The influence of fasting on blood glucose,triglycerides, cholesterol,and alkaline phosphatase in rats

Serum concentrations of glucose, cholesterol, triglycerides, and serum alkaline phosphatase activity were measured over different periods of time of food deprivation in male rats. Thirty percent of non-fasted rat's sera was found to be lipemic. At 16 hours of fasting, glucose levels dropped by 30% compared to the level of the non-fasting control group, and remained at a relatively constant level for up to 48 hours of fasting. Triglyceride concentrations decreased at 16 hours after fasting. Serum cholesterol levels were not changed at any of the fasting periods compared to the non-fasted control group. Alkaline phosphatase activity was decreased at 8 hours of fasting, with further declines in activity of the serum enzyme seen at 16, 24, and 48 hours of fasting. It was concluded that at 16 to 18 hours fasting, a non-absorptive state had been reached in male rats.     

The influence of sex and gonadectomy on hepatic and brain fatty acid composition,lipogenesis and β‐oxidation

The aim of this study was to investigate the influence of sex and castration of rats on liver and brain fatty acid profile and liver mRNA expression of genes involved in lipogenesis and β‐oxidation. Castration significantly increased body weight and liver index and decreased serum triglyceride content in the female rats. The fatty acid composition of the liver tissue was influenced by sex and castration. Male rats had higher content of C16:0, C18:1n7, C18:2n6 and C22:5n3, while female rats had higher content of C18:0, C20:4n6 and C22:6n3. Castration of male rats decreased differences caused by sex for C18:2n6, C20:4n6 and C22:6n3. Values for C16:1n7 were higher in the castrated male rats in comparison with all other groups. Liver phospholipids showed a distribution of fatty acids similar to the total lipids. Brain total lipids and phospholipids were not influenced by sex or castration. Castration increased ?6D gene expression in both the sexes, while ?5D and ?9D increased in females and males respectively. Gonadectomy increased expression of the FASN gene in the females and decreased CPT1 and ACOX1 gene expression in the liver tissue of male rats. The observed results of lipid peroxidation, measured by TBARS, were the lowest in the intact females in comparison with all other groups. In conclusion, sex strongly influences both SFA and PUFA in liver tissue, and castration decreases these differences only for PUFA. Castration also influences the expression of the genes involved in lipid metabolism differently in male and female rats, with an increase in lipogenic genes in female rats and a decrease in key genes for mitochondrial and peroxisomal β‐oxidation in male rats.     

Fertility control of Rattus nitidus using quinestrol: effects on reproductive organs and social behavior

Fertility control has been identified by studies in the laboratory and the field as a more appropriate and long‐term control strategy for rodent pests than lethal control. In this study, we investigated the effects of quinestrol on mass of reproductive organs and on social behaviors in female and male Himalayan field rats (Rattus nitidus). A total of 16 adult females and 16 adult males were randomly assigned to 4 groups. One male and one female group were fed rice with 0.005% quinestrol by weight for 7 days, and another 2 groups were fed rice only. After 7 days, rats were assigned to 10 min dyadic encounters between groups, and investigation, aggression, defense and attack latency were quantified. All animals were killed on day 10, and reproductive organs were dissected and weighed. Dyadic encounter data showed that there were obvious changes in social behaviors of quinestrol‐treated rats. Quinestrol significantly inhibited the investigative behavior of quinestrol‐treated males toward control females in Rattus nitidus, but seldom affected investigation between control males and quinestrol‐treated females. Aggression of control females toward quinestrol‐treated males was higher than that of quinestrol‐treated females, and defense of quinestrol‐treated males toward control females was more remarkable than that of control males. Quinestrol remarkably decreased wet masses of epididymis and spermotophore in males and ovaries in females, but had no effect on wet masses of testes and uteri after quinestrol treatment. These results indicate that the anti‐fertility effects of quinestrol on R. nitidus are attributed to not only suppressing reproductive organs but also impacting social behaviors associated with territory defense and mate choice.     

Effect of a short-term fast on intestinal disaccharidase activity and villus morphology of piglets suckling insulin-like growth factor-I transgenic sows

The objectives of this study were to use transgenic sows that overexpress IGF-I in milk to investigate the effect of a short-term fast on piglet intestinal morphology and disaccharidase activity and to determine how milk-borne IGF-I influences the response to fasting. After farrowing, litters were normalized to 10 piglets. On d 6, piglets (n = 30) suckling IGF-I transgenic (TG) sows and piglets (n = 30) suckling nontransgenic sows (control) were assigned randomly to three treatments: fed piglets (0 h), which remained with the sow until euthanized on d 7, or fasted piglets, which were removed from the sow at either 6 or 12 h before euthanasia on d 7. Serum IGF-I and IGFBP, intestinal weight and length, jejunal protein and DNA content, disaccharidase activity, and villus morphology were measured. Fasting for 12 h resulted in a negative weight change between d 6 and 7 (quadratic response to fasting; P < 0.001). Piglets suckling TG sows tended to have greater intestinal length (P = 0.068), but no effect of IGF-I overexpression was noted for intestinal weight. Fasting, however, resulted in linear (P < 0.001) and quadratic (P = 0.002) decreases in intestinal weight. Serum IGF-I did not differ between control and TG sows, but decreased linearly (P = 0.003) with fasting. Serum IGFBP-4 decreased (linear and quadratic; P < or = 0.02) with fasting, whereas IGFBP-1 increased quadratically (P < 0.001) with fasting. Jejunal villus height, width, and crypt depth were all increased with fasting (linear and quadratic; P < 0.04). Disaccharidase activity was not affected by fed state; however, piglets suckling TG sows had greater jejunal lactase-phlorhizin hydrolase (P < 0.01) and sucrase-isomaltase (P = 0.02) activities than control piglets. In summary, intestinal weight, villus morphology, serum IGF-I, serum IGFBP-1 and -4, and piglet BW change were altered (P < or = 0.02) in response to fasting. Thus, the duration of food deprivation before euthanization should be considered when designing experiments to assess intestinal development or the IGF axis, as the magnitude of differences between the fed and fasted state may exceed those expected as a result of experimental treatment.     

Fasting reduces the incidence of vincristine‐associated adverse events in dogs

Fasting has been shown to decrease chemotherapy‐associated adverse events (AEs), in part through insulin‐like growth factor (IGF‐1) reduction, and may induce a protective effect on normal cells during chemotherapy treatment in mice and people. The purpose of this study was to evaluate the effect of fasting on constitutional, bone marrow and gastrointestinal (GI) AEs, and serum glucose, IGF‐1 and insulin levels in dogs receiving vincristine. The study was a prospective, crossover clinical trial in tumour‐bearing dogs. Dogs were randomized to be fasted for 24 to 28 hours prior to and 6 hours following their first or second vincristine treatment, and fed normally for the alternate dose. A significant reduction in nausea, anorexia, lethargy and serum insulin was observed when dogs were fasted; however, no significant differences were found in other GI symptoms, neutrophil count, serum glucose or IGF‐1. Fasting prior to vincristine therapy is a safe and effective treatment modality that helped mitigate constitutional and GI AEs in tumour‐bearing dogs.     

Reproductive Features and Faecal Progesterone Metabolite Profile in Female Ferrets

Elevated post‐partum progesterone metabolite (P₄‐met) levels have been recently postulated to occur in lactating lynxes. The aims of this study were to monitor reproductive features in female ferrets, changes in the faecal P₄‐met concentrations throughout the breeding season and ovarian activity in post‐partum lactating and non‐lactating (NL) female ferrets. Our results indicate that coinciding with the results described in the lynx, elevated faecal P4‐met concentrations occur in lactating ferrets, furthermore, that the duration of elevated secretion of P₄ seems to be dependant on the duration of lactation (P4‐met at delivery, n = 47: <500 ng/g; 5–7 days after delivery, during lactation, n = 47: ≥500–800 ng/g; in females weaned at delivery, n = 4: baseline levels). Three days after ovariohysterectomy of lactating females, P₄‐met concentrations decreased to baseline levels. In lactating females, the ovarian stroma is more active than that in NL ones implicating that the ovary is at least in part responsible for the elevated P4‐met concentrations. Ovaries of lactating females contained many luteinized cells either as luteinized granulose cells in the wall of late pre‐antral/early antral follicles or as corpus luteum (CL)‐like structures. Early resumption of the entire ovarian activity (developed follicles and oestrus) occurs in NL post‐partum females, while final follicular development is blocked (follicles stalls at antral stage) in the lactating ones (however, occasionally lactational oestrus may occur). We suppose that the elevated faecal P4‐met during lactation together with suckling and other hormonal effects may contribute to prevention of early returning to oestrus in nursing female ferrets.     

Endotoxn-induced nonthyroidal illness in dogs

OBJECTIVE: To determine the effects of endotoxin administration on thyroid function test results and serum tumor necrosis factor-alpha (TNF-alpha) activity in healthy dogs. ANIMALS: 6 healthy adult male dogs. PROCEDURES: Serum concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3'5'-triiodothyronine (rT3), free T4 (fT4), and endogenous canine thyroid stimulating hormone (TSH), and TNF-alpha activity were measured before (day-1; baseline), during (days 0 to 3), and after (days 4 to 24) IV administration of endotoxin every 12 hours for 84 hours. RESULTS: Compared with baseline values, serum T3 concentration decreased significantly, whereas rT3 concentration increased significantly 8 hours after initial endotoxin administration. Serum T4 concentration decreased significantly at 8 and 12 hours after initiating endotoxin administration. Serum T4 concentration returned to reference range limits, then decreased significantly on days 6 to 12 and 16 to 20. Serum fT4 concentration increased significantly at 12, 24, and 48 hours after cessation of endotoxin treatment, compared with baseline values. Serum rT3 concentration returned to reference range, then decreased significantly days 5 and 7 after stopping endotoxin treatment. Serum TNF-alpha activity was significantly increased only 4 hours after initial endotoxin treatment, compared with baseline activity. CONCLUSIONS AND CLINICAL RELEVANCE: Endotoxin administration modeled alterations in thyroid function test results found in dogs with spontaneous nonthyroidal illness syndrome. A decrease in serum T4 andT3 concentrations and increase in serum rT3 concentration indicate impaired secretion and metabolism of thyroid hormones. The persistent decrease in serum T4 concentration indicates that caution should be used in interpreting serum T4 concentrations after resolution of an illness in dogs.     

Effects of neutering on hormonal concentrations and energy requirements in male and female cats

OBJECTIVE: To determine whether changes in concentrations of hormones involved in glucose and fatty acid homeostasis are responsible for the increased probability that neutered cats will develop obesity and diabetes mellitus. ANIMALS: 10 male and 10 female weight-maintained adult cats. PROCEDURE: Results of glucose tolerance tests and concentrations of hormones and nonesterified fatty acids (NEFA) were examined before and 4, 8, and 16 weeks after neutering. RESULTS: Caloric requirements for weight maintenance were significantly decreased 8 and 16 weeks after neutering in females. Glucose concentrations during a glucose tolerance test did not change in neutered females or males. The area under the curve (AUC) for insulin was significantly higher in males, compared with females, before neutering. However, the AUC for insulin increased and was significantly higher 4 and 8 weeks after neutering in females. The AUC for insulin did not change in neutered male cats. Leptin concentrations did not change in females but increased significantly in males 8 and 16 weeks after neutering. Thyroxine concentrations did not change after neutering; however, free thyroxine concentration was significantly higher in females than males before neutering. Baseline concentrations of NEFA were significantly higher in female than male cats before but not after neutering. Suppression of NEFA concentrations after glucose administration decreased successively in male cats after neutering, suggesting decreased insulin sensitivity. CONCLUSIONS AND CLINICAL RELEVANCE: Changes in NEFA suppression, caloric intake, and leptin concentrations may be indicators of, and possible risk factors for, the development of obesity in cats after neutering.     

Reduced fasting periods increase intestinal permeability in chickens

Fasting of up to 24 hr has been shown to increase intestinal permeability (IP) in chickens. The aim of this study was to determine whether fasting duration of 4.5 and 9 hr increased IP and whether l ‐glutamine (a non‐essential amino acid) supplementation before fasting provided some protection of barrier function as shown in other species. Ross 308 male broilers (n = 96) were fed either a control diet or the same diet supplemented with 1% glutamine from d0 to d38 post‐hatch. On d37, the birds were assigned to single‐bird metabolism cages and were fasted for either 0, 4.5, 9 or 19.5 hr. This study design was 2 × 4 factorial with two levels of glutamine and four levels of fasting. Birds in the 0‐hr fasting group had free access to feed. All birds had ad libitum access to water. To measure IP on day 38, following their respective fasting periods, birds were administered two separate oral gavages of fluorescein isothiocyanate dextran (FITC‐d) followed by lactulose, mannitol and rhamnose (LMR) sugars, 60 min apart. Whole blood was collected from the jugular vein 90 min post‐LMR sugar gavage. FITC‐d and L/M/R ratios were measured by spectrophotometry and high‐performance ionic chromatography respectively. Lipopolysaccharide (LPS) endotoxins in plasma of the birds fed the control diet were also measured using chicken‐specific LPS antibody ELISA. Serum FITC‐d and plasma L/M and L/R ratios for 4.5, 9 and 19.5 hr were significantly (p < .05) higher compared to the non‐fasting group. However, IP was not different in the glutamine‐supplemented group (p > .05) compared to the control group. LPS concentrations measured by the ELISA were below the detectable range. We conclude that fasting periods of 4.5 and 9 hr increased IP compared to non‐fasted birds and dietary glutamine supplementation did not ameliorate changes in IP.     

Effect of fasting and refeeding on blood glutathione and lipid peroxide concentration of cockerels and pullets

Changes of reduced glutathione (GSH) and TBARS (thiobarbituric acid-reactive products of lipid peroxidation) concentrations and activity of gamma-glutamyltransferase (GGT, EC 2.3.2.2) in the blood of Lohman brown cockerels and pullets in response to 48 hour food deprivation and 24 hour refeeding were examined. The experiment was performed on 61-day-old chickens. Blood samples ware collected from the wing vein (v. brachialis) in heparinized tubes for three times: control sampling before fasting, then after 48 hour food deprivation and after refeeding for 24 hours. Blood GSH concentration after refeeding in cockerels was significantly higher compared with prefasting and fasting values. The concentration of GSH in female chickens was significantly lower after fasting as well as after refeeding compared with control values. In addition to that, in pullets GSH concentration in refeeding was higher than in fasting conditions. The level of TBARS in blood in female and male chickens after fasting and refeeding were significantly lower than the prefasting values. The GGT activity on cockerels after 48 hour food deprivation was significantly higher compared with control sampling and in chickens refeed for 24 hours, whereas in pullets significant difference was exhibit compared only with control values. Concentration of GSH in control sampling in cockerels compared with those in pullets was significantly lower. After 48 hours of fasting, the level of GSH was significantly higher in the cockerels than in the pullets. Results of TBARS concentration in the pullets were higher of control and fasting values than in the cockerels. The GGT activity of control sampling was significantly higher in male chicken. Lipid peroxidation in chickens of both sexes decreased with fasting, but prooxidative-antioxidative processes were more intensive in female chickens, probably because they were not reach sexual maturity.     

Long‐Term Effect of Deslorelin Implant on Ovarian Pre‐Antral Follicles and Uterine Histology in Female Rats

The objective of the present study was to investigate the inhibitory effects of long‐term deslorelin implant administration on the ovarian and uterine structures of female rats. A total of 16 non‐pregnant female rats were randomly assigned to two groups, each consisting of eight animals. Animals in the implant group (DESL) received subcutaneously (s.c.) a single deslorelin implant (4.7 mg), an analogue of GnRH, while no treatment was applied to the control group (CON). A single adult male rat was introduced into the cages of both the DESL and CON females after 6 weeks of implant administration. After 1 year of implant administration, all animals were killed and follicular structures and volumes of ovaries and uterus were examined using stereological methods. Stereological observations showed that the mean ovarian total volume of the DESL group (0.28 ± 0.07 cm3) was lower than that of the CON group (1.55 ± 0.23 cm3) (p < 0.001). On the other hand, the total number of pre‐antral follicles in the ovaries of DESL (555.32 ± 151.47) females were significantly lower than the control group (1162.96 ± 189.19) (p < 0.001). In the DESL group, the mean volumes of epithelium, endometrium, myometrium and total volume of the uterus were significantly (p < 0.001) lower than in the control groups. In conclusion, these findings indicate that the long‐term deslorelin implant (i) interferes with the normal cyclicity of female rats and (ii) affects the pre‐antral follicle population. Further studies will be required to determine the effects of long‐term deslorelin treatment on the pre‐antral follicle numbers and future fertility in other species.     

Androgen- and estrogen-dependent sex differences in host resistance to Strongyloides venezuelensis infection in Wistar rats

The effects of male and female sex hormones on the protective capacity of Wistar rats against infection with Strongyloides venezuelensis were investigated. Male rats were more susceptible than females in terms of worm recovery from the lungs. Orchidectomy of male animals significantly reduced the plasma testosterone concentration and increased host resistance to the migratory stages of S. venezuelensis larvae. In contrast, ovariectomy of female animals significantly decreased host resistance in association with a significant reduction of estrogen levels. To examine the direct effect of sex hormones, exogenous testosterone and estrogen were implanted into animals. Susceptibility significantly increased or decreased in ovariectomized females given testosterone or estrogen, respectively. These results suggest that male and female sex hormones are important in the down- and up-regulation of host resistance against S. venezuelensis in Wistar rats.     

Evaluation of complications and prognostic factors associated with administration of total parenteral nutrition in cats: 75 cases (1994-2001)

OBJECTIVE: To determine frequency and types of complications, prognostic factors, and primary diseases affecting clinical outcome associated with administration of total parenteral nutrition (TPN) in cats. DESIGN: Retrospective study. ANIMALS: 75 cats that received TPN for > or = 12 hours. PROCEDURE: Medical records were reviewed, and information was obtained on signalment, history, problems at initial evaluation, physical examination findings, weight and changes in weight while receiving TPN, duration in the hospital before initiation of TPN, the type of TPN catheter used, duration of TPN administration, and final diagnosis. Laboratory results obtained immediately prior to TPN and at 24 and 96 hours following initiation of TPN administration were compared. RESULTS: Reports of weight loss at initial evaluation, hyperglycemia at 24 hours, or diagnosis of chronic renal failure were significantly associated with increased mortality rate. Greater serum albumin concentrations prior to and at 96 hours following TPN administration were significantly associated with decreased mortality rate. Mechanical and septic complications were infrequent and not associated with increased mortality rate. Most cats had multiple diseases. The overall mortality rate was 52%; among 75 cats, 36 recovered, 23 were euthanatized, and 16 died as a result of their primary illness or complications associated with their illness. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated high mortality rate in cats maintained onTPN that had multiple concurrent diseases associated with a poor prognosis. Indicators of poor prognosis included a history of weight loss, hyperglycemia at 24 hours following TPN administration, hypoalbuminemia, and chronic renal failure.     

Effect of exogenous ACTH on serum corticosterone and cortisol concentrations in the Moluccan cockatoo (Cacatua moluccensis)

The effects of exogenous adrenocorticortrophic hormone (ACTH) on the serum corticosterone and cortisol concentrations were determined in 28 mature Moluccan cockatoos (Cacatua moluccensis), a representative of the psittacine species. Birds were randomly assigned to 4 groups (2 ACTH-treated groups and 2 saline-treated controls). Group I (10 cockatoos [5 males and 5 females] ) was given 15 IU of ACTH after blood samples (base line) were taken at 10:00 AM. Blood samples were taken again at 30 minutes and 2.5 hours after ACTH administration. Group II (10 cockatoos) was given similar treatment, but blood samples were taken at 1 and 4 hours after ACTH was administered. Groups III and IV (each of 4 birds) were given saline solution injections as controls. Blood samples were taken at 30 minutes and 2.5 hours after injection (group III) and at 1 and 4 hours after injection (group IV). All serum samples were analyzed for cortisol and corticosterone. Serum corticosterone concentration increased significantly (P less than 0.01) from base-line levels (26 ng/ml) to 108 ng/ml within 30 minutes after ACTH was administered. The high values were maintained for 3 hours and then decreased to 40 ng/ml at the end of 4 hours. Male birds seemed to respond to the ACTH treatment quickly and maintained increased concentration for a shorter period when compared with the responses seen in female birds. Serum cortisol values remained low throughout the experimental period. These results indicate that serum corticosterone was responsive to ACTH administration, but cortisol was not. In addition, there may be a difference in the responses between male and female members of the species.     

C-reactive protein concentrations in canine acute pancreatitis

Objective: To determine if C‐reactive protein (CRP) concentration is elevated in spontaneously occurring canine acute pancreatitis (AP), and to measure changes in CRP during the course of hospitalization. Design: Prospective study. Setting: Tufts University School of Veterinary Medicine Foster Hospital for Small Animals. Animals: Sixteen client‐owned dogs with AP and 16 healthy controls. Interventions: Blood samples were obtained from the AP group on the day of diagnosis (Day 1), and on Days 3 and 5, unless the dog died or was discharged from the hospital. Blood was obtained from the control dogs once. Measurements and main results: Serum CRP was measured using a commercial immunoassay for each dog with AP and for healthy controls. Day 1 CRP concentrations were significantly higher in the AP group (56.1±12.7 μg/mL) compared with controls (2.8±1.3 μg/mL; P<0.001). For the 7 dogs that had samples collected on all 3 days, the mean CRP concentrations decreased significantly (P=0.043) over the 5 days of measurement. Of the 16 dogs with AP, 14 were discharged from the hospital and 2 were euthanized. Conclusions: Serum CRP concentrations were elevated in this group of 16 dogs with spontaneously occurring AP. In the 7 dogs that had measurements on all 3 days, the mean CRP concentration decreased from the day of diagnosis to the measurement made 5 days later.     

Hepatobiliary transport of indocyanine green and sulfobromophthalein in fed and fasted horses

Fasting is associated with unconjugated hyperbilirubinemia in several species, including the horse. Studies in ponies showed that a 3-day fast decreased plasma clearance of bilirubin, cholic acid, and sulfobromophthalein (BSP). Since these organic anions are conjugated with different substrates, it is possible that observed differences in plasma clearance result from a general decrease in hepatic conjugating capacity during the animals' fasting. To test this hypothesis, the effects of a 3-day fast on plasma clearance of IV injected BSP (4.4 to 5.1 mg/kg), which is conjugated to glutathione, and indocyanine green (ICG; 0.8 to 1.1 mg/kg), which is not conjugated, were studied in 10 healthy horses and 2 ponies with diverted enterohepatic circulations (indwelling T tubes). Blood samples were obtained for 30 minutes after injection, and bile samples from ponies were obtained for 3 hours. Fasting increased plasma bilirubin concentration in all animals studied (from 1.03 +/- 0.337 mg/dl in control animals to 3.49 +/- 1.01 mg/dl in fasted animals). Kinetic values of ICG disappearance were determined from single exponential functions, and those for BSP were determined from both single and curvilinear (2-exponential) functions. Plasma clearance of BSP in fed horses (8.65 +/- 1.02 ml X min-1 X kg-1) was greater than clearance of ICG (3.54 +/- 0.67 ml X min-1 X kg-1), results similar to those reported in dogs, cats, rats, and persons. Fasting significantly decreased fractional plasma disappearance rate of both BSP (-36%) and ICG (-58%) and similarly reduced plasma clearance (BSP,-48%; ICG,-55%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Concentration-time interactions in hydrogen sulphide toxicity in rats.

Concentration-time interactions were investigated in young male and female Sprague-Dawley, Long Evans and Fischer-344 rats exposed to hydrogen sulphide for two, four or six hours. Higher concentrations caused more deaths, with no significant difference for duration of exposure. A significant sex effect was noted with 30% mortality in males and 20% in females, with no significant difference among strains. Changes in weight were significant: increasing with concentration, higher in males than in females, different among strains (Fischer-344 less than Sprague Dawley less than Long Evans), and affected by duration of exposure. Lethal concentration values (LC50 and LC10) were estimated, for the pooled data set (n = 456); the probit equation was Y = -5.74749 + 3.8259X where X is log10 dose of hydrogen sulphide in parts per million. The LC50/LC10 values were 644/298 parts per million (902/417 mg m-3) respectively. Individual probit analyses were also performed for strain, hours of exposure and sex. The LC50 and LC10 values for male, female and strain were not different. Significant differences were observed among LC50/LC10 values for hours of exposure (2 h = 587/549 parts per million, 822/769 mg m-3; 4 h = 501/422 parts per million, 701/591 mg m-3; 6 h = 335/299 parts per million, 469/491 mg m-3). There was no effect of spatial position in the exposure chamber on the distribution of mortality. All rats of all strains dying had severe pulmonary edema.     

Evaluation of the side-effects and thermal antinociceptive effects of intravenous hydromorphone in cats

Hydromorphone (H) may be an effective analgesic agent in cats, but fear of negative behavioral side‐effects associated with opioids is cited as a reason for avoiding this class of analgesics in cats. This study was designed to assess onset and duration of antinociception using an established feline thermal threshold model in cats, given an accepted clinical dose of 0.1 mg kg^?1 of H. In addition, cats were observed for changes in behavior and other side‐effects. Six adult cats from an established colony (four spayed females and two castrated males, 4.7–7.0 kg) received 0.1 mg kg^?1 H IV following establishment of baseline thermal threshold (TT) values. TT was tested at 15 minutes post‐injection, then at every 30–60 minutes for 12 hours. Side‐effects and behavior changes were recorded for 12 hours. Changes in TT over time were analyzed using a one‐way anova ; a p‐value <0.05 was considered significant. TT increased from a pre‐treatment value of (mean ± SD) 40.9 ± 1.65 °C to instrument cutout (55.5 °C) within 30 minutes for 5/6 cats. Mean TT was significantly elevated above baseline from 15 to 450 minutes after treatment. There was a significant increase in skin temperature from 15 to 300 minutes with peak increase of 1.55 °C at 135 minutes. Side‐effects included mydriasis (6/6) and nausea (4/6), characterized by licking, foaming, and gagging. Mydriasis occurred within 10–30 seconds of injection and persisted for 5–7 hours. Nausea was noted within 2 minutes of injection and persisted for 30–90 minutes; no vomiting occurred. Commonly observed behavioral changes included ventral tail curl (6/6 cats, onset 5–45 minutes, duration 4–5 hours) and euphoria (5/6 cats, onset <6 minutes for 4/6, duration 1–6 hours). 2/6 cats were profoundly sedate. Three cats showed signs of dysphoria with or without increased motor activity with variable onset and duration. Dysphoric behavior included staring, pacing, vocalizing, and sudden movements. 3/6 cats exhibited both euphoria and dysphoria at different times during the study. At no time were cats difficult to restrain or work with. Return to baseline behavior occurred 7–8.5 hours post‐injection. Mydriasis did not correlate closely with antinociception. Signs of sedation and euphoria corresponded with onset of antinociception, but not duration. Tail curl signs correlated with antinociception. In this model, H proved to be a rapid acting, potent, analgesic with a long (7.5 hours) duration of action. The most common behavioral changes noted were ventral tail curl, euphoria, and sedation. Mydriasis and nausea were noted as side‐effects.     

肉仔鸡生长过程中行为与产热的变化

研究肉仔鸡成长过程中行为变化对产热量的影响 ,将 2日龄肉仔鸡 36只分为自由摄食、 50 %摄食和绝食 3组进行观测。立位行为集中在明期 ,特别是摄食 30min前后 ,暗期几乎没有出现立体行为。 2日龄时 ,每天约有 70 0min是立位的 ,其后 ,随着日龄的增加而减少。在自由采食区 ,公雏比母雏摄食时间长。 50 %摄食区较自由采食区的摄食时间少。在绝食区 ,随着日龄的增加 ,公母的立位时间呈现减少倾向。 2 1日龄之前随着日龄的增加其摄食时间也增加 ,其后呈现相反倾向。产热 (HP ,kJ/kg0 75)与摄食时间有相同倾向。在 2 1日龄前公雏的HP比母雏低 ,2 1日龄后母雏比公雏低。 1天中各个区的HP活动规律是摄食后 1h内最高 ,暗期降低 ;限制摄食量后 ,HP降低 ,明期和暗期的HP差也随之减小     

Stability of hematologic analytes in monkey, rabbit, rat, and mouse blood stored at 4°C in EDTA using the ADVIA 120 hematology analyzer

Background: The time from sampling to analysis can be delayed when blood samples are shipped to distant reference laboratories or when analysis cannot be readily performed. Objective: The objective of this study was to evaluate the stability of hematologic analytes in blood samples from monkeys, rabbits, rats, and mice when samples were stored for up to 72 hours at 4°C. Methods: Blood samples from 30 monkeys, 15 rabbits, 20 rats, and 30 mice were collected into EDTA‐containing tubes and were initially analyzed within 1 hour of collection using the ADVIA 120 analyzer. The samples were then stored at 4°C and reanalyzed at 24, 48, and 72 hours after collection. Results: Significant (P<.0003) changes in hematologic analytes and calculations included increased HCT and MCV and decreased MCHC and cell hemoglobin concentration mean (CHCM) at 72 hours and increased MPV at 24 hours in monkeys; increased MCV at 72 hours and MPV at 48 hours and decreased monocyte count at 24 hours in rabbits; increased MCV and decreased MCHC, CHCM, and monocyte count at 24 hours in rats; increased MCV, red cell distribution width, and MPV and decreased MCHC, CHCM, and monocyte count at 24 hours in mice. Conclusions: Although most of the changes in the hematologic analytes in blood from monkeys, rabbits, rats, and mice when samples were stored at 4°C were analytically acceptable and clinically negligible, the best practice in measuring hematologic analytes in these animals is timely processing of blood samples, preferably within 1 hour after collection.