Parelaphostrongylus tenuis Cerebrospinal Nematodiasis in a Horse with Cervical Scoliosis and Meningomyelitis

There are reports of horses with acute onset acquired cervical scoliosis and cutaneous analgesia. The underlying dorsal gray column myelitis that produces these neurologic signs has been only presumptively attributed to migration of Parelaphostrongylus tenuis within the spinal cord. Despite previous confirmation brain by polymerase chain reaction testing, of P. tenuis within the brain of horses by polymerase chain reaction testing, genetic testing has failed to definitively identify the presence of this parasite in cases of equine myelitis. This case report provides molecular confirmation via polymerase chain reaction of P. tenuis within the cervical spinal cord of a horse with scoliosis and cutaneous analgesia.

Efficacy of Low-dose (2 millicurie) versus Standard-dose (4 millicurie) Radioiodine Treatment for Cats with Mild-to-Moderate Hyperthyroidism

Background

Radioiodine (¹³¹I) is effective treatment for hyperthyroidism in cats, but optimal dose to restore euthyroidism without inducing hypothyroidism is unclear. Treatment‐induced hypothyroidism can lead to azotemia and reduced duration of survival.

Objective

To compare efficacy and short‐term outcomes of low‐dose ¹³¹I versus higher, standard‐dose ¹³¹I as treatment for hyperthyroidism.

Animals

A total of 189 client‐owned cats undergoing ¹³¹I treatment for mild‐to‐moderate hyperthyroidism (serum T₄ ≥ 4.0 μg/dL and <13.0 μg/dL).

Methods

Prospective, nonrandomized, cohort study comparing treatment with either low‐dose (2 mCi, n = 150) or standard‐dose (4 mCi, n = 39) ¹³¹I. Serum T₄, thyroid‐stimulating hormone (TSH), and creatinine concentrations were measured after 1, 3, and 6 months to determine persistent hyperthyroidism, overt hypothyroidism (low T₄, high TSH), subclinical hypothyroidism (normal T₄, high TSH), and azotemia.

Results

There was no significant difference in prevalence of cats with persistent hyperthyroidism between standard‐ and low‐dose treatment groups at 3 (0% versus 5.3%; P = .34) and 6 (0% versus 3.3%; P = .51) months. Overt (18% versus 1%; P = .0005) or subclinical (46% versus 21%; P = .004) hypothyroidism was more common in cats at 6 months after standard‐dose ¹³¹I. No difference in incidence of azotemia existed between groups, but cats treated with standard‐dose ¹³¹I had higher creatinine concentrations (P < .05) and higher percent rises in creatinine (P < .0001).

Conclusions and Clinical Importance

Low‐dose ¹³¹I is safe and effective for cats with mild‐to‐moderate hyperthyroidism, as evidenced by a cure rate of >95% with reduced frequency of iatrogenic hypothyroidism and azotemia.

Adverse reactions in horses that underwent general anesthesia and cervical myelography

Background

The study was prompted by a perceived high prevalence of myelographic complications varying in severity and type, and attributed to the contrast material or the procedure.

Hypotheses

1. Any adverse reaction (AAR) is associated with a change in CSF volume induced either by removal of CSF or addition of contrast material. 2. AAR occurs more frequently in horses with higher premyelography neurologic grade. 3. Nonspecific hyperthermia is attenuated by anti‐inflammatory and osmotic agents.

Animals

Horses (n = 278) that underwent myelography between 2000 and 2012 at 5 institutions: A (87), B (68), C (65), D (46), and E (12).

Methods

Multi‐institutional, retrospective, observational cross‐sectional study.

Results

AAR were observed in 95/278 (34%) horses, were associated with longer general anesthesia time (P = .04) and higher contrast‐medium volume (P = .04); euthanasia because of AAR was performed in 5/278 (2%) horses. Adverse neurologic reactions were the most common type of complication observed occurring in 15/278 (5%) and 42/235 (18%) of horses in the intra‐ and postmyelography periods. A relationship between AAR and premyelography neurologic grade was not identified (P = .31). Nonspecific hyperthermia was observed in 25/235 (11%) horses; no relationship was observed with administration of anti‐inflammatory drugs and osmotic agents (P = .30).

Conclusions and clinical importance

The category of AAR occurred in one‐third of the horses generally was mild and self‐limiting. These reactions were associated with increased contrast‐medium volume and longer anesthesia time; but, no specific procedural recommendations could be made because of small odds ratios (OR) of <2 for each 1 mL increase in contrast material and for each 1 minute of additional anesthesia time.

Observer agreement study of cervical-vertebral ratios in horses

REASON FOR PERFORMING STUDY

Different examiners or the same examiner were observed at different times producing slightly different results when obtaining cervical-vertebral ratios. If the difference is substantial, then measurement variability would have an important impact of radiographic interpretation.

OBJECTIVE

To quantify agreement and repeatability of these measurements.

METHODS

An observer agreement study was performed using 75 horses. Measurements were made at C3-4 and C6-7 by a board-certified radiologist and an imaging resident. Intra- and interobserver agreement was quantified using Bland-Altman plots. Repeatability was assessed as the percentage of differences between duplicate measurements by the radiologist that were within ± 2 s.d. of the differences.

RESULTS

At C3-4, the limits of agreement for the intra-vertebral ratio were between -5 and 4% for the intra- and -5 and 6% for interobserver comparison. For the intervertebral ratio, they were between -9 and 8% for the intra- and -10 and 10% for interobserver comparison. At C6-7, the limits of agreement for the intra-vertebral ratio were between -6 and 5% for the intra- and -6 and 8% for interobserver comparison. For the intervertebral ratio, they were between -7 and 7% for the intra- and -6 and 13% for interobserver comparison. At C3-4, all measurements were 95% repeatable (differences typically ≤ 4% and always ≤ 8%) for the intra-vertebral ratio and 96% repeatable (differences typically ≤ 8% and always ≤ 11%) for the intervertebral ratio. At C6-7, all measurements were 98% repeatable (differences typically ≤ 6% and always ≤ 7%) for the intravertebral ratio and 92% repeatable (differences typically ≤ 6% and always ≤ 10%) for the intervertebral ratio.

CONCLUSIONS

Cervical-vertebral ratios typically varied by 5-10% within and between examiners.

POTENTIAL RELEVANCE

When using cervical-vertebral ratios in practice, the impact of measurement agreement should be factored into the interpretation of the test result because measurement variability may lead to misdiagnosis and limit the clinical usefulness of these tests.

Evaluation of decision criteria for detection of spinal cord compression based on cervical myelography in horses: 38 cases (1981-2001)

REASONS FOR PERFORMING STUDY

Different criteria have been described based on height reduction of the total myelographic contrast column and components of it as tests for compression of the spinal cord due to cervical stenotic myelopathy (CSM). Fifty percent height reduction of the dorsal myelographic column (DMC), <2 mm empiric height of the DMC and a 40% reduction of the ratio of stenosis calculated based on the height reduction of the entire dural diameter (DD) have been described as decision criteria for considering the test result positive. The reasons for selecting these decision criteria or their accuracies have rarely been reported.

OBJECTIVES

To evaluate the accuracy of diagnostic criteria based on reduced height of the total myelographic column and components of it for diagnosing extradural spinal cord compression using different decision criteria, and make recommendations for consistent myelographic interpretation in horses suspected of having CSM.

METHODS

Four measurements were obtained by 2 readers in a retrospective sample population of 38 horses in which both cervical myelography and histopathological examination of the cervical spinal cord were performed. The prevalence of CSM in the sample was 50%. At intervertebral sites, the minimum heights of the DD and DMC were measured. At intravertebral sites, the maximum heights of the entire DD and DMC were obtained. Percent height reductions of the DMC and DD were determined as the ratio of minimum intervertebral height to maximum intravertebral height within the next cranial vertebra. Histological examination was used as the gold standard for determining the actual site of spinal cord compression. Sensitivity and specificity for the diagnostic criteria were estimated at each site in neutral and flexed neck positions using several different decision criteria.

CONCLUSIONS

At C6-C7, in neutral or flexed neck position and using 20% reduction of DD, the test was highly sensitive and specific for CSM. At other sites, reduced height of the myelographic column generally was not accurate for diagnosing extradural spinal cord compression. Using 20% reduction of DD in neutral position at the mid-cervical sites, the test had only low sensitivity and high specificity. Flexion of the neck appeared to increase detection of spinal cord compression in the mid-cervical region, but also substantially increased the frequency of false-positive diagnoses.

POTENTIAL RELEVANCE

By using the reported sensitivity and specificity estimates, readers may decide on a decision criterion for diagnosis of extradural spinal cord compression due to CSM. However, in planning a surgical correction, it is difficult to define a decision criterion that combines acceptable sensitivity and specificity, especially at the mid-cervical sites.

Computed tomography dacryocystography evaluation of the nasolacrimal apparatus

Computed tomography-dacryocystography (CT-DCG) was used to evaluate the nasolacrimal system in four patients (three dogs and one horse) that were admitted for evaluation of chronic epiphora, facial swelling, or facial trauma. The four patients are reviewed and the technique for performing CT-DCG is described. Additionally, the indications for this procedure are discussed. CT-DCG is advantageous because cross-sectional imaging provides superior resolution of the nasolacrimal apparatus and the relatively long, small-diameter, bony nasolacrimal canal in most veterinary patients.

Influence of patient positioning on sensitivity of mesenteric portography for detecting an anomalous portosystemic blood vessel in dogs: 34 cases (1997-2000)

OBJECTIVE

To determine whether sensitivity of detecting an anomalous portosystemic blood vessel during operative mesenteric portography varied with patient positioning.

DESIGN

Retrospective study.

ANIMALS

34 dogs with a portosystemic shunt diagnosed via scintigraphy or surgery.

PROCEDURE

Portograms were evaluated for a portosystemic blood vessel. Sensitivity was calculated from results obtained with dogs in left lateral, right lateral, and dorsal recumbency and from results obtained with dogs in 2 or 3 positions. Differences in sensitivity among positions and between 2 examiners were evaluated.

RESULTS

Sensitivity was 85, 91, and 100% in dorsal, right lateral, and left lateral recumbency, respectively. Sensitivity was lower in dorsal recumbency than in left lateral recumbency, although differences were not significant. There was no significant difference between sensitivity of results obtained in dorsal and right lateral recumbency or right lateral and left lateral recumbency. Sensitivity for combined right lateral and dorsal positions was 97%, which was better than that in dorsal recumbency alone, although the difference was not significant. Because sensitivity in left lateral recumbency was 100%, there was no need to evaluate the improvement obtained by combining the result of this position with the results of other positions.

CONCLUSION AND CLINICAL RELEVANCE

Results of mesenteric portography varied with patient positioning. The optimal position varied among patients but left lateral recumbency may be better and dorsal recumbency worse. Sensitivity may be improved by performing the test with the patient in orthogonal recumbent positions.

Myelographic artifacts

During myelography, injection of contrast outside the subarachnoid space can lead to false-negative or false-positive studies by not contrasting lesions or creating spurious signs. The production of high-quality myelograms and successful interpretation depend on knowledge of meningeal anatomy and the appearance of contrast material when injected between different meningeal layers. Opacification of the subdural space is a recently described technical complication in veterinary medicine, and increasingly is being recognized as a common problem during myelography. The purpose of this article is to describe the appearance of the different columns of contrast material that can be produced during myelography and to correlate these findings to the relevant anatomy, especially the subdural space.

Gallbladder perforation associated with cholelithiasis and cholecystitis in a dog

A four-year-old female Japanese akita was admitted with icterus, ascites and chronically elevated serum bilirubin and liver enzymes. Abdominal ultrasonography revealed a diffusely thickened, hyperechoic gallbladder wall with a focal defect, hepatic lymphadenopathy and a large volume of anechoic fluid within the peritoneal space. Diagnosis of biliary tract rupture with bile peritonitis was based on the findings of bile and suppurative exudate in peritoneal aspirates. A perforated gallbladder and cholelithiasis were found on exploratory celiotomy, while histopathology revealed chronic suppurative cholecystitis. The dog recovered uneventfully after cholecystectomy. Although rare, the triad of cholelithiasis, cholecystitis and gallbladder perforation should be considered after detection of one of these conditions.

Effects of acepromazine and butorphanol on positive-contrast upper gastrointestinal tract examination in dogs

OBJECTIVE

To determine whether acepromazine (ACE) and butorphanol (BUT) combination can be used for restraint of dogs during positive-contrast upper gastrointestinal tract (UGIT) examination.

ANIMALS

6 healthy dogs.

PROCEDURE

In a randomized crossover design study, weekly UGIT examinations were performed on each dog for 5 weeks after administration of normal saline solution (0.5 ml), xylazine (1.0 mg/kg of body weight), or a combination of ACE (0.1 mg/kg) and 1 of 3 doses of BUT (0.05, 0.2, 1.0 mg/kg). Gastrointestinal tract emptying time, GI motility, pulse, respiratory rate, and quality of restraint were assessed.

RESULTS

Total gastric emptying time was significantly prolonged by use of an ACE and BUT (0.05 mg/kg) combination. Xylazine and higher dosages of BUT significantly prolonged gastric and intestinal emptying times. All anesthetic protocols significantly decreased motility and facilitated nonmanual restraint. Xylazine and BUT (1.0 mg/kg) significantly decreased pulse and respiratory rate.

CONCLUSION

The ACE and BUT combination prolonged GI tract emptying times, decreased GI motility, and facilitated nonmanual restraint for duration of the examination. Although GI motility was decreased and total gastric emptying time was prolonged, administration of ACE (0.1 mg/kg) plus BUT (0.05 mg/kg) allowed morphologic examination of the GI tract within 5 hours. Xylazine prolonged GI tract emptying, decreased GI motility, and provided good to excellent initial restraint. Clinical Relevance-The ACE and BUT combination prohibits functional examination of the GI tract; however, morphologic examination is possible when low dosages of BUT (0.05 mg/kg) are used.

Results of double-contrast cystography in cats with idiopathic cystitis: 45 cases (1993-1995)

OBJECTIVE

To determine results of double-contrast cystography in cats with idiopathic cystitis.

DESIGN

Retrospective study.

ANIMALS

45 cats with clinical signs of nonobstructive lower urinary tract disease for which an underlying cause could not be determined.

PROCEDURE

Medical records and double-contrast cystograms performed initially and during 6- and 12-month reevaluations were reviewed.

RESULTS

105 cystograms were reviewed. Fifteen (33%) cats had abnormalities evident on cystograms obtained at the time of initial examination. Of these, only 1 had abnormalities 6 and 12 months later. Thirty cats did not have abnormalities evident on cystograms obtained at the time of initial examination. Of these, 1 had abnormalities on a cystogram performed 6 months later and another had abnormalities on a cystogram performed 12 months later. Abnormalities evident on cystograms included focal thickening of the bladder wall (n = 11), diffuse thickening of the bladder wall (6), irregularities of the bladder mucosa (10), decreased opacity of the bladder wall (3), increased opacity of the bladder mucosa (3), filling defects (4), contrast medium in unexpected locations (3), and altered ureteral opacity (15).

CLINICAL IMPLICATIONS

Results suggested that a large percentage of cats with idiopathic cystitis do not have cystographic abnormalities when initially examined but that abnormalities may be apparent during follow-up evaluations. In addition, a smaller percentage of cats with idiopathic cystitis may have nonspecific cystographic signs of cystitis or hemorrhage. Leakage of contrast medium into the peritoneal space during cystography does not necessarily require surgical management.

Prevalence of gallbladder sludge in dogs as assessed by ultrasonography

Ultrasonography of the gallbladder was performed in 3 groups of dogs: 30 clinically healthy dogs, 50 dogs with hepatobiliary disease, and 50 dogs with diseases other than hepatobiliary disease. The gallbladder was evaluated for the presence of sludge (echogenic material without acoustic shadowing). Maximal gallbladder length, width, height, and area were measured as well as the gallbladder wall thickness. The relative sludge area was calculated as the ratio of sludge area over gallbladder area on longitudinal images. No significant difference was found in the prevalence of gallbladder sludge among healthy dogs (53%), dogs with hepatobiliary diseases (62%), and dogs with other diseases (48%). The mean age of dogs with sludge was higher than the mean age of dogs without sludge in dogs with hepatobiliary disease and dogs with other diseases (p < 0.05). The mean relative sludge area did not differ significantly among the 3 groups. A trend to larger gallbladder dimensions in dogs with sludge compared to dogs without sludge was detected within the 3 groups. The gallbladder wall thickness was not different between dogs with and without sludge within the 3 groups. However, the gallbladder wall was more frequently isoechoic than hyperechoic to the liver in dogs with sludge than in dogs without sludge. The results of this study indicate that gallbladder sludge, in dogs, is not particularly associated with hepatobiliary disease and should be considered an incidental finding.

Results of retrograde urethrography in cats with idiopathic, nonobstructive lower urinary tract disease and their association with pathogenesis: 53 cases (1993-1995)

OBJECTIVE

To describe results of retrograde urethrography in cats with idiopathic, nonobstructive lower urinary tract disease (LUTD), to review the normal anatomy of the feline urethra, and to relate anatomy observed radiographically to the pathogenesis and diagnosis of LUTD in cats.

DESIGN

Retrospective case series and anatomic study.

ANIMALS

53 cats with signs of nonobstructive LUTD for which an underlying cause could not be determined. Results for these cats were compared with those for 6 healthy female cats undergoing urethrocystoscopy for another study and 6 male cats without a history of LUTD undergoing necropsy examination.

PROCEDURE

Medical records, results of positive-contrast retrograde urethrography (cats with idiopathic, nonobstructive LUTD) and urethrocystoscopy (healthy female cats), and necropsy findings (healthy male cats) were reviewed.

RESULTS

Abnormalities were not detected during urethrocystoscopy, dissection, or urethrography. Previously, the urethra in male cats has been described simply as a long tube that tapers caudally, and the only structures consistently differentiated by radiography have been pelvic and penile parts. In this study, the seminal colliculus, isthmus of the urethra, preprostatic part of the urethra, and urethral crest were consistently observed in male cats in addition to pelvic and penile parts. The urethral crest also was observed in the comparatively simple female urethra.

CLINICAL IMPLICATIONS

During retrograde urethrography in cats, prior distention of the bladder with positive-contrast medium may obscure radiographic signs associated with normal anatomic structures. Knowledge of urethral anatomy and radiographic signs associated with idiopathic, nonobstructive LUTD in cats should improve understanding of the pathogenesis and diagnosis of this disease.

Side lobes and grating lobes artifacts in ultrasound imaging

Side lobes and grating lobes are both unwanted parts of the ultrasound beam emitted off axis that produce image artifacts due to error in positioning the returning echo. The purpose of this study was to reproduce artifacts associated with side lobes and grating lobes in vitro using different transducer types and recognize these artifacts in vivo. A phantom, composed of a water bath, a metallic wire, and a wooden tongue depressor, was imaged using a linear array, a curved linear a vector array, and a sector mechanical transducer. When imaging the metallic wire in a transverse plane, an echogenic artifact was constantly seen on each side of the wire, with a shape and intensity variable with the transducer type. The artifact was curvilinear and concave (linear and curved linear arrays), or curvilinear and convex (vector array and the mechanical transducer). When the tongue depressor was imaged in a longitudinal plane, the artifact was a straight line (linear array), a curved convex line (curved array), a series of convex curvilinear echo (vector array) or a small convex curvilinear echo (mechanical transducer). In vivo situations similar to the phantom experiment were investigated using clinical patients. Artifacts produced in vitro were recognized in vivo when a highly reflective object (urinary bladder wall) was imaged adjacent to an anechoic region (urine). These artifacts corresponded to the principle of secondary ultrasound lobes, and were therefore interpreted as such.

The effect of patient positioning on mural filling defects during double contrast cystography

Different radiographic findings may be observed during double contrast cystography due to patient positioning affecting the distribution of positive and negative contrast media. A mass lesion was created in the urinary bladder of a canine cadaver to allow evaluation of the effect of patient positioning on the appearance of a mass during double contrast cystography. The mass appeared as a filling defect only on those views where positive contrast medium surrounded the mass. Otherwise, the mass appeared as a summation. Additionally, a patient is described illustrating the effect of patient positioning on detecting mural filling defects during double contrast cystography.

Subdural injection of contrast medium during cervical myelography

Three patients (1 dog, 2 horses) are described where myelography was complicated, purportedly by injection of contrast medium into the meninges superficial to the subarachnoid space. Contrast medium injected in this location in a cadaver tended to accumulate dorsally within the vertebral canal, deep to the dura mater but superficial to the subarachnoid space. The ventral margin of the pooled contrast medium had a wavy or undulating margin and the dorsal margin was smooth. Pooled contrast medium was believed to be sequestered within the structurally weak dural border cell layer between the dura mater and arachnoid membrane, or the so-called subdural space.

Multifocal polyostotic aneurysmal bone cysts in a llama

A 3.3-year-old 125-kg castrated male llama was evaluated because of acute non-weight-bearing lameness on the left hind limb. Physical examination revealed crepitus in the midportion of the femur. On radiographs, a comminuted middiaphyseal fracture was seen. There was also a region of bone lysis with cortical thinning and expansion in the distal metaphysis and epiphysis of the left femur. Multiple small circular lesions were observed in the proximal metaphysis of the left femur, and the proximal portion of the left tibia appeared irregular. The owner elected to pursue treatment, and the fracture was repaired with 2 compression plates. Multiple bone biopsy specimens were obtained and submitted for bacterial culture and histologic examination. Cultures yielded neither bacteria nor fungi. Histologic examination revealed fibrous connective tissue, normal appearing cortical bone, and an absence of medullary structures. The llama was maintained in a hind-limb sling for 14 days after surgery, at which time follow-up radiography revealed a comminuted fracture of the proximal portion of the femur. The llama was euthanatized, and multifocal polyostotic aneurysmal bone cysts were found in the proximal and distal metaphyses of the left femur and tibia. Cysts were lined by fibroblasts or endothelial-like cells.

Clinical evaluation of cats with nonobstructive urinary tract diseases

OBJECTIVE

To identify the underlying cause of clinical signs in cats with nonobstructive diseases of the bladder and urethra.

DESIGN

Prospective case series.

SAMPLE POPULATION

109 cats examined by the urology service of The Ohio State University's veterinary teaching hospital because of stranguria, hematuria, pollakiuria, or urination in inappropriate locations.

PROCEDURE

History was obtained and a CBC, serum biochemical analyses, serologic tests for FeLV and feline immunodeficiency virus, urinalysis, bacterial culture of urine, and contrast radiography or urethrocystoscopy (females only) were performed.

RESULTS

16 cats had cystic calculi: 8 had struvite uroliths, 7 had calcium oxalate uroliths, and 1 had a urolith of unknown composition in conjunction with an anatomic defect. Anatomic defects, including diverticulae, urethral strictures, and a malpositioned urethra, were identified in 12 cats. A urinary tract infection was identified in 1 cat, and neoplasia was diagnosed in 2. One of the cats with neoplasia also had a struvite urolith. The remaining 80 cats did not have an anatomic defect, urolith, or tumor. Ten of these cats also did not have radiographic or cystoscopic abnormalities and were presumed to have a behavioral disorder. The remaining 70 cats had radiographic or cystoscopic abnormalities, and idiopathic cystitis was diagnosed. In 14 of the cats with idiopathic cystitis, results of a urinalysis were normal. Cats with idiopathic cystitis were significantly more likely to eat dry food exclusively (59%) than were cats in the general population (19%).

CLINICAL IMPLICATIONS

Results suggest that idiopathic cystitis occurs commonly in cats with stranguria, hematuria, pollakiuria, or inappropriate elimination and is associated with consumption of dry foods. Contrast radiography or cystoscopy is necessary for differentiating idiopathic cystitis from behavioral disorders in some cats.