnosis of myocardial injury in domestic animals is gaining popularity. In this study, equine cTnI was sequenced and compared with previously characterized cTnI from other species. A 6-amino-acid N-terminal deletion unique to the horse was identified. This deletion was outside the epitope region of cTnI recognized by most commercial immunoassays and did not affect the ability of a commercial analyzer system to detect recombinant equine cTnI. No function could be ascribed to the deleted portion. These data support the use of commercial analyzers in measuring equine cTnI.

Cloning and sequencing of the canine and feline cardiac troponin I genes.

OBJECTIVE: To determine the gene sequences of canine and feline cardiac troponin I (cTnI), express the protein from the cloned gene in vitro, and validate the use of a commercial cTnI serum analyzer in these species via detection of the expressed protein or comparison of sequence homology. SAMPLE POPULATION: Samples of ventricular myocardium from 5 healthy adult mixed-breed dogs and 5 healthy adult domestic shorthair cats. PROCEDURE: The RNA was extracted from myocardial samples, and cDNA was synthesized via reverse transcriptase polymerase chain reaction and sequenced. The canine cDNA for the coding region was expressed in cell culture and analyzed by western blot and sandwich enzyme-linked immunosorbent assays. RESULTS: Canine and feline cTnI genes were cloned and sequenced. Homology of the nucleotide and amino acid sequences of the canine and feline cTnI genes with human and rodent cTnI genes were high; the greatest homology was detected between canine and feline genes (95% and 96%, respectively). Recombinant canine cTnI protein was detected by a commercial serum cTnI analyzer and by western blot analysis. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that commercial cTnI analyzers can be used to measure serum cTnI concentration from dogs and cats. Additionally, our preliminary characterization of the feline cTnI gene may facilitate further investigation of cTnI and its role in familial hypertrophic cardiomyopathy in cats.