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
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
Objective—To identify risk factors associated with
dysautonomia in dogs.
Animals—42 dogs with dysautonomia examined
between October 1988 and January 2000 and 132
control dogs examined during the same period for an
Procedure—Information was gathered from medical
records and surveys mailed to owners of case and
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:
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
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
Objective—To evaluate the clinical and pathologic
characteristics of mammary duct ectasia in dogs.
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)