Comparative pathophysiology and management of protein-losing enteropathy

The effect of assisted enteral feeding on treatment outcome in dogs with inflammatory protein-losing enteropathy

BACKGROUND

The effect of assisted enteral feeding on treatment outcome in dogs with protein-losing enteropathy (PLE) is unknown.

OBJECTIVES

To determine if dogs with inflammatory PLE that had an enteral feeding tube placed had better outcome vs dogs with inflammatory PLE without a feeding tube.

ANIMALS

Fifty-seven dogs with inflammatory PLE.

METHODS

A retrospective study at a UK referral hospital identified dogs with inflammatory PLE using a standard diagnostic criterion. Positive outcome was defined as survival greater than 6 months or death unrelated to PLE and negative outcome as death related to PLE within 6 months of diagnosis. Several variables were assessed to identify factors for positive outcome using logistic regression.

RESULTS

Thirty-five (61%) and 22 (39%) dogs had a positive and negative outcome at 6 months, respectively. Of the 21 dogs that had a feeding tube placed within 5 days of gastrointestinal biopsy, 16 (76%) had a positive outcome and 5 (24%) had a negative outcome. Dogs treated with dietary treatment alone (P = .002) and dogs with an enteral feeding tube (P = .006) were significantly associated with a positive outcome. When stratified by treatment, assisted enteral feeding was significantly associated with a positive outcome in dogs treated with concurrent immunosuppressive treatment (P = .006), but there was insufficient data to evaluate dogs treated with dietary treatment alone.

CONCLUSIONS AND CLINICAL IMPORTANCE

Assisted enteral feeding in dogs with inflammatory PLE could be associated with improved treatment outcome, especially in those receiving immunosuppressive treatment, and should be considered in the treatment plan of these dogs.

Prospective evaluation of a change in dietary therapy in dogs with steroid-resistant protein-losing enteropathy

OBJECTIVE

To describe the clinical effect of dietary alteration as a sole change to therapy in dogs with steroid-resistant protein-losing enteropathy.

MATERIALS AND METHODS

Prospective study. Eligible enrolled dogs received dietary alteration as sole change to their therapeutic plan. Canine Chronic Enteropathy Clinical Activity Index and serum albumin were monitored for the 3-month study period. Long-term follow-up data were also available for some of the study participants.

RESULTS

Fifteen dogs were eligible for enrollment over the study period. Twelve were enrolled, 10 remained in the study at 30 days, nine completed the 3-month study period. Following dietary alteration, eight of 10 dogs achieved complete remission, one dog achieved partial remission and one dog had no response. Seven of eight dogs achieving complete remission have remained in remission up to 4 years following study. In dogs with complete remission, median Canine Chronic Enteropathy Clinical Activity Index score was 11.5 and 4, and median serum albumin concentration was 15 g/L and 26 g/L at 0 and 14-28 days, respectively.

CLINICAL SIGNIFICANCE

Dogs with protein-losing enteropathy with previous lack of response to a combination of dietary therapies, glucocorticoids and immunosuppressive medications can achieve remission following a dietary change. Improvement is likely to be seen within 14 to 30 days. A change in dietary approach may be an alternative to further immunosuppression or anti-inflammatory strategies in some dogs with difficult to treat protein-losing enteropathy.

Blood neutrophil-to-lymphocyte ratio (NLR) as a diagnostic marker in dogs with chronic enteropathy

Few routinely available biomarkers are clinically useful in assessing dogs with chronic enteropathy (CE) and aid in CE subclassification. The diagnostic potential of the blood neutrophil-to-lymphocyte ratio (NLR) has not been evaluated in canine CE. We evaluated the NLR in 93 dogs with CE (no steroid treatment for ≥2 wk prior) and tested for an association with clinical, clinicopathologic, and histologic characteristics and also with CE subclassification. NLR was significantly higher in CE dogs with severe clinical disease than dogs with mild clinical disease (p = 0.047). Hypoalbuminemia (p < 0.001), but not hypocobalaminemia, was associated with higher NLRs. NLR was correlated with fecal alpha₁-proteinase inhibitor concentrations (ρ = 0.47) and the serum-to-fecal alpha₁-proteinase inhibitor ratio (ρ = -0.48; both p < 0.001) but not with serum or fecal inflammatory markers nor with the overall histologic score (all p > 0.05). Dogs with steroid- or other immunosuppressant-responsive (IRE) or nonresponsive enteropathy (NRE) had significantly higher NLRs (median: 7.3) than dogs with food-responsive enteropathy (FRE; median: 3.0; p = 0.003), and a NLR ≥5.5 best distinguished both groups of dogs. No difference in NLR was detected between dogs with IRE and dogs diagnosed with NRE. These findings suggest that leukogram changes (i.e., NLR) could be clinically useful in canine CE, and that neutrophils might play a role in the systemic inflammatory response associated with canine CE. The NLR can be easily assessed on routine hematology and can potentially aid in the subclassification of dogs with CE based on the response to treatment.

Platelet abnormalities and platelet-to-lymphocyte ratios in canine immunosuppressant-responsive and non-responsive enteropathy: A retrospective study in 41 dogs

Few studies have examined platelet alterations in dogs with chronic enteropathy. Our aim was to investigate platelet count (PLT), mean platelet volume (MPV), and platelet-to-lymphocyte ratio (PLR) in dogs diagnosed with immunosuppressant-responsive enteropathy (IRE). In this retrospective study of 41 dogs, data regarding signalment, canine chronic enteropathy clinical activity index (CCECAI), endoscopic and histopathological scores, PLT, MPV, PLR, total serum protein concentrations, albumin, and iron were collected. Clinical response and relapse were assessed with the evaluation of CCECAI over time. One month after starting therapy, dogs with >25% CCECAI reduction were considered responders. During a three-month CCECAI evaluation as part of a twelve-month follow-up, a CCECAI >3 together with a ≥2 unit increase in responder dogs was considered a relapse. PLT and PLR displayed significant negative correlation with MPV. MPV was positively correlated with total protein and albumin levels and negatively correlated with CCECAI. Three dogs were classified as non-responders, and 14 relapsed within 12 months. No differences were observed in PLT, MPV, or PLR between responding/non-responding and relapsing/non-relapsing groups. PLT, MPV, and PLR correlated with total protein, albumin, and CCECAI, confirming PLT as a potential marker, and suggesting MPV as a new marker of clinical efficacy against canine IRE.

Successful management of portal vein thrombosis in a Yorkshire Terrier with protein-losing enteropathy

Background

Portal vein thrombosis (PVT) is a rare presentation in dogs with protein-losing enteropathy (PLE). Rivaroxaban, an oral, selective, direct factor Xa inhibitor, has not been reported to be administrated for canine PVT and the effect is unclear in dogs with PLE.

Case presentation

An 11-year-old Yorkshire Terrier presented with moderate ascites. The dog had severe hypoalbuminemia (1.2 g/dL), and a portal vein thrombus was confirmed on computed tomographic angiography (CTA). On endoscopic examination, it became apparent that the hypoalbuminemia was caused by PLE, which was consequent of lymphatic dilation and lymphoplasmacytic enteritis. Therefore, the dog was initially treated with oral administrations of spironolactone and clopidogrel, with dietary fat restriction. However, a follow-up CTA showed no changes in the ascites, thrombus, and portal vein to aorta (PV/Ao) ratio. Therefore, the dog was additionally prescribed rivaroxaban and low-dose prednisolone for the portal vein thrombus and hypoalbuminemia due to lymphoplasmacytic enteritis, respectively. Following the treatment, the PV/Ao ratio decreased because of a decrease in the thrombus and the ascites disappeared completely with an elevation of albumin concentration (1.9 g/dL).

Conclusions

This case report demonstrated that oral administration of rivaroxaban combined with low-dose glucocorticoid was effective management for PVT in a dog with PLE.

Canine Protein Losing Enteropathies and Systemic Complications

Canine protein-losing enteropathies occur commonly in small animal practice, and their management is often challenging with a long-term survival rate of only about 50%. Recent studies have investigated prognostic factors that may determine outcome in individual cases. In particular, systemic complications such as hypercoagulability, vitamin D3 deficiency, and tryptophan deficiency may play an important role and should be investigated in severely affected cases in order to maximize outcome.

Neutrophil-to-Lymphocyte Ratio (NLR) in Canine Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is a multifactorial chronic inflammatory disorder leading to structural changes in the intestinal wall. In humans, the neutrophil-to-lymphocyte ratio (NLR) has been proposed as a promising marker of IBD. This study evaluated the possible clinical and prognostic significance of the NLR in dogs with IBD. This retrospective study enrolled 41 dogs diagnosed with IBD presented to University of Pisa from January 2017 to January 2018. For each dog, age, sex, canine chronic enteropathy clinical activity index (CCECAI), endoscopic and histopathological grading were recorded. Complete blood count, serum total protein, albumin, cholesterol, and C-reactive protein at the time of endoscopy were recorded. A control group (CG) of healthy dogs from a blood donor database was built. NLR was calculated for both IBD and CG as the ratio between absolute neutrophils and lymphocytes. Presence of crypt distension, lacteal dilation (LD), mucosal fibrosis, intraepithelial lymphocytes was recorded. Follow-up information was obtained from electronic medical records and dogs were classified as responders and non-responders based on CCECAI variation between admission and the first recheck. IRE dogs showed higher NLR compared to healthy dogs. NLR correlated negatively with total protein, albumin, and cholesterol and correlated positively with CCECAI. Dogs with LD showed higher NLR than dogs without LD. Non-responders showed higher NLR compared to responders. In conclusion, as in IBD human patients, the NLR acts as an inflammatory marker providing further information on severity of the disease and could be useful in predicting treatment response.

Clinical characteristics of dogs with food-responsive protein-losing enteropathy

Background

In dogs with protein‐losing enteropathy (PLE), data on the clinical characteristics of food‐responsive PLE (FR‐PLE) remain scarce.

Objective

To determine the clinical characteristics of FR‐PLE in dogs responsive to ultralow‐fat diet (ULFD) management.

Animals

Thirty‐three dogs diagnosed with PLE based on standard diagnostic criteria.

Methods

Retrospective review of medical records. Clinical findings were compared between dogs with FR‐PLE (FR‐PLE group) and those with immunosuppressant‐responsive PLE (IR‐PLE) or nonresponsive PLE (NR‐PLE) (IR/NR‐PLE group). The area under the curve (AUC) of a receiver operating characteristic curve was used to evaluate the ability of factors to differentiate the FR‐PLE and IR/NR‐PLE groups. Survival time was compared between the FR‐PLE and IR/NR‐PLE groups.

Results

Twenty‐three dogs responded to ULFD management and were diagnosed with FR‐PLE. The canine chronic enteropathy clinical activity index (CCECAI) was significantly lower in the FR‐PLE group than in the IR/NR‐PLE group (P < .001). The AUC of CCECAI for differentiating the FR‐PLE group was 0.935 (95% confidence interval [CI], 0.845‐1.000) with an optimal cutoff value of 8 (sensitivity, 0.826; specificity, 0.889). Survival times were significantly longer in the FR‐PLE group (median, not reached) than in the IR/NR‐PLE group (median, 432 days; P < .001).

Conclusions and Clinical Importance

Dogs that respond to ULFD management and are diagnosed with FR‐PLE are expected to have a favorable prognosis. Clinical scores, specifically the CCECAI, could be useful for differentiating FR‐PLE from IR‐PLE or NR‐PLE.

Ki-67/CD3 ratio in the diagnosis of chronic inflammatory enteropathy in dogs

BACKGROUND

T cells play a key role in the pathogenesis of chronic inflammatory enteropathy (CIE) in dogs. Cluster of differentiation 3 (CD3) antigen serves as a marker for T cells. In human medicine, Ki-67 is an indicator for cell growth but there are only a few studies in dogs with CIE.

OBJECTIVE

To investigate Ki-67 in relation to T cells as a marker for CIE in dogs.

ANIMALS

Eleven dogs with CIE and 6 healthy beagle controls (CO).

METHODS

Retrospective case-control study. Dogs were clinically assessed by the Canine Chronic Enteropathy Clinical Activity Index (CCECAI). Duodenal mucosal biopsy samples were endoscopically obtained for histopathologic examination by means of the World Small Animal Veterinary Association score. Double-labeled immunofluorescence was used to investigate colocalization of Ki-67 and CD3 in epithelium and lamina propria (LP) of villi and crypts.

RESULTS

Dogs with CIE had significantly higher clinical score (median, 5.0; interquartile range [IQR], 3-7) compared to CO (all 0; P < .001). The Ki-67/CD3 double-positive cells were significantly increased in the LP of the crypt region of CIE dogs (0.63 cells/mm² ; IQR, 0-0.54) versus CO (0.08 cells/mm² ; IQR, 0-0.26; P = .044). A significant correlation was found between CCECAI and the Ki-67/CD3 ratio in the LP of the crypt region (r = 0.670; P = .012) in dogs with CIE.

CONCLUSIONS AND CLINICAL IMPORTANCE

The Ki-67/CD3 ratio is upregulated in the LP crypt region of dogs with CIE and it correlates with clinical severity. Therefore, Ki-67/CD3 could be a useful tool for detection of CIE.

Diagnostic features, treatment, and outcome of dogs with inflammatory protein-losing enteropathy

Background

Protein‐losing enteropathy (PLE) because of chronic inflammatory enteropathy (CIE) in dogs is often treated with a combination of glucocorticoids and second‐line immunosuppressant (SLI). This combined approach might not be necessary in all dogs.

Hypothesis/objectives

To describe diagnostic features and outcomes of dogs with PLE treated with glucocorticoids alone (group P) or with glucocorticoids and SLI (group S).

Animals

Thirty‐one dogs with PLE.

Material and methods

Retrospective analysis of signalment data from diagnostic procedures, treatment, and outcome of dogs with CIE/PLE (from 2015 to 2017), using the hospital's digital case database. Dogs with hypoalbuminemia and CIE were included. Because of a stepwise treatment algorithm, dogs were allocated to group P or S. Time to serum albumin concentrations ≥20 g/L and survival data were collected. Dogs were additionally categorized by their albumin and cobalamin serum concentrations. Multivariate and univariate analysis as well as Pearson's correlation and Kaplan‐Maier survival analysis were performed.

Results

Seventeen dogs were included in group P and 14 in group S. World Small Animal Veterinary Association score of the duodenum was different between groups (P = .05), but none of the other examined data. Median time until serum albumin reached >20 g/L was 13 days. Median survival time after start of treatment was 85 days (range, 13‐463 days) in group P and 166 days (range, 8‐390 days) in group S.

Conclusion and Clinical Importance

No routine diagnostic test was predictive of clinical response, treatment group, or outcome. Glucocorticoid treatment alone can be appropriate in dogs with PLE.

Comparative pathophysiology and management of protein-losing enteropathy

Protein‐losing enteropathy, or PLE, is not a disease but a syndrome that develops in numerous disease states of differing etiologies and often involving the lymphatic system, such as lymphangiectasia and lymphangitis in dogs. The pathophysiology of lymphatic disease is incompletely understood, and the disease is challenging to manage. Understanding of PLE mechanisms requires knowledge of lymphatic system structure and function, which are reviewed here. The mechanisms of enteric protein loss in PLE are identical in dogs and people, irrespective of the underlying cause. In people, PLE is usually associated with primary intestinal lymphangiectasia, suspected to arise from genetic susceptibility, or “idiopathic” lymphatic vascular obstruction. In dogs, PLE is most often a feature of inflammatory bowel disease (IBD), and less frequently intestinal lymphangiectasia, although it is not proven which process is the true driving defect. In cats, PLE is relatively rare. Review of the veterinary literature (1977‐2018) reveals that PLE was life‐ending in 54.2% of dogs compared to published disease‐associated deaths in IBD of <20%, implying that PLE is not merely a continuum of IBD spectrum pathophysiology. In people, diet is the cornerstone of management, whereas dogs are often treated with immunosuppression for causes of PLE including lymphangiectasia, lymphangitis, and crypt disease. Currently, however, there is no scientific, extrapolated, or evidence‐based support for an autoimmune or immune‐mediated mechanism. Moreover, people with PLE have disease‐associated loss of immune function, including lymphopenia, severe CD4+ T‐cell depletion, and negative vaccinal titers. Comparison of PLE in people and dogs is undertaken here, and theories in treatment of PLE are presented.