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Objectives—

To use clinical and lactational characteristics to determine whether bacteriologically negative (BN) clinical mastitis episodes are more apt to be caused by gram-negative or gram-positive bacteria, and to investigate severity of clinical mastitis caused by Corynebacterium spp (COR).

Design—

Case series.

Sample Population—

300 clinical mastitis episodes affecting 123 dairy cows vaccinated against lipopolysaccharide core antigens.

Procedure—

Cows were examined at onset of clinical mastitis, and 23 characteristics, including rectal temperature, heart rate, rumen contraction rate, degree of dehydration, udder and milk characteristics, lactation number, stage of lactation, and season of year, were recorded. Milk production and milk constituent concentrations before onset of mastitis were obtained from herd records. Values for cows with BN milk were compared with values for cows from which milk yielded gram-negative bacteria (GNB) or grampositive cocci (GPC); logistic regression was used to predict which pathogen type was causing BN mastitis. Characteristics for cows from which milk yielded COR were compared with those of cows from which milk was BN or yielded GPC.

Results—

BN clinical mastitis episodes differed significantly from episodes caused by GPC, and were similar to, but milder than, episodes caused by GNB. COR were isolated in a substantial proportion of mastitis episodes, but clinical signs were milder than when GPC were isolated.

Clinical implications—

Most BN mastitis episodes in cows receiving lipopolysaccharide core antigen vaccines appear to be caused by low-grade infection with GNB, and treatment and management decisions should be made accordingly. The COR may be economically important clinical mastitis pathogens in some herds. (J Am Vet Med Assoc 1998;213:855-861)

Free access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

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)

Full access
in Journal of the American Veterinary Medical Association

Objective

To determine whether antibiotic and supportive treatment would improve outcome for dairy cows with naturally developing clinical mastitis, compared with supportive treatment alone.

Design

Randomized controlled trial.

Animals

124 cows in one herd with 172 episodes of clinical mastitis.

Procedure

Cows were examined at the onset of clinical mastitis, assigned a severity score, and randomly assigned to receive antibiotic (intramammary administration of cephapirin, IV administration of oxytetracycline, or both) and supportive treatment (administration of oxytocin, stripping of affected glands, and, in severely affected cows, administration of flunixin meglumine or fluids) or supportive treatment alone. Treatment was continued until 24 hours after signs of clinical mastitis resolved (clinical cure). Milk samples from affected glands were submitted for bacterial culture before initial treatment and every 2 weeks thereafter until the causative organism was no longer isolated (bacteriologic cure).

Results

When mastitis was caused by Streptococcus spp or coliform bacteria, clinical cure rate by the tenth milking was significantly higher if antibiotics were used. Bacteriologic cure rate at 14 days was significantly higher when antibiotics were used, particularly if mastitis was caused by Streptococcus spp. Cows receiving antibiotics developed fewer subsequent episodes of clinical mastitis during the 60 days after the initial episode of mastitis and had less severe clinical disease than cows that did not.

Clinical Implications

Results suggest that, in herds in which mastitis is often caused by environmental bacteria, antibiotic and supportive treatment may result in a better outcome for cows with clinical mastitis than supportive treatment alone. (J Am Vet Med Assoc 1998;213:676-684)

Free access
in Journal of the American Veterinary Medical Association

Abstract

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)

Full access
in Journal of the American Veterinary Medical Association

Abstract

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)

Full access
in Journal of the American Veterinary Medical Association

Objective

To develop accurate, objective guidelines for assessing hydration status of neonatal calves with diarrhea.

Design

Prospective study.

Animals

15 male dairy calves 3 to 10 days old.

Procedure

Dehydration and diarrhea were induced by administration of diuretic agents (ie, furosemide, spironolactone, hydrochlorothiazide) and sucrose solution. Linear regression was used to examine the relationship between potentially useful factors for evaluating hydration status (extent of enophthalmos; skin-tent duration on neck, thorax, and upper and lower eyelids; heart rate; mean central venous pressure; peripheral [extremity] and core [rectal] temperatures; core-peripheral [rectal-extremity] temperature difference; PCV; and hemoglobin and plasma protein concentrations) and degree of dehydration, as determined by change in body weight.

Results

Best predictors of degree of dehydration were extent of enophthalmos, skin elasticity on neck and thorax, and plasma protein concentration.

Clinical Implications

These experimentally determined guidelines provide practitioners with a simple, inexpensive, and practical method for evaluating hydration status of neonatal calves with diarrhea. (J Am Vet Med Assoc 1998;212:991–996)

Free access
in Journal of the American Veterinary Medical Association

Objective

To determine whether clinical parameters could be used to differentiate clinical mastitis (CM) caused by gram-positive bacteria from CM caused by gram-negative bacteria in dairy cows vaccinated against lipopolysaccharide core antigens.

Design

Case series.

Animals

143 episodes of CM in 86 dairy cows in a single herd.

Procedure

Cows were examined at onset of CM, and 24 clinical parameters including rectal temperature, heart rate, rumen contraction rate, degree of dehydration, various udder and milk characteristics, lactation number, stage of lactation, and season of year were recorded. Milk production and milk constituent concentrations before onset of CM were obtained from Dairy Herd Improvement Association records. Values for cows with gram-negative CM were compared with values for cows with gram-positive CM. Logistic regression was used to identify important predictors of gram-negative CM.

Results

64 (45%) CM episodes were caused by gram-negative bacteria and 79 (55%) were caused by gram-positive bacteria. Rumen contraction rate was significantly lower and milk protein percentage before onset of CM was significantly higher in cows with gram-negative, rather than gram-positive, CM. Logistic regression indicated that CM was more likely to have been caused by gram-negative bacteria if it developed during the summer, milk was watery, or rumen contraction rate was low. Sensitivity and specificity of the final regression model were 0.58 and 0.80, respectively. Predictive value of a positive result was 0.74 when proportion of CM episodes caused by gram-negative bacteria was assumed to be 50%.

Clinical Implications

Results suggest that clinical observations do not allow accurate prediction of CM pathogens and should not be the sole criteria for deciding whether cows with CM are treated with antibiotics. (J Am Vet Med Assoc 1998;212:1423–1431)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine effectiveness of a new and practical method for fluid resuscitation of dehydrated diarrheic calves.

Design

Animals randomly allocated to 4 groups with appropriate controls.

Animals

16 healthy male dairy calves, 3 to 6 days old.

Procedure

After instrumentation and recording baseline data, diarrhea and hypovolemia were induced by administering milk replacer (33 ml/kg of body weight) and isotonic sucrose solution (2 g of sucrose in 19.5 ml of water/kg, PO) every 8 hours, and furosemide (2 mg/kg, IM) every 4 to 8 hours. Administration of milk replacer and furosemide was discontinued when calves became 6% dehydrated. Calves were then randomly allocated as: control (no treatment); hypertonic saline-dextran (HSD) solution (4 ml/kg, 2,400 mOsm/L NaCl in 6% dextran-70, administered once over 4 minutes, IV); isotonic alkalinizing oral electrolyte solution (55 ml/kg, PO, q 8 h); and HSD-oral electrolyte solution (combination of HSD and oral treatments). Calves were monitored for 24 hours after treatment.

Results

Significant changes included moderate dehydration (8% body weight), marked lethargy, decreased cardiac output and plasma volume, and increased blood lactate concentration, hematocrit, and serum concentrations of albumin, creatinine, sodium, and phosphate. Control calves continued to be lethargic and dehydrated, with significant increases in hematocrit and serum creatinine concentration. Increase in cardiac output and plasma volume was transient in the HSD group and waned by 2 to 8 hours after treatment. Oral electrolyte fluid administration caused slow and sustained increase in cardiac output and plasma volume, and decrease in heart rate, blood lactate concentration, and hematocrit. Combined administration of HSD-oral electrolyte solution caused immediate and sustained increase in cardiac output and plasma volume, and decrease in heart rate, blood lactate concentration, and hematocrit.

Conclusions and Clinical Relevance

Treatment of hypovolemic diarrheic calves with IV HSD and oral electrolyte solution is superior to administration of either solution alone. (Am J Vet Res 1996;57:97-104)

Free access
in American Journal of Veterinary Research