monensin and Muscular-Diseases

Monensin and vitamin E concentrations, as well as histopathology of skeletal muscles and myocardium, were evaluated in broad-breasted white turkeys kept in commercial facilities. Turkeys with knockdown syndrome had myopathy of skeletal muscles, but no lesions in the myocardium. Generally, concentration of monensin in serum was highest in turkeys diagnosed with knockdown syndrome given more than 90 mg/kg of monensin in the diet, followed by turkeys diagnosed with knockdown syndrome given <90 mg/kg of monensin in the diet, healthy turkeys fed a diet that contained <90 mg/kg of monensin, and finally healthy turkeys fed a diet free of monensin (not detectable). However, the concentration of monensin was highly variable within each group, and the median was lower than the average. Vitamin E concentrations in the livers varied from low-normal to below normal and were statistically higher in healthy turkeys fed a diet free of monensin than in the livers of birds from the 3 groups exposed to monensin. This suggests that the concentration of monensin in serum positively correlates to the severity of clinical signs and pathology and to the amount of monensin in the feed. Although the methodology developed to detect serum monensin concentrations is beneficial and accurate for case investigations, it is recommended that several samples from each flock be evaluated because of variation within a flock. The current study also suggests that monensin in the feed could induce lower concentrations of vitamin E in the liver of turkeys and can predispose the turkeys to knockdown syndrome.

Topics: Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Antiprotozoal Agents; Diet; Dietary Supplements; Drug Interactions; Liver; Monensin; Muscle, Skeletal; Muscular Diseases; Poultry Diseases; Turkeys; Vitamin E; Vitamins

The consumption of monensin-containing feed resulted in deaths of water buffaloes from a feedlot in which cattle and buffaloes were kept together. The monensin formulation was recommended only for use in cattle. Anorexia, muscular weakness, dyspnea, and recumbency were the major clinical findings. The most significant gross lesions were focal pale areas in semitendinosus and semimembranosus muscles, in which segmental necrosis of myofibers was seen microscopically. To compare susceptibilities of species to monensin, 3 bovine calves and 3 buffalo calves were orally dosed. At 5, 7.5, and 10 mg/kg of monensin, only the buffaloes became ill and died. Clinical signs initiated 18-20 h postdosing and were comparable to those from field cases. Gross changes consisted of ascites, hydrothorax, hydropericardium, hepatomegaly, and focal pale areas in the myocardium and to a lesser degree in semitendinosus and semimembranosus muscles. Histopathological changes also resembled those from the field cases, but were especially pronounced in the myocardial cells. The hypothesis that buffaloes could have a lower tolerance to monensin than cattle has been supported by experimental cases.

Topics: Animals; Anorexia; Buffaloes; Histocytochemistry; Ionophores; Monensin; Muscular Diseases

The effect of sodium ions (Na+) on calcium (Ca2+)-mediated muscle damage in broiler chickens was investigated using an in vitro muscle preparation. Muscle Ca2+ accumulation was determined by 45Ca2+ uptake. Muscle damage was assessed by measurement of the efflux of the intracellular enzyme creatine kinase (CK) into the incubation medium. Loading muscle cells with Na+ by means of the sodium ionophore monensin led to concentration-dependent (25 to 200 microM) increases in 45Ca2+ uptakes and corresponding and proportional CK losses. The greatest responses occurred at 100 microM ionophore or greater, reflected in a 49% increase (P < 0.05) in 45Ca2+ uptake and an associated 140%-fold increase (P < 0.001) in CK efflux. Inhibition of muscle Na+/K+-ATPase activity with ouabain (2 mM) induced a 56% increase in 45Ca2+ uptake and a 60%-fold increase (P < 0.001) in total CK loss. The combined use of ionophore and ouabain resulted in 90 and 130%-fold elevations in 45Ca2+ uptake and CK loss, respectively. In monensin-treated muscles, inhibition of external Ca2+ influx from the incubation medium by chelation with 1,2 bis(2-aminophenoxy)ethane-N,N,N',N' tetracetic acid (5 mM) markedly reduced 45Ca2+ uptake (38%: P < 0.05) but increased CK release by 85% (P < 0.001). The results demonstrate that initial elevations in muscle Na+ can facilitate increases in muscle Ca2+ and lead to alterations in muscle cell membrane integrity and CK loss. The Na+-induced increases in myocellular Ca2+ may be mediated via direct extracellular Ca2+ entry or redistribution from internal Ca2+ stores. It is proposed that in order to reduce or prevent myopathies in poultry, exposure to conditions that may lead to elevations in muscle Na+ (e.g., increased muscle activity and stress or accidental ionophore toxicosis) should be avoided. The findings of this study have implications for management strategies of bird welfare, muscle pathology, and product quality.

Topics: Animals; Biological Availability; Calcium; Calcium Radioisotopes; Chickens; Female; Monensin; Muscle, Skeletal; Muscular Diseases; Ouabain; Poultry Diseases; Sodium; Sodium-Potassium-Exchanging ATPase

Several lambs in 2 sheep flocks died suddenly and others were examined for generalized weakness and dyspnea. Postmortem findings were suggestive of degenerative myocardial and skeletal muscle myopathy, which was confirmed histologically. Feed analysis revealed toxic levels of monensin and ionophore toxicosis was diagnosed.

Topics: Animal Feed; Animals; Food Contamination; Ionophores; Monensin; Muscular Diseases; Sheep; Sheep Diseases

Topics: Animals; Calcium; Chickens; Creatine Kinase; Monensin; Muscle, Skeletal; Muscular Diseases; Poultry Diseases; Species Specificity

Topics: Animal Feed; Animals; Female; Monensin; Muscular Diseases; Poultry Diseases; Turkeys

An outbreak of muscle disease affected approximately 20 of 600 ewes in spring 1987 in south-east Scotland. The clinical signs were a flaccid paralysis of the hind limbs and in severe cases collapse. Serum creatine kinase and aspartate aminotransferase activities were increased. Clinically affected sheep had a mean reciprocal serum antibody titre in a sarcocystis immunofluorescence antibody test of 557 whereas 22 sheep from the same flock, sampled one year earlier, showed a mean reciprocal titre of only 51. Histologically a heavy infestation of sarcocysts, myodegeneration and a non-suppurative myositis centred on degenerating sarcocysts were observed in a wide range of skeletal muscles and myocardium from four affected sheep. Monensin sodium had been inadvertently included in the protein pellet used in the feed for one week before the onset of the disease.

Topics: Animal Feed; Animals; Antibodies, Protozoan; Disease Outbreaks; Female; Fluorescent Antibody Technique; Food Contamination; Heart; Monensin; Muscles; Muscular Diseases; Sarcocystis; Sarcocystosis; Scotland; Sheep; Sheep Diseases

Feedlot calves given monensin in their feed developed an excessive mortality which peaked 3-4 mo after monensin was withdrawn. Typically the calves died suddenly and necropsy revealed areas of paleness in the skeletal muscles (early cases) and in the myocardium (more chronic cases). Histology (in 19 calves) showed swollen myocytes with loss of striation and sarcoplasmic vacuolization, followed by the appearance of necrotic fibres and infiltration with macrophages and neutrophils, and finally local and generalized fibrosis. Calcification was not evident. A differential diagnosis ruled out an etiology of nutritional and toxicological origin, thus leaving the probability of atypical (chronic) monensin toxicosis.

Topics: Animal Feed; Animals; Cardiomyopathies; Cattle; Cattle Diseases; Foodborne Diseases; Furans; Male; Monensin; Muscles; Muscular Diseases; Myocardium

Topics: Animals; Cattle; Cattle Diseases; Furans; Male; Monensin; Muscular Diseases

Simultaneous administration of monensin and tiamulin to pigs resulted in enhanced myotoxicity. Skeletal muscles of tongue, diaphragm and legs were preferentially affected, whereas the masseter, longissimus thoracis and cardiac muscles, including the left auricle, were spared. Histochemical examination revealed an involvement of both type I and II fibers of skeletal muscles.

Topics: Animals; Anti-Bacterial Agents; Diterpenes; Drug Synergism; Food Additives; Furans; Histocytochemistry; Male; Monensin; Muscles; Muscular Diseases; Swine; Swine Diseases; Weaning

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.

Topics: Acute Disease; Animals; Female; Furans; Male; Mitochondria, Muscle; Monensin; Muscle Contraction; Muscles; Muscular Diseases; Necrosis; Regeneration; Sarcoplasmic Reticulum; Swine

Topics: Animals; Anti-Bacterial Agents; Diterpenes; Drug Interactions; Female; Furans; Male; Monensin; Muscular Diseases; Swine; Swine Diseases

This report describes a case of toxic myopathy in a two year old sheltie dog with clinical signs of profound weakness, myoglobinuria, and muscle enzyme elevations. The clinical signs were likely related to the accidental inclusion of monensin sodium in the dog's food. This food was prepared by a small feed milling company that also prepares cattle and chicken rations. A change of dog food resulted in remission of the clinical signs.

Topics: Animal Feed; Animals; Dog Diseases; Dogs; Furans; Monensin; Muscular Diseases