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Abstract
Monensin is an ionophore antibiotic well known for its multiple benefits in cattle diets. Toxic monensin Lethal Dose 50 (LD50 ) concentrations in cattle are reported from 26 mg/kg BW. Intraruminal monensin boluses consist of controlled-released capsules, often administered to beef or dairy cattle. Seven outbreaks were analyzed, all occurring in Buenos Aires province between 1997 and 2024 affecting steers in extensive or semi-extensive grazing systems. Clinical signs appeared one to five months after boluses application and included loss of appetite, decay, recumbency, reluctance to move, tachypnea, isolation, muscle tremors, ear drooping and sudden death. Twelve necropsies were performed, and gross findings included pale multifocal streaks myocardium of both ventricles, edema in cavities and mesenteries, hepatomegaly, and diffusely non collapsed or inflated lung with interlobular edema. Microscopically, the most characteristic lesion present in all 12 necropsies was necrotizing cardiomyopathy in different stages of regeneration, some of them being polyphasic. Masson trichrome stain revealed fibrous connective tissue in extensive multiple areas replacing cardiac muscle cells. Mean serum CPK was considered moderately to highly elevated. Herein in all 7 outbreaks, boluses apparently failed to release pills correctly. In conclusion, though toxicosis after failure of intraruminal boluses in grazing cattle are rare, it is important to describe the occurrence of cases when release bolus mechanism fails, causing intoxication that evolves from subacute to chronic, with characteristic pathological findings of polyphasic muscle lesions.
References
Anjos, M. C., Campos, L. C., Depes, V. C. A., Faccin, T. C., Pereira, P. F. V., Bracarense, A. P., Flaiban, K. K., & Lisbôa, J. A. N. (2023). Accidental monensin poisoning in goats. Toxicon: Official Journal of the International Society on Toxinology, 235, 107314. https://doi.org/10.1016/j.toxicon.2023.107314. PMid:37857004.
Basaraba, R. J., Oehme, F. W., Vorhies, M. W., & Stokka, G. L. (1999). Toxicosis in cattle from concurrent feeding of monensin and dried distiller’s grains contaminated with macrolide antibiotics. Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 11(1), 79-86. https://doi.org/10.1177/104063879901100113. PMid:9925217.
Bence, A. R., García, J., Fernández, E., Morrell, E. L., & Cantón, G. J. (2018). Hallazgos clínico-patológicos compatibles con intoxicación con ionóforos en búfalas: Primer reporte en Argentina. Revista Veterinaria, 29(2), 79-82. https://doi.org/10.30972/vet.2923268.
Brito, E. S. A., Andrade, T. G., Oliveira, C. H. S. D., & Moura, V. M. D. D. (2020). Outbreak of monensin poisoning in cattle due to supplementation error. Ciência Rural, 50(11), e20190996. https://doi.org/10.1590/0103-8478cr20190996.
Callaway, T. R., Edrington, T. S., Rychlik, J. L., Genovese, K. J., Poole, T. L., Jung, Y. S., Bischoff, K. M., Anderson, R. C., & Nisbet, D. J. (2003). Ionophores: Their use as ruminant growth promotants and impact on food safety. Current Issues in Intestinal Microbiology, 4(2), 43-51. PMid:14503688.
Condon, F. P., & McKenzie, R. A. (2002). Fatal monensin toxicity in a dog after chewing a bovine intra-ruminal slow-release device. Australian Veterinary Practitioner, 32(4), 179-180.
Cooper, B. J., & Valentine, B. A. (2016). Muscle and tendon. In G. Maxie (Ed.), Jubb, Kennedy and Palmer’s Pathology of Domestic Animals (6th ed., Vol. 1, pp. 164-219). Elsevier. https://doi.org/10.1016/B978-0-7020-5317-7.00003-5.
Duffield, T. F., Leslie, K. E., Sandals, D., Lissemore, K., McBride, B. W., Lumsden, J. H., Dick, P., & Bagg, R. (1999). Effect of a monensin-controlled release capsule on cow health and reproductive performance. Journal of Dairy Science, 82(11), 2377-2384. https://doi.org/10.3168/jds.S0022-0302(99)75488-3. PMid:10575604.
Elanco. (2020). RumensinTM Bolos ABC. https://assets-us-01.kc-usercontent.com/e4748d51-2c24-00f7-fc54 65f3864ee8b1/6e791557-65f3-4448-ab97-3b00cdea249e/Rumensin_Bolos_ABC_-_Label.pdf
Ensley, S. (2020). Ionophore use and toxicosis in cattle. The Veterinary Clinics of North America. Food Animal Practice, 36(3), 641-652. https://doi.org/10.1016/j.cvfa.2020.07.001. PMid:32948411
Gabor, L. J., & Downing, G. M. (2003). Monensin toxicity in preruminant dairy heifers. Australian Veterinary Journal, 81(8), 476-478. https://doi.org/10.1111/j.1751-0813.2003.tb13364.x. PMid:15086082.
Gonzalez, M., Barkema, H. W., & Keefe, G. P. (2005). Monensin toxicosis in a dairy herd. The Canadian Veterinary Journal = La Revue Vétérinaire Canadienne, 46(10), 910-912. PMid:16454383.
Grainger, C., Auldist, M. J., Clarke, T., Beauchemin, K. A., McGinn, S. M., Hannah, M. C., Eckard, R. J., & Lowe, L. B. (2008). Use of monensin controlled-release capsules to reduce methane emissions and improve milk production of dairy cows offered pasture supplemented with grain. Journal of Dairy Science, 91(3), 1159-1165. https://doi.org/10.3168/jds.2007-0319. PMid:18292272.
Green, B. L., McBride, B. W., Sandals, D., Leslie, K. E., Bagg, R., & Dick, P. (1999). The impact of a monensin controlled-release capsule on subclinical ketosis in the transition dairy cow. Journal of Dairy Science, 82(2), 333-342. https://doi.org/10.3168/jds.S0022-0302(99)75240-9. PMid:10068955.
Hall, J. O. (2004). Ionophores. In Clinical Veterinary Toxicology, ed Konnie Plumlee ed p120-127.Mosby, Elsevier: St. Louis, MO.
Kaneko, J. J., Harvey, J. W., & Bruss, M. L. (2008). Clinical biochemistry of domestic animals. Academic press, Elsevier: Oxford, UK.
Krafsur, G. M., Neary, J. M., Garry, F., Holt, T., Gould, D. H., Mason, G. L., Thomas, M. G., Enns, R. M., Tuder, R. M., Heaton, M. P., Brown, R. D., & Stenmark, K. R. (2019). Cardiopulmonary remodeling in fattened beef cattle: A naturally occurring large animal model of obesity-associated pulmonary hypertension with left heart disease. Pulmonary Circulation, 9(1), 2045894018796804. https://doi.org/10.1177/2045894018796804. PMid:30124135.
Moxley, R. A., Smith, D. R., Grotelueschen, D. M., Edwards, T., & Steffen, D. J. (2019). Investigation of congestive heart failure in beef cattle in a feedyard at a moderate altitude in western Nebraska. Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 31(4), 509-522. https://doi.org/10.1177/1040638719855108. PMid:31170901.
Nogueira, V. A., França, T. N., & Peixoto, P. V. (2009). Intoxicação por antibióticos ionóforos em animais. Pesquisa Veterinária Brasileira, 29(3), 191-197. https://doi.org/10.1590/S0100-736X2009000300001.
Odriozola, E., Lloberas, M. M., & Peralta, M. (1999). Muerte accidental en bovinos por consumo de monensina. In XXVII Jornadas Uruguayas de Buiatría. Jornadas Uruguayas de Buiatría (pp. 45-47). Centro Medico Veterinario de Paysandú.
Romero, A., García, J. A., & Dutra, F. (2018). Intoxicación por monensina en ovinos en Uruguay. Veterinaria (Montevideo), 54(210), 10-14.
Rozza, D. B., Vervuert, I., Kamphues, J., Farias da Cruz, C. E., & Driemeier, D. (2006). Monensin toxicosis in water buffaloes (Bubalus bubalis). Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 18(5), 494-496. https://doi.org/10.1177/1040638706 01800515. PMid:17037623.
Soares, M. P., Pavarini, S. P., de Lourdes Adrien, A., de Souza Quevedo, P., Schild, A. L., Peixoto, P. V., Farias da Cruz, C. E., & Driemeier, D. (2011). Amorimia exotropica poisoning as a presumptive cause of myocardial fibrosis in cattle. Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 23(6), 1226-1229. https://doi.org/10.1177/1040638711425586. PMid:22362807.
Varga, A., & Puschner, B. (2012). Retrospective study of cattle poisonings in California: Recognition, diagnosis, and treatment. Veterinary Medicine (Auckland), 3, 111-127. https://doi.org/10.2147/VMRR.S28770. PMid:30155434.
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