Investigation of the distance to slaughterhouses and weather parameters in the occurrence of porcine reproductive and respiratory syndrome outbreaks in U.S. swine breeding herds.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically important diseases affecting the swine industry. The main objective of this study was to assess whether sow farm distance to slaughterhouses and meteorological variables were associated with PRRS outbreaks. This case-control study paired 104 sow farms with or without a reported PRRS outbreak (N = 208) during the same period. Data on the distance to the closest slaughterhouse, swine density, presence of an air filtration system, or a neighboring farm, and weather conditions were collected, and a multivariable conditional logistic regression model was created to investigate the association between variables of interest and the occurrence of a PRRS outbreak. Swine density, presence of an air filtration system, presence of a neighboring farm, and PRRS herd-level status before the outbreak were associated with the occurrence of PRRS outbreaks. Farms in areas with higher swine density and nearby swine farms had increased odds of reporting an outbreak compared to farms in low swine density areas and farms having no neighbors. Under the conditions of this study, none of the meteorological variables or the distance to the closest slaughterhouse were associated with occurrence of PRRS outbreaks.

Enquête sur la distance aux abattoirs et les paramètres météorologiques dans l'apparition d'épidémies de syndrome reproducteur et respiratoire porcin dans les troupeaux reproducteurs de porcs aux États-Unis. Le syndrome reproducteur et respiratoire porcin (SRRP) est l'une des maladies les plus importantes sur le plan économique affectant l'industrie porcine. L'objectif principal de cette étude était d'évaluer si la distance entre les élevages de truies et les abattoirs et les variables météorologiques étaient associées aux épidémies de SRRP. Cette étude cas-témoin a apparié 104 élevages de truies avec ou sans éclosion de SRRP déclarée (N = 208) au cours de la même période. Des données sur la distance à l'abattoir le plus proche, la densité porcine, la présence d'un système de filtration d'air ou d'une ferme voisine et les conditions météorologiques ont été recueillies, et un modèle de régression logistique conditionnelle multivariable a été créé pour étudier l'association entre les variables d'intérêt et l'occurrence d'une épidémie de SRRP.La densité porcine, la présence d'un système de filtration de l'air, la présence d'une ferme voisine et le statut du troupeau relativement au SRRP avant l'épidémie ont été associés à l'apparition d'épidémies de SRRP. Les fermes situées dans des zones à forte densité porcine et d'autres fermes porcines à proximité avaient plus de chances de signaler une épidémie que les fermes situées dans des zones à faible densité porcine et les fermes sans voisins. Dans les conditions de cette étude, aucune des variables météorologiques ni la distance à l'abattoir le plus proche n'étaient associées à la survenue d'épidémies de SRRP.(Traduit par Dr Serge Messier).

Cocaine-induced behavioral sensitization and conditioning in male Japanese quail.

Repeated intermittent cocaine treatment often results in behavioral sensitization or an augmented response to cocaine. Cocaine-induced behavioral sensitization may be an important contributor to cocaine addiction and abuse. Some studies have also shown that conditioned drug effects may play a role in behavioral sensitization. The current experiment utilized a simplified discrimination paradigm to investigate behavioral sensitization and the role of conditioning in an avian species. Male Japanese quail received alternating injections of cocaine (10 mg/kg i.p.) paired with a context and saline injections paired with a different context. They were later given a cocaine challenge followed by and a saline challenge in the drug-paired context. Results showed that birds that received cocaine paired with one context also demonstrated behavioral sensitization to a cocaine challenge given after a withdrawal period and they developed conditioning to the drug-paired context. A saline control and a control group that received cocaine that was not paired with the test context failed to demonstrate sensitization or conditioning. The findings demonstrate visual discrimination learning and implicate the role of Pavlovian conditioning in behavioral sensitization.

Cocaine sensitization in male quail: temporal, conditioning, and dose-dependent characteristics.

Chronic cocaine administration typically results in increased locomotor activity, known as behavioral sensitization. Investigating the time course of locomotor activity across trials may provide a more detailed analysis of the temporal changes that might occur within sensitization. Prior research with rodents shows that the peak of locomotor activity shifts from acute to chronic drug administration. The purpose of the current experiment was to investigate acute versus chronic cocaine effects on locomotor activity in an avian species, Japanese quail, and to investigate whether this phenomenon is dose-dependent. Subjects received daily i.p. injections of saline or 5, 10, or 20 mg/kg cocaine for 20 days. Following each injection, birds were placed in standard locomotor activity chambers, and activity was recorded for 150 min. A cocaine challenge was given after a ten-day withdrawal period. Two retraining trials were given to re-establish cocaine responding prior to a saline challenge in the drug-paired environment. Results showed that repeated administration of the 10 mg/kg dose of cocaine enhanced activity across 120 min compared with acute administration. In contrast, repeated administration of the 20 mg/kg dose resulted in greater cocaine-induced activity for 60 min compared with acute administration. In addition, behavioral sensitization was shown to be dose-dependent and appeared to be due, at least in part, to conditioning.