Toxicosis in Cattle from Concurrent Feeding of Monensin and Dried Distiller's Grains Contaminated with Macrolide Antibiotics

Abstract

Consumption of monensin-containing feed contaminated with macrolide antibiotic residues resulted in the death of cattle from multiple feedlots in south-central Kansas. Cattle were fed milo dried distiller's grains (DDG) with solubles from a common source in conjunction with the ionophore antibiotic, monensin. Deaths occurred as early as 72-96 hours after feeding and were preceded by either no premonitory signs or 1 or more of the following: anorexia, depression, dyspnea, locomotor deficits, and recumbency. Significant gross lesions were pulmonary and mesenteric edema, hepatomegaly, and generalized myocardial and skeletal muscle pallor that was confirmed histologically as acute myodegeneration and necrosis. Other significant histologic lesions included centrolobular hepatocellular necrosis, congestion, and pulmonary interstitial and alveolar edema with fibrin exudation. Animals that survived beyond 6 weeks had poor weight gain and coalescing foci of myocardial fibrosis with residual myocardial degeneration. Analysis of trace mineral supplements for monensin were within the manufacturer's label range. The DDG samples from affected feedlots had 50-1,500 ppm of erythromycin, clarithromycin, and related macrolide antibiotic analogues, which originated in the alcohol residue. In a preliminary feeding trial, cattle fed this contaminated DDG in combination with monensin had clinical signs and died with gross and histologic findings comparable to those of the field cases. Even though rations supplemented with the contaminated DDG contained approved levels of monensin, the clinical and postmortem findings were consistent with those expected for monensin toxicosis. The presence of macrolide antibiotic residues in the contaminated feed appeared to affect the biotransformation of otherwise nontoxic levels of monensin, leading to clinical ionophore toxicosis.

Intoxicação por antibióticos ionóforos em animais

“…A concentração de monensina estava dentro dos níveis normais para bovinos (927g/ton) (Basaraba et al 1999). Em frangos, a administração de antibióticos macrolídeos com monensina resulta no decréscimo do consumo de comida e água e, conseqüentemente, no ganho de peso.…”

Intoxicação experimental por monensina em búfalos e bovinos

“…Andriguetto et al 2005). Entretanto, a intoxicação acidental por essa substância tem sido descrita em bovinos (Schweitzer et al 1984, Collins & McCrea 1978, Basaraba et al 1999, ovinos (Nation et al 1982), eqüinos (Ordidge et al 1979), além de várias outras espécies animais (Hulland 1993, Barros 2001, Hall 2004. A intoxicação acidental por monensina resulta freqüentemente de falhas na preparação das dietas, tais como alta dosagem, erro na diluição da ração, erro de identificação de recipientes e uso da substância em espécies não incluídas nas recomendações do produto (Novilla 1992, Barros 2001, Hall 2004.…”

“…Efeitos adversos têm sido observados com aproximadamente 3 mg/ kg em eqüinos, 12 mg/kg em ovinos e mais de 20mg/kg em bovinos (Potter et al 1984, Hulland 1993, Hall 2004. Os sinais clínicos dependem da quantidade de substância tóxica consumida e usualmente incluem anorexia, dispnéia, diarréia, tremores, ataxia, fraqueza muscular, desordens locomotoras, taquicardia, mioglobinúria e morte (Potter et al 1984, Novilla 1992, Basaraba et al 1999. A monensina facilita o transporte iônico através das membranas biológicas por formar complexos lipossolúveis reversíveis com cátions (Pressman 1976, Novilla 1992.…”

“…As características clínicas e patológicas da intoxicação por monensina presentes nos bubalinos desse experimento foram semelhantes às encontradas em relatos anteriores de intoxicação espontânea e experimental por monensina na espécie bovina (Collins & McCrea 1978, Wardrope et al 1983, Potter et al 1984, Schweitzer et al 1984, Geor & Robinson 1985, Galitzer et al 1986, Shlosberg et al 1986, Basaraba et al 1999, Gonzalez et al 2005. Dos 7 bubalinos dosados nesse experimento, 6 desenvolveram sinais clínicos característicos de intoxicação por monensina tais como apatia, anorexia, diarréia, dificuldade de locomoção, dispnéia e morte.…”

The toxicity and adverse effects of selected drugs in animals – overview

“…The attention should be paid also to the combination of these substances with other medicines. It is really dangerous to combine them with tiamulin which is a potent inhibitor of cytochrome P450 3A, enzyme necessary for the metabolism of many ionophores (Szucs et al 2004), or the combination with macrolide antibiotics (Basaraba et al 1999). …”