Julio Larenas

Efecto de la densidad poblacional y temperatura en truchas arco iris (Oncorhynchus mykiss) inoculadas con Piscirickettsia salmonis

En el presente estudio se reporta el efecto concomitante de tres temperaturas diferentes del agua y dos densidades poblacionales sobre truchas arco iris (Oncorhynchus mykiss) inoculadas experimentalmente con P. salmonis. Los peces fueron inoculados intraperitonealmente con el agente rickettsial (cepa LF-89), utilizando 0.2 ml provenientes de una suspension de cultivo celular infectado con un titulo de 105.8 TCID50/ml. Las truchas fueron divididas en tres grupos experimentales segun la temperatura del agua: 8d, 14d y 18dC. A su vez, cada grupo de temperatura fue subdividido de acuerdo a la densidad poblacional de 5 k/m3 o 20 k/m3 y mantenidos por 35 dias en acuarios. Los resultados demostraron mortalidades de un 24% en el grupo mantenido a 14dC y 20 k/m3, lo cual fue estadisticamente superior al resto de los grupos (ps0.001). Un efecto de sinergismo fue demostrado entre 14dC y 20 k/m3 para desarrollar la enfermedad. En los otros grupos experimentales no hubo mortalidades o bien estas no fueron superiores a un 2%. Muestras de heces provenientes de peces moribundos demostraron la presencia P. salmonis. El presente estudio sugiere que el efecto de la densidad poblacional y la temperatura del agua pueden ser factores importantes en la presentacion de la piscirickettsiosis

Protective oral vaccination against infectious salmon anaemia virus in Salmo salar

Infectious salmon anemia (ISA) is a systemic disease caused by an orthomyxovirus, which has a significant economic impact on the production of Atlantic salmon (Salmo salar). Currently, there are several commercial ISA vaccines available, however, those products are applied through injection, causing stress in the fish and leaving them susceptible to infectious diseases due to the injection process and associated handling. In this study, we evaluated an oral vaccine against ISA containing a recombinant viral hemagglutinin-esterase and a fusion protein as antigens. Our findings indicated that oral vaccination is able to protect Atlantic salmon against challenge with a high-virulence Chilean isolate. The oral vaccination was also correlated with the induction of IgM-specific antibodies. On the other hand, the vaccine was unable to modulate expression of the antiviral related gene Mx, showing the importance of the humoral response to the disease survival. This study provides new insights into fish protection and immune response induced by an oral vaccine against ISA, but also promises future development of preventive solutions or validation of the current existing therapies.

Histopathological findings in Gonads of Xenopus laevis from Central Chile

In order to perform a gonadal histological study, adult specimens of Xenopus laevis at four sites in the central region of Chile were captured. The results showed no alterations in gonadal female instead the males showed testicular histological abnormalities, features of endocrine disruption, possibly generated by environmental pollution.A fin de realizar un estudio histologico gonadal, se capturaron ejemplares adultos de Xenopus laevis en cuatro sitios de la region central de Chile. Los resultados evidenciaron ausencia de alteraciones gonadales en hembras, en cambio, los machos presentaron anormalidades histologicas testiculares caracteristicas de disrupcion endocrina, posiblemente generadas por contaminacion ambiental.

New reports of helminthes in captive exotic psittacine birds in Chile

A pesar de su importancia, la fauna helmintica de aves psitacidas ha sido poco investigada en Chile. En el presente estudio se reporta la presencia de Tetrameres sp. en Cyanoramphus novaezelandiae, de Schistorophus sp. en Platycercus flaveolus y de Dispharynx nasuta en P. flaveolus, Platycercus eximius, Platycercus elegans , Polytelis alexandrae, y C. novaezelandiae en diferentes aviarios de la Region Metropolitana de Chile. Los primeros casos de Ascaridia platyceri en P. eximius y C. novaezelandiae son tambien descritos. Ascaridia platyceri y D. nasuta fueron implicados como la causa de enfermedades serias y fatales en estas aves psitacidas exoticas, mientras que Schistorophus sp. y Tetrameres sp. fueron clinicamente menos significativos

Aortic regurgitation associated with chronic bacterial endocarditis in one adult thoroughbred gelding

This article describes chronic bacterial endocarditis as the cause of aortic regurgitation in a 25-year-old Thoroughbred used for horseback riding. The horse presented signs of depression, exercise intolerance, and weight loss. A pandiastolic murmur was identified, but no other clinical signs of bacterial endocarditis were identified. Haematological, serum biochemical, and urine analyses did not show any particular abnormalities. Electrocardiography showed a physiological dysrhythmia that was not pertinent to this case. Echocardiography revealed left ventricle (LV) dilatation and a nodule in the left coronary cusp of the aortic valve associated with regurgitation. Based on the prevalence of aortic valve pathology in geriatric horses, a noninfectious condition with a myxomatous noninflammatory infiltrate was suspected; therefore, no special treatment was prescribed due to the absence of heart failure. Several months later, the animal was euthanised after experiencing a femur fracture. At necropsy, the horse showed an eccentric left ventricle hypertrophy and 2 nodules in the left coronary cusp of the aortic valve. Histological examination revealed the presence of bacteria, which led to the diagnosis of chronic bacterial endocarditis.

Cinética del algor mortis: Primeros pasos para estimar data de muerte en animales

SUMMARY The time elapsed from death until the moment the corpse equals its temperature to ambient temperature is known as “Early Post Mortem Interval”, and during this period the decrease in body temperature –algor mortis– is a useful routine measure to estimate postmortem interval (IPM) in human forensics. Early IPM for humans is 24 hours on average, but there is no information regarding animals that allow the use of algor mortis as an estimator of IPM. In this study, the core body and ambient temperature were measured continuously in 50 dead laboratory rats. Results showed that, on average, early IPM was 11 hours 14 minutes, ranging between 8 hours and 32 minutes and 17 hours with 7 minutes. An equation that estimates the IPM in rats was also obtained, minimizing residuals. This is the first experimental study aimed to obtain parameters to estimate the postmortem interval from algor mortis in animals.