Lasalocid Toxicity in Cattle: Acute Clinicopathological Changes2

Abstract

Thirty-six steers (148 to 500 kg) divided into six equal groups were used in a toxic syndrome study of lasalocid and monensin given as a single oral dose. One group was given a placebo, a second group received monensin (25 mg/kg body weight) and the other four groups received lasalocid at 1, 10, 50 or 100 mg/kg body weight (bw). No toxic signs developed in cattle given placebo or lasalocid at 1 or 10 mg/kg bw dose. The earliest toxic signs were muscle tremors, tachycardia and rumen atony. After 24 h, the cattle were dehydrated, anorectic and had diarrhea. Deaths occurred between d 1 and 22.5 in the groups receiving lasalocid at 50 and 100 mg/kg bw and monensin. Altered values in blood leucocytes, erythrocytes, hemoglobin, hematocrit, total protein, albumin, creatinine, urea nitrogen, total bilirubin, creatine kinase, lactic dehydrogenase, calcium, chloride and inorganic phosphate occurred 1 d after dosing: urine pH and specific gravity also changed 1 d after dosing. Maximum changes occurred at d 3. Most of the changes were indicative of dehydration rather than specific organ damage.

Cardiomyopathy in cattle induced by residues of the coccidiostat maduramicin in poultry litter given as a feedstuff

“…Experimental monensin poisoning in beef calves also resulted in marked rises in AST and CPK levels and these were regarded as being the most useful tests to detect tissue damage (Van Vleet et al, 1983). Reduced Ca 2+ concentrations as seen in group 2 heifers were also found in both monensin and lasalocid (another polyether ionophore) poisoning in cattle (Van Vleet et al, 1983;Galitzer et al, 1986). The elevated phosphorus concentrations in both the groups which had received maduramicin were also recorded in monensin poisoning (Van Vleet et al, 1983;Schweitzer et al, 1984).…”

Lasalocid Toxicosis in Dairy Calves

“…4,9 Experimentally, toxicosis with both compounds can produce myocardial necrosis and lesions of congestive heart failure. 3,4,6,9 Field cases of monensin toxicosis have been reported for cattle. 9,10 However, the authors are unaware of previous reports of field cases of lasalocid toxicosis in the bovine.…”

“…3,4,6 Clinical signs included anorexia, increased respiratory and heart rates, and watery diarrhea with death occurring 6-10 days after dosing. Transient anorexia (2-3 days) and transient watery diarrhea (2-3 days) developed after single oral doses of 10-25 mg/kg bw.…”

Ionophores

“…Elevation of serum enzymes, notably creatine kinase, lactate dehydrogenase and aspartate transaminase, may indicate damage to cardiac and skeletal muscles (Amend et al, 1981;Van Vleet et al, 1983b,c;Galitzer et al, 1986b;Wilson, 1990). Alkaline phosphatase, inorganic phosphorus and total bilirubin levels are also higher, while serum levels of calcium and potassium are lower.…”