Planar bone scintigraphy and CT findings in dogs with forelimb lameness

Scintigraphy has been used for many years in veterinary medicine, due to its high sensitivity, for the localization of lameness of unknown origin in horses and for the assessment of thyroid/skeletal neoplasia in dogs. In the last few years bone scintigraphy (BS) has become increasingly used in dogs for the localization of occult lameness, when clinical examination and radiographic exam are inconclusive [1]. This study describes BS and computed tomographic (CT) findings in dogs referred for monolateral forelimb obscure lameness, for which a precise localization had not been found by clinical examination nor radiographic exam (no abnormalities at all, mild radiological abnormalities which could not be related to the grade of lameness or symmetrical bilateral alterations). Eight dogs matched inclusion criteria: 3 mixed breed, 1 Bernese mountain dog, 1 Amstaff, 1 Labrador retriever, 1 Australian shepherd and 1 Boxer. BS images showed intense IRU (Increased Radiopharmaceutical Uptake) of elbow joint in 6 cases; these findings coincided to CT alterations of proximal ulna in 5 dogs (mostly located in the medial coronoid process - MCP region: bone density alterations, evidence of fragmentation, new bone formation). In one of these cases, an intense IRU was observed in correspondence of the region of the flexors attachment, with no concurrent abnormalities on CT examination. These findings were suggestive of an obscure form of flexor enthesopathy. In one case we observed diffuse and intense IRU of the carpus joint; this coincided with arthrosis and the presence of a subchondral cyst. One dog showed only mild IRU of the elbow joint, not compatible with the degree of lameness. Because of lack of significant IRU, CT and MRI examination were performed and revealed the presence of an expansive lesion in correspondence of the brachial plexus roots compatible with PNST (Peripheral Nerve Sheath Tumor). BS' high sensitivity allowed the localization of the lameness thanks to the assessment of functional bone state, as already stated in literature [2]. However, its low specificity required additional imaging (CT, MRI), targeted on the region identified on scintigraphic examination. In our experience, the combined use of functional and morphologic diagnostic imaging techniques (bone scintigraphy and computed tomography- magnetic resonance) has been helpful to reach a definitive diagnosis. Further studies, with an increased sample size, are needed to evaluate whether there is a correlation between bone density changes and grade of IRU in limbs affected by different pathologies

Diagnostic value of whole body bone scan in horses

Scintigraphy is widely used in the assessment of musculoskeletal disorders and often it is considered as a screening tool in lame or poor performing horses. It is proved that nuclear scintigraphy is useful in highlighting the presence of lesions undetectable by clinical examination, in horses that do not respond to local analgesic blocks or with intermittent lameness[1]. Despite the usefulness of bone scan is proven, in a recent report, Quiney et al. observed that false-negative results predominate and may lead to missed diagnosis[2]. The aim of this study is to analyze the diagnostic usefulness of whole body bone scan in horses referred for lameness or poor performance. For this retrospective study, bone scans acquired at the Ospedale Veterinario Universitario di Lodi between July 2014 and February 2019 were reviewed. In the study have been included only horses that had a whole body bone scan. On the basis of the history, horses were classified as poor performing, for localized lameness or non-localized lameness. Scintigraphic findings were organized in five categories: definitive diagnosis, localization of the lameness, no findings related to the present clinical signs, findings of unlikely clinical significance and findings that need further investigations. A contingency table and a chi-squared test were used for the statistical analysis. One hundred and eighty horses underwent scintigraphy and 102 were included in the study; twenty-one horses were referred for lameness localized using diagnostic analgesia while in 44 horses the source of lameness was not identified. Thirty-seven horses had an history of poor performance. Statistical analysis highlighted that the only correlation between clinical history and scintigraphic findings was between horse referred for poor performance and findings of unlikely clinical significance (59,5% of horses with a poor performance diagnosis). A final diagnosis or localization of the source of pain were observed respectively in the 5.9% and in the 29.4% of horses. In 11 subjects (10.8%) were found increased radiopharmaceutical uptakes (IRU) of uncertain clinical significant that needed further investigations using analgesic blocks. In the 20% of cases, all referred for lameness, no findings related to the present clinical signs were found. In order to increase the capability of bone scintigraphy, it is mandatory to consider that the sensitivity and specificity are higher in specific regions[2] and the interpretation of the relevance of IRU must be based on detailed clinical examination. In conclusion, we confirm that whole body bone scintigraphy should not be considered a diagnostic screening especially in poor performing horses and that localization of lameness can improve the possibility of a positive result. [1] Dyson S.J. Musculoskeletal scintigraphy of the equine athlete. Semin Nucl Med, 44:4-14, 2014. [2] Quiney L., Ireland J., Dyson S.J. Evaluation of the diagnostic accuracy of skeletal scintigraphy in lame and poorly performing sports horses. Vet Radiol Ultrasound, 59:477-489, 2018

Peribulbar block in equine isolated heads : development of a single needle technique and tomographic evaluation

Peribulbar block (PPB) has been used in humans as a safer alternative to retrobulbar block (RBB). PBB, depends on the diffusion of anaesthetic solution into the muscle across the connective tissue and it is performed introducing the needle within the extraconal space. The advantages are fewer complications and palpebral akinesia. In Veterinary Medicine few studies describe this technique in dogs and cats (Shilo- Benjamini et al., 2013). The aim of the study is to determinate, in equine specimens, feasibility of inferior PBB with single needle injection, by using contrast medium (CM), and to evaluate thought Computed Tomography (CT) the distribution of the injected volume and regional anaesthesia likelihood. PBB was performed in 10 orbits. The mixture injected consisted of 20 ml of physiological solution and iodinated CM at 25%. Each periorbital area underwent three CT scans. A basal acquisition to assess the needle position before the injection, a second and third scan were performed immediately after injection, and after application of pressure on the periorbital surface area to promote CM diffusion. The injectate distribution at the base and within the extraocular muscle cone (EOMC) and around the optic nerve was evaluated and scored based on Shilo-Benjamini\u2019s work of 2017. The mean minimum distance between the tip of the needle and the optic was 2,23 mm \ub10,2. The mean volume distribution before pressure application was 23.56 cm3 \ub1 2.58 and after pressure application was 27.56 cm3 \ub1 4.8. The CM median distribution around the optic nerve at the base of the EOMC was of 117\ub0 prior pressure and 189\ub0 after pressure. The CM distribution within the EOMC was present in 1 orbit prior pressure and in 3 orbits after pressure. The CM distribution at the base of EOMC was considered unlikely to provide regional anaesthesia in 2 orbits, possible in 3 orbits and likely in 5. In the present study, intraconal distribution was not consistent. For this reason, the likelihood of achieving regional anaesthesia was evaluated at the EOMC base where through the optic foramen the oculomotor, trochlear nerve, ophthalmic branch of the trigeminal nerve, and the abducens travel to reach the orbit together with the optic nerve. Whereas the maxillary branch of the trigeminal nerve passes through the foramen rotundum (Carastro 2004). Therefore, despite the lack of intraconal distribution if the EOMC base had good distribution then it was considered likely to provide regional anaesthesia. This approach needs to be evaluated in clinical trials to assess its feasibility and effectiveness in locoregional anaesthesia; moreover, further investigations on equine PBB are mandatory with higher volumes of injectate and different approaches

Cervical cystic lymphangioma in a young dog: CT findings

Lymphangioma is a rare lymphatic disorder; in veterinary medicine it is still considered a benign tumour, while in human medicine has been recently classified as a Lymphatic Malformation (LM), in fact it probably origins from a failure in development of connections between lympatic and venous system. Reported localizations of canine lymphangioma include skin, subcutaneous and fascial tissue of axilla, limbs, inguinal and mammary regions; lymph nodes; retroperitoneal space; nasopharynx. In the present report we describe the computed tomographic (CT) features of a cervical cystic lymphangioma in a young dog. A 1-year-old intact male Italian Shepherd dog was referred to the primary care veterinarian with a 1-month history of left ventrolateral neck swelling. No other clinical signs were present. Ultrasonographic (US) examination revealed a mass with hyperechoic thick wall, hypoechoic content with hyperechoic fluctuating areas. Fine needle aspiration biopsy (FNAB) revealed a cloudy pinkish fluid, citologically referable to serous-hematic fluid with chronic inflamation. For better assessment of the morphology and of the margins of the lesion, the dog was referred for CT examination. Pre- and post-contrast CT scan of head, neck and thorax were made. A mass located between the muscles of the caudal neck and thoracic/axillary regions (from the level of C4 to the level of T2) was found, which partially occupied the left visceral space of the neck and bulged into the thoracic inlet. The mass was ellipsoid-shaped (40x45x140 mm), with well-defined margins and heterogeneous soft tissue attenuation. It was apparently capsulated, with fluid-like content and soft tissue attenuating septa and small areas within the fluid. Adjacent to the mass three areas of soft tissue mineralization, smoothly marginated, were found. It was responsible for mild mass effect, without significant compression on the surrounding structures. Mild left axillary and left medial retropharyngeal lymphadenomegaly was noted, with normal shape and attenuation of the limph nodes. Post-contrast images showed moderate enhancement of the mass wall and the soft-tissue-attenuating areas/septa within it; no enhancement of the fluid was noted. No other abnormalities were found. The mass was completely surgically excised and submitted for histopathologic analysis, with a definitive diagnosis of cystic lymphangioma. In human literature CT features of lymphangioma are widely described, while in veterinary literature there are no reports about its CT appearance; moreover, human lymphangioma is described as preferentially located in the neck and axillary regions, while, to our knowledge, cervical localization has never been reported before for canine lymphangioma

Continuous rate infusion of dexmedetomidine vs subcutaneous administration in anaesthetized horses undergoing MRI examination

Up to 2005, dexmedetomidine use had not been reported in equine. Since then, several experimental and clinical studies have been published. The main reason for this increase relies on its beneficial pharmacological profile, including short half-life and rapid redistribution (1). The aim of the study is to compare the clinical effects and recovery quality after continuous rate infusion (CRI) or subcutaneous administration of dexmedetomidine in horses undergoing general anaesthesia. Fourteen horses scheduled for MRI examination were included. All horses were sedated with acepromazine 0.03 mg kg-1 intravenously (IV) and detomidine 10 \ub5g kg-1 (IV). Anaesthesia was induced with ketamine 3 mg kg-1 (IV) and diazepam 0.04 mg kg-1 (IV) and maintained with isofluorane in 60% oxygen; end-tidal isoflurane concentration was maintained between 1.3-1.4 %. Horses were randomly divided in two groups. Group \u201cDex CRI\u201d received dexmedetomidine intravenously at 1 \ub5g kg-1 hour-1, group \u201cDex SC\u201d received 2 \ub5g kg-1 of dexmedetomidine subcutaneously every 60 minutes. If nystagmus or incessant fighting against ventilator occurred, ketamine rescue at 0.1 mg kg-1 was given. In case of sudden movements, thiopental 0.5-1.0 mg kg-1 IV was given. Ringer\u2019s lactate was given at 3 mL kg-1 hour-1, dobutamine was administered IV and the rate adjusted to maintain MAP>70 mmHg. Controlled mechanical ventilation using intermittent positive pressure ventilation was adjusted to maintain arterial carbon dioxide partial pressure between 38-45 mmHg. Heart rate, invasive arterial blood pressure, arterial blood gases, total dose of dobutamine administered, ketamine rescue needed, urine production were recorded. Time required until extubation and time to attain sternal and standing position were noted. The main anaesthesiologist assessed recovery quality graded on a standard scoring 5-point scale with a score of 1 representing the best recovery (2). Mann-Whitney U test was applied for non-parametric data and T-test for parametric data (p 640.05). There was no statistically differences in physiological intra-anaesthetic parameters, in body weight (kg) (CRI 521\ub153; SC 506\ub176), age (years) (CRI 10.7\ub12.1; SC 10.8\ub14.1), anaesthesia duration (min) (CRI 139\ub19.,7; SC 144\ub116.2), number of ketamine rescue needed (CRI 1\ub11.15; SC 0.5\ub11.13), recovery score (CRI 1.8\ub11,2; SC 1.5\ub10,5). Also time until extubation (min) (CRI 11.5\ub15.0; SC 9.7\ub12.6), time to attain sternal (min) (CRI 41.5\ub112.2; SC 49.7\ub16.0) and standing position (min) (CRI 50.7\ub114.6; SC 57.2\ub16.,0) were not statistically different. There was statistical significance in urine production (L) (CRI 8.0\ub13.5; SC 11.1\ub14.4) and total dobutamine mcg/kg/min (CRI 0.89\ub10.35; SC 0.56\ub10.18). Subcutaneous administration of dexmedetomidine has product similar clinical effects to those achieved with CRI. It has permitted a significative reduction in dobutamine administration and a more stable depth of anaesthesia confirmed by the lower number of rescue ketamine boluses required even if not statistically different. Further studies are required to evaluate different dosages both in CRI and subcutaneous administration

The Frankenstein horses : clinical and diagnostic imaging findings in horses with suture line periostitis

Swellings of the equine frontal area can be caused by inflammation of the craniofacial sutures. Suture line periostitis (colloquial term \u201csuturitis\u201d) results in a firm, usually non-painful swelling in the nasofrontal, maxillary and zygomatic region accompanying epiphora. Instability of the craniofacial suture lines, facial trauma and surgical sinusotomy could be predisposing factors. A definitive diagnosis can be reached with radiography and computed tomography (CT). This study describes clinical, CT and radiographic findings of craniofacial suture lines periostitis in two horses with facial swelling. Two horses developed craniofacial suturitis and were presented with a moderate painful facial swelling, epiphora and mild hyperthermia. A 10 year old, Italian saddle horse, gelding developed clinical manifestation after sinuscopy and positioning of a Foley catheter in the conco-frontal sinus for local treatment of a micotic sinusitis. A 16 year old, Wielkpolska, stallion, developed symptom after frontal synusotomy for the removal of a cystic mass in the left maxillary sinus. A latero-lateral radiographic view of the head in the first horse allowed to recognize bony proliferation, sclerosis and periosteal new bone formation on both sides of the nasofrontal suture. Computed tomography findings in both horses consisted in an intense, irregular periostal thickened bony wall that affected the frontal, lacrimal, zigomatic and maxillary bone. In one case, there was a necrotic bone sequestrum upon the nasofrontal suture line, not detectable on radiographic views. In the second case, the reaction was more intense near the cerclage wires used to fix the nasofrontal flap associated with osteolysis. In both cases the diagnosis was suture lines periostitis. Horses were treated with surgical removal of the necrotic sequester in the first case and the removal of the cerclage wires of the nasofrontal flap in the second one. Sample materials were submitted in both cases for a microbiologial testing and resulted sterile. Horses were administered anti-inflammatory drugs for one week with improvement of the clinical signs. At the 30 weeks follow-up, the owners reported that the nasofrontal swelling and epiphora were no longer detectable. In conclusion, suture line periositits should be included in the differential diagnosis in case of facial swelling expecially in horses underwent to sinus surgery or after an head trauma. In our cases, CT allowed a more accurate assessement of the bony structure and identification of the underlying causes of inflammation

The use of computed tomography in the diagnosis of traumatic acetabular fractures in a colt

Pelvic fractures are uncommon in horses even if a predisposition in female horses less than 2 years old is reported in literature. Fractures involving the acetabulum are related to a trauma, often a fall. A definitive diagnosis can be reached by standing radiography, ultrasonography, computed tomography (CT), scintig- raphy and diagnostic arthroscopy. This case report describes the radiographic and CT findings in a colt with an acetabular fracture. A five month old Barockpinto colt was referred for an acute severe lameness of the left hindlimb of 3 weeks of duration. The colt was treated by the referring veterinary surgeon with phenylbutazone and box rest for one week with a mild improvement of the lameness. At presentation , the colt showed good body condition and clinical parameters were in normal range. A moderate swelling on the left coxofemoral region was noted. The colt was lame at walk and the abduction of the limb induced a moderate pain. The colt was sedated with alpha2-agonist and latero-lateral and ventro-dorsal radiographic obique views of the hip were taken with the horse in standing position The colt underwent CT of the pelvis in dorsal recumbency, under general anesthesia. Radiographic examination revealed a left coxo-femoral dias- tasis, irregular margins of the acetabulum associated with radiolucent areas and subchondral sclerosis of the fovea capitis. Computed tomography findings consisted in multiple fractures involving the dorsal acetabular margin in association with dorso-cranio-lateral dislocation of the femoral head. In proximity of the caudo- ventral aspect of the acetabular fossa were present several small mineralized fragments. Moderate sclerosis was seen in the fovea capitis and a mild osteopenia of the left femoral head. Despite the radiographic views allowed to recognize the presence of a femoral head luxation and irregularities of the acetabular margings, only CT images revealed the presence of multiple fractures along the acetabular rim improving the prognos- tic value for the patient. Compared with radiography in dorsal recumbency with the limbs in a frog-legged posture, extended positioning of hindlimbs used fot the CT acquisition, induced less stress on the fracture3 In conclusion, on the basis of our experinece and in accordance with other studies, CT examination provides more valuable information than radiographs in the diagnosis of the coxo-femoral joint disease

Contrast enhanced magnetic resonance imaging of the foot in horses using intravenous versus regional intraarterial injection of gadolinium

The use of contrast enhanced magnetic resonance imaging (MRI) for the detection of orthopedic pathologies in equine patients is poorly described. In few studies, enhanced MRI allowed to differentiate active lesions from chronic ones and to classify ambiguous lesions. The aim of this clinical prospective pilot study is to describe and compare the MRI lesions observed in horses with lameness localized to the foot using a single intravenous bolus dose of gadolinium contrast versus regional intraarterial bolus of contrast agent. Ten horses that underwent contrast enhanced MRI were included in the study. Gadolinium was injected intravenously in 3 patients and in 7 horses contrast agent was administered by intraarterial regional delivery. Regions of interest (ROI) were collected from both pre- and post- contrast images and ratios between pre- and post-contrast ROIs were calculated. No adverse reactions were noted after contrast agent injection. Injured structures that revealed greater increase in signal in post-contrast images were the deep digital flexor tendon (DDFT), the navicular spongiosa and the peritendinous tissues. Regional intraarterial administration of gadolinium provided higher ratio of contrast enhancement. Enhanced MRI using both intravenous or intraarterial injection of gadolinium, increased the diagnostic capability of MRI in horses with foot lesions. Nevertheless, regional intraarterial administration of gadolinium was considered the best choice due to the higher signal and lower volumes of contrast agent required

Standing Computed Tomography (CT) in the equine patient

Computed tomography (CT) allows a better evaluation of the equine skull than conventional radiographs, providing excellent contrast and spatial resolution. The availibility of CT examination in the equine prac- tice is often limited by the need of general anesthesia and procedure high costs. To avoid the anesthetic complications and reduce the overall cost of the procedures, custumized CT scanners for standing equine patients examination have been developed. The aim of this study is to describe the CT standing system with particular relevance to acquisition protocols and positioning through the analysis of four clinical cases. In addition, advantages and limitations of the procedure will be investigated. In the study were included 4 horses (age 10-21 years) referred for dental or sinonasal disease that underwent a standing CT examination. A multi-detectors 16 slice CT system was used for the study. The horses were sedated with alpha2-agonist and opioids and positioned standing squarely on an air pallet platform connected to the CT table. Thanks to the air-cushion the friction on the floor was almost nulled allowing to the CT table to pilot the horse into the gantry. The equine head was placed in extended position on the CT table and a weight was put on the neck to minimize its movements during acquisition. Images were acquired in contiguous helical mode with 1,25 mm slice thickness. Scanning parameters were 140 kVp and 300 mA. Duration of each scan was in a range of 30-35 seconds. In one horse a remaining dental fragments of the teeth 209 and the presence of an abscess and necrotic tissues in the caudal maxillary sinus were observed. One month after surgical removal of the fragmented teeth, the CT was repeated because of the presence of monolateral nasal discarge. The follow up CT allowed to recognize the presence of a communication between the oral cavity and the cranial maxillary sinus even if the plug was in situ. In two horses a sinonasal cyst was diagnosed. In one horse, referred for headshacking CT exam revealed: cyst like lesion close to the apex of 106 root, hickening of the right nasal bone, fluid accumulation in the right cranial maxillary sinus and thickening of the mucosa of right dorsal concha. In all horses CT examination was performed easily and without complications and an accurate and definite diagnosis was reached in 75% of cases. Minimal motion artifacts were noted without affecting the diagnostic value. The limited availability of CT scanner for standing horse and the possibility to have motions artifacts are the major problems of this technique. A good sedation protocol and well trained staff is mandatory to obtain good quality images safely both for the patient and the personal. The standing CT examination eliminates the risks of general anesthesia and allows to submit the patients to follow-up CT scans without increasing the risk of morbidity. In addition, performing a CT examination on a standing horse affected by neurological disroders is safer and has the same capability of a CT scan performed on a horse under general anesthesia. Last, but not least, performing CT in standing patients can rather reduce the costs of the examination

Acepromazione, detomidine and morphine: “the wooden horse” evaluation of standing sedation protocols in the equine patients undergoing bone scintigraphy

In equine practice standing sedation has became increasingly popular. Many protocols have been investigated permitting to restrain patients avoiding general anaesthesia and the risk associated by increasing the threshold to all external stimuli and partially providing analgesia (Muir W. 1981; Dodman N. 1980). The target of standing sedation protocols during diagnostic imaging procedures is to reduce all the reaction of the patients to external stimuli, and to diminish physiological movements. No studies have been published establishing a standard protocol, and the decision of which protocol use is based on anaesthetist preferences and not on evidence-based medicine.The aim of the study is to evaluate two sedative protocols, focusing not only on the lack of response to stimuli and the reduction of physiological movements but also on the immobility of the patient that is mandatory for diagnostic imaging procedures.Thirteen horses referred to perform bone scintigraphy were enrolled in the study. Patients were randomly divided in two groups; both groups received same dose of acepromazine (0.003 mg/kg) and detomidine (10 \uf06d/kg), MOR group received morphine (0.25 mg/kg), the BTF group received butorphanol (0.01 mg/kg). During the procedure to evaluate the horse sedation a simple descriptive scale (Taylor P. et al. 2014) was used; respiratory and hearth rate were recorded and if needed adjunctive boluses of detomidine were administrated. To evaluate the reduction of voluntary and involuntary movements the parameter chosen was the number of retake necessary to obtain an image with excellent diagnostic quality. This parameter was evaluated each time by the same radiologist that was unaware of which protocol was administered. Statistical analysis with T-Test was performed.Heart rate resulted not statistically different (MOR=27.1\ub12,4;BTF 26.8\ub13.7); respiratory rate in the MOR group resulted statistically diminished (MOR=9.9\ub12.3; BTF 13.4\ub13.1). The sedation score was statistically higher in the MOR group (MOR= 1.6\ub10.5; BTF 1.0\ub10.3) and moreover in the total body examinations. The total dose of detomidine used in the two groups resulted non statistically different (MOR=23.7; BTF 23.2). The total number of retake did not result statistically significant even if the clinical difference was relevant (MOR=7.1; BTF=16.2), but the number of retake for each region investigated resulted statistically diminished in the MOR group (MOR=0.4\ub10.5; BTF 0.8\ub10.8). The results of this study demonstrate the supremacy of the MOR sedation protocol to perform bone scintigraphy in horses. Further studies are recommended to evaluate the administration of detomidine constant rate infusion to maintain a required sedation degree. The \u201cWooden Ho se\u201d could by applied in ot e diagnostic imaging tec niques suc as CT o MRI and also for various standing surgeries. Other parameters that could be considered are the duration of the exams and also the number of urinations of the patient during the exam to evaluate operators exposure to radiations