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- Author or Editor: Gayle C. Johnson x
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Abstract
Objective—To determine whether cattle exposed to heat stress alone or heat stress while consuming endophyte-infected fescue (EIF) have lower wholeblood (WB) concentrations of glutathione (GSH).
Animals—10 Simmental cows.
Procedure—Cows were sequentially exposed to thermoneutral (TN; 2 weeks; 18 C, 50% relative humidity [RH]), heat stress (HS; 2 weeks; alternating 4-hour intervals at 26 and 33 C; 50% RH), and heat stress while consuming EIF (10 µg of ergovaline/kg/d; 2 weeks; HS + EIF). Blood samples were collected after each period and tested for GSH and oxidized glutathione (GSSG) concentrations.
Results—Feed consumption was similar when data were analyzed for time points at which WB concentrations of GSH or GSSG were determined. However, significant effects of treatment, cow, days exposed to heat, cow-by-treatment interaction, and treatment-bydays exposed to heat interaction were detected when data were considered simultaneously. Mean ± SD hematocrit for TN, HS, and HS + EIF were 35.3 ± 3, 33.3 ± 2, and 37.1 ± 3%, respectively. Mean WBGSH concentrations for TN, HS, and HS + EIF were 3.2 ± 0.65, 2.7 ± 0.62, and 2.4 ± 0.56 mmol/L of RBC, respectively. Reduced WBGSH concentrations were associated with reduced feed intake during the later part of each heat period.
Conclusion and Clinical Relevance—Decreased GSH and increased GSSG concentrations were evident during heat stress, especially when cattle consumed EIF. These were associated with reduced feed intake during heat stress. Heat stress, reductions in feed intake, and thermoregulatory effects of EIF may induce oxidative stress in cattle. (Am J Vet Res 2002;63:799–803)
Abstract
Objective—To identify risk factors associated with dysautonomia in dogs.
Design—Case-control study.
Animals—42 dogs with dysautonomia examined between October 1988 and January 2000 and 132 control dogs examined during the same period for an unrelated problem.
Procedure—Information was gathered from medical records and surveys mailed to owners of case and control dogs.
Results—42 case and 132 control dogs were included; completed surveys were returned by owners of 30 case and 103 control dogs. Dogs with dysautonomia were significantly younger (median, 18 months) than control dogs (median, 60 months) and more likely to come from rural areas and to spend ≥ 50% of their time outdoors. Compared with rural control dogs that spent at least some time outdoors, affected dogs were more likely to have access to pasture land, farm ponds, and cattle, and to have consumed wildlife, at least occasionally. The largest numbers of dogs with dysautonomia were identified during February and April, with relatively few dogs identified during the summer and early fall.
Conclusion and Clinical Relevance—Although the cause of dysautonomia is unknown, results suggest that dogs with dysautonomia were significantly more likely to live in rural areas and spend ≥ 50% of their time outdoors than were control dogs examined for unrelated diseases. (J Am Vet Med Assoc 2001;218: 1285–1290)
Abstract
In collaboration with the American College of Veterinary Pathologists
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)
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)
