2005 - 74 (6)

A 25-year-old Belgian Warmblood mare with pre-existing atrial fibrillation was presented for surgical treatment of sinusitis. Echocardiography evidenced signs of compromised cardiovascular function, including a decreased contractility of the left ventricle and mitral valve insufficiency. The horse was treated with 2.2 µg/kg digoxin IV, followed by 11 µg/kg orally twice a day for one week before surgery. Premedication consisted of 0.02 mg/kg acepromazine IM and 80 µg/kg romifidine IV. Anesthesia was induced with 0.06 mg/kg midazolam and 2.2 mg/kg ketamine IV and maintained with isoflurane in oxygen. During the anesthesia, a continuous rate infusion with lidocaine (bolus 1.5 mg/kg, then 1.7 mg/kg/h) was administered and a temporary ventricular pacing unit, placed preoperatively, was available to treat possible bradycardia. Dobutamine was used to increase blood pressure but was accompanied by an obvious increase in heart rate. No major problems were encountered during the course of the anesthesia and recovery.

Scrapie resistance and susceptibility in sheep are genetically controlled. The occurrence of natural and experimental scrapie has been linked to polymorphisms of the sheep’s prion protein (PrP) gene at position 136 (V-A), 154 (R-H) and 171 (Q-R-H). The ovine alleles VRQ and ARQ seem to be related to a higher susceptibility, while the alleles ARR and AHQ coincide with a low susceptibility to scrapie infection. Selection of sheep with scrapie-resistant genotypes (ARR/ARR) is currently one of the most important objectives of the sheep breeding associations. During the last 2 years, however, new data has become available relating to TSE cases in TSE-resistant sheep in several EU member states, including the Nor98 strain and other atypical TSE cases carrying the ARR allele. However, these findings could have major implications for the national breeding programs in several EU member states. The present paper describes the second natural atypical TSE case in a sheep with a scrapie-resistant genotype (ARR/ARQ) detected via active surveillance in Belgium, in addition to the previously detected ARR/ARR case. The Western Blot pattern of both sheep corresponds with that of the Nor98 strain. The continued appearance of new “atypical” TSE cases in sheep with scrapie-resistant genotypes undermines the purpose and efficacy of the breeding programs.

Acute hepatoencephalopathy due to ingestion of Senecio jacobaea is described in five horses. Diagnosis was based on history, clinical findings, ultrasonography, laboratory results and postmortem examination. Blood analysis revealed decreased levels of urea and increased levels of ammonia, gamma-glutamyl transferase, bile acids and total bilirubin. As no specific treatment for pyrrolizidine alkaloid intoxication exists, therapy was mainly supportive. None of the five horses survived. Because of the poor prognosis, prevention of the disease, by means of pasture management and exclusion of these plants from hay or silage, is mandatory.

In this study, the depressive effects of AFB1 on the embryonic development of chicken thymus were determined by histological methods and by histochemical demonstration of alpha-naphthyl acetate esterase (ANAE) enzyme. ANAE positivity frequencies of peripheral blood lymphocytes (PBL) were also determined. Embryonic stages were determined according to the Hamburger-Hamilton (H-H) scale. Thymic development was quite similar on day 7 of incubation in all control and AFB1 groups. In contrast, the development was substantially impaired and retarded on day 10 of incubation in the 20 and 40 ng/egg AFB1 groups. The ANAE positivity was first detected on the 18th day of incubation in a minority (2%) of PBL. The proportions of PBL and their ANAE positivity frequencies were significantly (P<0.05) lower in AFB1 treated groups than in the controls on the day of hatching.