Imaging diagnosis and clinical presentation of a Chiari malformation in a Thoroughbred foal

A newborn Thoroughbred foal was presented to the clinic with ambiguous neurological deficits, spinal anomalies and a soft tissue swelling dorsal to the lumbar vertebral column. The foal was alert but unable to rise and stand. With radiography, ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) a lumbar dysraphic anomaly, cerebellar herniation and coincidental skeletal abnormalities were documented. Finally, a meningomyelocele was defined and, in context with the cerebellar herniation through the foramen magnum, the foal was diagnosed to have a Chiari malformation. The MRI examination corresponded best with the post mortem findings. Although 3‐dimensional imaging methods have been considered superior regarding full and detailed assessment of the congenital malformation, radiography and ultrasonography also provide essential information to diagnose dysraphic lesions at reduced costs and efforts. A Chiari malformation should be considered as a differential diagnosis in foals with neurological deficits.     

COMPUTED TOMOGRAPHIC EVALUATION OF HEAD TRAUMA IN A FOAL

This case report describes computed tomographic findings of a three-month-old, 180 kg female Arabian foal that had suffered head trauma. Computed tomography proved valuable in antemortem diagnosis of skull base fracture and extradural hematoma, which were confirmed by postmortem examination.     

Complex stifle injury in a foal

A 130 kg, 60-day-old Quarter Horse male foal presented with bilateral stifle effusion and severe left hindlimb lameness. Clinical examination and imaging including radiography, ultrasound and computed tomography revealed bilateral stifle trauma. Specifically, disruption of the left medial meniscus and deep bone injury to the left medial femoral condyle (MFC) were detected, and bilateral injury to the origin of the cranial cruciate ligaments was suspected. Treatment consisted of stall rest and joint injection with corticosteroids, however there was little improvement in lameness. Due to the poor prognosis for soundness, the foal was subject to euthanasia 10 weeks after initial presentation. Post-mortem examination supported the left medial meniscus and MFC injuries and revealed avulsions of the origin of the cranial cruciate ligaments (complete on the left and partial on the right) from the lateral femoral condyle. Histopathology of the left stifle joint revealed varying depths of MFC osteochondral injury and severe left medial meniscus damage.     

Bullous emphysema with haemorrhage in a premature foal

A Warmblood foal was admitted at one day of age because of prematurity and seizures. Clinical and clinical pathology abnormalities were consistent with prematurity and suspected hypoxic seizures that responded to anti‐convulsive therapy. The foal stabilised after several days of intensive care but then developed an airway infection. Thoracic radiographs showed multiple cavitary lesions and ultrasound examination suggested intra‐cavital haemorrhage. The foal went on to develop septicaemia and was subjected to euthanasia. Post mortem examination revealed multiple bullous emphysema with haemorrhage. This disorder should be considered in the differential diagnosis of foals having air‐fluid filled cavities on thoracic radiographs.     

IMAGING DIAGNOSIS—AORTIC ANEURYSM AND URETERAL OBSTRUCTION SECONDARY TO UMBILICAL ARTERY ABSCESSATION IN A 5‐WEEK‐OLD FOAL

A 5‐week‐old foal was evaluated for fever and hematuria of 3 days duration. Cystoscopy localized the blood to be originating from the left ureter. Abdominal ultrasonography revealed left hydronephrosis, hydroureter, and omphaloarteritis of the left umbilical artery with abscess formation that communicated with an arterial structure. Computed tomography (CT) revealed a large aortic aneurysm within the center of the abscess. An exploratory celiotomy was performed and the infection was nonresectable. The prognosis for life was grave; therefore the colt was euthanized. Necropsy findings confirmed the antemortem diagnosis. Ultrasound and CT imaging in this case provided an accurate antemortem diagnosis.     

Traumatic sacral fracture following dystocia in a Thoroughbred foal

A Thoroughbred colt with a history of dystocia was referred for further management of suspected hypoxia. The foal showed signs of neonatal maladjustment syndrome and hindlimb paralysis. Radiography revealed the presence of a severe lumbosacral injury. The foal was subjected to euthanasia due to a hopeless prognosis. Computed tomography was performed post‐mortem and revealed a type I Salter Harris fracture of the cranial physis of the first sacral vertebra.     

Possibilities for computer tomography of the equine head based on two cases with a fracture of the base of the skull]

For the past 2 years computed tomography is used at the Veterinary School, University of Zürich. This new imaging modality enables the detection of abnormalities occurring in small and large animals which were previously not visible with imaging techniques. Subjects of this study were a foal and a small pony, both with suspected head trauma. Routine radiography could not explain any of the neurological deficiencies. In the first case a basilar skull fracture along with a focal brain hemorrhage was detected, in the second case multiple basilar skull fractures were seen. The computed tomographic examination after intravenous injection of an iodine-containing contrast medium also revealed epidural hemorrhage. These two cases demonstrate the diagnostic use of computed tomography as an extremely valuable asset when diagnosing head trauma in horses.     

An unusual cause of colic in a neonatal foal

A case of a neonatal foal with acute colic and respiratory distress is described. The foal presented with signs of acute colic and was treated medically. The foal did not respond to treatment and 2 h after admission the foal began to demonstrate signs of respiratory distress. Thoracic and abdominal radiographs were obtained and a diagnosis of a diaphragmatic hernia was made. Surgical repair of the hernia was recommended but the owner declined and the foal was subjected to euthanasia. Post mortem findings confirmed the diagnosis and revealed that the defect was of congenital origin. Congenital diaphragmatic hernia is an unusual cause of colic in a neonatal foal.     

Intra‐abdominal cystic lymphangiomatosis in a Thoroughbred foal

Cystic lymphangiomas are rare malformations of the lymphatics that result in the formation of a cystic mass. Where multiple cysts are seen, the condition is termed cystic lymphangiomatosis. This case describes the diagnosis and unique management of cystic lymphangiomatosis in a 10‐day‐old Thoroughbred foal. Ultrasonography, histopathology and laparoscopy were essential for diagnosis and appreciation of the extent of disease. Ultimately, the cystic lymphangiomatosis was so extensive in this foal that complete surgical excision was considered impossible and the presence of adhesions within the abdomen indicated a very poor long‐term prognosis; the owners elected for euthanasia at age 14 weeks. Although rare, lymphangioma and lymphangiomatosis should be considered as a differential diagnosis for an intra‐abdominal mass in a young horse.     

Evaluation of a thoracic focused assessment with sonography for trauma (TFAST) protocol to detect pneumothorax and concurrent thoracic injury in 145 traumatized dogs

Objective: To estimate the relative accuracy of a thoracic focused assessment with sonography for trauma (TFAST) protocol for rapid diagnosis of pneumothorax (PTX) and other thoracic injury in traumatized dogs. Design: Prospective case series. Setting: Private veterinary emergency center. Animals: One hundred and forty‐five client‐owned dogs evaluated within 24‐hours of injury. Interventions: Thoracic focused assessment with sonography for trauma protocol. Measurements and Main Results: Traumatized dogs were evaluated with a conventional ultrasound (US) machine using a standardized 4‐point thoracic FAST protocol before thoracic radiography (CXR) and thoracocentesis. PTX was diagnosed by the absence of the ‘glide sign,’ defined as the lack of the normal dynamic interface between lung margins gliding along the thoracic wall during respiration. Concurrent thoracic trauma was diagnosed by the presence of pleural or pericardial fluid or the presence of a ‘step sign,’ defined as an abnormal glide sign. Accuracy of TFAST was calculated relative to CXR findings. Results: Overall sensitivity (Se), specificity (Sp), and accuracy of TFAST relative to CXR were 78.1% (95% CI; 61.5, 89.9), 93.4% (95% CI; 87.4, 97.1), and 90.0%, respectively. Se and Sp were higher in dogs with penetrating trauma (93.3%, 96.0%) and for the evaluator with the most clinical experience (95.2%, 96.0%); only Se between the most experienced compared with others was statistically significant (P<0.05). TFAST documented other concurrent thoracic injury. Median time for TFAST was 3 minutes. Conclusions and Clinical Relevance: TFAST has the potential to rapidly diagnose PTX and other thoracic injury and guide therapy, including potentially life‐saving interventions, in traumatized dogs.     

Presentation,stabilisation and contrast-enhanced computed tomographic (CT) diagnosis of a left gastrocaval portosystemic shunt in a pony foal

A 2-week-old pony foal was presented for recurrence of neurological dysfunction, obtunded-comatose mentation and collapse. Signalment, history, haematological and clinical chemical measurements and response to treatment prompted a presumptive diagnosis of hepatic encephalopathy secondary to a portosystemic shunt. This case differs from previous reported cases of  congenital portosystemic shunts in horses due to the early onset of clinical signs, which usually occur at 2–6 months of age. In addition, in comparison with previously reported cases, this foal stabilised rapidly with minimal intervention. Contrast-enhanced computed tomography (CT) confirmed a left gastrocaval extrahepatic portosystemic shunt. Surgical intervention was not attempted due to financial constraints, so the foal was subjected to euthanasia, and on post-mortem examination, the anomalous vascular connection could clearly be identified.     

Brain Abscess in a 4-Month-Old Filly: A Case Report

Although recognized as a possible complication to sepsis, there are few published reports on brain abscesses in foals. This case report describes a 4-month-old Icelandic filly that, as a neonate, had a history of pyrexia and lameness, which resolved with antibiotic treatment. Approximately 3 months later, the foal developed neurological signs which were initially attributed to trauma; she was referred for further investigation. The clinical signs were consistent with a lesion of the right forebrain. Computed tomography examination revealed a mass, approximately 6 cm in diameter, located in the right cerebral hemisphere craniolateral to the right lateral ventricle. Because of the poor prognosis, the foal was killed, and a postmortem was performed. The findings confirmed the presence of an abscess of the right cerebral hemisphere, leading to severe atrophy of the cortex and dilation of both lateral ventricles. The left hemisphere was moderate-to-severe atrophic and had displaced to the left. Streptococcus equi subspecies zooepidemicus was isolated in pure culture from the abscess. The clinical features of the foal were compared with the pathological findings.     

Use of multi‐detector computed tomographic angiography in the diagnosis of a parapharyngeal aneurysm in a 6‐week‐old foal

Multidetector‐row computed tomographic contrast angiography (MDCTA) is routinely employed to investigate vascular masses in human patients but, to date, the use of this technique to investigate an aneurysmal mass has not been reported in an equine case. The potential of MDCTA to investigate a right‐sided parapharyngeal mass in a 6‐week‐old Thoroughbred foal was therefore investigated. A 4‐slice helical computed tomography scanner was used on a superficial, firm, ovoid mass yielding arterial blood on fine needle aspiration. MDCTA enabled identification of the vessels involved thus assisting in forming a diagnosis based on the morphology of the lesion and aided surgical planning. Histology confirmed the presence of mural thrombus and calcification within the smooth muscle wall consistent with a true aneurysm. MDCTA provided additional information to conventional imaging in this case of vascular masses of the head and neck. The technique therefore has the potential to improve diagnosis and assist in the management of such lesions.     

IMAGING DIAGNOSIS — USE OF MULTIPHASE COMPUTED TOMOGRAPHIC UROGRAPHY IN THE DIAGNOSIS OF URETERAL TEAR IN A 6‐DAY‐OLD FOAL

A 6‐day‐old foal was evaluated for depression and inappetence. After initial stabilization, the filly developed a hypochloremic metabolic alkalosis and persistent hypercreatinemia. Abdominal ultrasound revealed fluid accumulation around the left kidney and a well‐defined rounded fluid filled structure dorsal to the urinary bladder. Computed tomography revealed a partial tear of the left ureter with distension of the retroperitoneal membrane. Exploratory celiotomy was performed to allow left kidney nephrectomy. At 6 months follow‐up, the filly was growing normally without complications. Ultrasound and CT imaging in this case provided an accurate diagnosis and a presurgical aid to select the appropriate therapeutic approach.     

Septic arthritis of the first and second cervical vertebral articulations with vertebral osteomyelitis in a foal caused by Salmonella

A case of infectious arthritis of a cervical vertebral articulation and vertebral osteomyelitis in a foal caused by Salmonella is described. Ultrasound images of the cervical facet joints were suggestive of septic arthritis and ultrasound facilitated needle placement for arthrocentesis and joint lavage. Due to the uncommon location of the infection, diagnosis of septic arthritis was not immediate and, despite aggressive intra‐articular lavage and instillation of appropriate intra‐articular antibiotics after hospitalisation, we were unable to resolve the infection in this foal. Radiographs did not show evidence of osseous involvement until later in the course of the infection. Septic arthritis should be suspected in cases with similar clinical and laboratory findings and radiographic changes may not be present early in the course of infection. Ultrasound imaging provided the most useful diagnostic information regarding infection of the cervical joints, facilitating both diagnosis and treatment.     

Electroretinographic changes after intravenous lipid emulsion therapy in a dog and a foal with ivermectin toxicosis

This case report describes ivermectin‐induced blindness in a dog and a foal with normal ophthalmic fundic examinations and attenuated electroretinography (ERG). Subsequent recovery in ERG was noted following intravenous lipid emulsion (ILE) therapy. A dog and a foal were evaluated for ivermectin‐induced blindness. Clinical signs included dull mentation, absent pupillary light reflexes (PLRs), and absent menace on presentation. The animals had normal fundoscopic examinations; however, in both cases ERG was consistent with neurosensory retinal dysfunction. Following ILE therapy for ivermectin toxicosis, return of menace, PLRs, and normal mentation were noted, as was improvement in ERG and serum ivermectin levels. These are the first documented cases of ivermectin‐induced blindness in a dog and a foal with normal fundic examinations and attenuated ERG. ERG improved in both animals after ILE therapy. ERG may assist in the diagnosis of ivermectin toxicosis in dogs and horses. ILE therapy may hasten recovery in treatment of ivermectin‐induced blindness.     

Neonatal respiratory distress and sepsis in the premature foal: Challenges with diagnosis and management

The presentation of a premature, neonatal foal affected with respiratory distress and seizures represents a difficult diagnostic and therapeutic challenge often best addressed by the provision of appropriate emergency care followed by prompt referral to a well‐equipped critical care facility. Veterinary management of the premature foal described in the accompanying report was complicated by the development of sepsis and pulmonary failure. The development of pulmonary emphysematous bullae was identified during the course of the foal's treatment and probably contributed to its clinical deterioration. Diagnostic imaging modalities that may be used for the diagnosis of respiratory distress in neonatal foals include thoracic radiography, ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). Both CT and MRI require general anaesthesia. The likelihood of a successful outcome for the foal in this report might have been improved by the provision of urgent veterinary care and referral to the critical care facility earlier in the course of its management. Important early indicators of the need for urgent veterinary care in this case included the foal's prematurity, inability to stand, and the need to provide manual support to facilitate nursing from the mare's udder. Foals affected in this manner should warrant treatment with broad‐spectrum antimicrobials, circulating volume maintenance, immunoglobulin support, and the use of a nasogastric tube to facilitate nutritional support.     

The use of CT and CT arthrography in diagnosing equine stifle injury in a Rheinlander gelding

A 5‐year‐old Rheinlander gelding was evaluated for left hindlimb stifle lameness. The lameness was localised to the stifle, but source of the lameness was not specifically diagnosed from the physical, radiographic and ultrasonographic examinations. Computed tomography (CT) and CT arthrography were therefore used for further investigation since these imaging techniques image bony structures, cartilage and soft tissues. This examination showed multiple lesions in the stifle: an osteochondrosis dissecans like lesion of the medial femoral condyle, bony fragments, cartilage trauma and caudal cruciate ligament injury. The prognosis for continuing use as a sports horse was regarded as unfavourable. Therefore, the horse was subjected to euthanasia. All CT findings were confirmed by gross pathology. The CT and CT arthrography examination in this case provided a diagnosis not achieved with other conventional imaging techniques.     

Diffuse osteomyelitis of the fourth metacarpal bone in a horse caused by Clostridium perfringens

Osteomyelitis in adult horses, often associated with trauma or iatrogenic infection following surgery, usually presents as a focal area of infected bone. Diffuse osteomyelitis, affecting both the cortex and medulla, along the full length of a bone is encountered less frequently and treatment of such infections is not well reported in horses. The 2-year-old Warmblood mare in this case was diagnosed with diffuse osteomyelitis affecting the 4th metacarpal bone with concurrent unicortical fracture of the third metacarpal bone following traumatic injury. Computed tomography (CT) aided diagnosis in this case, providing critical additional detail to that obtained with radiography and ultrasound. This case highlights the value of CT in the diagnosis of diffuse osteomyelitis. This is the first reported case of diffuse osteomyelitis caused by Clostridium perfringens in horses. Successful treatment in this case consisted of surgical debridement of the associated abscess, followed by systemic and locoregional antimicrobial therapies.