Review/Oorsig Volume 22, Issue 05 - Page 6

Oorsig/Review Collection of microbiology specimens and spleen smears Scan to view video http://bit.ly/2A3Vl8v Thyroid gland examination Scan to view video http://bit.ly/2Pt0mlx The gland is located on either side of the larynx linked by a thin isthmus. In general terms if the gland is easy to locate on gross examination it is probably enlarged. Weigh the gland and collect for histopathology. Ensure slice through capsule for adequate formalin fixation. Figure 9: Visceral pleural fibrosis.png interstitial pneumonia is indicative of viral or toxic causes of abortion. Calculate the thyroid weight to body weight ratio. • Thyroid weight (in grams) ÷ Body weight ratio (in grams) – Express as percentage (target ratio <0.03%). Figure 10: Miliary hepatic necrosis (IBR abortion) Enlarged thyroid glands (hyperplastic goiter) in late stage abortions, stillbirths, perinatal deaths or weak neonates in cattle, sheep and goats, should alert the investigator to possible underlying micronutrient deficiencies / imbalances (iodine, selenium, copper, manganese, iron, chromium) especially when accompanied by cardiomyopathy, ingestion of goitrogenic plants / anti-thyroid compounds by the dam (in particular prussic acid containing plants), in-utero exposure to certain toxic agents (mycotoxins) or ingestion of endocrine disrupting agents by the dam. Internal organ examination Heart: open the pericardium to examine for evidence of pericarditis, which is an indicator lesion for bacterial abortion. Observe the myocardium for any evidence of myocarditis, myocardial degeneration or mineralization (see above). Evaluate the ventricular walls for any evidence of cardiomyopathy. Lungs: visceral pleural fibrosis is a normal finding in ruminant fetuses. Lesions of bronchopneumonia and pleuropneumonia are indicative of bacterial causes of abortion, while 6 Liver: multifocal hepatic necrosis is an important fetal lesion indicative of various infectious causes including viral (bovine herpesvirus, Rift Valley fever, Wesselsbron), protozoal (toxoplasmosis) and bacterial (Listeria, Salmonella). IBR virus (BHV-1) is an important cause of abortion in cattle. Abortion generally follows the respiratory form of the disease or use of modified live IBR vaccine in pregnant previously unvaccinated animals, although over the past decade an apparent increase of post-vaccinal abortion episodes have been reported in well vaccinated animals given a booster vaccine during pregnancy. It is important to remember that BHV-1 infects ovarian tissue, including corpora lutea inducing necrotizing oophoritis and return to estrus. The liver also provides a useful organ for evaluation of circulatory failure in the fetus as hepatic cyanotic induration is a lesion commonly associated with fetal heart failure. Intestine: in the bovine fetus, necrotizing colitis is a pathognomonic lesion for Listeria abortion.