Population Medicine & Diagnostic Sciences


Advancing the health and well-being of animals and people


Advancing the health and well-being of animals and people


Advancing the health and well-being of animals and people


Advancing the health and well-being of animals and people


Advancing the health and well-being of animals and people


Advancing the health and well-being of animals and people

Lorin D. Warnick


Professor of Ambulatory and Production Medicine
Dept. of Population Medicine and Diagnostic Sciences
College of Veterinary Medicine
Cornell University
Ithaca, New York 14853
Tel: (607) 253-3030
Fax: (607) 253-3056


Research Interests

My current research is focused on the epidemiology of Salmonella infections and antimicrobial resistance of enteric bacteria in dairy cattle. I teach bovine medicine, herd health and population medicine in pre-clinical courses. I also serve as Associate Dean for Veterinary Education and Director of the Cornell University Hospital for Animals in the College of Veterinary Medicine.



  • B.S. - 1984        Microbiology, University Honors and Cum Laude; Brigham Young University, Provo, Utah.
  • DVM - 1988    With High Distinction; Colorado State University, Fort Collins, Colorado.
  • Ph.D. - 1994     Cornell University, Ithaca, New York. Major Field: Veterinary Medicine (Epidemiology Concentration), Minor Field: Statistics.

Certifications and Licenses

  • Diplomate in the American College of Veterinary Preventive Medicine, July 1995


Research and Professional Experience

  • 1995 - 1996 Statistical and Experimental Design Service Laboratory Faculty Coordinator; Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, Virginia.
  • 1994- 1996 Assistant Professor of Large Animal Clinical Sciences; Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, Virginia.
  • 1997- 1999 Ambulatory and Production Medicine Section Chief; College of Veterinary Medicine, Cornell University, Ithaca, New York.
  • 1996 - 2002 Assistant Professor of Ambulatory and Production Medicine; Cornell University College of Veterinary Medicine, , (joint appointment in the Section of Epidemiology).
  • 2002 - 2008 Associate Professor of Ambulatory and Production Medicine; Cornell University College of Veterinary Medicine .
  • 2008 - present Professor of Ambulatory and Production Medicine: Cornell University College of Veterinary Medicine .

Honors and Awards

  • Phi Zeta Veterinary Honor Society, 1987.
  • Phi Kappa Phi Honor Society, 1988.
  • Graduate Research Assistantship, 1991-1993; Dept. of Clinical Sciences, New York State College of Veterinary Medicine, Ithaca, New York.


Professional Society Memberships

  • American Veterinary Medical Association
  • American Association of Bovine Practitioners
  • American Dairy Science Association

Graduate Field Memberships

  • Comparative Biomedical Sciences
  • Food Science and Technology
  • Epidemiology (Minor Field)


Selected Publications

Bicalho RC, Cheong SH, Warnick LD, Guard CL. Evaluation of progesterone supplementation in a prostaglandin F2α-based presynchronization protocol before timed insemination. Journal of Dairy Science 90:1193-1200;2007.

Ray KA, Warnick LD, Mitchell R, Kaneene JB, Ruegg PL, Wells SJ, Fossler CP, Halbert LW, May K. Salmonella Antimicrobial Resistance on Midwest and Northeast US Dairy Farms. Preventive Veterinary Medicine 79:204-223;2007.

Alcaine, SD, Warnick LD, Wiedmann M. Antimicrobial Resistance in Salmonella: A Review. Journal of Food Protection 70:780-790;2007.
Bicalho RC, Galvão KN, Cheong SH, Gilbert RO, Warnick LD, and Guard CL. Effect of stillbirths on dam's survival and reproduction performance in Holstein dairy cows. Journal of Dairy Science 90:2797-2803;2007.

Nielsen LR, Warnick LD, Greiner M. Risk factors for changing test classification in the Danish surveillance program for Salmonella in dairy herds. Journal of Dairy Science 90:2815-2825;2007.


Cho S, Fossler CP, Diez-Gonzalez F, Wells SJ, Hedberg CW, Kaneene JB, Ruegg PL, Warnick LD, Bender JB. Antimicrobial susceptibility of shiga toxin producing Escherichia coli isolated from organic and conventional dairy cattle farms and county fairs in Minnesota. Foodborne Pathogens and Disease 4:178-186;2007.

Davis MA, Besser TE, Eckmann K, MacDonald K, Green D, Hancock DD, Baker KNK, Warnick LD, Wiedmann M, Soyer Y, Call DR. Emerging multi-drug resistant strain of Salmonella enterica serovar Typhimurium in the Pacific Northwest United States. Emerging Infectious Disease 13:1583-1586;2007.

Bicalho RC, Cheong SH, Galvão KN, Warnick LD, and Guard CL. The detrimental effects of twin parturition in Holstein cows are increased by the presence of at least one dead twin at birth. Journal of the American Veterinary Medical Association 231:1390-1397;2007.

Morello SL, Ducharme NG, Hackett RP, Warnick LD, Mitchell LM, Soderholm LV. Activity of selected rostral and caudal hyoid muscles in normal horses during strenuous exercise. American Journal of Veterinary Research 69:682-689;2008.

Aubry P, Warnick LD, DesCôteaux L,Bouchard E. Uterine torsions in cattle : 55 field cases. Canadian Veterinary Journal 49:366-372;2008.
Bicalho RC, Warnick LD, Guard CL. Strategies to analyze milk losses caused by diseases with potential occurrence throughout lactation: A lameness example. Journal of Dairy Science 91:2653-2661;2008.

Bicalho RC, Galvão KN, Warnick LD, Guard CL. Stillbirth parturition reduces milk production in Holstein cows. Preventive Veterinary Medicine 84:112-120;2008.

Kaneene JB, Warnick LD,Bolin CA, Erskine RJ, May K, Miller R. Changes in tetracycline susceptibility in enteric bacteria following switching to non-medicated milk replacer in dairy calves. Journal of Clinical Microbiology 46:1968-1977;2008.

Jordan D. Nielsen LR, Warnick LD. Modelling a national program for the control of food-borne pathogens in livestock: the case of Salmonella Dublin in the Danish cattle industry. Epidemiology and Infection 4:1-16;2008 (Epub ahead of print).

Lanzas C, Brien S, Ivanek R, Lo P, Chapagain P, Ray KA, Ayscue P, Warnick LD and Gröhn YT. The effect of heterogeneous infectious period and contagiousness on the dynamics of Salmonella transmission. Epidemiology and Infection Jan. 16:1-15;2008 (Epub ahead of print).

Lanzas, C, Warnick, LD, Ivanek, R., Ayscue, P, Nydam, DV, Grohn, YT, 2008. The risk and control of Salmonella outbreaks in dairy calves. Submitted to Veterinary Research 39:61;2008.

Alexander (Ray) K, Warnick LD, Wiedmann M. Antimicrobial resistant Salmonella in dairy cattle in the United States. Veterinary Research Communications 33:191-2092009.

Moreno Switt, AI, Soyer Y, Warnick LD, Wiedmann M. Emergence, distribution and molecular and phenotypic characteristics of Salmonella enterica serotype 4,5,12:i:-. Foodborne Pathogens and Disease 6:407-4152009.

Davis MA, Baker, KNK, Call DR, Warnick LD, Soyer Y, Wiedmann M, Gröhn Y, McDonough PL, Hancock DD, Besser TE. 2009. Multiple locus variable number of tandem repeats typing method for Salmonella enterica serovar Newport. J Clin Microbiol. 47:1934-19382009.

Cummings KJ, Divers TJ, McDonough PL, Warnick LD. Salmonella among cattle admitted to a veterinary medical teaching hospital 1996-2007. Journal of the American Veterinary Medical Association 234:1578-15852009.

Cho S, Fossler CP, Diez-Gonzalez F, Wells SJ, Hedberg CW, Kaneene JB, Ruegg PL, Warnick LD, Bender JB. Animal-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria (STB) on organic and conventional dairy farms in Minnesota. Can J Vet Res 73:151-1562009.

Cummings KJ, Warnick LD, Cripps C, Grohn YT, McDonough PL, Nydam DV, Alexander KA, Reed KE. Incidence of Salmonellosis among Dairy Herds in the Northeastern United States. Journal of Dairy Science 92:3766-37742009.

Breed MW, Guard CL, White ME, Smith MC, Warnick LD. Pregnancy diagnosis by a commercial ELISA versus palpation. Journal of the American Veterinary Medical Association 235:292-2982009.

Alexander (Ray) KA, Warnick LD, Cripps CJ, McDonough PL, Grohn YT, Wiedmann M, Reed KE, James KL, Soyer Y, Ivanek R. Fecal shedding, antimicrobial resistance, and serological response to Salmonella Typhimurium in calves on two dairy herds in the Northeast U.S. Journal of the American Veterinary Medical Association 235:739-7482009.

Cho S, Whittam T, Boxrud D, Bartkus J, Rankin S, Wilkins M, Somsel P, Downes F, Musser K, Root T, Warnick L, Weidmann M, Saeed, M. Use of multiple-Locus VNTR Analysis and Phage Typing for Subtyping Salmonella Enteritidis from Sporadic Human Cases In the United States. Journal of Applied Microbiology 108:859-8672009.

Cummings KJ, Warnick LD, Grohn YT, McDonough PL, Ray KA, Cripps CJ, Reed KE, James KL. The Duration of Fecal Salmonella Shedding among Dairy Cattle Following Clinical Disease. Preventive Veterinary Medicine 92:134-1392009.

Soyer Y, Moreno Switt, A, Davis MA, Maurer J, McDonough PL, Schoonmaker-Bopp DJ, Dumas NB, Root T, Warnick LD, Gröhn YT and Wiedmann M. 2009. Salmonella 4,5,12:i:-: an emerging Salmonella serotype that represents multiple distinct clones. J. Clin. Microbiol. 47:3546-3556 2009.

Kaneene JB, Warnick LD, Bolin CA, Erskine RJ, May k, Miller R. Changes in multidrug resistance of enteric bacteria following an intervention to reduce antimicrobial resistance in dairy calves. J Clin Microbiol 47:4109-41122009.

Cummings KJ, Divers TJ, McDonough PL, Wiedmann M, Moreno Swittt A, Warnick LD. Temporal clusters of bovine Salmonella cases at a veterinary medical teaching hospital, 1996-2007l Vector-Borne and Zoonotic Diseases 5:471-4792010.

Lanzas C, Warnick LD, James KL, Wright EM, Wiedmann M, and Grohn YT. Transmission dynamics of a multi-drug resistant Salmonella Typhimurium outbreak in a dairy farm. Foodborne Pathogens and Disease 7:467-4742010.

Soyer Y, Alcaine SD, Schoonmaker-Bopp DJ, Root TP, Warnick LD, McDonough PL, Dumas NB, Gröhn YT, Wiedmann M. Pulsed-field gel electrophoresis diversity of human and bovine clinical Salmonella isolates. Foodborne Pathogens and Disease 7:707-7172010.

Cummings KJ, Warnick LD, Elton M, Rodriguez-Rivera LD, Siler JD, Wright EM, Gröhn YT, Wiedmann M. Salmonella enterica serotype Cerro among dairy cattle in New York: an emerging pathogen? Foodborne Pathogens and Disease 7:659-6652010.

Cummings KJ, Warnick LD, Elton M, Gröhn YT, McDonough PL, Siler JD. The effect of clinical outbreaks of salmonellosis on the prevalence of fecal Salmonella shedding among dairy cattle in New York. Foodborne Pathogens and Disease 7:815-8232010.

Leone WM, Nydam DV, Welcome F, Warnick LD, Effects of removing cows from chronic oxytocin use during lactation. The Bovine Practitioner Spring:83-872010.

Hoelzer, K, Soyer, Y, Rodriguez-Rivera, LD, Cummings, KJ, McDonough PL, Schoonmaker-Bopp DJ, Root TP, Dumas NB, Warnick LD, Gröhn YT, Wiedmann M , Baker KNK, Besser TE, Hancock DD, and Davis MA. Prevalence of multidrug resistance is higher among bovine than human Salmonella Newport, Typhimurium and 4,5,12:i:- isolates, but differs by serotype and geographic region in the US. Applied and Environmental Microbiology 76: 5947-59592010.

Scaria J, Warnick LD, Kaneene JB, May K, Teng CH and Chang YF. Comparison of phenotypic and genotypic antimicrobial profiles in Eschericia coli and Salmonella enterica from the same dairy cattle farms. Molecular and Cellular Probes 24:325-345 2010.

Hurd HS, Vaughn MB, Holtkamp D, Dickson J, Warnick L, Quantitative risk from fluoroquinolone-resistant Salmonella and Campylobacter due to treatment of dairy heifers with enrofloxacin for bovine respiratory disease. Foodborne Pathogens and Disease 11:1305-13222010.

Mann S, Siler JD, Jordan D, Warnick LD. Antimicrobial susceptibility of fecal Escherichia coli isolates in dairy cows following systemic treatment with ceftiofur or penicillin. Foodborne Pathogens and Disease 8:861-867;2011.

Hoelzer K, Cummings KJ, Wright EM, Rodriguez-Rivera LD, Roof SE, Moreno Switt AI, Dumans NB, Root TP, Schoonmaker-Bopp DJ, Grohn YT, Siler JD, Warnick LD, Hancock DD, Davis MA, Wiedmann M. Salmonella Cerro isolated over the past twenty years from various sources in the US represent a single predominant pulsed-field gel electrophoresis type. Veterinary Microbiology 150:389-393;2011.

Hoelzer K, Cummings KJ, Warnick LD, Schukken YH, Siler JD, Gröhn YT, Davis MA, Besser, TE, and Wiedmann M. Agar disk diffusion and automated microbroth dilution produce similar antimicrobial susceptibility testing results for Salmonella serotypes Newport, Typhimurium and 4,5,12:i- but differ in economic cost. Foodborne Pathogens and Disease 8:1281-1288;2011.

Cummings KJ, Warnick LD, Gröhn YT, Hoelzer K, Root TP, Siler JD, McGuire SM, Wright EM, Zansky SM, Wiedmann M. Clinical features of human salmonellosis caused by bovine-associated subtypes in New York. Foodborne Pathogens and Disease 9:796-802;2012.

Cummings KJ, Warnick LD, Davis MA, Eckmann K, Gröhn YT, Hoelzer K, MacDonald K, Root TP, Siler JD, Solghan SM, Wiedmann M, Wright EM, Zansky SM, and Besser TE. Farm animal contact is a risk factor for salmonellosis caused by bovine-associated subtypes. Emerging Infectious Disease 18:1929-1936;2012.

Cummings KJ, Perkins GA, Khatibzadeh SM, Warnick LD, Altier C. Antimicrobial resistance trends among salmonella isolates obtained from dairy cattle in the northeastern United States, 2004-2011. Foodborne Pathogens and Disease. 10:353-361;2013.