OBJECTIVE To evaluate the clinical performance of a veterinary benchtop dry chemistry analyzer for measurement of plasma ammonium concentrations in dogs by comparing results with those obtained by a reference standard test method.
DESIGN Prospective evaluation study.
SAMPLE 32 blood samples from 30 dogs (16 with and 14 without suspected hepatobiliary disease).
PROCEDURES Blood samples were collected by jugular venipuncture. A veterinary benchtop dry chemistry analyzer and a reference standard (enzymatic) test method were used to measure ammonium concentrations in plasma collected from heparinized whole blood. Bland-Altman plots were used to assess intermethod agreement. Results were compared by linear regression, and correlation was calculated by the Pearson method. Samples were classified as having high or normal ammonium concentrations on the basis of cutoff data for the relevant test method; results were compared between methods to evaluate diagnostic agreement.
RESULTS 31 of 32 (97%) samples were classified correctly with the benchtop analyzer; 1 sample with a high ammonium concentration was classified as having a normal value (ie, false-negative result) by this method. A strong positive correlation (r2 = 0.989) was found between methods, with constant, proportional, negative bias for benchtop analyzer results. The interassay coefficient of variation (ie, precision) for measurement of an internal standard with the benchtop analyzer was 2.74% (n = 20 repetitions).
CONCLUSIONS AND CLINICAL RELEVANCE The dry chemistry analyzer used in the study had acceptable clinical performance for detection of high versus normal ammonium concentrations in canine plasma, indicating the method can be used to aid diagnosis in dogs with suspected hepatobiliary disease.
Objective—To investigate postprandial changes in
serum concentrations of unconjugated bile acids in
Animals—7 healthy Beagles.
Procedure—Blood samples were obtained from dogs
at regular intervals up to 8 hours after consumption of
a meal. Serum concentrations of 5 unconjugated bile
acids were determined at each time point, using gas
chromatography-mass spectrometry with selected
Results—Total serum unconjugated bile acid concentration
was significantly increased, relative to baseline
values, at 360, 420, and 480 minutes after feeding.
Unconjugated cholic acid was significantly increased
at 360, 420, and 480 minutes. The proportion of total
unconjugated bile acids represented by cholic acid
was significantly increased at 240 to 480 minutes.
Deoxycholic acid was significantly increased at 360
and 420 minutes. Chenodeoxycholic acid was significantly
increased at 360 to 480 minutes. Lithocholic
acid was significantly increased at 180 minutes,
whereas no significant changes in ursodeoxycholic
acid were detected at any time point.
Conclusion and Clinical Relevance—Healthy
Beagles had significant increases in serum concentrations
and changes in the profile of unconjugated bile
acids after a meal. These increases persisted > 8 hours,
indicating that prolonged withholding of food is necessary
when to avoid the risk of a false-positive diagnosis
when assessing serum unconjugated bile acid concentrations
in dogs. (Am J Vet Res 2002;63:789–793
Objective—To validate an automated chemiluminescent
immunoassay for measuring serum cobalamin
concentration in cats, to establish and validate gas
chromatography-mass spectrometry techniques for
use in quantification of methylmalonic acid, homocysteine,
cysteine, cystathionine, and methionine in sera
from cats, and to investigate serum concentrations of
methylmalonic acid, methionine, homocysteine, cystathionine,
and cysteine as indicators of biochemical
abnormalities accompanying severe cobalamin (vitamin
B12) deficiency in cats.
Sample Population—Serum samples of 40 cats with
severe cobalamin deficiency (serum cobalamin concentration
< 100 ng/L) and 24 control cats with serum
cobalamin concentration within the reference range.
Procedure—Serum concentrations of cobalamin
were measured, using a commercial automated
chemiluminescent immunoassay. Serum concentrations
of methylmalonic acid, methionine, homocysteine,
cystathionine, and cysteine were measured,
using gas chromatography-mass spectrometry,
selected ion monitoring, stable-isotope dilution
Results—Cats with cobalamin deficiency had significant
increases in mean serum concentrations of
methylmalonic acid (9,607 nmol/L), compared with
healthy cats (448 nmol/L). Affected cats also had substantial
disturbances in amino acid metabolism, compared
with healthy cats, with significantly increased
serum concentrations of methionine (133.8 vs 101.1
µmol/L) and significantly decreased serum concentrations
of cystathionine (449.6 vs 573.2 nmol/L) and
cysteine (142.3 vs 163.9 µmol/L). There was not a significant
difference in serum concentrations of homocysteine
between the 2 groups.
Conclusions and Clinical Relevance—Cats with
gastrointestinal tract disease may have abnormalities
in amino acid metabolism consistent with cobalamin
deficiency. Parenteral administration of cobalamin
may be necessary to correct these biochemical
abnormalities. (Am J Vet Res 2001;62:1852–1858)
Objective—To develop and validate a gas chromatography–mass spectrometry (GC-MS) method for determination of Nτ-methylhistamine (NMH) concentration in canine urine and fecal extracts and to assess urinary NMH concentrations in dogs with mast cell neoplasia and fecal NMH concentrations in dogs with protein-losing enteropathy.
Sample Population—Urine specimens were collected from 6 healthy dogs and 7 dogs with mast cell neoplasia. Fecal extracts were obtained from fecal specimens of 28 dogs with various severities of protein-losing enteropathy, as indicated by fecal concentration of α1-proteinase inhibitor.
Procedures—NMH was extracted directly from urine, and fecal specimens were first extracted into 5 volumes of PBSS containing 1% newborn calf serum. Nτ-methylhistamine in specimens was quantified via stable isotope dilution GC-MS. The assay was validated via determination of percentage recovery of known amounts of NMH and interassay coefficients of variation. Urinary excretion of NMH was evaluated by means of NMH-to-creatinine concentration ratios.
Results—Recovery of NMH in urine and fecal extracts averaged 104.6% and 104.5%, respectively. Interassay coefficients of variation ranged from 5.4% to 11.7% in urine and 12.6% to 18.1% in fecal extracts. Urinary NMH excretion was significantly increased in dogs with mast cell neoplasia, compared with that in healthy dogs. No correlation was detected between severity of protein-losing enteropathy and fecal NMH concentration.
Conclusions and Clinical Relevance—This method provided a sensitive, reproducible means of measuring NMH in canine urine and fecal extracts. High urinary NMH-to-creatinine concentration ratios in dogs with mast cell neoplasia are consistent with increased histamine release in this disease.
OBJECTIVE To assess clinical effects of an omega-3 fatty acid and protein-enriched diet, physical rehabilitation, or both in dogs following tibial plateau leveling osteotomy (TPLO) and arthroscopic surgery for cranial cruciate ligament (CCL) disease.
DESIGN Randomized, prospective clinical trial.
ANIMALS 48 dogs with unilateral CCL disease.
PROCEDURES Dogs were randomly assigned to receive a dry omega-3 fatty acid and protein-enriched dog food formulated to support joint health (test food [TF]), a dry food formulated for maintenance of adult dogs (control food [CF]), TF plus rehabilitation (TF-R), or CF plus rehabilitation (CF-R). Data collected over 6 months included body weight, body condition score, ground reaction force data, tibial plateau angle, limb circumference measurements, subjective pain and lameness scores assigned by surgeons and dog owners, and daily activity measured by accelerometry.
RESULTS Peak vertical force and vertical impulse were greater after surgery for dogs in the TF groups than in the CF groups; peak vertical force was greater after surgery in dogs that underwent rehabilitation than in those that did not. Owner scores indicated lower frequencies of lameness and signs of pain during some activities for the TF group, compared with other groups, and for the TF-R and CF-R groups, compared with the CF group. Sedentary time decreased and time spent in light-to-moderate or vigorous activity increased in all groups over time. Rehabilitation was significantly associated with greater time spent in light-to-moderate activity, regardless of diet.
CONCLUSIONS AND CLINICAL RELEVANCE Feeding the TF and providing physical rehabilitation during the first 6 months after TPLO were associated with improvements in some indices of clinical outcome and function in dogs. Significant interactions between time and some outcome variables were observed, indicating further research is warranted.
Objective—To characterize historical, clinicopathologic, ultrasonographic, microbiological, surgical, and histopathologic features of bacterial cholecystitis and bactibilia in dogs and evaluate response to treatment and outcomes in these patients.
Design—Retrospective case-control study.
Animals—40 client-owned dogs (10 with bacterial cholecystitis on histologic analysis or bactibilia on cytologic examination [case dogs] and 30 without bactibilia [controls]) evaluated at a veterinary teaching hospital between 2010 and 2014.
Procedures—Signalment, history, clinicopathologic findings, ultrasonographic features, microbiological results, surgical findings, histopathologic changes, treatments, and outcomes of case dogs were derived from medical records and summarized. Demographic and clinicopathologic data and ultrasonographic findings were compared between case and control dogs. Relationships among prior antimicrobial treatment, sediment formation in the gallbladder, presence of immobile biliary sludge, and presence of bactibilia or bacterial cholecystitis were assessed.
Results—No finding was pathognomonic for bactibilia or bacterial cholecystitis in dogs. Case dogs were significantly more likely to have immobile biliary sludge and had a greater degree of biliary sediment formation than did control dogs. All case dogs for which gallbladders were examined histologically (6/6) had bacterial cholecystitis. Five of 10 case dogs were Dachshunds. Medical or surgical treatment resulted in good outcomes.
Conclusions and Clinical Relevance—Bactibilia and bacterial cholecystitis were important differential diagnoses in dogs with signs referable to biliary tract disease. Dachshunds were overrepresented, which may suggest a breed predisposition. Cytologic evaluation of bile should be considered in the routine assessment of dogs with hepatobiliary disease if immobile biliary sludge is present. (J Am Vet Med Assoc 2015;246:982–989)
Objective—To purify and partially characterize various
isoforms of canine pepsinogen (PG) from gastric
Sample Population—Stomachs obtained from 6
Procedure—Mucosa was scraped from canine stomachs,
and a crude mucosal extract was prepared and
further purified by use of weak anion-exchange chromatography,
hydroxyapatite chromatography, sizeexclusion
chromatography, and strong anionexchange
chromatography. Pepsinogens were characterized
by estimation of molecular weights, estimation
of their isoelectric points (IEPs), and N-terminal
amino acid sequencing.
Results—Two different groups of canine PG were
identified after the final strong anion-exchange chromatography:
PG A and PG B. Pepsinogens differed in
their molecular weights and IEP. Pepsinogen B
appeared to be a dimer with a molecular weight of
approximately 34,100 and an IEP of 4.9. Pepsinogen
A separated into several isoforms. Molecular weights
for the various isoforms of PG A ranged from 34,200
to 42,100, and their IEPs ranged from 4.0 to < 3.0. The
N-terminal amino acid sequence for the first 25 amino
acid residues for PG A and B had good homology with
the amino acid sequences for these proteins in other
Conclusions and Clinical Relevance—Canine PG B
and several isoforms of canine PG A have been purified.
Availability of these PGs will facilitate development
of immunoassays to measure PG in canine
serum as a potential diagnostic marker for gastric disorders
in dogs. (Am J Vet Res 2002;63:1585–1590)
Objective—To develop and validate an ELISA for
measurement of serum canine pepsinogen A (cPG A)
as a diagnostic marker of gastric disorders in dogs
and to measure serum cPG A in healthy dogs after
food deprivation and after feeding.
Sample Population—Sera from 72 healthy dogs.
Procedure—A sandwich ELISA was developed and
validated. The reference range for serum concentrations
of cPG A was determined in 64 healthy dogs.
Postprandial changes in serum concentrations of cPG
A were evaluated in 8 healthy dogs.
Results—Assay sensitivity was 18 µg/L, and the maximum
detectable concentration was 1,080 µg/L. The
observed-to-expected ratio (O:E) for 3 serial dilutions
of 3 serum samples ranged from 69.3 to 104.1%. The
O:E for 3 serum samples spiked with 8 concentrations
of cPG A ranged from 58.8 to 120.4%.
Coefficients of variation for intra- and interassay variability
of 3 serum samples ranged from 7.6 to 11.9%
and from 10.1 to 13.1%, respectively. Mean ± SD
serum concentration of cPG A in healthy dogs was
63.8 ± 31.0 µg/L and the reference range was 18 to
129 µg/L. Significant increases in serum concentrations
of cPG A were observed between 1 and 7 hours
Conclusions and Clinical Relevance—The ELISA for
measuring cPG A was sufficiently sensitive, linear,
accurate, precise, and reproducible for clinical use.
Serum concentrations of cPG A increase substantially
after feeding, which should be taken into account
when conducting clinical studies. (Am J Vet Res 2003;64:1146–1150)
OBJECTIVE To determine the effects of an omega-3 fatty acid and protein–enriched diet, physical rehabilitation, or both on radiographic findings and markers of synovial inflammation in dogs following tibial plateau leveling osteotomy and arthroscopic surgery for treatment of cranial cruciate ligament disease.
DESIGN Randomized, prospective clinical trial.
ANIMALS 48 dogs with unilateral cranial cruciate ligament disease.
PROCEDURES Dogs were randomly assigned to receive a dry omega-3 fatty acid and protein–enriched dog food formulated to support joint health (test food [TF]), a dry food formulated for adult canine maintenance (control food [CF]), TF plus rehabilitation, or CF plus rehabilitation after surgery. Synovial fluid prostaglandin (PG) E2 and interleukin-1β concentrations, radiographic osteoarthritis scores, osteotomy site healing, and patellar ligament thickness were assessed at predetermined time points up to 6 months after surgery.
RESULTS Dogs that received CF had significantly higher PGE2 concentrations over time following surgery than did dogs that received TF, regardless of rehabilitation status. Synovial fluid interleukin-1β concentrations did not change over time in any groups. Diet and rehabilitation were both associated with osteoarthritis scores, with significantly lower scores over time for dogs that received TF versus CF and for dogs that underwent rehabilitation versus those that did not. Proportions of dogs with complete osteotomy healing 8 and 24 weeks after surgery were significantly lower for dogs that received TF than for dogs that received CF, regardless of rehabilitation status.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that feeding the TF can result in lower synovial fluid PGE2 concentrations and that both the TF and rehabilitation can reduce progression of osteoarthritis in the 6 months following tibial plateau leveling osteotomy; clinical relevance of slower osteotomy healing in dogs fed the TF was unclear.