Effect of dietary protein content and tryptophan supplementation on dominance aggression, territorial aggression, and hyperactivity in dogs

OBJECTIVE: To evaluate the effect of high- and low-protein diets with or without tryptophan supplementation on behavior of dogs with dominance aggression, territorial aggression, and hyperactivity. DESIGN: Prospective crossover study. ANIMALS: 11 dogs with dominance aggression, 11 dogs with territorial aggression, and 11 dogs with hyperactivity. PROCEDURE: In each group, 4 diets were fed for 1 weeks each in random order with a transition period of not < 3 days between each diet. Two diets had low protein content (approximately 18%), and 2 diets had high protein content (approximately 30%). Two of the diets (1 low-protein and 1 high-protein) were supplemented with tryptophan. Owners scored their dog's behavior daily by use of customized behavioral score sheets. Mean weekly values of 5 behavioral measures and serum concentrations of serotonin and tryptophan were determined at the end of each dietary period. RESULTS: For dominance aggression, behavioral scores were highest in dogs fed unsupplemented high-protein rations. For territorial aggression, [corrected] tryptophan-supplemented low-protein diets were associated with significantly lower behavioral scores than low-protein diets without tryptophan supplements. CONCLUSIONS AND CLINICAL RELEVANCE: For dogs with dominance aggression, the addition of tryptophan to high-protein diets or change to a low-protein diet may reduce aggression. For dogs with territorial aggression, tryptophan supplementation of a low-protein diet may be helpful in reducing aggression.     

Determination of homovanillic acid, 5-hydroxyindoleacetic acid and pressure in the cerebrospinal fluid of Collie dogs following administration of ivermectin

Twelve adult Collie dogs were studied to determine the effects of ivermectin on neurotransmitter metabolites released from the brain into the cerebrospinal fluid (CSF) and on CSF pressure. Ten of the 12 Collies were given ivermectin orally at a concentration of 200 g/kg body weight. Three of these 10 Collies showed clinical signs of ivermectin-induced toxicosis which progressed into a state of unresponsive recumbency in 2 dogs.Cerebrospinal fluid pressures and neurotransmitter metabolite concentrations in cisterna magna CSF were analysed 49 to 50 hours after administration of ivermectin in 6 of the 10 treated dogs, and in the 2 untreated control Collies. Cerebrospinal fluid pressures were within normal limits in all dogs. However, compared to the CSF concentrations in the 2 untreated and 3 non-reactive Collies, the 2 ivermectin-reactive Collies still in recumbency had elevated CSF concentrations of homovanillic acid (HVA), a metabolite of dopamine, and 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin. These findings suggest an association between altered neurotransmission and severe ivermectin-induced neurological abnormalities. No evidence of elevated intracranial pressure was found.     

Total protein, albumin quota, and electrophoretic patterns in cerebrospinal fluid of dogs with central nervous system disorders

Cerebrospinal fluid was analyzed for total protein, albumin quota, and electrophoretic patterns of albumin and alpha-, beta-, and gamma-globulins in 10 healthy dogs and 35 dogs with CNS disorders. Values obtained in healthy dogs were used to establish control data. Samples also were collected from dogs with neurologic diseases that were classified according to clinical and pathologic diagnosis as inflammation, neoplasm, and spinal cord compression. The albumin quota and total CSF albumin values were used as indicators of blood-brain barrier disturbance. Four patterns were observed on agarose electrophoresis that included intrathecal immunoglobulin production, intrathecal immunoglobulin production combined with blood-brain barrier disturbance, blood-brain barrier disturbance, and unaltered CSF. These patterns correlated with the observed clinical and pathologic conditions. Seemingly, agarose electrophoresis of CSF is a simple and reliable technique that aids in the diagnosis of CNS disorders of dogs.     

A rostrocaudal gradient for neurotransmitter metabolites and a caudorostral gradient for protein in canine cerebrospinal fluid

Neurotransmitter metabolites (dihydroxyphenylacetic acid [DOPAC], homovanillic acid [HVA], and 5-hydroxyindoleacetic acid [5-HIAA]) in CSF of 10 healthy dogs were evaluated with reverse-phase high-pressure liquid chromatography and electrochemical detection. Neurotransmitter metabolite concentrations determined in CSF collected from the cisterna magna were compared with those values in CSF collected from the lumbar dorsal subarachnoid space. Amounts of DOPAC (P = 0.0444), HVA (P = 0.0001), and 5-HIAA (P = 0.0316) were significantly lower in lumbar spinal fluid compared with those values in the cervical spinal fluid. Metabolite concentrations in cervical and lumbar CSF were: DOPAC = 2.81 +/- 0.73 ng/ml of CSF and 1.28 +/- 0.57 ng/ml; HVA = 98.29 +/- 12.42 ng/ml and 4.68 +/- 1.61 ng/ml; and 5-HIAA = 46.29 +/- 8.17 ng/ml and 36.96 +/- 4.07 ng/ml, respectively. Cytologic evaluations of cervical and lumbar CSF revealed a similar concentration of 3 +/- 1 WBC/microliters in both fluids. A significant (P = 0.0002) difference in protein concentration between the 2 regions was observed, with 16.1 +/- 1.8 mg of protein/dl in the cervical CSF and 27.2 +/- 2.3 mg of protein/dl in the lumbar CSF. Between the cisterna magna and lumbar dorsal subarachnoid space of dogs, a rostrocaudal gradient existed for neurotransmitter metabolites, and a caudorostral gradient existed for protein.     

Nitrogen metabolism and growth performance of gilts fed standard corn-soybean meal diets or low-crude protein,amino acid-supplemented diets

Two experiments were conducted to determine the CP concentration below which N retention and growth performance are reduced when low-protein, amino acid-supplemented, corn-soybean meal diets are fed. In a N balance trial (Exp. 1), 12 gilts (initial weight 41 kg) were fitted with urinary catheters and fed six different diets during three 7-d periods in an incomplete block design. The diets were: 1) 18% CP; 2) 14% CP + AA, 3) 16% CP; 4) 12% CP + AA; 5) 14% CP; and 6) 10% CP + AA. Amino acids (lysine, threonine, tryptophan, and methionine) were supplemented such that the concentrations in the low-protein diets were equal to those in their standard (4% CP higher) counterparts. Nitrogen retention (g/d) decreased (P < 0.01) as CP decreased, in both standard (27.10, 24.53, and 20.99) and low-protein (21.51, 19.18, and 15.83) diets, but was lower (P < 0.01) in low-protein diets. There were no differences among treatments (P > 0.05) in biological value (68.2% standard vs 71.0% low-protein). In a growth performance trial (Exp. 2), 36 gilts (initial weight 19.5 kg) were penned individually and fed one of six diets for 35 d in a randomized complete block design. Dietary treatments were a 16% CP standard diet and low-protein diets formulated to contain 15, 14, 13, 12, and 11% CP supplemented with crystalline lysine, tryptophan, threonine, and methionine to equal the total concentrations in the standard diet. Protein concentration affected (P < or = 0.05) ADG, ADFI, feed efficiency, fat-free lean gain, longissimus muscle area, plasma urea, and plasma concentrations of most essential AA. For most of these traits, the major difference was poor performance of pigs fed the 11% CP diet. Thus, in Exp. 1, at AA concentrations from deficient to excess, low-protein, amino acid-supplemented diets failed to produce the same N retention as the equivalent corn-soybean meal diets. However in Exp. 2, the same performance was obtained with 16, 15, 14, 13, and 12% CP. Based on these data, we suggest that N balance is more sensitive than growth to amino acid adequacy andthat other AA (e.g., isoleucine and valine) may limit growth performance when the protein concentration is reduced by more than four percentage units.     

Cytologic interpretation of canine cerebrospinal fluid samples with low total nucleated cell concentration,with and without blood contamination

Background: Cerebrospinal fluid (CSF) is potentially altered by iatrogenic blood contamination at the time of sampling due to the addition of blood‐associated leukocytes and protein. Objectives: The objective of this study was to assess whether protein concentration, neutrophil percentage, and the presence of activated macrophages, reactive lymphocytes, or eosinophils in CSF samples with low total nucleated cell concentration (TNCC) are affected by blood contamination or associated with central nervous system (CNS) disease. Methods: Case records from the Royal Veterinary College Diagnostic Laboratory were searched retrospectively for dogs with CSF having ≤5 TNCC/μL. TNCC, RBC, and protein concentrations; neutrophil percentage; and the presence of activated macrophages, reactive lymphocytes, and eosinophils were recorded. Results of magnetic resonance imaging (MRI) also were recorded as a marker of CNS disease. Results: Of 906 cases evaluated, 106 (12%) had blood contamination (>500 RBCs/μL) in CSF. Protein concentration and neutrophil percentage were significantly higher and the presence of eosinophils was more likely in blood contaminated vs noncontaminated samples. Non‐blood‐contaminated samples with activated macrophages or reactive lymphocytes had higher protein concentrations and neutrophil percentages, and those with activated macrophages were more likely to have a positive finding on MRI. Conclusions: Protein concentration, neutrophil percentage, and the presence of eosinophils are significantly affected by blood contamination in canine CSF having low TNCC. Activated macrophages and reactive lymphocytes are not affected by blood contamination, however, and may be useful in identifying dogs with CNS abnormalities.     

Effects of intravenous tryptophan infusion on thermoregulation in steers exposed to acute heat stress

This study was conducted to investigate the effect of tryptophan (TRP) supply on the thermoregulatory responses via brain serotonin (5‐HT) in cattle. In period 1, 12 Holstein steers were kept under a constant room temperature (22°C) and were administered the intravenous (i.v.) infusion of saline or TRP (38.5 mg/kg/2 h). Changes in rectal temperature (RT), 5‐HT concentration in the cerebrospinal fluid (CSF), and other factors involved in thermoregulation were measured. In period 2, the steers received the same treatments as in period 1; however, the room temperature was elevated from 22°C to 33°C during i.v. infusion and maintained at 33°C for 3 h. 5‐HT concentration in CSF increased following TRP infusion in both periods, and RT significantly decreased following TRP infusion only in period 2. The effect of TRP on respiration rate and plasma prolactin and total triiodothyronine concentrations was not significant. These results suggest that increase in TRP supply can attenuate increase in RT in response to acute heat stress through the increase in brain 5‐HT, followed by presumable increase in evaporative heat loss from the skin surface in cattle. It is possible that the increase in peripheral blood TRP metabolites could also participate in the hypothermic effect of TRP.     

Beta-2-microglobulin levels in the cerebrospinal fluid of normal dogs and dogs with neurological disease

BACKGROUND: Cerebrospinal fluid (CSF) analysis is the basis for establishing a diagnosis of central nervous system (CNS) inflammation. However, the information provided by routine CSF analysis is limited. Determination of CSF beta-2-microglobulin (beta2m) concentration has been used diagnostically in humans to identify inflammatory CNS disease; we hypothesized that it may have similar value in dogs. OBJECTIVES: The objective of this study was to measure (beta2m concentration in the CSF of clinically healthy dogs and compare the values to those observed in dogs with inflammatory CNS disease and intervertebral disc disease (IVDD). METHODS: CSF was collected from 10 clinically healthy laboratory dogs and 11 dogs each with inflammatory CNS disease and IVDD. Routine CSF analysis was performed, and (beta2m concentration was measured by ELISA. CSF (beta2m concentration and CSF:serum (beta2m ratio were compared between groups by ANOVA. Linear relationships between CSF total nucleated cell count (TNCC), RBC count, total protein concentration, and (beta2m concentration were assessed by regression analysis. RESULTS: The mean (+/- SD) CSF (beta2m concentration in clinically healthy dogs was 0.36 (+/- 0.05 microg/mL (cisternal) and 0.40 (+/- 0.07 microg/mL (lumbar). Median CSF (beta2m concentration in dogs with IVDD (0.46 microg/mL) and inflammatory CNS disease (0.85 microg/mL) differed from that of controls (0.36 microg/mL; P=.002). The concentration also differed between the 2 disease groups (P=.01). Five dogs with inflammatory CNS disease had CSF:serum (beta2m ratios >1. A correlation was identified between TNCC and (beta2m concentration (r=0.69, P=.0003). CONCLUSIONS: CSF (beta2m concentration is higher in dogs with IVDD and inflammatory CNS disease, with highest values seen with inflammatory disease. This may be attributed in part to the correlation between CSF (beta2m concentration and TNCC, but also may reflect intrathecal immune activation.     

Inhibitory and excitatory neurotransmitters in the cerebrospinal fluid of epileptic dogs

OBJECTIVE: To determine concentrations of excitatory and inhibitory amino acids in CSF of a large number of dogs with idiopathic epilepsy or genetic epilepsy and to evaluate changes in CSF amino acid concentration with regard to drug treatment and sex. ANIMALS: 35 Labrador Retrievers with genetic epilepsy (20 male and 15 female), 94 non-Labrador Retrievers with idiopathic epilepsy (71 male and 23 female), and 20 control dogs (10 male and 10 female). PROCEDURE: Collection of CSF was performed > 72 hours after the occurrence of seizures. Cerebrospinal fluid concentrations of gamma-aminobutyric acid (GABA), glutamate (GLU), aspartate (ASP), serine, and glycine were determined by use of high performance liquid chromatography with electrochemical detection. RESULTS: CSF concentrations of GABA and GLU were significantly lower in Labrador Retrievers with genetic epilepsy (LR-group dogs) than in control-group dogs or in non-Labrador Retrievers with idiopathic epilepsy (non-LR-group dogs). The GLU-to-GABA ratio was significantly higher in LR-group dogs than in non-LR-group dogs. CSF concentrations of GLU and ASP were significantly lower when all dogs with epilepsy (non-LR- and LR-group dogs combined) were compared with control-group dogs. CONCLUSIONS AND CLINICAL RELEVANCE: A decrease in CSF concentrations of GABA appears to play a role in the pathogenesis of genetically determined epilepsy in Labrador Retrievers. However, this decrease in CSF concentrations of GABA may also be a consequence of seizure activity. The GLU-to-GABA ratio may prove to be a useful indicator of genetic epilepsy in Labrador Retrievers.     

Physiological responses of dietary tryptophan fed Labeo rohita to temperature and salinity stress

Two experiments were conducted to elucidate the possible effects of dietary L‐tryptophan (TRP) in Labeo rohita based on growth performance and physio‐biochemical responses. In the experiment I, a 60‐day feeding trial was carried out to elucidate the effects of dietary TRP enrichment on growth performance and physio‐biochemical responses. In the experiment II, the TRP pre‐fed L. rohita, from experiment I, was exposed to temperature and salinity stress to evaluate stress‐mitigating efficacy of TRP. In L. rohita, dietary supplementation of TRP showed significant effect on weight gain percentage and feed conversion ratio but not on blood glucose. A significant increase in RNA content and RNA/DNA ratio upon TRP supplementation was observed and was positively correlated with growth performance. The results of experiment II indicated that weight gain percentage, serum T3 and T4 levels were significantly reduced in groups that were exposed to temperature and salinity stress and fed diets without TRP supplementation. However, dietary supplementation of TRP significantly augmented weight gain percentage in stress‐exposed groups. Tryptophan supplementation helped in bringing back T3 and T4 levels comparable with control. A significant increase in superoxide dismutase, catalase, Adenosine triphosphatase, blood glucose and serum cortisol was observed in temperature‐ and salinity‐exposed groups fed without TRP‐supplemented diets. However, TRP supplementation was found to be effective in restoring the above parameters. The results of these experiments suggest that dietary TRP supplementation augments growth, lowers energy demand and helps in mitigating thermal and salinity stress in L. rohita.     

Impact of dietary tryptophan and behavioral type on behavior, plasma cortisol, and brain metabolites of young pigs.

The behavioral reactivity in an "open-field" test and plasma cortisol levels were studied in 72 pigs from 12 litters fed for 3 wk one of three diets with different levels of tryptophan: deficient (.14%), adequate (.23%), or excess (.32%). "Open-field" tests were performed three times: 5 d (day W + 5), 23 d (day W + 23) and 45 d (day W + 45) after weaning. The exploration time and the number of grunts provided an adequate measure of the individual emotional reactivity at day W + 5. Significant correlations were obtained between exploration time and the number of grunts at each time (r = -.83 at day W + 5; r = -.46 at day W + 23; r = -.71 at day W + 45). The distinction between animals remained (P less than .05) in terms of exploration time at both 23 and 45 d after weaning. At day W + 23, exploration time was lower in the group fed the adequate diet than in the two other groups. This effect was maintained subsequently after feeding all pigs the same adequate diet (day W + 45). In 36 pigs slaughtered at day W + 23, brain TRP concentration was higher with the excess dietary TRP than with deficient or adequate levels. Conversely, other plasma amino acids (particularly threonine) accumulated only in the brains of pigs fed the deficient diet. Plasma cortisol level assayed at weaning (W) and 2 wk later increased with age and was higher in 16-h fasted (day W + 15) than in 3-h fasted (day W + 17) pigs. Correlations were observed within litters in the fasting state, between the cortisol level and behavioral traits measured at day W + 23 (r = .70 for number of grunts, r = -.60 for exploration time). Dietary TRP did not affect the plasma cortisol level irrespective of the nutritional state after weaning. However, an interaction was noted between plasma cortisol and TRP status (P less than .05). Although dietary TRP induced large variations in brain amino acids and 5-hydroxyindole concentrations, changes in behavioral and cortisol responses were relatively minor.     

Excess dietary tryptophan mitigates aflatoxicosis in growing quails

A biological assay was carried out to evaluate the impact of dietary tryptophan (TRP) in aflatoxin B₁‐contaminated diets (AFB₁‐D) on performance, blood parameters, immunity, meat quality and microbial populations of intestine in Japanese quails. Six experimental diets were formulated to include two levels of dietary TRP; 2.9 (moderate high: MH‐TRP) and 4.9 g/kg (excess: Ex‐TRP); and three levels of AFB₁ (0.0, 2.5, and 5.0 mg/kg). Each experimental diet was fed to the one of the six groups of birds from 7 to 35 days of age in a completely randomized design with 2 × 3 factorial arrangement. Decrease in feed intake, body weight gain and gain:feed in birds fed 5.0 mg/kg AFB₁‐D was restored to the control level by 4.9 g TRP/kg of the diet. The hepatic enzymes in blood were elevated in quails fed on AFB₁‐D but attenuated by 4.9 g TRP/kg of the diet (Ex‐TRP; p ≤ .01). High serum uric acid in birds challenged with AFB₁ significantly decreased by Ex‐TRP (p ≤ .01). The skin thickness to 2,4‐dinitro‐1‐chlorobenzene challenge suppressed by AFB₁ but increased by Ex‐TRP diet (p ≤ .02). The AFB₁ increased the malondialdehyde in meat, whereas TRP efficiently diminished malondialdehyde production (p ≤ .01). The greatest drip loss and pH in meat were observed in the birds fed 5.0 mg/kg AFB₁‐D but Ex‐TRP augmented the adverse effects of AFB₁ (p ≤ .01). The Ex‐TRP reduced the total microbial and Escherichia coli counts (p ≤ .01). The adverse effect of AFB₁ on ileal Lactic acid bacteria was completely prevented by Ex‐TRP (p ≤ .03). This study showed that tryptophan supplementation could be considered as a powerful nutritional tool to ameliorate the adverse effects of AFB₁ in growing quails.     

Use of anti-coronavirus antibody testing of cerebrospinal fluid for diagnosis of feline infectious peritonitis involving the central nervous system in cats

OBJECTIVE: To assess the use of measuring anti-coronavirus IgG in CSF for the diagnosis of feline infectious peritonitis (FIP) involving the CNS in cats. DESIGN: Prospective study. SAMPLE POPULATION: CSF and serum samples from 67 cats. PROCEDURES: CSF and serum samples were allocated into 4 groups: cats with FIP involving the CNS (n = 10), cats with FIP not involving the CNS (13), cats with CNS disorders caused by diseases other than FIP (29), and cats with diseases other than FIP and not involving the CNS (15). Cerebrospinal fluid was evaluated for concentrations of erythrocytes, leukocytes, and total protein. Anti-coronavirus IgG was measured in CSF and serum by indirect immunofluorescence assay. RESULTS: CSF IgG (range of titers, 1:32 to 1:4,096) was detected in 12 cats, including 6 cats with neurologic manifestation of FIP, 4 cats with FIP not involving the CNS, and 2 cats with brain tumors. Cerebrospinal fluid IgG was detected only in cats with correspondingly high serum IgG titers (range, 1:4,096 to 1:16,384) and was positively correlated with serum IgG titers (r = 0.652; P < 0.01), but not with any other CSF parameter. Blood contamination of CSF resulted in < or = 333 erythrocytes/microL in cats with CSF IgG. CONCLUSIONS AND CLINICAL RELEVANCE: The correlation between serum and CSF IgG and the fact that CSF IgG was detected only in strongly seropositive cats suggested that CSF anti-coronavirus IgG was derived from blood. Measurement of anti-coronavirus IgG in CSF was of equivocal clinical use.     

A possible role of central serotonin in L‐tryptophan‐induced GH secretion in cattle

To clarify the role of serotonin (5‐HT) in the regulatory mechanism of L‐tryptophan (TRP)‐induced growth hormone (GH) secretion in cattle, changes in 5‐HT concentrations in the cerebrospinal fluid (CSF) in the third ventricle (3V) and GH in plasma before and after the peripheral infusion of TRP were determined simultaneously. The direct effect of TRP on GH release from the dispersed anterior pituitary cells was also assessed. A chronic cannula was placed in 3V by stereotaxic surgery, then CSF and blood were withdrawn under physiological conditions. TRP (38.5 mg/kg BW) was infused through an intravenous catheter from 12.00 to 14.00 hours and CSF and blood sampling were performed from 11.00 to 18.00 hours at 1‐h intervals. The concentration of 5‐HT in CSF was determined by high‐performance liquid chromatography with electrochemical detection. GH, melatonin (MEL), and cortisol (CORT) concentrations were measured by radio‐immunoassay and enzyme‐immunoassay. Concentrations of 5‐HT were increased by TRP infusion. The TRP infusion significantly increased GH release. On the other hand, TRP did not stimulate GH release from the bovine pituitary cells. MEL and CORT concentrations were not altered by TRP infusion. These results suggest that TRP induced GH release via the activation of serotonergic neurons in cattle.     

Growth performance, diet apparent digestibility, and plasma metabolite concentrations of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding level

Two experiments, each with 36 barrows with high-lean-gain potential, were conducted to evaluate apparent nutrient digestibilities and performance and plasma metabolites of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets. The low-protein diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis or by feeding 90 or 80% of ad libitum intake. Pigs were fed for 55 d. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis or by feeding 80% of the ad libitum intake. Pigs were fed for 27 d. Pigs fed the CONTROL diet had greater (P < 0.05) ADG and feed efficiency (G/F) than pigs fed the IDEAL (Exp. 1 and 2) and AACON diets (Exp. 2). As the level of feed intake decreased, ADG decreased (P < 0.05), but G/F tended to improve (P < 0.10) for pigs fed 90% of ad libitum in Exp. 1 and for pigs fed 80% of ad libitum in Exp. 2. In Exp. 1, the apparent total tract digestibilities of DM and energy were greater (P < 0.01) for pigs fed the IDEAL diet than for pigs fed the CONTROL diet. In Exp. 2, the apparent total tract digestibility of protein was greatest in pigs fed the CONTROL diet (P < 0.05) and was greater (P < 0.05) in pigs fed the AACON diet than in pigs fed the IDEAL diet. Plasma urea concentrations were lower in pigs fed the IDEAL diet than in pigs fed the CONTROL diet, regardless of feeding level. For pigs fed the CONTROL diet, plasma urea concentrations were lower when feed intake was 80% of ad libitum (diet level, P < 0.01). In summary, pigs fed the IDEAL and the AACON diets gained less and had lower plasma urea concentrations than pigs fed the CONTROL diet. Based on these data, it seems that the growth potential of pigs fed the IDEAL and AACON diets may have been limited by a deficiency of lysine, threonine, and(or) tryptophan and that the amino acid pattern(s) used was not ideal for these pigs.     

Transient leakage across the blood-cerebrospinal fluid barrier after intrathecal metrizamide administration to dogs

Cerebrospinal fluid samples from 9 dogs given 84 mg of metrizamide/kg of body weight intrathecally were collected at intervals from 3 hours to 30 days after treatment and were compared with CSF samples collected before metrizamide treatment (base line) and with samples taken at similar intervals from 2 nontreated control dogs. Increased CSF albumin (mean 19.2 mg/dl) and immunoglobulin (Ig) G (mean 5.91 mg/dl) concentrations occurred 1 day after myelography, compared with base-line concentrations (6.15 and 1.24 mg/dl, respectively) and with concentrations from controls. Immunoglobulin M and IgA concentrations also were increased in some of these samples. However, immediately after myelography (3 hours after treatment) CSF albumin and IgG concentrations were comparable with those of controls, and these values returned to base line within 5 days of myelography and remained so for 30 days. A high correlation between albumin and IgG concentrations of individual CSF samples indicated the likelihood that leakage across the blood-CSF barrier was the origin of the increased values. A transient increase in CSF leukocytes, consisting of mononuclear cells and neutrophils, was also noticed 1 day after treatment but not at other times and not in controls. Nonsuppurative, predominately histiocytic meningitis of decreasing intensity was noticed in dogs euthanatized at 1 or 5 days, but not in dogs euthanatized at 10, 20, or 30 days after treatment. The meningeal cells stained intensely with periodic acid-Schiff stain and intracellular contrast medium was ultrastructurally apparent in phagolysosomes. Control dogs killed after 30 days did not have these changes. The intrathecal administration of metrizamide resulted in transient leakage of serum components into CSF and an accompanying transient meningitis.     

Effects of insoluble and soluble dietary fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus

OBJECTIVE: To evaluate the effects of diets differing in type and quantity of fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus. DESIGN: Prospective randomized crossover controlled trial. ANIMALS: 7 dogs with well-regulated naturally occurring insulin-dependent diabetes mellitus. PROCEDURE: Dogs were fed 1 of 3 diets for 1 month each in 1 of 6 randomized diet sequences. Diets included a low-fiber diet (LF) and 2 high-fiber diets; 1 contained only insoluble fiber (HIF), and 1 contained soluble fiber in addition to insoluble fiber (HSF). Caloric intake was unchanged throughout the study. Glycemic control was assessed after each feeding trial by measuring serum fructosamine concentration and performing 5 serial measurements of blood glucose concentration every 2 hours after the morning feeding and insulin injection. RESULTS: Significant differences were not detected in body weight, required insulin dosage, or albumin concentration among dogs fed the HIF, HSF, and LF diets. Mean and maximum blood glucose concentrations and area under the blood glucose curve were significantly lower in dogs fed the HIF diet, compared with values in the same dogs fed the HSF or LF diet. Fructosamine concentration was significantly lower in dogs fed the HIF or HSF diet, compared with values in the same dogs fed the LF diet. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs with naturally occurring insulin-dependent diabetes mellitus, a dry, high insoluble-fiber diet may aid in glycemic control.     

Hypothalamic neurotransmitter concentrations and meat quality in stressed pigs offered excess dietary tryptophan and tyrosine.

Pale, soft, exudative (PSE) pork occurs, for the most part, from environmental stress on the pig. Amino acid intake may be related to stress susceptibility through hormone and neurotransmitter induction. Two experiments were conducted to determine whether supplementation of 5 g of tryptophan (TRP) or 10 g of tyrosine (TYR) per kilogram of a 14% CP diet would alter the response of pigs to stress as measured by hypothalamic neurotransmitter concentrations and incidence of PSE. Twenty-four (Exp. 1) and 36 (Exp. 2) 92-kg pigs were offered one of three diets: control, TRP-, or TYR-supplemented for 5 d before slaughter. Dietary TRP or TYR supplementation in Exp. 1. doubled (P less than .05) plasma TRP and TYR concentrations, respectively, and increased (P less than .05) 5-hydroxytryptamine, dihydroxyphenyl ethylamine, dihydroxyphenyl acetic acid, and homovanillic acid concentrations in the hypothalamus. Pigs that exhibited stress at slaughter had lower (P less than .05) hypothalamic concentrations of epinephrine, norepinephrine, and 5-hydroxytryptamine. In Exp. 2, pigs were trucked 55 km to a commercial meat packing facility and slaughtered without a rest period. This handling procedure was designed to invoke a high incidence of PSE pork and thus be a strong test of treatments. Supplemental dietary amino acids seemed to alter the frequency distribution of the severity of PSE pork. These data indicate that dietary manipulation of amino acid precursors of neurotransmitters may offer a practical means of reducing stress response in swine.     

Determination of immunoglobulin A concentrations in the serum and cerebrospinal fluid of dogs: an estimation of its diagnostic value in canine steroid-responsive meningitis-arteritis

Previous studies on canine steroid-responsive meningitis-arteritis (SRMA) suggested that elevation of immunoglobulin A (IgA) concentrations in both serum and cerebrospinal fluid (CSF) is specific for SRMA throughout the different disease stages. Recent studies however have raised concerns about the value of this test. The purpose of this study was to investigate the diagnostic value of IgA concentration testing in paired CSF and serum samples. IgA concentrations of 525 paired canine CSF and serum samples were evaluated. Samples were obtained from dogs with SRMA (n=311) and dogs with miscellaneous conditions (n=214) such as other central nervous system (CNS) inflammatory diseases (n=34), CNS tumours (n=46), idiopathic epilepsy (n=42), intervertebral disc disease (n=46) and non-CNS diseases (n=46). Serum IgA concentrations were significantly higher in dogs with untreated SRMA compared to those with other diseases. IgA CSF concentrations were significantly higher in dogs with SRMA compared to other disease categories, with the exception of inflammatory CNS disease. The sensitivity for IgA concentrations in serum and CSF was 91% with a specificity of 78%. Analysis of 525 paired samples confirmed that IgA concentrations were higher in dogs with SRMA. Calculation of the diagnostic value of IgA concentration confirmed that the test is highly sensitive for SRMA. Testing paired CSF and serum samples for IgA is still recommended for the diagnosis of suspected cases of SRMA.     

Cerebrospinal fluid analysis of rabid and vaccinia-rabies glycoprotein recombinant, orally vaccinated raccoons (Procyon lotor)

Cerebrospinal fluid obtained from clinically normal free-ranging raccoons was analyzed and compared with CSF obtained from raccoons vaccinated orally with vaccinia-rabies glycoprotein (V-RG) recombinant virus vaccine and subsequently challenged peripherally with street rabies virus, and CSF from naive, rabies virus challenge-exposed control raccoons. Significant differences were not found in CSF of free-ranging or V-RG recombinant virus vaccine recipient raccoons, and there was no evidence of CNS invasion by V-RG virus. The CSF of naive, rabies challenge-exposed control raccoons contained high numbers of lymphocytes and monocytes, compatible with rabies virus encephalitis. Although V-RG orally vaccinated challenge-exposed raccoons were protected from lethal rabies virus infection, a mild lymphocytic pleocytosis was evident at 90 days after challenge exposure.