Cardiovascular and respiratory effects of ketamine infusions in isoflurane-anesthetized dogs before and during noxious stimulation

OBJECTIVE: To characterize the effects of ketamine administration on the cardiovascular and respiratory systems and on acid-base balance and to record adverse effects of ketamine in isoflurane-anesthetized dogs. ANIMALS: 6 healthy adult mongrel dogs. PROCEDURE: Dogs were anesthetized with isoflurane (1.25 times the individual minimum alveolar concentration) in oxygen, and ketamine was administered IV to target pseudo-steady-state plasma concentrations of 0, 0.5, 1, 2, 5, 8, and 11 microg/mL. Isoflurane concentration was reduced to an equipotent concentration. Cardiovascular, respiratory, and acid-base variables; body temperature; urine production; and adverse effects were recorded before and during noxious stimulation. Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, left ventricular stroke work index, right ventricular stroke work index, arterial oxygen concentration, mixed-venous oxygen concentration, oxygen delivery, oxygen consumption, oxygen extraction ratio, alveolar-arterial oxygen partial pressure gradient, and venous admixture were calculated. Plasma ketamine and norketamine concentrations were measured. RESULTS: Overall, ketamine administration improved ventilation, oxygenation, hemodynamics, and oxygen delivery in isoflurane-anesthetized dogs in a dosedependent manner. With the addition of ketamine, core body temperature was maintained or increased and urine production was maintained at an acceptable amount. However, at the higher plasma ketamine concentrations, adverse effects such as spontaneous movement and profuse salivation were observed. Myoclonus and dysphoria were observed during recovery in most dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Infusion of ketamine appears to be a suitable technique for balanced anesthesia with isoflurane in dogs. Plasma ketamine concentrations between 2 to 3 microg/mL elicited the most benefits with minimal adverse effects.     

Participation of Rhipicephalus sanguineus (Acari: Ixodidae) in the epidemiology of canine visceral leishmaniasis

The vectorial competence of the tick Rhipicephalus sanguineus is discussed in relation to the epidemiology of canine visceral leishmaniasis, taking into account its strict association with dogs and the low indices of natural infection presented by its known vector, the phlebotomine sand fly Lutzomyia longipalpis. In order to evaluate natural infection by Leishmania chagasi and the infectivity of these parasites in the tick, 39 specimens (6 females, 11 males and 22 nymphs) of R. sanguineus were removed from 21 dogs showing diverse symptoms of zoonotic visceral leishmaniasis (ZVL). Six ticks (15.4%) gave positive results for the genus Leishmania using the PCR technique. To determine the infectivity of the parasites, 36 hamsters were inoculated orally and peritoneally with macerates of ticks removed from nine dogs symptomatic for visceral leishmaniasis. After 6 months the hamsters were sacrificed and necropsied. Serum was removed for IFAT, as well as spleen and liver fragments to make imprint smears and for PCR. Eight (88.9%) of these dogs presented ticks that were infective for 14 hamsters (41.2%), 12 (85.7%) of them infected peritoneally and two (14.3%) orally. PCR revealed 27 smears (40.9%) to be positive, 20 (62.5%) of them infected peritoneally and seven (20.6%) orally. IFAT showed 14 positive animals (41.2%). Based on these findings, we suggest that the vectorial capacity of R. sanguineus for L. chagasi should be evaluated further, opening new perspectives in the epidemiology of ZVL.     

Physicochemical changes in the hull of corn grains during their alkaline cooking

The alkaline cooking of corn in a solution of Ca(OH)2 to produce corn-based foods is oriented to make corn proteins available, to incorporate Ca to the cooked grains, and also to remove the corn hull. This process (nixtamalization) is known in Mexico and Guatemala from prehispanic times; however, the effect of the alkaline cooking on the corn hull remains poorly documented. In this work, the physicochemical changes that take place in the corn hull during its cooking in a saturated solution of Ca(OH)2 were studied using infrared, X-ray diffraction, 13C cross-polarization/magic-angle spinning (CP/MAS) NMR, confocal imaging microscopy, differential scanning calorimetry, and thermogravimetry techniques. The main effect of this treatment on the hull is the removal of hemicelluloses and lignin, increasing the hull permeability and, as a consequence, facilitating the entry of the alkaline solution into the corn kernel. No significant changes were observed in the cellulose fiber network, which remains as native cellulose I, with a crystalline index, according to 13C CP/MAS NMR spectra, of 0.60. The alkaline treatment does not allow the cellulose fibers to swell and their regeneration in the form of cellulose(II). It seems any attempt to make use of the Ca binding capacity of the hull to increase the Ca availability in nixtamalized corn-based foods requires a separated treatment for the hull and kernel. On alkaline cooking, the hull hemicellulose fraction dissolves, losing its ability to bind Ca as a way to incorporate this element into foods elaborated from nixtamalized corn.     

Seroprevalence of Toxoplasma gondii in sows from slaughterhouses and in pigs from an indoor and an outdoor farm in Argentina

The objective of the present study was to determine the prevalence of Toxoplasma gondii antibodies from slaughter sows and from pigs raised at an indoor and an outdoor swine farm. Serum samples were obtained from 230 slaughter sows belonging to 83 farms distributed in 5 provinces. Blood samples were collected monthly from pigs of different ages from an intensive management indoor farm (farm 1). A cross-sectional study was carried-out from an outdoor farm (farm 2). All sera were tested for T. gondii antibodies by the modified agglutination test (MAT), using formalin-fixed tachyzoites as antigen. An antibody titer > or =1:25 was considered positive. Antibodies to T. gondii were detected in 87 (37.8%) of 230 sows sera. Distribution among provinces was: 37.1% from Santa Fe, 62.8% from Buenos Aires, 3.3% from San Luis, 58.7% from La Pampa and 24% from Córdoba. Four of 88 (4.5%) serum samples from farm 1 had antibodies to T. gondii and none of the negative pigs seroconverted. However, 45 of 112 samples from farm 2 were positive (40.2%) with the following distribution: sows 100%; nursery 40%; growers 13.8% and fatteners 20%. It is concluded that the prevalence of T.gondii antibodies among sows seems to be quite variable. T. gondii prevalence was related to the facilities and management of the farm.     

Azotemia and mortality among Babesia microti-like infected dogs

Babesia microti-like piroplasms are a recently recognized cause of illness in dogs in northwest Spain. Our objective was to describe the clinical characteristics and investigate the risk factors for azotemia and death among 58 B microti-like infected dogs. Twenty-one of the 58 (36%) dogs were azotemic at the time that the infection was diagnosed. The case fatality rate during the following week was 22%. Dogs with azotemia at the time of diagnosis were 10 times (95% CI, 3.26-28.8) more likely to die during the following week. Azotemia was the main cause of death for B microti-like infected dogs (attributable fraction = 90%). Severe anemia was present in 45 of the 58 (78%) dogs. Azotemic dogs also presented with hyperphosphatemia, hypoalbuminemia, hypercholesterolemia, proteinuria, and high urine protein: creatinine ratios, suggesting a glomerular component to the disease. Age was the only factor significantly associated with the risk of azotemia (P = .042): on average, a 4-year age increase doubled the risk of an infected dog being azotemic. The only factor significantly associated with mortality was azotemia (P = .001). We concluded that B microti-like infection is associated with a high risk of azotemia and mortality.     

Pharmacokinetics of a combination preparation of ampicillin and sulbactam in turkeys

OBJECTIVE: To investigate the disposition kinetics of ampicillin and sulbactam after IV and IM administration of an ampicillin-sulbactam (2:1) preparation and determine the bioavailability of the combined preparation after IM administration in turkeys. ANIMALS: 10 healthy large white turkeys. PROCEDURE: In a crossover study, turkeys were administered the combined preparation IV (20 mg/kg) and IM (30 mg/kg). Blood samples were collected before and at intervals after drug administrations. Plasma ampicillin and sulbactam concentrations were measured by use of high-performance liquid chromatography; plasma concentration-time curves were analyzed via compartmental pharmacokinetics and noncompartmental methods. RESULTS: The drugs were distributed according to an open 2-compartment model after IV administration and a 1-compartment model (first-order absorption) after IM administration. For ampicillin and sulbactam, the apparent volumes of distribution were 0.75+/-0.11 L/kg and 0.74+/-0.10 L/kg, respectively, and the total body clearances were 0.67+/-0.07 L x kg(-1) x h(-1) and 0.56+/-0.06 L x kg(-1) x h(-), respectively. The elimination half-lives of ampicillin after IV and IM administration were 0.78+/-0.12 hours and 0.89+/-0.17 hours, respectively, whereas the corresponding half-lives of sulbactam were 0.91+/-0.12 hours and 0.99+/-0.16 hours, respectively. Bioavailability after IM injection was 58.87+/-765% for ampicillin and 53.75+/-5.35% for sulbactam. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that a regimen of loading and maintenance doses of 300 mg of the ampicillin-sulbactam (2:1) combination/kg every 8 hours could be clinically useful in turkeys. This dosage regimen maintained plasma concentrations of ampicillin > 0.45 microg/mL in turkeys.     

Routes of transmission and consequences of small ruminant lentiviruses (SRLVs) infection and eradication schemes

Small ruminant lentiviruses (SRLV = maedi-visna in sheep and caprine arthritis encephalitis in goats) are distributed throughout most countries of the world, particularly Europe. Laboratories from 16 European countries established collaborations within the framework of a COST (CO-operation in the field of Scientific and Technical Research) action sponsored by the European Union in order to (i) better organize their research programmes on SRLVs and (ii) to coordinate efforts to combat these two diseases. After five years, a consensus conference--the first one in the veterinary medicine field--concluded the work of this network of laboratories by reviewing the present position and discussing three important questions in the field of SRLVs: routes of transmission, consequences of infection and potential role of eradication programmes at either a European or local level, according to the situation in each country or region. This paper brings together existing information regarding these questions and identifies areas for future research.