Nasal angioleiomyoma in 2 dogs

This case report describes 2 dogs, an Appenzeller Mountain dog and an Irish Wolfhound, with angioleiomyoma within the nasal cavity. Endoscopic surgical resection resulted in cure in both dogs. Macroscopically and on diagnostic imaging, tumor masses may appear malignant because of local turbinate destruction. This highlights the importance of histological examination before any recommendations are made to owners because tumors of the nasal cavity may be benign and surgery curative.

Diagnostic benefits of platelet-to-lymphocyte, neutrophil-to-lymphocyte, and albumin-to-globulin ratios in dogs with nasal cavity diseases

BACKGROUND

A multimodal approach for diagnostic tests under anesthesia is required to diagnose nasal cavity pathology (NP) reliably in dogs. Blood test results may provide clues to the suspected NP.

METHODS

This prospective blinded study assessed 72 dogs with chronic nasal discharge due to NPs, and 10 healthy dogs as the control group (CG). NPs were diagnosed using whole-body computed tomography (CT), upper airway endoscopy, examination of nasal mucosal swabs by bacterial and fungal culture, and histopathological examination of nasal mucosa biopsies. The exclusion criteria were the presence of any additional diseases or corticosteroid pre-treatment. In consideration of these exclusion criteria, 55 dogs entered the study. Dogs were classified into benign (benign tumors, idiopathic rhinitis (IR), and others) and malignant (carcinomas and sarcomas) NP groups. Blood count and blood chemistry tests were performed. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and albumin-to-globulin ratio (AGR) were calculated and compared.

RESULTS

25 dogs with malignant NP (13 and 12 with carcinomas and sarcomas, respectively) and 30 dogs with benign NP (seven with benign tumors,13 with IR, and 10 others) were included. In general, in dogs with NP there were only slight abnormalities in complete blood count. However, PLR was significantly higher in dogs with malignant NP (carcinoma and sarcoma) than in those with benign NP and in the CG. Compared with the CG, the NLR was significantly increased in all dogs with NP, and the AGR was mild but significantly lower, except in dogs with sarcomas and benign tumors.

CONCLUSIONS

In dogs with nasal disease alone, there are usually no marked abnormalities in blood count. However, while mildly increased NLR and decreased AGR can be observed in almost all NPs, an increased PLR may indicate a malignant NP and can be used as an additional screening tool in dogs with nasal discharge due to nasal cavity pathology.

[Nasal obstruction: Odontogenic cysts in 4 brachycephalic dogs]

OBJECTIVE

Odontogenic cysts may be of developmental or inflammatory origin. They are frequently observed in brachycephalic dogs. Due to their expansive growth, cysts in the maxilla may extend into the nasal cavity, obstruct the nasal airway and cause nasal discharge. Epithelial cysts may lead to a comparable clinical picture. A new endonasal endoscopic intervention for the removal of these cysts is described.

MATERIAL AND METHODS

Four brachycephalic dogs (Boxer, Chihuahua, French bulldog, Pug) with unilateral cysts obstructing the nasal cavity were included in the study. The animals underwent clinical examination, computed tomography (CT) imaging and rhinoscopy examination. Histopathologic evaluation of the cyst wall was performed. In addition to dental surgery and conventional extraction of the involved tooth, the cyst wall was removed by endoscopic intervention via the physiologic nasal opening. Clinical course following treatment was assessed by rhinoscopy and CT.

RESULTS

The main clinical signs were unilateral or bilateral serous to hemorrhagic nasal discharge. Nasal airflow was restricted in all patients. Removal of the cysts and involved teeth did not lead to any intra- and postoperative complications. No recurrence of the cysts was observed. Histologic diagnosis consisted of an epidermoid cyst, a follicular cyst, a radicular cyst, and a canine odontogenic parakeratinized cyst (COPC). Neoplastic transformation was excluded in all cases.

CONCLUSIONS

Removal of the cyst wall may be performed by means of minimally invasive endoscopic intervention via the physiologic nasal entrance. The procedure is curative and carries the risk of only few complications. In cases in which treatment is restricted to extraction of the affected tooth, the nasal airway may remain obstructed due to a calcified cyst wall.

CLINICAL RELEVANCE

In brachycephalic dogs, oronasal defects due to dental pathology are the most common reason for chronic nasal discharge, whereas in normocephalic dogs nasal neoplasia are. Odontogenic cysts carry importance as differential diagnosis of nasal discharge.

Prevalence and characterization of middle ear effusion in 55 brachycephalic dogs

OBJECTIVE

 Multiple, breeding-related malformations of the skull of brachycephalic dogs are well-known. Whereas the eye-catching deformities of the nose that lead to dramatic respiratory problems are obvious, changes of the middle ear are often an incidental finding on CT examinations and usually clinically inapparent. The objectives of this work were to investigate the prevalence and characteristics of middle ear effusion in brachycephalic dog breeds presented for multilevel surgery of upper airway obstructions.

MATERIAL AND METHODS

 Brachycephalic dogs with incidental middle ear effusion detected on CT scans obtained prior to surgical treatment of brachycephalic airway syndrome were prospectively enrolled. A perendoscopic tympanocentesis followed by macroscopic description, microscopic cytology and bacteriological analysis of the fluid was performed.

RESULTS

 Prevalence of middle ear effusion in all dogs presented to the department during the study period was 55/170 (32 %) in 86 middle ears. The only breeds suffering from MEE were French Bulldogs (FB) with a prevalence of 35/66 (53 %) and Pugs with a prevalence of 20/79 (25 %). Tympanocentesis was performed in 80 ears. In the majority of cases the effusion was either mucoid or serous, with a honey-like or ochre colour.Bacteriology was available for 76 ears and tested positive in 34 (45 %) cases. Cytology was performed in 73 ears and revealed all effusions to contain inflammatory cells with a high concentration in 23 (31.5 %) cases.

CONCLUSIONS AND CLINICAL RELEVANCE

 Brachycephalic dogs presented for surgical treatment of brachycephalic airway syndrome have a high prevalence of incidental middle ear effusions. Cytological findings differ from previously reported analyses of effusions in Cavalier King Charles spaniels with clinical symptoms of primary secretory otitis media, where usually cell-free effusions are found. A study comparing effusions of brachycephalic dogs with vestibular disease to those found as an incidental condition is warranted.

Brachycephaly in French bulldogs and pugs is associated with narrow ear canals

BACKGROUND

Brachycephalic dog breeds have multiple skull malformations which may lead to anatomical changes in the external auditory canal. It is our frequent observation that in the otoscopic examination of the external ear in these breeds we are unable to visualise the tympanic membrane as a consequence of extreme narrowing of the proximal ear canal. Additionally brachycephalic dogs reportedly are predisposed to otitis externa (OE) and otitis media.

OBJECTIVES

To characterizse the transition of the cartilaginous ear canal to the bony meatus acusticus externus using computed tomography (CT) and to investigate a possible association with OE in brachycephalic dogs.

MATERIALS AND METHODS

Seventy-five client-owned dogs [pugs (n = 20), French bulldogs (n = 55)] were included and assessed for OE using an owner questionnaire and otoscopic and cytological examinations. In dorsal plane CT scans, the diameter of the porus acusticus externus was measured using novel methodology. The results were compared with a normocephalic control group without preexisting otological disorders.

RESULTS

Brachycephalic dogs had a significantly smaller porus acusticus externus diameter (2.6 mm) than normocephalic dogs (5.0 mm). Of the brachycephalic dogs, 32% had OE yet this was not statistically significantly related to the diameter of the porus acusticus externus. Middle ear effusion (44%) and narrowing of the external ear canal (82.6%) were significantly more frequent in brachycephalic dogs. Only five of 150 eardrums could be visualised otoscopically.

CONCLUSIONS AND CLINICAL RELEVANCE

Malformation of the porus acusticus externus causes severe stenosis of the proximal ear canal in brachycephalic dogs. A connection between stenosis of the external auditory canal and OE could not be confirmed.

Evaluating malformations of the lacrimal drainage system in brachycephalic dog breeds: A comparative computed tomography analysis

OBJECTIVES

This study aimed to investigate and compare the anatomical features of the nasolacrimal drainage system (NDS) in three brachycephalic dog breeds with those of normocephalic dogs, taking into account how the NDS was related to the malformed brachycephalic head.

ANIMALS

Fifty-one brachycephalic dogs were examined, comprising 23 Pugs, 18 French Bulldogs, and 10 English Bulldogs. Six normocephalic dogs of different breeds served as a comparison.

METHODS

Computed tomographic dacryocystography was performed. Parameters such as length, angulation, and gradient were determined. Crossing of the nasolacrimal duct (NLD) beneath the maxillary canine root, as well as the incidence of an accessory opening, were also analyzed.

RESULTS AND CONCLUSIONS

In all three brachycephalic breeds, the NDS was grossly malformed. We regard this as a further consequence of exaggerated breeding for a short head conformation. While the length of the NLD was substantially reduced by 41 to 57 percent in brachycephalic dogs, their lacrimal canaliculi were two to three times as long as those of normocephalic dogs. Varying parts of the nasolacrimal drainage system followed an inverse direction in short-headed dogs, giving the entire nasolacrimal apparatus an anomalous U- or V-shaped appearance. The NLD exhibited a three to five times steeper alignment in brachycephalic dogs than in normocephalic ones. Obviously, this strong slope did not cause clinical symptoms only because there was an aberrant outflow pathway. The brachycephalic dogs consistently exhibited an accessory opening, through which most of fluid escaped into the posterior nasal cavity instead of through the common route into the nasal vestibule via the nasolacrimal ostia.

Intraoperative and major postoperative complications and survival of dogs undergoing surgical management of epiglottic retroversion: 50 dogs (2003-2017)

OBJECTIVE

To report intraoperative and major postoperative complications in dogs treated surgically for epiglottic retroversion (ER), compare the incidence of major postoperative complications between procedures, and report survival of surgically treated dogs.

STUDY DESIGN

Multi-institutional retrospective study.

SAMPLE POPULATION

Fifty dogs treated with 78 procedures.

METHODS

Medical records of dogs diagnosed and surgically treated for ER from 2003 to 2017 at 11 institutions were reviewed. Complications were divided into intraoperative and major postoperative complications.

RESULTS

Intraoperative complications occurred during 2 of 78 (2.6%) procedures. Thirty-six major postoperative complications were documented in 22 dogs after 36 of 74 (48.7%) procedures. Postoperative complications occurred after 7 of 12 (58.3%) nonincisional epiglottopexy, 23 of 43 (53.5%) incisional epiglottopexy, 2 of 4 (50%) partial epiglottectomy, 2 of 12 (16.7%) subtotal epiglottectomy, and 2 of 3 (66.7%) other surgical procedures. Epiglottopexy failure was the most common major postoperative complication. The incidence of major postoperative complications did not differ between procedures (P = .1239), although, when combined, epiglottopexy procedures (30/55) had a higher incidence of complications than epiglottectomy procedures (4/16; P = .048). Thirty (60%) dogs were alive at a median of 928 days (range, 114-2805), 8 (16%) were lost to follow-up after 411 days (range, 43-1158), and 12 (24%) were dead/euthanized after 301.5 days (range, 3-1212). Median survival time was not reached after a median of 716 days.

CONCLUSION

Although intraoperative complications were uncommon, major postoperative complications were common, especially after epiglottopexy procedures.

CLINICAL SIGNIFICANCE

Although surgical treatment of ER is associated with a high rate of major postoperative complications, especially epiglottopexy procedures, long-term survival can be achieved.

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) among employees and in the environment of a small animal hospital

The aim of the study was to investigate methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) among employees of a small animal hospital and the hospital environment. In total, 96 swabs from employees and 73 swabs from the clinic environment were investigated. Cation-adjusted-Mueller-Hinton broth (CAMHB) + 6.5% NaCl was used for enrichment before plating on Mueller-Hinton (MH) agar with 2% NaCl and 0.25 mg/L oxacillin. The staphylococcal species was determined using MALDI-TOF MS. The isolates were subjected to mecA-PCR, macrorestriction analysis, and antimicrobial susceptibility testing. MRSA were present in five nasal swabs of the 55 employees tested and in six environmental samples, MRSP in two employees (nasal and hand swabs, each) and in three environmental samples. All isolates harboured mecA. Susceptibility testing revealed that all but one of the isolates were multiresistant. All isolates were resistant to β-lactams and fluoroquinolones. All but one of the isolates were resistant to macrolides and lincosamides. A single MRSA was resistant to gentamicin. All MRSP were resistant to trimethoprim/sulfamethoxazole and non-susceptible to gentamicin. One isolate was also resistant to tetracycline. Macrorestriction analysis revealed three main SmaI patterns for MRSA and two main SmaI patterns for MRSP. All environmental isolates were found in areas of high people and animal traffic, such as dog ward areas, waiting and triage rooms. The finding of indistinguishable MRSA or MRSP among employees and in the environment of the small animal hospital suggests the possibility of transfer of these bacteria between humans, animals, and the hospital environment.

Konzentration des C-reaktiven Proteins (CRP) im Blutserum bei Hunden mit postoperativen Wundheilungsstörungen

Gegenstand und Ziel: Ziel dieser Studie war die Beurteilung des perioperativen Verlaufs der Konzentration des kaninen C-reaktiven Proteins (CRP) im Blutserum bei komplikationsloser Wundheilung und bei postoperativen Wundheilungsstörungen. Material und Methoden: Entsprechend dem postoperativen Verlauf der Wundheilung wurden 99 Hunde in folgende Gruppen eingeteilt: komplikationslose Wundheilung (Kontrollgruppe, n = 57), Wundinfektion (n = 11), Nahtdehiszenz (n = 5), Serom (n = 6), Hämatom (n = 7), passagerer Reizzustand (n = 12) und sonstige Komplikationen (n = 1). Ergebnisse: Patienten mit komplikations-loser Wundheilung zeigten klinisch im postoperativen Verlauf eine stetige Abschwächung der initialen lokalen Entzündungsreaktion. Auch die CRP-Konzentration war durch einen initialen Gipfel und einen sich anschließenden stetigen Abfall charakterisiert. Bei Patienten, deren Wundheilung durch eine fortbestehende oder wiederaufflammende Entzündung charakterisiert war, ergaben sich postoperativ fast immer unverändert hohe CRP-Konzentrationen oder ein deutlicher Wiederanstieg sowie höhere CRP-Konzentrationen als bei den Kontrolltieren. Dies konnte nicht nur bei Patienten mit klinisch sichtbarer Wundinfektion oder Nahtdehiszenz nachgeweisen werden, sondern auch bei Patienten ohne eindeutige klinische Anzei-chen einer Nahtdehiszenz oder Wundinfektion (passagerer Reizzustand). Demgegenüber zeigten Patienten mit Serom oder Hämatom im weiteren postoperativen Verlauf weder klinisch eine ausgeprägte Entzündungsreaktion noch erhöhte CRP-Konzentrationen. Schlussfolgerung: Die serielle Bestimmung der CRPKonzentration stellt einen objektiven Parameter zur Beurteilung der Wundheilung dar. Klinische Relevanz: Unverändert hohe oder deutlich wiederansteigende CRP-Konzentrationen sind, unter Beachtung bestimmter Voraussetzungen, eine Indikation, weitere diagnostische Maßnahmen einzuleiten und therapeutische Gegenmaßnahmen zu ergreifen.

Magnetresonanztomographische Untersuchung des Kiefergelenks von Hund und Katze

Gegenstand und Ziel: In der Magnetresonanztomographie (MRT) beeinflusst die Empfängerspule besonders bei kleinen Objekten die Bildqualität erheblich. Ziel der Untersuchung war, das kanine und feline Kiefergelenk mit zwei verschiedenen Spulen darzustellen und deren Einfluss auf die Bildqualität zu prüfen. Material und Methoden: Die Kiefergelenke von zwei Hunden und zwei Katzen wurden mit einer Kniespule und einer flexiblen Oberflächenspule im MRT (0,5 Tesla) dargestellt. Das Untersuchungsprotokoll umfasste eine T1-gewichtete Spinecho-Sequenz, eine T2-gewichtete Turbospinecho-Sequenz und eine protonengewichtete Sequenz (Schichtdicke je 3 mm) sowie Gradientenecho-Sequenzen (SD: 1–1,5 mm) in sagittaler Ebene. In einer Blindstudie bewerteten drei Untersucher die Bildqualität anhand der Merkmale “Bildkontrast”, “Knochenstruktur”, “Ortsauflösung” und “Signal-Rausch-Verhältnis” anhand einer fünfstufigen Skala. Ergebnisse: Die Oberflächenspule ergab bei etwa der Hälfte der Aufnahmen hinsichtlich “Bildkontrast”, “Knochenstruktur” und “Ortsauflösung” eine bessere Bildqualität, bei ca. 50% der MRT-Bilder bestand kein Unterschied zwischen den Spulen. Beim Kriterium “Signal-Rausch-Verhältnis” zeigte sich die Oberflächenspule sogar bei über 90% der Bilder der Kniespule überlegen. Nur bei 5% der Aufnahmen fanden sich keine Differenzen zwischen den Spulen. Die Oberflächenspule erzielte sowohl beim Kiefergelenk der Hunde als auch beim kleineren Kiefergelenk der Katzen bessere Bewertungen. Schlussfolgerungen und klinische Relevanz: Die Darstellung kleiner Gelenkstrukturen wird entscheidend durch die Ortsauflösung der MRT-Bilder beeinflusst. Daher sollten eine geeignete Spule und ein kleines Messfeld eingesetzt werden. Die Ergebnisse zeigen, dass sich auch mit einem Niederfeld-MRT die anatomischen Strukturen des Kiefergelenks von Hunden und Katzen hochauflösend abbilden lassen. Die Resultate sind grundsätzlich auf Geräte anderer Feldstärke übertragbar, doch müssen die technischen Parameter und die verwendete Spule an das vorhandene MRT-Gerät angepasst werden.

Echokardiographische Untersuchung der linksatrialen Größe bei gesunden Katzen und Katzen mit linksventrikulärer Hypertrophie

Gegenstand und Ziel: Die Größe des linken Vorhofs (LA) hat bei Katzen mit Kardiomyopathie sowohl diagnostische als auch prognostische Bedeutung und beeinflusst therapeutische Entscheidungen. Ziel dieser Arbeit war, die Größe des LA im zweidimensionalen (2-D) Echokardiogramm und im M-Mode bei gesunden Katzen und Katzen mit linksventrikulärer (LV) Hypertrophie zu quantifizieren und die Messmethoden miteinander zu vergleichen. Material und Methode: Insgesamt wurden 59 Katzen untersucht und in Gruppen eingeteilt. Die Kontrollgruppe bestand aus 26 gesunden Katzen und die Untersuchungsgruppen aus 33 Katzen mit hypertropher Kardiomyopathie (HCM) oder sekundärer LV Hypertrophie infolge arterieller Hypertension. Bei diesen Tieren erfolgte eine Unterteilung in asymptomatische und symptomatische Katzen. Fünf unterschiedliche echokardiographische Messmethoden fanden Anwendung. Das Verhältnis von Durchmesser des LA und Dimension der Aorta (LA/Ao) wurde aus dem M-Mode aus der langen und kurzen rechts-parasternalen Achse sowie aus der 2-D Kurzachse berechnet und Grenzwerte zur Diagnostik einer linksatrialen Vergrößerung ermittelt. Ergebnisse: In der Kontrollgruppe beeinflussten die Herzfrequenz, nicht jedoch die Körpermasse oder das Alter (p > 0,05) die Größe des LA. Eine linksatriale Vergrößerung konnte im Vergleich zur Gruppe der gesunden Katzen mit jeder angewandten Messmethode dargestellt werden (p < 0,004). Die Vergrößerung des LA wurde für jeden LA/Ao-Quotienten mit dem linksatrialen Durchmesser, gemessen in der 2-D langen Achse verglichen. Die Übereinstimung zwischen diesen Messmethoden war mittelmäßig bis moderat (Kappa = 0,39–0,57). Schlussfolgerung und klinische Relevanz: Diese Studie zeigt, dass eine Vergrößerung des LA bei der Katze durch unterschiedliche echokardiographische Messmethoden dargestellt werden kann. Die Grenzwerte der Methoden differieren, sodass die Ergebnisse der einzelnen Methoden nicht miteinander vergleichbar sind.

[Magnetic resonance imaging anatomy of the feline salivary glands]

OBJECTIVE

The aim of the study was to define anatomical characteristics of feline salivary glands using magnetic resonance imaging (MRI) and to describe landmarks for their reliable identification.

MATERIAL AND METHODS

Heads of 37 adult cats without signs of diseased salivary glands on clinical examination or history were examined. In cats included in the prospective part of the study, the MRI study was completed within one hour after euthanasia (n = 16). In the retrospective part, previously performed MRI studies were evaluated (n = 21). The prospective part of the study included the following standardized sequences: T2-weighted (T2W) turbo spin echo (TSE), T2W fat-suppressed TSE and proton density weighted (PDW) TSE images in a transverse plane as well as T1-weighted (T1W) fast field echo (FFE) in the transverse, sagittal and dorsal planes. In the retrospective part, T2W TSE and T1W TSE transverse images pre- and post-contrast were analyzed. Initially, identification and delineation of the salivary glands from surrounding tissue was assessed. Anatomical structures of the head were then identified and defined as landmarks. The dimensions of the glands were measured on T2W TSE images and the signal intensity in relation to that of fat and muscle was described using all sequences.

RESULTS

In total, 95.9% of the parotid glands and 100% of the mandibular glands could be visualized on T1W TSE and FFE images and on T2W TSE images. Additionally, 93.3% of the zygomatic glands were identified on T2W TSE sequences and 82.5% on T1W TSE and FFE images. The ventral buccal glands could be demarcated in some sequences (T2W TSE: 51.4%, T1W TSE and FFE: 18.9%). Anatomical landmarks facilitated gland identification. Comparing the size of the salivary glands of both groups revealed differences of up to 2 mm.

CONCLUSION

Both the large salivary glands (Glandula [Gl.]. parotis and Gl. mandibularis) and the small salivary glands (Gl. zygomatica and Gl. buccalis ventralis) of the cat can be reliably identified on MRI images.

Inside the brachycephalic nose: conchal regrowth and mucosal contact points after laser-assisted turbinectomy

This prospective observational study analyzed conchal regrowth after laser-assisted turbinectomy (LATE) in brachycephalic dogs and the mucosal contact of regrown conchae. Eighty brachycephalic dogs (41 pugs, 39 French bulldogs [FBs]) that underwent LATE because of obstructing conchae were evaluated by endoscopy 7 days and 6 mo after surgery. At 6 mo, 96% of FBs' and 65% of pugs' nasal cavities showed regrowth of turbinates. FBs showed higher growth grades than pugs. Revision surgery because of reobstructing regrowth was required in the nasal cavities of 17% of FBs and 3% of pugs. The mean number of contact points reduced from 3.0 in FB and 1.7 in pugs before surgery to 1.2 in FB and 0.2 in pugs after conchal regrowth. Recollapse of nares after surgery significantly influenced the frequency of reoccurrence of contact points. LATE was proven to be an effective treatment of intranasal obstruction caused by mucosal contact between conchae. Conchal regrowth commonly occurs after surgical removal, but the new conchae cause less obstruction due to a significant reduction in number of contact points. Revision surgery because of reobstruction is rarely necessary. The important physiologic functions of conchae make nonobstructing regrowth desirable.

[Computed tomographic anatomy of the salivary glands in the cat]

OBJECTIVE

The aim of the study was to define anatomical characteristics of the feline salivary glands in cross-sectional images obtained by unenhanced computed tomography (CT) and to describe landmarks for a reliable identification.

MATERIAL AND METHODS

Heads of adult normocephalic cats without indications of cephalic disease were examined. Cats were included in the prospective part of the study when examined no later than 1 hour post mortem (n = 16). In the retrospective part of the study, previous CT-studies were evaluated (n = 25). The results of both groups were evaluated separately. Initially, the possibility of identifying and delineating the salivary glands from the surrounding tissue was assessed. Anatomical structures of the head were then defined as landmarks. Dimensions and density (Hounsfield units, HU) of the salivary glands were determined based on transversal and reconstructed sagittal images.

RESULTS

In total, 94.3% of the parotid glands, 90.7% of the mandibular glands and 96.8% of the zygomatic glands could be delineated. The remaining salivary glands could not be identified. Anatomical landmarks, including the external ear canal, the musculus (M.) masseter, the M. pterygoideus medialis and the bulbus oculi facilitated the identification. Comparing the size of the salivary glands of both groups revealed differences (measured lateromedially and rostrocaudally) in size of ≤   2 mm. The definable salivary glands varied significantly in their density. The mean density of the glandula (Gl.) parotis was 65 HU, of the Gl. mandibularis 62 HU and of the Gl. zygomatica 57 HU. The comparisons of densities of both sides of the glands did not show statistically significant differences.

CONCLUSIONS

The large salivary glands (Gl. parotis and Gl. mandibularis) and the Gl. zygomatica of the cat can be reliably identified in CT-images. CT landmarks and data regarding the size and density of each gland could be gathered. The remaining minor salivary glands could not be delineated accurately. The difference in depicting the glands can be explained mainly by a lack of contrast with the surrounding tissue.

[Options for the reduction of magnetic susceptibility artifacts caused by implanted microchips in 0.5 Tesla magnetic resonance imaging]

OBJECTIVE

Microchips contain ferromagnetic materials, which lead to severe focal image interferences when performing magnetic resonance imaging (MRI). Very small animals are particularly prone to these susceptibility artifacts, which may hinder analysis of the neck-region MRI image. We investigated the impact of sequence type on the artifact's size and determined the optimal imaging parameters to minimize these artifacts. Furthermore, the minimum distance between the microchip and the spinal canal required to assess the spinal structures should be determined.

MATERIAL AND METHODS

Investigations were performed on the cadavers of 26 cats and two dogs using a low-field MRI System (field strength 0.5 Tesla). To quantify susceptibility artifacts, several sequence types (spin echo, turbo-spin echo (TSE), gradient echo) and imaging parameters (echo time (TE), voxel volume, frequency direction) were systematically varied. Additionally, computed tomography imaging was performed to determine the distance between the microchip and the spinal canal.

RESULTS

The size of the artifact was smallest with T1-weighted TSE sequences. A short TE (10 ms) and a small voxel size (acquisition matrix 256 x 256 pixels, field of view 160 mm, slice thickness 2 mm) significantly reduced artifact size. Furthermore, it could be shown that by changing the frequency- and phase-encoding direction, the shape and orientation of the maximum dimension of the artifact could be influenced. Even when using an optimized T1-weighted TSE sequence, it was impossible to evaluate the spinal cord when the distance between the microchip and the center of the spinal canal was < 19  mm.

CONCLUSION AND CLINICAL RELEVANCE

In MR studies of the cervical spine of small dogs and cats, microchips can cause severe susceptibility artifacts. Because of the small distance between the microchip and the spinal structures, spinal evaluation may be limited or impossible. The investigations demonstrated that the adjustment of sequence parameters helps to significantly minimize artifact size and shape. The greatest reduction in artifact size was achieved by using a T1-weighted TSE sequence.

Neurologic outcome after thoracolumbar partial lateral corpectomy for intervertebral disc disease in 72 dogs

OBJECTIVE

To determine neurologic outcome and factors influencing outcome after thoracolumbar partial lateral corpectomy (PLC) in dogs with intervertebral disc disease (IVDD) causing ventral spinal cord compression.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs with IVDD (n = 72; 87 PLC).

METHODS

Dogs with IVDD between T9 and L5 were included if treated by at least 1 PLC. Exclusion criteria were: previous spinal surgery, combination of PLC with another surgical procedure. Neurologic outcome was assessed by: (1) modified Frankel score (MFS) based on neurologic examinations at 4 time points (before surgery, immediately after PLC, at discharge and 4 weeks after PLC); and (2) owner questionnaire. The association of the following factors with neurologic outcome was analyzed: age, body weight, duration of current neurologic dysfunction (acute, chronic), IVDD localization, breed (chondrodystrophic, nonchondrodystrophic), number of PLCs, degree of presurgical spinal cord compression and postsurgical decompression, slot depth, presurgical MFS. Presurgical spinal cord compression was determined by CT myelography (71 dogs) or MRI (1 dog), whereas postsurgical decompression and slot depth were determined on CT myelography (69 dogs).

RESULTS

MFS was improved in 18.7%, 31.7%, and 64.2% of dogs at the 3 postsurgical assessments, whereas it was unchanged in 62.6%, 52.8%, and 32.0% at corresponding time points. Based on owner questionnaire, 91.4% of dogs were ambulatory 6 months postsurgically with 74.5% having a normal gait. Most improvement in neurologic function developed within 6 months after surgery. Presurgical MFS was the only variable significantly associated with several neurologic outcome measurements (P < .01).

CONCLUSIONS

PLC is an option for decompression in ventrally compressing thoracolumbar IVDD. Prognosis is associated with presurgical neurologic condition.

[Sonographic measurement of soft-palate thickness and comparison with the measurement by computed tomography]

OBJECTIVE

The aim of this study was to measure the thickness of the soft palate at specific locations in normocephalic dogs using sonography and computed tomography (CT), and to subsequently compare the two different methods.

MATERIAL AND METHODS

A total of 15 normocephalic dogs were examined under general anesthesia. The CT was performed while patients were in a sternal recumbent position, their mouth held open by placing their upper jaw on a positioning device. Dorsal recumbency together with submental and midsagittal positioning of the transducer were chosen for sonography. Measurements were made in both sonographic and reconstructed sagittal CT images. Two measuring points (MP) were defined for measuring the cranial and the middle part of the soft palate (MP1: 1 cm caudal to the transition from the hard to the soft palate; MP2: at the origin of the dorsal pharyngeal muscles). It was investigated whether repeated procedures with one measuring method provided consistent values and, furthermore, whether the two different measuring methods (sonography and CT) provided comparable data.

RESULTS

The data acquired by repeat measurements within one method corresponded very well. However, the data provided by the two different measurement methods showed varying results for the first measuring point and was even greater for the second measuring point. Sonography overestimated the measurements obtained by CT by up to 0.26 cm for MP1 and up to 0.79 cm for MP2.

CONCLUSION

Due to the significant discrepancies in their results, the two measurement methods are not interchangeable. Sonography showed good reliability for repeat measurements. Consequently, the variable values between CT and sonography appeared to result from differing examination conditions. Sonography may be a rapid and non-invasive diagnostic tool to measure soft palate thickness if the applied method proves to be applicable in clinical practice.

Thoracolumbar spinal arachnoid diverticula in 5 pug dogs

Clinical features, myelography, and computed tomography imaging findings as well as neurological outcome with and without surgery in 5 pug dogs with thoracolumbar arachnoid diverticula are described. Short-term prognosis after surgical therapy may not be as good as reported for other canine breeds, since immediate postsurgical deterioration is possible. Improvement of neurological deficits beyond the presurgical status may take several months.

Functionality of veterinary identification microchips following low- (0.5 tesla) and high-field (3 tesla) magnetic resonance imaging

The ability to read patient identification microchips relies on the use of radiofrequency pulses. Since radiofrequency pulses also form an integral part of the magnetic resonance imaging (MRI) process, the possibility of loss of microchip function during MRI scanning is of concern. Previous clinical trials have shown microchip function to be unaffected by MR imaging using a field strength of 1 Tesla and 1.5. As veterinary MRI scanners range widely in field strength, this study was devised to determine whether exposure to lower or higher field strengths than 1 Tesla would affect the function of different types of microchip. In a phantom study, a total of 300 International Standards Organisation (ISO)-approved microchips (100 each of three different types: ISO FDX-B 1.4 × 9 mm, ISO FDX-B 2.12 × 12 mm, ISO HDX 3.8 × 23 mm) were tested in a low field (0.5) and a high field scanner (3.0 Tesla). A total of 50 microchips of each type were tested in each scanner. The phantom was composed of a fluid-filled freezer pack onto which a plastic pillow and a cardboard strip with affixed microchips were positioned. Following an MRI scan protocol simulating a head study, all of the microchips were accurately readable. Neither 0.5 nor 3 Tesla imaging affected microchip function in this study.

The vacuum phenomenon in intervertebral disc disease of dogs based on computed tomography images

OBJECTIVES

Vacuum phenomenon is suspected to be indicative of disc degeneration and subsequent herniation. The objective of this study was to assess the reliability of vacuum phenomenon for identification of herniated discs causing neurological signs. Prevalence of vacuum phenomenon and influencing factors in dogs with disc herniation were determined.

METHODS

Retrospective review of computed tomography scans from dogs with suspected disc herniation for the presence of gas within intervertebral disc space with subsequent comparison of vacuum phenomenon and herniated disc as confirmed by surgery. Subgroups were created (chondrodystrophic, non-chondrodystrophic and unknown classification) to analyse prevalence and influencing factors (age, breed and gender) for vacuum phenomenon and agreement with herniated disc.

RESULTS

Prevalence of vacuum phenomenon in all dogs, chondrodystrophic, non-chondrodystrophic dogs and those with unknown classification was 19·8, 14·9, 35·7 and 24·5%, respectively. Corresponding correlation rate between vacuum phenomenon and herniated disc was 64, 67, 40 and 82%. Prevalence of vacuum phenomenon was significantly higher in nonchondrodystrophic dogs (P=0·04). Age was the only factor influencing prevalence of vacuum phenomenon (P=0·04).

CLINICAL SIGNIFICANCE

In dogs with intervertebral disc disease, vacuum phenomenon is a frequent but inconsistent finding. Although helpful to identify degenerated discs, it is not suitable to identify currently herniated disc with sufficient accuracy.

[Multiphasic contrast-enhanced CT: correlation of the peak attenuation in the aorta abdominalis and portal vein with easily detectable clinical parameters]

OBJECTIVE

The diagnostic value of a multiphase CT strongly depends on the correct timepoints of analysis. Therefore, we investigated whether the peak attenuation time in the aorta and portal vein are predictable using easily detectable clinical parameters. Regression equations were developed that enable an approximate prediction of these scan times.

MATERIAL AND METHODS

Contrast dynamic CT was performed in 39 anaesthetised dogs of different breeds. The heart rate at the onset of the examination, the age and the body weight were documented. The contrast agent Imeron 300® was injected into a cephalic vein at 3 ml/s with 600 mg iodine/kg body weight using an automatic injector and a dynamic axial CT was started at the same time. The peak enhancement time in the aorta (pETA) and portal vein (pETP) were measured.

RESULTS

The mean pETA was 24.5 ± 8.6 seconds and the mean pETP was 43.6 ± 13.4 seconds. There was a strong correlation (r = 0.92) between pETA and body weight in combination with the heart rate, and a moderate correlation (r = 0.66) between pETP and body weight in combination with the age. The regression equation was: pETA = 12.23 + 0.61 body weight - 0.07 heart rate. The time between pETA and pETP was 8-24 seconds in 34 animals.

CONCLUSION

To plan the arterial peak the authors recommend the use of the established regression equations based on the statistical results or alternatively bolus tracking to plan the arterial peak. When it is planned to examine the portal venous peak, an interscan duration of 8-14 seconds is recommended.

[Comparison of projection radiography and computed tomography for the detection of pulmonary nodules in the dog and cat]

OBJECTIVE

The aim of our study was to evaluate the value of projection radiography as a standard screening method for the detection of lung nodules compared to computed tomography (CT). Furthermore, we attempted to describe the reasons that might lead to a failed detection of pulmonary nodules in radiography.

MATERIALS AND METHODS

From dogs and cats which were diagnosed in CT (multislice CT) with nodular changes in the lung pattern we selected radiographs (projection radiography with soft copy reading) in at least two projection planes produced in the same timeframe as the CT images. Exclusion criteria were nodules > 3 cm and homogenously calcified nodules (osteomata). A total of 70 animals (50 dogs and 20 cats) met the inclusion criteria.

RESULTS

In 43 animals (61%), nodular changes had already been detected using radiography and were then confirmed by the results of the computed tomography. In detail, 32 of 50 dogs (64%) and 11 of 20 cats (55%) showed nodular lesions in the radiographs. In cats, undetected nodules were often accompanied by highly changed lung opacities, resulting in a poor contrast of the lung. In dogs the reasons for a failed detection of lung nodules were relatively equally distributed to several causes. Interestingly, small nodule size itself was not the predominant reason for missing the nodules in radiographs.

CONCLUSION AND CLINICAL RELEVANCE

In general, radiography still plays an important role as a screening method for the detection of nodular lung lesions. However, one needs to be aware, that a quite high percentage of nodular lung changes can be missed in radiographs. The overall detection rate in this study was 61%. Furthermore, we showed that plane radiographs are of poor diagnostic value when concurrent problems exist which lead to increased lung opacity.

Effect of ventral slot procedure on spinal cord compression in dogs with single static intervertebral disc disease: preliminary findings while evaluating a semiquantitative computed tomographic myelographic score of spinal cord compression

OBJECTIVE

To (1) evaluate pre- and postoperative cervical spinal cord compression (SCC) in the context of uncomplicated ventral slot (VS) decompression using computed tomographic (CT) myelography and (2) report reliability of a semiquantitative SCC score using CT myelography.

STUDY DESIGN

Prospective and retrospective, clinical pilot study.

ANIMALS

Dogs (n = 17) with single static intervertebral disc disease.

METHODS

On matched pre- and postoperative transverse CT myelographic images, degree and lateralization of extradural SCC were scored by 4 blinded independent observers, followed by consensus finding. Inter- and intraobserver variability was quantified using intraclass correlation (ICC). Nonparametric tests were performed comparing pre- and postoperative SCC, correlation with neurologic status and significance of lateralization.

RESULTS

Because of invisible contrast agent, only 13 dogs could be fully evaluated. After VS, SCC was significantly reduced whereas neurologic function significantly improved. Ten dogs had residual compression, not affecting neurologic long-term outcome. Only preoperative compression score and neurologic status 3-7 weeks postoperatively were inversely correlated. Lateralization of SCC preoperatively did not affect postsurgical compression scores. Interobserver ICC was 0.848 and intraobserver ICC was 0.984.

CONCLUSIONS

VS improves neurologic function but often fails at completely resolving extradural SCC. The proposed CT myelographic score is highly reliable, assuring consistency among and within observers.

Rhinolithiasis in two miniature dogs

This case report describes two dogs, a Chihuahua and a Pekingese each with rhinolithiasis. Both dogs were presented with chronic nasal obstruction and discharge. Rhinoliths were noted on computed tomography scans in both animals, and removed via endoscopic extraction in one case and laser-assisted endoscopic surgery in the other. The stone from the Chihuahua comprised calcium carbonate. A potential exogenous nidus in the form of plant material was identified in the Pekingese. To the authors' knowledge, this is the first report of rhinolithiasis in veterinary medicine.

Diagnostic yield and adverse effects of MRI-guided free-hand brain biopsies through a mini-burr hole in dogs with encephalitis

BACKGROUND

The diagnosis of encephalitis is usually presumptive based on MRI, cerebrospinal fluid analysis, or both. A definitive diagnosis based on histopathology, however, is required for optimizing treatment strategies.

OBJECTIVE

To investigate the diagnostic yield and adverse effects of minimally invasive brain biopsies in dogs with encephalitis.

ANIMALS

Seventeen dogs with suspected encephalitis, based on MR imaging and cerebrospinal fluid analysis.

METHODS

Retrospective study. Minimally invasive, free-hand brain biopsy specimens were taken from forebrain lesions through a 4-mm burr hole using a Sedan side-cutting needle. Routine histopathological examination was performed. The adverse effects were assessed by MRI evaluations after biopsy procedure (12/17) and by sequential neurological examinations.

RESULTS

The overall diagnostic yield with regard to a specific type of encephalitis was 82%. Encephalitis was evident in an additional 12%, but a specific disease could not be determined. There were no deaths caused by the biopsy procedure itself, but the indirect case fatality rate was 6%. Morbidity was 29%, including stupor, seizures, tetraparesis, hemiparesis, ataxia, and loss of conscious proprioception. All these signs resolved within 3-14 days.

CONCLUSIONS AND CLINICAL IMPORTANCE

Minimally invasive brain biopsy in dogs with suspected encephalitis leads to a definite diagnosis in the majority of dogs, allowing for a specific treatment. The advantages of a definite diagnosis outweigh potential case fatality rate and temporary neurological deficits.

Cholesteatoma after lateral bulla osteotomy in two brachycephalic dogs

This report describes a French bulldog and a pug that presented to the authors' hospital following total ear canal ablation (TECA) and lateral bulla osteotomy (LBO), with signs of recurring otitis media and difficulty opening their mouths. The bulldog also had unilateral facial paralysis and sensory deficits of the trigeminal nerve on the ipsilateral side. Computed tomography and MRI scans suggested cholesteatoma in the bulldog, but showed only slight enlargement of the bulla in the pug. Histopathologic examination of samples yielded cholesteatoma in both cases. The authors suspect that development of the cholesteatomas was linked to the TECA/LBO surgery in both cases. Cholesteatomas may occur more frequently than currently thought. Even if only slight changes of the bulla wall are detected on CT, early-stage cholesteatoma should be considered. The narrow anatomic conditions in brachycephalic dogs possibly predispose such breeds to develop cholesteatoma after middle ear surgery because complete removal of all inflammatory and epithelial tissue can be more difficult than in other breeds. To the authors' knowledge, this is the first report of an aural cholesteatoma causing sensory deficits of the trigeminal nerve.

Oculocardiac Reflex in a Dog Caused by a Choroidal Melanoma with Orbital Extension

A 7 yr old mixed-breed dog was presented with a choroidal melanoma of the left eye that had penetrated the sclera, producing an orbital mass. Bradycardia was detected on auscultation. The bradycardia resolved after exenteration of the orbit and was therefore presumed to be associated with the oculocardiac reflex.

[Magnetic resonance imaging and ultrasonography in dogs and cats with ocular and orbital diseases. Part 1: Ocular diseases]

OBJECTIVE

This two-part study describes the clinical usefulness and value of ultrasound and magnetic resonance imaging (MRI) in dogs and cats with ocular (n=30) and orbital diseases (n=31). MRI and ultrasonography characteristics are described in single cases with ocular and orbital disease.

MATERIAL AND METHODS

Ultrasonography and MRI were performed in 15 dogs and 15 cats with intraocular neoplasia or intraocular inflammatory disease.

RESULTS

In all patients with intraocular neoplasia, sonography revealed masses with increased echogenicity and fairly uniform echotexture, thus allowing the tentative diagnosis of an intraocular tumour. In these cases, MRI often proved to be a valuable diagnostic tool in showing the complete extent of intraocular lesion. An additional benefit of MRI was seen in the tissue characterization of tumours based on MRI signal characteristics and pattern of contrast enhancement. Discreet intraocular inflammatory alterations, in particular to the anterior and posterior segment of the eyeball, were more clearly shown by ultrasound than by MRI. Neoplasia could be excluded and inflammatory disease was successfully diagnosed using MRI due to the different image sequences with or without contrast medium administration. Traumatic ruptures of the lens capsule and the globe after trauma were depicted more clearly with MRI.

CONCLUSIONS AND CLINICAL RELEVANCE

When opacity of the anterior eye segment is present, various intraocular changes can be quickly diagnosed by ultrasound with high accuracy, without requiring anaesthesia of the patient. MRI of the globe allows differentiation of diverse pathologies, gives detailed information of infiltration in orbital structures and the exact degree of ocular lesions after trauma. This additional evidence often makes it easier to predict the correct prognosis and choose the best therapy.

[Liver abscess in a dog. A case report]

The presented case report describes diagnostic and therapy of a liver abscess in a male Golden Retriever dog. The dog was adversely affected by fever, apathy, and vomitus. Diagnostic imaging including radiography, sonography and computed tomography, revealed an abscess-forming lesion of 10 × 5 cm in the left middle liver lobe with detectable multiple gas accumulation within the lesion. The surgical therapy included lobectomy with adjacent omentopexy. Four days after the operation the dog was discharged in a good general condition and with physiological body temperature. Detecting multiple gas accumulation in circular, inhomogeneous lesions by sonography allowed confirmation of the diagnosis. Surgical removal of the affected liver lobe led to recovery of the patient. In human medicine, less invasive methods are preferred, e.g. percutaneous drainage and alcoholization of the lesion. Exclusive medicamentous therapy yields the worst outcome in humans.

[Sonographic examination of the soft palate in dogs]

PURPOSE

The aim of this study was to characterize the normal sonographic anatomy of the soft palate in dogs.

MATERIALS AND METHODS

The study was performed on seven canine heads via a submental and intraoral approach. The detected anatomical structures were then reexamined via a submental approach in a water bath. Each anatomic layer was subsequently dissected starting with the submental layers and working towards the soft palate. After every preparation a sonographic examination was carried out.

RESULTS

Differentiation between the soft palate and the surrounding oropharyngeal tissue can be effectively achieved. Using the submental approach, the transition between hard palate and soft palate as well as the middle section of the soft palate were distinguished from other oropharyngeal structures in all cases. Visualization of the caudal part of the velum and evaluation of the echogenicity of the soft palate were difficult and not always possible. In the two brachycephalic dogs of the study, it was challenging to distinguish the soft palate from the surrounding tissue.

CONCLUSION

The sonographic appearance of the canine soft palate in cadavers was described in this study. The submental approach allows differentiation between intraoral structures. Evaluation of the echogenicity and length of the soft palate is limited.

Computed tomographic-dacryocystography (CT-DCG) of the normal canine nasolacrimal drainage system with three-dimensional reconstruction

The aims of the study were (1) to quantify the influence of selected imaging parameters on the image quality (slice thickness, mAs, and beam orientation) defining optimal conditions for scan protocols and (2) to evaluate the benefits of the 3D reconstruction techniques for visualization of NDS structures in dogs. CT-DCG was performed bilaterally in 32 heads of dogs. CT transverse images were obtained using a combination of two slice thickness values (0.8 mm and 2 mm) and two mAs values (50 mAs and 300 mAs). Two beam projection orientations were also tested: transverse plane (perpendicular to the hard palate) and oblique to the hard palate. Three-dimensional images were obtained using Volume Rendering (VR). Transverse beam projection proved to be superior for the assessment of the inferior and superior lacrimal canaliculi and lacrimal sac. In this study, there was no statistical difference regarding mAs values (50 mAs and 300 mAs) and slice thickness values (0.8 mm and 2 mm). Three-dimensional images were helpful for the assessment of topographic relationship between nasolacrimal structures and cranial landmarks.

[Comparison of different applications of the sonographic contrast medium Levovist]

The influence of the application modes (bolus injection, infusion) of the sonographic signal enhancers Levovist was investigated in a total of 24 dogs. The animals in the bolus group were given 0.2 ml/kg body mass Levovist at a concentration of 300 mg/ml while in the other group the same amount was continuously injected over a time of two minutes. Signal enhancement was measured by an audiodoppler. Contrast duration above six, twelve, 18 and 24 dB and maximum signal enhancement were determined for each application mode. The comparison of these parameters showed that a statistically significant longer contrast duration (significance level p less than 0,05) at 0 and 6 dB can be achieved by continuous injection. Bolus application, on the other hand, resulted in significantly higher maximum contrast enhancement. With time consuming investigations (perfusiondiagnostic, shuntdiagnostic) the contrast effect can be partly extended with continuous injection but the technical requirements are higher and there is the risk that the acoustic properties of the microbubbles are negatively influenced.

[Computed tomography imaging of the temporomandibular joint in dogs and cats. Effects of different scan parameters on image quality]

OBJECTIVE

Temporomandibular joints (TMJs) of dogs and cats were examined with multislice computed tomography (MSCT) using different technical scan parameters in order to investigate their impact on image quality. Another aspect was to analyze whether size differences of the TMJ affect the display of small joint structures.

MATERIAL AND METHODS

The TMJs of two dogs and two cats were examined using MSCT. Scan parameters were varied including tube current, scan matrix, resolution mode, slice thickness, and reconstruction increment. Three observers being blinded with respect to the used scan parameters independently assessed the image quality in terms of "contrast resolution", "bone structure", "spatial resolution", "evaluation of the joint space", and "artefacts" according to a 4-point scale.

RESULTS

The criteria "spatial resolution" and "evaluation of the joint space" emphasize the influence of the size of the TMJ. The image quality of the TMJ of the dogs was evaluated superior (by 0.5 to 1.5 points higher graded) compared to the smaller ones of the cats. In terms of "spatial resolution" and "bone structure" the images of an ultra high resolution technique achieved a higher evaluation level (scoring one point superior) compared to the images created by a high resolution protocol. The tube current did not significantly influence the image quality in any of the pictures.

CONCLUSIONS AND CLINICAL RELEVANCE

The display quality of small structures of the TMJ is dependent on the spatial resolution of the CT images. Therefore, a thin slice collimation, a small field of view, and a high resolution reconstruction matrix should be used. Under those aspects subtle alterations of bone structure of the TMJ can be reliably detected. The soft tissue structures of the TMJ can not be visualized with MSCT in small animals. In principle, the results can be applied to any other MSCT-scanner. However, adjustments of the technical parameters may be still necessary.

[Magnetic resonance imaging of the temporomandibular joint in dogs and cats. Effect of different coils on image quality]

OBJECTIVE

In magnetic resonance imaging (MRI) the image quality is considerably affected by the coil used, particularly when small structures are examined. The purpose of this study was to determine which coil provides the best scanning results for imaging of the temporomandibular joint (TMJ) of dogs and cats.

MATERIAL AND METHODS

MRI investigations were performed using a standard human knee coil and an 8-cm-diameter surface coil with a low-field MRI-system (field strength 0.5 T). TMJs of two dogs and two cats were examined. The scan protocol consisted of T1-weighted spin echo (T1W/SE), T2-weighted turbo spin echo (T2W/TSE), a proton density-weighted sequence (PDW) (slice thickness: 3 mm each), and gradient echo sequences (slice thickness: 1-1.5 mm) in the sagittal plane. Three observers independently compared the features "contrast resolution", "bone structure", "spatial resolution", and "signal-to-noise ratio" (SNR) using a 5-point scale. Investigators were blinded with respect to the coils used.

RESULTS

Approximately 50% of the images obtained by the use of the surface coil were rated superior in comparison with the knee coil in terms of the features "contrast resolution", "bone structure", and "spatial resolution". In approximately 50% of the MRI-images no differences in the ratings were seen. With respect to the criterion "signal-to-noise ratio" 90% of the images acquired with the surface coil were rated better. In 5% of the images an identical quality was recorded. The surface coil proved to be superior both in dogs and cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Display quality of small structures of the TMJ is dependent on the spatial resolution of the MR images. Therefore, a dedicated coil and a small field of view (FOV) should be used. Results reveal that low-field MRI is able to display subtle anatomic structures of the TMJ in dogs and cats. In principle, the results can be transmitted to other MRI-systems. However, to generate valid scan protocols it is necessary to adapt scan parameters and coil selection specifically.

Display quality of different monitors in feline digital radiography

In human medical imaging, the performance of the monitor used for image reporting has a substantial impact on the diagnostic performance of the entire digital system. Our purpose was to compare the display quality of different monitors used in veterinary practice. Two medical-grade gray scale monitors (one cathode-ray tube [CRT], one liquid crystal display [LCD]) and two standard consumer-grade color monitors (one CRT, one LCD) were compared in the ability to display anatomic structures in cats. Radiographs of the stifle joint and the thorax of 30 normal domestic shorthair cats were acquired by use of a storage phosphor system. Two anatomic features of the stifle joint and five anatomic structures of the thorax were evaluated. The two medical-grade monitors had superior display quality compared with standard PC monitors. No differences were seen between the monochrome monitors. In comparison with the color CRT, the ratings of the color LCD were significantly worse. The ranking order was uniform for both the region and the criteria investigated. Differences in monitor luminance, bit depth, and screen size were presumed to be the reasons for the observed varying performance. The observed differences between monitors place an emphasis on the need for guidelines defining minimum requirements for the acceptance of monitors and for quality control in veterinary radiography.

[Effects of a neuroleptic analgesia with acepromazine on the blood perfusion of the canine kidney. Examination using the sonographic recordable blood circulation parameters of resistance index and pulsatility index]

OBJECTIVE

Kidney failure after anaesthesia constitutes a serious clinical complication. A number of patients suffer from compensated kidney insufficiency, which may be transformed into an acute kidney insufficiency through additional stress, such as an operation and anaesthesia. The aim of the present study was to investigate the effects of a neurolept analgesia with acepromazine on sonographically accessible blood perfusion parameters.

MATERIAL AND METHODS

Following anaesthesia with acepromazine/l-methadone (0.1 mg/kg BW acepromazine, 0.5 mg/kg BW l-methadone) a sonographic examination of the left kidney was performed in 19 clinically healthy foxhound and beagle dogs. Every 5 minutes resistance index and pulsatility index as well as invasive blood pressure were measured and digitally recorded.

RESULTS

Within 5 minutes after induction of anaesthesia a transient increase of the mean arterial blood pressure occurred. After 10 minutes the blood pressure decreased to the initial value and remained essentially constant to the end of the investigation. Resistance index and pulsatility index showed a similar behaviour: After a small initial decrease during the first 5 minutes both parameters displayed a significant increase. This rise was very pronounced up to approximately 15 minutes and then flattened significantly until the end of the test period after 30 minutes. The values corresponded to those found in vessel stenosis.

CONCLUSION AND CLINICAL RELEVANCE

Due to the described changes this type of anaesthesia should not be used in dogs with nephropathy, even though the results of this experimental study might not be necessarily transferable to the clinical patient.

Partial lateral corpectomy of the thoracolumbar spine in 51 dogs: assessment of slot morphometry and spinal cord decompression

OBJECTIVE

To report slot morphometry, degree of spinal decompression, and factors influencing decompression after partial lateral corpectomy (PLC) of the thoracolumbar spine in dogs with intervertebral disc disease.

STUDY DESIGN

Case series.

ANIMALS

Dogs (n=51) with predominantly ventrally located spinal cord compression.

METHODS

PLC (n=60) were performed. Spinal cord compression was determined by computed tomographic (CT) myelography (n=46), myelography (n=2) or magnetic resonance imaging (n=3). Postsurgical CT images were used to evaluate slot dimensions and orientation, and spinal cord decompression. The influence of age, body weight, breed, breed type (chondrodystrophic, nonchondrodystrophic), disc location, lateralization and mineralization, presurgical compression, slot morphometry, and surgeon on degree of decompression were evaluated.

RESULTS

Mean slot depth was 64.1% of vertebral body width; mean height, 43.0% of vertebral body height; mean cranial extension, 29.5%; median caudal extension, 22.0% vertebral body length; mean angulation from horizontal, 6.3°. Decompression was satisfactory in 90% of sites after PLC (58% complete, 32% good). None of the analyzed factors significantly influenced decompression. All lumbar spine PLC resulted in complete or good decompression compared with 83% after thoracic PLC (P=.052). Deeper slots tended to allow more complete decompression (P=.058).

CONCLUSIONS

Thoracolumbar PLC results in satisfactory decompression in most cases with a better outcome in the lumbar spine than the thoracic spine. Achieving a slot depth equal to 2/3 of vertebral body width might facilitate complete decompression.

[Dose measurement in small animal radiology: how intense is the influence of distance and position of the investigator in relation to the patient?]

Radiation exposure of body parts of persons, needed to restrain small animal during the examination, varies depending on the distance and position in relation to the patient, the region investigated, and the exposure settings applied. The aim of the study was to quantify the effects of these factors on the ambient dose. The dosimeter was positioned with varying distance from the direct beam (from 30 to 150 cm) and on different level above the floor (55 cm, 85 cm, and 150 cm. The study consisted of two parts. In the first part a plastic water tank (thickness: 18 cm) was used as source of scatter radiation. Different exposure settings (77 kVp; 20 - 10 - 5 - 2.5 - 1.25 mAs) were applied. In the second part dose was measured during the examination of the abdomen of a large dog (thickness: 18 cm; 77 kVp, 20 mAs) and of the skull of a cat (thickness: 6 cm; 55 kVp, 20 mAs). At the level of the patient (85 cm above the floor) the dose decline relative to the distance followed a quadratic function. In the series "abdomen-dog" the mean dose values ranged from 51.6 microSv (30 cm distance) to 1.02 microSv (150 cm distance). The corresponding doses for the series "skull-cat" were 0.98 microSv and 0.02 microSv, respectively. Comparably lower doses were measured on the lines along the table, when non-irradiated parts of the body were located between the exposed patient volume and the dosimeter. At 150 cm above the floor higher doses were observed relative to the doses at the level of the table. The following conclusions can be drawn: (1.) Depending on the target volume the ambient dose varies in a wide range. (2.) An increase of the distance of only few centimetres is reducing exposure considerably. Therefore persons should make use of it whenever this is possible. (3.) Persons should stand on the short sides of the table while fixing the patient. (4.) Head and neck are relatively highly exposed. Methods to protect the thyroid gland and the eye lens are indicated. (5.) Since different exposure levels can be applied in digital radiography, the range of dose levels is rather wide. Therefore strict dose discipline (e.g. by use of exposure tables and dose indicators) is necessary to avoid continuing overexposure.

Development and in situ application of an adjustable aiming device to guide extra- to intraarticular tibial tunnel drilling for the insertion of the cranial cruciate ligament in dogs

OBJECTIVE

To develop and test an arthroscopic aiming device for extra- to intraarticular tibial tunnel drilling emerging at the center of the tibial insertion (CenterTib) of the cranial cruciate ligament (CCL) in medium to large breed dogs.

STUDY DESIGN

Descriptive experimental study.

SAMPLE POPULATION

Fifty-two cadaveric hind limbs of dogs >or=20 kg BW.

METHODS

The mediolateral position and craniocaudal position (ccPos) of CenterTib in relation to the caudomedial meniscotibial ligament were measured on photographs of 46 dissected tibial plateaus. The proximal tibial depth (TibDepth) was determined on lateral radiographs and its correlation with ccPos was assessed using linear regression analysis. Extra- to intraarticular arthroscopic tibial tunnel drilling was performed in 6 independent cadaveric stifles. A C-guide with an adjustable craniocaudal offset was constructed and adjusted according to ccPos estimated based on TibDepth. The position of the resulting bone tunnels was compared with the position of the CenterTib.

RESULTS

Pearson's correlation between TibDepth and ccPos was strong (R=0.86; P<.001). ccPos (y) as a function of TibDepth (x) can be expressed as y=-4.8+0.3x. Arthroscopic tunnel drilling resulted in a median deviation of the drill tunnels around the CenterTib of 1 mm.

CONCLUSION

The regression equation and aiming device permit localization and targeting of CenterTib during extra- to intraarticular tibial bone tunnel drilling in vitro.

CLINICAL RELEVANCE

The proposed technique may reduce tibial tunnel misplacement when performing intraarticular CCL repair using a tibial bone tunnel.

[Radiographic location of the tibial cranial cruciate ligament attachment in middle- to large breed dogs]

OBJECTIVE

Investigation of the radiographic cranio-caudal (cc) and medio-lateral (ml) location of the tibial centroid of the attachment area of the CCL (ACCL).

MATERIAL AND METHODS

In 46 tibiae from orthopedically healthy dogs (22-50kg) the tibial plateau was stripped of all soft tissue, degreased with acetone and the contour of the ACCL was marked with ink stain. The CCL was completely resected and one pin each was placed at the most medial, lateral, cranial and caudal extensions of the ACCL. On digital images of each tibial plateau the previously marked contour of the ACCL was traced. Using custom-made image analysis software the two-dimensional centroid of the ACCL was determined and transferred to standard radiographs in two planes of each tibia. The cc location of the centroid of the ACCL was measured starting at the intercondylar tubercles. The proximal tibial extension (TibEx) was obtained and linear regression analysis was applied to develop a mathematical first order equation for the calculation of the cc location of the centroid based on the proximal tibial depth in the individual stifle. The ml location of the centroid was measured in relation to the medial intercondylar tubercle.

RESULTS

A statistically significant (p<0.001) correlation was found between the TibEx and the anatomical cc location of the centroid. Linear regression analysis revealed a first order linear equation for calculation of the individual cc location of the centroid in mm to be: 0.28 x TibEx - 4 in mm with an R2 of 0.83. The median ml location of the centroid in relation to the medial intercondylar tubercle was 0mm whereas 90% were located 1 mm medial and 1 mm lateral to the medial intercondylar tubercle.

CONCLUSION

The radiographic location of the centroid of the ACCL can be individually determined on standard stifle radiographs.

CLINICAL RELEVANCE

With the help of these data the location of a tibial drill tunnel in anatomic reconstruction of the ruptured CCL may be evaluated either intra-operatively with fluoroscopy or postoperatively on two plane standard stifle radiographs and the placement could be corrected when necessary.