Successful management of histiocytic ulcerative colitis with enrofloxacin in two Boxer dogs

Successful treatment of three dogs with fluoroquinolone-resistant Escherichia coli associated granulomatous colitis

Successful resolution of Escherichia coli associated granulomatous colitis (ECGC) is becoming a challenge due to the development of fluoroquinolone resistant Escherichia coli, which is associated with poor prognosis. Three dogs presented with signs of chronic colitis and were diagnosed with ECGC. All three were initially treated with enrofloxacin and trimethoprim-sulfamethoxazole, without clinical improvement. Despite the fact that culture and susceptibility testing results demonstrate resistance to fluoroquinolone and trimethoprim-sulfamethoxazole, the addition of amikacin fully resolved the clinical signs in all three cases. This case series describes the clinical presentation, diagnostic findings, and successful treatment of three dogs with fluoroquinolone-resistant ECGC. It suggests an alternative strategy for multidrug-resistance ECGC patients. Further investigations are required to confirm the efficacy of and to determine the molecular mechanisms underpinning the apparent success of aminoglycoside antibiotic combinations for treatment of ECGC.

Correlation of cytology to histology in a case of canine granulomatous colitis in a Boxer dog

A 2-year-old castrated male mixed breed dog presented to the North Carolina State Veterinary Teaching Hospital for chronic diarrhea with hematochezia and weight loss. Cytology performed on a rectal scraping revealed macrophages containing magenta, light pink, and variably blue granular inclusions, and phagocytosed material concerning for infectious organisms. Histopathology was consistent with granulomatous colitis and identified intra-histiocytic bacterial organisms, confirmed by fluorescent in situ hybridization (FISH)-tissue culture-confirmed Escherichia coli. Based on these findings, a diagnosis of granulomatous colitis was made. The patient was successfully treated with oral enrofloxacin, and near-complete remission of signs was achieved within 6 weeks. This report describes a case of granulomatous colitis in a mixed breed dog, and is the first published description of the cytologic features of this uncommon disease, offering a valuable cytologic-histologic correlation. In this case, the cytology was helpful in identifying features consistent with granulomatous colitis and prioritizing the differential diagnoses and diagnostic plan.

[Granulomatous colitis in a French Bulldog puppy]

A 6-month-old French bulldog was presented due to chronic large intestinal diarrhea of 4 months duration. The diagnostic procedures initiated by the referring veterinarian had resulted in a tentative diagnosis of chronic enteropathy, however treatment consisting of elimination diet as well as antibiotic, anthelmintic, anti-inflammatory and immunosuppressive medication had been unsuccessful. By means of endoscopy and histological examination, pronounced erosions and ulcerations of the colonic mucosa were detected. Fluorescence in situ hybridization enabled the identification of invasive Escherichia coli within the colonic mucosa and colonic macrophages, allowing for the diagnosis of granulomatous colitis. The dog showed complete remission of clinical signs following 8 weeks of treatment with enrofloxacin. This case report describes the first successful treatment of granulomatous colitis with enrofloxacin in a French bulldog puppy in Germany and is intended to sensitize the reader to this disease in (young) dogs.

Clinical characteristics and long-term outcome of E. coli-associated granulomatous ileocolitis in dogs: five cases (2010-2014)

OBJECTIVES

To describe the clinical characteristics and long-term outcome of Escherichia coli-associated granulomatous ileocolitis in dogs.

METHODS

Retrospective review of medical records from dogs with periodic acid-Schiff positive (PAS+) granulomatous ileocolitis and mucosally invasive E. coli in the ileum and colon. Initial bacterial colonisation was evaluated using fluorescence in situ hybridization (FISH) in all dogs and corroborated with colonic and/or ileal culture, when performed.

RESULTS

Four boxer dogs and 1 French Bulldog with PAS+ granulomatous ileocolitis (GIC) were evaluated. All dogs had chronic diarrhoea refractory to empirical therapy. Ileocolonoscopy revealed mucosal haemorrhage and ulceration in the ileum (3/4) and colon (5/5). E. coli were visualised as clusters within the ileal and colonic mucosa. Complete (CR, 4/5) or partial (PR, 1/5) clinical response to fluoroquinolones was noted in all dogs within 30 days. CR was sustained in three of four dogs (median disease-free interval 40 months, range 16 to 60). Two dogs relapsed while receiving fluoroquinolones. Repeat biopsy isolated multidrug-resistant, mucosally invasive E. coli in the ileum (1/2) and colon (2/2). Targeted antimicrobial therapy was associated with long-term PR (78 months) in both dogs.

CLINICAL SIGNIFICANCE

Concurrent E. coli-associated granulomatous inflammation in the ileum and colon did not impart a poor clinical outcome or lack of response to the conventional standard of care for granulomatous colitis in dogs that were aggressively diagnosed and treated. Clinical outcome was influenced by antimicrobial resistance, with response dependent upon antimicrobial therapy informed by susceptibility testing.

Early Life Modifiable Exposures and Their Association With Owner Reported Inflammatory Bowel Disease Symptoms in Adult Dogs

Background: Inflammatory bowel disease (IBD) is an idiopathic multifactorial disease in humans and dogs, usually assigned to the interactions between genes, gut microbiota, diet, environment, and the immune system. We aimed to investigate the modifiable early life exposures associated with IBD in dogs.

Materials and Methods: The study data was extracted from the validated owner-reported DogRisk food frequency questionnaire. This was a cross-sectional questionnaire-based study that tested 21 different early life dietary and environmental, demographic and genetic variables for their association with IBD or not, in adult dogs. A total of 7,015 dogs participated in this study. The study covered early life periods; prenatal, neonatal, early, and late postnatal periods. Two feeding patterns, a non-processed meat-based diet (NPMD) and an ultra-processed carbohydrate-based diet (UPCD) were studied. Data was analyzed using logistic regression analysis with a backward stepwise deletion.

Results: From the final models we found that the NPMD during early and late postnatal periods were significantly associated with lower IBD risk later in life. The UPCD during the same periods was associated with a higher risk of IBD incidence. Also, the maternal diet during the neonatal period showed a non-significant trend of lower IBD risk in the offspring with the NPMD and a higher IBD risk with the UPCD. Additionally, the normal body weight of puppies during the first 6 months of age was associated with a lower risk of IBD in adulthood while, slim puppies associated significantly with IBD in adulthood. From the non-modifiable background variables, we identified the maternal history of IBD as the strongest risk factor for later incidence of IBD. Furthermore, male dogs were twice as likely to develop IBD as female dogs were.

Conclusions: It is reassuring for owners to know that they themselves can have an impact on their dog's health. A high-fat, low-carbohydrate NPMD exposure during early life, and a normal body condition in puppyhood were significantly associated with less IBD in adult dogs. The opposite was true for UPCD exposure and abnormal body condition score in 6 month old puppies.

Escherichia coli-associated granulomatous colitis in dogs treated according to antimicrobial susceptibility profiling

Background

Eradication of intramucosal Escherichia coli correlates with remission of periodic acid‐Schiff‐positive E coli‐associated granulomatous colitis (GC). Treatment failures attributed to multidrug resistant (MDR) bacteria necessitate alternative approaches.

Hypothesis/objectives

Determine clinical outcome of E coli‐associated GC in dogs treated based on antimicrobial susceptibility profiling and characterize E coli phylogeny and resistance mechanisms.

Animals

Twenty Boxers and 4 French Bulldogs with E coli‐associated GC.

Methods

Culture, antimicrobial susceptibility profiling, and molecular characterization of E coli were performed and response to treatment was evaluated.

Results

Initial biopsy sample culture yielded fluoroquinolone‐sensitive (FQ‐S) E coli from 9/24 dogs and fluoroquinolone‐resistant (FQ‐R) E coli from 15/24. All but 1 FQ‐R E coli were MDR with susceptibility to macrophage‐penetrating antimicrobials restricted to carbapenems in 13/15 dogs. Of 22/24 treated based on susceptibility profiling, 8/9 FQ‐S dogs had complete initial clinical response (CR) during fluoroquinolone (FQ) treatment, whereas 9/13 FQ‐R dogs had complete or partial response (PR) during meropenem or doxycycline treatment. In 5/9 FQ‐S and 12/13 FQ‐R dogs with follow‐up ≥3 months, CR was sustained in 5/5 FQ‐S (median, 25 months; range, 4‐46) whereas 6/12 FQ‐R had long‐term CR (median, 59 months; range 15‐102), 4/12 PR (median, 19 months; range, 5‐65), and 2/12 had no response (NR). Four dogs with long‐term follow‐up died within 4 years of diagnosis, including 2 euthanized for refractory colitis. Escherichia coli were genetically diverse. Fluoroquinolone resistance was associated with mutations in gyrA and parC, with plasmid‐mediated resistance less common.

Conclusions and Clinical Importance

Antimicrobial treatment guided by susceptibility profiling was associated with positive long‐term outcomes in >80% of cases. Fluoroquinolone‐resistance was widespread and not clonal. Further study is required to optimize treatment for dogs with MDR E coli‐associated GC.

Role of gut microbiota in dog and cat's health and diseases

Mammalian gastrointestinal tract is colonized by a large number of microorganisms, known as gut microbiota, that play a key role in the physiological and pathological states. In particular, the gastrointestinal tract of dogs and cats harbors a complex and highly biodiverse microbial ecosystem. Recent studies see it involved in a wide range of life processes, including energy needs, metabolism, immunological activity, and neuro-behavioral development. This review focuses on the role of the microbiota on the health of pets and will discuss changes that occur in the disease.

Role of the gastrointestinal microbiota in small animal health and disease

There is a large and emerging interest in the role of the gastrointestinal microbiota in health and disease. This paper serves to review the current knowledge and recommendations of the gastrointestinal microbiota in health and gastrointestinal disease. Further, this review evaluates the current literature and suggests guidelines for faecal microbial transplantation, a novel therapy for dysbiosis in veterinary medicine.

Proper use of Quinolones for canine colitis ambulatory treatment: literature review and REQUEST guidelines

The literature analysed by REQUEST (REassesing QUinolone European STandard) using inclusion and exclusion criteria allows to make the conclusion that the proper use of fluoroquinolones (FQ) in canine colitis requires rigorously performed qualification to specific antimicrobial treatment. An infectious agent responsive to FQ therapy plays an integral role in the clinical manifestation of canine colitis, especially histiocytic ulcerative colitis (HUC) in young Boxer dogs. This supports the use of FQ in these cases. The Request guidelines for proper use of FQ in canine colitis is established, according to the available literature data.

Association between granulomatous colitis in French Bulldogs and invasive Escherichia coli and response to fluoroquinolone antimicrobials

BACKGROUND

French Bulldogs develop a form of granulomatous colitis (GC) with histopathological resemblance to GC of Boxer dogs (GCB). GCB is associated with mucosally invasive Escherichia coli whose eradication correlates with clinical remission.

HYPOTHESIS/OBJECTIVES

To characterize the clinical and histopathological features, presence or absence of invasive colonic bacteria, and response to fluoroquinolones in French Bulldogs with GC.

ANIMALS

A total of 6 French Bulldogs with a histological diagnosis of GC.

METHODS

Retrospective study of medical records. Bacterial colonization was evaluated using 16S rRNA probes for eubacteria and E. coli. Biopsy specimens from 3 dogs were cultured for bacteria. Clinical response to fluoroquinolone antimicrobials was determined.

RESULTS

All dogs were ≤1 year of age with hematochezia that was refractory to empirical therapy. Clinicopathologic and fecal analysis did not reveal abnormalities. Abdominal ultrasound revealed patchy thickening of the colon in 4/5 dogs and regional lymphadenopathy in 5/5. Colonoscopic abnormalities included irregularly thickened and ulcerated mucosa, hyperemia, and overt bleeding in 4/6 cases. Multifocal accumulations of PAS-positive macrophages and intramucosal E. coli were present in colonic biopsies of all 6 dogs. Administration of enrofloxacin (5/6) or marbofloxacin (1/6) at 4.4-10 mg/kg (median 10 mg/kg) PO q24h for 6-10 weeks was associated with clinical improvement within 5-14 days. All dogs remained in remission over a 3-30 month follow-up period.

CONCLUSIONS

Granulomatous colitis in young French Bulldogs is associated with the presence of invasive E. coli and closely parallels GCB. Treatment with fluoroquinolone antimicrobials can induce lasting clinical remission.

Granulomatous colitis of boxer dogs

Granulomatous colitis (GC) is a rare, breed-specific inflammatory bowel disease of young Boxer dogs. GC has been refractory to treatment and associated with high mortality rates, but culture-independent molecular analysis has transformed therapy and prognosis by uncovering a correlation between GC and Escherichia coli invasion within colonic mucosal macrophages. GC-associated invasive E coli are similar to a newly identified E coli pathotype, "adherent and invasive E coli," that are increasingly associated with Crohn's disease in humans. Successful treatment of GC requires antimicrobials that are effective against E coli and penetrate intracellularly. Enrofloxacin is widely regarded as the antibiotic of choice.

Laboratory tests for the diagnosis and management of chronic canine and feline enteropathies

Chronic enteropathies are commonly encountered in both cats and dogs. Although definitive diagnosis often requires collection of gastrointestinal biopsies for histopathologic evaluation, less invasive laboratory tests can be highly informative and should be performed prior to biopsy collection. Tests for determination of infectious causes comprise those for helminthic, protozoal, bacterial, or fungal organisms. Intestinal function and disease may be assessed by measuring serum concentrations of cobalamin, folate, and C-reactive protein, and fecal concentrations of α(1)-proteinase inhibitor. Ongoing research has led to development of tests for serum perinuclear antineutrophilic cytoplasmic antibodies, and fecal inflammatory markers, including S100-proteins and N-methylhistamine.

Antimicrobial resistance impacts clinical outcome of granulomatous colitis in boxer dogs

BACKGROUND

Escherichia coli have recently been identified within the colonic mucosa of Boxer dogs with granulomatous colitis (GC). Eradication of invasive E. coli is associated with clinical and histological remission.

OBJECTIVES

To determine antimicrobial susceptibility profiles of E. coli strains from GC and healthy dogs, and the association of antimicrobial resistance with clinical outcome.

ANIMALS

Fourteen Boxer dogs with GC and 17 healthy pet dogs.

METHODS

Prospective study: E. coli was cultured from GC biopsies and rectal mucosal swabs of healthy dogs. Individual strains were selected by phylogroup and overall genotype, determined by triplex- and random amplified polymorphic DNA-polymerase chain reaction respectively. Antimicrobial susceptibility was determined by broth microdilution minimal inhibitory concentration.

RESULTS

Culture yielded 23 E. coli strains from GC (1-3/dog, median 2) and 34 strains from healthy (1-3/dog, median 2). E. coli phylogroups were similar (P=.18) in GC (5A, 7B1, 5B2, 6D) and healthy (2A, 10B1, 15B2, 7D). Resistance to ampicillin, amoxicillin-clavulanate, cefoxitin, tetracycline, trimethoprim-sulfa (TMS), ciprofloxacin, and chloramphenicol was greater (P<.05) in GC (21-64%) than healthy (0-24%). Enrofloxacin resistant E. coli were isolated from 6/14 GC versus 0/17 healthy (P=.004). Of the enrofloxacin resistant cases, 4/6 were also resistant to macrophage-penetrating antimicrobials such as chloramphenicol, rifampicin, and TMS. Enrofloxacin treatment before definitive diagnosis was associated with antimicrobial resistance (P<.01) and poor clinical outcome (P<.01).

CONCLUSIONS AND CLINICAL IMPORTANCE

Antimicrobial resistance is common among GC-associated E. coli and impacts clinical response. Antimicrobial therapy should be guided by mucosal culture and antimicrobial susceptibility testing rather than empirical wisdom.

Inflammatory bowel disease in the dog: Differences and similarities with humans

Inflammatory bowel diseases (IBD) represent important chronic conditions affecting the gastrointestinal tract in man. However, similar disorders are found in several animal species and the IBD affecting dogs are particularly important. These are encompassed by an umbrella of probably several different entities with common symptoms, some of which seem to share striking similarities with human conditions. This review will focus on the actual knowledge of IBD in dogs, and attempt to identify differences and similarities with human IBD conditions.

Remission of histiocytic ulcerative colitis in Boxer dogs correlates with eradication of invasive intramucosal Escherichia coli

BACKGROUND

Historically, histiocytic ulcerative (HUC) (or granulomatous) colitis of Boxer dogs was considered an idiopathic immune-mediated disease with a poor prognosis. Recent reports of dramatic responses to enrofloxacin and the discovery of invasive Escherichia coli within the colonic mucosa of affected Boxer dogs support an infectious etiology.

HYPOTHESIS

Invasive E. coli is associated with colonic inflammation in Boxer dogs with HUC, and eradication of intramucosal E. coli correlates with clinical and histologic remission.

ANIMALS

Seven Boxer dogs with HUC.

METHODS

Prospective case series. Colonic biopsies were obtained at initial evaluation in 7 dogs, and in 5 dogs after treatment with enrofloxacin. Biopsies were evaluated by standardized histopathology, and fluorescence in situ hybridization (FISH) with probes to eubacteria and E. coli.

RESULTS

Intramucosal E. coli was present in colonic biopsies of 7/7 Boxers with HUC. Clinical response was noted in all dogs within 2 weeks of enrofloxacin (7 + or - 3.06 mg/kg q24 h, for 9.5 + or - 3.98 weeks) and was sustained in 6 dogs (median disease-free interval to date of 47 months, range 17-62). FISH was negative for E. coli in 4/5 dogs after enrofloxacin. E. coli resistant to enrofloxacin were present in the FISH-positive dog that relapsed.

CONCLUSIONS AND CLINICAL RELEVANCE

The correlation between clinical remission and the eradication of mucosally invasive E. coli during treatment with enrofloxacin supports the causal involvement of E. coli in the development of HUC in susceptible Boxer dogs. A poor response to enrofloxacin treatment might be due to colonization with enrofloxacin-resistant E. coli.

Protothecosis in 17 Australian dogs and a review of the canine literature

Systemic protothecosis was diagnosed in 17 Australian dogs between 1988 and 2005. There was a preponderance of young-adult (median 4 years), medium- to large-breed dogs. Females (12/17 cases) and Boxer dogs (7 cases, including 6 purebreds and one Boxer cross) were over-represented. Sixteen of 17 dogs died, with a median survival of four months. A disproportionate number of cases were from coastal Queensland. In most patients, first signs were referable to colitis (11/17 cases), which varied in severity, and was often present for many months before other symptoms developed. Subsequent to dissemination, signs were mostly ocular (12 cases) and/or neurologic (8 cases). Two dogs had signs due to bony lesions. Once dissemination was evident, death or euthanasia transpired quickly. Prototheca organisms had a tropism for the eye, central nervous system (CNS), bone, kidneys and myocardium, tissues with a good blood supply. Microscopic examination and culture of urine (5 cases), cerebrospinal fluid (CSF;1 case), rectal scrapings (4 cases), aspirates or biopsies of eyes (5 cases) and histology of colonic biopsies (6 cases) as well as skin and lymph nodes (2 cases) helped secure a diagnosis. Of the cases where culture was successful, P wickerhamii was isolated from two patients, while P zopfii was isolated from five. P zopfii infections had a more aggressive course. Treatment was not attempted in most cases. Combination therapy with amphotericin B and itraconazole proved effective in two cases, although in one of these treatment should have been for a longer duration. One surviving dog is currently still receiving itraconazole. Protothecosis should be considered in all dogs with refractory colitis, especially in female Boxers.

Adherent and invasive Escherichia coli is associated with granulomatous colitis in boxer dogs

The mucosa-associated microflora is increasingly considered to play a pivotal role in the pathogenesis of inflammatory bowel disease. This study explored the possibility that an abnormal mucosal flora is involved in the etiopathogenesis of granulomatous colitis of Boxer dogs (GCB). Colonic biopsy samples from affected dogs (n = 13) and controls (n = 38) were examined by fluorescent in situ hybridization (FISH) with a eubacterial 16S rRNA probe. Culture, 16S ribosomal DNA sequencing, and histochemistry were used to guide subsequent FISH. GCB-associated Escherichia coli isolates were evaluated for their ability to invade and persist in cultured epithelial cells and macrophages as well as for serotype, phylogenetic group, genome size, overall genotype, and presence of virulence genes. Intramucosal gram-negative coccobacilli were present in 100% of GCB samples but not controls. Invasive bacteria hybridized with FISH probes to E. coli. Three of four GCB-associated E. coli isolates adhered to, invaded, and replicated within cultured epithelial cells. Invasion triggered a "splash"-type response, was decreased by cytochalasin D, genistein, colchicine, and wortmannin, and paralleled the behavior of the Crohn's disease-associated strain E. coli LF 82. GCB E. coli and LF 82 were diverse in serotype and overall genotype but similar in phylogeny (B2 and D), in virulence gene profiles (fyuA, irp1, irp2, chuA, fepC, ibeA, kpsMII, iss), in having a larger genome size than commensal E. coli, and in the presence of novel multilocus sequence types. We conclude that GCB is associated with selective intramucosal colonization by E. coli. E. coli strains associated with GCB and Crohn's disease have an adherent and invasive phenotype and novel multilocus sequence types and resemble E. coli associated with extraintestinal disease in phylogeny and virulence gene profile.

Pharmacokinetic and pharmacodynamic interactions of tolfenamic acid and marbofloxacin in goats

Pharmacokinetic and pharmacodynamic properties in goats of the non-steroidal anti-inflammatory drug tolfenamic acid (TA), administered both alone and in combination with the fluoroquinolone marbofloxacin (MB), were established in a tissue cage model of acute inflammation. Both drugs were injected intramuscularly at a dose rate of 2 mg kg(-1). After administration of TA alone and TA+MB pharmacokinetic parameters of TA (mean values) were Cmax=1.635 and 1.125 microg ml(-1), AUC=6.451 and 3.967 microgh ml(-1), t1/2K10=2.618 and 2.291 h, Vdarea/F=1.390 and 1.725Lkg(-1), and ClB/F=0.386 and 0.552 L kg(-1) h(-1), respectively. These differences were not statistically significant. Tolfenamic acid inhibited prostaglandin (PG)E2 synthesis in vivo in inflammatory exudate by 53-86% for up to 48 h after both TA treatments. Inhibition of synthesis of serum thromboxane (Tx)B2 ex vivo ranged from 16% to 66% up to 12h after both TA and TA+MB, with no significant differences between the two treatments. From the pharmacokinetic and eicosanoid inhibition data for TA, pharmacodynamic parameters after dosing with TA alone for serum TxB2 and exudate PGE2 expressing efficacy (Emax=69.4 and 89.7%), potency (IC50=0.717 and 0.073 microg ml(-1)), sensitivity (N=3.413 and 1.180) and equilibration time (t1/2Ke0=0.702 and 16.52 h), respectively, were determined by PK-PD modeling using an effect compartment model. In this model TA was a preferential inhibitor of COX-2 (COX-1:COX-2 IC50 ratio=12:1). Tolfenamic acid, both alone and co-administered with MB, did not affect leucocyte numbers in exudate, transudate or blood. Compared to placebo significant attenuation of skin temperature rise over inflamed tissue cages was obtained after administration of TA and TA+MB with no significant differences between the two treatments. Marbofloxacin alone did not significantly affect serum TxB2 and exudate PGE2 concentrations or rise in skin temperature over exudate tissue cages. These data provide a basis for the rational use of TA in combination with MB in goat medicine.