Increased mitral valve regurgitation and myocardial hypertrophy in two dogs with long-term pimobendan therapy.

The aim of this article is to describe original adverse effects in two dogs chronically treated with the inodilator pimobendan. We report a German shepherd (i.e., dog 1) and a poodle (i.e., dog 2) that were referred to our cardiology unit after receiving pimobendan for 10 and 5 mo, respectively. In both dogs, conventional echo-Doppler examination demonstrated mitral valve regurgitation and myocardial hypertrophy. Tissue Doppler imaging (TDI) was performed in the first case and revealed an abnormal relaxation phase. After the first examination, pimobendan administration was stopped in both cases and dogs were re-examined 3 and 1 mo later, respectively. Mitral valve regurgitation assessed by echocardiography decreased in both dogs, and the systolic heart murmur disappeared in dog 1. Importantly, most echocardiographic and TDI parameters tended to normalize in dog 1, suggesting, at least partial reversal of both myocardial hypertrophy and relaxation abnormality produced during inodilator therapy. This is the first report to describe an increase in mitral regurgitation under clinical conditions in dogs treated with pimobendan. We also suggest that pimobendan may induce ventricular hypertrophy. However, prospective studies are needed to confirm this observation.

In vitro properties and experimental pathogenic effect of three strains of feline immunodeficiency viruses (FIV) isolated from cats with terminal disease.

Three strains of virus isolated from peripheral blood mononuclear cells (PBMC) of sick cats were identified as feline immunodeficiency virus (FIV) on the basis of in vitro cytopathic effect, T-lymphotropism, ultrastructural morphology and magnesium-dependent reverse-transcriptase activity. The pathogenic properties of two isolates were studied in 13 experimentally infected cats. The primary phase of infection was characterised by a range of haematological (neutropenia, lymphopenia, presence of atypical lymphocytes) and clinical alterations (fever, various signs lasting several weeks, generalised lymphadenopathy persisting for several months) and specific seroconversion. A correlation between the inoculated dose of virus and the intensity and duration of clinical signs was observed. The primary phase was followed in the 10 surviving cats by a stage of asymptomatic seropositivity of undetermined duration but which has persisted for over 35 months for the earliest infections. Viruses reisolated several weeks or months after experimental infection retained the same in vitro properties as the initial isolates.

[Induction of cytochrome P 450 by phenobarbital in cats]. / Induction du cytochrome P 450 par le phénobarbital chez le chat.

Phenobarbital administration to the Cat an animal hypersensitive to the actions of many toxic substances or to physiological compounds such as hormones, does not produce cytochrome P 450 induction. Consequently, hepatic storage of retinol remains unchanged. The specific and original characteristics of the Cat in this field are underlined by these results.

Results of an epidemiological investigation on viral arteritis in France and some other European and African countries.

An original microplate seroneutralization technique was developed in order to study the existence of antibodies against equine viral arteritis. The technique involves a high amount of complement, and has allowed to demonstrate antibodies in 18.5% out of 4,037 horses examined. Titers varied not or little during periods as long as 6 years. Among 3,324 sera samples from French horses, a 15.2% frequency of antibodies was shown. The infection level was not very different between breeds, which is different from results obtained in the U.S.A. with another technique. The infection level increased regularly from 1 to 20 years of age, but, for a constant age, the percentage decreased with the year of birth, between 1950 and 1970. Eight individual infection cases have been identified between 1966 and 1974. It seems that more often the disease occurs without clinical symptoms, or sometimes manifests itself through sporadic abortion. Serological marks of infection have been found at variable levels in all the countries of Europe and Africa investigated. In Africa, a higher level (37.1% among 468 sera) was observed.