Serotonin reuptake inhibition does not enhance short term modulation of the exercise ventilatory response.

Increased respiratory dead space causes a serotonin (5-HT) dependent augmentation of the exercise ventilatory response known as short term modulation (STM). Contrary to predictions, 5-HT reuptake inhibition with fluoxetine failed to enhance, and even impaired STM with large dead space volumes (0.4-0.6 L). In this study, we tested the hypotheses that: (1) fluoxetine similarly impairs STM with smaller dead space volumes (0.2 L); whereas (2) acute 5-HT release and reuptake inhibition with fenfluramine would enhance STM. Ventilatory and blood gas measurements were made on five goats (37-58 kg) during rest and exercise, with the mask alone or with increased dead space (0.2 L). STM protocols were performed following chronic fluoxetine (>/=21 days, 1 mg/kg, SQ, SID) and acute fenfluramine administration (1 mg/kg, IV). Following fluoxetine, STM was partially impaired. Fenfluramine had no detectable effects on STM. The data suggest that: (1) chronic fluoxetine diminishes STM, possibly via down-regulation of relevant 5-HT receptors, and (2) drugs that release 5-HT acutely do not enhance STM.

Effects of serotonin re-uptake inhibition on ventilatory control in goats.

Fluoxetine (Prozac) inhibits serotonin (5-HT) re-uptake. thereby enhancing serotonergic effects. Since serotonin is known to affect ventilation in a variety of circumstances, we investigated the effects of chronic serotonin re-uptake inhibition with fluoxetine on selected ventilatory responses including: (1) eupnea; (2) the hypercapnic ventilatory response at rest; (3) the exercise ventilatory response and (4) repeated trials of hypercapnic exercise. Ventilatory and arterial blood gases were measured in goats (n = 5) at rest, during steady-state treadmill exercise, and during successive rest/exercise trials with increased respiratory dead space (0.4-0.6 L). Fluoxetine was administered (> or = 4 weeks, 1 mg/kg, SQ, SID) and protocols were repeated. Following fluoxetine, PaCO2 was increased in most conditions studied; however, no differences were seen in exercise PaCO2 regulation or ventilatory responses pre- versus post-fluoxetine. We conclude that chronic fluoxetine slightly depresses respiratory control at rest, but, has minimal effects during exercise or with mild hypercapnia during rest or exercise in goats.

Nosocomial transmission of Cryptosporidium in a veterinary hospital.

An outbreak of cryptosporidiosis occurred at a veterinary hospital, involving multiple species, including humans. The index case was an infected dairy calf that presented with diarrhea. Several other cases of cryptosporidial diarrhea subsequently developed during a 1-month period. The key features of this outbreak were the multiple species affected, the increased morbidity in immunocompromised neonates, and the failure of implemented control measures to contain the disease.

Actinobacillus suis septicaemia in two foals.

A 24-hour-old Hackney ony filly developed signs of weakness, depression and a poor suck reflex, with harsh lung sounds over both fields, and a 48-hour-old Arabian colt from a normal birth which had sucked vigorously developed loose stools and became depressed, weak and anorectic. Both foals had serum IgG concentrations greater than 800 mg/dl, but each had a severe neutropenia with a left shift, and blood cultures from both of them yielded Actinobacillus suis. The A suis isolates had different antimicrobial susceptibility patterns and, in the case of the Arabian, the isolate was resistant to commonly used broad spectrum antimicrobial agents.