Objective—To evaluate the efficacy and safety of
ultrasonographically guided radiofrequency heat ablation
of parathyroid masses in dogs with primary
Procedure—In all dogs, either 1 or 2 parathyroid
masses were evident ultrasonographically. Dogs
were anesthetized, and a 20-gauge over-the-needle
catheter was directed into the parathyroid mass via
ultrasonographic guidance. Radiofrequency heat
was applied to the stylet of the catheter until there
was sonographically apparent change to the entire
parenchyma of the mass. Serum total and ionized
calcium and parathyroid hormone concentrations
were monitored daily for 5 days after the ablation
procedure and again at 1, 2, and 3-month intervals,
if possible. Dogs were monitored for adverse
Results—One treatment was required in 6 dogs, 2
treatments were required in 2 dogs, and treatment
was unsuccessful in 3 dogs. Serum total and ionized
calcium concentrations were within reference ranges
within 2 days of the last procedure in all 8 successfully
treated dogs. Serum parathyroid hormone concentration
was decreased 24 hours after treatment in
all 8 dogs. Hypocalcemia developed in 5 of the 8 successfully
treated dogs, all of which required treatment.
One dog had a transient voice change. Other
adverse effects were not reported.
Conclusions and Clinical Relevance—Ultrasonographically
guided radiofrequency heat ablation of
parathyroid masses is a safe and effective alternative
to surgery in dogs with primary hyperparathyroidism.
(J Am Vet Med Assoc 2001;218:1106–1110)
Procedure—Results of dynamic portoscintigraphic
studies were reviewed by 4 radiologists without
knowledge of signalment, history, or medical profile.
Results were judged to be negative or positive on the
basis of the dynamic scan. Composite images were
formulated, and hand-drawn regions of interest were
determined for the heart and liver. Time-activity
curves were generated, time-zero points were selected,
curves were integrated during a 10-second interval,
and shunt fractions were calculated.
Results—Radiologists were in agreement regarding
positive versus negative results for 99 of 101 studies.
Interoperator variance in shunt fraction calculation
ranged from 0.4 to 59.6%. For 51 studies with positive
results, variance ranged from 2.5 to 59.6% (mean
± SD, 22.8 ± 14.5%); differences among reviewers
were significant. For 48 studies with negative results,
variance in shunt fraction ranged from 0.4 to 25.9%
(mean, 5.3 ± 5.8%); significant differences among
reviewers were not detected. Shunt fraction calculations
were not exactly reproducible among radiologists
in 94 and 100% of studies with negative or positive
Conclusions and Clinical Relevance—Results suggest
that shunt fraction values are not reproducible
among operators. Range in variability was greater in
studies with positive results. This factor may be of
particular clinical importance in reassessment of
patients after incomplete shunt ligation. (J Am Vet
Med Assoc 2001;218:1116–1119)
Objective—To determine the efficacy and safety of
percutaneous ethanol injection (PEI) for the treatment
of hyperthyroidism caused by bilateral hyperplastic
thyroid nodules in cats.
Procedure—Hyperthyroidism was diagnosed on the
basis of clinical signs and increased serum total thyroxine
(TT4) concentrations. The presence of 2 cervical
thyroid nodules was confirmed by use of ultrasonography
and technetium Tc 99m albumin thyroid scans.
After the death of 1 cat that received PEI in both thyroid
nodules at the same time, the protocol was
changed to injecting ethanol into 1 nodule at a time,
with at least 1 month between injections. Clinical
signs, serum TT4 concentrations, serum ionized calcium
concentrations, laryngeal function, findings on
ultrasonographic examinations of the ventral cervical
region, and results of thyroid scans were monitored.
Results—Serum TT4 concentrations transiently
decreased in all 6 cats (into the reference range in 5 of
6 cats) within 4 days of the first staged ethanol injection.
Each subsequent injection resulted in a transient
decrease in serum TT4 concentration. The longest period
of euthyroidism was 27 weeks. Adverse effects
included Horner's syndrome, dysphonia, and laryngeal
paralysis. One cat died of unrelated causes. One cat
underwent bilateral thyroidectomy, 2 cats were treated
with methimazole, and 2 cats that had increased
serum TT4 concentrations were not treated further,
because they remained clinically normal.
Conclusions and Clinical Relevance—Percutaneous
ethanol ablation of bilateral thyroid nodules as a treatment
for cats with hyperthyroidism is not recommended.
This treatment is not as efficacious as the
medical and surgical treatments presently used.
(J Am Vet Med Assoc 2001;218:1293–1297)