Stomach ulcers in the horse--clinical and gastroscopic findings in 12 horses (1989-1990)

Twelve horses with clinical symptoms of a gastric disorder were studied by gastroscopy. Symptoms of gastric disorders were periprandial colic, bruxism, ructus and reflux. Preliminary to gastroscopy the horses were fasted for 24 h. Access to water was not restricted. The gastroscopy could be conducted easily using a fiberscope 2.5 m in length and 11 mm in outer diameter. While ulcers were present in the squamous fundus of all horses only one horse showed ulceration of the glandular fundus. Solitary ulcers near the margo plicatus were found in horses with mild clinical symptoms. In contrast, diffuse gastroesophageal ulceration was accompanied by severe clinical symptoms. Four horses were affected by an acute gastroesophageal ulceration with gastric reflux and subsequent aspiration pneumonia. Two of those horses suffered from acute gastric ulceration 3-4 days following laparatomy. All horses were treated with cimetidine (5 mg/kg bwt/q.i.d.) until clinical symptoms ceased.     

Antithrombin III determination in horses. Reference values and acquired antithrombin III deficiency

Antithrombin III (AT III) determinations were done in healthy and sick horses using the chromogenic substrate Chromozym TH. Reference values for adult horses at 25 degrees C were 18-25 IU AT III per ml plasma and 84-118% AT III activity of normal horse plasma, respectively. Precision and accuracy were good (intra assay coefficient of variation less than 2%, accuracy 10%). Surgical operations on healthy horses led to a biphasic decrease in AT III activity touching the lower border of the reference values on the second postoperative day. Other reasons for acquired AT III deficiencies included disseminated intravascular coagulation (DIC), liver disease and glomerulonephritis. Using follow-up studies, differences in the dynamics of acquired AT III deficiency and coagulation promoting factors were demonstrated. 12 of 35 horses with decreased AT III values suffered from phlebothrombosis of the jugular veins. It was presumed that acquired AT III deficiencies promote development and progression of phlebothrombosis/thrombophlebitis in horses.     

Selected pathological, immunohistochemical and ultrastructural changes associated with an infection by Diphyllobothrium dendriticum (Nitzsch, 1824) (Cestoda) plerocercoids in Coregonus lavaretus (L.) (Coregonidae)

The pathological changes induced by an infection of Diphyllobothrium dendriticum (Nitzsch, 1824) plerocercoids in powan, Coregonus lavaretus (L.), from Loch Lomond, Scotland, were assessed using immunohistochemical and ultrastructural techniques. In a sample of 26 powan, the occurrence of encysted plerocercoids of D. dendriticum on the outer surface of the stomach was 38.5% (n = 10) with the number of cysts ranging from 4 to 15 and measuring 4.2 +/- 1.0 mm x 3.4 +/- 0.9 mm (mean +/- SD). Histological examination of intestinal samples also revealed plerocercoids (2-21) encapsulated within a proliferation of mesenteric fibrous tissues of the gastric wall and, occasionally, by the gut lamina propria-submucosa and lamina muscularis. In section, cysts were tri-layered and were formed from a series of concentric whorls of fibroblast and collagen fibre-based connective elements. The extent of necrosis within each muscle layer and the serosa of the stomach differed, notably within the latter that was marked by a chronic inflammatory reaction and fibrosis. Within the cyst and around it, a large number of degranulating mast cell/eosinophilic granule cells were seen, in addition to melano-macrophage centres. Immunohistochemical staining of sections of infected stomach revealed a high density of elements, in close proximity to plerocercoids, staining positive for serotonin, bombesin, substance P and galanin. Uninfected material did not present the same levels of activity. Sections through both infected and uninfected tissue were also tested for elements containing vasoactive intestinal peptide, met-enkephalin, calcitonin gene-related peptide, neuropeptide Y and nitric oxide synthase, but these were absent.     

The treatment basis for anticoagulants in horses

The pharmacokinetics of racemic phenprocoumon were studied in 8 adult horses after the single intravenous and oral administration of 0.75 mg/kg. After i.v. administration the plasma concentration of phenprocoumon showed a biphasic decline in time. The pharmacokinetics were calculated on the two-compartment open model. The average plasma half-life (beta-phase) was 22 hours, the apparent volume of distribution was 0.61 l/kg, Cltot was 25.2 ml/kg/h (13.9-40.9 ml/kg/h). The systemic bioavailability of oral phenprocoumon was 97.6%, Tmax was found to be 4-12 hours. The effect of phenprocoumon on the coagulation system was determined by the activity of Factor X, the Quick's one stage prothrombin time and the PTT. Factor X showed the most marked effect. A reduction of the content of Factor X was seen over 7-9 days, it decreased to 11-33%. Quick's one stage prothrombin time was reduced over 4-8 days, the lowest values were 22-55%. The PTT showed only a small reaction on the single administration of 0.75 mg/kg phenprocoumon. Differences in the effect on the coagulation between the i.v. and the oral administration could not be observed. In comparison to warfarin, phenprocoumon showed a longer t0.5 (beta) and produced a markedly longer hypothrombogenic reaction. Therefore phenprocoumon appeared to be more suitable for a long term anticoagulation therapy in horses than the structurally related warfarin.     

Effect of feeding and fasting on plasma tryptophan and tryptophan to large neutral amino acid ratio,and on brain serotonin turnover in rainbow trout,Oncorhynchus mykiss

Two time-course experiments were conducted to determine the effect of feeding and fasting on the plasma ratio of tryptophan (trp) to the large neutral amino acids (LNAA), (trp/LNAA ratio) and brain serotonin (5-HT) turnover in rainbow trout,Oncorhynchus mykiss. Trout were fasted overnight or for 3 days and were then either fed or continued to be fasted for up to a further 3 days. Changes in plasma trp, plasma trp/LNAA ratio, brain trp, brain 5-HT, brain 5-hydroxyindoleacetic acid (5-HIAA) and brain 5-HIAA/5-HT ratio were determined over time. Feeding decreased the plasma trp/LNAA ratio, brain trp and the brain 5-HIAA/5-HT ratio. In addition, in fish sampled over 3 days, there appeared to be a rhythm in plasma trp and the brain 5-HIAA/5-HT ratio which was independent of feeding. These results indicate that in rainbow trout, feeding is a sufficient physiological event to decrease brain 5-HT turnover. Furthermore, feeding-independent changes in the brain 5-HIAA/5-HT ratio, which were evident in fasted fish sampled over 3 days, also suggest an additional, non-feeding-related modulator(s) of brain 5-HT turnover in rainbow trout.     

Diagnostic possibilities of ANP blood measurements in dogs]

Atrial natriuretic peptide has been considered to be a major regulator in the body's water and salt homeostasis. Antagonizing those mechanisms leading to volume retention and overload (renin, angiotensin, aldosterone), ANP has been suggested to play a critical role in the pathology of certain diseases like renal failure, congestive heart failure or hypertension. In this regard, we measured ANP plasma concentration in normal healthy dogs and dogs with renal failure, congestive heart failure and Cushing syndrome. ANP levels were slightly decreased in dogs with Cushing disease (n = 9; 5.5 +/- 2 fmol/ml), increased in renal failure (n = 7; 16.2 +/- 5.8 fmol/ml, p less than 0.05) and markedly augmented in dogs with congestive heart failure (n = 14; 52.9 +/- 29.75 fmol/ml, p less than 0.01) as compared to healthy dogs (n = 6; 8.3 +/- 3.5 fmol/ml). Furthermore, characterization of the measured immunoreactivity (IR-ANP) revealed, that up to 50% of the IR-ANP in dogs with congestive heart failure corresponds to the ANP precursor molecule, not found in healthy subjects. This fact might present one possible explanation for the attenuated response to ANP in congestive heart failure. In addition, this finding may also serve a diagnostical purpose.     

Determination of the selenium levels of the blood plasma in newborn calves--its significance from the clinical viewpoint

In a collection of newborn calves including DRB, DSB and DFV breeds (n = 27) the plasma Selenium concentration was measured directly after parturition up until six weeks after parturition by means of neutron-activating analysis. Minimal Selenium concentration occurred on the fourth day. The values of the subsequent Selenium concentrations exceeded those immediately after parturition only slightly. The tested group could be divided into two subgroups, one of which consisted of calves with extremely low initial Selenium concentrations, whereas the animals in the others showed high levels immediately after parturition (0.019 +/- 0.004 micrograms/ml versus 0.046 +/- 0.010 micrograms/ml of plasma). The diagrams appeared to be parallel on two different levels. Nine out of 10 calves with low Selenium levels showed after parturition retarded development and/or suffered from various diseases whereas the other calves (n = 17) showed no signs of clinical disease nor alterations in the race-specific development throughout the testing period.     

Distended, water-filled stomach in sea-farmed rainbow trout

A syndrome of abdominal distension has been described in sea-farmed rainbow trout (Oncorhynchus mykiss). The anomaly was investigated with respect to changes in morphology, osmoregulation and nutritional status in 0.7-2-kg fish. The fish were visually classified according to the degree of abdominal distension as normal, moderately affected or markedly affected. The thickness of the abdominal wall was greatly reduced in the affected compared to the normal fish. The mean stomach contents of the moderately and markedly affected fish were two and six times higher than the normal, respectively. There was an increased amount of water in the stomach contents of both groups of affected fish, while no differences in stomach dry matter content were documented between the three groups. In about half of the normal group and in most of both the affected groups there was a marked accumulation of fat in the stomach, visible as a distinct dark-coloured oil layer. There were no intergroup differences in the water, fat or dry matter contents in the small and large intestine digesta. Both groups of affected fish had less visceral and muscle tissue fat than normal fish. The occurrence of an opaque, whitish blood plasma was greater among the affected than the normal fish. The affected fish had a higher mean blood plasma osmolality and Na⁺ and Cl⁻ concentration than the normal fish. An increased plasma concentration of glucose and insulin, but a decreased cholesterol concentration, were also measured in the affected fish. There were no intergroup differences in the condition factor of the fish.     

Experimental production of gastric dilation and its association with osmoregulatory stress and biogenic amines in chinook salmon, Oncorhynchus tshawytscha (Walbaum)

Chinook salmon smolt in fresh water fed a commercial diet known to produce minimal gastric dilation and air sacculitis (GDAS) were randomly assigned to four experimental tanks with flow-through sea water. All four groups were acclimatized to sea water for 3 weeks and fed a diet of minced fresh seafood. After 3 weeks the groups were fed either; seafood as before, a different commercial pelleted diet associated with the development of GDAS on farms, or either diet supplemented with 500 mg L(-1) putrescine, 300 mg L(-1) cadaverine and 250 mg L(-1) tyramine. Gastric dilation was produced in fish fed the commercial diet for 1 month but not by feeding a diet of minced seafood. The addition of putrescine, cadaverine and tyramine to either diet had no significant effect on the development of gastric dilation. Fish fed the commercial diet had significantly (P < 0.0001) wider weight-adjusted stomach widths, less prominent longitudinal stomach folds (P < 0.0001) and lower (P < 0.0001) stomach-width ratios than fish fed the fresh seafood diet. There was no significant difference in serum osmolality or sodium concentration between fish from groups with or without gastric dilation or fed biogenic amines.     

Acidification of the stomach contents of weaned piglets--effect of feed quantity and composition

The pH in the stomach chyme (5-8 hours past offering the diet) of reared piglets was strongly correlated to the ingested feed quantity, a complete acidification of the stomach contents occurred in restrictively fed piglets (15 g diet/kg BW) only. Feeding ad libitum resulted in comparable low pH values in the fundus and pylorus region only, whereas in the cardiac region high pH values (5-6.5) were observed. Formic acid as feed additive (5 ml/kg diet) did not influence the pH in stomach contents significantly, on the other hand the ingestion of a diet with high CaCO3 content (59 g Ca/kg DM) prevented the acidification of the stomach chyme totally. The variation of pH-values in the different areas within the stomach was caused mainly by the variation of hydrochloric acid concentrations, the influence of lactic acid concentration was negligible.     

Total and free thyroid hormones in plasma of tropical marine teleost fish

Plasma levels of L-thyroxine (T₄) and 3,5,3-triiodo-L-thyronine (T₃) and the percentage of plasma T₄ and T₃ present in the free (dialyzable) form (%FT₄ and %FT₃) were measured in 16 species (11 families) of tropical marine teleosts from an inshore Barbados reef. Mean plasma T₄ varied from 0.2 ng/ml to 42 ng/ml; mean plasma T₃ varied from < 0.2 ng/ml to 50 ng/ml. The highest T₄ and T₃ levels were recorded in parrot-fish and the lowest levels in filefish. The %oFT₄ and %FT₃ varied from 0.05–3.41%. Estimated levels of plasma free T₄ and free T₃ levels ranged from 0.4–466 pg/ml. The extremely wide inter- and intra-species ranges in levels of free T₄ and T₃ do not support a previous suggestion, based on temperate freshwater salmonid species, that free T₄ and T₃ levels in fish may fall within a relatively range narrow comparable to that of homeothermic vertebrates.     

Seasonal changes in hepatosomatic index,gonadosomatic index and plasma estradiol‐17β level in captively reared female rabbit fish (Siganus guttatus)

The seasonal changes in hepatosomatic index (HSI), gonadosomatic index (GSI) and plasma estradiol‐17β (E₂) level in female rabbit fish (Siganus guttatus) were investigated. The relationship between plasma E₂ levels with these indices and ovarian growth was also evaluated. Each month, at least 10 female broodfish were sacrificed to collect liver, ovary and blood for HSI, GSI and plasma E₂, respectively. GSI and HSI were calculated as percentage (%) of relative weight of gonad and liver to total body weight, respectively. Plasma E₂ level was measured using enzyme‐linked immunosorbent assay method (ELISA). Ovaries were cut and stained for histological observation. The results included seasonal changes in plasma E₂ levels, stages of ovarian development, GSI and HSI. The highest level of E₂ was observed in June (1,445.62 pg/ml) and during vitellogenesis (2,305 pg/ml). GSI and HSI values significant fluctuated monthly. The highest HSI and GSI were 1.72% in May and 3.58% in June, respectively. The pattern of plasma E₂ levels showed a relationship with GSI and different stages of ovarian development. HSI was associated with ovarian stages. During vitellogenesis, the highest value (1.9%) of HSI was observed. Histological sections showed that rabbit fish is a multiple spawner. These results contribute to further understanding of female rabbit fish reproductive biology in captivity. Important reproductive parameters such as HSI, GSI and E₂ can be used to indicate maturation status of this fish species.     

中国对虾肝胰腺_卵巢及血淋巴中的_省略_雌二醇含量的生殖周期变化

首次证实了孕酮和雌二醇这两种类固醇激素在中国对虾体内的存在.在性腺未发育阶段,肝胰腺、卵巢和血液中两种激素的含量均很低氐,难以检测到.而在卵黄发生前期(核仁周边期),三种组织中孕酮和雌二醇含量迅速上升,卵巢的雌二醇含量达到高峰(450.1±86.7).进入初级卵黄发生阶段,三种组织中,两种激素均具较高含量,卵巢和肝胰腺的孕酮含量(分别为1975 1±175.2和902.6±130.5pg/g)以及血淋巴中的雌二醇含量(451.3±73.7)达到高峰.到了次级卵黄发生阶段,孕酮和雌二醇的含量迅速下降,肝胰腺等组织中儿乎检测不到.对虾性腺指数(GSl)的增长既显著且有规律性,每一期增长幅度都达到或超过l00%.肝胰腺指数(HSI)从性腺未发育期(3.4±04)到卵黄发生前期(4.9±0 7)以及从卵黄发生前期到初级卵H黄发生期(6.3±1.0)有显著的增长,而从初级卵黄发生期到次级卵黄发生期HSI增长不显著(6.7±1.2).肝胰腺指数的增长与两种类固醇激素含量的变化具相似的趋势.上述结果显示,孕酮和雌二醇可能具有刺激和凋控中国对虾性腺发育的作用,肝胰腺可能是卵黄蛋白原的合成场所.     

The effect of vitamin H substitution on the growth and condition of hooves

A long-term treatment with biotin (vitamin H) in 5 warm-blooded horses and 10 trotter horses is reported. The dose of 0.031-0.037 mg/kg body weight was well tolerated, and with a therapy period up to 10 months an improvement of the horn quality of the growing hoof could be attained as it had not been possible before with other measures. Biotin (Gabiotan) is recommendable as a therapeutic in all cases of hoof problems which are based on disturbed horn elasticity.     

复合酶提取法对浒苔(Enteromorpha sp.)膳食纤维吸附能力的影响

针对丰富的浒苔资源还未得到有效利用的现状,以浒苔为原料,采用复合酶提取法制备浒苔膳食纤维。浒苔在55℃、pH=7.7的条件下,由不同比例的蛋白酶和纤维素酶(5:1、10:1、15:1、20:1和25:1)配制的复合酶进行酶解,提取膳食纤维,测定不同提取条件得到的浒苔膳食纤维在模拟体内的环境下(pH=2.0和pH=7.0)吸附葡萄糖、胆固醇和亚硝酸盐的能力。结果显示,随着复合酶中蛋白酶比例的升高,膳食纤维对葡萄糖和胆固醇的吸附能力先增强后减弱。在蛋白酶∶纤维素酶的比例为10:1时,膳食纤维对葡萄糖的最大吸附值为20.03 mg/g;在蛋白酶∶纤维素酶比例为15:1时,膳食纤维对胆固醇的最大吸附值为21.93 mg/g。而浒苔膳食纤维吸附亚硝酸的能力则随着复合酶中蛋白酶比例的升高而逐渐增强,在蛋白酶∶纤维素酶比例为25:1时,浒苔膳食纤维对亚硝酸盐达到最大吸附值29.25 µmol/g。在人工肠液中(pH=7.0),膳食纤维对胆固醇的吸附能力较强;在人工胃液中(pH=2.0),膳食纤维对亚硝酸盐的吸附能力较强;膳食纤维对葡萄糖的吸附能力在人工肠、胃液中无显著差异(P>0.05)。推测膳食纤维对亚硝酸盐的吸附主要发生在胃部,对胆固醇的吸附主要发生在肠部,而膳食纤维对葡萄糖的吸附在胃部和肠部同时进行,是一个持续的吸附过程。     

Isolation and partial characterization of rainbow trout (Oncorhynchus mykiss) gill mucin

Gill mucin from rainbow trout was isolated utilizing two rounds of cesium chloride density ultracentrifugation followed by gel filtration on Sepharose CL-2B. Neither density ultracentrifugation nor gel filtration alone was sufficient for purification of the mucin. Isolated gill mucin had a density of 1.5 g/ml and eluted at the void volume of the Sepharose CL-2B column. Silver-stained reducing 6% polyacrylamide gel electrophoresis of gill mucin produced a band at the origin with a smear entering the separating gel. There was no evidence of a link protein in gill mucin on reducing 12% polyacrylamide gel electrophoresis. Gill mucin had an amino acid profile similar to that of mucins in other species. Specifically, 35.1% of the total amino acids were represented by threonine and serine, while another 27.5% were alanine and proline. Gill mucin contained galactose (26.7 ± 3.2%), galactosamine (22.5 ± 4.4%), glucose (16.6 ± 8.7%), fucose (16.1 ± 1.5%), glucosamine (12.0 ± 1.9%) and mannose (5.1 ± 4.4%). Uronic acid levels from purified mucin were very low (0.7 ± 0.1%). Sialic acid was also present (0.06 g/g of mucin protein). The periodic acid-Schiff assay routinely utilized for detection of mucins was relatively insensitive for detection of gill mucin (6 × less sensitive than for pig gastric mucin) so a rabbit antiserum was raised. The antiserum produced profiles similar to the periodic acid-Schiff assay of fractions following gel filtration. Immunofluorescence of formalin-fixed rainbow trout gill tissue sections showed that the antiserum detected mucin within branchial goblet cells.     

Effects of skeleton photoperiods on melatonin secretion in the rainbow trout, Oncorhynchus mykiss (Walbaum)

Abstract Plasma melatonin levels were measured at hourly intervals in rainbow trout, Oncorhynchus mykiss (Walbaum), maitained under three different skeleton photoperiods: 8L:2D:2L:12D;8L:7D:2L:7D; and 8L:12D:2L:2D. Blood samples were taken before, during and after the 2-h light pulses. Melatonin levels increased rapidly to mean scotophase (dark period) values of 261 ± 7 pg/ml after the first light-dark transition and had returned to mean photophase (light period) values of 51 ± 2 pg/ml 30min after the end of the scotophase. Light pulses during the early, mid- and late scotophase elicited similar reductions in melatonin levels, followed by rapid increases after the light pulse, reaching previous scotophase values within 90 min. The inability of any of the light pulses to modulate or truncate melatonin secretion under a LD 8:16 photoperiod provides further support for the hypothesis that melatonin secretion in the rainbow trout is a direct response to darkness, and is not under endogenous circadian control as in other vertebrates examined.     

Effect of diets containing gossypol on blood parameters and spleen structure in tilapia, Oreochromis sp., reared in a recirculating system

The high cost of fish meal in tilapia diets warrants the potential use of cottonseed meal (CSM) as an alternative source of high quality protein. The effects of varying levels of CSM (0, 25, 50, 75 and 100%) as fish meal protein replacement on growth, blood parameters, spleen characteristics, free and bound gossypol in blood plasma, haemoglobin and haematocrit were determined in tilapia. Gossypol (C(30)H(30)O(8)) is a polyphenolic substance found in cottonseed that has known toxic effects in fish. Tilapias (n = 219, average weight = 11.3 +/- 3.9 g) were randomly distributed into 15, 32-L glass aquaria, representing five dietary treatments and three replicates per treatment. Each aquarium containing 13-16 fish was supplied with thermoregulated, recirculating water (27 +/- 1 degrees C) at 1 L min(-1) flow rate and photoperiod was constant (12 h L/12 h D). Fish fed 25-50% CSM protein replacement showed similar body weights and total lengths as the controls at the completion of the 16-week trial. Fish fed 75 and 100% CSM protein replacement showed a significant decline in body weight and total length. Fish fed 25-100% CSM protein replacement had significantly lower haematocrit and haemoglobin (ANOVA/LSD, P < 0.05) compared with levels in controls. The decline was most prominent in groups fed diets with 50-100% CSM protein replacement. Total and free gossypol concentrations of blood plasma significantly increased with increasing levels of CSM replacement (P < 0.05). No gossypol was found in blood plasma of fish from the control group. The occurrence of immature and abnormal erythrocytes was significantly greater among fish fed 75 and 100% CSM diets compared with fish fed 0-50% CSM diets. Spleen-somatic index (spleen weight/body weight x 100) did not differ between control fish and fish fed 50-100% CSM diets. Spleen abnormalities, such as large depositions of haemosiderin and melanin pigments and proliferation of melano-macrophage centres, lymphocytic depletion of the white pulp areas (hypocellularity), and presence of vacuoles and necrotic areas were observed among fish fed 50-100% CSM protein diets. In general, the pathological effects of gossypol in tilapia (low haemoglobin and haematocrit levels, abundance of immature red blood cells or polychromatocytes, abnormal spleen morphology) were similar to the effects of vitamin E and/or vitamin C deficiencies observed in other studies.     

斑点叉尾对全植物蛋白饲料的胃排空及消化道内容物特性研究

为研究斑点叉尾(鱼回)[体质量(115.55±7.54)g]对全植物蛋白饲料的胃排空,实验比较了3种常用数学模型对其排空曲线的拟合程度,同时探究了摄食过程中消化道内容物的水分、pH和消化酶的变化规律.结果发现,3种数学模型均可较好地描述斑点叉尾(鱼回)胃排空曲线,平方根模型最适于定量描述,指数模型次之,线性模型较差.根据平方根模型分别计算得到斑点叉尾(鱼回)胃50％排空时间为12.8 h(以干重计),完全排空约36 h.在摄食后0～36 h内,内容物水分含量在后肠保持不变,在胃部呈缓慢上升趋势,而在前肠和中肠则呈先上升后下降趋势.消化道各段内容物pH在摄食后3h内均显著下降,3～30 h间总体保持平稳状态,在30 h后又呈显著上升趋势.消化道各段蛋白酶、脂肪酶和淀粉酶比活力在摄食3h内显著上升,并在3～30 h内保持相对稳定水平,摄食30 h后呈显著下降趋势.整个摄食过程中,消化道各段消化酶比活力大小依次为前肠＞中肠＞后肠＞胃.研究表明,斑点叉尾(鱼回)在摄食过程中,消化道各段内容物的水分、pH和消化酶比活力均随时间呈现相应的规律性变化.而这些内环境参数的相互作用,综合影响了特定胃排空时间的形成.     

Gastric dilation and air sacculitis in farmed chinook salmon, Oncorhynchus tshawytscha (Walbaum)

A syndrome affecting cultured chinook salmon, Oncorhynchus tshawytscha (Walbaum), characterized by distended abdomens, gastric dilation, air sacculitis (GDAS), increased feed conversion rates and increased mortality has been recognized in New Zealand. Affected fish were most obvious in sea cages but were also present in fresh water. Mortality rates associated with this condition were highest in late summer and approached 6% per month. A dilated and flaccid stomach, without visible rugal folds containing copious oil, watery fluid or undigested feed was typical. Gastric mucosal ulceration or inflammation were not present. The air sacculitis consisted of a thickened, dilated bladder with a mixed mucosal inflammatory infiltrate and a luminal exudate associated with large numbers of morphologically diverse bacteria. Gastric dilation or air sacculitis occurred alone or together in the same fish. In a group of 20 subclinically affected fish with or without gastric dilation, there were no significant differences in weight, length, serum osmolality, sodium, total protein or packed cell volume. Twenty-three severely affected fish had significantly ( P  < 0.05) higher serum osmolality but similar sodium and total protein to that of clinically normal fish.