Prevalence of Cryptosporidium sp in equids in Louisiana

In 1985, 22 pony foals reared in a helminth-free environment were tested daily for oocysts of Cryptosporidium sp by use of fecal flotation. Oocysts were found in all foals. Oocysts were first observed in feces collected from foals 9 to 28 days after birth. The mean period of oocyst shedding was 10 days and ranged from 2 to 18 days in individual foals. Diarrhea was observed in 14 of 22 (64%) foals and began before the period of oocyst shedding. Fecal samples also were examined for other infective agents. Salmonella poona was isolated from 1 foal that did not have diarrhea, and coronavirus particles were observed in the feces of 2 foals with diarrhea. Cryptosporidium sp oocysts also were observed in feces of 2 of 17 Thoroughbred foals, 3 of 14 Quarter Horse foals, and 3 of 26 pony foals reared on pastures with their dams. Samples from pasture-reared foals were collected at irregular intervals. Of the 11 Cryptosporidium-positive fecal samples collected from pastured foals, 2 were from foals with diarrhea. A similar survey was conducted during the 1986 foaling season, using the same procedures. Examination of 300 samples from 58 Quarter Horse, Arabian, and pony foals did not detect oocysts. Daily examination of feces from 10 pony foals reared under helminth-free conditions for 30 days also failed to detect Cryptosporidium oocysts.     

Antibodies to bovine serum albumin in swine sera: implications for false-positive reactions in the serodiagnosis of African swine fever

Antibodies to bovine serum albumin were detected in swine sera by use of an immunoblotting technique. Such sera had false-positive reactions, as determined by results of African swine fever virus serodiagnostic techniques when bovine serum albumin was a contaminant in the soluble cytoplasmic antigen obtained from infected cells cultured in the presence of bovine serum. The soluble cytoplasmic antigen obtained from cell cultures infected with African swine fever virus in the presence of porcine serum did not react with the false-positive sera and, therefore, was used for African swine fever virus serodiagnostic methods, with 0% false-positive results.     

Genomic variability among globally distributed isolates of equine arteritis virus.

Equine arteritis virus (EAV), a non-arthropod borne togavirus, has been shown to have a global distribution. To date, no major antigenic variation has been demonstrated between EAV isolates from different geographic origins. In this study, the genomic RNA of EAV isolates obtained from horses of different breeds in various countries around the world was oligonucleotide fingerprinted. Comparisons of these fingerprints were used to determine the extent of genomic variation among such isolates. Comparisons among isolates from North American horses revealed, for the most part, oligonucleotide homologies of less than 60%. Only 29 of the 98 comparisons revealed greater than 60% oligonucleotide homology. Nonetheless, several comparisons indicated a close epidemiologic relationship between isolates from horses of different breeds located in different states. Though all European isolates were of Standardbred origin and were from horses located in northern European countries, the majority had oligonucleotide homologies of less than 60%. Where oligonucleotide homology was apparent, it was, with one exception, greater than 70%. The two isolates from New Zealand had 93.2% oligonucleotide homology. This is indicative of an extremely close epidemiologic relationship. Comparisons between EAV isolates from around the world revealed oligonucleotide homologies between viruses from North America, Europe and New Zealand. In several instances, this homology was greater than 70% and in one case greater than 80%. No oligonucleotide homology was evident in comparisons involving the virus from South Africa. The high level of genomic conservation between certain EAV isolates of disparate geographic origins may reflect dissemination of the virus associated with the international movement of horses. The extent of genomic variation demonstrated between most of the EAV isolates used in this study confirms the need for further investigation of genomic heterogeneity among strains of this virus before techniques that rely upon nucleic acid hybridization can be effectively applied as diagnostic procedures.     

Differentiation of Staphylococcus sciuri Strains Isolated from Free‐Living Rodents and Insectivores

Twenty‐nine Staphylococcus sciuri strains isolated from free‐living insectivores and rodents were comparatively analysed for their biochemical capacities and their SmaI macrorestriction patterns. The 29 S. sciuri isolates represented 21 different biotypes and 22 different SmaI macrorestriction types. This observation confirmed that S. sciuri isolates obtained from insectivores and rodents living in natural environments constituted a heterogeneous population. Cluster analysis revealed that the macrorestriction patterns and the biochemical profiles matched in some cases. However, S. sciuri isolates that exhibited the same or closely related biochemical profiles were also found to be associated with different macrorestriction patterns. Analysis of the 29 S. sciuri isolates for their plasmid content and their sensitivity to antimicrobial agents showed that most of the isolates were plasmid‐free and susceptible to all antimicrobial agents tested.     

Effects of low and high calcium intake prepartum on calcium mobilization rate around parturition in dairy cows

Forty-one dairy cows were fed a low (LCa-13 g/d) and a high (HCa-83.5 g/d) calcium ration in the 8 weeks prior to parturition and the effect on the Ca mobilization rate around parturition was studied. Plasma Ca values were stable in the LCa group around parturition. In the older cows of the HCa group a very slight decrease in the mean plasma Ca was observed: 2.58 mmol/l at 12-36 h ante partum decreased to 2.38 mmol/l at parturition. Hypocalcaemia, which commonly occurs around parturition, did not occur in 40 of the cows. A subclinical hypocalcaemia (1.8 mmol/l) occurred in one cow (parity 10) from the HCa group. To assess the efficiency of Ca mobilization, a severe hypocalcaemia (1.0 mmol/l) with clinical signs was induced by means of Na2EDTA infusion (0.90 mmol/min), starting at 10 h post-partum. The older cows in the LCa group required more Na2EDTA than those in the HCa group. Higher urinary hydroxyproline excretion in the week before parturition in the LCa than in the HCa group suggested a higher bone turnover. Plasma PTH levels around parturition were not significantly different between the groups. The amount of colostrum milked out in the first 10 h post-partum did not influence Ca homeostasis around parturition. The results contradict those of many other experiments in which hypocalcaemia was observed in cows ingesting high levels of Ca. It is concluded that the restricted feed intake prepartum possibly had a favourable effect on Ca homeostasis.     

Leeching as initial treatment in a cat with polycythaemia vera.

Polycythaemia vera was diagnosed in a three-year-old domestic shorthaired cat referred because of seizures and a high packed cell volume (PCV). Laboratory examination revealed severe erythrocytosis (PCV 79 per cent). Diagnosis was reached by excluding causes for relative and secondary absolute polycythaemia. As phlebotomy proved impossible for initial treatment due to hyperviscosity, four leeches were used to suck blood and the PCV was consequently reduced to 64 per cent. A further 24 hours later, when bleeding at the sites of sucking had stopped, the PCV was 56 per cent. Long-term management of the condition was achieved with hydroxyurea (100 mg/cat once daily) and intermittent phlebotomy. Initial treatment using leeches in cases of polycythaemia vera is a simple, non-invasive, well tolerated and effective method where phlebotomy is not possible.