A REVIEW OF NONCONVENTIONAL ULTRASOUND TECHNIQUES AND CONTRAST-ENHANCED ULTRASONOGRAPHY OF NONCARDIAC CANINE DISORDERS

Modern ultrasound contrast media are gas-containing stabilized microbubbles that remain intact in the circulating blood for several minutes after intravenous injection and increase the intensity of the backscattered ultrasound. When the microbubbles disappear from the blood, they can be detected in the parenchyma of the liver and the spleen for about 30 more minutes (late liver- and spleen-specific phase). The insonated microbubbles produce second harmonic ultrasound frequencies, whose detection requires nonconventional ultrasound modalities such as pulsed inversion imaging. Nonconventional ultrasound techniques can also be used without microbubbles because second harmonics can be generated by ultrasound in tissues as well. The physical principles and advantages of nonconventional ultrasound techniques are described. The circulating microbubbles can be used not only to enhance weak Doppler signals, but also to perform dynamic contrast studies. Contrast-enhanced dynamic ultrasound studies--similar to contrast-enhanced CT and MRI examinations--have been used in humans to characterize lesions noninvasively (i.e., without biopsies) found during conventional ultrasound examinations. To map the distribution of contrast medium in a nodule or in an organ, specific scanning techniques such as stimulated acoustic emission have been developed. Stimulated acoustic emission occurs when high acoustic pressure ultrasonic waves disrupt the stationary or slowly moving microbubbles. This results in the release of a large amount of harmonic ultrasound frequencies. When the stimulated acoustic emission technique is used for dynamic studies, scanning must be interrupted several times to allow the microvasculature of the lesion to refill with microbubbles (interval delay imaging). The contrast patterns of malignant and benign hepatic nodules in humans have been the most intensively studied. Another type of dynamic study in humans measures the transit time of the contrast medium; that is, how fast the peripherally injected microbubbles reach the hepatic veins. Hepatic cirrhosis can be differentiated from other diffuse parenchymal liver diseases by a shorter transit time. Introducing nonconventional ultrasound techniques and ultrasound contrast media in veterinary diagnostic imaging may have potential value; however, intensive research should be carried out before ultrasound contrast agents can routinely be used in clinical practice.     

A Preliminary Comparison of Lidocaine and Xylazine as Epidural Analgesics in Ponies

Xylazine (0.35 mg/kg) or lidocaine (0.35 mg/kg) was injected into the epidural space of six ponies to compare their effectiveness as epidural analgesics. Each pony received both treatments at 1 week intervals with the order of treatments randomized. Xylazine produced analgesia of significantly longer duration (247 +/- 58 minutes) than that produced by an equal dose of lidocaine (135 +/- 22 minutes). Mild transient ataxia of no clinical significance developed in all ponies with both treatments. Spinal cords were removed from two ponies and examined histologically. No discernible pathologic changes were noted.     

COMPUTED TOMOGRAPHY-GUIDED PERCUTANEOUS BIOPSY: CRITERIA FOR ACCURATE NEEDLE TIP IDENTIFICATION

Precise localization of the needle tip during CT-guided percutaneous biopsy is considered to be a key element of a successful procedure. To ensure accuracy, the true needle tip must be differentiated from a false or simulated tip which appears when the CT slice encompasses only the shaft of an angled needle. By obtaining images of an aspiration biopsy needle inserted vertically into a phantom and then incrementally tilting the gantry, the authors were able to compare the characteristic features of the true tip to the simulated tip. The true tip was abrupt and distinct and had an adjacent flame-like low density artifact. The simulated tip was indistinct and tapered, yet still produced the adjacent artifact. We concluded that the shape and distinctness of the end portion of the needle itself, rather than the attendant artifact, were the most reliable criteria for accurate needle tip identification.     

Serum α-globulin fraction in horses is related to changes in the acute phase proteins

Serum electrophoresis is a useful technique to diagnose some diseases characterized by quantitative and qualitative changes in the serum proteins, such as the acute phase proteins. An increased synthesis of acute phase proteins has been associated with acute infection and inflammation. We wanted to study whether gastrointestinal diseases and disorders of the locomotor system in horses produce enough inflammatory reaction so the acute phase proteins can be detected by electrophoresis in serum. Serum total proteins were calculated, and the serum electrophoresis from 63 horses was performed. The horses were classified in 3 groups: Group I (19 healthy horses), Group II (20 horses suffering from inflammatory disorders of the gastrointestinal tract), and Group III (24 horses with inflammatory disorders of the locomotor system). Results indicated an increase of the acute phase proteins only in patent inflammatory disorders that showed a rapid progression. A global increase in those proteins was observed only for α₁-globulins from Group II.     

Luxation of the Canine Shoulder Joint to Maximize Exposure for Treatment of Osteochondritis Dissecans

Luxation of the humeral head by internal rotation of theforelimb with the shoulder joint in flexion will maximize exposure of the humeral head for treatment of osteochondritis dissecans of the canine shoulder. The procedure was performed on 51 normal dogs and on 13 shoulders of 11 dogs with osteochondritis dissecans. Postoperative evaluation was obtained in all 51 normal dogs and 8 clinical patients. Postoperative seromas were seen in two dogs; one was presumed to be due to reaction to the suture material used, and the other to unrestricted exercise during the immediate postoperative period. There were no other complications. The time for recovery to normal ambulation was similar to those reported for other approaches.     

Mandibular Fractures in the Cat A Retrospective Study

A retrospective study was made of 75 mandibular fractures in 62 cats. Mandibular fractures comprised 14.5% of all fractures seen in 517 cats. Automobile trauma was the cause of injury in more than 50% of the cases. The mean age of patients was 29.5 months. Symphyseal fractures were most common (73.3%), followed by fractures of the body (16%), condyle (6.7%), and coronoid process (4%). Sixty-seven percent of the fractures were stabilized. Cerclage and interfragmentary wiring were the most common forms of fixation. Antibiotics were administered to 73.6% of the patients. Complications were reported in 24.5% of the cats. Malocclusion and soft tissue infections were the most frequent complications. Complications developed more commonly in cats with multiple or open fractures. Clinical union occurred by an average of 6 weeks (range, 3-12 weeks) for symphyseal fractures, 10 weeks (range, 8-16 weeks) for body fractures, 6 weeks for coronoid fractures, and 6 weeks (range, 4-8 weeks) for condylar fractures.     

Partial pressure of end-tidal CO2 sampled via an intranasal catheter as a substitute for partial pressure of arterial CO2 in dogs

Objective: To demonstrate correlation and clinical usefulness of the partial pressure of end‐tidal CO₂ (ETCO₂) measurement by nasal catheter placement in sedated dogs with and without concurrent nasal oxygen administration as a substitute for partial pressure of arterial CO₂ (PaCO₂). Design: Prospective, cross‐over trial. Setting: University of Saskatchewan veterinary research laboratory. Animals: Six cross‐breed dogs with a mean (±SD) weight of 29.1±4.03 kg. Interventions: All dogs were sedated with 5 μg/kg medetomidine intravenously (IV) and an arterial catheter was placed in a dorsal pedal artery for removal of blood for gas analysis. A nasal catheter was placed in the ventral meatus and connected to a capnometer for ETCO₂ measurements in all dogs. Dogs receiving supplemental nasal oxygen had a second nasal catheter placed in the contralateral naris. Measurements and main results: In the group without nasal oxygen supplementation, the ETCO₂ measurement underestimated (negative bias) the PaCO₂ by ?2.20 mmHg with limits of agreement (95% confidence interval) of ?5.79, 1.39 mmHg. In the group receiving oxygen supplementation, ETCO₂ measurement underestimated (negative bias) the PaCO₂ by ?2.46 mmHg with limits of agreement (95% confidence interval) of ?8.42, 3.50 mmHg. Conclusions: The results of this study demonstrate that ETCO₂ monitoring via a nasal catheter provides a clinically acceptable substitute to arterial blood gas analysis as a means of monitoring ventilation in healthy, sedated dogs. The limits of agreement were within acceptable limits with and without concurrent insufflation of oxygen.     

Nonlymphomatous Hepatobiliary Masses in Cats: 41 Cases (1972 to 1991)

The medical and necropsy records of 41 cats diagnosed with nonlymphomatous hepatobiliary (NLHB) masses, including neoplasia and cysts, were reviewed. Overall, benign masses (n = 27) were more common than malignant ones (n = 14). The single most common malignancy was cholangiocellular carcinoma. The median age at diagnosis was significantly lower ( P < .01) for cats with malignant rather than benign disease. Clinical signs associated with hepatobiliary neoplasia were usually vague and included lethargy, vomiting, and anorexia, often present for at least 2 weeks before presentation. Benign masses were an incidental finding in significantly more ( P < .01) of the cases than were malignant masses. Median values for alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin were significantly higher ( P < .05) in cats with malignant versus benign masses. The prognosis for malignant disease was poor, with 86% of the cats dying or being euthanatized during hospitalization. Cats with benign disease that underwent exploratory celiotomy were more likely to recover and warranted a more favorable prognosis than cats with malignant tumors. Factors associated with malignancy included age at presentation, presence of clinical signs at presentation, and specific serum chemistry changes.     

COMPUTED TOMOGRAPHIC FINDINGS OF DOGS WITH CUBITAL JOINT LAMENESS

The purpose of this study was to identify the incidence of abnormal computed tomography (CT) findings in dogs with lameness of one or both elbows. CT examinations of 102 elbows in 51 dogs were reviewed individually and by group consensus by 3 examiners and graded for various abnormalities. Frequently encountered abnormalities included abnormal shape and sclerosis of the medial coronoid process of the ulna, irregularity of the radial incisure of the ulna, and ulnar trochlear notch sclerosis. Other abnormalities included distinct/separate or fissure/in situ fragmentation of the medial coronoid; lucency of the radial incisure; ununited anconeal process; sclerosis, lucency, or flattening of the medial aspect of the humeral condyle; osteophyte formation; and joint incongruity. In conclusion, CT of the canine cubital joint is useful in identification of various lesions beyond simple fragmentation of the medial coronoid process of the ulna.