Pathogenesis of infectious bronchitis nephritis. 2 ...

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Avian Pathology

ISSN: 0307-9457 (Print) 1465-3338 (Online) Journal homepage: http://www.tandfonline.com/loi/cavp20

Pathogenesis of infectious bronchitis nephritis. 2. Studies of water and electrolyte balance in colostomised chickens R.J. Condron & A.T. Marshall To cite this article: R.J. Condron & A.T. Marshall (1985) Pathogenesis of infectious bronchitis nephritis. 2. Studies of water and electrolyte balance in colostomised chickens, Avian Pathology, 14:4, 509-520, DOI: 10.1080/03079458508436253 To link to this article: http://dx.doi.org/10.1080/03079458508436253

Published online: 02 Jan 2008.

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Date: 30 January 2016, At: 16:10

Avian Pathology, 14: 509-520, 1985

PATHOGENESIS OF INFECTIOUS BRONCHITIS NEPHRITIS. 2. STUDIES OF WATER AND ELECTROLYTE BALANCE IN COLOSTOMISED CHICKENS R.J. CONDRON1,2 and A.T. MARSHALL3 Downloaded by [187.95.90.19] at 16:10 30 January 2016

1

Veterinary Research Institute, Department of Agriculture, Parkville, Vic. 3052, Australia. 3

Department of Zoology, LaTrobe University, Bundoora, Vic. 3083, Australia.

SUMMARY Water and electrolyte balance was examined throughout the course of an experimental infection with T strain infectious bronchitis virus in colostomised chickens. Significant losses of water and negative sodium and potassium balances were observed. The major change in the electrolyte balance was the increased output of sodium in urine and this was associated with a diuresis. A decrease in food intake was the most important contribution to the negative potassium balance. Death resulted from acute renal failure. The implication of the results for electrolyte replacement therapy is discussed and a method for colostomies in birds weighing less than 0.5 kg is described. INTRODUCTION Infectious bronchitis virus (IBV) produces a nephritis in chickens (Winterfield and Hitchner, 1962; (Humming, 1963; Julian and Willis, 1969). This is an economically important disease in Australia and many factors such as cold stress, nutrition, age and sex of the chicken influence the severity of the disease (Cumming, 1965; Sinkovic and Gilchrist, 1967; Macdonald et al., 1980). Those strains of the virus which induce more severe kidney disease are also associated with higher mortality rates (Siller and Cumming, 1974; Chong and Apostolov, 1982). Histological investigations of the development of kidney lesions throughout the course of experimental infections have shown interstitial inflammatory reactions and tubular degeneration (Siller and Cumming, 1974; Pohl, 1974; Purcell et al., 1976). In a morphometric analysis of the ultrastructural changes in the proximal Received 10 May 1985 Accepted 9 July 1985 2 Address for Correspondence: Dr R.J. Condron, Veterinary Research Institute, Department of Agriculture, Parkville, Vic. 3052, Australia.

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tubular epithelium following infection with IBV, Condron and Marshall (1985) found a reduction in the functional components of the cells. The surface area of membranes was decreased and there were changes in mitochondria, including a reduction in the volume density.

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Heath (1970) investigated biochemical aspects of the pathology of infectious bronchitis nephritis and found birds had negative sodium and potassium balances. The deaths of the chickens were attributed to kidney dysfunction and acute renal failure. In order to assess the contribution to overall fluid and electrolyte balance of changes in kidney function compared with changes in alimentary tract function, it is necessary to collect and analyse faeces and urine separately. This paper describes an investigation of water and electrolyte balance of colostomised IBVinfected chickens. MATERIALS AND METHODS Experimental birds Webster-Mini crossbred chickens were raised in specified pathogen free (SPF) facilities from SPF eggs supplied by the Commonwealth Scientific and Industrial Research Organisation, Animal Health Division. Regular monitoring and serological testing has shown the birds from this isolation unit to be free from a wide range of viral, bacterial and mycoplasma agents. The chickens were fed on a fibre-free diet composed of 53% dextrose, 5% casein, 11% torula yeast, 14.5% soya protein, 7.5% cellulose, 4% maize oil and with supplementary amino acids, salts, vitamins and minerals until 4 weeks of age when a colostomy was performed. The birds were kept in separate cages and 3 days after surgery an irradiated commercial chick crumble diet (18% crude protein, 0.17% sodium and 0.50% potassium) was gradually introduced to the fibre-free diet. At 7 days following the colostomy the diet was 100% chick crumbles. Surgical procedure The technique used to create an artificial anus was a modification of the method described by Tao etal. (1969). The chickens were anaesthetised with ether and two incisions were made. One extended for 2 cm anterior to the cloaca in the midline and the second, 0.7 cm in length, was made in the right lateral abdominal wall. The colon was divided and the cloaca was closed by access through the midline incision. The anterior section of the colon was passed through the lateral incision. The colon was fastened to the peritoneum and muscle layers with four sutures through the serosa and muscularis and the everted end of the colon was sutured to the skin using 4/0 chromic gut. Crystalline penicillin powder was placed in the abdominal cavity and tetracycline and neomycin (Neo-Terramycin 25/25, Pfizer) were administered in the water for 1 day before and 4 days after surgery. Plan of experiment Eight days after the colostomy the chickens were weighed and the collection of all faeces and urine was commenced. Plastic vials were held over the artificial anus and the cloaca by attaching the screw tops of the containers to a many-tailed cotton harness. The containers were changed four to fives times daily. The quantity of faeces and urine was measured and the samples were then stored at -20PC for subsequent analysis. Chick crumbles and distilled water were available ad lib. and the amount consumed was measured and replenished twice daily.

Water and electrolyte balance in IB nephritis

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After 3 days monitoring total intake and faecal and urine output, IBV was administered to a group of six chickens. A volume of 0.5 ml of a suspension of the "F strain of IBV (Winterfield et al., 1964) in allantoic fluid was injected intravenously and 10 jul was inoculated into both conjunctival sacs of each bird. The virus, which was obtained from Dr T. Faragher, National Biological Standards Laboratory, Parkville, Victoria, was passaged once and the allantoic fluid which was harvested 48 hours after inoculation of 10-day-old embryonated (SPF) eggs had a titre of 3 x 104 EID 50 P e r ml in subsequent egg inoculation studies. Two uninoculated control birds, with colostomies, were kept in complete isolation from the infected birds. The food and water intake were measured and all faeces and urine were collected from each bird for a further 9 days or until the bird died. Autopsies were performed on all birds. Analysis of specimens Samples of urine, faeces and food were digested with concentrated nitric acid and the sodium and potassium concentrations were determined by flame-photometry. Chloride concentration in urine was measured using a Chloride meter (model 920, Coming-Eel). Uric acid was determined by the UV absorption-uricase digestion method (Praetorius et ah, 1953). Urine was initially diluted 1 in 100 in glycine buffer to dissolve the precipitated fraction and the diagnostic Uric Acid Test Kit and Standards (Boehringer Mannheim) were used. Dipsticks (Combur, Boehringer Mannheim) were used to measure urine pH and test for glucose. Values of total daily water and electrolyte intake and output were determined and ratios of the different components of electrolyte balance were calculated in order to assess their relationships and their contribution to changes in the overall electrolyte balance. A paired t-test was applied to the ratio of mean daily values for infected chickens 3 days before and 3 days after inoculation with IBV. In this test each bird acted as its own control. In order to allow for the effect of colostomy with time a further t-test was used to compare the mean daily values for the noninfected control chickens with mean daily values for the infected chickens, during the same four days following IBV inoculation. RESULTS All chickens recovered successfully from the colostomy operation. When faecal and urine collections were commenced the wounds had healed and the birds passed faeces and urine normally. At this time the mean body weight of control birds and birds which were subsequently infected was 439 and 436 g respectively. All birds had increased in body weight at the time of IBV inoculation and the mean body weights were 458 and 454 g. Following infection with IBV the chickens showed typical signs of infectious bronchitis. The birds became depressed and had loss of appetite. Coughing, bronchial rales and weight loss were observed. The mean body weight 3 days postinfection was 425 g compared with the controls, 485 g. All the infected chickens died within 4 to 9 days after inoculation and they had lesions of infectious bronchitis nephritis. The mean body weight of infected birds on the day of death was 368 g. The control birds had a mean body weight of 472 g at the end of the experiment. In the 12 hours preceding death, the urine output of infected birds decreased dramatically and there was a marked increase in electrolyte and uric acid concentrations, consistent with acute renal failure. At autopsy the infected birds were

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dehydrated and the ureters were distended with urates. Histologically, there was an interstitial nephritis with primarily a mononuclear inflammatory infiltration and there was evidence of tubular degeneration. The non-infected, colostomised, control chickens were healthy at the end of the experiment and there was no evidence of kidney lesions.

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A summary of the total water and electrolyte balance is shown in Table 1. All infected birds had negative sodium and potassium balances and a significant reduction in both sodium and potassium retained was demonstrated. Infected birds also retained less water compared with values for the non-infected controls. The change in daily sodium and potassium balances with time is depicted in Text-figs. 1 and 2. After an initial decline in electrolytes retained by both groups, the control birds maintained or returned to a positive balance whilst the infected birds continued in negative balance. Table 1. Daily water and electrolyte balance of IBV-infected colostomised chickens (mean ± i.e. mean) Control

Sodium retained (mmol) (intake-output) Potassium retained (mmol) (intake-output) Water retained (ml) (intake-output) Statistical analysis

1. 2.

P valuea

Infected

All chickens prior to infection day -2 to 0 (n=8)

Non-infected control chickens day 1 to 8 (n=2)

Infected chickens

1

2

.995 ± .085

.684 ±.109

-.094 ± .222

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