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Summary

Nine adult female sheep were each surgically fitted with an Ivan and Johnston reentrant cannula in the cranial part of the duodenum just distal to the pylorus. By diversion (loss) of abomasal outflow, this model has been shown to consistently induce hypochloremic, hypokalemic metabolic alkalosis, accompanied by hyponatremia and dehydration. Each sheep was subjected to 3 treatment trials, each preceded by a 24-hour prediversion period, and a diversion period during which a syndrome of hypochloremia (68 ± 2 mEq/L), hypokalemia, hyponatremia, and metabolic alkalosis was induced.

Development of this syndrome was attributable to losses of large amounts of acid and electrolytes in the abomasal effluent. Mean total electrolyte contents of the effluent were: Cl, 650 ± 27 mEq; Na+, 388 ± 23 mEq; and K+, 123 ± 12 mEq, with total volume loss ranging from 3.6 to 10.0 L of gastric contents and pH ranging from 3 to 5. Decreases in plasma electrolyte concentrations also can be attributed to decreased intake, because anorexia developed shortly after the onset of diversion. Electrolyte losses in urine during diversion were minimal for Cl (mean ± sem, 12.0 ± 5.1 mEq), but were greater for Na+ (124.2 ± 14.5 mEq) and K+ (185.1 ± 31.2 mEq).

Treatments consisted of 0.9% NaCl (300 mosm/L), 3.6% NaCl (1,200 mosm/L), and 7.2% NaCl (2,400 mosm/L) administered over a 2-hour period, with the administered volume determined by the estimated total extracellular fluid Cl deficit. Significant difference was not found among treatments, with all solutions resulting in return of clinicopathologic and physical variables to prediversion values within 12 hours of treatment. We concluded that rapid iv replacement of Cl, with small volumes of hypertonic saline solution, is safe and effective for correction of experimentally induced hypochloremic, hypokalemic, metabolic alkalosis in sheep.

Free access
in American Journal of Veterinary Research

Summary

Clinical and surgical findings in 458 dairy cows with right displacement of the abomasum or abomasal volvulus (av) were analyzed to determine the association between these variables and the outcome (productive, salvaged, or terminal) of the affected cow.

Heart rate at initial examination was higher in the salvaged and terminal groups of cows (P < 0.0001) than in the productive group. The plasma Na+ concentration was lower in the salvaged and terminal groups of cows (P < 0.0001) than in the productive group. The plasma C1 concentration was lower in the salvaged group of cows than in cows with either productive or terminal outcomes (P < 0.0001). Anion gap was significantly higher (P < 0.0001) in the salvaged and terminal groups than in cows classified as productive.

On the basis of surgical findings, cattle with right displacement of the abomasum were more likely to survive than cows with av. Cows that required fluid decompression of the abomasum via abomasotomy were less likely to survive than those in which gaseous decompression was performed. Cows with evidence of vascular compromise of the abomasal wall were less likely to survive than those with normal abomasal serosa.

Preoperative heart rate and anion gap had positive correlations with the presence of abomasal necrosis, whereas temperature, venous blood pH, plasma bicarbonate, and base excess concentrations had negative correlations.

Cows in terminal stages of av were likely to have a mixed primary acid-base disturbance, consisting of metabolic alkalosis with superimposed metabolic acidosis. These findings were highly correlated with abomasal necrosis.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To quantify the effect of early-lactation milk and milk fat production on time to conception.

Design

Event-time analysis (survival analysis).

Sample Population

44,450 cows delivering calves between September 1985 and September 1986, from 6,227 Ayrshire dairy herds in 80 Finnish communities.

Procedure

Primiparous and multiparous cows were analyzed in separate Cox proportional hazards models. 60-day milk and milk fat production were categorized and regressed against days from parturition to conception for the period 56 to 120 postpartum days, controlling for season of parturition, parity, herd production, occurrence of 43 diseases, and community.

Results

Multiparous cows producing above the 80th percentile for 60-day milk, but with milk fat production below the 75th percentile, were significantly more likely to conceive, compared with cows with lower production and compared with cows with similar milk production but with milk fat between the 75th and 97th percentiles. They were slightly more likely to conceive than cows with highest milk fat production, although not significantly so. Primiparous cows producing above the 80th percentile for 60-day milk with milk fat below the 75th percentile also had the highest conception probability. The highest producing primiparae had significantly lower conception probability than all others.

Conclusions

Controlling for disease occurrence, calving season, parity, herd production level, and community, there appeared to be an inverted U-shaped relation between 60-day production and conception probability.

Clinical Relevance

Primiparous cows that are high producers may not be receiving the same careful management that high-producing multiparous cows receive. (Am J Vet Res 1996; 57:634–639)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To quantify the effect of season of parturition, parity, and various diseases on time to conception.

Design

Event-time analysis (survival analysis).

Sample Population

44,450 cows delivering calves between September 1985 and September 1986, from 6,227 Ayrshire dairy herds in 80 Finnish communities.

Procedure

Primiparous and multiparous cows were analyzed in separate Cox proportional hazards models for postpartum days 56 to 120. Occurrence of 43 diseases or disorders was recorded; codes were condensed into 25 variables offered to each model. Season of parturition was categorized into spring, summer, and fall-winter; for multiparous cows, 3 categorical variables represented parity. Models controlled for 60-day milk and milk fat production, herd milk production, and community. For all observations, parturition-to-conception interval was plotted against calendar day of parturition.

Results

For multiparous cows, parturition in the spring or summer and being of parity 2 or 3-4 (vs older) increased the chance of conceiving; 10 diseases or disorders decreased this probability. Similarly, in the model for primiparae, parturition in spring or summer increased the probability of conception, and 6 disorders decreased it. Disorders that were detrimental in both models were anestrus, ovulatory dysfunction, other infertility, late metritis, and clinical ketosis.

Conclusions

The effect of season on the parturition- to-conception interval was marked at this latitude. Parturition during late April, causing confluence of postpartum day 55 with the summer solstice, was associated with the shortest parturition-to-conception intervals. Ketosis was found to be an important factor in lengthening the parturition-to-conception interval, highlighting the effect of negative energy balance on postpartum restoration of reproductive function. (Am J Vet Res 1996; 57:640–645)

Free access
in American Journal of Veterinary Research

SUMMARY

Data at admission and at surgery were collected on 458 cows with right displacement of the abomasum or abomasal volvulus, to derive multiple logistic regression models for predicting postsurgical outcome (productive, salvaged, or terminal). The derived models contained few and easily obtained variables. The weight associated with each variable was determined objectively. Three admission variables (heart rate, base excess, and plasma chloride concentration), and 5 surgical variables (heart rate, base excess, diagnosis, method of decompression used, and appearance of abomasal serosa) were used in the final models. Predicted outcomes that used the admission and surgical models were closely related with actual outcomes. Total correct classification for satisfactory (productive) versus unsatisfactory outcome (salvaged and terminal) was 78.2% for the admission model and 82.7% for the surgical model. Combining data on cows with productive and salvaged outcomes as satisfactory outcome, and terminal as unsatisfactory outcome, total correct classification was 90.7% for the admission model and 93.2% for the surgical model. Using predicted probabilities, the market value of productive and salvaged cows, and the medical and surgical costs, one can calculate the expected economic value of each outcome. Treatment can be justified if the sum of the expected value of productive and salvaged outcome exceeds the sum of the medical and surgical costs and the expected salvaged value of the cow that was not treated surgically.

Free access
in American Journal of Veterinary Research

SUMMARY

Five adult 40- to 50-kg female sheep were surgically fitted with a reentrant cannulae placed in the proximal part of the duodenum just distal to the pylorus. By diversion of abomasal outflow, this model has been shown to produce hypochloremic metabolic alkalosis accompanied by dehydration, hypokalemia, and hyponatremia. Each sheep was subjected to 3 separate, 12-hour iv treatment trials, in each case preceded by a control period of 48 hours, and a diversion period of 36 to 96 hours, during which a hypochloremic (Cl ≤ 60 ± 2 mEq/L) metabolic alkalosis with hypokalemia and hyponatremia was produced.

Treatment 1, consisting of 6 L of isotonic Na gluconate, was designed to replace volume without replenishing the Cl deficit. Although hydration improved, plasma Cl decreased further, and the sheep became increasingly weak and depressed. Treatment 2, consisting of 2 L of 1.8% NaCl, was designed to replace the Cl deficit without replacing total volume. Plasma Na+ and Cl concentrations returned to normal during the 12 hours of treatment; acid-base balance and plasma K+ concentrations returned to normal within 36 hours of treatment. During treatment 3 (control, no treatment), measured metabolic values changed minimally. We concluded that the iv replacement of Cl without K+ is effective in the correction of experimentally induced hypochloremic metabolic alkalosis in sheep.

Free access
in American Journal of Veterinary Research

Objective

To compare the effect of a single parenteral injection of tilmicosin with that of a single dose of a long-acting oxytetracycline as treatment in the early stages of naturally acquired undifferentiated respiratory tract disease in young dairy calves.

Design

Prospective clinical trial, randomized block design.

Animals

40 dairy calves.

Procedure

78 calves from 5 farms were examined weekly until 3 months old. When respiratory tract disease was diagnosed by a veterinarian, the calf was assigned to 1 of 2 treatment groups. Transtracheal wash samples were acquired to characterize the pathogens. The veterinarian, who was unaware of treatment assignments, examined calves for 3 days after treatment and evaluated severity, using a scoring system. Growth rates were measured.

Results

On the basis of response to initial treatment, relapse rates, and effect on growth rates, the antibiotics were determined to be equally effective. Severity of clinical disease was significantly (P < 0.03) less for the tilmicosin-treated calves on days 2 and 3 after treatment. Findings from analysis of transtracheal wash samples indicated Pasteurella multocida (25/40), P haemolytica (4/40), Haemophilus somnus (4/40), Actinomyces pyogenes (3/40), and Aspergillus sp (2/40). Mycoplasma was isolated in association with bacterial isolates in 22 calves.

Clinical Implications

Tilmicosin and oxytetracycline are effective in treatment of respiratory tract disease in young calves, even when Mycoplasma spp are involved. Tilmicosin is more effective in resolving clinical signs. Early treatment of dairy calves with respiratory tract disease may decrease detrimental effects on growth.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

A double-blinded randomized prospective clinical trial was designed to evaluate the effectiveness of flunixin meglumine and phenylbutazone for treatment of acute toxic mastitis in dairy cows. All cows were treated 4 times at 12-hour intervals by intramammary infusion of gentamicin (150 mg). A total of 45 dairy cows with toxic mastitis were randomly assigned to 1 of 3 treatment groups: group 1 (control), saline solution, iv; group 2,1 g of flunixin meglumine, iv; or group 3, 4 g of phenylbutazone, iv. Physical examination and udder variables were assessed at initial examination and 24 hours later. Milk production was recorded at regular intervals from 1 week before until 10 weeks after development of mastitis.

Rear quarters (34/45) were more commonly affected than front quarters. Thirty-five cows returned to the herd, 9 cows were culled, and 1 cow died. There were no significant differences among treatment groups in the need for further treatment or outcome. Klebsiella spp (18/45) and Escherichia coli (16/45) were the most common pathogens isolated by culture of milk from affected quarters. The overall bacteriologic cure rate on days 7 and 14 was 64 and 75%, respectively.

At the time of initial examination, cows of the control group had higher rectal temperature than did cows of the flunixin group. At the examination 24 hours later, the rectal temperature of cows in all treatment groups was lower than the temperature at initial examination; at that time (24 hours), however, there were no significant differences in temperature among the treatment groups.

Adjusted for stage of lactation, calving season, and parity, mastitic cows, compared with nonmastitic cows from the same herd, had lower milk production in the 10 weeks after development of mastitis, particularly during the week of onset. In repeated measures models, the loss of milk associated with mastitis was not significantly different among the 3 treatment groups.

Free access
in American Journal of Veterinary Research