title: Changes in thermal nociceptive responses in dairy cows following experimentally induced Escherichia coli mastitis.
abstract: BACKGROUND
  Mastitis is a high incidence disease in dairy cows. The acute stage is considered painful and inflammation can lead to hyperalgesia and thereby contribute to decreased welfare. The aim of this study was to examine changes in nociceptive responses toward cutaneous nociceptive laser stimulation (NLS) in dairy cows with experimentally induced Escherichia coli mastitis, and correlate behavioral changes in nociceptive responses to clinical and paraclinical variables.
  
  
  METHODS
  Seven Danish Holstein-Friesian cows were kept in tie-stalls, where the E. coli associated mastitis was induced and laser stimulations were conducted. Measurements of rectal temperature, somatic cell counts, white blood cell counts and E. coli counts were conducted. Furthermore, scores were given for anorexia, local udder inflammation and milk appearance to quantify the local and systemic disease response. In order to quantify the nociceptive threshold, behavioral responses toward cutaneous NLS applied to six skin areas at the tarsus/metatarsus and udder hind quarters were registered at evening milking on day 0 (control) and days 1, 2, 3, 6 and 10 after experimental induction of mastitis.
  
  
  RESULTS
  All clinical and paraclinical variables were affected by the induced mastitis. All cows were clinically ill on days 1 and 2. The cows responded behaviorally toward the NLS. For hind leg stimulation, the proportion of cows responding by stepping was higher on day 0 than days 3 and 6, and the frequency of leg movements after laser stimulation tended to decrease on day 1 compared to the other days. After udder stimulation, the proportion of cows responding by stepping was higher on day 1 than on all other days of testing. Significant correlations between the clinical and paraclinical variables of disease and the behavioral responses toward nociceptive stimulation were found.
  
  
  CONCLUSIONS
  Changes in behavioral responses coincide with peaks in local and systemic signs of E. coli mastitis. During the acute stage of E. coli mastitis nociceptive thermal stimulation on hind leg and mammary glands results in decreased behavioral responses toward nociceptive stimulation, which might be interpreted as hypoalgesia.
authors: Trekantens Dyrlæger, Teglværksvej 42, DK-7000 Fredericia, Denmark.
authors: Ditte B
authors: DB
authors: Rasmussen
authors: Katrine
authors: K
authors: Fogsgaard
authors: Christine M
authors: CM
authors: Røntved
authors: Ilka C
authors: IC
authors: Klaas
authors: Mette S
authors: MS
authors: Herskin
references: Physiol Behav. 2004 Dec 15;83(3):411-20
references: 15581663
references: BMC Genomics. 2011 Feb 28;12:130
references: 21352611
references: J Anim Sci. 1999 Nov;77(11):2918-24
references: 10568459
references: Vet Microbiol. 2009 Feb 16;134(1-2):82-8
references: 18930610
references: J Dairy Sci. 2009 Mar;92(3):922-34
references: 19233785
references: Vet Res. 2003 Sep-Oct;34(5):521-64
references: 14556694
references: BMC Genomics. 2010 Feb 25;11:138
references: 20184744
references: Appl Anim Behav Sci. 2000 Mar 1;66(4):289-304
references: 10700628
references: Neurosci Biobehav Rev. 1988 Summer;12(2):123-37
references: 3050629
references: J Anim Sci. 2003 Apr;81(4):945-54
references: 12723084
references: J Dairy Sci. 2006 Jun;89(6):1877-95
references: 16702252
references: Life Sci. 1999;64(18):1675-87
references: 10328527
references: Reprod Domest Anim. 2008 Jul;43 Suppl 2:252-9
references: 18638132
references: Vet Rec. 2008 Aug 9;163(6):175-9
references: 18689778
references: Acta Vet Scand. 1999;40(1):35-46
references: 10418194