Effect of neonatal thymectomy and antilymphocyte globulin on non-specific mitogen stimulation in Holstein-Friesian calves

Nine of seventeen neonatal Holstein-Friesian calves were thymectomized, treated with antilymphocyte globulin, and monitored for immunologic functional ability for 4 to 6 months. The thymus weights for 4 to 10-day-old calves and 4 to 6-month-old calves indicated a continued increase in total weight. This indicated significant thymic involution had not occurred at 4 to 6 months. Following thymectomy a wasting syndrome was not observed although an increased incidence of a lowly virulent virus infection did occur. A significant decrease in circulating lymphocytes was observed.Peripheral blood lymphocytes were stimulated in vitro by non-specific mitogens, phytohemagglutinin, bacterial lipopolysaccharide and pokeweed mitogen using the whole blood culture method. Observations included a greater response to phytohemagglutinin and pokeweed mitogen in summer months and variable age related response to all mitogens. Lipopolysaccharide stimulation results were inconclusive. It was concluded that neonatal thymectomy was not a satisfactory experimental procedure for the production of selective immunosuppression in the bovine species.     

Experimental primary postnatal bovine viral diarrhea viral infections in six-month-old calves

Eight clinically healthy calves were inoculated intranasally, four with either noncytopathic or four with cytopathic bovine viral diarrhea virus, and were necropsied 5 or 12 days post-inoculation. The most frequent gross lesion associated with noncytopathic or cytopathic viral infection was proximal colonic mural edema. Consistent microscopic findings were acute to subacute tracheitis, mild enterocolitis with edema, petechial hemorrhages of mesenteric lymph nodes with mild follicular lymphocytic depletion, and paracortical lymphocytic hyperplasia. At necropsy, cytopathic virus was recovered from 4/4 calves and noncytopathic virus was isolated from 2/4 calves. Neutralizing antibodies to noncytopathic bovine viral diarrhea virus were detected in the two calves from which noncytopathic virus was not recovered. Immunohistochemical analysis of lymphoid tissues demonstrated a small, randomly distributed population of mononuclear cells that contained bovine viral diarrhea viral antigen in 7/8 calves.     

An outbreak of sarcocystosis in dairy cattle

Sixteen of 32 Friesian calves, 8 to 10 weeks old, died over 4 weeks. The calves were housed in pens previously used by dogs. Clinical signs included anorexia, pale mucous membranes, rapid weight loss, coughing and palpably enlarged superficial lymph nodes. At necropsy, calves were emaciated and had generalised enlargement of lymph nodes, pale mottling of skeletal muscles, excess peritoneal, thoracic and pericardial fluid and subpleural and subepicardial haemorrhages. Histologically there was a lymphadenitis, myositis, myocarditis, glomerulonephritis, interstitial pneumonitis and encephalitis. Schizonts of a sporozoan parasite, presumably Sarcocystis cruzi were found in the endothelial cells of blood vessels in many organs.     

Genital neoplasms treated by en bloc resection and penile retroversion in horses: 10 cases (1977-1986)

The medical records of 10 horses with invasive neoplasms of the penis, prepuce, and/or superficial inguinal lymph nodes in which treatment involved en bloc resection and penile retroversion were reviewed. All were geldings and ranged in age from 12 to 25 years (mean, 19 years). Evaluation of biopsy specimens obtained before surgery confirmed lymphosarcoma in 1 horse and squamous cell carcinoma in 9 horses. Typical history included swelling, ulceration, and abscessation of the penis and prepuce and large superficial inguinal lymph nodes. Complications after surgery included dehiscence of the urethrostomy site (4 horses), dehiscence of the ventral skin incision (1 horse), urine scalding of 1 hind limb (1 horse), cystitis (1 horse), severe hemorrhage (1 horse), and diarrhea (1 horse). One horse was euthanatized during hospitalization, because of severe dehydration secondary to diarrhea. At necropsy, firm nodules were scattered in the pulmonary parenchyma, myocardium, thyroid gland, parathyroid glands, cranial mediastinum, kidneys, and hilar lymph nodes. Microscopic examination of the nodules revealed undifferentiated carcinoma. Nine horses were discharged from the hospital between 1 and 5 weeks after surgery. The mean follow-up interval was 27 months (range, 6 to 96 months). Eight horses had no evidence of recurrence. One horse had recurrence of neoplasm at 6 months and was euthanatized 12 months later.     

Pancytopenia Secondary to Lymphoid Leukemia in Three Horses

Pancytopenia was observed in two 3-year-old geldings and one 11-year-old mare. All horses had a brief history (2 days to 4 weeks) of fever, anorexia, and depression. One of the three horses had blast cells present on a peripheral blood smear. Examination of the bone marrow showed substantial infiltration with neoplastic lymphoid cells. At necropsy, neoplastic cells were restricted to the bone marrow in one horse, present in bone marrow, liver, and spleen in the second horse, and reported in multiple tissues in the third horse, including bone marrow, kidneys, lung, myocardium and lymph nodes. The value of a bone marrow aspirate and core biopsy in the investigation of pancytopenia is highlighted. (Journal of Veterinary Internal Medicine 1993; 7:360–363. Copyright © 1993 by the American College of Veterinary Internal Medicine.)     

Bacterial survival, lymph node changes, and immunologic responses of cattle vaccinated with standard and mutant strains of Brucella abortus.

Forty-eight cattle were used in 4 experiments; 6-week-old calves in experiments 1-3 (n = 24) and 10-month-old heifers in experiment 4 (n = 24). In experiments 1-3, 7 groups of 3 calves each were inoculated SC with 5 strains of Brucella abortus: virulent strain 2308 (2 groups), vaccine strain 19 (2 groups), and mutant strains RB51. 19 delta 31K, and 19 delta SOD. Sera and lymph node tissues were examined at 2-week intervals for evidence of infection. At postinoculation (PI) week 12, 2 calves in each group were given dexamethasone for 5 days. Calves were then euthanatized and lymphoid tissue, spleen, liver, and bone marrow were examined for evidence of B abortus. Calves given strain 2308 had large numbers of bacteria in their lymph nodes, marked granulomatous lymphadenitis in the deep cortex, and loss of lymphoid cells in superficial cortical areas. In addition, they had high serum antibody titers at PI week 16. Calves given strain 19, or genetic mutants derived from strain 19, cleared bacteria from lymph nodes more rapidly, had less lymphoid destruction, and developed antibody titers that did not persist for 16 weeks. The RB51 strain (rough) was cleared most rapidly from lymphoid tissues and induced serum antibody responses only to the core of the lipopolysaccharide molecule. Treatment of calves with dexamethasone did not cause B abortus to reappear in tissues of any calves, nor did serum antibody titers increase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical and pathological findings in feline immunodeficiency virus experimental infection.

A study is described of the clinical and pathological findings in 20 specific pathogen free cats infected when 1 year old with feline immunodeficiency virus and monitored over 12 months. Cats were divided into two groups (A and B). The clinical and clinicopathological features were studied in Group A. In Group B, at 1, 2, 4, 9 and 12 months post infection two cats were necropsied. Clinically all cats developed generalised lymphadenopathy, six cats were neutropenic and five cats lymphopenic. Three cats became febrile with conjunctivitis and anterior uveitis and one of these cats ultimately developed jaundice. Postmortem examinations confirmed a generalised lymphadenopathy involving peripheral and visceral lymph nodes with concurrent stimulation of splenic white matter and mucosal lymphoid tissue of the digestive tract and conjunctiva. Within the lymph nodes there was a reactive follicular hyperplasia accompanied by a paracortical hyperplasia with an increased paracortical vascularity. Unusual features were the presence of lymphoid follicles in the bone marrow, thymus and parathyroid tissue. In addition, aggregates of lymphoid cells were found within salivary glands, kidneys, sclera and choroid of the eye. One cat developed a lymphosarcoma affecting the liver and kidneys at 36 weeks post infection. The cat with jaundice had a cholangitis with marked biliary epithelial hyperplasia.     

Tumor-associated antigen on bovine leukemia virus-induced bovine lymphosarcoma

Specific tumor-associated antigen (TAA) was detected on enzootic bovine leukosis (EBL) cells by monoclonal antibodies against TAA. One of the monoclonal antibodies, c143, reacted with all EBL tumor cells tested but not with bovine leukemia virus (BLV) antigens. c143 reacted slightly with bovine fetal thymus and mitogen-stimulated lymphocytes from BLV-free cows but not with normal bovine lymphoid cells. TAA may be a good tumor marker of EBL tumor cells. We sacrificed eight TAA-positive but clinically normal animals and examined them in order to elucidate whether or not they had gross or histological tumors. At necropsy, four animals had tumors macroscopically. Three animals had no tumors histologically but had initial lesions showing follicular hyperplasia and the TAA on affected lymph nodes. The one remaining showed medullary hyperplasia in the spleen but there were no findings of tumors. Thus, c143 is a useful tool not only for diagnosing EBL, but also for screening of BLV-infected cattle with potential to develop tumors in the future.     

Influence of thymectomy on the susceptibility of cats to feline leukemia virus and lymphosarcoma.

Twelve cats were thymectomized at 5 weeks of age. Six of these cats were inoculated at 8 weeks of age and 6 at 4 months of age with the Rickard (R) strain of feline leukemia virus (FeLV), which produces a high incidence of thymic lymphosarcoma. Two groups of age-matched nonthymectomized cats were inoculated with the same FeLV-R stock. Thymectomy prior to FeLV infection had no influence on the induction of viremia or the incidence of lymphosarcoma. In the FeLV-inoculated nonthymectomized cats, lymphosarcoma developed in the thymus. In the thymectomized cats, lymphosarcoma developed in the intestine, mesenteric lymph nodes, and bone marrow, but the malignant lymphoblasts had surface markers characteristic of feline T lymphocytes. It was concluded that the presence of the thymus per se is not required for infection and oncogenesis by FeLV and that feline T lymphocytes may be transformed after peripheralization to other tissues.     

Extreme eosinophilia with disseminated eosinophilic granulomatous disease in a horse

Extreme eosinophilia with disseminated eosinophilic granulomatous disease is described in a 4-year-old Arabian mare. Clinical signs included weight loss, coughing, jugular distention, and ventral edema. Cutaneous lesions were not observed. Eosinophilic inflammation was observed in cytologic specimens from the respiratory tract, body cavities, and lymph nodes. At necropsy, a 20-cm diameter intrathoracic mass was observed. Smaller nodules were present in the lymph nodes, liver, spleen, adrenal glands, pancreas, and skeletal muscle. Histologically, these masses and nodules were characterized by infiltrates of eosinophils, macrophages, and multinucleated giant cells, reactive fibroplasia; and multifocal eosinophilic coagula. Microscopically, mild eosinophilic infiltrates were observed in sections of stomach, small intestine, colon, and pleura; however, gross lesions were not observed in these tissues at necropsy. The etiology of the extreme eosinophilia and disseminated eosinophilic granulomatous disease in this horse was not determined.     

Bovine arsenic toxicosis.

A ranch in central South Dakota had a number of dead calves because of arsenic poisoning. The clinical picture included diarrhea, central nervous system signs, and death. Gross necropsy findings included adequate body fat, stomachs full of normal-appearing ingesta, and large amounts of greenish brown watery fluid in the intestine and colon. Microscopically there was severe lymphoid tissue necrosis in the mesenteric lymph nodes and gut-associated lymphoid tissue. Chemical analysis of kidneys showed no significant amounts of lead; however, kidney arsenic concentrations were 25 to 44 ppm. The source was a small pile of Paris Green (common name for cupric acetoarsenite) found in an old dump site in the pasture.     

Distribution of viral antigen and tissue lesions in persistent and acute infection with the homologous strain of noncytopathic bovine viral diarrhea virus.

Viral distribution and lesions were compared between calves born with persistent infection (PI) and calves acutely infected with the same bovine viral diarrhea virus (BVDV) isolate. Two PI calves from 1 dairy herd were necropsied. The PI viruses from these calves were isolated, characterized by sequencing, and found to be identical. This virus strain, designated BVDV2-RS886, was characterized as a noncytopathic (ncp) type 2 BVDV. To establish acute infections, BVDV2-RS886 was used to inoculate clinically healthy, seronegative calves which were 3 weeks to 3 months old. Nine calves received 10(6)-10(7) tissue culture infective dose of BVDV2-RS886 intranasally. Four additional age-matched animals served as noninfected controls. Infected calves were necropsied at 3, 6, 9, or 13 days postinoculation (dpi). Viral antigen was detected by immunohistochemistry in frozen sections, and lesions were evaluated in hematoxylin eosin-stained paraplast sections. In the PI calves, a wide distribution of viral antigen was found in all tissues and was not associated with lesions. In the acutely infected calves, viral antigen was widespread in lymphoid tissues at 6 dpi but had been mostly eliminated at 9 and 13 dpi. Depletion of lymphoid tissues was seen at 6, 9, and 13 dpi and repopulation at 9 and 13 dpi. In 1 of the calves at 13 dpi, severe arteritis was present in lymph nodes and myocardium. This comparison shows that an ncp BVDV strain that causes no lesions in PI animals is able to induce marked depletion of lymphoid tissues in calves with acute infection. Therefore, the failure to eliminate PI cattle from a herd causes problems not only in pregnant cattle but may also affect other age groups.     

Distribution of Brucella abortus organisms in calves after conjunctival exposure

Thirty calves (3 to 4 months old) were exposed conjunctivally to a pathogenic strain of Brucella abortus. Calves were euthanatized and necropsied at postexposure hours 2 and 4, and at postexposure days (PED) 1, 4, 7, 14, 21, 42, and 49. Selected ocular, pharyngeal, and lymphoid tissues were cultured bacteriologically for brucellae to determine organism distribution. Brucella abortus organisms initially localized in the third eyelids, bulbar conjunctivae, and parotid lymph nodes and were detected in these structures until PED 42, 21, and 49 respectively. In calves euthanatized at PED 7, organisms were in other cranial lymph nodes (mandibular and retropharyngeal), and in calves euthanatized at PED 21, organisms were isolated from peripheral lymphoid tissues. Brucellae were not isolated from mesenteric and bronchial lymph nodes and from the spleen until PED 21. The pattern of isolation indicated that conjunctival exposure probably resulted in entrance of brucellae into the host via ocular tissues.     

Experimentally induced bovine sarcocystosis: correlation of in vitro lymphocyte function with structural changes in lymphoid tissue

The effect of acute bovine sarcocystosis was studied by correlating in vitro lymphocyte blast transformation studies with morphologic and hematologic changes. Yearling calves inoculated with 900,000 sporocysts (large dose) had decreased responses to phytohemagglutinin and pokeweed mitogen and corresponding morphologic evidence of depletion of both T and B lymphocytes in all lymphoid organs examined during the first 4 weeks. The T-cell depletion was characterized by marked thymic atrophy. In lymph nodes denoting B-cell depletion, there were lymphoid follicular exhaustion and various degrees of follicular loss. Significant change in total circulating lymphocytes was not observed. All animals given this large dose died or were killed (in a moribund state) by 5 weeks after they were inoculated. Changes in mitogen responsiveness were not significant during the 4 weeks after yearling calves were inoculated with 90,000 sporocysts (small dose). The mitogenic effect of phytohemagglutinin was significantly greater than that of the control group during weeks 4 to 18. During this period, morphologic evidence of thymic cortical regeneration occurred. The results indicate that acute sarcocystosis is accompanied by a lymphoid abnormality which could result in immunosuppression, adding to the severity of natural infection.     

Theileria parva infection in calves causes massive lymphocyte death in the thymus, spleen and lymph nodes without initial proliferation

In a study of trends and magnitudes of lymphocytes proliferation, destruction or apoptosis eleven 3-month-old healthy calves were experimentally infected with the protozoan parasite Theileria parva, which is reported to cause lymphocyte proliferation. Four control calves were not infected. Infected and non-infected calves were sacrificed on days 9, 12, 16, 19, 23, 24 and 25 to examine lymphoid tissue changes and lymphocyte proliferation, apoptosis or necrosis in the thymus, spleen and lymph nodes. All infected calves developed severe East Coast fever, with enlargement of lymph nodes, dyspnoea, high fever and pulmonary oedema. Lymphocyte proliferation was not observed in lymph nodes, thymus and spleen; instead there were massive deaths of lymphocytes and other cells. The terminal severe disease caused massive lymphoid parenchyma coagulation terminating with caseation, organs and cells being undeterminable histologically. Tissues surrounding the lymph nodes were oedematous. Lymph node and thymus parenchyma were caseated and cortices and medulla indistinguishable because of severe lymphocyte and accessory cell deaths. The lymph node fibrous reticular stroma was necrotic and caseated. Lymphoid follicles in lymph nodes degenerated and lacked germinal centres. Lymph nodes, spleen and thymus were grossly enlarged, hardened, potato or cheese like, but microscopically very hypocellular and in the terminal disease acellular because of massive lymphocytes destruction. In the thymus there was extensive thymocyte and epithelioid cell necrosis and loss of distinction between cortex and medulla. The spleen white and red pulps were indistinguishable because of extensive lymphoid cell necrosis. The white pulp degenerated more than the red pulp. The massive lymphocyte deaths in the lymph nodes, thymus and spleen, without lymphocyte proliferation in this T. parva infection in calves leads to a conclusion that this parasite is lympho-destructive and lympho-degenerative in vivo rather than lympho-proliferative.     

Combined immunodeficiency in a calf

Combined immunodeficiency was documented in a 6-week-old Angus calf. The calf had lymphopenia, undetectable serum IgM or IgA, and low concentrations of serum IgG (420 mg/dl). The calf was treated for diarrhea, pneumonia, and shock, and was given antimicrobial drugs, fluids, and plasma. The calf died of systemic candidiasis and Escherichia coli bacteremia. Aggregated lymphatic folliculi (Peyer patches), lymph nodes, and thymic and splenic lymphoid tissue could not be identified at necropsy.     

Effects of the timing of the administration of Mycoplasma hyopneumoniae bacterin on the development of lesions associated with porcine circovirus type 2

To determine whether there is an effect of the timing of vaccination on porcine circovirus type 2 (PCV-2) replication and PCV-2-associated lesions, 78 pigs were randomly assigned to eight groups: group 1 (10 pigs) was vaccinated with a commercial Mycoplasma hyopneumoniae vaccine at two and four weeks of age, group 2 (nine pigs) was vaccinated at four and six weeks of age, group 3 (10 pigs) at six and eight weeks of age and group 4 (10 pigs) at eight and 10 weeks of age; group 5 (nine pigs) was vaccinated once with a double dose at four weeks of age, and group 6 (10 pigs) was vaccinated once with a double dose at eight weeks of age. Groups 7 and 8, both of 10 pigs, were not vaccinated. At eight weeks of age, the pigs in groups 1 to 7 were inoculated with PCV-2. Fourteen days after they had been inoculated, the pigs in groups 1, 4 and 5 had significantly (P<0.05) more copies of the PCV-2 genome in their serum than the unvaccinated pigs. Microscopically, 14 of the 68 inoculated pigs had normal lymphoid tissues, 40 had mild PCV-2-associated lymphoid lesions and 14 had moderate lesions. The mean overall lymphoid lesions (lymphoid depletion, granulomatous inflammation, and quantity of PCV-2 antigen in spleen, tonsil, and five lymph nodes) were significantly (P<0.05) more severe in groups 4 and 5 than in groups 2, 3, 7 and 8.     

Studies on immunisation of suckling calves with dictol

The immunisation of young milk-fed calves with two doses of the commercially available Dictyocaulus viviparus irradiated larval vaccine, Dictol, was studied. In the first experiment, vaccination of groups of pail-milk-fed calves at 3 and 7 weeks of age resulted in 96.7% reduction of lungworm burdens upon challenge when compared with non-vaccinated controls. Contemporaneous vaccination of calves aged 8 and 12 weeks resulted in a reduction in lungworm burden of 98.9% compared with controls of the same age. The clinical reaction upon challenge of both age groups was minimal compared with their respective controls.In the second experiment a group of six suckling calves were vaccinated with Dictol at 3 and 7 weeks of age and then challenged with infective larvae of D. viviparus together with non-vaccinated controls. At subsequent post-mortem examination the mean lungworm burdens of the vaccinates was 87% less than that of the controls. Some clinical reaction evidence by increased respiratory rates and bodyweight loss occurred in the vaccinates but this was not as severe as in the controls. At necropsy a concurrent pneumonia due to Mycoplasma spp. was present and it is suggested that this contributed to the poorer protection obtained compared with the pail-milk-fed calves of the fist experiment.In the third experiment a group of suckling calves were again vaccinated at 3 and 7 weeks of age and then exposed to a natural challenge together with parasite-naive controls. Although the level of challenge was relatively low, immunisation was apparently high successful as lungworms were completely absent in the vaccinates when examined at necropsy.In all three experiments numerous pulmonary lymphoid nodules, which are a useful guide to the immune status of calves, were present in the vaccinates and absent or scarce in the controls. It is concluded that the cumulative evidence from the three experiments suggest that immunisation against infections of D. viviparus of young milk-fed calves in the field may be a practical proposition.     

Anthelmintic efficacy of albendazole against adult Dictyocaulus viviparus in experimentally infected calves.

Anthelmintic activity of albendazole against adult Dictyocaulus viviparus was evaluated in a controlled experiment. Calves were raised nematode-free to approximately 8 weeks of age and were each given 4,000 infective 3rd-stage larvae. Twenty calves with patent parasitisms were allotted to 2 groups of 10 calves each. Calves in group 1 were used as nonmedicated controls, and calves in group 2 were given albendazole in paste formulation at the dosage concentration of 7.5 mg/kg of body weight on the 30th day after administration of infective larvae. At necropsy, nonmedicated control calves had a total of 308 adult D viviparus, whereas the albendazole-treated calves had 11, for an average efficacy of 96.4%. These reductions were statistically highly significant (P less than 0.01). At necropsy, none of the treated calves was passing 1st-stage C viviparus larvae in their feces, whereas control calves were passing an average of 46 larvae/10 g of feces.