The role of acute phase proteins in diagnosis and management of steroid-responsive meningitis arteritis in dogs

Quantitative proteomics analysis of cerebrospinal fluid reveals putative protein biomarkers for canine non-infectious meningoencephalomyelitis

Accurate ante-mortem diagnosis of non-infectious meningoencephalomyelitis (NIME) in dogs is challenging due to the similarity of clinical presentations, imaging findings, and cerebrospinal fluid (CSF) analysis results with other diseases. This study aimed to apply state-of-the-art quantitative proteomic technology to identify novel biomarkers for NIME. Serum and CSF samples from 11 dogs were included, with the control group consisting of patients presenting with intervertebral disc disease (IVDD, n = 6) and the study group consisting of dogs suffering from NIME (n = 5). Mass spectrometry-based quantitative proteomics revealed a set of 36 proteins with significant differential abundance in CSF samples. Up-regulated proteins in NIME CSF included immunoglobulins, inter-alpha-trypsin inhibitor heavy chain 2, acid sphingomyelinase-like phosphodiesterase, and chitinase 3-like protein 1, all associated with immune response and inflammation. Conversely, significantly down-regulated proteins included neural cell adhesion molecule, contactin-1, and procollagen C-endopeptidase enhancer, which are involved in neurodevelopment and synaptic plasticity. No differences in serum profiles were observed among the groups. This study identified a panel of CSF protein biomarker candidates for NIME and provided new insights into the pathogenesis of the disease, suggesting that neuronal dysfunction and immune dysregulation may be involved.

Diagnostic Utility of Canine C-Reactive Protein, Haptoglobin, and 25-Hydroxyvitamin-D in Dogs with Nasal Cavity Disease

In this prospective blinded study, canine C-reactive protein (c-CRP), haptoglobin (HPT), and 25-hydroxyvitamin-D (25(OH)D) were investigated for their diagnostic value in 55 dogs with nasal cavity disease (ND). After comprehensive diagnostics including a culture-dependent microbiological examination (ME) of nasal swabs, 17 dogs were excluded due to additionally detected systemic diseases or steroid pre-treatment. Included were 25 dogs with malignant ND (13 carcinomas and 12 sarcomas) and 30 dogs with benign ND (7 benign tumors, 13 idiopathic rhinitis (IR), and 10 others), as well as 10 controls. In none of the 72 dogs with ND was primary bacterial rhinitis diagnosed. Although within the reference interval, compared to the controls, c-CRP was significantly higher in dogs with ND in general and in every subgroup except for benign tumors. Serum HPT concentrations were not different among groups. Compared to the controls, 25(OH)D concentrations were significantly lower (p = 0.041) in malignant ND and sarcomas (p = 0.025). Despite pre-treatment with antibiotics (40/54; 74.1%), in 23/51 (45%) dogs, the ME was positive. Cultivated bacteria did not differ significantly between nasal diseases. The serum markers were not significantly different regarding the positivity of ME. In conclusion, the investigated serum markers were not clinically useful for the reliable detection of canine ND, as was the ME. Because of the low number of dogs with IR and positive or negative ME, further studies regarding c-CRP are needed in a larger group of IR dogs without concomitant diseases to reliably evaluate its utility in IR dogs with suspected secondary bacterial nasal infection.

High-Dose Hydrocortisone Treatment Does Not Affect Serum C-Reactive Protein (CRP) Concentrations in Healthy Dogs

Measuring C-reactive protein (CRP) in serum is a useful surrogate marker for assessing disease progression and treatment response in dogs with autoinflammatory diseases. Affected dogs often receive high-dose glucocorticoid treatment, but the effect of such treatment alone on serum CRP concentrations is unknown. We evaluated serum CRP concentrations via immunoassay (sandwich enzyme-linked immunosorbent assay and particle-enhanced turbidimetric immunoassay) in 12 healthy beagle dogs administered high-dose hydrocortisone (8 mg/kg q12 h) per os vs. placebo over 28 days (days 0, 1, 5, and 28) in a randomized parallel study design. Serum CRP concentrations slightly decreased during treatment or placebo but without a significant association with hydrocortisone administration (p = 0.761). Compared to baseline, serum CRP concentrations were decreased by >2.7-fold (minimum critical difference) in three hydrocortisone-treated dogs and two dogs in the placebo group on day 28, whereas an increase to >2.7-fold was seen in one dog receiving placebo. These results suggest a lack of confounding effects of high-dose hydrocortisone administration on serum CRP concentrations in healthy dogs. This might also hold in dogs with autoinflammatory conditions and/or administration of other high-dose corticosteroids, suggesting that CRP presents a suitable biomarker to monitor inflammatory disease processes. However, this needs confirmation by further studies evaluating corticosteroid-induced cellular (e.g., hepatic) transcriptome and proteome changes.

Steroid-responsive meningitis-arteritis: What have we learned since 2010? A narrative review

Steroid-responsive meningitis-arteritis (SRMA) occurs as an immune-mediated, inflammatory, and non-infectious disorder of juvenile and young-adult dogs. In principle, SRMA is divided into two clinical courses: during the typical acute form, dogs are presented with fever, cervical hyperaesthesia, and reluctance to move. The more protracted form most probably emerges after insufficient immunosuppressive treatment or relapses, with additional neurologic deficits localized in the cervical and thoracolumbar spinal cord or multifocally. The trigger leading to SRMA still remains an unsolved riddle for immunologists and clinical neurologists. In the past, many attempts have been made to clarify the etiology of this disease without success. The purpose of writing this narrative review about SRMA is to summarize new insights on the pathogenesis of SRMA with a focus on immunologic dysregulation. Furthermore, unusual manifestations of the disease, new diagnostic approaches using possible laboratory biomarkers or diagnostic imaging tools, and potential innovative treatment strategies are discussed.

Elevated Interleukin-31 Levels in Serum, but Not CSF of Dogs with Steroid-Responsive Meningitis-Arteritis Suggest an Involvement in Its Pathogenesis

Steroid-responsive meningitis-arteritis (SRMA) is a predominantly Th-2 immune-mediated disease, but the exact pathomechanism remains unclear. Interleukin-31 (IL-31) is predominantly produced by T cells with a Th-2 phenotype during proinflammatory conditions. We hypothesize that IL-31 might be involved in the pathogenesis of SRMA. IL-31 was measured in archived samples (49 serum and 52 CSF samples) of dogs with SRMA, meningoencephalitis of unknown origin (MUO), infectious meningoencephalitis, and atopic dermatitis, and of healthy control dogs using a competitive canine IL-31 ELISA. The mean serum IL-31 level in dogs with SRMA (n = 18) was mildly higher compared to dogs with atopic dermatitis (n = 3, p = 0.8135) and MUO (n = 15, p = 0.7618) and markedly higher than in healthy controls (n = 10, p = 0.1327) and dogs with infectious meningoencephalitis (n = 3, no statistics). Dogs with SRMA in the acute stage of the disease and without any pre-treatment had the highest IL-31 levels. The mean CSF IL-31 value for dogs with SRMA (n = 23) was quite similar to that for healthy controls (n = 8, p = 0.4454) and did not differ markedly from dogs with MUO (n = 19, p = 0.8724) and infectious meningoencephalitis. Based on this study, an involvement of IL-31 in the pathogenesis of the systemic Th-2 immune-mediated immune response in SRMA can be assumed as a further component leading to an aberrant immune reaction.

MicroRNA profiling of cerebrospinal fluid from dogs with steroid responsive meningitis-arteritis and meningoencephalitis of unknown origin

Introduction

Non-infectious inflammatory diseases of the central nervous system in dogs, such as steroid responsive meningitis-arteritis (SRMA) and meningoencephalitis of unknown origin (MUO), represent a common clinical challenge that needs extensive and multimodal work-up to reach a presumptive diagnosis. Both diseases are presumably caused by dysregulations of the immune system, but further research is needed in order to understand the molecular mechanisms behind each disease and to optimize treatment.

Methods

By next-generation sequencing and subsequent quantitative real-time PCR (qPCR) verification, we designed a prospective case-control pilot study to analyze the small RNA profiles of cerebrospinal fluid from dogs suffering from MUO (N = 5), dogs suffering from SRMA (N = 8), and healthy dogs (N = 5) presented for elective euthanasia used as the Control group.

Results

Our results showed an overall enrichment in Y-RNA fragments across all samples, followed by microRNAs (miRNAs) and ribosomal RNAs as the major findings. Additional traces of short RNA reads mapped to long non-coding RNAs and protein-coding genes were also found. From the detected canine miRNAs, miR-21, miR-486, miR-148a, miR-99a, miR-191 and miR-92a were among the most abundant. Dogs with SRMA showed higher differences in miRNA abundance than dogs with MUO when compared to healthy dogs, and miR-142-3p was consistently detected as differentially upregulated in both diseases, although at a low concentration. Moreover, miR-405-5p and miR-503-5p showed different profiles between SRMA and MUO dogs. Subsequent qPCR analyses confirmed miR-142-5p, miR-191-5p and miR-92a-3p as significantly upregulated miRNAs in dogs with SRMA and/or MUO.

Discussion

Cerebrospinal fluid is a challenging biological material to use for profiling miRNAs due to the low content of circulating RNAs. Despite this, we could confirm several miRNAs being differentially abundant when comparing healthy dogs and dogs with MUO and SRMA, respectively. The results of this study indicate a potential role of miRNAs in the underlying molecular mechanisms of these diseases and establish the basis for further studies.

Evaluation of serum 25-hydroxyvitamin D, C-reactive protein, and haptoglobin as biomarkers in dogs newly diagnosed with histoplasmosis

BACKGROUND

Serum 25-hydroxyvitamin (OH)D, C-reactive protein (CRP), and haptoglobin are useful biomarkers in various infectious diseases and inflammatory disorders in dogs, but their utility in histoplasmosis is unknown.

OBJECTIVE

Determine if serum 25(OH)D, CRP, and haptoglobin concentrations are different in dogs with histoplasmosis compared to healthy controls and whether serum globulin, albumin, CRP, or haptoglobin are associated with 25(OH)D concentration.

ANIMALS

Twenty-two client-owned dogs (histoplasmosis, n = 12; controls, n = 10).

METHODS

Prospective case-control study. Dogs with histoplasmosis were categorized as pulmonary, disseminated, or gastrointestinal (GI) tract. Serum 25(OH)D was measured using modified high-performance liquid chromatography (HPLC). Serum CRP and haptoglobin were measured with ELISA assays.

RESULTS

Dogs with histoplasmosis were grouped as disseminated (n = 8) and GI tract (n = 4). No dogs had pulmonary tract involvement alone. Dogs with histoplasmosis (median, interquartile range [IQR]; 11.6 ng/mL, 16.8) had lower serum 25(OH)D concentrations than controls (35.7 ng/mL, 17.6; P < .001). Serum CRP and haptoglobin concentrations were higher in dogs with histoplasmosis (CRP: median, IQR; 63.5 mg/L, 37.1 and haptoglobin: 459.7 mg/dL, 419.6) than controls (CRP: 1.9 mg/L, 2; P < .001 and haptoglobin: 85.5 mg/dL, 106.7; P = .003). Serum 25(OH)D concentration was positively associated with fold change in serum albumin concentration (ρ = 0.77; P < .001), and negatively associated with fold change in serum globulin (ρ = -0.61; P = .003) and CRP concentrations (ρ = -0.56; P = .01).

CONCLUSION AND CLINICAL IMPORTANCE

Assay of serum 25(OH)D, CRP, and haptoglobin could have clinical value in dogs with histoplasmosis.

Immunoglobulin profiling with large high-density peptide microarrays as screening method to detect candidate proteins for future biomarker detection in dogs with steroid-responsive meningitis-arteritis

Steroid responsive meningitis arteritis (SRMA) is an aberrant Th2-mediated systemic inflammatory disease in dogs. The etiopathogenesis still remains unclear as no triggering pathogen or autoantigen could be found so far.

HYPOTHESIS

Large high-density peptide microarrays are a suitable screening method to detect possible autoantigens which might be involved in the pathogenesis of SRMA.

METHODS

The IgA and IgG profile of pooled serum samples of 5 dogs with SRMA and 5 dogs with neck pain due to intervertebral disc herniation (IVDH) without ataxia or paresis were compared via commercially available high-density peptide microarrays (Discovery Microarray) containing 29,240 random linear peptides. Canine distemper virus nucleoprotein (CDVN) served as positive control as all dogs were vaccinated. Common motifs were compared to amino acid sequences of known proteins via databank search. One suitable protein was manually selected for further analysis with a smaller customized high-density peptide microarray.

RESULTS

Pooled serum of dogs with SRMA and IVDH showed different IgA and IgG responses on Discovery Microarray. Only top IgG responses of dogs with SRMA showed a common motif not related to the control protein CDVN. This common motif is part of the interleukin 1 receptor antagonist protein (IL1Ra). On IL1Ra, dogs with SRMA displayed IgA binding to an additional epitope, which dogs with IVDH did not show.

DISCUSSION

IL1Ra is an anti-inflammatory acute phase protein. Different immunoglobulin binding patterns on IL1Ra could be involved in the pathogenesis of SRMA and IL1Ra might be developed as future biomarker for SRMA.

Magnetic resonance imaging highlights the meningeal involvement in steroid responsive meningitis-arteritis and suggests the inflammation of the surrounding tissues (70 cases)

Introduction

Steroid-responsive meningitis-arteritis (SRMA) is an immune-mediated disorder of young dogs for which there is no definitive ante-mortem diagnostic test. Magnetic Resonance Imaging (MRI) can be used to explore other differentials and extensive reports about its usefulness in the diagnosis of SRMA are lacking. The aims of this study were to retrospectively investigate the characteristics of MRI studies of the cervical spine of dogs diagnosed with SRMA and to compare the diagnostic capability of MRI obtained with low-field and high-field units.

Materials and methods

This is a double center, retrospective case series. Databases were searched between 2008 and 2021 for dogs with a diagnosis of SRMA. Dogs were included if the following criteria were fulfilled: a diagnosis of cervical SRMA, results of CSF analysis, and MRI of the cervical spine available for re-evaluation.

Results

Seventy cases were selected. MRI abnormalities were found in 69 cases (98.6%). Enhancement of the meninges, nerve roots, synovium of the articular facets and paravertebral muscles was present in 61 (87.1%), 10 (14.3%), 34 (48.6%), and 34 (48.6%) cases, respectively, when considering all MRI. In the low-field MRI, enhancement of these structures was present in 45 (90%), 4 (8%), 21 (42%) and 23 (46%) cases, respectively. In the high-field MRI, enhancement of these structures was present in 16 (80%), 6 (30%), 13 (65%) and 11 (55%) cases, respectively. Fat suppressed T1W images showed meningeal enhancement better than T1W images. When all the MRIs were considered, a significant increase in cell count of the cerebrospinal fluid was found between the three groups based on the meningeal MRI score (p = 0.001). In cases with no meningeal enhancement but enhancement of synovium of the articular facets and/or muscles a significantly lower cerebrospinal fluid cell count was present (p = 0.043), when considering all MRIs.

Conclusions

The most frequent detection on cervical MRI of dogs affected by SRMA is meningeal enhancement, often accompanied by enhancement of the synovium of the articular facets and/or muscular enhancement. Both low-field and high-field MRI have good diagnostic capability but the latter enables a more thorough investigation thanks to specific sequences. MRI is useful as a complementary tool to cerebrospinal fluid analysis.

Serial evaluation of thoracic radiographs and acute phase proteins in dogs with pneumonia

Background

Acute phase proteins (APP) may guide treatment of pneumonia in dogs but correlations with radiographic abnormalities are poorly characterized.

Objectives

Develop a thoracic radiographic severity scoring system (TRSS), assess correlation of radiographic changes with APP concentrations, and compare time to APP and radiograph normalization with duration of antimicrobials treatment.

Animals

Sixteen client‐owned dogs, 12 with aspiration pneumonia, and 4 with community‐acquired pneumonia.

Methods

Concentrations of C‐reactive protein (CRP), serum amyloid A (SAA), and haptoglobin were measured on days 1, 3, 7, 14, 28, and 60 and orthogonal 2‐view thoracic radiographs were obtained on days 1, 7, 14, 28, and 60. Treatment was clinician‐guided and blinded to APP concentrations. Radiographic severity scores were assigned by blinded, randomized retrospective review by 2 board‐certified radiologists with arbitration by a third radiologist.

Results

Median (interquartile range [IQR]) time to normalization of CRP (7 days [7‐14]) and SAA concentrations (7 days [7‐14]) were shorter than antimicrobial treatment duration (17.5 days [14.5‐33.5]; P = .001 and .002, respectively) and TRSS normalization (14 days [8.8‐52], P = .02 and .02, respectively). The CRP and SAA concentrations were positively correlated with TRSS (CRP r_s, 0.643; SAA r_s, 0.634; both P < .0001). Both CRP and SAA identified normal thoracic radiographs area under the curve (AUC) 0.873 and 0.817, respectively, both P < .0001. Interobserver agreement for TRSS assignment was moderate (κ, .499; P < .0001).

Conclusion and Clinical Importance

Concentrations of CRP and SAA normalized before radiographic resolution and before clinicians discontinued antimicrobial treatment. The CRP and SAA concentrations may guide duration of antimicrobial treatment for dogs with pneumonia.

Combination of Prednisolone and Azathioprine for Steroid-Responsive Meningitis-Arteritis Treatment in Dogs

Treatment with high corticosteroid dosages for steroid-responsive meningitis-arteritis (SRMA) is correlated with severe adverse effects and worse quality of life. In order to improve immunosuppression and decrease dosage and duration of glucocorticoid treatment, a second immunosuppressive drug is commonly used in most of the immune-mediated diseases. The objective of this retrospective study was to evaluate the efficacy, tolerability, and occurrence of relapse for the combination of prednisolone and azathioprine. All dogs received azathioprine 2 mg/kg q 24 hr for 1 mo and then 2 mg/kg every other day for 2 mo; prednisolone was started at an immunosuppressive dosage and tapered off gradually during a mean of 3 mo. Twenty-six dogs met inclusion criteria. Twenty-one dogs (81%) were in clinical remission with no relapse observed within the 2 yr follow-up period. Treatment was well tolerated in all dogs and side effects were most of the time mild and self-limiting. The relapse rate (19%) was lower than most published rates. A prednisolone and azathioprine combination appeared to be effective for primary treatment of dogs with SRMA and allows a quicker tapering in prednisolone dosage, a decrease in long-term side effects of steroids, a shorter duration of treatment, and a low relapse rate.

Differential acute-phase protein responses in dogs seropositive or seronegative for Neospora caninum

Neospora caninum is one of the most prevalent Apicomplexa parasites that causes abortion in cattle, as it infects dogs as its definitive host, causing subclinical disease or active neosporosis, marked by meningoencephalitis, and myopathies with muscle and neuromuscular signs of disease. This study aimed to evaluate the acute phase protein response in dogs seropositive and seronegative for N. caninum. Serum samples of 72 dogs were tested by an immunofluorescence antibody test using N. caninum NC-1 strain, and the study population was divided into four groups: symptomatic - muscular and/or neuromuscular signs - and seropositive (n = 16); symptomatic and seronegative (n = 9); asymptomatic and seropositive (n = 34); and asymptomatic and seronegative (n = 13). C-reactive protein (CRP) was measured via immunoturbidimetric assay and serum haptoglobin (Hp) via hemoglobin-binding capacity assay. In the symptomatic groups, seropositive dogs had higher levels of Hp, but not CRP, while seronegative dogs had higher CRP levels. There was no difference in CRP concentration in asymptomatic dogs. Dogs with neuromuscular signs had higher concentrations for Hp in the group seropositive. Hp concentration did not differ between dogs seropositive and seronegative dogs for each group. Serum Hp and CRP could not sufficiently alone flag subclinical infections. Measurement of CRP and Hp concentrations could be clinically valuable to the diagnosis of neurological diseases, and their relative change may indicate the stage of the infection, although their sole use is not able to support the diagnosis of canine neosporosis. Further studies are encouraged to evaluate the specific dynamics of acute phase proteins in canine neosporosis. Serum samples of 72 dogs were tested by an immunofluorescence antibody test using N. caninum NC-1 strain, and the study population was divided into four groups: (1) dogs with muscular and/or neuromuscular signs and seropositive for N. caninum; (2) dogs with muscular and/or neuromuscular signs and seronegative for N. caninum; (3) dogs seropositive for N. caninum with no neuromuscular signs; and (4) healthy dogs and seronegative for N. caninum. The study evaluated if N. caninum infection could have pathophysiological changes activating the acute phase response and an increase in the concentration of acute phase proteins in serum.

Serum C-reactive protein in dogs with paraplegia secondary to acute intervertebral disc extrusion

BACKGROUND

Apart from the absence of nociception, there is no readily available prognostic test for dogs presenting with paraplegia secondary to acute intervertebral disc extrusion (IVDE).

OBJECTIVE

To assess if serum C-reactive protein (CRP) can predict the postoperative outcome in paraplegic dogs undergoing surgery for IVDE and to assess the association between serum CRP and presence/absence of nociception on admission, and serum CRP and presence/absence of intramedullary changes seen on magnetic resonance imaging (MRI).

ANIMALS

One hundred dogs that underwent surgery at our hospital between 2018 and 2020 because of acute paraplegia secondary to IVDE and in which serum CRP was measured.

METHODS

Retrospective observational cohort study. Dogs were classified as 4 or 5 according to the modified Frankel score (MFS) depending on presence/absence of nociception, respectively. MRI images were reviewed and the T2-weighted hyperintensity: L2 vertebral body length was measured. Postoperative outcome was defined as positive if nociception, ambulation or both returned after decompressive surgery.

RESULTS

The median (95% CI) serum CRP was 4 (4-5) and 6 (4-7) mg/L in MSF4 and MSF5, respectively (P = .03). A weak linear relationship (R²  = 0.049, P = .03) was found between CRP and the T2-weighted hyperintensity: L2 vertebral length. Outcome data was available for 85 dogs: CRP was 4 (4-5) and 5 (4-10) mg/L in positive and negative outcome dogs, respectively (P = .32).

CONCLUSION AND CLINICAL IMPORTANCE

Serum CRP did not predict outcome after surgery in dogs with paraplegia secondary to IVDE.

Biomarkers of non-infectious inflammatory CNS diseases in dogs: Where are we now? Part 2 - Steroid responsive meningitis-arteritis

Steroid responsive meningitis-arteritis (SRMA) in dogs causes severe inflammation of meningeal arteries leading to generalized meningitis with possible neurological signs, as well as a systemic inflammatory response. The etiology and exact pathogenesis are unknown, but an immune-mediated origin has been suggested and is supported by a positive response to immunosuppressive treatment with corticosteroids. A collection of clinical and paraclinical characteristics may be highly indicative of SRMA, but a single and conclusive diagnostic test or biomarker is currently not available. The aim of this review is to provide an overview of the current understanding and knowledge on SRMA, with special emphasis on potential biomarkers and their applicability in the diagnostic work-up. Though no specific markers for SRMA currently exist, clinically useful markers include IgA and several acute phase proteins e.g. C-reactive protein. A frequent problem of both acknowledged and proposed biomarkers, is, however, their inability to effectively differentiate SRMA from other systemic inflammatory conditions. Other proposed diagnostic markers include genetic markers, acute phase proteins such as serum amyloid A, cytokines such as interleukin-17 and CC-motif ligand 19, endocannabinoid receptors and heat shock protein 70; these suggestions however either lack specificity or need further investigation.

Biomarkers of non-infectious inflammatory CNS diseases in dogs - Where are we now? Part I: Meningoencephalitis of unknown origin

Meningoencephalitides of Unknown Origin (MUO) comprises a group of non-infectious inflammatory brain conditions, which frequently cause severe neurological disease and death in dogs. Although multiple diagnostic markers have been investigated, a conclusive diagnosis, at present, essentially relies on postmortem histopathology. However, different groups of biomarkers, e.g. acute phase proteins, antibodies, cytokines, and neuro-imaging markers may prove useful in the diagnostic investigation of dogs with MUO. It appears from the current literature that acute phase proteins such as C-reactive protein are often normal in MUO, but may be useful to rule out steroid responsive meningitis-arteritis as well as other systemic inflammatory conditions. In antibody research, anti-glial fibrillary acidic protein (GFAP) may play a role, but further research is needed to establish this as a consistent marker of particularly Pug dog encephalitis. The proposed diagnostic markers often lack specificity to distinguish between the subtypes of MUO, but an increased expression of interferon-γ (IFN-γ) in necrotizing meningoencephalitis (NME) and interleukin-17 (IL-17) in granulomatous meningoencephalitis (GME) in tissue biopsies may indicate their potential as specific markers of NME and GME, respectively, suggesting further investigations of these in serum and CSF. While neuro-imaging is already an important part of the diagnostic work-up in MUO, further promising results have been shown with Positron Emission Tomography (PET) as well as proton resonance spectroscopy (¹H MRS), which may be able to detect areas of necrosis and granulomas, respectively, with relatively high specificity. This review presents different groups of established and potential diagnostic markers of MUO assessing current results and future potential.

From Bench Top to Clinics: How New Tests Can Be Helpful in Diagnosis and Management of Dogs with Chronic Enteropathies

In this article, we review different tests that have been researched in dogs with chronic enteropathy. The usefulness of these tests either to assess etiology, to differentiate between treatment response, or to monitor treatment response is discussed. The tests are divided in those that are commercially available and those that hold promises for further development.

Comparison of C-reactive protein concentrations in dogs with Bordetella bronchiseptica infection and aspiration bronchopneumonia

BACKGROUND

C-reactive protein (CRP) is a well-known acute-phase protein in dogs that may discriminate bacterial bronchopneumonia from other pulmonary conditions. Bronchopneumonia caused by Bordetella bronchiseptica (Bb) is common but the associated increase in CRP concentration in naturally infected dogs has not been fully explored.

OBJECTIVE

To compare CRP concentrations of dogs with Bb infection, with or without radiographic pulmonary lesions, to dogs with aspiration bronchopneumonia (ABP).

ANIMALS

Sixteen dogs with Bb infection and 36 dogs with ABP.

METHODS

Retrospective study. C-reactive protein concentrations and thoracic radiographs were available for each dog.

RESULTS

Eleven dogs with Bb infection had alveolar lesions. In all dogs, CRP concentration was mildly increased (14-38 mg/L). In the 5 dogs without alveolar lesions, CRP concentration was within the reference range in all but 1 dog, in which it was slightly increased. Median CRP concentration was significantly higher in dogs with alveolar lesions (20 mg/L) compared with dogs without alveolar lesions (5 mg/L; p < .002). In dogs with Bb infection, median duration of clinical signs was not different between dogs with normal CRP concentration and dogs with increased concentration. In dogs with Bb infection either with or without alveolar lessions, median CRP concentration was significantly lower (20 mg/L) than in dogs with ABP (118 mg/L; p < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

In contrast to dogs with APB, CRP was not a good marker for the diagnosis of dogs suspected to have bordetellosis. Confirmation of Bb infection still requires lower airway sampling.

Use of C-reactive protein concentration in evaluation of diskospondylitis in dogs

Background

C‐reactive protein (CRP) is a positive acute phase protein that increases in many inflammatory conditions of dogs. Serum CRP concentration has important diagnostic and prognostic utility in humans with vertebral osteomyelitis.

Hypothesis/objectives

To determine if a correlation exists between serum CRP concentration and clinical and magnetic resonance imaging (MRI) findings in dogs with diskospondylitis, and if CRP predicts prognosis.

Animals

Eighteen client‐owned dogs with MRI diagnosis of diskospondylitis.

Methods

Retrospective study evaluating signalment, clinical signs, neurologic examination findings, white blood cell count, neutrophil count, serum globulin concentration, serum CRP concentration, radiographic findings, MRI findings, bacterial culture results, and outcome in dogs with diskospondylitis.

Results

Serum CRP concentration was significantly more sensitive than were fever and leukocytosis for predicting the presence of diskospondylitis. Serum CRP concentration was more sensitive than neutrophilia and hyperglobulinemia. No difference in serum CRP concentration was found between dogs with single or multiple lesions, nor between dogs with or without empyema, muscular involvement or spinal cord compression. No association was found between serum CRP concentration and positive bacterial culture.

Conclusions and Clinical Importance

C‐reactive protein is a sensitive, but nonspecific biomarker for diskospondylitis which may prove useful as an adjunctive diagnostic test in patients with suspicious clinical signs and may help predict prognosis.

C-reactive protein in dogs with suspected bacterial diskospondylitis: 16 cases (2010-2019)

Objectives

C-reactive protein (CRP) is an acute phase protein used in multiple canine inflammatory conditions including steroid responsive meningitis-arteritis, immune-mediated polyarthritis and bronchopneumonia. The aim of this study was to assess whether serum CRP is elevated in cases of diskospondylitis.

Methods

Medical records from 2010 to 2019 were searched to identify dogs diagnosed with diskospondylitis based on findings consistent on CT or MRI and with CRP tested.

Results

A total of 16 dogs met the inclusion criteria. All cases had back pain. Fourteen cases had elevated CRP, with a median value of 100.7 mg/l (reference range for CRP values: 0-10 mg/l), 12 were pyrexic and six had leucocytosis. The two dogs with normal CRP were normothermic and did not have leucocytosis. CRP was measured four to six weeks into antimicrobial treatment in eight of 14 dogs and was normal in all cases. One dog developed a suspected bacterial empyema diagnosed on MRI; this occurred two weeks after antibiotic treatment was discontinued based on a normal CRP level at follow-up.

Conclusions

Serum CRP is elevated in cases of diskospondylitis and may be clinically more useful to screen dogs with back pain than pyrexia or leucocytosis alone. Further long-term clinical evaluation in a prospective study is needed to assess its use as a treatment monitoring tool and in decision making.

Evaluation of concurrent analysis of cerebrospinal fluid samples collected from the cerebellomedullary cistern and lumbar subarachnoid space for the diagnosis of steroid-responsive meningitis arteritis in dogs

OBJECTIVE

To evaluate whether concurrent analysis of CSF samples from 2 collection sites (cerebellomedullary cistern [CMC] and lumbar subarachnoid space [LSS]) versus only 1 site could improve the diagnostic sensitivity of CSF analysis for dogs with suspected steroid-responsive meningitis arteritis (SRMA).

ANIMALS

111 client-owned dogs with SRMA diagnosed at 3 veterinary referral hospitals between 2011 and 2017.

PROCEDURES

Only dogs with CSF collected from both sites (CMC and LSS) and with no previous history of corticosteroid administration were included. Medical record data and logistic regression were used to identify factors associated with having a total nucleated cell concentration (TNCC) within the reference interval in a CSF sample from 1 collection site.

RESULTS

The TNCC was within the reference interval (TNCC < 5 cells/μL) in the CSF sample from 1 collection site for 8 of 111 (7%) dogs and was only slightly high (TNCC, 5 to 9 cells/μL) in the sample from 1 or both sites for 10 (11%) other dogs. For each of these 18 dogs, results for samples from 1 site were consistent with SRMA. The proportion of CSF samples that had a TNCC within the reference interval was comparable between sites. As age increased, so did the risk of having an unremarkable TNCC in the CSF sample from 1 site, albeit only slightly (OR, 1.08; 95% confidence interval, 1.01 to 1.16).

CONCLUSIONS AND CLINICAL RELEVANCE

CSF samples from both the CMC and LSS should be analyzed when evaluating dogs with suspected SRMA to improve the chance of detecting a high TNCC.

Diagnosis and long-term outcome in dogs with acute onset intracranial signs

OBJECTIVES

To investigate dogs with acute onset of intracranial signs suspected of stroke by primary veterinary clinicians, and establish possible differential diagnoses and long-term outcome. In addition, serum C-reactive protein and plasma cytokines were investigated as potential biomarkers of disease.

MATERIALS AND METHODS

All cases were evaluated by neurologic examination, routine haematology and biochemistry and measurement of serum C-reactive protein, plasma cytokine concentrations (interleukin-2, -6, -8, -10, tumour necrosis factor) and low-field MRI.

RESULTS

Primary veterinarians contacted the investigators with 85 suspected stroke cases. Only 20 met the inclusion criteria. Of these, two were diagnosed with ischaemic stroke. Other causes were idiopathic vestibular syndrome (n=6), brain tumour (n=5) and inflammatory brain disease (n=2); in five cases a precise diagnosis could not be determined. Median survival times were: brain tumour, 3 days, idiopathic vestibular syndrome, 315 days, ischaemic stroke, 365 days and inflammatory central nervous system (CNS) disease, 468 days. The median plasma concentrations of interleukin-2, -6, -8, -10 or tumour necrosis factor were not significantly increased in any of the diagnosis groups compared to healthy controls. Serum C-reactive protein was higher in dogs with brain tumours and inflammatory brain disease but not above the upper bound of the reference interval.

CLINICAL SIGNIFICANCE

Dogs that present with acute onset intracranial disease may have ischaemic stroke but are more likely to have other causes. Many dogs with such acute onset of neurological dysfunction (brain tumours excluded) may recover within a couple of weeks despite their initial severe clinical appearance.

Immune-Mediated Central Nervous System Disease-Current Knowledge and Recommendations

Immune-mediated inflammation is responsible for about 25% of central nervous system disease in dogs. The disease can affect all ages and breeds, but young to middle-aged small breed dogs are over-represented for most forms. Diagnosis consists of advanced imaging (MRI), cerebrospinal fluid analysis, and infectious disease testing, but biopsy is required for definitive diagnosis and classification of the disease into one of the many subtypes. Treatment consists of immunosuppressive medication with the goal being to control and/or improve clinical signs. Current literature shows that prognosis is variable.

Clinical utility of currently available biomarkers in inflammatory enteropathies of dogs

Chronic inflammatory enteropathies (CIE) in dogs are a group of disorders that are characterized by chronic persistent or recurrent signs of gastrointestinal disease and histologic evidence of mucosal inflammation. These CIEs are classified as either food-responsive, antibiotic-responsive, or immunosuppressant-responsive enteropathy. Patients not clinically responding to immunomodulatory treatment are grouped as nonresponsive enteropathy and dogs with intestinal protein loss as protein-losing enteropathy. Disease-independent clinical scoring systems were established in dogs for assessment of clinical disease severity and patient monitoring during treatment. Histopathologic and routine clinicopathologic findings are usually not able to distinguish the subgroups of CIE. Treatment trials are often lengthy and further diagnostic tests are usually at least minimally invasive. Biomarkers that can aid in defining the presence of disease, site of origin, severity of the disease process, response to treatment, or a combination of these would be clinically useful in dogs with CIE. This article summarizes the following biomarkers that have been evaluated in dogs with CIE during the last decade, and critically evaluates their potential clinical utility in dogs with CIE: functional biomarkers (cobalamin, methylmalonic acid, folate, α1 -proteinase inhibitor, immunoglobulin A), biochemical biomarkers (C-reactive protein, perinuclear anti-neutrophilic cytoplasmic antibodies, 3-bromotyrosine, N-methylhistamine, calprotectin, S100A12, soluble receptor of advanced glycation end products, cytokines and chemokines, alkaline phosphatase), microbiomic biomarkers (microbiome changes, dysbiosis index), metabolomic biomarkers (serum metabolome), genetic biomarkers (genomic markers, gene expression changes), and cellular biomarkers (regulatory T cells). In addition, important performance criteria of diagnostic tests are briefly reviewed.

Inflammatory cytokine and C-reactive protein concentrations in dogs with systemic inflammatory response syndrome

OBJECTIVE

To evaluate C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α) kinetics in dogs with a systemic inflammatory response syndrome (SIRS) presented to an emergency service. We hypothesized serum CRP concentrations would increase and vary during hospitalization, and would correlate with plasma IL-6 and TNF-α concentrations, vary in magnitude according to the underlying disease, and predict survival.

DESIGN

Prospective, observational, clinical study.

SETTING

University emergency department.

ANIMALS

Sixty-nine dogs with SIRS weighing over 5 kg who could tolerate the blood sampling.

INTERVENTIONS

Serum and plasma were collected (and stored at -80°C) at presentation (T0), after 6 (T6), 12 (T12), 24 (T24), and 72 (T72) hours, and at a follow-up visit at least 1 month after discharge (T1m). Underlying diseases were categorized as infection (I), neoplasia (N), trauma (T), gastric-dilation and volvulus (GDV), other gastrointestinal (GI), renal (R), and miscellaneous (M) disease.

MEASUREMENTS AND MAIN RESULTS

Serum CRP concentration was measured using a canine-specific immunoturbidimetric assay. Biologically active plasma IL-6 and TNF-α concentrations were assessed using bioassays. Forty-four dogs survived, 8 died, and 17 were euthanized. Nineteen dogs had follow-up visits. At T0, serum CRP concentration was above the reference interval in 73.1% (49/67), and was within the reference interval (0-141.9 nmol/L) throughout hospitalization in only 6% (4/67). Serum CRP concentrations were significantly higher (P < 0.0001) at T0 (882.9 ± 1082.9 nmol/L) and at all time points during hospitalization (P < 0.0001) compared to T1m, with highest concentrations observed at T24 (906. 7 ± 859.0 nmol/L). At T1m, serum CRP concentrations were within the reference interval (22.9 ± 42.9 nmol/L) in 95% (18/19) of dogs. Logarithmic concentrations of serum CRP and plasma IL-6 were significantly correlated (P < 0.001, r = 0.479). None of the measured cytokines were associated with disease category or outcome.

CONCLUSIONS

Serum CRP concentration is increased in dogs with SIRS, and decreases during treatment and hospitalization. Serum CRP, plasma IL-6, and plasma TNF-α concentrations cannot predict outcome in dogs with SIRS.

Serum Thymidine Kinase 1, Canine-C-Reactive Protein, Haptoglobin, and Vitamin D Concentrations in Dogs with Immune-Mediated Hemolytic Anemia, Thrombocytopenia, and Polyarthropathy

Background

Relapses of immune‐mediated hemolytic anemia (IMHA), thrombocytopenia (ITP), or polyarthropathy (IMPA) occur despite normal hematologic and cytologic parameters. Thymidine kinase 1 (TK1), canine C‐reactive protein (c‐CRP), haptoglobin (HPT), and 25‐Hydroxyvitamin‐D (25(OH)D) might be adjunct to current monitoring strategies.

Hypothesis/Objectives

Compare serum concentrations of TK1, c‐CRP, HPT, and 25(OH)D in dogs with well‐ and poorly controlled primary IMHA, ITP, or IMPA.

Animals

Thirty‐eight client‐owned dogs.

Methods

Prospective descriptive study. Dogs diagnosed with IMHA, ITP, or IMPA had serum biomarker concentrations measured commercially. Disease control was assessed by hematocrit/PCV and reticulocyte count, platelet count, and synovial fluid cytology for IMHA, ITP, and IMPA, respectively. Statistical analysis performed by Mann‐Whitney rank‐sum tests and receiver operating characteristic curves.

Results

TK1 and c‐CRP, but not HPT significantly decreased with well‐ versus poorly controlled IMHA (P = 0.047, P = 0.028, P = 0.37). C‐CRP, but not TK or HPT was significantly lower with well‐ versus poorly controlled IMPA (P = 0.05, P = 0.28, P = 0.84). Sensitivity and specificity of TK and c‐CRP (simultaneously) for detecting dogs with poorly controlled IMHA were 88 and 100%, respectively. Sensitivity and specificity of c‐CRP for detecting poorly controlled dogs with IMPA were 13 and 100%, respectively. 92% of dogs were vitamin D insufficient (<100 ng/mL) regardless of disease control.

Conclusions and Clinical Importance

Combining TK1 and c‐CRP might act markers of disease control in dogs with IMHA. Canine‐CRP cannot be recommended as an independent marker of disease control in IMPA. 25(OH)D insufficiency in immune‐mediated disorders might benefit from further study to determine if supplementation could improve therapeutic response or reduce disease risk.

Serum C-reactive protein concentrations in Nova Scotia Duck Tolling Retrievers with immune-mediated rheumatic disease

Nova Scotia Duck Tolling Retrievers (NSDTRs) are a dog breed often affected by immune-mediated rheumatic disease (IMRD), a disorder characterised by chronic stiffness and joint pain. Most, but not all, dogs with IMRD, have antinuclear antibodies (ANA), which are also commonly present in the autoimmune disease systemic lupus erythematosus (SLE). The clinical and diagnostic findings of IMRD indicate that it is an SLE-related disorder. C-reactive protein (CRP), an acute phase protein, is a quantitative marker of inflammation for many diseases and is used for diagnosing and monitoring systemic inflammation in both humans and dogs. However, in human SLE, CRP concentrations are often elevated but correlate poorly with disease activity; they can be low in individual patients with active disease. The aim of the study was to investigate CRP in a group of NSDTRs with the SLE-related disorder IMRD. The hypothesis was that CRP concentrations would be increased in dogs with IMRD compared to healthy dogs, but that the increase would be mild. Serum CRP concentrations were measured in 18 IMRD-affected NSDTRs and 19 healthy control NSDTRs using two different canine-specific CRP assays. Dogs with IMRD and ANA had higher CRP concentrations than the control dogs, but the concentrations were below the clinical decision limit for systemic inflammation for most of the IMRD dogs. These results indicate that CRP concentrations were increased in dogs with IMRD and ANA, but the increase was mild, similar to what has been observed in human SLE.

The Utility of Acute-Phase Proteins in the Assessment of Treatment Response in Dogs With Bacterial Pneumonia

Background

Acute‐phase proteins (APPs) are sensitive markers of inflammation, and serum C‐reactive protein (CRP) recently has been shown to be a useful diagnostic marker in dogs with bacterial pneumonia (BP). In humans with community‐acquired pneumonia, APPs also have great utility as follow‐up markers aiding in the assessment of treatment response.

Objectives

The aim of our study was to investigate the applicability of APPs as markers of treatment response in dogs with BP.

Animals

Nineteen dogs diagnosed with BP and 64 healthy dogs.

Methods

The study was conducted as a prospective longitudinal observational study. Serum CRP, serum amyloid A (SAA), and haptoglobin concentrations were followed during a natural course of BP. Normalization of serum CRP was used to guide the duration of antibiotic treatment (treatment was stopped 5–7 days after CRP normalized) in 8 of 17 dogs surviving to discharge; 9 of 17 dogs were treated according to conventional recommendations.

Results

All measured APPs initially were significantly increased, but the magnitude of increase was not correlated to disease severity. C‐reactive protein and SAA concentrations decreased rapidly after initiation of antimicrobial treatment. When normalization of serum CRP was used to guide the duration of antibiotic treatment, treatment duration was significantly (P = .015) decreased without increasing the number of relapses.

Conclusions and Clinical Importance

Serum CRP and SAA reflected the recovery process well and therefore may be used as markers of treatment response. According to the results, the normalization of serum CRP may be used to guide the duration of antibiotic treatment in dogs with BP.

Relapses in dogs with steroid-responsive meningitis-arteritis

OBJECTIVES

To describe relapse rates in steroid-responsive meningitis-arteritis and to describe clinical and laboratory parameters in dogs with and without relapses.

METHODS

Seventy-four dogs with steroid-responsive meningitis-arteritis were retrospectively identified and assigned to one of three groups: (1) without relapse; (2) at least one relapse and (3) unknown relapse status. The following parameters are reported for the first two groups: sex, age, breed, body weight, nucleated cell count, total protein concentration and percentage of neutrophils on initial cerebrospinal fluid analysis, immunoglobulin A in serum and initial cerebrospinal fluid analysis, nucleated cell count on cerebrospinal fluid analysis at 3-month re-evaluation, C-reactive protein in serum and initial cerebrospinal fluid analysis and at 3-month re-evaluation.

RESULTS

Relapses occurred in 32 · 4% of dogs (one relapse: 62 · 5%; two relapses: 25 · 0%; three relapses: 8 · 3%; four relapses: 4 · 2%), 55 · 4% were relapse-free and in 12 · 2% the relapse status was unknown. C-reactive protein in serum and cerebrospinal fluid on 3-month re-evaluation was normal in 80% and 75% of dogs with relapses, respectively. In dogs without relapse, C-reactive protein in serum and cerebrospinal fluid on 3-month re-evaluation was normal in 100% and 90% of dogs, respectively.

CLINICAL SIGNIFICANCE

Relapses are frequent but no reliable predictive indicator has emerged in this study. Nevertheless, elevated C-reactive protein in serum warrants continuing therapy; normal C-reactive protein in serum does not exclude future relapse.

Acute Phase Proteins in Cerebrospinal Fluid from Dogs with Naturally-Occurring Spinal Cord Injury

Spinal cord injury (SCI) affects thousands of people each year and there are no treatments that dramatically improve clinical outcome. Canine intervertebral disc herniation is a naturally-occurring SCI that has similarities to human injury and can be used as a translational model for evaluating therapeutic interventions. Here, we characterized cerebrospinal fluid (CSF) acute phase proteins (APPs) that have altered expression across a spectrum of neurological disorders, using this canine model system. The concentrations of C-reactive protein (CRP), haptoglobin (Hp), alpha-1-glycoprotein, and serum amyloid A were determined in the CSF of 42 acutely injured dogs, compared with 21 healthy control dogs. Concentrations of APPs also were examined with respect to initial injury severity and motor outcome 42 d post-injury. Hp concentration was significantly higher (p<0.0001) in the CSF of affected dogs, compared with healthy control dogs. Additionally, the concentrations of CRP and Hp were significantly (p=0.0001 and p=0.0079, respectively) and positively associated with CSF total protein concentration. The concentrations of CRP and Hp were significantly higher (p=0.0071 and p=0.0197, respectively) in dogs with severe injury, compared with those with mild-to-moderate SCI, but there was no significant correlation between assessed CSF APP concentrations and 42 d motor outcome. This study demonstrated that CSF APPs were dysregulated in dogs with naturally-occurring SCI and could be used as markers for SCI severity. As Hp was increased following severe SCI and is neuroprotective across a number of model systems, it may represent a viable therapeutic target.

Validation of a commercially available automated canine-specific immunoturbidimetric method for measuring canine C-reactive protein

BACKGROUND

Measurement of C-reactive protein (CRP) is used for diagnosing and monitoring systemic inflammatory disease in canine patients. An automated human immunoturbidimetric assay has been validated for measuring canine CRP, but cross-reactivity with canine CRP is unpredictable.

OBJECTIVE

The purpose of the study was to validate a new automated canine-specific immunoturbidimetric CRP method (Gentian cCRP).

METHODS

Studies of imprecision, accuracy, prozone effect, interference, limit of quantification, and stability under different storage conditions were performed. The new method was compared with a human CRP assay previously validated for canine CRP determination. Samples from 40 healthy dogs were analyzed to establish a reference interval.

RESULTS

Total imprecision was < 2.4% for 4 tested serum pools analyzed twice daily over 10 days. The method was linear under dilution, and no prozone effect was detected at a concentration of 1200 mg/L. Recovery after spiking serum with purified canine CRP at 2 different concentrations was 123% and 116%, respectively. No interference from hemoglobin or triglycerides (10 g/L) was detected. CRP was stable for 14 days at 4°C and 22°C. In the method comparison study, there was good agreement between the validated human CRP assay and the new canine-specific assay. Healthy dogs had CRP concentrations that were less than the limit of quantification of the Gentian cCRP method (6.8 mg/L).

CONCLUSIONS

The new canine-specific immunoturbidimetric CRP assay is a reliable and rapid method for measuring canine CRP, suitable for clinical use due to the option for an automated assay.

Serum biomarkers of clinical and cytologic response in dogs with idiopathic immune-mediated polyarthropathy

Background

Immune‐mediated polyarthopathy (IMPA) is common in dogs, and is monitored by serial arthrocenteses.

Hypothesis/Objectives

Plasma C‐reactive protein (CRP), interleukin‐6 (IL‐6), and CXCL8 (interleukin‐8) would serve as noninvasive markers of joint inflammation in IMPA.

Animals

Nine client‐owned dogs with idiopathic IMPA; 6 healthy controls.

Methods

Prospective study. Plasma CRP, IL‐6, and CXCL8 were measured by ELISA at baseline, 2, and 4 weeks during treatment with prednisone at 50 mg/m²/day. Arthrocenteses, the canine brief pain inventory (CBPI), and accelerometry collars were used to assess joint inflammation, lameness, and mobility at all 3 time points.

Results

C‐reactive protein concentrations were higher in IMPA dogs (median 91.1 μg/mL, range 76.7–195.0) compared with controls (median <6.3 μg/mL, <6.3–13.7; P = .0035), and were significantly lower at week 2 (10.6 μg/mL, <6.3–48.8) and week 4 (<6.3 μg/mL, <6.3–24.4; P < .001).

C‐reactive protein was correlated with median CBPI scores (r = 0.68; P = .0004), joint cellularity (r = 0.49, P = .011), and mobility by accelerometry (r = −0.42, P = .048). Plasma IL‐6 concentrations were also higher in IMPA dogs (median 45.9 pg/mL), compared with controls (median <15.7 pg/mL; P = .0008). IL‐6 was lower in IMPA dogs by week 4 (<15.7 pg/mL; P = .0099), and was modestly correlated with CBPI scores (r = 0.47, P = .023). CXCL8 did not differ significantly between IMPA and healthy dogs.

Conclusions

Plasma CRP and IL‐6 might be useful surrogate markers of synovial inflammation and disease activity in dogs with IMPA.

Interleukin-6, vascular endothelial growth factor and transforming growth factor beta 1 in canine steroid responsive meningitis-arteritis

Background

Steroid Responsive Meningitis-Arteritis (SRMA) is a common cause of inflammation of the canine central nervous system (CNS). To investigate if transforming growth factor beta 1 (TGF-β₁), interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) are involved in the production of excessive immunoglobulin A (IgA), the induction of acute phase proteins and in the development of a systemic necrotizing vasculitis, characteristic of SRMA, these three signalling proteins were evaluated.

Results

Cerebrospinal fluid (CSF) and serum samples of dogs during the acute phase of SRMA (SRMA) were tested for IL-6, VEGF and TGF- β₁. Results were compared to those of dogs affected with SRMA during treatment (SRMA Th) and during relapse (SRMA R), to dogs with other meningoencephalomyelitides (ME), with miscellaneous non-inflammatory diseases of the CNS (CNS-Mix), with idiopathic epilepsy (IE), with systemic inflammatory diseases (Syst. Infl.) and with healthy dogs (Healthy). Concentrations of IL-6 and VEGF in CSF were significantly elevated in the SRMA group compared to the other disease categories (p < 0.05). The CSF concentrations of TGF-β₁ were increased in SRMA group, but statistically significant differences were found only in comparison with Healthy and CNS-Mix groups. No differences were detected in the serum concentrations of TGF-β₁ between the different groups. In untreated SRMA patients, a positive correlation (r_Spear = 0.3549; P = 0.0337) between concentrations of TGF-β₁ and IgA concentration was found in CSF, while concentrations of IL-6 and VEGF in CSF positively correlated with the degree of pleocytosis (r_Spear = 0.8323; P < 0.0001 and r_Spear = 0.5711; P = 0.0166, respectively).

Conclusions

Our results suggest that these three signalling proteins are biomarkers of disease activity in SRMA. VEGF might play an important role in the development of a systemic arteritis. TGF-β₁ is considered to be involved in the excessive IgA production, while IL-6 in the pleocytosis. The combined intrathecal increase of TGF-β₁ and IL-6 detected in SRMA could possibly force CD4 progenitors to differentiate towards the newly described Th17 lymphocyte subset and enhance the autoimmune response.

Canine serum amyloid A (SAA) measured by automated latex agglutination turbidimetry is useful for routine sensitive and specific detection of systemic inflammation in a general clinical setting

Canine serum amyloid A (SAA) is a useful diagnostic marker of systemic inflammation. A latex agglutination turbidimetric immunoassay (LAT) was validated for automated measurements. The aim of the study was to evaluate the clinical applicability of SAA measured by the LAT. SAA was measured in 7 groups of dogs with and without systemic inflammation (n=247). Overlap performance was investigated. Diagnostic performance was compared to body temperature and leukocyte markers. Clinical decision limits for SAA were estimated. In dogs with neurological, neoplastic or gastrointestinal disorders (n=143), it was investigated whether a higher proportion of SAA positive dogs could be detected in cases of complications with risk of systemic inflammation. Significantly higher concentrations of SAA were measured in dogs with (range [48.75; 5,032 mg/l]), compared to dogs without systemic inflammation [0; 56.4 mg/l]. SAA was a more sensitive and specific marker of systemic inflammation (area under the receiver-operating characteristic curve (AUC) 1.00), compared to body temperature (0.6) and segmented neutrophils (best performing leukocyte marker, 0.84). A clinical decision limit of 56.4 mg/l was established giving close to perfect discrimination between dogs with and without systemic inflammation. Higher proportions of SAA-positive dogs were observed in dogs with neurological, neoplastic and gastrointestinal disorders with complications known to increase risk of systemic inflammation, compared to uncomplicated cases. The automated LAT makes SAA applicable as a relevant diagnostic marker of systemic inflammation in dogs for routine random-access real-time use in a general clinical setting.

Experimental Ehrlichia canis infection changes acute-phase proteins

Early diagnosis of canine ehrlichiosis favors prompt institution of treatment and improves the prognosis for the animal, since this disease causes mortality among dogs. Studies have shown that determining the concentration of acute-phase proteins (APPs) may contribute towards early detection of disease and aid in predicting the prognosis. This study aimed to evaluate the APP profile in dogs experimentally infected with Ehrlichia canis, at the start of the infection and after treatment. It also investigated whether any correlation between APP levels and the clinical and laboratory alterations over the course of the disease would be possible. The results obtained showed abnormal levels of all the APPs on the third day after infection (D3), with the highest levels being reached on D18, with the exception of ceruloplasmin and acid glycoprotein, which presented their peaks on D6 and D12 respectively. We concluded that assessment of APP levels could contribute towards establishing an early diagnosis of canine ehrlichiosis, particularly regarding acid glycoprotein and ceruloplasmin, since these proteins were detected at increased levels even before the onset of clinical and laboratory findings of the disease.

Fibrinolytic activity in cerebrospinal fluid of dogs with different neurological disorders

BACKGROUND

Fibrinolytic activity in cerebrospinal fluid (CSF) is activated in humans by different pathologic processes.

OBJECTIVES

To investigate fibrinolytic activity in the CSF of dogs with neurological disorders by measuring CSF D-dimer concentrations.

ANIMALS

One hundred and sixty-nine dogs with neurological disorders, 7 dogs with systemic inflammatory diseases without central nervous system involvement (SID), and 7 healthy Beagles were included in the study. Dogs with neurological disorders included 11 with steroid-responsive meningitis-arteritis (SRMA), 37 with other inflammatory neurological diseases (INF), 38 with neoplasia affecting the central nervous system (NEO), 28 with spinal compressive disorders (SCC), 15 with idiopathic epilepsy (IE), and 40 with noninflammatory neurological disorders (NON-INF).

METHODS

Prospective observational study. D-dimers and C-reactive protein (CRP) were simultaneously measured in paired CSF and blood samples.

RESULTS

D-dimers and CRP were detected in 79/183 (43%) and in 182/183 (99.5%) CSF samples, respectively. All dogs with IE, SID, and controls had undetectable concentrations of D-dimers in the CSF. CSF D-dimer concentrations were significantly (P < .001) higher in dogs with SRMA than in dogs with other diseases and controls. CSF CRP concentration in dogs with SRMA was significantly (P < .001) higher than in dogs of other groups and controls, except for the SID group. No correlation was found between blood and CSF D-dimer concentrations.

CONCLUSIONS AND CLINICAL IMPORTANCE

Intrathecal fibrinolytic activity seems to be activated in some canine neurological disorders, and it is high in severe meningeal inflammatory diseases. CSF D-dimer concentrations may be considered a diagnostic marker for SRMA.

Evaluation of an automated assay based on monoclonal anti-human serum amyloid A (SAA) antibodies for measurement of canine, feline, and equine SAA

Major acute phase proteins (APPs) have proven diagnostically useful in dogs, cats and horses with routine use facilitated by commercially available automated heterologous assays. An automated assay applicable across all three species would highly facilitate further dissemination of routine use, and the aim of this study was to validate an automated latex agglutination turbidimetric immunoassay based on monoclonal anti-human serum amyloid A (SAA) antibodies for measurement of canine, feline and equine SAA. Serum samples from 60 dogs, 40 cats and 40 horses were included. Intra- and inter-assay imprecision, linearity and detection limit (DL) were determined to assess analytical performance. To assess clinical performance, equine and feline SAA measurements were compared with parallel measurements using a previously validated automated SAA assay in a method comparison setting, and by assessing overlap performance of canine SAA in healthy dogs and diseased dogs with and without systemic inflammation. Intra- and inter-assay CVs ranged between 1.9-4.6% and between 3.0-14.5%, respectively. Acceptable linearity within a clinically relevant range of SAA concentrations was observed for all three species. The DL was 1.06 mg/L. Method comparison revealed acceptable agreement of the two assays measuring feline and equine SAA, and the overlap performance of canine SAA was acceptable. The tested assay measured SAA in canine, feline and equine serum with analytical and overlap performance acceptable for clinical purposes so improving practical aspects of clinical APP application. The monoclonal nature of the antibodies suggests strong, long-term inter-batch performance stability.

The immunopathology of sepsis: pathogen recognition, systemic inflammation, the compensatory anti-inflammatory response, and regulatory T cells

Sepsis, the systemic inflammatory response to infection, represents the major cause of death in critically ill veterinary patients. Whereas important advances in our understanding of the pathophysiology of this syndrome have been made, much remains to be elucidated. There is general agreement on the key interaction between pathogen-associated molecular patterns and cells of the innate immune system, and the amplification of the host response generated by pro-inflammatory cytokines. More recently, the concept of immunoparalysis in sepsis has also been advanced, together with an increasing recognition of the interplay between regulatory T cells and the innate immune response. However, the heterogeneous nature of this syndrome and the difficulty of modeling it in vitro or in vivo has both frustrated the advancement of new therapies and emphasized the continuing importance of patient-based clinical research in this area of human and veterinary medicine.

Acute phase proteins in animals

Acute phase proteins (APP) were first identified in the early 1900s as early reactants to infectious disease. They are now understood to be an integral part of the acute phase response (APR) which is the cornerstone of innate immunity. APP have been shown to be valuable biomarkers as increases can occur with inflammation, infection, neoplasia, stress, and trauma. All animals--from fish to mammals--have demonstrable APP, but the type of major APP differs by species. While the primary application of these proteins in a clinical setting is prognostication, studies in animals have demonstrated relevance to diagnosis and detection and monitoring for subclinical disease. APP have been well documented in laboratory, companion, and large animals. With the advent of standardized and automated assays, these biomarkers are available for use in all fields of veterinary medicine as well as basic and clinical research.

Acute phase protein concentrations in dogs with nasal disease

The concentrations of C-reactive protein (CRP), serum amyloid A, haptoglobin (Hp) and α(1)-acid glycoprotein were measured in dogs with clinical signs of nasal disease and compared with those of healthy dogs in order to determine the expression of these proteins in cases of canine nasal disease. A significant difference (P<0.001) between the symptomatic group and the control group was found for both CRP and Hp. Among the animals with nasal disease, a significant intergroup difference (P<0.05) was found in the expression of Hp between dogs with aspergillosis and those with chronic rhinitis.