Introduction: Canine protein-losing enteropathy (PLE) is a syndrome characterized by gastrointestinal loss of proteins. While fecal microbiome and metabolome perturbations have been reported in dogs with chronic enteropathy, they have not been widely studied in dogs with PLE. Therefore, the study aims were to investigate gut microbiome and targeted fecal metabolites in dogs with inflammatory PLE (iPLE) and evaluate whether treatment affects these changes at short-term follow-up.Methods: Thirty-eight dogs with PLE and histopathological evidence of gastrointestinal inflammation and 47 healthy dogs were enrolled. Fecal samples were collected before endoscopy (T0) and after one month of therapy (T1). Microbiome and metabolome alterations were investigated using qPCR assays (dysbiosis index, DI) and gas chromatography/mass spectrometry (long-chain fatty acids, sterols, unconjugated bile acids), respectively.Results: Median (min-max) DI of iPLE dogs was 0.4 (−5.9 to 7.7) and was significantly higher (p < 0.0001) than median DI in healthy dogs [−2.0 (−6.0 to 5.3)]. No significant associations were found between DI and selected clinicopathological variables. DI did not significantly differ between T0 and T1. In iPLE dogs, at T0, myristic, palmitic, linoleic, oleic, cis-vaccenic, stearic, arachidonic, gondoic, docosanoic, erucic, and nervonic acids were significantly higher (p < 0.0001) than healthy dogs. In iPLE dogs, oleic acid (p = 0.044), stearic acid (p = 0.013), erucic acid (p = 0.018) and nervonic acid (p = 0.002) were significantly decreased at T1. At T0, cholesterol and lathosterol (p < 0.0001) were significantly higher in iPLE dogs compared to healthy dogs, while total measured phytosterols were significantly lower (p = 0.001). No significant differences in total sterols, total phytosterols and total zoosterols content were found at T1, compared to T0. At T0, total primary bile acids and total secondary bile acids did not significantly differ between healthy control dogs and iPLE dogs. No significant differences in fecal bile acid content were found at T1.Discussion: Dysbiosis and lipid metabolism perturbations were observed in dogs with iPLE. Different therapeutic protocols lead to an improvement of some but not all metabolome perturbations at short-term follow-up.

Few routinely available biomarkers are clinically useful in assessing dogs with inflammatory protein-losing enteropathy caused by immunosuppressive-responsive enteropathy (IRE-PLE). Only the neutrophil to lymphocyte ratio (NLR) has been studied, while no information exists on the use of the albumin to globulin ratio (AGR) and C-reactive protein to albumin ratio (CRP/ALB). We aimed to evaluate the clinical significance of the NLR, AGR and CRP/ALB in a population of dogs with IRE-PLE. The medical records of 53 IRE-PLE dogs were reviewed at the time of diagnosis (T0) and 1 month after the initiation of immunosuppressants (T1). A control group of 68 healthy dogs was used for comparison. At T0, the median values of the NLR and AGR of sick dogs were significantly higher and lower than those of healthy dogs, respectively. With the increase in the chronic enteropathy activity index, AGR and CRP/ALB significantly decreased and increased, respectively. At T1, NLR and AGR significantly increased, while CRP/ALB significantly decreased. NLR, AGR and CRP/ALB did not differ significantly between dogs classified as responders and nonresponders according to the chronic enteropathy activity index. Further studies are needed to provide more information on this subject.

Chronic inflammation alters lipoprotein metabolism and causes changes in the serum concentrations of lipids, C-reactive protein (CRP), and paraoxonase-1 activity (PON-1), an enzyme that may act as a local detoxifier, antioxidant, and immunomodulator in the gastrointestinal tract. Scarce information is available in dogs with protein-losing enteropathy secondary to chronic enteropathy (iPLE). The first aim was to describe and compare the lipid profiles, CRP concentrations and PON-1 activities in healthy dogs and in dogs with iPLE. The second aim was to evaluate correlations among clinicopathological, histologic data and lipid profiles in dogs with iPLE. Serum samples from 51 iPLE and 40 healthy dogs were used to study albumin, total protein, CRP, PON-1 activity, cholesterol, triglycerides and lipoprotein classes. Serum concentrations of albumin, total protein, cholesterol, PON-1 activity, and high-density and very-low-density lipoproteins were lower in iPLE dogs compared to healthy controls, while those of triglycerides, low-density lipoproteins, chylomicrons and CRP were higher. Significant correlations between the lipid profile and the existing chronic enteropathy activity index were not found. High-density and low-density lipoproteins correlated with CRP and PON-1. Triglycerides were significantly higher in dogs with both inflammation and lymphangiectasia. The results need to be confirmed in further studies.

Chronic inflammation alters lipoprotein metabolism and causes changes in serum concentrations of lipids, C-reactive protein (CRP), and paraoxonase-1 activity (PON-1), an enzyme, which in the gastrointestinal tract may act as a local detoxifier, antioxidant, and immunomodulator. However, unlike in people with inflammatory bowel disease, scarce information is available in dogs with protein-losing enteropathy secondary to chronic inflammatory enteropathy (iPLE). The first aim was to describe and compare the lipid profile, CRP concentrations and PON-1 activity in healthy dogs and in dogs with iPLE. The second aim was to evaluate correlations among clinicopathological, histologic data, and lipid profiles in dogs with iPLE. Serum samples from 51 iPLE and 40 healthy dogs were used to study albumin, total protein, CRP, PON-1 activity, cholesterol, triglycerides, and lipoprotein classes obtained by electrophoretic separation. There was a significant difference of all serum analytes between iPLE and healthy dogs. Significant correlations between the lipid profile and the existing chronic enteropathy activity index were not found. Some lipoprotein classes correlated with CRP and PON-1. Triglycerides were significantly higher in dogs with both inflammation and lymphangiectasia. Lipoproteins, CRP and PON-1 activity are altered in dogs with iPLE. Results need to be confirmed in further studies.

Intravenous iodinated contrast (IVIC) medium is routinely administered to dogs. Scattered information exists regarding the serum biochemical or urinary profiles associated with the administration of IVIC in dogs. The aim of the study was to describe, compare, and discuss from the perspective of previous studies the alterations in serum biochemical and urinary parameters before (T0) and within one week (T1) of the IVIC administration during routine computed tomography (CT) scan evaluation of 22 dogs. Mature dogs presenting for CT scan evaluation for preoperative oncology staging/surgical planning were included. T1 evaluation was performed within one week of IVIC administration. Statistically significant differences in serum total protein, albumin, chloride, calcium, and phosphorus concentrations, urine protein to creatinine ratio, and urine specific gravity were found between T1 and T0. At T1, the serum creatinine concentration was within reference ranges in all dogs but one. An increase in the urine protein to creatinine ratio was observed in four samples, one of which was non-proteinuric at T0. Changes in biochemistry and urine parameters between T0 and T1 were not considered clinically significant.

Alterations in fat-soluble vitamins are well documented in humans with inflammatory bowel disease; however, data in dogs with chronic enteropathy and inflammatory protein-losing enteropathy (iPLE) are limited. This prospective case–control study compared serum concentrations of vitamins A, D, and E metabolites in dogs with iPLE and healthy controls and evaluated associations with selected clinicopathological variables at diagnosis (T0) and after one month of therapy (T1). Fifty-eight dogs with iPLE and 50 healthy dogs were enrolled. Twenty dogs with iPLE were available for evaluation at T1. iPLE was defined by chronic gastrointestinal signs, hypoalbuminemia of gastrointestinal origin, and histologic evidence of benign intestinal inflammation with or without lymphangiectasia. Serum retinol, 25-hydroxyvitamin D, and α-tocopherol concentrations were measured by HPLC at T0 and T1. At T0, all vitamin concentrations were significantly lower in iPLE dogs (p < 0.0001). A weak positive correlation was found between retinol and α-tocopherol concentrations. No differences were observed according to treatment, diet, or histopathologic findings. At T1, retinol concentrations increased (p = 0.01), whereas vitamin D and E metabolite concentrations did not. Dogs fed homemade low-fat diets had lower vitamin D concentrations. These findings indicate decreased serum concentrations of multiple fat-soluble vitamins in dogs with iPLE, suggesting altered fat-soluble vitamin homeostasis, with only partial recovery after treatment.