Hypothalamus involvement in the reticulo-rumen motor and behavioural disturbances induced by morphine in sheep

Morphine (20 and 40 µg/kg) administered into the cerebral ventricle of conscious sheep caused significant inhibition of the mean frequency and the average amplitude of primary ruminal contractions by 45 min after injection. Between 90 and 120 min, morphine (40 µg) provoked a significant increase in the amplitude (p<0.01). At both doses it caused strong psychomotor excitability that lasted for more than 140 min. Isolation of the hypothalamus prevented both the inhibitory effects of morphine on rumen motility and the drug-induced psychomotor excitability. Histopathological analysis of slices of the hypothalamus, pons and medulla indicated descending degenerative changes in the nervous pathways connecting the hypothalamus with lower structures in the brain. These results suggest either that hypothalamic isolation caused degeneration of inhibitory descending pathways that connect the hypothalamus with the gastric centres or that structures of importance for forestomach motility are not located within the gastric centres but elsewhere in the brain, for example in the hypothalamus.Abbreviations Ach acetylcholine - CSF cerebrospinal fluid - ICV intracerebroventricular(ly) - NA noradrenalin - 6-OHDA 6-hydroxydopamine - PAGM periaqueductal grey matter     

Metabolic disturbances induced by organotins through subchronic treatment in chickens. Second communication: mineral metabolism

4 organotin derivatives (tributyltin acid, dibutyltin chloride, triphenyltin chloride, and triphenyltinbis (diethyl) dithiophosphate) were tested through subchronic treatment in 19 days old chickens. Their effects upon mineral metabolism were studied through biochemical investigations in kidney, bone, and blood. Bone mineral disturbances (depletion of Ca/P ratio) induced Ca elimination in blood, immobilised as calcium urates in kidney, and also increased values for alkaline phosphatase, following tin accumulation in bone. Butyl and phenyltin chloride were more toxic than dithiophosphate, and the intensity of effects was proportionate to the dose.     

Metabolic disturbances induced by organotins through subchronic treatment in chickens. First communication: growth dynamics, carbohydrate and protein metabolism

Four organotin derivatives (tributyltin acid, dibutyltin chloride, triphenyltinchloride, and triphenyltin-bis (diethyl) dithiophosphate) were tested through subchronic treatment on 19 days old chickens. Growth dynamics as well as carbohydrate and protein metabolism were investigated, in order to evaluate their effects on metabolic activity. Biochemical liver and blood constituents revealed growth retardation and general depression of metabolic activity in experimental groups. Some correlations were found to exist chemical structure, dose use for compound, and effects. Butyltins were more toxic than phenylderivatives and their effects were proportionale to the dose.     

Methemoglobinemia induced by a benzocaine-based topically administered anesthetic in eight sheep.

Benzocaine-based anesthetic sprays are commonly used in sheep to anesthetize the nasal passages and glottis before intubation. Sprays containing benzocaine have been identified as causing methemoglobinemia in dogs, cats, and human beings. Diagnosis of benzocaine-induced methemoglobinemia was made in 8 Dorset-Finn ewes exposed to a 2-second burst of (approx 56 to 112 mg of benzocaine) anesthetic spray. Venous blood samples taken 10 to 20 minutes after intranasal application of the spray revealed methemoglobinemia of 22.6 +/- 1.8% (mean +/- SD) in 9 samples from 8 ewes. Four other ewes intentionally exposed did not have methemoglobinemia. Topical use of benzocaine-containing anesthetics in sheep is not recommended. The high methemoglobin concentration induced by this product may substantially alter the cardiovascular and pulmonary function, blood gas analyses, and exercise capacity, thereby compromising animal health and/or research results. Although it appears that minimal clinical signs are induced in healthy animals, the risks of compromising a subclinically ill animal do not offset the benefits of this product.     

Airway hypersensitivity induced by Ascaris suum extract in New Zealand Romney sheep

Sheep from local farms with and without previous exposure to pigs were tested for their skin and airway responses to a commercial Ascaris suum antigen. There was an immediate reaction to intradermal injection of the antigen in 90% of 101 sheep. A bronchial provocation test by aerosol of the same antigen was undertaken on 43 of the sheep with a positive skin reaction. About 70% of sheep showed an immediate airway response to the antigen as an aerosol, reflected as a significant increase in airway resistance and/or decrease of dynamic lung compliance. The mean peak airway resistance and mean lowest dynamic lung compliance were 165% above and 61% below their baselines, respectively. No significant changes were recorded when the same animals were given an aerosol of phosphate buffered saline. Similarly, no correlation was found between the degree of skin reaction and the magnitude of bronchoconstriction (p>30.05). The sheep with previous exposure to pigs showed no significant differences in airway responses to antigen challenge, although they showed significantly greater skin reactions than those without exposure to pigs. These results indicate that the majority of Romney sheep in the Manawatu have a natural skin and airway sensitivity to A. suum antigen and may therefore be used as an animal model to study human airway hypersensitivity. The origin of this sensitivity has yet to be determined.     

Influence of food intake on the absorption of lysine-acetylsalicylate in dogs

The influence of food intake on the absorption of a water-soluble aspirin, lysine-acetylsalicylate, was examined in six healthy adult mongrel dogs. Single-dose kinetics were determined following ingestion of 90 mg/kg of lysine-acetylsalicylate in dogs either fasted for 12 h or following a standard meal of either dry food or the same meal containing 20% of olive oil. Concurrent intake of food both reduced the serum salicylate concentration for 3 h after administration, and reduced the total amount of drug absorbed as reflected by the area under the plasma concentration/time curve(AUC). The effects were more pronounced following the fatty meal. Data from this investigation suggest that lysine-acetylsalicylate is therapeutically effective, without side effects when taken at the rate of 80 mg/kg at 12 h intervals, during or after feeding rather than before feeding.     

Airway hypersensitivity induced by Ascaris suum extract in New Zealand Romney sheep

Sheep from local farms with and without previous exposure to pigs were tested for their skin and airway responses to a commercial Ascaris suum antigen. There was an immediate reaction to intradermal injection of the antigen in 90% of 101 sheep. A bronchial provocation test by aerosol of the same antigen was undertaken on 43 of the sheep with a positive skin reaction. About 70% of sheep showed an immediate airway response to the antigen as an aerosol, reflected as a significant increase in airway resistance and/or decrease of dynamic lung compliance. The mean peak airway resistance and mean lowest dynamic lung compliance were 165% above and 61% below their baselines, respectively. No significant changes were recorded when the same animals were given an aerosol of phosphate buffered saline. Similarly, no correlation was found between the degree of skin reaction and the magnitude of bronchoconstriction (p>0.05). The sheep with previous exposure to pigs showed no significant differences in airway responses to antigen challenge, although they showed significantly greater skin reactions than those without exposure to pigs. These results indicate that the majority of Romney sheep in the Manawatu have a natural skin and airway sensitivity to A. suum antigen and may therefore be used as an animal model to study human airway hypersensitivity. The origin of this sensitivity has yet to be determined.     

Staggers induced by consumption of perennial ryegrass in cattle and sheep from northern California

Staggers was diagnosed in sheep and cattle from the northern California coast. The diagnosis was made on the basis of history of ingestion of perennial ryegrass (Lolium perenne) stubble, clinical signs of transient ataxia, which was aggravated by stimulation, and nearly complete recovery after removal of ryegrass as the primary forage. Morbidity was high, but death did not occur in any affected animals. The toxic endophyte, Acremonium lolii, was in most lower leaf sheaths from the ryegrass. Injection of extracts of the ryegrass from affected farms into mice induced signs of toxicosis. Additionally, ryegrass from all 3 farms contained the tremorgenic mycotoxin, lolitrem-B.