Bacillus anthracis as a cause of bovine abortion - a necropsy case requiring special biosafety measures.

INTRODUCTION: In spring 2017, the first case of bovine anthrax in 20 years in Switzerland occurred in the canton of Jura. Carcasses of anthrax-deceased animals should not be opened due to the formation of highly resistant spores bearing the risk of environmental contamination and aerosolization. Nevertheless, in the course of this local outbreak, one sick cow from the affected farm, whose blood repeatedly tested negative for Bacillus anthracis, was necropsied after euthanasia under special biosafety precautions at the Institute of Animal Pathology, Vetsuisse-Faculty Bern. Necropsy revealed ventral edema, fetal death, necro-hemorrhagic placentitis and necrotizing iliac lymphadenitis. Bacillus anthracis was isolated only from placenta and altered lymph node. The biosafety measures taken during and after necropsy prevented a contamination of the necropsy environment, which was proven with bacteriological swabs. This case shows that anthrax may elicit unspecific symptoms mimicking other diseases, and veterinarians must be aware of these non-septicemic cases.

Clinicopathological Phenotype of Autosomal Recessive Cholesterol Deficiency in Holstein Cattle.

BACKGROUND: Cholesterol deficiency (CD), a newly identified autosomal recessive genetic defect in Holstein cattle, is associated with clinical signs of diarrhea, failure to thrive, and hypocholesterolemia. HYPOTHESIS/OBJECTIVES: The objective is to describe the clinicopathological phenotype of affected Holstein cattle homozygous for the causative apolipoprotein B gene (APOB) mutation. ANIMALS: Six Holstein cattle, 5 calves with a clinical history of chronic diarrhea, and 1 heifer with erosions in the buccal cavity and neurologic symptoms were admitted to the Clinic for Ruminants. METHODS: This case review included a full clinical examination, a complete blood count, blood chemistry, and measurements of cholesterol and triglycerides. The animals were euthanized and necropsied. A PCR-based direct gene test was applied to determine the APOB genotype. RESULTS: All 6 animals were inbred, could be traced back to the sire Maughlin Storm, and were confirmed homozygous for the APOB mutation. The clinical phenotype included poor development, underweight, and intermittent diarrhea in the calves, and neurologic signs in the heifer included hypermetria and pacing. Hypocholesterolemia and low triglycerides concentrations were present in all animals. The pathological phenotype of all animals was steatorrhea with enterocytes of the small intestine containing intracytoplasmic lipid vacuoles. The peripheral nervous system of the heifer displayed degenerative changes. CONCLUSIONS AND CLINICAL IMPORTANCE: Suspicion of CD in Holstein cattle is based on the presence of chronic diarrhea with no evidence of primary infections. Confirmation of the associated APOB gene mutation is needed. Additionally, the heifer demonstrated primarily signs of neurologic disease providing an unexpected phenotype of CD.

A transposable element insertion in APOB causes cholesterol deficiency in Holstein cattle.

Cholesterol deficiency, a new autosomal recessive inherited genetic defect in Holstein cattle, has been recently reported to have an influence on the rearing success of calves. The affected animals show unresponsive diarrhea accompanied by hypocholesterolemia and usually die within the first weeks or months of life. Here, we show that whole genome sequencing combined with the knowledge about the pedigree and inbreeding status of a livestock population facilitates the identification of the causative mutation. We resequenced the entire genomes of an affected calf and a healthy partially inbred male carrying one copy of the critical 2.24-Mb chromosome 11 segment in its ancestral state and one copy of the same segment with the cholesterol deficiency mutation. We detected a single structural variant, homozygous in the affected case and heterozygous in the non-affected carrier male. The genetic makeup of this key animal provides extremely strong support for the causality of this mutation. The mutation represents a 1.3kb insertion of a transposable LTR element (ERV2-1) in the coding sequence of the APOB gene, which leads to truncated transcripts and aberrant splicing. This finding was further supported by RNA sequencing of the liver transcriptome of an affected calf. The encoded apolipoprotein B is an essential apolipoprotein on chylomicrons and low-density lipoproteins, and therefore, the mutation represents a loss of function mutation similar to autosomal recessive inherited familial hypobetalipoproteinemia-1 (FHBL1) in humans. Our findings provide a direct gene test to improve selection against this deleterious mutation in Holstein cattle.