Porcine Forebrain Vacuolization Associated with Wasting in Pigs : A Novel Pathological Outcome Associated with Vitamin-Mineral Deficiency?

The term wasting is a clinical name describing a physical condition characterized by growth retardation, usually of multifactorial origin. The present study describes an apparently new condition of pigs characterized clinically by wasting and pathologically by vacuolization of the brain. During 2016-2018, animals from eight farms were weaned in good body condition, and after 1-2 weeks, they started losing weight. To investigate potential causes of this condition, apparently sick and healthy pigs from each herd of eight affected farms were studied by means of histopathology, transmission electron microscopy and detection of usual infectious agents. Histopathologically, the most consistent lesion was neuropil vacuolization of the prosencephalon, mainly located in the thalamic nuclei and in the transition between the white and grey matter of the neocortex. Electron microscopy of some of these sick animals showed preserved axons, with dilated myelin sheaths (interpreted as edema of myelin sheath). The literature suggests this lesion type is linked to congenital or metabolic (toxic/deficiency) scenarios. The present case was probably a vitamin/mineral deficiency since supplementation with nutritional complexes solved the problem. The term wasting refers to a clinical sign used to describe a physical condition characterized by growth retardation, usually of multifactorial origin. The objective of the present study was to describe for the first time a pathological process characterized by forebrain neuropil vacuolization in pigs showing wasting without conspicuous neurological signs. To characterize the lesions pathologically, affected and non-affected pigs from eight of these farms were investigated. Histologically, the most consistent lesion was neuropil vacuolization of the prosencephalon, mainly located in the thalamic nuclei and in the transition between the white and grey matter of the neocortex (40/56 in sick and 4/30 in healthy pigs). In the most severe cases, the vacuolation also involved the midbrain, cerebellar nuclei and, to a lesser extent, the medulla oblongata. Vacuolization of the forebrain was associated with pigs experiencing marked emaciation and growth retardation. Although the specific cause of the present case remained unknown, the preventive use of multivitamin and mineral complexes in drinking water ameliorated the condition, strongly suggesting a metabolic origin of the observed condition

Efficacy of parenteral vaccination against tuberculosis with heat-inactivated Mycobacterium bovis in experimentally challenged goats

Tuberculosis (TB) in animals is a re-emerging disease with a wide range of hosts that causes large economic losses in livestock. Goats are particularly susceptible to TB and, in endemic areas, vaccination may be a valuable measure to control the disease. The main aim of this study was to evaluate the efficacy of parenteral vaccination of goats with a heat-inactivated Mycobacterium bovis (HIMB) vaccine, and compare it to M. bovis Bacille Calm-ette-Guérin (BCG) vaccine. Twenty-four goat kids were divided in 3 groups as following: HIMB vaccinated group (n = 8), BCG vaccinated group (n = 8) and unvaccinated group (n = 8). Afterwards, goats were experimentally challenged with Mycobacterium caprae by the endobronchial route. Antigen specific interferon-γ release assays and serology were performed after vaccination and challenge. Pathological and bacteriological parameters were evaluated after necropsy at 9 weeks post-challenge (p.c.). HIMB vaccine showed similar levels of protection to BCG in terms of volume reduction of thoracic TB lesions, presence of extra-pulmonary lesions, as well as a slight reduction of bacterial load in pulmonary lymph nodes. Moreover, HIMB vaccine did not induce interferences on the interferon-γ release assay based on reagents previously developed to differentiate infected from BCG vaccinated individuals. The results indicate that HIMB is a suitable vaccine candidate for further larger-scale trials under field conditions in goats

Efficacy of parenteral vaccination against tuberculosis with heat-inactivated <i>Mycobacterium bovis</i> in experimentally challenged goats

<div><p>Tuberculosis (TB) in animals is a re-emerging disease with a wide range of hosts that causes large economic losses in livestock. Goats are particularly susceptible to TB and, in endemic areas, vaccination may be a valuable measure to control the disease. The main aim of this study was to evaluate the efficacy of parenteral vaccination of goats with a heat-inactivated <i>Mycobacterium bovis</i> (HIMB) vaccine, and compare it to M. <i>bovis</i> Bacille Calmette–Guérin (BCG) vaccine. Twenty-four goat kids were divided in 3 groups as following: HIMB vaccinated group (n = 8), BCG vaccinated group (n = 8) and unvaccinated group (n = 8). Afterwards, goats were experimentally challenged with <i>Mycobacterium caprae</i> by the endobronchial route. Antigen specific interferon-γ release assays and serology were performed after vaccination and challenge. Pathological and bacteriological parameters were evaluated after necropsy at 9 weeks post-challenge (p.c.). HIMB vaccine showed similar levels of protection to BCG in terms of volume reduction of thoracic TB lesions, presence of extra-pulmonary lesions, as well as a slight reduction of bacterial load in pulmonary lymph nodes. Moreover, HIMB vaccine did not induce interferences on the interferon-γ release assay based on reagents previously developed to differentiate infected from BCG vaccinated individuals. The results indicate that HIMB is a suitable vaccine candidate for further larger-scale trials under field conditions in goats.</p></div

Number of positive goats to each IFN-γ release assay.

<p>Number of positive goats to each IFN-γ release assay.</p

Quantitative pathological results.

<p>(<b>A-C</b>) Individual volumes of TB lesions expressed in cm³. (<b>D-F</b>) Individual ratios between volumes expressed in %. (<b>A</b>) Total volume of lesions in pulmonary lymph nodes (LN). Groups: Control (n = 8), BCG (n = 8) and HIMB (n = 7). (<b>B</b>) Total volume of lung lesions. (<b>C</b>) Total volume of mineralized lesions in lungs. (<b>D</b>) Ratio of total volume of lung lesions / volume of the whole lung. (<b>E</b>) Ratio of total volume of lung mineralization / total volume of lung lesions. (<b>F</b>) Ratio of total volume of lung mineralization / volume of the whole lung. Groups (<b>B-F</b>): Control (n = 6), BCG (n = 7) and HIMB (n = 7). Horizontal lines represent median values. · <i>P</i> < 0.1, * <i>P</i> < 0.05, ** <i>P</i> < 0.01, *** <i>P</i> < 0.001, Kruskal-Wallis test with the <i>post hoc</i> Wilcoxon rank sum test with Bonferroni correction.</p

Number of animals with clinical signs after <i>M</i>. <i>caprae</i> challenge.

<p>Number of animals with clinical signs after <i>M</i>. <i>caprae</i> challenge.</p