OBJECTIVE To determine whether dual-energy CT (DECT) could accurately differentiate the composition of common canine uroliths in a phantom model.
SAMPLE 30 canine uroliths with pure compositions.
PROCEDURES Each urolith was composed of ≥ 70% struvite (n = 10), urate (8), cystine (5), calcium oxalate (4), or brushite (3) as determined by standard laboratory methods performed at the Canadian Veterinary Urolith Centre. Uroliths were suspended in an agar phantom, and DECT was performed at low (80 kV) and high (140 kV) energies. The ability of low- and high-energy CT numbers, DECT number, and DECT ratio to distinguish uroliths on the basis of composition was assessed with multivariate ANOVA.
RESULTS No single DECT measure differentiated all urolith types. The DECT ratio differentiated urate uroliths from all other types of uroliths. The DECT and low-energy CT numbers were able to differentiate between 8 and 7 pairs of urolith types, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that DECT was unable to differentiate common types of canine uroliths in an in vitro model; therefore, it is unlikely to be clinically useful for determining urolith composition in vivo. Given that the primary reasons for determining urolith composition in vivo are to predict response to shock wave lithotripsy and develop a treatment plan, future research should focus on the correlation between DECT measurements and urolith fragility rather than urolith composition.
Objective—To assess whether the risk of development
of hypothyroidism after treatment with iodine
131 (131I) was associated with the pattern of sodium
pertechnetate Tc 99m activity in the thyroid gland
detected via scintigraphy before treatment in cats
Procedure—Medical records of cats with hyperthyroidism
that had been treated with 131I (from 1990 to
2002) and had undergone scintigraphy of the thyroid
gland before treatment were reviewed; data regarding
signalment, scintigraphic findings (classified as
unilateral, bilateral-asymmetric, bilateral-symmetric,
or multifocal patterns), serum total thyroxine (T4) concentrations
before treatment and prior to hospital discharge,
and 131I treatment were collected. A questionnaire
was sent to each referring veterinarian to obtain
additional data including whether the cats subsequently
developed hypothyroidism (defined as serum
total T4 concentration less than the lower reference
limit ≥ 3 months after treatment).
Results—50 of 165 (30.3%) 131I-treated cats developed
hypothyroidism. Hypothyroidism developed in 39
of 109 cats with bilateral, 10 of 50 cats with unilateral,
and 1 of 6 cats with multifocal scintigraphic patterns of
their thyroid glands. Cats with a bilateral scintigraphic
pattern were approximately 2 times as likely to develop
hypothyroidism after 131I treatment than were cats
with a unilateral scintigraphic pattern (hazard ratio, 2.1;
95% confidence interval, 1.04 to 4.2).
Conclusions and Clinical Relevance—Cats with
hyperthyroidism that have a bilateral scintigraphic pattern
in the thyroid gland before 131I treatment appear to
have a significantly higher risk of subsequently developing
hypothyroidism, compared with cats with a unilateral
scintigraphic pattern. (J Am Vet Med Assoc
Objective—To develop and determine the feasibility of a novel minimally invasive technique for percutaneous catheterization and embolization of the thoracic duct (PCETD) in dogs and to determine thoricic duct TD pressure at rest and during short-term balloon occlusion of the cranial vena cava (CrVC).
Animals—Fifteen 7- to 11-month-old healthy mixed-breed dogs.
Procedures—Efferent intestinal lymphangiography was performed, and the cisterna chyli was punctured with a trochar needle percutaneously under fluoroscopic guidance. When access was successful, a guide wire was directed into the TD through the needle and a vascular access sheath was advanced over the guide wire. Thoracic duct pressure was measured at rest and during acute balloon occlusion of the CrVC. The TD was then embolized cranial to the diaphragm with a combination of microcoils and cyanoacrylate or ethylene vinyl alcohol.
Results—Successful puncture of the cisterna chyli with advancement of a wire into the TD was possible in 9 of 15 dogs, but successful catheterization was possible in only 5 of 9 dogs. Acute balloon occlusion of the CrVC led to a substantial TD pressure increase in 4 of 4 dogs, and embolization of the TD was successful in 4 of 4 dogs.
Conclusions and Clinical Relevance—PCETD can successfully be performed in healthy dogs; however, this minimally invasive technique cannot currently be recommended for routine treatment of chylothorax, in part because of the technically demanding nature of the procedure. An increase in jugular venous pressure led to an increase in TD pressure, potentially predisposing some dogs to developing chylothorax.
Objective—To determine the effectiveness and safety of 2 sedative-analgesic protocols to facilitate assisted ventilation in healthy dogs.
Animals—12 healthy dogs.
Procedures—Dogs were randomly assigned to 2 groups. Mean dosages for protocol 1 were diazepam (0.5 mg/kg/h [n = 3 dogs]) or midazolam (0.5 mg/kg/h ), morphine (0.6 mg/kg/h ), and medetomidine (1.0 μg/kg/h ). Mean dosages for protocol 2 were diazepam (0.5 mg/kg/h [n = 3]) or midazolam (0.5 mg/kg/h ), fentanyl (18 μg/kg/h ), and propofol (2.5 mg/kg/h ). Each dog received the drugs for 24 consecutive hours. All dogs were mechanically ventilated with adjustments in minute volume to maintain normocapnia and normoxemia. Cardiorespiratory variables were recorded. A numeric comfort score was assigned hourly to assess efficacy. Mouth care, position change, and physiotherapy were performed every 6 hours. Urine output was measured every 4 hours.
Results—Use of both protocols maintained dogs within optimal comfort ranges > 85% of the time. The first dog in each group was excluded from the study. Significant decreases in heart rate, oxygen consumption, and oxygen extraction ratio were evident for protocol 1. Cardiac index values in ventilated dogs were lower than values reported for healthy unsedated dogs. Oxygen delivery, lactate concentration, and arterial base excess remained within reference ranges for both protocols.
Conclusions and Clinical Relevance—Use of both protocols was effective for facilitating mechanical ventilation. A reduction in cardiac index was detected for both protocols as a result of bradycardia. However, oxygen delivery and global tissue perfusion were not negatively affected.