COMPARISON OF DIGITAL RADIOGRAPHY,ULTRASONOGRAPHY, AND POSITIVE CONTRAST VAGINOURETHROGRAPHY FOR DETERMINING REPRODUCTIVE STATUS OF FEMALE CATS

It is not always possible to identify female cats that have undergone previous ovariohysterectomy based on physical examination alone. An easy, cost‐effective method for screening female cats for reproductive status would be helpful for avoiding unnecessary exploratory laparotomies. The purpose of this prospective study was to compare diagnostic sensitivities of digital radiography, ultrasonography, and positive contrast vaginourethrography for determining reproductive status in female cats. Sixty‐seven recently euthanized female cats of unknown medical history and reproductive status were randomly selected and included in the study. Digital abdominal radiography, digital abdominal radiography with compression, abdominal ultrasonography, and positive contrast vaginourethrography were performed in sequence by a board‐certified veterinary radiologist and a second‐year radiology resident. Immediately following diagnostic imaging procedures, necropsy was performed. Ultrasonography of the uterus had the highest sensitivity (86%) for determining reproductive status of all the imaging modalities tested. The specificity was 88%, and the positive predictive value and negative predictive value were 96% and 68%, respectively. The calculated sensitivities and specificities of other modalities were as follows: digital radiographs (28%, 100%), digital compression radiographs (58%, 100%), and vaginourethrography (32%, 100%). Based on McNemar's test statistic, there was a significant difference in the sensitivity of ultrasound compared to digital radiographs (P ≤ 0.05), compression radiographs (P ≤ 0.05), and vaginourethrogram (P ≤ 0.05). Findings from the current study indicated that ultrasonography is a sensitive diagnostic test for determining reproductive status in female cats. Although more readily available in private practice and shelters, digital radiography and vaginourethrography are not reliable predictors of reproductive status.     

RETROSPECTIVE ASSESSMENT OF COMPUTED TOMOGRAPHIC IMAGING OF FELINE SINONASAL DISEASE IN 62 CATS

Sixty-two cats with sinonasal disease were evaluated with computed tomography. Findings that may lead to a computed tomographic diagnosis of nasal neoplasia versus rhinitis included osteolysis of the paranasal bones, moderate to severe turbinate destruction, lysis of the nasal septum, the presence of a homogenous space occupying mass, and extension of the disease process into the orbit or facial soft tissues. These findings were not pathognomonic for neoplasia and may be associated with severe rhinitis; therefore, nasal biopsy was recommended. When compared with parallel radiographic studies, computed tomography was not more sensitive than radiographs at detecting the presence of nasal cavity abnormalities in cats with referable clinical signs but was more sensitive at localizing these changes and determining the extent of disease.     

EVALUATION OF IOHEXOL AS A GASTROINTESTINAL CONTRAST MEDIUM IN NORMAL CATS

The non-ionic, iodinated contrast medium, iohexol (240 mg I/ml) was evaluated as a gastrointestinal (GI) contrast medium in cats. Iohexol, both undiluted and diluted with tap water, was administered via a percutaneous endoscopically-placed gastrotomy (PEG) tube to 4 mature clinically normal cats. The dilution of contrast medium administered was 1:1, 1:2, and 1:3, and doses were 10 ml/kg and 5 ml/kg body weight. All combinations of dilution and dose of iohexol provided adequate visualization of the contrast medium column within the GI tract, and results were not significantly different than those observed using 30% w/v barium sulfate. Dehydration and diarrhea were not observed after contrast medium administration, but vomiting occurred within 15–30 minutes after administration of undiluted iohexol in all experimental cats. Renal opacification did not occur on exposures made through a 2 hour period, and dilution in transit was not apparent.     

QUANTITATIVE VIDEOFLUOROSCOPIC EVALUATION OF PHARYNGEAL FUNCTION IN THE DOG

Videofluoroscopic evaluation of both liquid barium and barium soaked kibble was performed in 11 adult, clinically normal dogs of varying breeds. Each examination was digitized and evaluated frame by frame to establish the normal timing sequence of the pharyngeal phase of swallowing. Closure of the epiglottis was considered the onset of swallowing. The time to each of the following events was recorded: (1) Maximum pharyngeal contraction, (2) Opening of the epiglottis, (3) Opening of the cranial esophageal sphincter, and (4) Closure of the cranial esophageal sphincter. These values were found to be consistent both intra and interpatient. Retrospective analysis of 3 videofluoroscopic examinations from dogs that met the subjective criteria defining cricopharyngeal achalasia was then performed. A statistically significant delay in the time to opening and closure of the cranial esophageal sphincter was found employing both liquid barium and barium soaked kibble in the dogs with cricopharyngeal achalasia.     

ULTRASONOGRAPHIC APPEARANCE OF SPLENIC DISEASE IN 101 CATS

The sonographic findings in 101 cats with splenic abnormalities are presented. Diagnosis was made by ultrasound-guided fine needle aspirate or fine-needle biopsy (n = 91), ultrasound-guided core biopsy (n = 1), surgical core biopsy (n = 1), or necropsy (n = 10). Two cats had more than one diagnostic procedure (fine needle aspirate and necropsy or core biopsy and necropsy). The splenic abnormalities included lymphosarcoma (n = 30), mast cell tumor (n = 27), extramedullary hematopoiesis and/or lymphoid hyperplasia (n = 27), epithelial tumors (n = 6), mesenchymal tumors (n = 4), malignant histiocytosis (n = 2), myeloproliferative disease (n = 2), pyogranulomatous inflammation (n = 2), erythroleukemia (n = 1), eosinophilic syndrome (n = 1), hematoma (n = 1), and granulomatous splenitis (n = 1). Three cats had more than one splenic abnormality (mast cell tumor and metastatic carcinoma, pyogranulomatous inflammation and lymphoid hyperplasia, histiocytic lymphosarcoma, and lymphoid hyperplasia). Pathognomonic changes were not seen for any of the diseases.     

RADIOGRAPHIC AND ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT ATRIAL SIZE IN 100 CATS WITH ACUTE LEFT‐SIDED CONGESTIVE HEART FAILURE

The aims of this study were to evaluate left atrial size in cats with acute left‐sided congestive heart failure. We hypothesized that left atrial size as determined by thoracic radiography can be normal in cats with acute left‐sided congestive heart failure. One hundred cats with acute left‐sided congestive heart failure in which thoracic radiography and echocardiography were performed within 12 h were identified. Left atrial size was evaluated using right lateral and ventrodorsal radiographs. Measurements were compared to two‐dimensional echocardiographic variables of left atrial size and left ventricular size. On echocardiography, left atrial enlargement was observed in 96% cats (subjective assessment) whereas maximum left atrial dimension was increased (>15.7 mm) in 93% cats. On radiographs left atrial enlargement (subjective assessment) was found in 48% (lateral view), 53% (ventrodorsal view), and 64% (any view) of cats whereas left atrial enlargement was absent in 36% of cats in both views. Agreement between both methods of left atrial size estimation was poor (Cohen's kappa 0.17). Receiver operating characteristic curve analysis identified a maximum echocardiographic left atrial dimension of approximately 20 mm as the best compromise (Youden index) between sensitivity and specificity in the prediction of radiographic left atrial enlargement. Left atrial enlargement as assessed by thoracic radiography may be absent in a clinically relevant number of cats with congestive heart failure. Therefore, normal left atrial size on thoracic radiographs does not rule out presence of left‐sided congestive heart failure in cats with clinical signs of respiratory distress.     

THE SONOGRAPHIC APPEARANCE OF INTESTINAL MUCOSAL FIBROSIS IN CATS

The medical records of 11 cats with full‐thickness intestinal biopsies and histopathologic confirmation of segmental mucosal fibrosis were reviewed. All cats received an abdominal ultrasonographic evaluation. The sonographic feature of a small intestinal mucosal hyperechoic band paralleling the submucosa was present in all cats. Other intestinal sonographic findings included wall thickening, and altered wall layering (increased mucosal echogenicity, thickened submucosa, and/or muscularis layer). None of the cats had complete loss of wall stratification. All cats had clinical signs related to the gastrointestinal (GI) tract at the time of presentation. Three of the 11 cats had palpably thickened small intestinal loops, 3/11 abdominal pain, and 2/11 abdominal fluid. Histopathologically, mucosal fibrosis was associated with inflammatory cell infiltrates in all cats. In those cats with histopathologic evidence of mural fibrosis, all cats had a visible hyperechoic band through several intestinal segments. We speculate that the hyperechoic mucosal band represents the zone of mucosal fibrosis. Independently and prospectively, we reviewed the clinical presentation of 35 cats having this visible hyperechoic mucosal band on ultrasound. Twenty‐four of these 35 cats had clinical signs related to the digestive system at the time of record. Our study suggests that the hyperechoic mucosal band represents fibrosis, and in presence of concurrent GI signs, further diagnostic tests may be warranted.     

LONG-TERM FOLLOW-UP OF HYPERTHYROID CATS TREATED WITH IODINE-131

A long-term follow-up study of hyperthyroid cats treated with iodine-131 was conducted at the Texas A&M University Veterinary Teaching Hospital. Between January 1985 and December 1990, 255 cats were treated. Basic demographic data, information on treatment, and diseases at the time of diagnosis were recorded. Two hundred and thirty seven cats had long-term follow-up data collected by telephone interviews with the referring veterinarian and/or the owner on outcome of therapy, diseases that developed during the follow-up period and survival. Risk for developing hyperthyroidism was highest for cats greater than 10 years of age. There was no breed predisposition. Neutered cats were slightly over-represented among the cases compared to intact animals. Eighty-five percent of treated cats became clinically normal and remained euthyroid for a median time of 17.5 months. Four percent remained hyperthyroid and 9% became hypothyroid, requiring thyroid hormone supplementation.     

IMAGING ASSESSMENT OF THE MODIFIED DOUBLE CONTRAST BARIUM ENEMA USING CARBOXYMETHYLCELLULOSE ON RADIOGRAPHY AND ULTRASONOGRAPHY IN DOGS

A modified double contrast barium enema using carboxymethylcellulose was evaluated in beagle dogs and compared with dogs receiving a conventional barium enema. The experimental group was divided into three groups (1, 2, and 3) and given 30 ml/kg of different volume ratios of a barium vs. carboxymethylcellulose mixture. Each group underwent sonography following radiography. The volume ratio of one part barium to three parts carboxymethylcellulose was judged to be the optimal mixture, resulting in a general distribution of contrast and bowel radiolucency on radiographs and adequate postradiography sonography. The modified barium enema using carboxymethylcellulose is useful for assessing the general morphology and mucosal layers of the colon simultaneously on radiographs and ultrasonographs.     

RADIOGRAPHIC DIAMETER OF THE COLON IN NORMAL AND CONSTIPATED CATS AND IN CATS WITH MEGACOLON

Radiographs of 50 cats with no history of gastrointestinal disease were evaluated to establish a normal reference range for radiographic diameter of the feline colon. Thirteen cats with constipation and 26 with megacolon were also evaluated and compared with the normal cats to characterize the accuracy of the reference range and to identify a cutoff to distinguish constipation from megacolon. A ratio of maximal diameter of the colon to L5 length was the most repeatable and accurate measurement. A ratio <1.28 is a strong indicator of a normal colon (sensitivity 96%, specificity 87%). A value >1.48 is a good indicator of megacolon (sensitivity 77%, specificity 85%).     

RESPONSE OF NINETEEN CATS WITH NASAL LYMPHOMA TO RADIATION THERAPY AND CHEMOTHERAPY

The records of 19 cats treated for stage I nasal lymphoma with radiation therapy and chemotherapy were reviewed to determine response to therapy, treatment outcome and possible prognostic indicators. All cats were treated with megavoltage radiation therapy to a total dose ranging from 22 to 48 Gy (median dose = 42 Gy). All cats were prescribed at least 6 months of multiagent chemotherapy. The median progression-free interval for all cats was 945 days (31 months). Two cats did not achieve clinical remission. Of 17 cats evaluable for relapse, 10 (58.8%) were progression free during the entire follow-up period. Four cats (23.5%) suffered local recurrence, while three (17.6%) experienced distant relapse. The median survival time was 955 days (31.4 months). The only variable found to have a significant negative impact on survival was destruction of the cribriform plate before therapy (P= 0.002). The long progression free and survival times reported here indicate that cats with stage I nasal lymphoma treated with aggressive local and systemic therapy can have a favorable outcome when compared with other anatomic forms of lymphoma. Despite strong clinical responses to the multimodality therapy used, the fact that three (17.6%) cats relapsed distantly supports the recommendation that treatment with radiation therapy alone is insufficient until further prospective studies can be performed.     

SONOGRAPHIC ASSESSMENT OF GALLBLADDER VOLUME IN NORMAL CATS

We quantified gallbladder volume in 30 clinically healthy, fasted, cats, using an ellipsoid formula. All cats had a complete blood count and serum chemistry profile performed. Fasting times before sonography ranged from 12 to 16 h. The median gallbladder volume was 2.42 ml, with a range of 0.84–4.50 ml. The mean gallbladder volume was 2.41 ml. This reference range will assist clinicians when evaluating cats with hepatobiliary disease or suspected extrahepatic biliary obstruction.     

ULTRASONOGRAPHIC APPEARANCE OF HISTOPLASMOSIS IDENTIFIED IN THE SPLEEN IN 15 CATS

Histoplasmosis is the second most common fungal infection reported in the cat. The disseminated form involving lung, liver, lymph nodes, spleen, and bone marrow is a frequent manifestation of the disease. Limited information is available in the literature regarding the ultrasonographic appearance of the spleen in cats with disseminated or splenic histoplasmosis. A retrospective review of splenic ultrasound images from 15 cats confirmed to have histoplasmosis by splenic aspirates was performed. Size, echotexture, echogenicity, margin appearance, presence of nodules, and the overall shape of the spleen were reported in each case. Splenomegaly was documented in all cases (15/15) and a hypoechoic appearance of the spleen was documented in 14/15 of cases. The spleen was diffusely and uniformly affected in 14/15 (six homogenous and eight with a subtle mottled appearance) and had discrete nodules in 1/15 cats. Histoplasmosis should be included in the differential list for an enlarged and hypoechoic spleen in cats with consistent clinical findings. Additionally, ultrasound guided splenic aspirate may be a useful method to obtain a cytology sample for diagnosis.     

MAGNETIC RESONANCE IMAGING FEATURES OF BRAIN STEM ABSCESSATION IN TWO CATS

Premortem magnetic resonance imaging (MRI) was performed in two cats with brain stem abscessation confirmed post mortem by histology and recovery of multiple bacterial species. The MRI features of the abscesses were distinctive and included a thick and marked enhancement of the abscess capsule and extension of the lesion from a tympanic bulla in one cat. A focal area of increased signal intensity was present on T2-weighted images. A circumscribed area of decreased signal intensity was surrounded by a ring of increased signal intensity on precontrast T1-weighted images. A center of decreased signal intensity with a thick, markedly enhanced abscess capsule was observed on post contrast T1-weighted images. These findings are compared to the current experimental and clinical literature of brain abscess. The underlying pathogenesis of MRI features is reviewed.     

RADIOGRAPHIC APPEARANCE OF BRONCHOALVEOLAR CARCINOMA IN NINE CATS

Thoracic radiographs of nine cats with confirmed bronchoalveolar carcinoma (BAC) were reviewed retrospectively. Radiographic appearance of BAC was divided into three categories: mixed bronchoalveolar pattern, ill-defined alveolar mass, or mass with cavitation. In addition to these radiographic signs, all nine cats had evidence of some form of bronchial disease. Cavitary lesions were the most common finding (n = 5). In addition, three cats in this category had diffuse bronchointerstitial opacity and one cat had focal peribronchial cuffing. Five cats had either a mixed bronchoalveolar pattern with bronchiectasis (n = 3) or an ill-defined alveolar mass with peribronchial cuffing (n = 2). One cat had both a mixed bronchoalveolar pattern and a cavitary mass. Each of these nine cats had some form of bronchial disease (bronchointerstitial pattern, peribronchial cuffing, or bronchiectasis), which aids in the radiographic diagnosis of bronchoalveolar carcinoma and may represent airway metastasis.     

RADIOGRAPHIC PATTERNS OF PULMONARY METASTASIS IN 25 CATS

Thoracic radiographs of 25 cats with pulmonary metastatic disease and confirmed primary tumors were reviewed retrospectively. Pulmonary patterns of metastasis were divided into three categories, described as well-defined interstitial nodules, ill-defined interstitial nodules or a diffuse pulmonary pattern. The latter consisted of an alveolar pattern with or without ill-defined pulmonary nodules and/or pleural effusion. More cats presented with pulmonary metastatic disease in the category of either ill-defined nodules (n = 10) or a diffuse pattern (n = 7). Within this group, the most commonly represented primary tumor was mammary gland adenocarcinoma.     

MAGNETIC RESONANCE IMAGING FEATURES OF INTRAVENTRICULAR EPENDYMOMAS IN Five CATS

Intraventricular ependymoma is a rare type of feline intracranial neoplasia and published information on magnetic resonance imaging (MRI) characteristics is currently lacking. The purpose of this retrospective case series study was to describe the clinical and MRI characteristics of histopathologically confirmed intraventricular ependymomas in a group of cats. Five cats met inclusion criteria. In relation to normal gray matter, ependymomas appeared hyperintense on T2W, T2W‐FLAIR, PD, and DW‐EPI images; isointense on ADC images; and had subtle to strong contrast enhancement. Some variability was seen on T2*GRE and on T1W images with masses being isointense to hyperintense. Four ependymomas were small and homogeneous, and one was centrally cavitated. All cats had obstructive hydrocephalus, transtentorial herniation, and foramen magnum herniation. Perilesional edema was identified in most cats but was questionable in one. Intraventricular ependymoma should be considered as a differential diagnosis for cats with this combination of MRI signs.     

ULTRASONOGRAPHIC OBSERVATION OF SECRETIN-INDUCED PANCREATIC DUCT DILATION IN HEALTHY CATS

Secretin is a polypeptide hormone that stimulates secretion of bicarbonate from the exocrine pancreas and, in healthy human subjects, causes transient pancreatic duct dilation observable sonographically. In humans with chronic pancreatitis, secretin administration fails to cause pancreatic duct dilation, theoretically due to the restrictive effects of periductal fibrosis. We characterized the effect of exogenous secretin administration on the width of the pancreatic duct in nine healthy domestic cats. Cats were given a commercially available secretin product (ChiRho Stim™) while the pancreatic duct was monitored sonographically. Mean pancreatic duct diameter increased from 0.77±0.33 to 1.42±0.40 mm after secretin administration ( P =0.0017). The mean percent increase in pancreatic duct diameter over basal diameter for all time points up to 15 min postsecretin administration was 101.9±58.8%. Applicability of this technique to diagnose chronic pancreatitis in cats will need to be investigated.     

CONTRAST ENHANCED SONOGRAPHIC ASSESSMENT OF FEEDING VESSELS AS A DISCRIMINATOR BETWEEN MALIGNANT VS. BENIGN FOCAL SPLENIC LESIONS

Contrast‐enhanced sonography was conducted in 17 confirmed focal splenic lesions (five malignant, 12 benign). Relative echogenicity changes were used for subjective interpretation of lesion perfusion. A rapid influx of contrast agent, resulting in an increased relative echogenicity of the lesion, followed by a rapid clearance of contrast agent was referred to as early washin/early washout. There were 6/12 benign, and 3/5 malignant lesions characterized by early washin/early washout. Therefore, sensitivity, specificity, and accuracy for this parameter in differentiating malignant from benign lesions was 60%, 50%, and 53%, respectively. There were 2/12 benign, and 2/5 malignant lesions with persistent hypoperfusion throughout all phases. Therefore, sensitivity, specificity, and accuracy for malignancy using this criterion were 40%, 83%, and 71%, respectively. However, none of the benign and all malignant lesions were characterized by tortuous and persistently visible feeding vessels. This suggests that interpretation of splenic lesions cannot be performed accurately on the basis of echogenicity or persistent hypoperfusion, but that assessment of vascular tortuosity may be helpful in discriminating between a malignant vs. benign focal splenic lesion.