Identification of Mucosa-Invading and Intravascular Bacteria in Feline Small Intestinal Lymphoma

Histologic characterization of the major duodenal papilla and association with concurrent biliary, pancreatic, and intestinal pathology in cats

Conjoining of the major pancreatic duct and common bile duct at the major duodenal papilla (MDP) is suspected to predispose cats to the clinical syndrome of "triaditis." However, microanatomy of the MDP or presence of lesions at the MDP has not been assessed in cats with or without triaditis. The aims of this study were to characterize feline MDP histomorphology and to identify associations between MDP anatomy/disease and the presence of biliary, pancreatic, or intestinal inflammation or neoplasia. Histologic assessment was prospectively performed on the MDP, duodenum, jejunum, ileum, liver, and pancreas from 124 client-owned cats undergoing postmortem examination. The majority of cats (104/124, 84%) had a complex ductular network at the MDP, with no distinction between pancreatic and common bile ducts. Lymphoid aggregates at the MDP were common (63/124, 51%). Inflammation of the MDP (MDPitis) was present in 35 of 124 cats (28%) and was often concurrent with cholangitis, pancreatitis, or enteritis (32/35, 91%), but was only associated with enteritis (19/35, 54%, P < .05). Triaditis was less common (19/124, 15%), but was associated with both conjoined MDP anatomy (19/19, 100%, P < .05) and MDPitis (12/19, 63%, P < .05). Neoplasia was present in 37 of 124 cats (29%), with lymphoma (28/37, 78%) predominating. Enteropathy-associated T-cell lymphoma type 2 (EATL2) was most common (n = 16/37, 43%) and was associated with triaditis and MDPitis (P < .05). These findings suggest that anatomy, immune activation, and/or inflammation of the MDP may play a role in the pathogenesis of triaditis. Further studies are needed to elucidate the relationships between triaditis, MDPitis, and EATL2.

Fluorescent In Situ Hybridization for the Detection of Intracellular Bacteria in Companion Animals

FISH techniques have been applied for the visualization and identification of intracellular bacteria in companion animal species. Most frequently, these techniques have focused on the identification of adhesive-invasive Escherichia coli in gastrointestinal disease, although various other organisms have been identified in inflammatory or neoplastic gastrointestinal disease. Previous studies have investigated a potential role of Helicobacter spp. in inflammatory gastrointestinal and hepatic conditions. Other studies evaluating the role of infectious organisms in hepatopathies have received some attention with mixed results. FISH techniques using both eubacterial and species-specific probes have been applied in inflammatory cardiovascular, urinary, and cutaneous diseases to screen for intracellular bacteria. This review summarizes the results of these studies.

ACVIM consensus statement guidelines on diagnosing and distinguishing low-grade neoplastic from inflammatory lymphocytic chronic enteropathies in cats

BACKGROUND

Lymphoplasmacytic enteritis (LPE) and low-grade intestinal T cell lymphoma (LGITL) are common diseases in older cats, but their diagnosis and differentiation remain challenging.

OBJECTIVES

To summarize the current literature on etiopathogenesis and diagnosis of LPE and LGITL in cats and provide guidance on the differentiation between LPE and LGITL in cats. To provide statements established using evidence-based approaches or where such evidence is lacking, statements based on consensus of experts in the field.

ANIMALS

None.

METHODS

A panel of 6 experts in the field (2 internists, 1 radiologist, 1 anatomic pathologist, 1 clonality expert, 1 oncologist) with the support of a human medical immunologist, was formed to assess and summarize evidence in the peer-reviewed literature and complement it with consensus recommendations.

RESULTS

Despite increasing interest on the topic for clinicians and pathologists, few prospective studies were available, and interpretation of the pertinent literature often was challenging because of the heterogeneity of the cases. Most recommendations by the panel were supported by a moderate or low level of evidence. Several understudied areas were identified, including cellular markers using immunohistochemistry, genomics, and transcriptomic studies.

CONCLUSIONS AND CLINICAL IMPORTANCE

To date, no single diagnostic criterion or known biomarker reliably differentiates inflammatory lesions from neoplastic lymphoproliferations in the intestinal tract of cats and a diagnosis currently is established by integrating all available clinical and diagnostic data. Histopathology remains the mainstay to better differentiate LPE from LGITL in cats with chronic enteropathy.

Infectious Causes of Neoplasia in the Domestic Cat

In recent years, growing attention has been paid to the influence/role of infectious diseases in tumour development and progression. Investigations have demonstrated that some infectious organisms can have a direct role in the development of neoplasia, whereas others can predispose to neoplasia by alterations in the immune response, or by creating a pro-inflammatory environment. Feline leukaemia virus was one of the first infectious agents recognised as an oncogenic organism, and along with feline immunodeficiency virus has received the most attention. Since the discovery of this retrovirus, several other organisms have been associated with neoplastic processes in cats, these include gammaherpes virus, mouse mammary tumour virus, papillomaviruses, hepadnavirus, Helicobacter species, and the parasitic infections Platynosomum fastosum and Opisthorchis viverrini. This review summarises the findings to date.

Short- and long-term effects of amoxicillin/clavulanic acid or doxycycline on the gastrointestinal microbiome of growing cats

Antibiotic treatment in early life influences gastrointestinal (GI) microbial composition and function. In humans, the resultant intestinal dysbiosis is associated with an increased risk for certain diseases later in life. The objective of this study was to determine the temporal effects of antibiotic treatment on the GI microbiome of young cats. Fecal samples were collected from cats randomly allocated to receive either amoxicillin/clavulanic acid (20 mg/kg q12h) for 20 days (AMC group; 15 cats) or doxycycline (10 mg/kg q24h) for 28 days (DOX group;15 cats) as part of the standard treatment of upper respiratory tract infection. In addition, feces were collected from healthy control cats (CON group;15 cats). All cats were approximately two months of age at enrolment. Samples were collected on days 0 (baseline), 20 or 28 (AMC and DOX, respectively; last day of treatment), 60, 120, and 300. DNA was extracted and sequencing of the 16S rRNA gene and qPCR assays were performed. Fecal microbial composition was different on the last day of treatment for AMC cats, and 1 month after the end of antibiotic treatment for DOX cats, compared to CON cats. Species richness was significantly greater in DOX cats compared to CON cats on the last day of treatment. Abundance of Enterobacteriales was increased, and that of Erysipelotrichi was decreased in cats of the AMC group on the last day of treatment compared to CON cats. The abundance of the phylum Proteobacteria was increased in cats of the DOX group on days 60 and 120 compared to cats of the CON group. Only minor differences in abundances between the treatment groups and the control group were present on day 300. Both antibiotics appear to delay the developmental progression of the microbiome, and this effect is more profound during treatment with amoxicillin/clavulanic acid and one month after treatment with doxycycline. Future studies are required to determine if these changes influence microbiome function and whether they have possible effects on disease susceptibility in cats.

Serum haptoglobin concentrations in feline inflammatory bowel disease and small-cell alimentary lymphoma: a potential biomarker for feline chronic enteropathies

OBJECTIVES

The aim of this study was to evaluate serum haptoglobin as a biomarker to differentiate between small-cell alimentary lymphoma and inflammatory bowel disease in cats.

METHODS

Client-owned domestic cats with and without chronic gastrointestinal signs were enrolled in the study. Serum was collected from each patient and serum haptoglobin levels were measured using ELISA. In cats with gastrointestinal signs, histopathologic evaluation of endoscopic biopsies harvested from the intestinal tract was used to separate them into inflammatory bowel disease and small-cell lymphoma cohorts. Serum haptoglobin levels were statistically analyzed and compared among the three groups: healthy cats; cats with inflammatory bowel disease; and cats with small-cell alimentary lymphoma.

RESULTS

Sixty-two cats were enrolled in the study, including 20 clinically normal cats, 14 cats with small-cell alimentary lymphoma and 28 cats with inflammatory bowel disease. The mean ± SD serum haptoglobin was 73.2 ± 39.1 mg/dl in normal cats, 115.3 ± 72.8 mg/dl in cats with inflammatory bowel disease and 133.1 ± 86.1 mg/dl in cats with small-cell alimentary lymphoma. Cats with inflammatory bowel disease and lymphoma had significantly higher serum haptoglobin than controls, with P values of 0.0382 and 0.0138, respectively. There was no statistical difference between the inflammatory bowel disease and lymphoma cohorts (P = 0.4235). For every one unit increase in serum haptoglobin, the odds of gastrointestinal inflammatory disease (inflammatory bowel disease or small-cell alimentary lymphoma) increased by 1.41% (P = 0.0165).

CONCLUSIONS AND RELEVANCE

Serum haptoglobin is a useful biomarker for distinguishing between normal cats and those with gastrointestinal inflammatory disease, but it could not significantly differentiate between inflammatory bowel disease and lymphoma. Additional studies may be beneficial in determining the prognostic significance of serum haptoglobin as it may relate to the severity of gastrointestinal inflammation.

Pilot study of the effect of gastrointestinal diets on fecal occult blood testing in cats

OBJECTIVES

The aim of this study was to assess the methodology of guaiac-based fecal occult blood (FOB) testing in healthy cats, and to examine the effect of feeding selected gastrointestinal diets (canned and dry) on FOB results.

METHODS

Stool obtained from three cats was mixed with incremental quantities of EDTA whole blood. FOB tests were performed in triplicate and interpreted at 5 mins, and at 24, 48 and 72 h post-test set-up. Ten cats were fed their normal diets, a dry hydrolyzed protein diet, a dry gastrointestinal diet and then transitioned back to their normal diet over a 7-week period. A subsequent study was repeated with similar hydrolyzed protein and gastrointestinal canned diets. Two fecal samples were tested per cat each week using human point-of-care guaiac tests.

RESULTS

Ten microliters of whole feline blood could be reliably detected in feline stool at all time points evaluated. There was no evidence of an association between the dry hydrolyzed and dry gastrointestinal diets and a positive FOB test result (P = 0.33). Cats fed a canned gastrointestinal diet had a significantly higher probability of producing a positive FOB result than when on their normal diet (P <0.01). Feeding the canned hydrolyzed diet was not associated with an increased probability of a positive FOB test vs the normal diet (P = 0.94).

CONCLUSIONS AND RELEVANCE

Small amounts of blood in feline stool can be reliably and repeatedly detected as early as 5 mins post-FOB test set-up, making this a user-friendly bench-top screening test in a veterinary setting. Cats fed a single dry hydrolyzed, dry gastroenteric or canned hydrolyzed diet in this study had a low chance of false-positive FOB test results, while those fed the canned gastrointestinal diet had a significantly greater likelihood of producing false-positive results.

Feline low-grade alimentary lymphoma: an emerging entity and a potential animal model for human disease

BACKGROUND

Low-grade alimentary lymphoma (LGAL) is characterised by the infiltration of neoplastic T-lymphocytes, typically in the small intestine. The incidence of LGAL has increased over the last ten years and it is now the most frequent digestive neoplasia in cats and comprises 60 to 75% of gastrointestinal lymphoma cases. Given that LGAL shares common clinical, paraclinical and ultrasonographic features with inflammatory bowel diseases, establishing a diagnosis is challenging. A review was designed to summarise current knowledge of the pathogenesis, diagnosis, prognosis and treatment of feline LGAL. Electronic searches of PubMed and Science Direct were carried out without date or language restrictions.

RESULTS

A total of 176 peer-reviewed documents were identified and most of which were published in the last twenty years. 130 studies were found from the veterinary literature and 46 from the human medicine literature. Heterogeneity of study designs and outcome measures made meta-analysis inappropriate. The pathophysiology of feline LGAL still needs to be elucidated, not least the putative roles of infectious agents, environmental factors as well as genetic events. The most common therapeutic strategy is combination treatment with prednisolone and chlorambucil, and prolonged remission can often be achieved. Developments in immunohistochemical analysis and clonality testing have improved the confidence of clinicians in obtaining a correct diagnosis between LGAL and IBD. The condition shares similarities with some diseases in humans, especially human indolent T-cell lymphoproliferative disorder of the gastrointestinal tract.

CONCLUSIONS

The pathophysiology of feline LGAL still needs to be elucidated and prospective studies as well as standardisation of therapeutic strategies are needed. A combination of conventional histopathology and immunohistochemistry remains the current gold-standard test, but clinicians should be cautious about reclassifying cats previously diagnosed with IBD to lymphoma on the basis of clonality testing. Importantly, feline LGAL could be considered to be a potential animal model for indolent digestive T-cell lymphoproliferative disorder, a rare condition in human medicine.

Relationship of the mucosal microbiota to gastrointestinal inflammation and small cell intestinal lymphoma in cats

Background

The gastrointestinal (GI) microbiota in healthy cats is altered in IBD. Little research has been performed to identify whether specific bacterial groups are associated with small cell GI lymphoma (LSA).

Hypothesis

Mucosal bacteria, including Enterobacteriaceae and Fusobacterium spp., are abundant in intestinal biopsies of cats with small cell GI LSA compared to cats with IBD.

Animals

Fourteen cats with IBD and 14 cats with small cell GI LSA.

Methods

Retrospective case control study. A search of the medical records was performed to identify cats diagnosed with IBD and with GI LSA. Bacterial groups identified by FISH in GI biopsies were compared between cohorts and correlated to CD11b⁺ and NF‐κB expression.

Results

Fusobacterium spp. (median; IQR bacteria/region) were higher in cats with small cell GI LSA in ileal (527; 455.5 – 661.5; P = .046) and colonic (404.5; 328.8 – 455.5; P = .016) adherent mucus, and combined colonic compartments (free mucus, adherent mucus, attaching to epithelium) (8; 0 – 336; P = .017) compared to cats with IBD (ileum: 67; 31.5 – 259; colon: 142.5; 82.3 – 434.5; combined: 3; 0 – 34). Bacteroides spp. were higher in ileal adherent mucus (P = .036) and 3 combined ileal compartments (P = .034) of cats with small cell GI LSA. There were significant correlations between Fusobacterium spp. totals and CD11b⁺ cell (P = .009; rs .476) and NF‐κB expression (P = .004; rs .523).

Conclusions

The bacterial alterations appreciated might be influential in development of small cell GI LSA, and should drive further studies to elucidate the effects of microbial‐mediated inflammation on GI cancer progression.