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  • Author or Editor: Merle E. Olson x
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SUMMARY

Antagonism of ketamine-xylazine (85 mg of ketamine/ kg of body weight and 15 mg of xylazine/kg, im) anesthesia in rats by yohimbine (yoh; 1, 5, 10, and 20 mg/kg, ip), tolazoline (tol; 10, 20, or 50 mg/kg, ip), 4-aminopyridine (4-AP; 1 or 5 mg/kg, ip), or a combination of yohimbine and 4-aminopyridine (yoh:4-AP, 1 mg/kg: 1 mg/kg or 5 mg/kg: 1 mg/kg, ip) was studied. All dosages of yoh, tol, 4-AP, and yoh:4-AP reduced the time to appearance of corneal and pedal reflexes. Only tol was effective in reducing time to appearance of the crawl reflex and recovery time. Yohimbine, 4-AP, yoh:4-AP, and tol were effective in reversing respiratory depression caused by ketamine-xylazine anesthesia, but anesthetic-induced hypothermia was not antagonized. When given to nonanesthetized rats, the antagonists had little influence on respiratory rate, but all antagonists caused significant (P < 0.05) reduction in core body temperature for at least 90 minutes. When yoh was used as an anesthetic antagonist at dosage of 20 mg/kg, 20% mortality was observed and was attributable to acute respiratory arrest. The use of 4-AP and yoh:4-AP at the dosages studied induced moderate to severe muscular tremors. In conclusion, tol at dosage of 20 mg/kg given ip, appears to be an appropriate antagonist for ketamine-xylazine anesthesia in rats.

Free access
in American Journal of Veterinary Research

SUMMARY

Nonsteroidal anti-inflammatory drugs (nsaid) are widely used for treatment of people and animals. Their use is limited by frequent side effects commonly involving the gastrointestinal tract, most important of which is development of ulcerating lesions principally in the stomach. Unfortunately, presence of such lesions is often unsuspected because clinical signs may be overlooked until a complication develops. We reported that such damage can be detected by measuring the increase in gastric permeability that is a hallmark of this condition. Sucrose is a novel probe molecule for determination of site-specific gastric permeability. As a disaccharide, it is large enough to be effectively excluded by the intact gastric epithelium, and because it is rapidly digested within the small intestine, absorption of the intact molecule implies damage proximal to this site. Recently, we found that increased sucrose permeability is useful in predicting presence of endoscopically relevant gastric damage in people. We extended these results to the detection of nsaid-induced gastropathy in dogs. Dogs treated with aspirin developed nsaid-induced gastropathy (including gastric ulceration), and the degree of endoscopically detectable damage correlated well with sucrose permeability. Furthermore, healing of these lesions could also be monitored by sequential measurements of sucrose permeability. Sucrose permeability decreased more rapidly than the disappearance of gastric ulcers, suggesting that this technique is more sensitive to generalized mucosal damage than is the presence of discrete, endoscopically visible ulceration. This was confirmed by creating artificial ulcers in the antrum and observing that sucrose permeability was not increased in this setting. We conclude that determination of increased sucrose permeability is a useful, noninvasive means of predicting presence of gastric damage in dogs treated with nsaid.

Free access
in American Journal of Veterinary Research

Summary:

The prophylactic administration of injectable tilmicosin for pneumonia in weaned beef calves was investigated in 1,806 animals. Comparisons were made among calves receiving an “on-arrival” injection of tilmicosin, calves receiving a single injection of long-acting oxytetracycline, and calves receiving no prophylaxis. Morbidity and mortality attributable to pneumonia, morbidity and mortality attributable to all causes, and case fatality were significantly lower in the group of calves that received tilmicosin, compared with calves that received long-acting oxytetracycline and calves that received no prophylactic antibiotic. Mean time to initial pneumonia treatment was significantly extended in calves that received prophylaxis, compared with those that received no antibiotic on arrival at the feedlot. Calves that received tilmicosin gained significantly more weight than calves that received oxy tetracycline. Calves that were not treated for pneumonia during the trial period gained significantly more weight than did those calves that were treated for pneumonia regardless of experimental group.

The majority of mortalities were attributable to fibrinous pneumonia (31/34). Important bacterial isolates (Pasteurella spp, Haemophilus somnus, Actinomyces pyogenes) obtained at necropsy did not have resistance to tilmicosin in association with administration of tilmicosin as prophylaxis for pneumonia. However, bacterial resistance to trimethoprim/sulfonamide and to oxytetracycline were commonly found in these postmortem isolates.

Free access
in Journal of the American Veterinary Medical Association

Objective

To determine duration of infection and association of infection with diarrhea for dairy calves with naturally acquired cryptosporidiosis and giardiosis.

Design

Cohort study.

Animals

20 Holstein calves on a single dairy farm.

Procedure

Fecal samples were collected 3 times/wk for the first 45 days after birth, then weekly until calves were 120 days old and examined for Giardia duodenalis cysts and Cryptosporidium parvum oocysts. Calves were monitored for diarrhea during the first 45 days after birth; during each episode of diarrhea, fecal samples were examined for parasitic, bacterial, and viral pathogens.

Results

All 20 calves shed Giardia cysts and Cryptosporidium oocysts at some time during the study. Mean ages at which Giardia cysts and Cryptosporidium oocysts were first detected were 31.5 and 16.3 days, respectively. Mean number of Giardia cysts in feces remained high throughout the study, whereas Cryptosporidium oocysts decreased to low or undetectable numbers 2 weeks after infection. Eighteen calves had a total of 38 episodes of diarrhea during the first 45 days after birth. Giardia duodenalis was the only pathogen identified during 6 (16%) episodes, C parvum was the only pathogen identified during 9 (24%) episodes, and G duodenalis and C parvum were identified together during 10 (26%) episodes.

Conclusions

Prevalences of giardiosis and cryptosporidiosis were high in these calves, and both parasites were associated with development of diarrhea. Cryptosporidium parvum was an important pathogen when calves were < 1 month old, but G duodenalis was more important when calves were older. Calves cleared C parvum infections within 2 weeks; however, G duodenalis infections became chronic in these calves. (J Am Vet Med Assoc 1999;214:391–396)

Free access
in Journal of the American Veterinary Medical Association

Objective—

To determine whether ceftiofur sodium would be useful for treatment of acute interdigital phlegmon (foot rot) in cattle.

Design—

Randomized controlled trial.

Animals—

308 cross-bred yearling steers with clinical signs of acute interdigital phlegmon (ie, lameness with interdigital swelling, interdigital lesions, or both).

Procedure—

Steers were randomly assigned to 1 of 3 treatment groups: ceftiofur at a dosage of 0.1 mg/kg (0.045 mg/lb) of body weight, IM, every 24 hours; ceftiofur at a dosage of 1.0 mg/kg (0.45 mg/lb), IM, every 24 hours, and oxytetracycline at a dosage of 6.6 mg/kg (3 mg/lb), IM, every 24 hours. All animals were treated for 3 days; treatment was considered successful if animals were no longer lame on day 4. Biopsy specimens were collected prior to treatment from 5 animals in each group and submitted for anaerobic bacterial culture and histologic examination.

Results—

Success rates for the high-dosage ceftiofur (94/129; 73%) and oxytetracycline (87/128; 68%) groups were significantly higher than that for the low-dosage ceftiofur group (5/50; 10%), but there were no significant differences between the high-dosage ceftiofur and oxytetracycline groups. Anaerobic bacteria most frequently isolated from biopsy specimens were Porphyromonas levii and Provetella intermedia.

Clinical Implications—

Use of ceftiofur at a dosage of 1.0 mg/kg for treatment of cattle with acute interdigital phlegmon was as effective as use of oxytetracycline at a dosage of 6.6 mg/kg. However, ceftiofur has a negligible withdrawal time and, therefore, may be a better choice for treatment of near-market weight animals. (J Am Vet Med Assoc 1998;212:254–257)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objectives

To determine tilmicosin concentrations in serum and tissues of rabbits given a single dose of 25 mg of tilmicosin/kg of body weight. To examine the effects of tilmicosin treatment (25 mg/kg, SC) in rabbits with pasteurellosis.

Procedure

After receipt of tilmicosin, healthy New Zealand White female rabbits (n = 3 at each time) were euthanatized at 2, 4, 8, 24, 48, and 72 hours for collection of blood samples and tissue specimens; 4 rabbits served as untreated controls. Rabbits (male and female) with pasteurellosis (n = 42) also were treated. Tilmicosin concentration was determined in serum, lung, and uterine tissues. Rabbits with pasteurellosis were treated with tilmicosin. Response was monitored, using bacteriologic culturing and antibiotic resistance and susceptibility testing, and by scoring clinical signs of disease.

Results

Serum tilmicosin concentration reached 1.91 ±0.18 μg/ml after 2 hours, decreased to 0.77 ± 0.07 μg/ml by 8 hours, and was below minimum inhibitory concentrations for Pasteurella multocida at 24 hours. Terminal half-life in serum was 5.97 hours. Lung and uterus concentrations were 14.43 ± 1.34 and 11.57 ± 0.09 ppm at 2 hours, and were 5.10 ± 1.05 and 8.87 ± 1.66 ppm at 24 hours, respectively. 69% (29/42) of rabbits with pasteurellosis responded favorably in 3 days. Second treatment was required in 31% (13/42), and 5 of these rabbits had clinical signs on day 6; 2 of these 5 had improved. Treatment success rate was 93% (39/42). Of the rabbits that were culture positive on day 0, 35% (6/17) remained positive on day 3. 1 of 6 rabbits was culture positive on day 6.

Conclusion

Tilmicosin (25 mg/kg, SC) was an effective treatment for pasteurellosis in New Zealand White rabbits.

Clinical Relevance

Tilmicosin treatment of pasteurellosis in rabbits is useful in research rabbits and in those destined for meat production. A single dose of antibiotic minimizes stress-associated handling. (Am J Vet Res 1996;57:1180-1184)

Free access
in American Journal of Veterinary Research