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ThesisItem Open Access Pathology of hypothyroidism in pigs(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences,Mannuthy, 1995) Prasanna, K S; KAU; Sreekumaran, TAn experimental model of hypothyroid state was induced in piglets, using thiourea with the objectives of studying the sequence of clinico pathological changes and its influence on the animal health and growth. Tweleve Large White Yorkshire male piglets of 2 – 3 months age were selected for the study. The animals were divided into control group of six animals and experimental group of six animals. Experimental hypothyroidism was induced by feeding thiourea daily for a period of three months at the dose level of 50 mg per kg body weight. Haemogram, body weight, plasma proteins, serum cholesterol and serum thyroxine values were estimated at periodic intervals. The piglets were subjected to detailed autopsy after sacrifice. Gross lesions were recorded and detailed histopathological examination of tissues was carried out. During the course of experiment all the experimental animals recorded stunted growth and appreciable reduction in feed intake and alopecia of neck and shoulder regions. There was significant increase in blood cholesterol values and plasma protein level in thiourea fed group. A significant reduction in serum thyroxine level was also recorded. There was significant increase in the relative weight of thyroid, adrenal and pituitary glands of experimental animals. Gelatinisation of subcutaneous fat and dilatation of right ventricles were common findings at autopsy. Histologically the thyroid glands exhibited varying degree of hyperplastic changes and depletion of colloid in the follicles. Hyperplasia and hypertrophy of the lining epithelium was also observed. Predominant histological changes in the pituitary was hyperplasia and hypertrophy of the basophil cells and degranulation of the acidophil cells. Adrenal glands showed diffuse hyperplasia of zonafasiculata and accessory cortical nodule formation. Skin revealed acanthosis, hyperkeratosis and keratinisation of harifollicles. In all the hypothyroid animals testis showed varying degree of tubular degeneration. A random survey study was conducted to assess the thyroid status of pigs from different parts of Kerala using serum thyroxine as the marker. This concluded that most of the animals had the normal range of serum thyroxine levels.ThesisItem Open Access Pathology of the Harderian Gland in chicken and duck(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences,Mannuthy, 1998) Mohan S; Valsala K VThe lymphoid tissue of the upper respiratory tract includes paraocular and paranasallymphoid structures as well as some lymphoid accumulations in the pharynx and larynx. However, of all these paraocular lymphoid tissue, the Harderian gland is highly immunopotent. The role of the Harderian gland in the immunopathological response was evaluated taking chicken and duck as models and RD, IBD and Duck plague vaccines as antigens. The sequential cellular response following ocular antigenic stimulation was clarified. Significant increase in the plasma cell number, enlargement of the lymphoid foci and Russell body formation following ocular antigenic stimulation were the hall marks of the immune response of the Harderian gland of the chicken but this was not so much significant in the case of ducks. Harderian gland was highly reactive especially in the chicken but not so much in the case of ducks. Intraocular vaccination was found to be comparatively more effective in immunological protection in chicken. It would therefore, appear that through local administration of the antigen at the Harderian gland the duck may not respond in the same way as in the case of chicken. It was pointed out that the local antibody produced by the Harderian gland contributed in a major way to the immunological defence at the oculonasal and oropharyngeal areas and it has an obvious relevance to the epidemiology and the control of respiratory viral diseases in the avian species.ThesisItem Open Access Prevalence and patholoygy of polioencephalomalacia in goats(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences,Mannuthy, 1999) Divakaran Nair N; Rajan APolioencephalomalacia (PEM) is a significant emerging diseases problem in goats. Although, PEM in goats was recognized and reported as early as 1956, its etiology is poorly understood and symptomatology, pathological features and therapeutic approach have not been well defined and documented. Hence an investigation was undertaken to assess the prevalence of the disease based on the data available from 76 Veterinary hospitals of the state for a period from 1991 to 1994. This data documented revealed an increasing trend in the occurance of the disease and significantly high incidence was recorded in the first five months of which the peak incidence was observed in the month of April. Spontaneous cases of the disease were studied in detail and experiments were conducted taking goat as a model using selected incriminating agents such as Amprolium (350mg/kg body weight), Amprolium and rice gruel (350 mg/kg and ad libitum rice gruel), rice gruel (ad libitum), sodium sulphate (150 mg/kg body weight followed by 500 mg/kg body weight on the 10th day) BHC (2.5 mg/kg followed by 5 mg/kg body weight on the 10th day) and Ficus tsiela Roxb. The experiment was for a period of 45 days. Symptomatology, weight of the animals at fortnightly intervals, weight of the brain, CSF protein concentration, brain autofluorescence, gross and histopathological alterations of the brain and ultrastructural pathology were the markers utilized for evaluating the disease processes. The sodium sulphate, BHC and Amprolium and rice gruel treated group showed symptoms and lesions more or less similar to the spontaneous cases. Only few animals in each group developed the disease such as two in amprolium and rice gruel treated group, four in BHC treated group and three in sodium sulphate group. This showed that individual idiosyncracy plays an important role in the manifestation of the disease. The symptoms developed at different latent periods were not progressive as compared to the spontaneous cases where the symptoms were progressive. The symptoms included lethargy, depression, knuckling at the fetlock, frequent tremors, opisthotonous and loss of eye preservation reflex. Blindness was seen in one of the natural cases. The histological lesions of the brain in all the cases were comparable in different segments of the brain. Mostly it was characterized by diffuse laminar cortical degeneration and necrosis, occasional neuronal swelling glial cell reaction and white matter vacuolation. Vascular changes predominated in the sodium sulphate group and also in the natural cases. There was glial cell response in the form of nodules in sodium sulphate group and natural cases. A predominant perivascular and neuropil accumulation of lymphocytes, gitter cells and monocytes were seen in the natural cases. These were considered as secondary deposition following a toxic degenerative neuropathy. The necrotic focicould well be delineated in few of these cases by the bluish or creamy autofluroscence of the affected brain, but was not found to be of any primary diagnostic value as all the affected brain did not show flurescence. Ultrastructural investigation revealed the basic reaction of the brain tissue to be similar in both the experimental and natural cases except for their intensity. Ultrastructural lesions were characterized by neuronal swelling, membrane lysis, segregation of the filamentous and granular component of nucleolus, cytoplasmic oganellar damage such as fragmentation of RER, partial degranulation of ribosomes, mitochondrial of RER, partial degranulation of ribosomes, mitochondrial swelling, cristolysis and complete disappearance of organelle. Neuropil spongiosis and splitting of myelin at the intraperiod line and formation of multiple vacuolations of the white matter were characteristic. From this observations it was clearly delineated that the primary insult was a biochemical one which caused much damage to the volume control mechanism of the cell and subsequent cellular damage. The CSF protein evaluation revealed high protein level in the spontaneous cases whereas in the experimental cases, the concentration remained within the normal range indicating that it has no diagnostic value. In this investigation it has not been possible to induce PEM with Amprolium even at a dose rate of 350 mg/kg bodyweight and it was proved that amprolium is not a cause for PEM. Rice gruel ad libitum was found to be tolerated by the animal except one which showed dullness and abdominal distension towards the end of the experiment. Diffuse neuronal degeneration was observed in the brain of this animal. Based on this observation it was concluded that rice gruel consumption every day as a component of the concentrate feed in goats might not cause any detrimental effects and the problem comes only when it is fed in large quantities on a single day. Ficus tsiela Roxb. Though produced vascular damage and diffuse neuronal degeneration in one of the experimental animals, goats were found to be highly resistant to ficus tsiela Roxb. Toxicity and the variation in the susceptibility of different species to this toxicity was brought to light. From this investigation it was also clarified that sodium sulphate, BHC, rice and amprolium could be initiating agents of PEM under certain circumstances and no single cause seems to be responsible for PEM.ThesisItem Open Access Determination Of Permissible Level Of Aflatoxin In Broiler Chicken Feed(Department of Pathology, College of Veterinary and Animal Sciences,Mannuthy, 1999) Arulmozhi A; KAU; Koshy VargheseThe study was undertaken to assess the effect of various levels of aflatoxin on the performance of broilers and to establish the permissible level of aflatoxin in the broiler feed. One hundred and eighty day old broiler chicks were divided into six groups of 30 birds each and were given feed containing graded levels of aflatoxin at 0, 20, 40, 60, 80 and 100 ppb for a period of 45 days. Feed intake, weekly body weight gain, feed efficiency, haemogram, serum profile, organ weight, residual aflatoxin in tissues and pathological changes in liver, kidney, bursa and spleen were studied at fortnightly intervals to evaluate its dose related effects. A dose dependent decrease in the daily feed intake and mean body weights were noticed in all the groups. The cumulative FeR was extremely poor at 80 and 100 ppb levels at sixth week of age. The toxicopathological changes in the birds varied in its intensity in relation with the level of aflatoxin in the feed, with most severe changes being at higher dose levels. The values of haemoglobin, PCV, total leucocyte count, Iymphocytes, total serum protein and albumin showed a decrease whereas the ESR, heterophil and serum enzyme were increased. The aflatoxin, even at 20 ppb levels caused degenerative and necrotic changes in liver and kidneys and the intensity of the lesions increased with higher levels of toxin. Attempt for regeneration and repair processes were well pronounced by the 30th and 45th day. Lymphoid depletion was a characteristic feature in bursa and spleen. Degeneration and lysis of lymphocytes with cys; formation was also seen in bursal follicles. Residual aflatoxin was detected in the liver and muscle in all groups by the 45th day. The net returns from the toxin treated birds showed a dose related decline compared to control and the loss in profit at 20 ppb level was marginal About 24 per cent of the poultry feed samples tested during the period from January to July 1999 were contaminated with aflatoxin quantitatively ranging from 20 to 200 ppb. The results of the present study shows that even at 20 ppb aflatoxin causes cellular and subcellular damage to the tissues. However, the economic loss at this level was marginal when compared to higher dose levels. Hence 20 ppb can be considered as permissible level in broiler chicken feed.ThesisItem Open Access Immunopathologic and toxic effects of endosulfan in chick embryo(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 2004) Kalai Selvan, P; KAU; Divakaran Nair, NThe present study was undertaken to investigate the immunopathologic and toxic effects of endosulfan in chick embryo. The embryos were exposed to endosulfan at various dose levels through different routes. The weight of the embryo, bursa, thymus and spleen, histopathology of the lymphoid organs, liver, kidney and brain and quantification of the preformed maternal IgY level in the egg yolk were the parameters analysed to study the effects. Endosulfan was found to be teratogenic at the grven dose levels. The abnormalities observed were agenesis of beak, crossed beak, short lower beak, eventration of viscera and curled toe. Endosulfan did not cause any significant gross changes in the developing embryos except mild haemorrhages. Endosulfan treatment did not produce any significant reduction in the weight of the embryos as well as the weight of the lymphoid organs. On histopathological examinations endosulfan was found to be nephrotoxic and hepatotoxic to the embryos. Varying degrees of degeneration and necrosis was evident in kidney and liver. Effect on the bursa, thymus and spleen were mild to moderate where in the degenerative changes predominated. Dose dependent increase in the involution process of the thymus as evidenced by increase in the Hassal's zone was observed. The lesions in the developing lymphoid organs reflected that endosulfan is toxic to the system and going to affect the immunocompetency by way of immunosuppression and thereby rendering the chicks susceptible to various diseases. The study indicated that the endosulfan treatment did not have any effect on the preformed maternal immunoglobulin level in the egg yolk.ThesisItem Open Access Pathology of cardio-pulmonary disorders in canines(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 2003) Pradeep, M; KAU; Vijayan, NThe present study was undertaken to assess the prevalence and pathology of various cardiac and pulmonary disorders in dogs. The data collected from the autopsy records maintained at the Centre of Excellence in Pathology, Mannuthy and seventy eight samples of heart and lungs from necropsy cases formed the basis of the study. Ninety nine per cent cases showed varying types of cardiac and pulmonary lesions. The highest incidence in the heart was dilated (75.32 per cent) and hypertrophic (15.58 per cent) cardiomyopathies. The other lesions found were hydropericardium, cardiac tamponade, haemorrhage, myocarditis, endocarditis, endocardial fibroelastosis, valvular blood cyst coronary arteriosclerosis and mural. thrombus. Myocardial infarction was found to be confined to the left ventricles and interventricular septum in all the encountered cases (5.19 per cent). Pulmonary congestion (70.51 per cent), haemorrhage (32.47 per cent) and edema (31.17 per cent) were observed with higher incidence rate. The other lesions found in the lungs were bronchitis, emphysema, pneumonia, collapse, infarction, mineralization, ossification, anthracosis and endarteritis obliterans. Metastatic osteosarcoma in the lungs, metastatic lymphosarcoma in the heart and lungs were also observed. The incidence of cardio-pulmonary disorders encountered was relatively high. The need and scope for investigation into the pathological disorders of the heart and lungs of canines were highlighted.ThesisItem Open Access Pathology of the prostate gland in dogs(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences,Mannuthy, 2004) Dhanya Menon, KAU; Vijayan, NThe present investigation was undertaken to evaluate the prevalence and nature of pathological conditions of the canine prostate. A detailed systematic examination of 100 carcasses brought for autopsy during the period of investigation was conducted and the gross and histopathological lesions were studied in detail. The study confirmed prostatic disorders as an age related problem and also warned that involvement of the prostate in concurrent pathological affections of the urogenital system should not be overlooked. Heavy breeds like the German shepherds were found to be the most susceptible to prostatic diseases. An age related increase was also seen in the prostatic weight, circumference and length. Prostatic lesions could be encountered in 49 per cent of the cases. The most common prostatic disease encountered in this study was benign prostatic hyperplasia followed by prostatitis, prostatic atrophy, prostatic adenocarcinoma and squamous metaplasia. Glandular, cystic and complex types of hyperplasia could be observed. The identification of prostatic adenocarcinoma in a castrated dog pointed to the necessity to study the role of extra gonadal sex hormones in prostate carcinogenesis. Escherichia coli and Klebsiella sp. were isolated from cases of prostatitis. Acid phosphatase activity was more for hyperplastic and neoplastic prostates when compared to the normal prostate. This indicated that prostatic acid phosphatase could be used as a marker for the diagnosis of canine prostate cancer both by impression smears and cryostat sections.ThesisItem Open Access Gastrointestinal and neurotoxic effects of cypermethrin in rats(Centre For Excellence In Pathology, College of Veterinary and Animal Sciences, Mannuthy, 2008) Remya Nair, R; KAUThe present study entitled ‘Gastrointestinal and neurotoxic effects of cypermethrin in rats’ was undertaken to investigate the potential toxic effects of cypermethrin in rats with particular emphasis on its effect on the nervous and digestive system.The clinical signs, gross pathology, histopathology, haematology and biochemical parameters were analysed to study the effects. Cypermethrin was found to be neurotoxic and gastroenterotoxic at the given dose levels. Oral administration of cypermethrin in medium and high doses produced nervous signs in animals. However cypermethrin did not cause any significant variation in the body weight of animals. All haematological parameters evaluated showed a dose dependent reduction in its value. Biochemical parameters assessed revealed hepatotoxic and multisystemic effects of cypermethrin. Gross lesions observed in the intoxicated groups were bloat, congestion of lungs, heart, brain, pulmonary haemorrhage and degenerative changes in liver and kidneys. On histopathological examination, cypermethrin was found to be neurotoxic, hepatotoxic, enterotoxic, pneumotoxic, cardiotoxic and nephrotoxic as evidenced by varying degrees of degeneration and necrosis in various organs examined. Effects on all organs were mild to moderate degenerative changes at the low dose level. Medium and high dose intoxicated groups revealed necrotic changes, extensive haemorrhages, congestion in organs like liver, kidney and lungs apart from the changes observed in low dose group animals. Haemodynamic disturbances were manifested in the forms of congestion and haemorhages in lungs, heart, liver and kidneys. The histopathological evaluation revealed no cypermethrin induced toxic effects on the oesophagus. Spinal cord lesions were observed only in the lowest dose group. Brain lesions were only degenerative changes. These findings suggested that biochemical effects rather than structural changes were involved in toxicity.ThesisItem Unknown Hepato-renal pathology in canines(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 2001) Lakshmi, R; KAU; Koshy VargheseThe present investigation was undertaken to assess the prevalence and pathology of the liver and kidney disorders in canines. The results of the present investigation and the evaluation of data from the records revealed a high incidence of liver (76 percent) and kidney (85 per cent) disorders. A detailed systematic examination of one.hundred cases of canine carcasses brought for autopsy during the period of investigation was conducted and the gross and histopathological lesions were studied in detail and were classified based on age, sex and breed. Vascular and degenerative changes were the predominant lesions in these organs. The other lesions recorded in the liver were necrosis (15 cases), hepatitis (19 cases), fibrosis (9 cases) and cirrhosis (2 cases). One case each of cholangiocarcinoma, hepatic cyst and adhesion of diaphragm and the liver was encountered in the present study. Among kidney disorders, glomerular lesions were predominant next to vascular and degenerative changes. A total of 59 cases had some lesions in the glomeruli of which, 32 hadglomerulonephritis. PGN was the predominant type of glomerulonephritis. Males had a higher predilection for PGN and it was common in animals less than three years of age. MN and MPGN were common in animals more than three years of age. The high incidence of glomerular lesions and their possible causes were discussed. Tubulo-interstitial nephritis was observed in 16 cases. Interstitial nephritis was common in males while both cases of pyelonephritis were seen in females. Acute interstitial nephritis was seen in animals less than five years of age while all cases of chronic interstitial nephritis was seen in animals more than five years of age. Bacterial isolations were obtained in the liver or kidney or both in only 14 cases. Viral etiology was suspected in two cases where intranuclear inclusions were seen in the hepatocytes and the glomerular epithelium. The high incidence of vascular lesions without any evidence for infectious etiology in rest of the animals suggested the involvement of some toxic factors. The importance of identifying the specific etiology in these suspected cases of toxic conditions and the need and scope for further studies in these lines were highlighted.
