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SUMMARY

The toxicity of Riddell groundsel (Senecio riddellii) gavaged to calves at a known lethal rate was compared with the toxicity of riddelliine and riddelliine N-oxide, the pyrrolizidine alkaloids isolated from the plant, which were fed by intraruminal infusion. Doses of the alkaloids were adjusted to the amount determined to be in the plant and fed individually and in combination. The relative toxicosis in the calves was measured by clinical signs, serum enzyme changes, survival time to morbidity, and histologic changes.

Calves fed Senecio riddellii by gavage for 20 consecutive days to provide 45 mg of total pyrrolizidine alkaloids/kg of body weight/d developed clinical signs and serum enzyme changes typical of seneciosis, with 100% morbidity. However, calves receiving riddelliine at 4.5 mg/kg/d for 20 days had neither serum enzyme changes nor clinical signs of pyrrolizidine alkaloidosis. Calves treated with riddelliine N-oxide (40.5 mg/kg/d), and with riddelliine (4.5 mg/kg/d) and riddelliine N-oxide (40.5 mg/kg/d) in combination, had 100% morbidity, although the latter group had fewer liver lesions.

These results establish that the N-oxide form of the alkaloid alone is capable of inducing typical Senecio toxicosis in cattle and that the free base level of the plant cannot be considered to be the sole factor in assessing the toxicity of S riddellii.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To compare accuracy of estimates of cystolith size obtained by means of plain radiography, double-contrast cystography, ultrasonography, and computed tomography.

Sample Population—30 canine cystoliths ranging from 1 to 11 mm in diameter with various mineral compositions.

Procedures—A bladder phantom model was created by filling a rubber balloon with saline (1% NaCl) solution and positioning it on top of a 2% gelatin cushion at the bottom of a water-filled 4-quart container. Cystoliths were individually placed in the bladder phantom and imaged by each of the 4 techniques. For each image, cystolith size was measured by 2 radiologists with computerized calipers, and size estimates were compared with actual cystolith size.

Results—Mean cystolith size estimates obtained by means of radiography, cystography, and computed tomography did not differ significantly from each other. However, for ultrasonographic images, mean ± SD difference between actual and estimated cystolith size (2.95 ± 0.73 mm) was significantly higher than mean difference for radiographic, cystographic, and computed tomographic images. For ultrasonography, mean ± SD percentage overestimation in cystolith size was 68.4 ± 51.5%.

Conclusions and Clinical Relevance—Results indicated that measurements of cystolith size obtained by means of ultrasonography may overestimate the true size. This suggests that cystolith size estimates obtained by means of ultrasonography should be interpreted with caution whenever cystolith size may influence patient management.

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the efficacy of florfenicol for treatment of calves with naturally occurring infectious bovine keratoconjunctivitis (IBK).

Design—Randomized controlled field trial.

Animals—63 beef calves and 80 dairy calves between 4 and 12 months of age.

Procedure—Calves were randomly assigned to 1 of 3 treatment groups. Calves in the SC treatment group received a single dose of florfenicol (40 mg/kg [18.2 mg/lb] of body weight), SC, on day 0. Calves in the IM treatment group received florfenicol (20 mg/kg [9.1 mg/lb]), IM, on days 0 and 2. Calves in the control group received injections of saline solution (0.9% NaCl), IM, on days 0 and 2. Calves were reevaluated every other day for 20 days after treatment.

Results—Corneal ulcers healed by day 20 in 48 of 49 (98%) calves treated with florfenicol IM, 39 of 42 (93%) calves treated with florfenicol SC, and 33 of 52 (63%) control calves.

Conclusions and Clinical Relevance—Florfenicol administered SC (1 dose) or IM (2 doses 48 hours apart) was effective for treatment of calves with naturally occurring IBK. ( J Am Vet Med Assoc 2000;216: 62–64)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine immunoreactivity of matrix metalloproteinase (MMP)-1, -3, and -13 in cartilaginous tumors of dogs, correlate expression of MMP with histologic grade of tumors and clinical outcome of dogs, and compare MMP immunoreactivity between chondrosarcomas and chondromas.

Sample Population—Formalin-fixed, paraffin-embedded tissues obtained from samples of naturally occurring chondrosarcomas (n = 31) and chondromas (8) of dogs that were submitted to our veterinary medical diagnostic laboratory.

Procedure—Histologic sections from each sample were stained with H&E and monoclonal antibody to MMP-1, -3, and -13 by use of an avidin-peroxidase immunohistochemical technique. For each section, histologic grade (I, II, or III) and immunohistochemical expression (0, 1, 2, or 3) were evaluated. Clinical outcome was obtained from medical records or interviews with referring veterinarians and scored as a good outcome, moderate outcome, or poor outcome. Correlations among variables and differences between chondrosarcomas and chondromas were analyzed.

Results—Samples from chondrosarcomas had significantly higher immunoreactivity of MMP-1 and -13, compared with immunoreactivity in samples from chondromas. In chondrosarcomas, a significant positive correlation (r, 0.386) was found between MMP-1 and -13 immunoreactivities, and a significant negative correlation (r, –0.390) was detected between MMP-3 and -13 immunoreactivities.

Conclusion and Clinical Relevance—A significant increase in expression of collagenases (MMP-1 and - 13) in chondrosarcomas, compared with expression in chondromas, suggests that collagenases may play an important role in tumor progression, and possibly metastasis, in chondrosarcomas of dogs. (Am J Vet Res 2002;63:1285–1291)

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate the clinical and pathologic characteristics of mammary duct ectasia in dogs.

Design—Retrospective study.

Animals—51 dogs with mammary duct ectasia.

Procedure—Information regarding body condition, history, number and location of affected mammary glands, appearance of lesions, surgical treatment, nonsurgical treatment, and evidence of recurrence or development of mammary neoplasia was obtained from surveys sent to referring veterinarians. Results of information from examination of histologic sections and referring veterinarians were evaluated for all mammary duct ectasia biopsies performed between 1992 and 1999.

Results—Duct ectasia was the primary diagnosis in 51 of 1,825 (2.8%) mammary biopsy specimens and comprised 48% of nonneoplastic mammary diseases. Affected dogs were evenly distributed over a range of 1 to 13 years of age, with a mean age at the time of diagnosis of 6.1 ± 3.1 years. All dogs were female (31 sexually intact, 20 spayed); 10 of 26 had whelped. Duct ectasia was described as nodular (26 dogs), cystic (13), and multiglandular (11) and located in caudal (31) more often than cranial (14) or middle glands (10). Ectasia recurred in 3 dogs. One dog had a history of previously excised mammary adenocarcinoma; another subsequently developed mammary carcinoma.

Conclusions and Clinical Relevance—Duct ectasia affected mature, sexually intact and spayed female dogs over a wide age range. Certain breeds were affected more commonly than expected. Increased risk for mammary neoplasia was not evident. Duct ectasia should be considered as a cause for mammary enlargement, especially in young dogs or when its cystic nature is evident. Mastectomy is usually curative, and neoplasia should be ruled out in dogs with ectasia. (J Am Vet Med Assoc 2001;218:1303–1307)

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in Journal of the American Veterinary Medical Association