Prospective pilot study to detect dogs with non food-induced canine atopic dermatitis using Fourier transform infrared spectroscopy

A new strategy for canine visceral leishmaniasis diagnosis based on FTIR spectroscopy and machine learning

Visceral leishmaniasis is a neglected disease caused by protozoan parasites of the genus Leishmania. The successful control of the disease depends on its accurate and early diagnosis, which is usually made by combining clinical symptoms with laboratory tests such as serological, parasitological, and molecular tests. However, early diagnosis based on serological tests may exhibit low accuracy due to lack of specificity caused by cross-reactivities with other pathogens, and sensitivity issues related, among other reasons, to disease stage, leading to misdiagnosis. In this study was investigated the use of mid-infrared spectroscopy and multivariate analysis to perform a fast, accurate, and easy canine visceral leishmaniasis diagnosis. Canine blood sera of 20 noninfected, 20 Leishmania infantum, and eight Trypanosoma evansi infected dogs were studied. The data demonstrate that principal component analysis with machine learning algorithms achieved an overall accuracy above 85% in the diagnosis.

Attenuated total reflection Fourier transform infrared as a primary screening method for cancer in canine serum

Cancer is a major cause of death in dogs worldwide, and the incidence of cancer in dogs is increasing. The attenuated total reflection Fourier transform infrared spectroscopic (ATR-FTIR) technique is a powerful tool for the diagnosis of several diseases. This method enables samples to be examined directly without pre-preparation. In this study, we evaluated the diagnostic value of ATR-FTIR for the detection of cancer in dogs. Cancer-bearing dogs (n = 30) diagnosed by pathologists and clinically healthy dogs (n = 40) were enrolled in this study. Peripheral blood was collected for clinicopathological diagnosis. ATR-FTIR spectra were acquired, and principal component analysis was performed on the full wave number spectra (4,000–650 cm⁻¹). The leave-one-out cross validation technique and partial least squares regression analysis were used to predict normal and cancer spectra. Red blood cell counts, hemoglobin levels and white blood cell counts were significantly lower in cancer-bearing dogs than in clinically healthy dogs (p < 0.01, p < 0.01 and p = 0.03, respectively). ATR-FTIR spectra showed significant differences between the clinically healthy and cancer-bearing groups. This finding demonstrates that ATR-FTIR can be applied as a screening technique to distinguish between cancer-bearing dogs and healthy dogs.

Reliability of different sets of criteria in diagnosing canine atopic dermatitis applied to a population of 250 dogs seen in a veterinary teaching hospital

BACKGROUND

Different sets of criteria are available in veterinary dermatology for the diagnosis of canine atopic dermatitis (cAD); there are limited data to assess their reliability.

HYPOTHESIS/OBJECTIVES

The aim of this study was to assess the discriminative and predictive ability of four sets in diagnosing cAD in a population of dogs with different skin diseases.

ANIMALS

Two hundred and fifty dogs examined in the dermatology unit of a veterinary teaching hospital.

METHODS AND MATERIALS

Dogs were diagnosed with cAD, flea infestation (FI), flea bite hypersensitivity (FBH), sarcoptic mange (SM) and other skin diseases (OD). FI, FBH and SM were pooled in one group of dermatoses mimicking cAD (MD). All nonatopic dogs were grouped as a "global population" (GP). Four criteria sets were applied to all dogs. For each set of criteria, sensitivity, specificity, positive and negative predictive values (PPV, NPV), likelihood ratios (LR) and diagnostic odds ratio (DOR) were calculated.

RESULTS

When applied to the GP, sensitivities ranged from 54 to 83%, specificities from 68 to 75% and PPVs from 35 to 43%. NPVs ranged from 87 to 94%. LRs and DORs were poor. When applied to MD, sensitivities remained unchanged, specificities and PPV were mildly higher, whereas NPVs were mildly lower and LRs and DORs were comparable.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study showed that each set of criteria had a low diagnostic reliability when used alone. The use of more discriminant criteria integrated into a thorough clinical approach excluding MDs should be considered.

A pilot study on fingerprinting Leishmania species from the Old World using Fourier transform infrared spectroscopy

Leishmania species are protozoan parasites and the causative agents of leishmaniasis, a vector borne disease that imposes a large health burden on individuals living mainly in tropical and subtropical regions. Different Leishmania species are responsible for the distinct clinical patterns, such as cutaneous, mucocutaneous, and visceral leishmaniasis, with the latter being potentially fatal if left untreated. For this reason, it is important to perform correct species identification and differentiation. Fourier transform infrared spectroscopy (FTIR) is an analytical spectroscopic technique increasingly being used as a potential tool for identification of microorganisms for diagnostic purposes. By employing mid-infrared (MIR) spectral data, it is not only possible to assess the chemical structures but also to achieve differentiation supported by multivariate statistic analysis. This work comprises a pilot study on differentiation of Leishmania species of the Old World (L. major, L. tropica, L. infantum, and L. donovani) as well as hybrids of distinct species by using vibrational spectroscopic fingerprints. Films of intact Leishmania parasites and their deoxyribonucleic acid (DNA) were characterized comparatively with respect to their biochemical nature and MIR spectral patterns. The strains’ hyperspectral datasets were multivariately examined by means of variance-based principal components analysis (PCA) and distance-based hierarchical cluster analysis (HCA). With the implementation of MIR spectral datasets we show that a phenotypic differentiation of Leishmania at species and intra-species level is feasible. Thus, FTIR spectroscopy can be further exploited for building up spectral databases of Leishmania parasites in view of high-throughput analysis of clinical specimens.

Graphical abstract