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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, T
An 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.
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 V
The 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.
Open Access
Immunopathological response of the duck (Anas platyrrhyncos domesticus) to sublethal dose of selected agro-chemicals
(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1998) Vijayan, N; KAU; Valsala, K V
The study was conducted with the objective of assessing the teratologic, embryotoxic and immunopathologic effects of two agro-chemicals carbofuran and 2,4-D used in agricultural operations, on duck embryos and ducklings. The embryological studies included the observation on the embryonic defects and weight of the lymphoid organs along with the histopathologic and ultrastructural studies of the lymphoid organs like the bursa, spleen and thymus. The results showed that the contamination of the eggs with the above chemicals caused moderate deleterious effects on the lymphoid system, though no teratologic effects could be observed. The histological and ultrastructural changes also confirmed the deleterious effects at the tissue and cellular level. The immune system of the ducks exposed to the above chemicals for two different durations were assessed using a battery of tests. The humoral immune system was assessed based on the body weight, lymphoid organ weight, haematological evaluation, serum biochemical evaluation and the evaluation of HI titre against NDV. The cell-mediated immune system was assessed by the skin reactivity tests to DNCB and PHA. LMIT and GVHR were also employed to assess the cell-mediated immune system. The histological and ultrastructural studies were also conducted after six weeks and ten weeks of the experiment. The assessment of the immunological profile employing these elegant tests revealed that these agro-chemicals caused mild but significant suppression of the cell-mediated and humoral immune response. By this investigation it was clarified that these agro-chemicals have mild to moderate degree of immunotoxic effect when exposed for a short duration, but the changes were severe when exposed for longer duration. From the .studies, it was demonstrated that the immunotoxic effect of carbofuran is more compared to 2,4-D (herbicide) and the changes were dose and time dependent.
Open Access
Prevalence and pathology of dermatological disorders in cattle
(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1996) Anilkumar, R; KAU; Rajan, A
A study was undertaken to assess the prevalence and pathology of dermatological disorders encountered m cattle m Kerala To study the prevalence of various types of skin disorders data were collected from the Disease Surveillence Report published by the Directorate of Animal Husbandry during the period 1989 1993 The various skin disorders encountered according to this data were tail necrosis (1 44 per cent) cutaneous mycosis (10 58 per cent) Eczematosis (6 09 per cent) pox (4 75 per cent) tick infestation (37 22 per cent) lice infestation (25 72 per cent) mangy dermatitis (13 82 per cent) wart (0 36 per cent) In this study tick infestation was found to be highly prevalent. Dunng the course of this investigation skin biopsies collected from 97 cattle were subjected to detailed gross and histopathological examination They were classified as Cutaneous ulceration (22 68 per cent) Fly bite dermatitis (15 46 per cent) Decubitus ulcers (12 47 per cent) Hyperkeratosis (9 3 percent) Papillomatosis (9 27 per cent) Hypertrichosis (8 25 per cent) Ectoparasitic mjuiy (6 19 per cent) Teat lesions (6 19 per cent) Fibroma (2 07 per cent) Dermatophilosis (1 03 per cent) Squamous cell carcinoma (1 03 per cent) and Fibrosarcoma (1 03 per cent) Cutaneous ulceration was the most common disorder encountered and Biopsies revealed epidermal lysis In fifteen animals fly bite dermatitis was noticed with greyish white necrotic papules and wheals on the neck shoulder ears and around eyes Perivascular changes were seen microscopically Nine cases of hyperkeratosis were studied which may be associated with hypovitammosis A Udder and teat papillomatosis was encountered m nine animals with ballooning degeneration and clumping of keratohyahn granules microscopically Eight crossbred cattle recovered from the foot and mouth disease had hypertrichosis Hair coat was shaggy and wavy Ectoparasztic injury was encountered m cattle mainly due Boophilus infestation Teat lesions encountered were mamly due to traumatic injury and chapping Two cases of fibroma and one case of fibrosarcoma were encountered on the teat of cattle A growth on the vulval region was diagnosed as squamous cell carcinoma An expenmental study on the cutaneous hypersensitivity reaction m cattle to PHA, 2 4 DNCB and BCG was earned out Mast cell response to these mitogens was also studied Effect of Agropesticides Furadan and BHC on local application on the skin of calves were studied Dermatosis was the charactenstic response The need for taking care to avoid pesticide contamination on the skin of animals was stressed
Open Access
Aflatoxin induced cytological alterations in ducks
(Department of Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1996) Vigil Anbiah, S; KAU; Manomohan, C B
An experimental study was conducted in desi ducks to assess the cytological alterations induced by aflatoxin Bl (AFB1) and 4 dimethyl amino azo benzene (4 DAB) One hundred and eight desi ducks of one month age were selected for the study The birds were divided into two treatment groups which were given A1 Bl (l0ug/kg body weight and l5ug/ kg body weight) and 4 DAB (5 mg and 10 mg/kg body weight) and a control group each group consisted of thirty six birds Body weight haemogram clotting time total serum protein serum albumin serum globulin albumin-globulin ratio serum aspartate amino transferase serum alanine amino transferase serum bilirubin and cytogenetic assay were estimated at periodic intervals The ducks were subjected to detailed autopsy and histopathology Clinically the exprimental birds were healthy Anaemia leucocytosis and increased blood clotting time were noticed in birds which received 15 ug/kg body weight o f AFB1 and both the dose levels of 4 DAB Total serum protein was reduced in all the treated birds In the aflatoxin group serum albumin and globulin levels were decreased Albumin globulin ratio was increased in 4 DAB tieated buds Serum aspartate ammo transferase level was elevated in buds winch moved 10ug/kg body weight of A1 Bl and 10 mg/kg body weight of 4 DAB Birds which received ATB1 as well as 10 ing/kg body weight of 4 DAB showed an elevation in serum alanine amino transferase level Serum bilirubin was incieased in all the treated birds Those ducks which were fed with AFB1 at 1 5ug/kg body weight showed tendency of hepatoma formation during the experiment The ducks which received 5 mg/kg body weight of 4 DAB exhibited gross and histopathological lesions suggestive of hepatosis and mild curhosis 1 he birds given 10 mg/kg body weight of 4 DAB tevealed gross as well as histopathological lesions of hepatic degeneiutiou and necrosis and indications of neoplatic changes Trend towaids polyploidy was the major chromosomal aberration observed in ducks which received 15g/kg body weight of AFB
Open Access
Neuropathology and diagnosis of rabies in domestic animals
(Department of Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1996) Silamban, S; KAU; Ramachandran, K M (Guide)
An investigation was made to study the epidemiology, clinical signs, pathologic lesions and diagnosis of rabies in domestic animals in the state of Kerala. Epidemiology of rabies for the last 12 year period from July 1983 to June 1995 was assessed from the post – mortem records maintained at the department of Pathology. Regional distribution, Prevalence in each species and year – wise occurrence were studied. Canine rabies was found preponderant. Rabies was recorded in wild animals also. Detailed clinical signs and gross pathological changes in the rabies positive cases were studied. One hundred and six rabies suspected carcasses of different species of animals were examined for the disease employing Sellers’ impression smear staining, histopathology, fluorescent antibody test (FA test) and immunoperoxidase test (IP test). Twenty – two of them were confirmed positive for rabies. Negribodies were demonstrated with Sellers’ staining and histopathological staining. Sellers’ staining was identified to be the simple and rapid staining method that could be employed in the field laboratories. In addition to H & E, Mann’s stain and Sellers’ stain were applied for staining histological sections. H & E was found to be satisfactory for routine staining. Histological changes in the brain (cerebrum, cerebellum and hippocampus), salivary gland (parotid and submaxillary) and trigeminal nerve of rabies positive animals were studied. The efficacy of the diagnostic techniques used for rabies diagnosis was compared. FA test confirmed maximum number of rabies positive cases. The results of the rabies diagnosis was cross – checked by Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Oregon State University, USA.
Open Access
Pathology of bacterial mastitis in bovines
(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1998) Nandakumar, S; KAU; Sreekumaran, T
The pathology of bacterial mastitis in bovines was studied considering the following aspects such as bacterial isolation; changes in milk, antibiotic sensitivity pattern, haematology, whey protein pattern and histopathological examination of the mammary gland and supramammary Iymphnodes. Two hundred and sixty two samples were found to be subclinically positive based on California Mastitis Test. The organisms isolated from clinical and subclinical cases were Staphylococcus, E. Coli, Gram negative bacilli, mixed infections, Streptococcus, Yeast and Gram positive bacilli in the decreasing order of prevalence. All the major pathogens were sensitive to pefloxacin, gentamycin and chloramphenicol and resistant to penicillin. Leucopenia could be noticed in clinical and subclinical cases of mastitis. Relative neutrophilia could be observed in mastitic animals. Total plasma protein was also increased. There was an increase in T-Iymphocyte count in mastitis affected animals. ~omatic cell count was increased in clinical and subclinical cases, but was not indicative of infection, unless confirmed by bacteriological examination. SOS-PAGE on whey proteins revealed an increase in protein content in mastitic milk as a result of the plasma proteins, cellular proteins, bacterial proteins. There was marked increase in immunoglobulins in mastitic milk, when compared to normal. Histopathology of mammary glands revealed the presence of inflammatory cells in the acini and interstitium of mammary glands as the main lesion. Varying degrees of inflammatory reaction could be noticed in almost all the quarters. Supra mammary lymph nodes revealed distension of subcapsular sinuses, active secondary follicles in the cortex, sinus catarrh and medullary hyperplasia in mastitis affected animals.
Open Access
Comparative pathology of aflatoxicosis in the duck and fish with special reference to the immune system
(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1998) George, K C; KAU; Rajan, A
Pathological responses of ducklings and juvenile Indian carps Labeo rohita in experimental aflatoxicosis were studied. Both the ducklings and fishes were given sublethal toxic levels of aflatoxin B1. The ducklings and fishes were exposed to aflatoxin B1 for 2, 4, 6 and 8 weeks respectively and they were sacrificed at the end of the experiment and samples for haematological, serum protein profile, histological and ultrastructural investigations were collected. Pathological changes were studied with special reference to the humoral and cell – mediated immune responses. Among the haematological parameters, total erythrocyte count, total leucocyte count and packed cell volume were found to be reduced in fishes. The reduction was directly proportional to the duration of aflatoxin treatment. In the fishes, there was moderate fall in the total proteins and the albumin. The electrophoretic picture of the serum of the fishes also showed fall in the albumin fractions. In the ducks there was severe reduction in the albumin level and this was reflected in the electrophoretic picture as well as A: G ratio. In both the ducks and the fishes humoral immune response was suppressed due to aflatoxin treatment. Antibody titres against sheep RBC fell in the experimental groups of the ducks and the fishes. The cell - mediated immunity was assessed in the ducks and the fishes by intradermal PHA – M response, count of ANAE positive lymphocytes in the peripheral blood and leucocyte migration inhibition test. In the ducks and the fishes of the aflatoxin treated groups, there was significant fall in the skin sensitivity response and also in the number of ANAE positive lymphocyte. These findings clearly established that CMI was suppressed by aflatoxin . The histological and electron microscopic studies revealed severe degenerative and necrotic changes in the hepatocytes in the ducks and fishes. However, hepatosis was more severe in the fishes whereas in the ducks biliary proliferation was a prominent feature. The hepatic changes could be correlated with the changes in the plasma protein profile in the duck and the fish. The lymphoid organs of the duck and the fish (thymus, spleen, bursa of Fabricius and anterior kidney) showed extensive necrosis and degenerative changes. These changes clearly established the reason for the immunosuppression and low leucocytic counts observed in the aflatoxin fed ducks and fishes. The kidneys of the duck and the fish exhibited nephrotic changes. Degenerative changes were also observed in the brain and the heart of the two species. The pathologic changes due to aflatoxicosis were comparable in the ducks and fishes.
Open Access
Comparative study of the immunopathological response in ochrathoxin A, cadmium and mercury toxicities in ducks (Anas platyrrhynchos domesticus)
(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 1996) Vyas Madhavrao Shingatgeri; KAU; Rajan, A
The present investigation was undertaken for the first time to assess the level of contamination of mercury (Hg) and Cadmium (Cd) in the soil, water, plants and biosamples in localities where there is significant duck population and to study the pathological effects of these chemicals and ochratoxin A (OA) with special reference to immune response in the ducks and duck embroys. The residues of these chemicals in various tissues of the ducks were also assessed. Hg and Cd were detected in all the samples from all the localities surveyed and its presence especially in the soil, vegetation, fish, liver and kidney of the ducks from these areas indicated its public health significance. After the administration of OA, HgCl2 and CdCl2, there was dose dependent embryo mortality and reduction in hatchability rate. The mortality percentage in the highest dose group of embryos inoculated with HgCl2, Cdcl2 and OA was 55%, 51.6% and 48.3% respectively while the hatchbility rate was 29.92%, 35% and 47.83% respectively. This clearly indicated the embryotoxic action of these chemicals. The body weight, weight of the thymus, and the bursa of Fabricius was found lowered in the embryos inoculated with these chemicals. The variations noticed in the weights at different periods of observation between the chemicals were also dose dependant. The weight of the spleen of the embryos inoculated with OA and HgCl2 was comparable to the normal embryo but with CdCl2, it was found significantly lowered in the highest dose group at the 28th day of incubation. These observations, therefore indicated that Cd has an adverse significant biological effect on the lymphoid organs of the developing embryo. Similar effect was observed with Hg and OA but was relatively low. Histologically, depletion of the lymphoid elements consequent to degeneration, necrosis and cytolysis was the characteristic feature in the bursa of Fabricius and thymus, however, it was comparatively less in the spleen. Ultrastructural changes in the lymphoid cells in all these organs showed membrane alterations, mild to severe mitochondrial changes, ribosomal detachment and fragmentation of RER and nucleolar and nuclear changes indicative of cell damage, and marked reduction in differentiation into plasma cells. Epithelial cells were also found affected. The toxic effects of these chemicals were more or less similar in the bursa of fabricius, intensity and severity being more with CdCl2 followed by HgCl2 and OA in that order. In the thymus, also, CdCl2 caused severe pathological effects while with HgCl2 intensity was least. In the spleen there was increased erythrophagocytosis in addition to these changes and was more severe with HgCl2. In the liver, severe necrobiotic changes were found in the hepatic cells associated with ultrastructural picture of organellar damage and lytic changes in the nucleus. Intensity of these changes was more severe in CdCl2 treated embryos followed by those treated with OA and with HgCl2. In the kidney, the cellular alterations were more in the proximal convoluted tubules and the intensity of these alterations was less in OA and CdCl2 treated embryos compared to those treated with HgCl2. The embryos inoculated with OA, HgCl2 and CdCl2, revealed degenerative changes in the lymphoid and other organs. The adverse immunobiological effects of OA, Hg and Cd on the developing embryo were established by histological and ultrastructural studies. In the ducks, OA, HgCl2 and CdCl2 were fed orally (at the rate of 300 ug, 10mg and 15 mg/kg body weight respectively) for 90 days. Clinically ducks showed dullness, restlessness and unusual hyperresponsiveness and inco – ordination of movement, in OA, HgCl2 and CdCl2 fed ducks respectively at the later stage of the experiment. Progressive reduction in the gain of the body weight, of the bursa of Fabricius was noticed in all the groups (OA, HgCl2 and CdCl2 treated) while that of the thymus was noticed mainly in CdCl2 and OA treated ducks. There was highly significant reduction in the total erythrocyte count (TEC), Haemoglobin (Hb) concentration and Packed Cell Volume (PCV) in the groups fed OA, HgCl2 and CdCl2. Highly significant leucopaenia with relative heterophilia and lymphocytopenia was observed in OA and HgCl2 fed ducks, while highly significant leucocytosis with heterophilia and lymphocytopenia was seen with CdCl2 fed ducks. These alterations revealed the toxic action of these chemicals on the haemopoietic cells and the formed elements of the blood. Estimation of the haemagglutination inhibition (HI) antibody titre, total serum protein (TSP), serum globulin (SG) and serum IgG and IgM levels clarified the adverse effect of OA, Hg and Cd on the humoral immune system, which was evident at an early stage in Cd and Hg treated ducks while at a later stage in OA fed ducks. There was marked reduction in the serum IgM and IgG level in response to New Castle disease Virus (NDV) in ducks fed HgCl2 and CdCl2 respectively. The highly significant reduction in the T – lymphocyte count in the peripheral blood, increase in the migration indices in response to NDV in leucocyte migration inhibition test (LMIT), reduction in cutaneous response to phytohaemagglutinin – M (PHA – M), 2, 4 – dinitrochlorobenzene (DNCB) and the decreased spleen indices in Graft versus host reaction (GVHR) indicated the toxicity of OA and Cd on the cell – mediated immunity, which was more pronounced and evident at an early stage in Cd treated ducks than compared to OA treated ducks. However, the results of the migration indices, PHA – M cutaneous response and GVHR demonstrated that the CMI response escape the toxic insult of the Hg and is dependant on the duration of exposure, which was clarified by T – cell dependant lymphocytopaenia and reduction in cutaneous response to DNCB at the last week of the experiment. Significant reduction in the phagocytic ability in all the ducks treated either with OA, HgCl2 or CdCl2 was observed by carbon clearance assay. There was reduction in the weight of the bursa of Fabricius and spleen. The thymus showed focal areas of congestion and petechiae in Cd induced toxicity, and was found appreciably reduced and atrophied with Cd and at later stages with OA. Degenerative and retrograde changes indicative of necrobiosis were observed histologically. Ultrastructural changes were more severe with CdCl2 followed by HgCl2 and OA in that order. In the spleen of ducks fed CdCl2 there were proliferative changes initially followed by degenerative changes at later stages. In the thymus, effect of the Cd was more severe on the lymphocytes followed by OA and was least with HgCl2. Histological and ultrastructural studies revealed degenerative nephropathic changes in the kidney associated with Hg, OA and Cd toxicity. Intensity of alterations was more with Cd. The hepatic lesions characterised by moderate to severe hepatosis were more pronounced in the case of Hg and Cd in an increasing order. Histological and electron microscopic studies elucidated the neuropathological changes associated with Hg, Cd and OA toxicity. Estimation of OA, Hg and Cd residues indicated a steady increase in the accumulation of these substances in the various tissues depending on the dose and duration of exposure. Highest concentration of OA, Hg and Cd was detected in the kidney, followed by liver. Residues of these substances at varying concentrations were also detected in the muscles, brain, spleen, bursa of Fabricius and thymus. This study brought to light the immunosuppressive effect of OA, Hg and Cd which would compromise the dichotomous defence mechanism of the ducks. Also adverse effects on hepatic, haemopoietic, reneal and nervous system were documented. It was clarified by this investigation that immunotoxic effect of these chemicals could lead to breakdown of immunity and outbreak of diseases when the ducks are maintained in a polluted environment. The need for the systematic monitoring of the environment and taking appropriate steps to prevent environmental pollution were stressed. The public health importance of residues of these chemicals was brought to light.

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