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Abstract

Objective—To determine effects of regional variation, interobserver variability, and vessel selection on quantitative vascular variables derived by dynamic contrast-enhanced computed tomography (DCE-CT) of the brain of clinically normal dogs.

Animals—14 adult dogs with no evidence of CNS dysfunction.

Procedures—Dogs were randomly assigned to 4 groups, and DCE-CT was performed at the level of the frontal lobe, rostral portion of the parietal-temporal lobes, caudal portions of the parietal-temporal lobes, or occipital lobe–cerebellum for groups 1 to 4, respectively. Cerebral blood flow (CBF), cerebral blood volume (CBV), and permeability in gray and white matter for both a large and small artery were calculated and compared. Values among 3 observers and 4 regions of the brain were calculated and compared.

Results—Significant interobserver variability was detected for CBF and permeability in white matter. Values calculated for large and small arteries were correlated for CBV and CBF but not for permeability. Overall mean ± SD for CBF, CBV, and permeability in gray matter was 53.5 ± 27.7 mL/min/100 g, 2.9 ± 1.4 mL/100 g, and 1.4 ± 2.2 mL/min/100 g, respectively. Mean for CBF, CBV, and permeability in white matter was 44.2 ± 28.5 mL/min/100 g, 2.5 ± 1.5 mL/100 g, and 0.9 ± 0.7 mL/min/100 g, respectively. Values did not differ significantly among brain regions.

Conclusions and Clinical Relevance—Significant regional variations were not detected for quantitative vascular variables in the brain of clinically normal dogs. However, interobserver variability and vessel selection have an important role in variable estimation.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize a genetic component to cricopharyngeal dysfunction (CD) in Golden Retrievers.

Animals—117 dogs.

Procedure—The CD phenotype was determined by videofluoroscopy, and dogs were classified as affected if the upper esophageal sphincter (UES) did not open, if there were morphologic abnormalities of the UES, or if opening of the UES was delayed for ≥ 6 videofluoroscopic frames (0.2 seconds) after closure of the epiglottis. All survey radiographic and videofluoroscopic studies were reviewed by the same radiologist.

Results—Of the 117 dogs (47 males and 70 females) with a CD phenotype determined via videofluoroscopy, 21 dogs (18.0%) had abnormalities of the UES (affected). Of these 21 dogs, 9 were males (19.1% of all males) and 12 were females (17.1% of all females). The heritability of CD in a threshold model was estimated as 0.61, which established that CD could be passed from parent to offspring. Results of complex segregation analysis suggested that a single recessive allele of large effect contributed to the expression of this disease in Golden Retrievers.

Conclusions and Clinical Relevance—The determination that CD is inherited in Golden Retrievers is an important step in providing information for veterinarians attending dogs with this disorder. Breeders also require this information to make informed breeding decisions. ( Am J Vet Res 2004;65:344–349)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs and evaluate the relationships of thyroid gland size and volume with body weight and body surface area (BSA).

Animals—72 dogs of small (6 Toy and 6 Miniature Poodles), medium (12 Beagles), and large breeds (12 Akitas and 36 Golden Retrievers).

Procedure—Each dog's thyroid gland was examined ultrasonographically with a 10- to 5-MHz multifrequency linear-array transducer. Size, shape, echogenicity, and homogeneity of thyroid lobes were evaluated on longitudinal and transverse images. Thyroid lobe volume was estimated by use of the equation for an ellipsoid (π/6 [length × height × width]).

Results—Thyroid lobes appeared fusiform or elliptical on longitudinal images and triangular or round to oval on transverse images. In most dogs, thyroid lobes were hyperechoic or isoechoic, compared with surrounding musculature, and had a homogeneous echogenic pattern. Mean length, width, height, and volume of thyroid lobes were significantly greater in Akitas and Golden Retrievers, compared with findings in Beagles or Poodles; mean length, width, and height were significantly greater in Beagles, compared with findings in Poodles. Total thyroid gland volume correlated with body weight (r = 0.73) and BSA (r = 0.74).

Conclusions and Clinical Relevance—Among the dog breeds examined ultrasonographically, thyroid lobe size and volume were more variable than shape, echogenicity, and homogeneity. The correlation of thyroid gland volume with BSA suggests that size of the dog, rather than breed, should be considered when assessing thyroid glands ultrasonographically.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the efficacy and safety of ultrasonographically guided radiofrequency heat ablation of parathyroid masses in dogs with primary hyperparathyroidism.

Design—Clinical trial.

Animals—11 dogs.

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 effects.

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)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine outcome of and complications associated with cricopharyngeal myotomy or myectomy for treatment of cricopharyngeal dysphagia (CPD) in dogs

Design—Retrospective study.

Animals—14 dogs.

Procedure—Medical records of dogs with CPD that underwent cricopharyngeal myotomy or myectomy were examined. Follow-up information was obtained through telephone interviews with owners and referring veterinarians and clinical examinations when feasible.

Results—16 surgical procedures were performed on the 14 dogs. Dysphagia was completely resolved immediately after surgery in 1 dog, and clinical signs did not recur (follow-up time of 8 years); a second dog also had immediate complete resolution of dysphagia, but follow-up time was only 10 days. Three dogs had transient complete resolution with a mean time to recurrence of dysphagia of 12.3 weeks (range, 2 to 36 weeks). Three dogs had permanent partial resolution. Six dogs had no improvement after surgery. Eight of the 14 dogs were euthanatized because of problems related to CPD, including persistent dysphagia (n = 8) and aspiration pneumonia (5).

Conclusions and Clinical Relevance—The failure rate for dogs undergoing surgical treatment of CPD may be high, particularly if concurrent aspiration pneumonia or malnutrition is not addressed prior to surgery. For those dogs with concurrent diseases, more aggressive medical management, such as enteral tube feeding, may be warranted rather than surgery. In dogs with CPD complicated by other anatomic or functional conditions, such as myasthenia gravis, laryngeal paralysis, and esophageal stricture, surgery may also not be indicated. (J Am Vet Med Assoc 2003;223:1462–1468)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine efficacy and safety of percutaneous radiofrequency heat ablation for treatment of hyperthyroidism in cats.

Design—Prospective study.

Animals—9 cats.

Procedure—Hyperthyroidism was diagnosed via clinical signs and high serum total (TT4) and free thyroxine (fT4) concentrations. One or 2 hyperfunctional cervical thyroid nodules were detected by use of scintigraphy and ultrasonography. If cats had 1 abnormal thyroid lobe, heat ablation was performed on that lobe; if cats had 2 abnormal lobes, heat ablation was applied to the larger lobe. Overall, heat ablation was performed 14 times in the 9 cats. Clinical signs and serum TT4, fT4, and calcium concentrations were monitored daily for 2 days after the procedure, weekly for the first month, and then monthly. Laryngeal function was evaluated and cervical ultrasonography and thyroid scintigraphy were also performed. Monitoring continued for as long as 9 months after heat ablation if a cat became euthyroid or until an owner chose an alternative treatment because of recurrence of hyperthyroidism.

Results—Serum TT4 and fT4 concentrations transiently decreased after all 14 heat ablation procedures (≤ reference range after 10 of 14 treatments) within 2 days after the procedure. Cats were euthyroid for 0 to 18 months (mean, 4 months). Hyperthyroidism recurred in all cats. Adverse effects included transient Horner's syndrome (2 cats) and laryngeal paralysis without clinical signs (1 cat).

Conclusions and Clinical Relevance—Percutaneous heat ablation as a treatment for hyperthyroidism in cats is effective transiently but not permanently. (J Am Vet Med Assoc 2003;223:1602–1607)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine interoperator variance in shunt fraction calculation.

Design—Case series.

Sample Population—101 transrectal portoscintigraphic studies.

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 results, respectively.

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)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the incidence of adverse events within 24 hours after contrast-enhanced ultrasonography (CEUS) in dogs and cats and compare the risk of death within 24 hours after imaging for animals that underwent ultrasonography with and without injection of a contrast agent.

Design—Retrospective case-control study.

Animals—750 animals (411 case dogs, 238 control dogs, 77 case cats, and 24 control cats).

Procedures—At 11 institutions, medical records were reviewed of dogs and cats that had CEUS performed (cases) as were medical records of dogs and cats with clinical signs similar to those of case animals that had ultrasonography performed without injection of a contrast agent (controls). Information regarding signalment; preexisting disease; type, dose, and administration route of contrast agent used; immediate (within 1 hour after CEUS) and delayed (> 1 and ≤ 24 hours after CEUS) adverse events; and occurrence and cause of death (when available) was extracted from each medical record. Risk of death within 24 hours after ultrasonography was compared between case and control animals.

Results—Of the 411 case dogs, 3 had immediate adverse events (vomiting or syncope) and 1 had a delayed adverse event (vomiting). No adverse events were recorded for case cats. Twenty-three of 357 (6.4%) clinically ill case animals and 14 of 262 (5.3%) clinically ill control animals died within 24 hours after ultrasonography; risk of death did not differ between cases and controls.

Conclusions and Clinical Relevance—Results indicated that CEUS was safe in dogs and cats.

Full access
in Journal of the American Veterinary Medical Association