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  • Author or Editor: Dawn E. Morin x
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Objective—To determine whether results of antimicrobial susceptibility testing of bacterial pathogens isolated from the milk of dairy cows with clinical mastitis were associated with duration of clinical signs or bacteriologic cure rate following treatment with cephapirin and oxytetracycline.

Design—Observational study on a convenience sample.

Animals—58 dairy cows with 121 episodes of clinical mastitis.

Procedure—Cows that only had abnormal glandular secretions were treated with cephapirin alone. Cows with an inflamed gland and abnormal glandular secretions were treated with oxytetracycline and cephapirin. Cows with systemic signs of illness, an inflamed gland, and abnormal glandular secretions were treated with oxytetracycline and flunixin meglumine and frequent stripping of the affected glands. The Kirby-Bauer method was used for antimicrobial susceptibility testing, and current guidelines were used to categorize causative bacteria as susceptible or resistant to the treatment regimen.

Results—Median durations of episodes of clinical mastitis caused by susceptible (n = 97) and resistant (24) bacteria were not significantly different. Bacteriologic cure rates at 14 and 28 days were similar for episodes caused by susceptible and resistant bacteria; however, for 56 episodes of clinical mastitis caused by gram-positive bacteria and treated with cephapirin alone, bacteriologic cure rate at 28 days was significantly higher for susceptible than for resistant bacteria.

Conclusions and Clinical Relevance—Results suggest that antimicrobial susceptibility testing was of no value in predicting duration of clinical signs or bacteriologic cure rate in dairy cows with mastitis, except for episodes caused by gram-positive organisms treated with intramammary administration of cephapirin alone. (J Am Vet Med Assoc 2002;221:103–108)

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in Journal of the American Veterinary Medical Association


Objective—To determine changes in abomasal position and dimensions during the last 3 months of gestation and first 3 months of lactation via transabdominal ultrasonography and determine whether surgical correction of left-displaced abomasum (LDA) by right flank omentopexy alters abomasal position within the abdomen in Holstein-Friesian cows.

Design—Observational study.

Animals—20 heifers and 20 cows with no history of an LDA and 7 cows that had been treated for LDA via right flank omentopexy during an earlier lactation.

Procedure—Ultrasonographic measurements were obtained 8 times during the last 3 months of gestation and first 3 months of lactation. Abomasal length, width, and volume were calculated from these measurements.

Results—The abomasum was always wider than it was long and located predominantly to the right of the midline. The presence of a right flank omentopexy had no effect on the measured parameters. Abomasal length decreased and width increased during the last 3 months of gestation, resulting in a more transverse orientation of the abomasum within the abdomen. These changes appeared to be in response to cranial expansion of the gravid uterus. The abomasum returned to a more caudal and right sagittal position within 14 days after parturition.

Conclusions and Clinical Relevance—Abomasal dimensions, position, and volume change markedly during the last 3 months of gestation and first 3 months of lactation. Results permit detection of abnormal abomasal position in ill cows and indicate that the preferred location for abomasopexy is 20 cm caudal to the xiphoid process and 5 to 10 cm to the right of the ventral midline. (J Am Vet Med Assoc 2005;227:1469–1475)

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in Journal of the American Veterinary Medical Association


Objective—To determine clinical examination findings, clinicopathologic abnormalities, and outcome of treatment in dairy cattle with abomasal impaction.

Design—Retrospective study.

Animals—80 lactating Holstein-Friesian cows ≥ 2 years old.

Procedure—Medical records of cattle with abomasal impaction admitted between 1980 and 2003 were retrieved, and data were extracted.

Results—All cows were reported to have decreased food intake; concurrent diseases were identified in 54 (68%). Seventeen cows did not have detectable ruminal motility, but physical examination findings were nonspecific and variable. In general, cattle had mild hypocalcemia, hyperbilirubinemia, and hyperglycemia, but serum potassium and chloride concentrations were typically within reference limits. Fifty-five (69%) cattle had impaction of the pyloric antrum alone, and 25 (31%) had impaction of the abomasal body and pyloric antrum. Right flank laparotomy and abomasal massage were performed in 73 cattle. After surgery, 54 (74%) cattle received 3 to 4 L of mineral oil, PO, daily for 1 to 5 days. Short-term (ie, discharged from the hospital) survival rate was significantly higher for cows with impaction of the pyloric antrum alone (42/45 [93%]) than for cows with impaction of the body and antrum (12/24 [50%]).

Conclusions and Clinical Relevance—Results suggest that physical examination findings and results of serum biochemical analyses do not facilitate the diagnosis of abomasal impaction in lactating Holstein cows and that exploratory right flank laparotomy is necessary to make the diagnosis. Abomasal impaction should be considered as a differential diagnosis for inappetence and poor milk production in lactating dairy cows. (J Am Vet Med Assoc 2005;227:287–291)

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in Journal of the American Veterinary Medical Association


Objectives—To compare abomasal emptying rates in calves after suckling milk replacer or 3 common orally administered electrolyte solution components.

Animals—5 male calves < 35 days of age.

Procedures—Calves with a cannula fitted in the abomasal body were fed 2 L of milk replacer with or without parenteral administration of atropine (0.01 mg/kg, IV, then 0.02 mg/ kg, SC, q 30 min) or isotonic (150mM) solutions of sodium acetate, NaHCO3, or NaCl in a randomized crossover design. Abomasal emptying rates were determined via scintigraphy, acetaminophen absorption, ultrasonography, and change in abomasal luminal pH.

Results—Scintigraphic half-emptying time, time of maximal plasma acetaminophen concentration, ultrasonographic half-emptying time, and pH return time indicated similar abomasal emptying rates following suckling of isotonic sodium acetate, NaHCO3, and NaCl solutions, whereas the emptying rate of milk replacer was significantly slower. Mean maximal abomasal luminal pH was highest following suckling of NaHCO3 (pHmax = 7.85) and lowest following suckling of NaCl (pHmax = 4.52); sodium acetate (pHmax = 6.59) and milk replacer (pHmax = 5.84) yielded intermediate pH values.

Conclusions and Clinical Relevance—Isotonic solutions of sodium acetate, NaHCO3, and NaCl were rapidly emptied from the abomasum but varied markedly in their ability to alkalinize the abomasum. Sodium bicarbonate–containing orally administered electrolyte solution might increase the frequency of infection or severity of clinical disease in diarrheic calves treated for dehydration by causing prolonged abomasal alkalinization.

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in American Journal of Veterinary Research


Objective—To identify cow and management factors associated with colostral IgG concentration in dairy cows.

Design—Prospective observational study.

Animals—81 multiparous Holstein-Friesian cows from a single herd.

Procedures—Serum was obtained at the start of the nonlactating period, and cows were assigned to 1 of 4 photoperiod groups: natural day length (n = 22 cows), long days (16 h of light/d [21]) or short days (8 h of light/d [20]) for the entire nonlactating period, or natural day length followed by short days for the last 21 days of the nonlactating period (18). Serum and colostrum were collected at the first milking after calving. Regression analysis was used to investigate associations between colostral IgG concentration and the interval between calving and first milking, colostral volume, photoperiod, length of the nonlactating period, and season of calving.

Results—Colostral IgG concentration decreased by 3.7% during each subsequent hour after calving because of postparturient secretion by the mammary glands. The interval between calving and first milking and the colostral volume were significantly and negatively associated with colostral IgG concentration, with the former effect predominating. Photoperiod had no effect on colostral IgG concentration or volume. Serum protein concentration at calving correlated poorly with colostral IgG concentration.

Conclusions and Clinical Relevance—Dairy producers should harvest colostrum as soon as possible after calving to optimize transfer of passive immunity in neonatal calves. Photoperiod can be manipulated without adversely affecting colostral IgG concentration.

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in Journal of the American Veterinary Medical Association


Objective—To determine the effect of continuous IV administration of 50% dextrose solution on phosphorus homeostasis in lactating dairy cows.

Design—Clinical trial.

Animals—4 multiparous Jersey cows.

Procedures—Cows were administered 50% dextrose solution IV (0.3 g/kg/h [0.14 g/lb/h]) for 5 days. Plasma concentrations of glucose, immune-reactive insulin (IRI), and phosphorus were determined before, during, and for 72 hours after dextrose infusion. Phosphorus intake and losses of phosphorus in urine, feces, and milk were determined. Each cow received a sham treatment that included instrumentation and sampling but not administration of dextrose.

Results—Plasma glucose, IRI, and phosphorus concentrations were stable during sham treatment. Plasma phosphorus concentration decreased rapidly after onset of dextrose infusion, reaching a nadir in 24 hours and remaining less than baseline value for 36 hours. Plasma phosphorus concentration increased after dextrose infusion was stopped, peaking in 6 hours. Urinary phosphorus excretion did not change during dextrose infusion, but phosphorus intake decreased because of reduced feed intake, followed by decreased fecal phosphorus loss and milk yield. Rapid changes in plasma phosphorus concentration at the start and end of dextrose infusion were temporally associated with changes in plasma glucose and IRI concentrations and most likely caused by compartmental shifts of phosphorus.

Conclusions and Clinical Relevance—Hypophosphatemia developed in response to hyperglycemia or hyperinsulinemia in dairy cows administered dextrose via continuous IV infusion. Veterinarians should monitor plasma phosphorus concentration when administering dextrose in this manner, particularly in cows with decreased appetite or preexisting hypophosphatemia.

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in Journal of the American Veterinary Medical Association