Plasma and urine electrolyte and mineral concentrations in Thoroughbred horses with recurrent exertional rhabdomyolysis after consumption of diets varying in cation-anion balance

OBJECTIVE: To determine whether plasma, urine, and fecal electrolyte and mineral concentrations differ between clinically normal horses and Thoroughbreds with recurrent exertional rhabdomyolysis (RER) after consumption of diets varying in cation-anion balance. ANIMALS: 5 Thoroughbred mares with RER and 6 clinically normal mixed-breed mares. PROCEDURE: Each of 3 isocaloric diets designated as low, medium, and high on the basis of dietary cation-anion balance (DCAB) values of 85, 190, and 380, respectively, were fed to horses for 14 days. During the last 72 hours, 3 horses with RER and 3 control horses had daily urine and fecal samples obtained by total 24-hour collection. Remaining horses had urine samples collected daily by single catheterization. RESULTS: For each diet, no differences existed between horses with RER and control horses in plasma pH, electrolyte concentrations, and creatine kinase activity or in urine pH and renal fractional excretion (FE) values. Plasma pH, strong ion difference, bicarbonate and total carbon dioxide concentrations, and base excess decreased and plasma chloride and ionized calcium concentrations increased with decreasing DCAB. Urine pH decreased with decreasing DCAB. The FE of chloride and phosphorus were greatest for horses fed the low diet. The FE values for all electrolytes exept magnesium did not differ between urine samples obtained by single catheterization and total 24-hour collection. Daily balance of calcium, phosphorus, sodium, chloride, and potassium did not differ significantly among horses fed the various diets. CONCLUSIONS: In clinically normal horses and in horses with RER, the DCAB strongly affects plasma and urine pH and the FE of sodium, potassium, chloride, and phosphorus.     

Surveillance for highly pathogenic avian influenza in migratory shorebirds at the terminus of the East Asian-Australasian Flyway

AIM: To determine if migratory birds arriving in New Zealand in the Southern Hemisphere spring of 2004 were infected with the highly pathogenic avian influenza (AI) virus, H5N1.

METHODS: Cloacal and faecal samples were collected from migratory red knots following their arrival in New Zealand in October 2004. Two species of resident sympatric birds, wrybill and mallard duck, were sampled prior to, and following, the arrival of migratory birds.

RESULTS: No AI viruses were isolated from migratory or resident shorebirds. Non-pathogenic AI viruses were isolated from six resident mallard ducks, comprising the endemic subtypes H4 (n=2), H7 (non-pathogenic), H10, and H11 (n=2).

CONCLUSIONS: Highly pathogenic AI H5N1 virus was not detected in migratory shorebirds or sympatric water birds in the Firth of Thames, New Zealand, in 2004-2005, despite the possible proximity of migratory birds to outbreaks of the disease in East Asia in 2004.     

Equine Protozoal Myeloencephalitis: A Report of Two Cases From Western Canada

Two cases of nonsuppurative myeloencephalitis are reported which clinically and pathologically resemble equine protozoal myeloencephalitis. Lesions in both horses were associated with Toxoplasma-like organisms visible in microscopic sections. Clinical signs and lesions in one case primarily involved the brain and in the other case principally involved the spinal cord and associated meninges. Positive identification of the organisms was not achieved; however, the etiological agent is unlikely to be a species of Toxoplasma. Recently published studies suggest a species of Sarcocystis is involved.     

Diarrhoea associated with cryptosporidial oocyst shedding in a quarterhorse stallion

Cryptosporidial oocyst shedding was detected in a 2.5-year-old Quarterhorse stallion with diarrhoea. Based on the detection of cryptosporidial oocysts, and the absence of other aetiological agents or enteropathogens, cryptosporidiosis was presumptively diagnosed. This case was unusual because cryptosporidial oocyst shedding is primarily found in some immunocompromised or immature horses, and has not been reported in healthy mature horses.     

ANGIOSTRONGYLUS CANTONENSIS INFECTION OF THE BRAIN OF A CAPTIVE BENNETT'S WALLABY (MACROPUS RUFOGRISEUS)

SUMMARY Eleven immature adult Angiostrongylus cantonensis were recovered from beneath the meninges of a captive Bennett's wallaby (Macropus rufogriseus) which died after displaying posterior paresis followed by paralysis and intermittent opisthotonic spasms of increasing frequency for 7 days. Congestion and focal malacia with haemorrhage were seen in the brainstem and cerebellum. Sections of worms with scanty inflammatory response were seen beneath the congested haemorrhagic leptomeninges of cerebrum and in a cerebellar folium.
Infection was thought to have originated from feed or water contaminated with larvae released from a molluscan intermediate host.     

The frictional behaviour of wood

Summary The work described was primarily concerned with determining the more important variables affecting friction between wood and steel, but friction between wood and non-ferrous materials including wood itself was also investigated briefly. Deviations from the classical laws of friction were of interest, the most significant being variation of friction coefficient with sliding speed. With an increase in sliding speed up to 4 m/sec the curves for highly polished steel showed undulations, but with unpolished surfaces there was a monotonic reduction, somewhat greater in wet wood than dry. Other important factors, interacting with sliding speed, were steel roughness and wood moisture content. Effects of load, nominal contact area and fibre direction were minor. The results appear to be adequately explained in terms of adhesion and lubrication.A world wide selection of species was tested, and it appears that the nature and amount of extractives in most woods is such that they have similar friction coefficients except on very smooth steel, and only a few greasy species, have significantly lower coefficients. For most air-dry wood in contact with unpolished steel, the coefficient decreases from a static value about 0.65 to a value about 0.4 at 4 m/sec. For wet wood, the corresponding values are about 0.7 and 0.15.Coefficients of friction between wood and wood were similar to those between wood and rough steel, and those between wood and other materials varied in a manner which may be related to strength of adhesion.

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Zusammenfassung Die ursprüngliche Zielsetzung der Arbeit, die Untersuchung der wesentlichen Einflußgrößen auf die Reibung zwischen Holz und Stahl wurde durch Einbeziehung von Nichteisen-Metallen und der Reibung zwischen Holz und Holz erwitert. Als bemerkenswert stellten sich die Abweichungen von den klassischen Reibungsgesetzen heraus, am auffallendsten die Änderung der Reibung mit der Vorschubgeschwindigkeit. Beim Anstieg der Vorschubgeschwindigkeit bis zu 4 m/s zeigten die Kurven für hochglanzpolierten Stahl Unstetigkeiten, während bei unpoliertem Stahl ein gleichförmiger Abfall eintrat, der bei nassem Holz etwas größer war als bei trockenem. Weitere wichtige Einflußgrößen waren Stahlart und Holzfeuchtigkeit. Die Wirkungen von Normaldruck, Kontaktfläche und Faserrichtung waren von untergeordneter Bedeutung. Die erzielten Ergebnisse lassen sich in etwa gleicher Weise durch Begriffe aus den Gebieten der Adhäsion oder der Schmierung beschreiben.Es wurde angestrebt, möglichst alle wichtigen Holzarten der Welt zu erfassen. Man kann sagen, daß die Inhaltsstoffe der meisten Hölzer nach Art und Menge zu ziemlich ähnlichen Reibungskoeffizienten führen, ausgenommen bei sehr glatten Stahlarten. Nur wenige fetthaltige Holzarten weisen deutlich niedrigere Reibungskoeffizienten auf. Für lufttrockenes Holz und unpolierten Stahl fällt der Koeffizient von 0,65 für Haftreibung auf 0,40 für gleitende Reibung bei 4 m/s Vorschubgeschwindigkeit. Bei nassem Holz lauten die entsprechenden Werte 0,70 und 0,15. Die Reibungskoeffizienten zwischen Holz und Holz waren ähnlich denen zwischen Holz und rauhem Stahl; diejenigen zwischen Holz und anderen Materialien variierten so, daß ein Zusammenhang mit den Adhäsionskräften anzunehmen ist.

     

Pharmacokinetics and safety of firocoxib after oral administration of repeated consecutive doses to neonatal foals

The purpose of this study was to determine the pharmacokinetics and safety profile of firocoxib in neonatal foals. Seven healthy foals were administered 0.1 mg/kg firocoxib orally q24 h for nine consecutive days, commencing at 36 h of age. Blood was collected for firocoxib analysis using high‐pressure liquid chromatography with fluorescence detection at 0 (dose #1 only), 0.25, 0.5, 1, 2, 4, 8, 16, and 24 h after doses 1, 5, and 9. For all other doses (2, 3, 4, 6, 7, and 8), blood was collected immediately prior to the next dose (24 h trough). Elimination samples (36, 48, 72, 96, 120, and 144 h) were collected after dose 9. Safety was assessed via physical examinations, body weight measurements, gastroscopy, complete blood count, plasma biochemistry and urinalysis. Firocoxib was rapidly absorbed following oral administration with minimal accumulation after repeat dosing. After the final dose, the terminal half‐life was approximately 11 h. Firocoxib was below the limit of detection (<2.5 ng/mL) in plasma 72 h after the final dose. No significant abnormalities were found on blood analyses, urinalysis, or gastroscopy. This study demonstrated that firocoxib is absorbed in neonatal foals with no demonstrable adverse effects after repeated doses of 0.1 mg/kg.     

Oxygen consumption and ventilatory reflex responses are influenced by dietary lipids in sturgeon

The effects of one year's feeding with diets enriched either in highly unsaturated fatty acids of the w3 series (w3 HUFA) (fish oil-supplemented diet, FOD) or in saturated fatty acids (SFA) (coconut oil-supplemented diet, COD) on fatty acid composition of tissue lipids, on patterns of resting oxygen consumption and on responses to hypoxia and hypercapnia were investigated in the Adriatic sturgeon (Acipenser naccarii). FOD sturgeon had higher levels of w3 HUFA in liver and muscle lipids than COD fish, which had higher levels of SFA. A frequency distribution of instantaneous oxygen uptake rates (M]O2), as measured every 10 min for 8 h, revealed a different pattern of resting oxygen consumption between the two groups. The FOD sturgeon consumed oxygen in a narrow range of low rates, with a lower mean M]O2 than COD sturgeon, which showed a wide range of more elevated rates. FOD sturgeon had a lower opercular pressure amplitude than COD fish in normoxia. Exposure to three levels of hypoxia PO2s = 10.8±0.2; 6.6±0.2 and 4.6±0.2 kPa) or mild hypercapnia (PCO2 = 1.0±0.2 kPa) did not affect ventilation in FOD fish but elicited hyperventilation in COD animals. Mild hypoxia (PO2 = 10.8±0.2 kPa) and hypercapnia caused less reduction in blood oxygen content in FOD as compared with COD sturgeon. The effects of adding vitamin E supplements to the diets was investigated; groups fed vitamin E supplements had elevated M]O2 and hyperventilated in hypoxia. The data indicate that dietary fatty acid composition influences resting M]O2 in sturgeon and that this influences the regulation of ventilation and blood O2 levels in hypoxia and hypercapnia. The low resting M]O2 of fish fed w3 HUFA supplements (the FOD group) obviated the need for hyperventilation in hypoxia or hypercapnia, thereby making them less sensitive to these stresses than sturgeon fed SFA (COD group) or sturgeon fed either diet supplemented with vitamin E. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of changes in plasma pH,CO2 and ammonia on ventilation in trout

We investigated ventillatory responses to a plasma alkaloids and hypocapnia,a nd the basis for the ventilatory response to sodium bicarbonate (NaHCO₃) infusion in rainbow trout. Plasma alkalosis and hypocapnia created by infusion of sodium hydroxide (NaOH) did not cause hypoventilation, whereas infusion of hydrochloric acid (HCl) caused vigorous hyperventilation, associated with an acidosis, a reduction in blood O₂ content (Ca_{O 2}) and a release of circulating catecholamines. Infusion of NaHCO₃ stimulated ventilation and caused an increase in plasma pH, total carbon dioxide content (Ca_{CO 2}) and catecholamine levels, and a reduction in oxygen tension (Pa_{O 2}). Infusion of ammonium bicarbonate (NH ₄HCO₃) caused hyperventilation and was associated with an increase in Ca_{CO 2} and plasma total ammonia (C_amm) and ammonia gas (NH₃) concentration. Infusion of sodium chloride (NaClI) and Cortland's saline had no effect on ventilation. The results indicate that trout do not exhibit the ventilatory sensitivity to pH seen in terrestrial vertebrates. Ventilatory responses to NaHCO₃ appear to have been a result of reductions in Pa_{O 2}, a release of catecholamines and an increase in Ca_{CO 2} whereas responses to NH₄HCO₃ appear to have been a result of increases in Ca_{CO 2} and C_amm.