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Objective--To evaluate local tissue compatibility of doxycycline hyclate (DOX) in antebrachiocarpal joints of calves. Animals--10 healthy calves between 80 and 110 kg. Procedures--Calves were assigned to 2 treatment groups. Calves in groups DOXlow and DOXhigh were administered 5 and 10 mg of DOX, respectively, locally in 1 antebrachocarpal joint. The contralateral joint served as a control joint and was injected with 0.9% NaCl solution. General and local clinical findings were scored. Several variables were assessed in blood and synovial fluid for 9 days. Calves were euthanatized and pathologic changes and drug residues evaluated. Results--Throughout the study, none of the calves had clinical changes or abnormal hematologic values. Significant differences between treatment and control joints were evident only for matrix metalloproteinases at 0.5 hours after injection, with less activity for the DOX-treated joints in both treatment groups. Values for all synovial fluid variables, except nitric oxide, increased significantly during the first 12 to 72 hours after arthrocentesis in control and DOX-treated joints. Histologic examination revealed minimal infiltration of inflammatory cells independent of the treatment. No drug residues were detected 9 days after arthrocentesis in any tissues obtained from the liver, kidneys, fat, and skeletal muscles. Conclusions and Clinical Relevance--DOX had excellent intra-articular compatibility in healthy calves. Arthrocentesis induced a mild transient increase of inflammatory mediators in the synovial fluid. Significant decreases in matrix metalloproteinase activity in DOX-treated joints may indicate a potential chondroprotective effect of DOX. [ABSTRACT FROM AUTHOR]

Objective--To describe the in vitro effects of bethanechol on contractility of smooth muscle preparations from the small intestines of healthy cows and define the muscarinic receptor subtypes involved in mediating contraction. Sample Population--Tissue samples from the duodenum and jejunum collected immediately after slaughter of 40 healthy cows. Procedures--Cumulative concentration-response curves were determined for the muscarinic receptor agonist bethanechol with or without prior incubation with subtype-specific receptor antagonists in an organ bath. Effects of bethanechol and antagonists and the influence of intestinal location on basal tone, maximal amplitude (Amax), and area under the curve (AUC) were evaluated. Results--Bethanechol induced a significant, concentration dependent increase in all preparations and variables. The effect of bethanechol was more pronounced in jejunal than in duodenal samples and in circular than in longitudinal preparations Significant inhibition of the effects of bethanechol was observed after prior incubation with muscarinic receptor subtype M3 antagonists (more commonly for basal tone than for Amax and AUC). The M3 receptor antagonists partly inhibited the response to bethanechol, especially for basal tone. The M3 receptor antagonists were generally more potent than the M, receptor antagonists In a protection experiment, an M3 receptor antagonist was less potent than when used in combination with an M2 receptor antagonist. Receptor antagonists for M1 and M4 did not affect contractility variables. Conclusions and Clinical Relevance--Bethanechol acting on muscarinic receptor subtypes M2 and M3 may be of clinical use as a prokinetic drug for motility disorders of the duodenum and jejunum in dairy cows. [ABSTRACT FROM AUTHOR]

Objective--To describe the distribution of muscarinic receptor subtypes M1 to Ms and interstitial cells of Cajal (ICCs) in the gastrointestinal tract of healthy dairy cows. Sample Population--Full-thickness samples were collected from the fundus, corpus, and pyloric part of the abomasum and from the duodenum, ileum, cecum, proximal loop of the ascending colon, and both external loops of the spiral colon of 5 healthy dairy cows after slaughter. Procedures--Samples were fixed in paraformaldehyde and embedded in paraffin. Muscarinic receptor subtypes and ICCs were identified by immunohistochemical analysis. Results--Staining for M1 receptors was found in the submucosal plexus and myenteric plexus. Antibodies against M2 receptors stained nuclei of smooth muscle cells only. Evidence of M3 receptors was found in the lamina propria, in intramuscular neuronal terminals, on intermuscular nerve fibers, and on myocytes of microvessels. There was no staining for M4 receptors. Staining for M5 receptors was evident in the myocytes of microvessels and in smooth muscle cells. The ICCs were detected in the myenteric plexus and within smooth muscle layers. Distribution among locations of the bovine gastrointestinal tract did not differ for muscarinic receptor subtypes or ICCs. Conclusions and Clinical Relevance--The broad distribution of M1, M3, M5, and ICCs in the bovine gastrointestinal tract indicated that these components are likely to play an important role in the regulation of gastrointestinal tract motility in healthy dairy cows. Muscarinic receptors and ICCs may be implicated in the pathogenesis of motility disorders, such as abomasal displacement and cecal dilatation-dislocation. [ABSTRACT FROM AUTHOR]

Objective--To measure maximum binding capacity (Bmax) and levels of mRNA expression for α2-adrenergic receptor (AR) subtypes in ileal and colonic muscle layers of healthy dairy cows. Sample Population--Ileal and colonic muscle specimens from 6 freshly slaughtered cows. Procedure--Ileal and colonic muscle layers were obtained by scraping the mucosa and submucosa from full-thickness tissue specimens. Level of mRNA expression for α2-AR subtypes was measured by real-time reverse transcriptase-PCR analysis and expressed relative to the mean mRNA expression of glyceraldehyde phosphate dehydrogenase, ubiquitin, and 18S ribosomal RNA. Binding studies were performed with tritiated RX821002 (³H-RX821002) and subtype-selective ligands as competitors, Results--mRNA expression forα2AD-, α2B-, and α2C-AR subtypes was similar in Ileal and colonic muscle layers. The mRNA expression for α2AD-AR was significantly greater than that for α2B- and α2C-AR subtypes, representing 92%, 6%, and 2%, respectively, of the total mRNA Binding competition of ³H RX821002 with BRL44408, imiloxan, and MK-912 was best fitted by a 1-site model. The Bmax of α2AD- and α2C-AR subtypes was greater than that of α2B-AR. The Bmax and level of mRNA expression were only correlated (r = 0.8) for α2AD-AR. Ratio of Bmax to mRNA expression for α2C-AR was similar to that for α2B-AR, but significantly greater than for α2AD-AR, Conclusions and Clinical Relevance--Subtypes of α2-AR in bovine intestinal muscle layers are represented by a mixture of (α2AD- and α2C-ARs and of (α2B-AR at a lower density. Information provided here may help in clarification of the role of AR subtypes in α2-adrenergic mechanisms regulating bovine intestinal motility. [ABSTRACT FROM AUTHOR]

CASE DESCRIPTION neonatal female calves (ages, < I to 4 days) were examined because of mandibular trauma. CLINICALFINDINGS Physical examination indicated that each calf had an open fracture of the mandibular pars incisiva (rostral mandibular fracture) with ventral displacement of the incisors at the affected region. Oral radiographs were obtained for I calf and revealed that 5 incisors were fractured at the level of the apical dental buds. TREATMENT AND OUTCOME Each calf was anesthetized. The fracture site and surrounding tissues were surgically debrided and flushed with sterile 0.05% chlorhexidine solution. The laceration in the oral mucosa was closed with absorbable suture in an interrupted horizontal mattress pattern. Additionally, a Penrose drain was placed during primary closure and removed 4 days later in I calf, The fractured incisors were removed during primary debridement in another calf. All calves received perioperative antimicrobials and analgesics. One calf developed mild osteomyelitis of the rostral mandible, which resolved with additional surgical debridement and antimicrobial treatment. That calf and another developed mild brachygnathia. At the time of last follow-up (3 to 13 months after hospital discharge), all 3 calves were eating and growing as expected. CLINICAL RELEVANCE 3 calves with open rostral mandibular fractures were successfully managed by surgical debridement and primary closure of the oral laceration. The procedure was easy to perform, did not require specialized equipment, and was less expensive than other repair methods. This procedure may be an effective and economic on-farm treatment alternative for calves with rostral mandibular fractures. [ABSTRACT FROM AUTHOR]

Objective--To analyze myoelectric activity of the ileum, cecum, proximal loop of the ascending colon (PLAC), and spiral colon in cows with naturally occurring cecal dilatation-dislocation (CDD) and compare findings with those in healthy cows. Animals--8 CDD-affected and 6 healthy control cows. Procedures--Immediately after diagnosis, CDD-affected cows underwent surgery; control cows underwent a similar surgical procedure. Before completion of surgery, 8 bipolar silver electrodes were implanted in the ileum (n = 2), cecum (1), PLAC (1), and spiral colon (4) of each cow. Beginning the day after surgery, intestinal myoelectric activity was recorded daily (8-hour period) for 4 days; data were analyzed by use of specialized software programs. Quantitative variables of myoelectric activity were compared between groups. Results--Cows of both groups recovered without complications after surgery. In control cows, physiologic myoelectric activity was recorded in all intestinal segments on all days after surgery. Apparently normal myoelectric activity was evident in the ileum of CDD-affected cows on the first day after surgery, but myoelectric activity patterns in the cecum, PLAC, and spiral colon were variable with no organized cyclic myoelectric patterns, incomplete or normally organized migrating myoelectric complexes, and slow normalization over time. Conclusions and Clinical Relevance--After surgery for CDD, normal myoelectric patterns were disrupted in the large intestine of cows, especially in the spiral colon. Clinical recovery with effective transit of ingesta occurred before normalization of myoelectric activity in the large intestine. Therapeutic protocols for restoration or normalization of spiral colon motility should be developed for treatment of CDD-affected cattle. (Am J Vet Res 2010;71:304-313) [ABSTRACT FROM AUTHOR]

Objective--To investigate the distribution of mRNA coding for 9 adrenoceptor subtypes in the intestines of healthy dairy cows and cows with cecal dilatation-dislocation (CDD). Sample Population--Full-thickness specimens of the intestinal wall were obtained from the ileum, cecum, proximal loop of the ascending colon (PLAC), and external loop of the spiral colon (ELSC) of 15 cows with CDD (group 1) and 15 healthy (control) cows (group 2, specimens collected during laparotomy; group 3, specimens collected after slaughter). Procedures--Concentrations of mRNA for 9 adrenoceptor subtypes (α1A, α1B, α1D, α2AD, α2B, α2C, β1, β2, and β3), were measured by quantitative real time reverse transcriptase-PCR assay Results were expressed relative to mRNA expression of a housekeeping gene. Results--Expression of mRNA for (α1B-, α2AD-, α2B-, β1-, and β2-adrenoceptors was significantly lower in cows with CDD than in control cows. In the ileum, these receptors all had lower mRNA expression in cows with CDD than in control cows. The same effect was detected in the ELSC for mRNA for (α2AD-, α2B-, β1-, and β2-adrenoceptors, and in the cecum and PLAC for (α2B- and β2-adrenoceptors. Groups did not differ significantly for α1A-adrenoceptors. The mRNA expression for α1D-, α2C-, and β3-adrenoceptors was extremely low in all groups. Conclusions and Clinical Relevance--Differences in expression of mRNA coding for adrenoceptors, most pronounced in the ileum and spiral colon, between cows with CDD and control cows support the hypothesis of an implication of adrenergic mechanisms in the pathogenesis of CDD in dairy cows. [ABSTRACT FROM AUTHOR]

Objective--To investigate the distribution of mRNA coding for 7 subtypes of 5-hydroxytryptamine receptors (5-HTRs) in the intestines of healthy dairy cows and dairy cows with cecal dilatation-dislocation (CDD). Sample Population--Full-thickness intestinal wall biopsy specimens were obtained from the ileum, cecum, proximal loop of the ascending colon, and external loop of the spiral colon (ELSC) of 15 cows with CDD (group 1) and 15 healthy dairy cows allocated to 2 control groups (specimens collected during routine laparotomy [group 2] or after cows were slaughtered [group 3]). Procedure--Amounts of mRNA coding for 7 subtypes of 5-HTRs (5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, and 5-HT4) were measured by quantitative real-time reverse transcriptase-PCR assay. Results were expressed as the percentage of mRNA expression of a housekeeping gene. Results--Expression of mRNA coding for 5-HTR1B, 5-HTR2B, and 5-HTR4 was significantly lower in cows with CDD than in healthy cows. For 5-HTR2B and 5-HTR4, significant differences between cows with CDD and control cows were most pronounced for the ELSC. Expression of mRNA for 5-HTR1D, 5-HTR1F, and 5-HTR2A was extremely low in all groups, and mRNA for 5-HTR1A was not detected. Conclusions and Clinical Relevance--Relative concentrations of mRNA coding for 5-HTR1B, 5-HT2B, and 5-HTR4 were significantly lower in the intestines of cows with CDD than in the intestines of healthy dairy cows, especially for 5-HT2B and 5-HTR4 in the ELSC. This supports the hypothesis that serotonergic mechanisms, primarily in the spiral colon, are implicated in the pathogenesis of CDD. [ABSTRACT FROM AUTHOR]

Objective--To describe the distribution of mRNA that codes for 9 subtypes of adrenergic receptors in the digestive tract of dairy cows. Sample Population--Fresh full-thickness wall specimens from the abomasum (fundus, corpus, and antrum), ileum, cecum, proximal loop of ascending colon, and 4 locations of the spiral colon collected from 10 healthy cows at slaughter. Procedure--Concentrations of mRNA that code for 9 subtypes of adrenergic receptors in the bovine gastrointestinal tract (α1A, α1B, α1D α2AD, α2B, α2C, β1, β2 and β3) were measured by use of a quantitative real-time reverse transcription-polymerase chain reaction assay. Results were reported in relation to mRNA expression of the housekeeping gene glyceraldehyde phosphate dehydrogenase (GAPDH). Results--Mean mRNA contents of adrenergic receptors in the bovine digestive tract were low (range, 0.00006% to 5.04% of GAPDH). Distribution of receptor subtypes was similar in all tissues, with lowest expression of α1D receptors, followed by α2B, α2C, β3, α1B, α1A, β1 and β2 in the abomasum, whereas α2AD and β2 in the intestines were highest. In comparison with the intestines, relative concentrations of mRNA for receptors β2 and β3 were significantly lower in the abomasum. Conclusions and Clinical Relevance--Relative concentrations of mRNA that code for adrenergic receptors differed among receptor subtypes and among locations in the bovine gastrointestinal tract. Comparison of these values established in healthy cattle with results for cows with motility disorders, such as abomasal displacement and cecal dilatation, may lead to improved... [ABSTRACT FROM AUTHOR]

Objective--To describe the distribution of mRNA that codes for 8 subtypes of 5-hydroxytryptamine receptors (5-HTRs) in the digestive tract of dairy cows. Sample Population--Fresh full-thickness wall specimens from the abomasum (fundus, corpus, and antrum), ileum, cecum, proximal loop of ascending colon, and 4 locations of the spiral colon collected from 10 healthy cows at slaughter. Procedure--Concentrations of mRNA that code for 5-HTR subtypes (5-HTR1A, 5-HTR1B, 5-HTR1D, 5-HTR1F, 5-HTR2A, 5-HTR2B, 5-HTR2C and 5-HTR4) in the bovine digestive tract were measured by use of a quantitative real-time reverse transcription-polymerase chain reaction assay. Results were reported in relation to mRNA expression of the housekeeping gene glyceraldehyde phosphate dehydrogenase (GAPDH). Results--Mean relative mRNA concentrations for 5HTR were low (range, 0% to 1.32% of GAPDH), and mRNA that codes for 5-HTR1A was not detected. In the abomasum, mRNA expression was highest for 5-HTR1B and 5-HTR2B, followed by subtypes 1F, 2A, 1D, and 4, whereas 5-HTR2C was not detected. In intestinal samples, concentrations of subtypes 1B, 2B, and 4 were highest, followed by 1D, 1F, 2A, and 2C. Relative concentrations of mRNA that code for 5-HTR2A were significantly higher in the abomasum than the intestines, but lower for 5-HTR2B, 5-HTR2C and 5-HTR4. Conclusions and Clinical Relevance--Relative concentrations of mRNA that code for 5-HTRs differ among locations in the gastrointestinal tract of cattle. Understanding differences in the distribution of 5-HTRs in healthy cattle and cattle with gastrointestinal tract disease may lead to improved therapeutic approaches for abomasal and cecal motility disorders. [ABSTRACT FROM AUTHOR]

Objective--To describe myoelectric patterns in the intestines of cows after electrode implantation. Animals--7 lactating Simmental-Red Holstein cows. Procedure--Cows were implanted with 7 pairs of bipolar silver electrodes (1 each in the ileum, cecum, and proximal loop of the ascending colon (PLAC) and 4 in the spiral colon). Myoelectric activity was monitored during 10 periods within the first 3 weeks after surgery. Recordings from the first 2 weeks were compared with recordings from the third week, which was considered a steady-state condition. Results--Significant changes over time were detected for 18 of 57 variables, including 3 variables describing myoelectric activity of the ileum, 6 variables of the cecum, 6 variables of the PLAC, and 3 variables of the spiral colon. Compared with values for the steady-state condition, 16 variables differed significantly for the 14-day period after surgery (7 variables until day 11, 2 variables until day 8, 4 variables until day 5, 1 variable until day 3, and 2 variables until day 2 after electrode implantation). None of the variables had significant changes that lasted only 1 day after surgery. Conclusions and Clinical Relevance--Significant changes were observed for several variables of myoelectric activity in all intestinal segments until as late as 11 days after electrode implantation, whereas a steady-state condition was reached 14 days after surgery. Effects of drugs, manipulations, or nutrition regimens on myoelectric activity of the bovine digestive tract should be evaluated no sooner than 2 weeks after electrode implantation. [ABSTRACT FROM AUTHOR]

Objective: To measure maximum binding capacity (B(max)) and levels of mRNA expression for alpha(2)-adrenergic receptor (AR) subtypes in ileal and colonic muscle layers of healthy dairy cows., Sample Population: Ileal and colonic muscle specimens from 6 freshly slaughtered cows., Procedures: Ileal and colonic muscle layers were obtained by scraping the mucosa and submucosa from full-thickness tissue specimens. Level of mRNA expression for alpha(2)-AR subtypes was measured by real-time reverse transcriptase-PCR analysis and expressed relative to the mean mRNA expression of glyceraldehyde phosphate dehydrogenase, ubiquitin, and 18S ribosomal RNA. Binding studies were performed with tritiated RX821002 ((3)H-RX821002) and subtype-selective ligands as competitors., Results: mRNA expression for alpha(2AD)-, alpha(2B)-, and alpha(2C)-AR subtypes was similar in ileal and colonic muscle layers. The mRNA expression for alpha(2AD)-AR was significantly greater than that for alpha(2B)- and alpha(2C)-AR subtypes, representing 92%, 6%, and 2%, respectively, of the total mRNA. Binding competition of (3)H-RX821002 with BRL44408, imiloxan, and MK-912 was best fitted by a 1-site model. The B(max) of alpha(2AD)- and alpha(2C)-AR sub-types was greater than that of alpha(2B)-AR. The B(max) and level of mRNA expression were only correlated (r = 0.8) for alpha(2AD)-AR. Ratio of B(max) to mRNA expression for alpha(2C)-AR was similar to that for alpha(2B)-AR, but significantly greater than for alpha(2AD)-AR., Conclusions and Clinical Relevance: Subtypes of alpha(2)-AR in bovine intestinal muscle layers are represented by a mixture of alpha(2AD)- and alpha(2C)-ARs and of alpha(2B)-AR at a lower density. Information provided here may help in clarification of the role of AR subtypes in alpha(2)-adrenergic mechanisms regulating bovine intestinal motility.

Objective: To characterize and compare in vitro contractility patterns of sections of abomasal wall harvested from cattle of 3 dairy breeds., Sample Population: Longitudinal and circular smooth muscle preparations harvested from the antrum and body of the abomasum of 30 recently slaughtered Holstein-Friesian, Brown Swiss, and Simmental X Red Holstein cows., Procedure: Spontaneous isometric contractions of specimens in tissue baths of modified Krebs solution were recorded during a 4-hour period. Maximal amplitude, frequency of contractions, and change of basal tension were used to characterize contractility. Statistical analyses were used to test for differences among time periods, among breeds, between specimen locations, and between fiber orientations., Results: Myoactivity patterns of abomasal smooth muscle preparations are highly variable and differ on the basis of location and fiber orientation. Frequency of contractions differed significantly among time periods for longitudinally oriented specimens with decreasing frequencies of contractions over time. Maximal amplitude of the longitudinally oriented specimens from the antrum increased significantly, whereas maximal amplitude of the circularly oriented specimens from the antrum decreased significantly. Values did not differ significantly among breeds., Conclusions and Clinical Relevance: Patterns of spontaneous contractility of abomasal wall specimens are not homogeneous. During a 4-hour recording period, maximal amplitude and frequency of contractions of specimens varied significantly with respect to orientation and location; however, spontaneous contractile myoactivity did not differ significantly among breeds. Therefore, breed predisposition for displaced abomasum is not correlated with spontaneous activity of smooth muscle specimens.

Objectives: To describe the effects of an abrupt increase of concentrates in the diet of dairy cows on myoelectric activity of the spiral colon and on fermentation patterns in the rumen and large intestine., Animals: 6 healthy lactating Simmental x Red-Holstein cows., Procedures: The diet of 6 cows implanted with bipolar electrodes in the spiral colon was changed from hay only to a ration of 50% hay:50% starch-rich concentrates during a period of 60 hours. Myoelectric activity of the spiral colon, concentrations of absolute and undissociated volatile fatty acids (VFA), and pH of ruminal and large intestinal contents were monitored before, during, and after the dietary change., Results: Significant changes in patterns of myoelectric activity of the spiral colon were restricted to phases III and IV of the bovine migrating myoelectric complex and to propagation velocity. Significant alterations were not observed in pH or VFA concentrations in ruminal fluid, but pH decreased and VFA concentrations increased significantly in fecal specimens after the change of diet., Conclusions and Clinical Relevance: Although rumen fluid is of limited value for measurement of certain indicators of fermentation, fecal samples can be used for measurement of pH and VFA concentrations, which serve as indicators of fermentation patterns in the large intestine. Increased concentrations of VFA and low pH in large intestinal digesta have a minimal influence on myoelectric activity of the spiral colon. Increased luminal VFA concentrations are unlikely to play an important role in the etiopathogenesis of motility disorders of the large intestine in cattle.

Objective: To describe myoelectric activity of the spiral colon in healthy cows., Animals: 7 lactating Simmental X Red-Holstein crossbred cows., Procedure: Cows were implanted with 7 pairs of bipolar silver electrodes (4 in the spiral colon and 1 each in the cecum, distal part of the ileum, and proximal loop of the ascending colon [PLAC]). Myo-electric activity was recorded during 4 days for each cow. Patterns were analyzed, using computer-based methods., Results: Myoelectric activity of the spiral colon was closely associated with motility of the ileum and PLAC and showed the typical organization of migrating myoelectric complexes (MMC). The MMC in the bovine spiral colon (bcMMC) had a mean +/- SD duration of 188.6 +/- 30.8 minutes and was divided into 4 phases. Phases I and II lasted 11.3 +/- 1.4 and 159.4 +/- 33.3 minutes, respectively. Phase III (duration, 5.4 +/- 1.2 minutes) was characterized by 5.2 +/- 0.9 regular spindles (35.4 +/- 5.4 seconds) and 1 final elongated spindle (137.2 +/- 56.4 seconds). Phase III most commonly (73.8 +/- 16.1%) was followed by phase IV (duration, 173 +/- 3.6 minutes). Propagation velocity of phase III was 4.4 +/- 0.5 cm/min, and 13.6% of bcMMC were incompletely propagated through the spiral colon., Conclusions: Myoelectric activity of the bovine spiral colon is composed of a recurring cyclic pattern similar to MMC of the small intestine. Data of colonic myoelectric activity in healthy cows will serve as a basis for studies on cecal dilatation and dislocation in cattle.