Facet joint geometry and intervertebral disk degeneration in the L5-S1 region of the vertebral column in German Shepherd dogs

OBJECTIVE: To evaluate the possible association between facet joint geometry and intervertebral disk degeneration in German Shepherd Dogs. ANIMALS: 25 German Shepherd Dogs and 11 control dogs of similar body weight and condition. PROCEDURE: Facet joint angles in the caudal portion of the lumbar region of the vertebral column (L5-S1) were measured by use of computed tomography, and the intervertebral discs were evaluated microscopically. The relationship between facet joint geometry and disk degeneration was evaluated by use of statistical methods. RESULTS: German Shepherd Dogs had significantly more facet joint tropism than control dogs, but an association with disk degeneration was not found. However, German Shepherd Dogs had a different facet joint conformation, with more sagittally oriented facet joints at L5-L6 and L6-L7 and a larger angle difference between the lumbar and lumbosacral facet joints, compared with control dogs. CONCLUSIONS AND CLINICAL RELEVANCE: A large difference between facet joint angles at L6-L7 and L7-S1 in German Shepherd Dogs may be associated with the frequent occurrence of lumbosacral disk degeneration in this breed.     

Plasma pharmacokinetics, pulmonary distribution, and in vitro activity of gamithromycin in foals

The objectives of this study were to determine the plasma and pulmonary disposition of gamithromycin in foals and to investigate the in vitro activity of the drug against Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) and Rhodococcus equi. A single dose of gamithromycin (6 mg/kg of body weight) was administered intramuscularly. Concentrations of gamithromycin in plasma, pulmonary epithelial lining fluid (PELF), bronchoalveolar lavage (BAL) cells, and blood neutrophils were determined using HPLC with tandem mass spectrometry detection. The minimum inhibitory concentration of gamithromycin required for growth inhibition of 90% of R. equi and S. zooepidemicus isolates (MIC(90)) was determined. Additionally, the activity of gamithromycin against intracellular R. equi was measured. Mean peak gamithromycin concentrations were significantly higher in blood neutrophils (8.35±1.77 μg/mL) and BAL cells (8.91±1.65 μg/mL) compared with PELF (2.15±2.78 μg/mL) and plasma (0.33±0.12 μg/mL). Mean terminal half-lives in neutrophils (78.6 h), BAL cells (70.3 h), and PELF (63.6 h) were significantly longer than those in plasma (39.1 h). The MIC(90) for S. zooepidemicus isolates was 0.125 μg/mL. The MIC of gamithromycin for macrolide-resistant R. equi isolates (MIC(90)=128 μg/mL) was significantly higher than that for macrolide-susceptible isolates (1.0 μg/mL). The activity of gamithromycin against intracellular R. equi was similar to that of azithromycin and erythromycin. Intramuscular administration of gamithromycin at a dosage of 6 mg/kg would maintain PELF concentrations above the MIC(90) for S. zooepidemicus and phagocytic cell concentrations above the MIC(90) for R. equi for approximately 7 days.     

Effect of dietary fat sources on systemic and intrauterine synthesis of prostaglandins during early pregnancy in gilts

The present experiment was conducted to determine the influence of dietary fatty acids C18:2n-6 and C18:3n-3 on the modulation of intrauterine synthesis of prostaglandin E2 (PGE2) and F2alpha (PGF2alpha) during early pregnancy in pigs. Prostaglandin E2 in uterine fluid has been previously reported to be associated with embryo survival and development. Thirty-two Yorkshire-Landrace nulliparous gilts were randomly allocated to four diets containing 5% supplemental fat. The four dietary treatments were: HT, hydrogenated tallow (26.5% C16:0 and 54.8% C18:0); SO, sunflower oil (61.3% C18:2n-6); LO, linseed oil (50.4% C18:3n-3); and SO(CLA), a mixture of sunflower oil and conjugated linoleic acids to provide 20% CLA. Treatments started 2 d after the first pubertal estrus (d -21) and lasted for 36 d (slaughter), which was 15 d after the second estrus (d 0; insemination). Fatty acids and PGE2 were measured in the peripheral blood plasma on d -19, d -7, d 0, and d 14. Fatty acids in endometrial tissues and PGE2 and PGF2alpha in the uterine fluid collected on d 15 were also measured. Concentrations of fatty acids in the plasma reflected the content of fatty acids in the diet as early as d -7. From d -7, PGE2 concentrations in the plasma were higher in gilts fed SO compared with HT (P < 0.05). Plasma PGE2 concentrations were lower (P < 0.01) on d 14 in gilts fed LO compared with HT. Total PGF2alpha contents in the uterine fluid of gilts fed LO were more than 70% lower (P < 0.05) than for the HT group. A similar trend was observed for total PGE2 content and for the ratio PGF2alpha:PGE2, but the effect (LO vs HT) was less marked (P < 0.07 and P < 0.10, respectively). There was no effect of SO or SO(CLA) on total PGE2 contents in the uterine fluid. Dietary enrichment in C18:2n-6 and/or C18:3n-3 for early pregnant gilts can influence fatty acids in plasma and endometrial tissue and can modulate circulatory and intrauterine prostaglandins.     

Evaluation of low-molecular-weight heparin for the prevention of equine laminitis after colic surgery

Objectives – The aim of this study is to describe the prevalence of postoperative laminitis in colic cases and to determine if low-molecular-weight heparin (LMWH) is effective in preventing this complication.
Design – Retrospective clinical study.
Animals – Client-owned horses.
Interventions – SC administration of enoxaparin during the postoperative period.
Measurements and Main Results – Medical records of 360 horses undergoing surgery for colic and surviving at least 3 days were evaluated. Fifty-six horses admitted before 1995 did not receive LMWH (control group) and 304 admitted after 1995 received LMWH as a prophylaxis for laminitis (treatment group). Three grades of severity were defined for laminitis. Prevalence and severity of laminitis were compared between the 2 groups. Several parameters recorded on admission (sex, age, breed, site and nature of the disease, heart rate, PCV, gravity score, and shock score) and the administration of LMWH were tested as risk factors in the development of laminitis in a logistic regression procedure. Prevalence and grade of laminitis were significantly lower in the treatment group. Only the absence of LMWH was recognized as a significant risk factor in the logistic regression model.
Conclusions – The administration of LMWH appears to be effective in the prophylaxis of laminitis following colic surgery and may be useful in the postoperative management of these horses.     

Influence of litter size on metabolic status and reproductive axis in primiparous sows

This study on primiparous sows was designed to 1) determine the impact of nursing a large litter on LH secretion and follicular development, and 2) investigate the metabolic adaptations by which milk yield increases with litter size. At farrowing, crossbred, primiparous sows were assigned to 1 of 3 experimental groups differing in litter size and feed allowance. Sows with 13 or 14 piglets (13AL, n = 7) were fed ad libitum. Sows with 7 piglets were fed ad libitum (7AL, n = 6) or were feed-restricted (7R, n = 8). The restriction was based on the estimated energy deficiency for the 13AL sows. On d 9 +/- 1 of lactation, a jugular catheter was surgically implanted. Serial blood samplings and glucose tolerance tests were performed in mid- and late lactation. Sows were slaughtered 3 d after weaning, and ovarian characteristics were recorded. During lactation, the 7AL sows lost no or little body reserves, and their estimated energy balance was near zero. The 13AL and 7R sows exhibited similar negative energy balances and similar losses of backfat and estimated lipid content. Litter growth rate was greater (P < 0.05) in the 13AL than in the 7AL and 7R groups. After weaning, the volume of the largest 14 follicles was smaller (P < 0.05) in sows nursing 13 or 14 piglets than in sows with 7 piglets. Plasma concentrations of LH and LH pulse frequency did not differ between groups (P > 0.1). The longer glucose half-life on d 16 than on d 27 of lactation (22.5 vs. 18.8 min; P < 0.05) indicated a lower glucose tolerance in mid- than in late lactation. The area under the insulin curve was greater in the 7AL than in the 13AL sows (P = 0.08) and intermediate in the 7R group, with no differences in glucose profiles. This led to the suggestion that the 7AL sows were more resistant to insulin than the 13AL sows. In all groups of sows, follicular development after weaning was correlated with LH secretion in midlactation. Active follicular development was associated with prolonged secretion of insulin in response to glucose challenge. Our results show that besides litter size, a sow's metabolic status in lactation influences follicular maturation after weaning and also indicate that the metabolic adaptations by which primiparous sows nursing large litters increase litter growth rate and body reserve mobilization do not involve an accentuated peripheral insulin resistance.     

Adaptations of glucose metabolism in multiparous sows: effects of pregnancy and feeding level

This experiment was undertaken to determine whether pregnancy affects glucose metabolism and insulin sensitivity in sows fed at different levels. Four replicates of six multiparous Large White sows were involved. In each replicate, four sows were inseminated on the first postweaning estrus (pregnant group) and the two remaining were kept nonpregnant. Half of the sows of each group were fed 2.5 kg/d (low level) and the others 4 kg/d (high level) of the same standard pregnancy diet. Jugular catheters were implanted 2 to 3 d after estrus. Plasma concentrations of glucose, insulin, and FFA were determined before and during the 4 h following the morning meal at 10, 30, 59, 87, 93, 101, and 110 d of gestation and at equivalent periods for the nonpregnant sows. Intravenous glucose tolerance tests were performed at 33, 71, 85, 96, and 108 d by i.v. injection of 0.5 g glucose/kg BW. Compared with the glycemia before the meal, all the sows showed hyperglycemia 30 min after the initiation of the meal and hypoglycemia thereafter, with a minimum reached at approximately 75 min. Insulinemia increased from 20 min after food access, reached a maximum at 40 min, and returned to the basal level after 180 min. The higher feeding level increased plasma insulin and lowered plasma glucose levels. Glycemia and insulinemia profiles changed from 87 d onward in the pregnant sows. The peak of glucose induced by the meal was higher, and the subsequent period of hypoglycemia almost disappeared. The area under the insulin curve was unchanged, but insulin secretion was delayed. The glucose tolerance tests showed that between d 85 and 108 the half-life of injected glucose increased and insulin secretion was delayed in the pregnant sows. Compared to the following stages, plasma FFA were high before and after the meal at 10 d, which most likely was a residual effect from the previous gestation/lactation cycle. They were lower from 30 to 101 d in the pregnant and nonpregnant sows. At 110 d, fasting FFA were high again in the pregnant sows only, very likely in relation to the preparation for lactation. This experiment showed that insulin sensitivity decreases after 85 d of pregnancy in multiparous sows.     

Effects of nutrient supply and dietary bulk on O2 uptake and nutrient net fluxes across rumen,mesenteric- and portal-drained viscera in ewes

We assessed the effects of nutrient supply and dietary bulk, both increasing with hay intake, on O2 uptake and nutrient net fluxes across the portal-(PDV) and mesenteric- (MDV) drained viscera, and the rumen in adult ewes. Four ewes, fitted with a ruminal cannula, with catheters in the mesenteric artery, the portal, mesenteric and right ruminal veins, and with a blood flow probe around the right ruminal artery, were used in a 4 x 4 Latin square design. Treatments consisted of 500 g DM/d hay (LL, low bulk and low nutrient supply), 500 g DM/d hay + infused nutrients (LH, low bulk and high nutrient supply), 750 g DM/d hay + infused nutrients (MH, medium bulk and high nutrient supply), and 1,000 g DM/d hay (HH, high bulk and high nutrient supply). Infused nutrients consisted of volatile fatty acids (VFA) and casein dissolved in salts and infused continuously in the rumen to provide the same amount of metabolizable energy (7.6 MJ/d) and digestible protein (63 g/d) for LH, MH, and HH. Both increases in bulk and nutrient supply increased O2 uptake in the MDV and PDV. Dietary bulk stimulated mainly blood flow, whereas nutrient supply stimulated mainly O2 extraction rate. The O2 uptake by the rumen was not significantly affected by hay intake, although blood flow increased due to nutrient supply. Increase in hay intake had no effects on portal net release of lactate and net uptake of glucose but increased VFA, 3-D-hydroxybutyrate, ammonia, and amino acids (AA) net release and urea net uptake across PDV. The increase in portal nutrient net fluxes with hay intake was entirely related to the increase of nutrient supply for VFA, 3-D-hydroxybutyrate, ammonia, and urea, irrespective of the amount of casein infused for AA. Dietary bulk had no effect on total energy net release in the portal vein. We conclude that despite the increase in portal O2 uptake, increasing dietary bulk had no significant impact on portal recovery of energy. In ruminal tissues, which were the main site of energy absorption, O2 uptake appeared low and was not sensitive to dietary manipulation. In contrast, in mesenteric tissues, which contribute poorly to energy absorption with forage diets, O2 uptake appeared high and very sensitive to dietary manipulation.