ACQUIRED MEGAESOPHAGUS IN A HEIFER

An 18-month-old pregnant heifer, hitherto normal, was noticed to regurgitate wet, partially digested roughage several times a day. On clinical examination, the heifer was losing body weight. There was no obstacle to passing a stomach tube to the rumen. A barium study of the esophagus was performed. Megaesophagus involving the cervical and cranial thoracic esophagus was diagnosed. Postmortem findings were a dilated esophagus, with no gross pathology seen. Histopathology showed extensive submucosal cellular infiltration of eosinophils. The classification and possible etilogy of the case is discussed.     

THE EFFECT OF XYLAZINE HYDROCHLORIDE ON THE RADIOGRAPHIC APPEARANCE OF THE STOMACH AND INTESTINE IN THE DOG

Twelve dogs of various breeds, age and weight were injected with xylazine hydrochloride by intravenous and intramuscular routes at various doses. Radiographs of the abdomen were made prior to and at 30, 60 and 90 minutes after injection. The drug produced dilatation of the stomach and the intestines. Radiographic changes were consistent with gastric dilatation and paralytic ileus     

Measuring the costs of improving the quality of the environment in the United States

The analysis in this paper is directed at comparing the relative effectiveness of meeting the objectives outlined in the recently passed Clean Air Act Amendments of 1990 through taxation and through regulation. The analytical vehicle used in the analysis consists of a computable general equilibrium model composed of 12 producing sectors, 13 consuming sectors, 6 household categories classified by income, a foreign sector and a government. We find first that, irrespective of what type of strategy is followed, both output and consumption decline. Hence, there is an identifiable and quantifiable tradeoff between economic activity (economic growth) and the quality of the environment. Beyond this, the aggregate loss in production and economic welfare (measured by consumption expenditures and utility) is less under a policy which stresses reliance on alternative fuels than through one that requires the installation of pollution abatement devices.     

Avocado rootstock influences scion leaf mineral content

ABSTRACT

To test the influence of avocado rootstocks on the scion leaf ionome, the nutritional status of avocado cultivars Hass and Ettinger grafted onto 15 rootstocks was compared over 3 years. The rootstocks were of different genetic origins (West Indian or Mexican) and were clonally or reproductively propagated. The trees were grown in a high-density orchard, and were continually fertigated as is common in modern avocado orchards. Leaf mineral composition was analysed and found to be correlated with crop load. ‘Hass’ leaves had significantly higher levels of B, Ca, Mg, Na, P and K than ‘Ettinger’ leaves. Rootstocks of Mexican origin produced higher foliar Cl levels, but lower levels of Mg and Mn. Rootstocks grown from seedlings conferred higher foliar K and lower B, Ca and Mg. The results demonstrate that avocado rootstocks affect the nutritional status of the tree, by a differential mineral transport, which is indicated by the scion leaf ionome.     

Tree age effect on fine-root and leaf morphology in a silver birch forest chronosequence

The influence of forest ageing on fine-root morphology and relations between fine-root and leaf characteristics is poorly studied. The aim of this study was to analyse age-driven changes in ectomycorrhizal roots (EcM roots) and leaf morphology in a chronosequence of silver birch (Betula pendula Roth.), which would provide a better understanding of adaptation responses and acclimation capacity of tree roots and leaves. The chronosequence included six age classes (3, 6, 14, 32, 45, and 60 years.). All stands had regenerated naturally and grew in a highly productive Oxalis forest site type in Estonia. Most changes in the morphology of EcM roots and leaves of silver birch occur faster at a young age. The functional parameters—mean specific area of EcM root (SRA) and leaf specific area (SLA) as well as leaf N—decreased with age. EcM root SRA and specific root length (SRL) decreased with stand age as a result of increased mean diameter and tissue density. In age classes of 6, 14, and 32 years, the total number of dominating EcM taxa was 34, and the distribution of four different dominating EcM exploration types (contact-, short-, medium-, long-distance) was similar. We conclude that high values of SRA, SLA, and leaf N measured in young silver birch stands indicate high activity of physiological processes necessary for fast-growing young trees. A decrease of SLA and SRA and N in the chronosequence of fertile stands of silver birch is most probably caused by down-regulation of growth, affecting simultaneously leaves and fine roots.     

Effect of plant development on turbulent fluxes of a screenhouse banana plantation

This study focuses on CO₂ and water vapor flux measurements, water use efficiency estimates and evapotranspiration modeling during the course of growth of a young banana crop in a screenhouse in northern Israel. An eddy covariance system was deployed at the center of the screenhouse during two growth periods of the banana crop: small and large plants. Results show that daily whole canopy evapotranspiration increased during the measurement period from 2.2 mm day^?1 for the smaller plants to 3.4 mm day^?1 for the larger plants. The increase in net daily CO₂ consumption doubled during the same period, from about 11 to 21.5 g m^?2 day^?1 per unit ground area. Water vapor and CO₂ fluxes per unit leaf area were independent of plant size and averaged with 51 and 0.29 g m^?2 day^?1, respectively. Consequently, water use efficiency, defined as the ratio between net vertical fluxes of CO₂ and water vapor, was nearly constant during growth of the plants. Evapotranspiration models provided more accurate predictions for larger than for smaller plants. This was due to inadequate treatment of the partial cover of young plants, which could be overcome by the use of a crop coefficient. A modified Penman–Monteith evapotranspiration model adapted to the screenhouse environment, applied here for the first time to a banana screenhouse, was in better agreement with the measurements than an open canopy model.     

Postanesthetic cerebellar dysfunction in cats

Eleven cats with signs of cerebellar dysfunction, developed on recovery from a brief and uneventful general anesthesia, were examined at the Koret School of Veterinary Medicine Teaching Hospital (KSVMTH) between 1998 and 2002. Neurological signs included mild to severe ataxia of all 4 limbs, intentional tremor, lack of menace response, and delayed hopping. The cats were of different ages when anesthetized and none had shown any prior signs of neural disease. They were examined 1 day to 4 years after onset of clinical signs, and the neurological deficits remained unchanged in a follow-up period of 6 months to 8 years. Medical and anesthetic records showed that all were Persian cross cats, 7 of them originating in the same city in Israel. Ketamine was the only anesthetic drug that had been used with all cats. It might be that a genetic component predisposes Persian cross cats to nonreversible cerebellar damage after exposure to an anesthetic dose of ketamine.     

Sub-occipital craniectomy in a lion (Panthera leo) with occipital bone malformation and hypovitaminosis A

Neurologic dysfunction accompanied by malformation of both the skull and the cervical vertebrae has been previously described in lions kept in captivity worldwide, and this dysfunction and malformation were most often related to vitamin A deficiency. Diagnosis of the bone malformation and its effects on the neural tissue was until recently limited to postmortem examination, with characteristic thickening of the bones of the cranial vault, cerebellar herniation, compression of the foramen magnum, and enlargement of the lateral ventricles. For some mildly affected lion cubs with neurologic signs, improvement was reported with excessive vitamin A supplementation. However, definitive diagnosis was only available for those that eventually died or were euthanized. This case documents the antemortem diagnosis of the disease using computed tomographic imaging and liver biopsy. While conservative treatment failed, suboccipital craniectomy removed the thickened occipital bone and was demonstrated to be a successful surgical intervention that can be used to treat more severely affected lions.     

Bite wounds involving the spine: characteristics, therapy and outcome in seven cases

Medical records of five dogs and two cats with bite wounds to the spine were reviewed. All dogs were bitten in the cervical spine and presented as quadriparetic. Both cats were bitten at the lumbar spine; one was paraparetic and the other paraplegic. Concomitant injuries to structures other than the spine were seen in two cases. Radiographic findings included vertebral fractures in all cases. Medical therapy included antibiotics (7/7), methylprednisolone sodium succinate (4/7) and analgesia (7/7). Five cases underwent minor (4/5) or extensive (1/5) surgical debridement. All cervical fractures were stabilized with fiberglass casts and animals with lumbar injury were cage rested for a month. Six of the cases survived, five of which regained good to excellent ambulatory ability within the first month. Although, the numbers of reported cases are limited, this study shows that adequate surgical debridement and wound drainage combined with external coaptation can be sufficient to manage bite wounds that involve the spine.