Application of admissions criteria to applicants with practice versus non-practice career goals in North American schools /colleges of veterinary medicine

PURPOSE

The study was intended to determine whether North American veterinary schools/colleges apply admissions criteria differently to applicants with practice versus non-practice career goals.

METHODOLOGY

A written questionnaire with seven queries on admissions criteria was sent to the associate deans for academic affairs at each of the 31 North American veterinary schools/colleges.

RESULTS

Questionnaires were completed and returned by 25 of the 31 institutions. The responses were summarized and individual comments were compiled. For veterinary and animal experience, similar amounts but different types of experiences were acceptable to most institutions for applicants with practice versus non-practice career goals. The required pre-veterinary course work was not different for the two groups of applicants. The backgrounds of mentors providing written evaluations were often allowed to be different for the two groups of applicants. The responses expected in applicant interviews were different for the two groups for queries related to veterinary and career experiences and knowledge of specific career areas but were similar for various basic qualities and skills expected of all applicants.

CONCLUSION

Although institutions vary, North American veterinary schools/colleges tend to apply admissions criteria differently to applicants with practice versus non-practice goals, except for pre-veterinary course requirements.

Etiologic factors and pathologic alterations in selenium-vitamin E deficiency and excess in animals and humans

The etiology of selenium-vitamin E (Se-E) deficiency diseases may be complex. Many of the syndromes involve combined deficiency of selenium and vitamin E. Selenium moves into the animal and human food chain from soil and plants, which may contain inadequate amounts of the nutrient in many areas of the world. Vitamin E may be in low concentration in many animal feeds unless supplements are added. Some syndromes, such as steatitis in cats, result from an increased requirement of vitamin E in diets that contain large amounts of polyunsaturated fatty acids, and these diseases will only respond to vitamin E administration. Deficiency syndromes in animals owing to pure Se deficiency are infrequent and have been produced mainly by laboratory studies utilizing extreme deficiency conditions. Other factors that may affect the occurrence of these deficiency diseases are concurrent dietary deficiency of S-containing amino acids, bioavailability of different forms of dietary Se, intake of compounds that antagonize Se (e.g., silver salts), and exposure to various prooxidant substances (e.g., iron compounds, oxygen, ozone, and various drugs).

Serum chemistry alterations, including creatine kinase isoenzymes, in furazolidone toxicosis of ducklings: preliminary findings

Furazolidone induces a cardiotoxicosis when fed in toxic concentrations to newly hatched ducklings. This preliminary experiment was designed to determine if creatine kinase (CK) isoenzymic activities or other serum analytes would be useful as indicators of these cardiac alterations. Sera from 12 ducklings (six fed a control ration and six fed the control ration with 700 mg furazolidone added per kg of feed [700 ppm] for 28 days) were analyzed for CK isoenzymic activities, electrolytes, nitrogenous metabolites, hepatic enzymic activities, bilirubin, and glucose. Statistically significant differences between control and treated groups were detected for creatine kinase MB (CK-MB, cardiac muscle origin) isoenzymic activity and bilirubin, potassium, calcium, and total carbon dioxide concentrations. Differences other than CK-MB isoenzymic activity were generally explained by factors related to the toxicosis or sample handling. These findings suggest that CK-MB isoenzymic activity may be useful to detect and monitor the progress of cardiac injury in furazolidone toxicosis, thereby increasing the usefulness of this model of dilated cardiomyopathy. Our findings, analyzed on the Kodak Ektachem 700 Dry Chemistry Analyzer, are compared with serum chemistry values reported in the literature.

Early clinical and morphologic alterations in the pathogenesis of furazolidone-induced toxicosis in ducklings

Clinical and pathologic alterations during the development of furazolidone-induced toxicosis were investigated in a group of 35 newly hatched male Pekin ducklings fed a ration containing 700 mg of furazolidone/kg of feed for 27 days. A control group (n = 25) was fed the same ration without added furazolidone. Every 3 days, ducklings were weighted and palpated for ascites and 3 were chosen at random for euthanasia to determine the severity of lesions and to obtain hearts for gross measurements and ultrastructural study. Clinical alterations in treated ducklings consisted of decreased feed consumption with lower weight gain and nervous signs. Gross pathologic alterations included cardiomegaly with dilatation of all chambers and thinning of the myocardium, pericardial effusion, pulmonary edema and congestion, ascites, and testicular enlargement. Gross lesions were not observed before day 8. The earliest lesion (day 9) was cardiac chamber dilatation, with the left ventricle and left atrium most commonly and most severely dilated. Hearts from ducklings euthanatized on days 6, 12, 18, 24, and 27 were examined ultrastructurally. Myofibrillar lysis was first observed on day 12 in 1 duckling (of 3) and in at least 1 duckling from subsequent euthanasia periods. Myofibrillar lysis did not appear to be uniform among the cardiac chambers.

Reversibility of furazolidone-induced cardiotoxicosis in ducklings

Furazolidone cardiotoxicosis was induced in 2 groups (FZ and FZ-CR groups) of newly hatched male Pekin ducklings (100/group) by feeding a ration containing 650 mg of furazolidone/kg of feed (ppm) for 28 days. A third group (control ration, CR group; n = 100) was fed the same ration without furazolidone. On day 28, the control ration was initiated for the FZ-CR group initially given the furazolidone-containing ration, to allow recovery from the effects of the drug, whereas ducklings of the FZ group continued to consume the furazolidone-containing ration. Biweekly, beginning with week 4, ducklings were euthanatized to assess severity of gross lesions and to obtain sections of myocardium for histologic and ultrastructural examination. Clinical evidence (increased weight gain, increased feed consumption, decreased mortality, reduced prevalence of palpable ascites) of regression of cardiotoxicosis of ducklings of the FZ-CR group was nearly complete by day 56 (28 days after cessation of furazolidone intake). Likewise, regression of gross lesions, as measured by overall prevalence of gross lesions, left ventricular volume, and ascites prevalence and severity, were also essentially complete by day 56. Myofibrillar lysis was not seen in sections from the heart (examined ultrastructurally) obtained from ducklings of the CR group that were euthanatized on day 28, 56, or 98. Myofibrillar lysis was detected in all ducklings (4/4) fed furazolidone (FZ and FZ-CR groups) and euthanatized on day 28. Myofibrillar lysis was not seen in the heart of ducklings of the FZ-CR group that were euthanatized on day 56 or 98. Myofibrillar lysis was detected in the heart from all ducklings of the FZ group that were euthanatized on day 56.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular immune responses in pigs fed a vitamin E- and selenium-deficient diet

The effects of dietary restriction of vitamin E (Vit E) and selenium (Se) on lymphocyte proliferation, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and on burst respiratory response of stimulated granulocytes as measured by chemiluminescence (CL) were studied in pigs. Six male weanling pigs were maintained for 25 d on a torula yeast-based diet containing no measurable amount of alpha-tocopherol and less than .02 mg of Se per kilogram of feed. Six others received the same basal diet supplemented with 33 IU of DL-alpha-tocopheryl acetate and .2 mg of Se per kilogram of feed. All pigs were inoculated with Salmonella typhisuis on d 21 of the feeding period and killed on d 25. Tests to measure cellular immune functions were performed on cells isolated from blood samples taken on d 21 and 25. After 21 d of feeding, lymphocyte blastogenesis responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen in pigs fed the Vit E- and Se-deficient diet were normal compared with the response in pigs fed the supplemented diet. Moreover, the cytotoxic activity of NK cells, the ADCC response, and the CL response of granulocytes were not affected. After 25 d, a marked suppression of lymphocyte response to mitogens occurred in pigs fed the Vit E- and Se-deficient diet when the cells were cultured in the presence of autologous serum. When fetal bovine serum replaced autologous serum in the cultures, no suppression was observed. No effect on NK activity and ADCC was observed, whereas the CL peak response of granulocytes tended to be higher in pigs fed the deficient diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural alterations in furazolidone-induced cystic testicular degeneration in ducklings

Cystic testicular degeneration was induced in groups of ducklings by feeding furazolidone at 250, 400, 550, or 750 mg per kilogram of feed (ppm) for 4 weeks. In normal ducklings, tall, columnar Sertoli cells predominated in the seminiferous epithelium. In treated ducklings, the mildest ultrastructural alteration was cytoplasmic vacuolation of Sertoli cells. In birds with more severely affected tubules, cytoplasmic vacuolation was more severe and the cells were cuboidal or rounded. The rounded cells desquamated into the tubular lumens, eventually undergoing cytolysis. In birds with the most severely affected tubules, only extensively flattened epithelial cells lined the extremely dilated seminiferous tubules. The interstitium was edematous and compacted between the expanded tubules. Many of the testicular ultrastructural alterations in furazolidone-intoxicated ducklings were similar to those described in the testicles of sodium-intoxicated cockerels.

Cystic testicular degeneration in furazolidone toxicosis of sexually immature ducks

Cystic testicular tubular dilatation was seen in ducklings fed a ration containing furazolidone at 250, 400, 550, or 700 ppm for 28 days. Gross evidence of cystic testicular dilatation was observed at necropsy in 16% (32/203) of the ducklings that survived to the end of the study. Gross testicular lesions consisted of various degrees of enlargement with increased translucency in moderately to severely enlarged testicles. Histological evidence of cystic testicular dilatation was present in 45% (41/91) of the testicles examined. Histologically, the tubules were in various states of dilatation with attenuation of the seminiferous epithelium proportional to the severity of dilatation. In the most severely affected testicles, tubules were greatly dilated, distorted, and fluid-filled, with extensively flattened epithelium visible on the inner margin of the tubule as a thin rim of cytoplasm with a protuberant nucleus. Interstitial tissues were compressed to thin septa between the dilated tubules.

Furazolidone-induced injury in the isolated perfused chicken heart

The Langendorff isolated heart preparation was adapted to determine the effect of furazolidone (0.5 and 2 micrograms/ml of perfusate) on hearts of 3-week-old broiler chickens. Following 115 minutes of perfusion, both concentrations of furazolidone caused approximately a two-fold increase in myocardial vascular resistance and a six-fold increase in lactate dehydrogenase release into the effluent fluid, compared with a control perfused group of isolated hearts (P less than 0.01). Ultrastructural alteration differences were not found between the drug-treated and control groups. It was concluded that: (i) furazolidone, at concentrations only moderately above therapeutic plasma concentrations, caused detrimental changes in myocardial vascular resistance and lactate dehydrogenase release and (ii) the isolated chicken heart preparation is an example of a cost-effective, reliable laboratory tool for screening potential cardiotoxins.

Effects of dexamethasone elution on tissue reaction around stimulating electrodes of endocardial pacing leads in dogs

A pair of endocardial pacemaker leads, identical except for the presence or absence of dexamethasone elution from the distal stimulating electrode, was implanted into the right ventricle of each of 12 dogs for either 3 weeks (n = six pairs) or 6 weeks (n = six pairs). Fibrous connective tissue sheaths (0.04 to 0.20 mm thick) formed around the distal porous-surfaced stimulating electrodes because of proliferation of endocardial connective tissue and adherence and organization of thrombus. Connective tissue sheaths were composed of fibroblasts within an abundant collagen matrix and contained scattered macrophages, lymphocytes, plasma cells, and mast cells. Connective tissue sheaths around dexamethasone-eluting leads were thinner (p less than 0.03), less cellular (p less than 0.10), and had fewer mast cells (p less than 0.10) than corresponding nonsteroid leads. There was mild multifocal interstitial fibrosis, myofiber atrophy, and myofibrillar lysis in the adjacent myocardium. Thresholds for electrical stimulation of the myocardium were consistently lower for pacing leads with dexamethasone-eluting stimulating electrodes than for leads without dexamethasone.

Sequential ultrastructural changes of the pancreas in zinc toxicosis in ducklings

The sequential ultrastructural alterations of the pancreas in zinc toxicosis were examined in ducklings fed 2500 ppm Zn (as ZnSO4) for 56 days. From days 3 to 17, acinar cells had cytoplasmic vacuoles that contained electron-dense, zymogen-like material and increased autophagocytosis. Other changes were swollen mitochondria and dilatation, vesiculation, degranulation and intracisternal sequestration of rough endoplasmic reticulum. Apoptosis was the predominant form of cell deletion. By day 10, acinar cellular atrophy and interstitial fibrosis were noted. Islets appeared normal. After day 19, the pancreas consisted of ductlike structures embedded in fibrous connective tissue with a minimal inflammatory cell response. These ductlike structures were lined by attenuated to cuboidal, atrophic acinar cells. Many cells contained granular, electron-dense cytoplasmic debris that served as a marker of previous cell damage. This ultrastructural study provides support for a previously proposed theory that ductlike structures (tubular complexes) arise by atrophy and dedifferentiation of acinar cells.

Paired comparisons of steroid-eluting and nonsteroid endocardial pacemaker leads in dogs: electrical performance and morphologic alterations

The effects of steroid elution from endocardial pacemaker electrodes on electrical performance and the thickness and cellularity of the reactive fibrous connective tissue formed around the stimulating electrode (peri-electrode tissue) were determined. Comparison was made with a nonsteroid electrode implanted in the same cardiac chamber (right ventricle) in each of six dogs for 6 weeks. Paired Students' t-tests showed that steroid-eluting leads had significantly (P less than .05): (1) lower voltage stimulation thresholds (as determined in sequential measurements made on the conscious animals during the experiment and on the anesthetized dogs at termination of the study); (2) less fibrous connective tissue formation around the electrode surfaces; and (3) fewer cells per unit area of peri-electrode fibrous connective tissue. There were also fewer (P less than .10) mast cells in the reactive connective tissue surrounding steroid-eluting leads. The thinner reactive connective tissue surrounding the steroid-eluting electrodes was correlated with lower voltage stimulation thresholds (r = 0.7, P less than .01). This is consistent with the hypothesis that the effect of the peri-electrode connective tissue is to increase the virtual surface area of the electrode, decreasing current density in adjacent stimulatable tissue. The relatively fewer total cells and mast cells in the peri-electrode connective tissue of the steroid-eluting electrodes suggest that the observed differences in fibrous connective tissue thickness, and therefore voltage stimulation threshold, may be related to a relatively decreased population of inflammatory cells due to the anti-inflammatory properties of the steroid.

Monensin toxicosis in swine: potentiation by tiamulin administration and ameliorative effect of treatment with selenium and/or vitamin E

Modulation of acute monensin toxicosis in swine was evaluated in 2 studies. In study 1, 56 weanling male pigs were allotted to 14 groups of 4 each. Pigs in 7 groups were given tiamulin in the drinking water (to supply 7.7 mg/kg of body weight/day) for 3 days before and for 2 days after monensin administration. Monensin was given as a single oral dose (at 0, 7.5, 15, 25, 50, 75, or 100 mg/kg) to pigs in groups with or without tiamulin exposure. Prominent acute clinical signs of monensin toxicosis (hypermetria, hind limb ataxia, paresis, knuckling of hind limbs, and recumbency) developed by 2 to 6 hours after dosing in pigs given 15 or 25 mg of monensin/kg with tiamulin exposure, but not in pigs given the 15 or 25 mg of monensin/kg without tiamulin exposure. Also, the extent of monensin-induced skeletal muscle damage at 4 days after monensin dosing was enhanced in pigs given 7.5, 15, or 25 mg of monensin/kg and exposed to tiamulin. In study 2, 48 weanling male pigs were allotted to 8 groups of 6 each. Four groups of pigs were given 20 mg of monensin/kg orally, and 4 groups were given 100 mg of monensin/kg orally. For each monensin dose, a group was treated 24 hours before monensin administration with (i) selenium (Se)-vitamin E preparation, 0.25 mg of Se and 68 IU of d-alpha-tocopheryl acetate (vitamin E)/kg, IM; (ii) vitamin E only, 68 IU of d-alpha-tocopheryl acetate/kg; (iii) Se only, 0.25 mg of Se/kg; or (iv) vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)

Furazolidone-associated cardiomyopathy in two Indiana flocks of ducklings

Furazolidone (FZ)-induced congestive cardiomyopathy was diagnosed as the cause of high mortality and unthriftiness in two flocks of white pekin ducklings. Cumulative mortality at 7 weeks of age was 10.0-14.4%. Samples of FZ-supplemented feeds fed to flocks 1 and 2 from day 1 to day 14 had 140 and 150 mg FZ/kg, respectively. Both flocks had various degrees of water restriction. Clinically, the ducklings had dyspnea, incoordination, and abdominal distention. Necropsy findings included pulmonary edema and congestion, ascites, atrophic congested livers covered with sheets of fibrin, and cardiac enlargement with biventricular dilatation. Cardiac alterations were minimal by light microscopy. Ultrastructurally, scattered myocytes had myofibrillar lysis. These outbreaks occurred following intake of FZ at therapeutic dosages and emphasize the high susceptibility of young ducklings to FZ cardiotoxicity.

Ultrastructural changes in inherited cardiac calcinosis of DBA/2 mice

Cardiac dystrophic calcinosis, an inherited condition in DBA/2 mice, produced extensive calcific lesions in the right ventricular myoepicardium of affected mice. The morphogenesis of the cardiac alterations was evaluated by microscopic and ultrastructural studies. The initial event was necrosis and mineralization of subepicardial myocytes. Mineral deposits were seen as dense granular and spicular deposits in mitochondria only, mitochondria and adjacent sarcoplasm, or the entire sarcoplasm in necrotic myocytes. In mature myoepicardial calcific lesions, the remnants of necrotic myocytes were seen as scattered dense masses of mineralized debris with surrounding fibroplasia and occasional macrophages and giant cells. Male weanling DBA/2 mice (n = 135) were fed either a commercial diet adequate in selenium-vitamin E (Se-E) content, or a basal semipurified Se-E-deficient diet with or without silver acetate for 15, 20 or 25 weeks. Cardiac calcinosis severity seemed to increase in mice which developed concurrent Se-E deficiency. Cardiac calcinosis in the DBA/2 mouse is a useful model of cardiac calcification.

Myocardial diseases of animals

In this review we have attempted a comprehensive compilation of the cardiac morphologic changes that occur in spontaneous and experimental myocardial diseases of animals. Our coverage addresses diseases of mammals and birds and includes these diseases found in both domesticated and wild animals. A similar review of the myocardial diseases in this broad range of animal species has not been attempted previously. We have summarized and illustrated the gross, microscopic, and ultrastructural alterations for these myocardial diseases; and, whenever possible, we have reviewed their biochemical pathogenesis. We have arranged the myocardial diseases for presentation and discussion according to an etiologic classification with seven categories. These include a group of idiopathic or primary cardiomyopathies recognized in man (hypertrophic, dilated, and restrictive types) and a large group of secondary cardiomyopathies with known causes, such as inherited tendency; nutritional deficiency; toxicity; physical injury and shock; endocrine disorders, and myocarditides of viral, bacterial, and protozoal causation. Considerable overlap exists between each of the etiologic groups in the spectrum of pathologic alterations seen in the myocardium. These include various degenerative changes, myocyte necrosis, and inflammatory lesions. However, some diseases show rather characteristic myocardial alterations such as vacuolar degeneration in anthracycline cardiotoxicity, myofibrillar lysis in furazolidone cardiotoxicity, calcification in calcinosis of mice, glycogen accumulation in the glycogenoses, lipofuscinosis in cattle, fatty degeneration in erucic acid cardiotoxicity, myofiber disarray in hypertrophic cardiomyopathy, and lymphocytic inflammation with inclusion bodies in canine parvoviral myocarditis. The myocardial diseases represent the largest group in the spectrum of spontaneous cardiac diseases of animals. Pericardial and endocardial diseases and congential cardiac diseases are seen less frequently; and, in contrast to man, coronary artery disease and myocardial ischemia are rather infrequent in animals. The present review shows clearly that the spectrum of myocardial diseases in animals is enlarging and that many newly recognized diseases are emerging and assuming considerable importance. For example, various heritable cardiomyopathies have recently been described in the KK mouse, cattle, and rats. Increasingly recognized myocardial diseases include cardiomyopathies in cats, dogs, and birds; anthracycline cardiotoxicity; furazolidone cardiotoxicity; ionophore cardiotoxicity; myocardial damage associated with central nervous system injuries; myocardial hypertrophy in

Myocardial ultrastructural alterations in ducklings with isoproterenol-induced cardiotoxicosis

Fifty-two, 8-week-old, male White Pekin ducklings (Anas platyrhynchos domesticus) were allotted into control (n = 7) and isoproterenol-injected groups (n = 45). One control duck and 5 to 7 isoproterenol-injected (200 mg/kg of body weight) ducklings were euthanatized at postinjection hours (PIH) 1, 12, and 24 and at postinjection days (PID) 2, 4, 7, and 14. The left ventricular myocardium was examined, using electron microscopy. The earliest ultrastructural alteration in damaged myocytes was myofibrillar lysis at PIH 12. At PIH 24, affected myocytes had necrosis with mineralization of mitochondria. By PID 2, macrophages had invaded into areas of myocardial necrosis, mineralization was prominent in myocyte mitochondria, and dedifferentiated myocytes with reduced numbers of myofibrils, increased numbers of polysomes, large nuclei, and prominent nucleoli were first observed. The primary myocardial finding at PID 4, 7, and 14 was 2 populations of sublethally damaged myocytes. One population of injured myocytes had numerous polysomes in the sarcoplasm and large nuclei with prominent nucleoli, indicating attempts at repair of myofibrillar damage. The 2nd population of myocytes with myofibrillar lysis did not have morphologic evidence of myofibrillar repair. Therefore, the sequential ultrastructural alterations of damage and repair induced by isoproterenol in the duckling myocardium provided model for comparative studies of cardiotoxicity.

Effect of pretreatment with selenium-vitamin E on monensin toxicosis in cattle

Ten female beef calves weighing approximately 180 kg each were allotted to 2 groups of 5 each before they were given (orally) monensin (50 mg/kg of body weight). In group A, the calves were given (IM) a commercial selenium-vitamin E (Se-E) preparation (0.25 mg of Se and 17 IU of alpha-tocopherol/kg of body weight) at 72 and 24 hours before monensin was given. The calves in group B were injected at the 2 times with isotonic saline solution. Clinical signs of monensin toxicosis, including lethargy and recumbency, appeared on day 2 in the calves given the Se-E pretreatment, compared with the onset on day 1 in the saline solution-pretreated calves. All calves in the 2 groups died, but mean survival time was longer in group A (4.4 vs 2.2 days). Lesions of monensin toxicosis were myocardial necrosis, skeletal myonecrosis, pulmonary congestion, and rumenitis. The frequency and severity of the lesions were similar for both groups of calves. The results of the present study indicate that Se-E pretreatment modifies the development of monensin toxicosis in cattle.

Catheter electrode defibrillation in dogs: threshold dependence on implant time and catheter stability

A catheter-mounted electrode system designed for intracavitary ventricular defibrillation was implanted in the right ventricular apex of 12 dogs. Defibrillation thresholds were obtained in all dogs at the time of implant using an external defibrillator. Roentgenograms obtained 3 weeks after catheter implantation revealed that six dogs had catheters intact at the site of implant (group A) and six dogs had catheters that had dislodged from the original implant site (group B). There were no statistically significant differences (p less than 0.05) in mean body weight or mean defibrillation threshold between group A and group B dogs, respectively, at implant. Defibrillation thresholds were obtained for both groups of animals at 5, 12, and 26 weeks after catheter implantation. At all post implant monitors mean threshold for group B was significantly higher (p less than 0.05) than mean threshold for group A. Moreover, mean defibrillation threshold for both groups had increased by week 5 and remained stable through week 26. Catheter dislodgement increases defibrillation threshold, but does not prevent successful defibrillation. Also, defibrillation threshold increases to a stable value by 5 weeks post implant.

Cardiac lesions of selenium-vitamin E deficiency in animals

Necrosis of myocardium and skeletal muscle is a consistent finding in the numerous animal species in which spontaneous or experimental selenium-vitamin E (Se-E) deficiency has been described. Etiologic factors in the development of these lesions include: low dietary levels of Se, vitamin E, and sulfur-containing amino acids; high dietary concentrations of polyunsaturated fats; exposure to prooxidant conditions (toxicity by O2, O3, Fe, doxorubicin, and radiation injury); and intake of Se antagonists (Ag, Cu, Co, Cd, Te, Sb, and Zn). Myocardial lesions in Se-E deficient animals are most frequently seen in calves, lambs, turkey poults, and ducklings. In calves and lambs with cardiac lesions, the clinical finding usually is sudden death after vigorous exercise. At necropsy, affected calves have areas of necrosis and calcification in the left ventricular free wall and ventricular septum, while in lambs these lesions are seen in the right ventricular subendocardium. Histologically, areas of myocardial damage have hyaline necrosis with or without calcification, subsequent macrophagic invasion, and eventual fibrosis. In growing pigs, the hearts may have scattered pale streaks in the ventricular myocardium, but the most striking alterations are widespread epicardial and myocardial hemorrhages ("mulberry heart"). Histologically, both vascular and myocyte lesions are present. Vascular changes include fibrinoid necrosis of small arteries and arterioles and fibrin microthrombi in capillaries. The myocyte lesions in pigs and in birds consist of multifocal hyaline necrosis with calcification, followed by macrophagic invasion and fibrosis. Ultrastructural study of these lesions reveals myocyte alterations, which include mitochondrial swelling and mineralization, myofibrillar lysis, and necrosis with contraction bands.

Poikilocytosis in dogs with chronic doxorubicin toxicosis

Peripheral blood smears made during 2 studies of chemical antidotes for doxorubicin (DRB) cardiotoxicity in dogs were examined to determine the incidence of poikilocytosis. The 1st study had significantly (P less than 0.05) increased numbers of poikilocytes in 3 groups of 5 dogs, each treated with DRB alone, DRB plus thyroxine (0.5 mg/day), and DRB plus thyroxine (2.0 mg/day), respectively, compared with 1 group of 5 dogs treated with thyroxine alone (2.0 mg/day). In addition, the DRB-treated dogs had regenerative anemia characterized by an increased reticulocyte index. The 2nd study had a significant (P less than 0.05) increase in poikilocytes in 4 groups of 6 dogs, each treated with DRB alone, DRB plus +/- -1,2-bis(3-5-dioxopiperazinyl-1-yl; ICRF-187), DRB plus N-acetylcysteine (NAC), and drb plus ICRF-187 plus NAC, respectively, compared with 4 groups of 3 dogs, each treated with ICRF-187 plus saline solution (SS), NAC plus SS, ICRF-187 plus NAC plus SS, and SS alone, respectively. In both studies, the poikilocytes were identified as echinocytes, spiculated erythrocytes, and schizocytes. Administration of thyroxine and ICRF-187 did not prevent the occurrence of poikilocytosis in DRB-treated dogs. Administration of NAC with DRB resulted in a mild decrease in the extent of poikilocytosis compared with that observed in dogs given DRB alone. The hematologic changes observed in both studies were not accompanied by adverse clinical signs referable to the DRB-induced alterations in erythrocytes.

Comparison of the effectiveness of (+/-)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane (ICRF-187) and N-acetylcysteine in preventing chronic doxorubicin cardiotoxicity in beagles

This investigation examined the potential of N-acetylcysteine (NAC) and ICRF-187, alone and in combination, to protect against chronic doxorubicin cardiotoxicity. Adult beagles of either sex (7.3 to 12.5 kg) were given doxorubicin (1.75 mg/kg i.v.) either alone or 30 min after either ICRF-187 (25 mg/kg i.p.), NAC (200 mg/kg i.p.), or ICRF-187 (25 mg/kg i.p.) and NAC (200 mg/kg i.p.) at 3-week intervals. Control dogs received ICRF-187 (25 mg/kg i.p.), NAC (200 mg/kg i.p.), ICRF-187 (25 mg/kg i.p.) and NAC (200 mg/kg i.p.), or 0.9% NaCl solution without doxorubicin. The experiment was terminated 3 weeks after the seventh injection (total doxorubicin dose, 12.25 mg/kg). Three animals pretreated with NAC and one pretreated with ICRF-187 before receiving doxorubicin died or were in poor condition and were killed before the end of the study. The frequency and extent of myocardial lesions (vacuolization and myofibrillar loss) were assessed on a scale of 0 to 4+. Such lesions were present in all six dogs given doxorubicin alone and were marked to severe (3+ to 4+) in five of these dogs and moderate (2+) in one. Lesions of comparable severity (2+ to 4+) were also apparent in the hearts of dogs given the combination of NAC and doxorubicin. In contrast, no abnormalities (lesion score 0) were found in the hearts of three of six dogs given doxorubicin and ICRF-187 and in four of six dogs given doxorubicin following the combination of ICRF-187 and NAC; the remaining animals in these two groups had minimal lesions. At the dosage regimen used in the present experiments, doxorubicin, NAC, or ICRF-187 alone or in combination did not cause alterations in lungs, liver, kidney, or small intestine. Decreases in WBC count, RBC count, and hemoglobin occurred in dogs given doxorubicin with or without the various pretreatments. Thus, pretreatment with ICRF-187 was effective and pretreatment with NAC was ineffective in reducing chronic doxorubicin cardiotoxicity.

Cardiac morphologic alterations in acute minoxidil cardiotoxicity in miniature swine

Minoxidil, a vasodilating antihypertensive drug, was given orally at 10 mg/kg daily for 2 days to twelve 25- to 35-kg miniature pigs. Twelve control pigs were also studied. Minoxidil-treated pigs had tachycardia and hypotension and were killed 24 hr after the second dose. Gross examination showed diffuse hemorrhage in left atrial epicardium in all pigs, and also in ventricular epicardium (2 of 12 pigs) and endocardium (3 of 12 pigs). Pale areas of necrosis were observed on incision of the left ventricular papillary muscles in 3 pigs. Light and electron microscopic studies showed acute vascular damage with hemorrhage in the left atrial epicardium. Affected arterioles had endothelial cell swelling and transmural and perivascular accumulations of leukocytes, edema fluid, fibrin clumps, and erythrocytes. The swollen endothelial cells had large, irregularly shaped nuclei with abundant euchromatin; mitotic figures were frequent. The cytoplasm contained numerous polysomes and cisterns of rough endoplasmic reticulum. Fibroblasts adjacent to damaged vessels had edematous cytoplasm and increased amounts of rough endoplasmic reticulum. In the affected left ventricular papillary muscles, necrotic myocytes showed contraction bands, mitochondrial matrical densities, lipid accumulation, initial lysis of I bands, and pyknotic nuclei. The lesions were judged to result from two mechanisms: (1) hemorrhagic lesions from drug-induced vascular injury centered on epicardial and subepicardial arterioles and (2) papillary muscle necrosis from ischemic injury from hypoperfusion during minoxidil-induced tachycardia and hypotension.

Electrical stimulation on skin wound healing in the horse: preliminary studies

The effect of low-level direct-current stimulation on skin wound healing in the horse was assessed. Self-sustaining electrical circuits with electrodes were implanted subcutaneously in or near the wound. Stimulation by direct current (10 or 20 microA) was used to determine the effect on equine skin healing. The efficacy of electrotherapy was evaluated by sequentially comparing the clinical appearance of the wound and measuring the size of the granulating wound bed. The histologic appearance of the healing stimulated wounds was compared with that in nonstimulated control wounds created on 9 horses. Seemingly, electrical stimulation had no discernible effect on experimentally created skin wounds. Clinical observation and histologic examination of the wounds indicated that severe tissue reaction from the implanted electrodes and concurrent local infection produced local detrimental effects to wound healing.

Ultrastructural alterations in the atrial myocardium of pigs with acute monensin toxicosis

Monensin, A Na+-selective carboxylic ionophore, produces left atrial damage in pigs given toxic doses. Eight weanling pigs were given mycelial monensin orally (40 mg/kg body weight) and were killed on days 1, 2, 4, and 16 (two animals at each time interval) for ultrastructural study of the left atrial lesions. On days 1-4, extensive necrosis with contraction bands was present. Rapid macrophagic invasion and phagocytosis of sarcoplasmic debris was seen on days 2 and 4. Missing necrotic myocytes were outlined by persistent "tubes" of external laminas. In some surviving myocytes, sublethal injury was evident on day 1 by mitochondria with condensed conformation and on days 2, 4, and 16 by moderate to marked myofibrillar lysis and sarcoplasmic vacuolation. Monensin cardiotoxicity in pigs constitutes a unique example of selective injury to atrial myocardium.

Ultrastructural alterations in skeletal muscle of pigs with acute monensin myotoxicosis

Large doses of monensin, a Na+-selective carboxylic ionophore, produce polyfocal, monophasic necrosis of skeletal muscle, with Type I fiber selectivity, in swine. For a study of the sequential ultrastructural alterations in affected skeletal muscles, 14 weanling pigs were given 40 mg monensin/kg body weight and were euthanatized 1, 2, 4, 8, and 16 days later. Myotoxicosis and myoglobinuria were apparent clinically. At necropsy, white, dry areas of necrosis were present in the muscle masses of the anterior and posterior thigh, shoulder, and loin. Two patterns of skeletal muscle necrosis were observed on Day 1, especially in Type I fibers. In fibers exhibiting the first of these patterns, the contractile material was disrupted, forming dense amorphous and filamentous clumps scattered within the persistent sheaths of external lamina (sarcolemmal tubes); the mitochondria were swollen and contained flocculent matrix densities, and the nuclei were pyknotic. Fibers showing the second pattern were uniformly dense, but their sarcoplasm was not disrupted. Sublethally injured fibers were also observed and showed focal myofibrillar lysis. On Days 2 and 4, the necrotic muscle had marked infiltration of macrophages in the interstitium and within sarcolemmal tubes. Rapid resolution of the fiber necrosis occurred by phagocytosis of the sarcoplasmic debris. Regeneration of affected muscles developed early following injury and progressed rapidly to complete restoration of the necrotic muscles without residual fibrosis. Regeneration was initiated on Day 1 by activation of satellite cells to form presumptive myoblasts; on Days 4 and 8 these cells showed evidence of fusion, forming myotubes to restore the necrotic fibers.

Plasma coagulation factor abnormalities in dogs with naturally occurring hepatic disease

The plasma values for factors (F)VII, FVIII:C, FVIIIR:Ag, FIX, FX, and FXI and the thrombin clotting time (TCT) were determined for 28 dogs with naturally occurring hepatic disease. The major morphologic type of hepatic disease present in a given dog, as determined by hepatic biopsy and histopathologic examination, was degeneration (12 dogs), inflammation (9 dogs), cirrhosis (3 dogs), or neoplasia (4 dogs). A specific morphologic diagnosis also was made for each dog in the study. Plasma coagulation factor values and screening tests were consistently abnormal in greater than 50% of the dogs with each type of hepatic disease as follows: degeneration--decreased FXI; inflammation--increased FVIIIR:Ag; cirrhosis--shortened TCT, decreased FIX, FX, and FXI, and increased FVIIIR:Ag; and neoplasia--shortened TCT, decreased FVIII:C, and increased FVIIIR:Ag. The plasma coagulation factor values were compared with serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, fibrinogen-fibrin degradation product (FDP) concentration, and the prothrombin time (PT) and activated partial thromboplastin time (APTT) to determine the sensitivity and specificity of each test in detection of hepatic disease. Of all dogs with hepatic disease, 93% had at least 1 abnormal coagulation test value. The PT and APTT were abnormal in 50% and 75%, respectively, of these same dogs. Increased serum ALT and ALP activities were present in 61% and 50%, respectively, and FDP concentrations were increased in 14% of dogs with hepatic disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical, clinicopathologic, and pathologic alterations in acute monensin toxicosis in cattle

Twenty beef calves weighing approximately 180 kg were allotted to 3 groups. In group A, 6 calves were given 25 mg of mycelial monensin/kg of body weight orally and were evaluated at 1, 2, and 4 days for clinical, ECG, clinicopathologic, and pathologic alterations. In group B, 7 calves were given a single dose of monensin (40 mg/kg) and 5 were given a 2nd 40 mg/kg dose on day 7; calves were evaluated at days 1, 2, 4, 7, 8, 9, and 11. In group C, 2 calves served as controls. Monensin-treated calves developed anorexia, diarrhea, and lethargy after day 1. One group B calf died on day 7 with lesions of congestive heart failure. Electrocardiographic abnormalities were not observed in group A calves; in group B, prolongation of Q-T and QRS intervals occurred from days 2 to 11 and first degree heart block was seen from days 7 to 11. Clinicopathologic alterations included: increased serum activities of aspartate aminotransferase and creatine kinase in group B calves after day 2; decreased serum K+, Na+, and Ca2+ concentrations in both groups, and postdosing occurrence of leukocytosis. Calves were euthanatized sequentially and the lesions of monensin toxicosis were present in the heart, skeletal muscles, and rumen in groups A and B. Disseminated pale yellowish-brown areas of necrosis were present in the ventricular myocardium of 6 of 12 group B calves. Gross lesions were not present in the skeletal muscles or rumen. Microscopically, the myocardial and skeletal muscular lesions were characterized by sarcoplasmic vacuolation from mitochondrial swelling and lipid accumulation in calves killed after day 1 in groups A and B, and by myocardial necrosis with contraction bands, but without calcification, in group B calves killed by day 4. Acute rumenitis was present in groups A and B calves. Myotoxic effects of monensin may be related to its action as an ionophore producing altered intracellular ion concentrations and initiating degeneration and necrosis in striated muscle fibers.

Furazolidone-induced congestive cardiomyopathy in ducklings: regression of cardiac lesions after cessation of furazolidone ingestion

Newly hatched male White Pekin ducklings (n = 92) were allotted to 2 groups of 46 each and fed 750 mg of furazolidone (FZ)/kg of feed either for 8 weeks (group 1) or for 4 weeks followed by 4 weeks of no FZ intake (group 2). Regression of FZ-induced toxicosis was observed in ducklings of group 2 after cessation of FZ consumption, as evidenced by decreased mortality, progressive decrease in ascites, and increases in body weight gains. Necropsy of 8-week survivors revealed decreased frequency and severity of ascites in ducklings of group 2. The severity of FZ-induced cardiac alterations also was diminished, with a decrease in left ventricular dilatation score and an increase in absolute heart weights in 8-week survivors in group 2. Further evidence of regression of FZ-induced congestive cardiomyopathy after cessation of FZ ingestion was gained from development of intermediate cardiac damage severity scores and frequency and severity of ascites at necropsy in ducklings (previously studied) examined after 4 weeks of FZ feeding, compared with those found in group 1 (FZ 8 weeks) or in group 2 (FZ 4 weeks, no FZ 4 weeks) of the present study. Furazolidone-induced cardiac disease in ducklings offers an attractive model for studies of the pathogenesis of congestive cardiomyopathy and cardiac failure.

Furazolidone-induced congestive cardiomyopathy in ducklings: lack of protection from selenium, vitamin E, and taurine supplements

Newly hatched male White Pekin ducklings (n = 108) were allotted to 6 groups of 18 each and were fed for 4 weeks diets containing 750 mg of furazolidone (FZ)/kg of feed either alone or with supplements of vitamin E (250 IU of dl-alpha-tocopheryl acetate/kg), selenium (2.5 mg as selenite/kg) or taurine (1%). Control groups were fed diets without FZ and with or without added taurine (1%). Ducklings in the 4 FZ-fed groups had retarded growth, mortality, ascites, and cardiac alterations of congestive cardiomyopathy. Supplements of vitamin E, selenium, or taurine did not protect against the development of the cardiac and extracardiac alterations of FZ toxicosis. These findings could indicate that the development of FZ-induced congestive cardiomyopathy is not mediated by low tissue concentrations of selenium, vitamin E, or taurine.

Furazolidone-induced congestive cardiomyopathy in ducklings: myocardial ultrastructural alterations

Newly hatched male White Pekin ducklings were fed furazolidone (FZ) at dosage of 750 mg/kg of feed for 4 weeks. Selected ducklings with advanced lesions of FZ-induced congestive cardiomyopathy were used for ultrastructural study of the myocardial alterations. Semithin sections of plastic-embedded blocks of myocardium from these dilated hearts revealed diffuse myocytolysis, characterized by pale sarcoplasm and lack of cross-striations in affected myocytes. Evidence of myocardial necrosis, inflammation, or fibrosis was not observed. Ultrastructural study revealed that the principal alteration in cardiac muscle cells was diffuse myofibrillar lysis. The sarcoplasm of affected myocytes had scattered masses of free thick and thin myofilaments, clumps of Z-band material, and accumulations of cytoskeletal filaments. Numerous polyribosomes were present in the areas of lysis of contractile material, as were other normal-appearing organelles. Myofibrillar lysis may have resulted from FZ-induced decreased synthesis, increased degradation, or disaggregation of contractile proteins. Ducklings with FZ-induced congestive cardiomyopathy offer an attractive model for studies of the biochemical and ultrastructural alterations of myofibrillar lysis and drug-induced cardiac failure.

Skin burns from electrosurgical current

At 34 skin sites on anesthetized pigs, graded levels of average electrosurgical current density, J (A/cm2), at 500 kHz were delivered for specified times (t sec) to cause thermal injury. The severity of cutaneous response was determined by gross and microscopic study 56 hours later. The product J2t has been defined as the relative energy density factor, and is proportional to the delivered energy that determines skin heating. Nine of 10 sites that received low energy density factor exposure (J2t = 0.20-0.70 A2/cm4.sec-1) exhibited maximum skin temperatures of 38-47 degrees C beneath the electrodes, and subsequently has either no damage or as mild second-degree burn lying just beyond the electrode contact zone. At 9 of 11 sites exposed to a medium energy density factor (J2t = 0.70-1.60), the maximum skin temperatures below the electrodes were between 49 and 55 degrees C, with single or multiple rings of second-degree burns located just inside or beyond the rim of the electrode. At all 13 sites exposed to high energy density (J2t = 1.60-7.50), the maximum skin temperatures beneath the electrodes were 55-81 degrees C, and severe burns were produced with white to brownish, dry, firm, third-degree burns surrounded by peripheral rings of second-degree burns. No significant skin damage was produced with skin temperatures less than 45 degrees C (an energy density factor of 0.75). These data identify the temperature and energy density factor necessary to produce lesions on porcine skin.

Alterations induced by a single defibrillating shock applied through a chronically implanted catheter electrode

In ten beagles ranging in weight from 7.4 to 13.0 kg, a defibrillating shock of 10 A (three dogs), 20 A (four dogs), or 30 A (three dogs) intensity was applied through a chronically implanted right ventricular catheter electrode. Ten-lead ECG, right ventricular electrogram, and right ventricular impedance were recorded prior to, immediately following, and 48 hours post-shock. A single shock of 10 A, 20 A, and 30 A intensity succeeded in defibrillating nine of ten dogs. One dog required two 20 A shocks to defibrillate. No shock was fatal. Post-shock arrhythmias increased in duration and severity as the shock strength increased. ECG vector analysis suggested damage to the right ventricle in eight of ten dogs. The impedance signal amplitude increased directly after the shock, but dropped below control level by 200 seconds post-shock and remained below control by 48 hours post-shock. Pale areas of shock-induced myocardial necrosis were concentrated in the right ventricular walls adjacent to the distal electrode. The mean weight of necrotic myocardium was 0.043 + 0.006 grams at 10 A, 1.203 + 0.268 grams at 20 A, and 1.397 + 1.218 grams at 30 A (mean + sd). Defibrillation was effective after long-term implantation. The alterations sustained from defibrillation were minimized by using a low intensity shock.

Congestive cardiomyopathy induced in ducklings fed graded amounts of furazolidone

Newly hatched male White Pekin ducklings (n = 119) were allotted to 7 groups of 17 each and fed furazolidone (FZ) at dose levels of 0, 100, 250, 500, 750, 1,000, and 1,250 mg/kg of feed for 4 weeks. The frequency and severity of clinical signs of FZ toxicosis, including growth retardation, ascites, and mortality, were dose related. At necropsy, the affected ducklings had ascites, hydropericardium, and biventricular dilatation. The frequencies of cardiomyopathy, ascites, and mortality, respectively, for the several dose levels of drug were as follows: 0, 100, and 250 mg of FZ/kg of feed--0%, 0%, 0%; for the 500 mg/kg level--35%, 12%, 0%; for the 750 mg/kg level--100%, 53%, 18%; for the 1,000 mg/level--79%, 57%, 57%; and for the 1,250 mg/kg level--33%, 20%, 73%. Ducklings with FZ-induced congestive cardiomyopathy had decreased left ventricular free wall and ventricular septal thickness, increased left ventricular chamber diameter, increased left ventricular dilatation score, decreased absolute heart weight, and increased relative heart weight. Cardiac histopathologic changes were minimal; some ducklings had myocytolysis. Liver and lungs were congested. Furazolidone-induced cardiomyopathy in ducklings offers a model for studies of congestive cardiomyopathy in a species that is free from the hereditary cardiomyopathy ("round heart disease") seen in turkeys.

Effect of thyroid hormone supplementation on chronic doxorubicin (adriamycin)-induced cardiotoxicity and serum concentrations of T3 and T4 in dogs

Chronic doxorubicin (adriamycin; ADR) intoxication was produced in Beagle dogs by weekly IV injections (1 mg/kg of body weight) for 20 weeks (cumulative dose 400 mg of ADR/m2). Group A (5 dogs) were given ADR only; group B (5 dogs), ADR and daily supplements of 0.5 mg of L-thyroxine (T4) (twice the recommended maintenance dose); and group C (5 dogs), ADR and 2.0 mg of T4 daily (8 times the recommended maintenance dose). The control group D (5 dogs) was given 0.5 mg of T4 daily. The ADR-induced cutaneous lesions (alopecia and melanosis), body weight loss, hematologic alterations, and myocardial microscopic and ultrastructural alterations (sarcoplasmic vacuolation and myocytolysis) were present with equal severity in the 3 ADR-treated groups, with or without T4 supplements. Six of the 15 ADR-treated dogs died during the study: 3 dogs had pneumonia, 1 dog had no established cause of death, and 2 dogs (from group C) had lesions of congestive cardiac failure. All ADR-treated dogs given a cumulative dose of 340 mg of ADR/m2 or more had characteristic myocardial histopathologic alterations, but 2 dogs that died after they were given only 140 or 260 mg of ADR/m2 had no microscopic evidence of myocardial damage. Low serum triiodothyronine (T3) concentrations were present in ADR-treated dogs after 28, 56, 84, 112, and 140 days and were attributed to faulty extrathyroidal conversion of T4 to T3. Serum T4 concentrations were high in dogs given 2 mg of T4/day (group C) after 28, 56, 84, and 112 days, but were low terminally as those dogs became debilitated from chronic ADR toxicosis. Unusual clinical signs or cardiac alterations of hyperthyroidism did not develop in the dogs given T4 supplements (groups B, C, and D). Our findings indicate that supplements of T4 do not alter the development of the cardiac and extracardiac lesions of chronic ADR toxicosis in dogs and indicate that the ADR-induced lesions probably are not mediated via hypothyroidism.

Myocardial ultrastructural alterations in ducklings fed tellurium

Seventy newly hatched ducklings were fed a commercial ration with 500 mg of added Te (as tetrachloride)/kg of feed for up to 28 days. Ducklings were euthanatized at day 14, 21, and 28, the hearts were studied by gross, microscopic, and ultrastructural examination. Cardiac damage was apparent grossly as hydropericardium and myocardial hemorrhage. Histopathologically, the ventricular myocardium had areas of acute hemorrhagic necrosis (often with mineralization), edema, and congestion. Resolving areas of necrosis appeared cellular with macrophages, heterophils, fibroblasts, and pale vacuolated cells with large vesicular nuclei that were identified as dedifferentiated myocytes. Ultrastructurally, necrotic fibers had disrupted contractile material and mineralized mitochondria. In resolving lesions, macrophages were numerous in the interstitium and within necrotic fibers. Also, a population of sublethally injured myocytes was present and appeared as dedifferentiated cardiac muscle cells with few myofibrils, scattered free filaments, prominent sarcoplasmic reticulum, abundant glycogen, and large nuclei with prominent nucleoli. These dedifferentiated myocytes represented a reparative phase of the Te-induced myocardial injury which has been termed "reactive hyperplasia" and "rejuvenating reorganization" in previous models of myocardial damage.

Amounts of twelve elements required to induce selenium-vitamin E deficiency in ducklings

Mortality and myopathy of selenium-vitamin E (Se-E) deficiency was produced, in a concentration-dependent pattern, during a 4-week study of 750 ducklings fed a commercial duck starter mash that contained adequate amounts of Se and E, and supplemented with multiple amounts of Ag (50 to 3,000 mg/kg of feed, as acetate), Zn (3,000 to 6,000 mg/kg, as sulfate), Cd (10 to 500 mg/kg, as sulfate), Te (25-500 mg/kg, as tetrachloride), Co (100 to 1,000 mg/kg, as chloride), Cu (500 to 1,500 mg/kg, as sulfate), Hg (200 to 400 mg/kg, as chloride), and Sn (1,000 mg/kg, as chloride). Also, feeding supplements of Pb (500 mg/kg, as acetate), As (600 mg/kg, as sodium arsenilate), Fe (5,000 mg/kg, as sulfate), and S (5,000 mg/kg, as sodium sulfite) produced a low-to-medium frequency of lesions of Se-E deficiency. In ducklings with muscle lesions, the gizzard was most often affected (84.2%), followed in decreasing order by skeletal muscles (69.7%), intestine (34.9%), and heart (23.0%). The frequency of skeletal muscle lesions was high in birds fed Ag, and myocardial necrosis was frequent in ducklings fed Te and Hg. Ducklings affected with myopathy were reluctant to stand. Subcutaneous edema, with or without hemorrhages, and pale areas of myonecrosis in gizzard, skeletal muscles, intestine, and heart were seen at necropsy. Birds fed Te and Hg often had hydropericardium and hemorrhagic myocardial necrosis. Seemingly, addition of many elements to a Se-E adequate commercial diet will increase the requirement for Se-E. In our duckling model, minimal amounts shown to induce Se-E deficiency were 50 mg of Ag/kg, 3,000 mg of Zn/kg, 10 mg of Cd/kg, 25 mg of Te/kg, 1200 mg of Co/kg, 500 mg of Cu/kg, 200 mg of Hg/kg, 1,000 mg of Sn/kg, 500 mg of Pb/kg, 600 mg of As/kg, 5,000 mg of Fe/kg, and 5,000 mg of S/kg.

Ultrastructural alterations in the fibrous sheath, endocardium, and myocardium of dogs shocked with chronically implanted automatic defibrillator leads

Catheter-mounted automatic implantable defibrillator leads were implanted in 10 dogs for 11 to 21 months (mean 15.0 months). Single shocks of 10 A, 20 A, or 30 A (peak current) were then delivered through the chronically implanted leads. Two days after the shock, the dogs were euthanatized and necropsied. The intracardiac segment of the lead was covered by a fibrous sheath, the endocardium in contact with the lead was thickened by fibrous tissue, and shock-induced myocardial necrosis was present surrounding the distal pair of electrodes, with the largest amount of damage found in the dogs given the large shocks. Ultrastructurally, the fibrous sheath was covered by endothelium and contained numerous spindle cells and identified as smooth muscle cells by their prominent cytoplasmic filaments and external laminae or myofibroblasts with prominent endoplasmic reticulum. The spindle cells were surrounded by abundant collagen fibrils but not by elastic fibers. The thickened endocardium contained numerous fibroblasts, abundant collagen fibrils, and a few small elastic fibers. The shock-induced myocardial alterations included necrosis of cardiac muscle cells with prominent mitochondrial mineralization, interstitial edema, and infiltration of macrophages.

Tissue gamma-glutamyl transpeptidase activity and hepatic ultrastructural alterations in dogs with experimentally induced glucocorticoid hepatopathy

Glucocorticoid hepatopathy was induced in 2 Beagle dogs with IM injections of prednisone, 4.4 mg/kg, given once daily for 14 consecutive days. Serum enzymatic activities were monitored and percutaneous hepatic biopsy materials were collected. A placebo-treated group of 2 Beagle dogs was given saline solution injections. Treated dogs showed clinical signs of Cushing's disease and alterations in mean serum enzymatic activities consistent with glucocorticoid hepatopathy. The gamma-glutamyl transpeptidase activities in placebo-treated dogs were highest for kidney, less (but marked) for pancreas, and least for liver, gallbladder, jejunum, duodenum, spleen, heart, lung, skeletal muscle, and erythrocytes. In treated dogs, the gamma-glutamyl transpeptidase activities were highest for pancreas and were decreased for kidney and slightly increased for the other tissues. Results of hepatic biopsy and necropsy examinations of treated dogs showed swollen, pale, friable hepatic parenchyma with hepatocytic cytoplasmic vacuolation and glycogen accumulation. Extrahepatic lesions included gastric ulceration, catarrhal enteritis, splenic and lymph node atrophy and lymphocytolysis, and vacuolation of adrenal cortical cells in the zona fasciculata. Ultrastructural study of liver from dogs with glucocorticoid hepatopathy indicated that the principle alterations were abundant glycogen accumulation and few mitochondria in hepatocytes.

Alterations of prothrombin time and activated partial thromboplastin time in dogs with hepatic disease

Reference intervals for prothrombin time (PT) and activated partial thromboplastin time (APPT) of undiluted and serial dilutions of citrated platelet-poor plasma were determined for 30 healthy dogs. The PT and APTT were similarly determined for 32 dogs with naturally occurring hepatic disease. Hepatic disease was confirmed by histopathologic examination of hepatic biopsy materials and comprised degeneration (13 dogs), inflammation (11 dogs), cirrhosis (4 dogs), and neoplasia (4 dogs). Coagulation test values were compared with serum alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase activities and Bromsulphalein retention for sensitivity in detecting hepatic disease in the dog. Coagulation test results were at variance with reference values in 66% of the 32 dogs with hepatic disease; serum alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase were increased in 59%, 72%, and 75%, respectively and Bromsulphalein retention was increased in 22% of the 32 dogs. Thus, the PT and APTT were sensitive indicators of hepatic disease. However, the PT and APTT lacked specificity for any given hepatic disease. The sensitivity of the coagulation tests for detecting hepatic disease was enhanced by using dilutions of citrated platelet-poor plasma. Only 15% of dogs with hepatic disease showed variances from reference values in the coagulation tests done with undiluted plasma, but 66% showed variances in the tests with dilutions of plasma. Coagulation tests were also done in 13 dogs with normal hepatic function amd morphology, but with various extrahepatic diseases: chronic renal disease (5 dogs), dirofilariasis (4 dogs), encephalitis (1 dog), cutaneous disease (2 dogs), and femoral fracture (1 dog). Twelve of the 13 dogs had coagulation test values within the reference intervals.