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Pathological investigations of gentamicin toxicity in commercial layers
Muhammad Kashif Saleemi1. Muhammad Zargham Khan1, Ahrar Khan1, Najam Ul Islam3 Zahoor-ul-Hassan 1& Rao Zahid Abbass2 1Department of Pathology, 2Department of Parasitology, University of Agriculture Faisalabad, Pakistan. 3Department of Livestock and Dairy Development Toba Tek Singh Pakistan. Pathological investigations of gentamicin toxicity in commercial layers
Abstract
Gentamicin is an antibiotic belonging to aminoglycoside groups of antibiotics. It is used to treat different bacterial infections in avian species. It is highly effective through parenteral route but it is highly toxic and excreted from body very slowly. In the present different cases of clinical gentamicin toxicity in commercial layers were observed and recorded. Gentamicin is lavishly used in Pakistan in poultry trough parenteral routes because of its higher clinical efficacy and economics. In first case gentamicin was injected seven times at dose rate of 10 mg/kg bodyweight (BW) during a period of 9-15 weeks. The mortality was 9%. In second case gentamicin was injected at dose rate of 25 mg/kg BW, four times during 2 weeks period and mortality was 83 %. In third case gentamicin was injected thrice at a dose rate of 22.22 mg/kg BW in 20-21 weeks of age and mortality was 72%. In all three cases birds were dehydrated, emaciated with prominent keel bone. Clinical sing of dehydration, decreased bodyweight gain, decreased feed intake, increased water intake and watery diarrhea were observed before death. Necropsy examination of dead birds indicated swollen liver, enlarged kidneys bulging out from bony sockets. Petechial hemorrhages were present on heart and skeletal muscles. Microscopically hemorrhages and acute tubular necrosis was observed throughout the renal parenchyma. In liver hemorrhages, cellular infiltration, biliary hyperplasia and vacuolar degeneration of hepatocytes was observed. From above findings it was concluded that repeated administration and higher doses of gentamicin lead to toxicity and high mortality in birds. Key words: Gentamicin, Toxicity, Layers, Pathological, Bodyweight, Feed intake, Hemorrhage Introduction
Gentamicin is an important therapeutic agent used in poultry and animals belonging to aminoglycoside group of antibiotics. It is used in poultry birds for the treatment of different diseases e.g. collibacillosis, salmonellosis etc. (Giurov, 1985 and Giurov, 1986). In Pakistan gentamicin is used through parental routes because it is very economical and effective in injectable form. It is used in combination with tylosin and lincomycin and other antibiotics. It is also administered along with hydropericardum vaccine in broiler and layers to prevent bacterial contaminations (Khan et al., 2008) .Gentamicin in many regions of the world is unofficially used in day old birds to prevent early chick mortality (Saleemi et al., 2009). Its long standing retention in body tissues for 45 days in muscles and 75 days in liver of turkey birds makes it use questionable in birds intended for human consumption (Shem Tov et al., 2003).Experimental gentamicin toxicity has been studied in day old broiler chicks by (Saleemi et al., 2009) and no observable effect level (NOEL) of single intramuscular injection of gentamicin was 10 mg/kg bodyweight. However (Khan et al., 2008) found two intramuscular injections of gentamicin at days 1 and 3 were safe. It is also used in human for the treatment of different eye and ear infections in the form of either ointments or eye/ear drops. Its lavish use in humans leads to ototoxicity and ultimately deafness. In layer birds it is used repeatedly to treat the different bacterial infections, its continuous use lead to nephrotoxicity and high mortality. In this particular field study , these untoward effects of gentamicin in commercial white leghorn layer Cases History
In the first recor3ed case a commercial layer flock at growing stage (age:12 week) was effected with gentamicin by overdosing at Vehari district of Punjab. A total of 9000 W-36 commercial white leghorn layer were kept and early chick mortality was 10%. At week 5 gentamicin + Bacolam (Amoxicillin + Colistin) was injected intramuscularly at a dose rate of 10 mg/kg bodyweight three times on alternate days. Then after three weeks interval again gentamicin + Bacolam (Amoxicillin + Colistin) was injected for four times on alternate days. During this period of two months gentamicin was injected 7 times, mortality record is described as follows Post Gentamicin Injection Mortality
Mortality #
Mortality %
In second case 17th week old commercial layer pullets were injected with gentamicin four times at dose @ 25 mg/kg b.w . Total flock size was 7500 commercial white leghorn layer. Total Post Gentamicin Injection Mortality
Mortality #
Total Mortality
In third case reported from Syedwala district Sheikhupura area of Pakistan. A total of 16000 commercial white layer was injected with 10 % gentamicin at dose @ of 1ml/3birds (33.3 mg gentamicin /bird) at 20th week of age. W Gentamicin was injected three times on alternate days at above mentioned dose. Mortality started after three weeks of injection. Maximum mortality was in week 26th and total mortality was 71.85%. The weekly mortality of five weeks is described in Post Gentamicin Injection Mortality
Mortality #
Total Mortality
11497/16000
Necropsy and Histopathology
The postmortem examination of dead birds was performed, gross lesions on different organ were recorded and different tissues including liver and kidneys were collected and preserved in 10% neutral buffered formalin and processed for histopathological examination by paraffin embedding method. Five micron thick sections were cut and stained with hematoxylin and eosin Gross lesions/findings/pathology
In all three cases birds were depressed, emaciated and dehydrated with prominent keel bone. On postmortem examination kidneys were, hemorrhagic, swollen and bulging out from bony socket. The crystals of uric acid were deposited in the kidneys. Liver was also swollen, hemorrhagic and friable having light and dark color streaks on its surface. A specific lesion was noticed in many birds of typical blood clot along with pinpoint hemorrhages was present on epicardial surface of Histopathology
In the kidneys epithelial cells of convoluted tubules showed pyknotic nuclei indicating acute tubular necrosis. At few places congestion was also present in renal parenchyma. In some birds these changes were more severe involving extensive areas of necrosis. Glomeruli were congested having pinkish material. Urinary space was not clear having pinkish material. In liver vacuolar degeneration was present, having vacuoles of different sizes. Individual cell necrosis of hepatocytes was also present. The congestion was present throughout the parenchyma of liver. At few places cellular infiltration was also present. Discussion
There is a little information available about toxicopathological effects of gentamicin in laying birds, however information is available about pathological effects of gentamicin in day old broiler chicks (Saleemi et al., 2009) and growing broilers ( Javed et al., 2008). In present study in first case gentamicin was injected thrice with one week interval at dose rate of 10 mg/kg body weight then after three weeks again gentamicin was injected four times at dose rate of 15 mg/kg bodyweight. But exciting thing is that both times it was injected in combination with Bacolam (a preparation containing Amoxicillin and Colistin). However Khan et al (2008) reported that two injections of gentamicin at dose rate of 10mg/kg bodyweight are safe, but in present clinical study dose rate was higher and it was injected seven times during two months period. In second case gentamicin was injected relatively at higher doses 25mg/kg bodyweight during two weeks interval and mortality was 82.74%, mortality started three weeks after the injections and continued upto five weeks. In third case gentamicin was injected intramuscularly dose rate of 33.3 mg/kg bodyweight thrice and mortality was 71.85 %. In all three cases in the present study mortality was dose dependant. In present studies dead birds showed acute tubular necrosis in kidneys and congestion of renal parenchyma. In liver vacuolar degeneration, individual cell necrosis and moderate congestion were consistent findings in all three cases. Similar results have been presented by Khan et al (2008) and Saleemi et al (2009) in WL commercial layers and day old broiler chicks in experimental studies. Similar to our findings tubular necrosis has been reported by many authors in different species in gentamicin toxicity, including rats (Hottendorf and Williams, 1986, dog (Grauer et al., 1994), cat (Mealy and Boothe, 1994) and poultry (Khan et al., 2008 and Saleemi et al., 2009).However in present study changes are more severe as compared with previous studies, it may be due to higher and repeated doses of gentamicin. In present cases another novel finding was hemorrhagic lesions on epicardial surface and this was consistent feature, no such lesions have been reported by previous workers. It has been concluded from findings of present study and previous experimental studies that gentamicin toxicity starts after three weeks and continued upto five weeks. It is suggested that gentamicin should not be injected repeatedly and its lavish use should be avoided. References
Giurov B, 1985. Sensitivity of Escherichia coli strains isolated from poultry with coli septicemia. Giurov B, 1986. Drug sensitivity of Salmonella strains isolated from poultry in 1980-1984. Vet Grauer GF, DS Greco, EN Behrend, MJ Fettman, RS Jaenke and TA Allen,1994. Effect of dietary protein conditioning on gentamicin nephrotoxicosis in healthy male dogs. Am J Hottendrof GH & PD Williams, 1986. Aminoglycoside nephrotoxicity.Toxicol Pathol,14: 66-72. Javed U, MK Saleemi, MZ Khan, A Khan and I Javed,2008. Pathological effects of gentamicin in growing broilers. Pp: 017-018. (Proceedings, the 15th Congress of FAVA-OIE Joint Khan I, MZ Khan, MK Saleemi, I Javed and A Khan, 2008. Pathological and biochemical effects of intramuscular gentamicin administration in chicken. Turkish. Journal of Veterinary Mealy KL, DM Boothe, 1994. Nephrotoxicosis associated with topical application of gentamicin in a cat. J Am Vet Med Assoc, 204: 1919-21. Shem-Tov M, N Gabor, M. Suth, P Kormoczy, 2003. Depletion of gentamicin and its major components from various tissues of turkeys. Am J Vet Res, 64:1234-36. Saleemi MK, MZ Khan, A Khan and I Javed, 2009. Pathological effects of gentamicin administered intramuscularly to day old broiler chicks. Exp Toxi Path,61: 425-432.

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