Dominique G. Penninck

Live attenuated, multiply deleted simian immunodeficiency virus causes AIDS in infant and adult macaques.

A substantial risk in using live attenuated, multiply deleted viruses as vaccines against AIDS is their potential to induce AIDS. A mutant of the simian immunodeficiency virus (SIV) with large deletions in nef and vpr and in the negative regulatory element induced AIDS in six of eight infant macaques vaccinated orally or intravenously. Early signs of immune dysfunction were seen in the remaining two offspring. Prolonged follow–up of sixteen vaccinated adult macaques also showed resurgence of chronic viremia in four animals: two of these developed early signs of disease and one died of AIDS. We conclude that this multiply deleted SIV is pathogenic and that human AIDS vaccines built on similar prototypes may cause AIDS.

Correlation between coagulation profile findings and bleeding complications after ultrasound-guided biopsies: 434 cases (1993-1996).

Medical records of 434 consecutive dogs (n=310) and cats (n=124) that received coagulation studies prior to ultrasound-guided biopsy procedures between January 1993 and June 1996 were reviewed for bleeding complications. Minor complications occurred in 21.9% of cases. Major complications occurred in 6% of the cases. Significant bleeding complications were observed in thrombocytopenic cases (P=0.0001). Dogs with a prolonged one-stage prothrombin time (OSPT) (P=0.031) and cats with prolonged activated partial thromboplastin time (aPTT) (P=0.024) were more likely to have complications than patients with normal values. Adequate tissue for histopathological diagnosis was obtained in 96.3% of cases. The likelihood of complication was smaller when the liver was biopsied than when the kidney was biopsied (n=259; P=0.0327). Ultrasound-guided biopsy of intracavitary structures is an effective and relatively safe procedure, but delay of the procedure should be considered when thrombocytopenia is present in the patient.

COMPARISON BETWEEN CLINICAL, ULTRASOUND, CT, MRI, AND PATHOLOGY FINDINGS IN DOGS PRESENTED FOR SUSPECTED THYROID CARCINOMA

This study compares clinical, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and pathology findings in 16 prospectively, and seven retrospectively recruited dogs presented for suspected thyroid carcinoma. Of these, 17 were confirmed thyroid carcinoma, while six were initially misdiagnosed. These included four carotid body tumors, one para-esophageal abscess, and one undifferentiated squamous cell carcinoma. Thyroid carcinomas occurred in older dogs without evidence of sex predilection, and were more often unilateral. All were large, heterogeneous, moderately to strongly vascularized, and most commonly contained areas of dystrophic mineralization and/or fluid accumulations. On MRI, thyroid carcinomas appeared hyperintense compared to surrounding musculature in all imaging sequences used, while on CT they had a lower attenuation value than normal thyroid gland tissue. Histologically confirmed tumor capsule disruption with invasion of the surrounding structures was most commonly detected with MRI. Palpation was not an accurate predictor of locally invasive vs. well-encapsulated masses. Computed tomography had the highest specificity (100%) and MRI had the highest sensitivity (93%) in diagnosing thyroid carcinoma, while ultrasound had considerably lower results. We conclude that ultrasound is adequate for use as a screening tool for dogs with suspected thyroid carcinoma, but recommend either CT or MRI for preoperative diagnosis and staging.

Histochemical and Ultrastructural Characterization of Primary Cardiac Chondrosarcoma

A cardiac chondrosarcoma was found in the right atrium of a Golden Retriever dog. Macroscopically, the right atrial lumen was filled with a 6- X 12- X 8-mm white glossy mass, which was diffusely attached to the underling myocardium. The mass was composed of spindle-shaped mesenchymal neoplastic cells loosely packed in light basophilic matrix, with focal areas of tightly packed cells in linear formation similar to the pattern of a growth plate. Tumor cells were positive when stained for vimentin and neuron-specific enolase, and weakly positive for S-100 protein. Ultrastructurally, neoplastic cells had abundant, dilated rough endoplasmic reticulum, Golgi apparatus, bundles of intermediate fibers, and primitive intercellular junctions between adjacent tumor cells. Based on morphologic, ultrastructural, histochemical, and immunohistochemical characteristics, this tumor was diagnosed as a chondrosarcoma.

Portal Vein Thrombosis in Cats: 6 Cases (2001–2006)

BACKGROUND Portal vein thrombosis (PVT) in cats is sparsely reported. PURPOSE OF STUDY To evaluate the clinical signs and diseases associated with PVT in cats. ANIMALS 6 client-owned cats. METHODS Medical records for cats with a portal vein thrombus diagnosed on abdominal ultrasound or at necropsy were reviewed. Signalment, historical data, underlying disorders, clinical findings, clinicopathologic and histopathologic data, diagnostic imaging findings, treatment, and outcome were recorded. RESULTS All 6 cats identified with PVT also had hepatic disease. Evidence of a congenital portosystemic shunt was present in 3/6 cats. Two cats had primary or metastatic hepatic neoplasia. One cat had acute cholangitis, acute pancreatitis, and locally extensive acute centrilobular hepatic necrosis. Two cats were suspected to have acute thrombi and 4 cats had chronic thrombi. CONCLUSION AND CLINICAL SIGNIFICANCE PVT might be an important concurrent finding in cats with hepatic disease.

Safety and correlation of test results of combined ultrasound-guided fine-needle aspiration and needle core biopsy of the canine spleen.

The safety and diagnostic value of combined splenic fine-needle aspiration (FNA) and needle core biopsy (NCB) is unknown. Forty-one dogs with splenic lesions were studied prospectively. Safety was assessed in 38 dogs and no complications were encountered. Initially, clinical and anatomic pathologists reviewed each FNA and NCB sample, respectively, without knowledge of the others results. Diagnoses were categorized as neoplastic, benign, inflammatory, normal, or nondiagnostic. The level of agreement between sampling methods was categorized as complete, partial, disagreement, or not available. Test correlation was performed in 40 dogs. Nondiagnostic results occurred in 5/40 NCB (12.5%) and no FNA samples. Neoplasia was diagnosed in 17/40 dogs (42.5%), benign changes in 20/40 dogs (50%), inflammatory disorders in 0/40 dogs, and normal 2/40 dogs (5%). One of the 40 dogs (2.5%) had a diagnosis that was equivocal for neoplasia on both tests and therefore was not categorized. Of the 35 dogs that had diagnostic samples, cytopathologic and histopathologic diagnoses agreed completely in 18/35 dogs (51.4%), partially in 3/35 dogs (8.6%), and were in disagreement in 14/35 dogs (40.0%). Pathologists collaboratively reviewed diagnoses that were in disagreement or partial agreement and altered their individual diagnoses in 6/17 dogs (35.3%) to be within partial or complete agreement, respectively. Percutaneous FNA and NCB can be performed safely in dogs with sonographic splenic changes. Results suggest that adding NCB to FNA provides complementary information in dogs with suspected splenic neoplasia. This combined protocol may improve detection of splenic neoplasia and provide neoplastic subclassification.

Ultrasonographic measurement of the relative thickness of intestinal wall layers in clinically healthy cats

The normal sonographic thickness of the individual layers (ie, mucosa, submucosa, muscularis and subserosa-serosa) of the intestinal wall was evaluated in 20 clinically healthy cats. The mean thickness of the wall was 2.20, 2.22, 3.00 and 2.04 mm for duodenum, jejunum, ileum (fold) and ileum (between folds), respectively. The mean thickness of the mucosal layer was 1.27, 1.20, 0.46 and 0.49 mm for duodenum, jejunum, ileum (fold) and ileum (between folds), respectively, and its contribution to wall thickness was significantly greater than that of the other layers in the duodenum (57.7%) and jejunum (55.2%). The mean thickness of the submucosal layer was 0.36, 0.36, 1.49 and 0.53 mm for duodenum, jejunum, ileum (fold) and ileum (between folds), respectively, and its contribution to wall thickness was greater than that of the muscularis in the duodenum (16.3%), jejunum (16%) and ileum (fold) (49.8 %). The mean thickness of muscularis was 0.28, 0.35, 0.66 and 0.65 mm for duodenum, jejunum, ileum (fold) and ileum (between folds), respectively, with a corresponding contribution to wall thickness of 12.7 %, 14.4%, 22% and 31.6%. Finally, the mean thickness of serosa was 0.29, 0.31, 0.38 and 0.38 mm for duodenum, jejunum, ileum (fold) and ileum (between folds), respectively, with a corresponding contribution to wall thickness of 13.3%, 14.4%, 12.7 % and 18.7%. These values can provide baseline information that might be useful in evaluating intestinal disorders affecting preferentially some of the intestinal layers.

ULTRASONOGRAPHIC CHARACTERIZATION OF FELINE ILEOCECOCOLIC ABNORMALITIES

The clinical signs of 29 cats with ultrasonographic abnormalities at the ileocecocolic junction were reviewed. Twenty-eight cats had gastrointestinal signs, with acute vomiting and diarrhea being most prevalent. Eighteen of 29 cats had enlarged cecal lymph nodes. Focal hyperechoic mesenteric fat was noted in 18 of 29 cats, and mild focal fluid accumulation was seen in seven of 29 cats. Six cats had a round cecum, and eight cats had cecal content. The cecal wall was thickened in 19 cats, and the ileal wall was mildly thickened in six cats. Three cats had changes involving the ascending colon adjacent to the ileocecocolic junction. Fourteen cats had no ultrasonographic evidence of changes in the remainder of the gastrointestinal tract, and 13 of these 14 cats were symptomatic for gastrointestinal disease. Four cats with resolution of the ultrasonographic changes also had resolution of clinical signs. These results suggest that ultrasonographic abnormalities at the level of the ileocecocolic junction in cats are clinically significant and are seen in cats with acute vomiting or diarrhea. Fine-needle aspirates and biopsies of the ileocecocolic area had a low diagnostic yield. When no other gastrointestinal abnormalities are detected, we therefore recommend follow-up ultrasound examinations of these patients.

USE OF ULTRASOUND TO LOCATE RETAINED TESTES IN DOGS AND CATS

Ultrasound was used to locate undescended testes in 30 dogs and 4 cats where the final testicular location was determined surgically. Time between ultrasound and surgery ranged between 0 and 17 days. Forty-three testes (63.2%) were retained and 42/43 (97.7%) were detected ultrasonographically. Retained testes were located in the abdomen (n = 28) and inguinal region (n = 14). One retained testis could not be identified with use of ultrasound. Locations of retained testes ranged from the caudal pole of the kidney to the inguinal region. Descriptions of testicular echogenicity and size were not available for all testes. A 100% positive predictive value was found for all testes with use of ultrasound in both abdominal and inguinal regions. The sensitivity of ultrasound was 96.6% for abdominal and 100% for inguinal testes. Ultrasound is a sensitive test for location of retained testes, and supports the opinion that preoperative ultrasound can help facilitate location of retained testes prior to surgical exploration or laparoscopy.

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.