COMPARISON OF RADIOGRAPHIC AND SCINTIGRAPHIC FINDINGS OF THE SPINOUS PROCESSES IN THE EQUINE THORACOLUMBAR REGION

Back pain is common in horses, but there has been no large‐scale in‐depth study describing radiographic changes of the spinous processes, the relationship between radiographic and scintigraphic findings, and the effect of size, age, breed, or discipline. The objectives were to investigate the frequency of occurrence in horses with perceived back pain of: (1) radiographic alteration of the spinous process structure; (2) increased radiopharmaceutical uptake (IRU) in the spinous processes; and (3) to compare radiographic and scintigraphic findings; and to determine if there was breed, gender, age, bodyweight, height, or work discipline predisposition for close, impinging, or overriding spinous processes. Radiographic and scintigraphic images of the thoracolumbar spine of 604 horses were graded. A radiographic grade for each spinous process (T8–L6) was assigned (0–7). The maximum radiographic grade for each horse was defined as the highest grade assigned to any spinous process; the total radiographic grade was the sum of all grades for each horse. A scintigraphic grade for each spinous process was determined (0–3). The maximum scintigraphic grade for each horse was defined as the highest grade assigned to any spinous process; the total scintigraphic grade was the sum of all grades for each horse. Associations between radiology and scintigraphy and age, gender, breed, height, weight, and discipline were analyzed statistically. The severity of radiographic lesions of the spinous processes was associated with the severity of scintigraphic abnormalities. The caudal thoracic spine (T14–T17) was most frequently affected. There was a significant breed and age effect, with Thoroughbreds and older horses having higher total and maximum radiographic grades. The severity of the lesions of the spinous processes was significantly associated with the presence of osteoarthritis of the articular process joints. It was concluded that there is a wide range of radiographic abnormalities of the spinous processes seen in horses with or without back pain. There is an association between radiographic and scintigraphic grades of the spinous processes.     

Relationship between scintigraphic and radiographic evaluations of spinous processes in the thoracolumbar spine in riding horses without clinical signs of back problems

REASONS FOR PERFORMING STUDY: Radiography and scintigraphy are used to aid diagnosis of the cause of back pain, but a large variation in appearance and radiopharmaceutical uptake in fully functioning horses make diagnosis difficult. OBJECTIVES: To describe the range of and compare scintigraphic and radiographic findings in the spinous processes of horses without clinical signs of back problems. METHODS: Thirty-three apparently normal riding horses underwent scintigraphic and radiographic examinations of the spinous processes in the thoracolumbar spine. Scintigraphic images were evaluated in a continuous blue, green and red colour scale, and the level of radiopharmaceutical uptake in the spinous processes from T10-L2 was graded into none, mild, moderate or severe increased radiopharmaceutical uptake. Structural changes along the borders of the spinous processes and the width of the interspinous spaces from T10-L2 were recorded. RESULTS: Only 7 horses had no scintigraphic or radiographic findings. Nine horses had no increased radiopharmaceutical uptake, 17 had no sclerosis, 21 had no radiolucencies and 11 had normal spacing of the spinous processes (>4 mm wide). The majority of findings in 26 horses were located from T13-18 and were mild. CONCLUSIONS: The findings of a wide spectrum of scintigraphic and radiographic changes leads to the conclusion that changes within this range found in affected horses cannot be interpreted as clinically significant. POTENTIAL RELEVANCE: To determine whether scintigraphy and/or radiography can be used to separate horses with back pain from horses without clinical signs, the results from this study should be compared to the scintigraphic and radiographic findings in horses with clinical signs.     

Radiographic Features of the Normal Equine Thoracolumbar Spine

The normal radiographic anatomy of the equine thoracolumbar (TL) spine is described from birth to maturity. Closure of the vertebral epiphyses was found to take place from 30 to 38 months of age. In a series of 110 normal horses, there were few incidental radiologic abnormalities seen apart from changes associated with crowding and overriding of the dorsal spinous processes. Sixty-six percent of horses were free from any detectable radiologic lesion, and an additional 12 percent showed only impingement of the dorsal tips of one or more summits. The remainder (22 percent) exhibited some evidence of overriding of the dorsal spinous processes, but in only 3 percent were the changes pronounced. This reduction or obliteration of the normal interspinous spaces occurred chiefly in the midback from T13 to T18 and was associated with pressure points between adjacent spines with local periosteal reaction and focal areas of radiolucency. The tips of the processes sometimes overlapped one another and became misshapen, presumably as a result of continued pressure from the adjacent impinging spines.     

Dorsal spinous process impingement syndrome ('kissing spine') in a cat: imaging appearance and surgical management

Spinal pain is an important clinical presentation in feline patients, but the underlying causes can often be difficult to elucidate. Dorsal spinous process impingement syndrome ('kissing spine' or in human patients 'Baastrup syndrome') is a significant cause of spinal pain in equine and human patients and radiographically is characterised by a close approximation of adjacent spinous processes with reactive bone sclerosis affecting these spinous processes. In this report we describe the first reported case of dorsal spinous process impingement syndrome in a cat causing spinal pain, and successful surgical management of the syndrome. The affected cat presented at 5 years of age for evaluation of a 7-month history of progressive thoracolumbar pain. Radiographs revealed close approximation of the dorsal spinous processes of the seventh, eighth and ninth thoracic vertebrae (T7, T8 and T9), with associated reactive bone sclerosis. Surgical resection of the T8 dorsal spinous process resulted in complete resolution of the clinical signs with no evidence of recurrence 9 months after surgery.     

Progression of Femoropatellar Osteochondrosis in Nine Young Horses Clinical, Radiographic and Arthroscopic Findings

The clinical and radiographic progression, and arthroscopic findings for nine young horses (<1 year of age) with femoropatellar osteochondrosis (OCD) are presented. Horses had a 2 to 12 week history of bilateral (8 horses) or unilateral (1 horse) hindlimb lameness. The most consistent clinical signs included femoropatellar joint distention and bilateral hindlimb lameness. At the onset of clinical signs, radiographic lesions were not present (4 horses) or subtle (5 horses), but were easily identified on radiographs taken 4 to 24 weeks later. Arthroscopic surgery was delayed until radiographic changes became obvious. Surgical findings in 20 femoropatellar joints were most commonly osteochondral "flaps" located on the proximal lateral trochlear ridge of the femur and were larger than had been indicated by the radiographs. Eight horses were being used for their intended purpose, which was racing (3 horses were racing and 3 were in race training), dressage (1 horse) or pleasure riding (1 horse). One horse required a second surgery when similar lesions developed in the opposite stifle, and was euthanatized 2 months later because of persistent lameness. Once clinical signs are observed, osteochondrosis lesions of the distal femur can progress in foals younger than 9 months of age and the full extent of the radiographic lesion may take several weeks to develop.     

Healing of multiple fractured thoracic dorsal spinous processes in a Quarter horse

A Quarter horse gelding sustained fracture and displacement of spinous processes T2-T10. Radiographic evidence of healing was seen 3 mo following injury, and at 2 years post-injury all spinous processes had healed and undergone partial re-alignment. This re-alignment has not been reported before.     

Distances between thoracic spinous processes in Warmblood foals: A radiographic study

Reason for performing study: The aetiological factors behind impinged or overriding of dorsal spinous processes (‘kissing spine syndrome’, KSS) are not clearly understood. Back conformation, breed, age, training and gender may play important roles in this condition. Radiographic changes vary and abnormalities are seen in many clinically normal horses, but the conclusion of previous studies in mature horses is that interspinous spaces <4 mm are considered too narrow and potentially indicative of KSS. Objectives: To evaluate whether narrowing of the interspinous space was present in a population of normal Warmblood foals. Materials and methods: The mean interspinous space width in the area of T10–L1 was measured on radiographs from 25 Warmblood foals aged 9–88 days. Results: Mean ± s.d. interspinous space width was found to be between 5.9 ± 1.2 and 8.9 ± 2.6 mm with the narrowest space in the area T16–T17 and the widest space in T10–T12. No interspinous spaces were <4 mm wide. Gender and location of the interspinous space significantly affected the width of the distance between the spinous processes. Conclusions and potential relevance: In this study none of the interspinous spaces were <4 mm and therefore none of the foals showed signs of impinged or overriding of dorsal spinous processes known as KSS based on the current definitions. Consequently, in this population, there did not appear to be a congenital narrowing of the interspinous space. However, long‐term follow‐up studies, including detailed information on imposed factors such as training, are needed in order to further elucidate a possible congenital component in the aetiology of KSS.     

Fistulous withers in horses: 14 cases (1978-1987)

Over an 8-year period, 14 horses were admitted to the New York State College of Veterinary Medicine for evaluation of fistulous withers. Of the 14 horses, 11 were treated surgically and 3 were not treated. Surgical techniques involved radical excision of the affected soft tissue and spinous processes of affected vertebrae. Recurrence rate was 30%, and these horses required additional surgery to resolve the problem.     

RADIOGRAPHIC TECHNIQUE AND ANATOMY OF THE EQUINE SACROILIAC REGION

Radiography is part of evaluating horses with poor performance and pelvic limb lameness; however, the radiographic appearance of the sacroiliac region is poorly described. The goal of the present study was to describe the use of a simple technique to obtain radiographs of the sacroiliac region in the anesthetized horse and to describe the radiographic appearance of this region. Seventy-nine horses underwent radiography of the pelvis under general anesthesia in dorsal recumbency. During a 5s exposure time the horse was actively ventilated to blur the abdominal viscera, which allowed assessment of individual bone structures in 77 horses. A large variation in the shape of the sacral wings, their articulation with the transverse processes of L6, and the relation of the sacrum to the ilium were observed. Females had significantly narrower width of the sacral wings. Broad sacral wings and bony proliferations at the caudal aspect were commonly observed features and their size was highly correlated with gender. In males, caudal osteophytes were significantly larger than in females. Five horses had transitional or hemitransitional vertebrae. Radiography with the ventilation-induced blurring technique is a simple approach that results in diagnostic quality radiographs and delineation of the highly variable bone structures of the sacroiliac region.     

An unusual location of foreign body in the horse

A seven year old Arabian gelding was presented because of a draining tract cranial to the scapula that developed following puncture with a wooden rail four months previously and drained continuously despite antibiotic treatment.

The full extent of the tract could not be determined with the horse standing but a polyethylene catheter was passed 25 cm down the tract and passed medial to the scapula. With the horse under a general anaesthetic, further probing revealed the tract was much longer. The direction, length and contents of the tract were determined by fistulograph. The tract continued medial to the scapula and terminated with two radiolucent filling defects adjacent the spinous processes of the 5th-11th thoracic vertebrae. The filling defects were located more accurately in a cranial-caudal direction by the use of radiopaque markers, and in a medial-lateral direction by deep needle probing during surgery. Following surgical removal of the foreign bodies the tract healed and the horse returned to his original use. Foreign bodies and the use of fistulography are discussed.

     

A correlative study of the clinical and radiographic signs of periodontal disease in dogs

Twenty-four dogs admitted for routine teeth cleaning were selected arbitrarily to undergo a periodontal examination and a dental radiographic examination before the dental procedure. Data pertaining to the physical and radiographic manifestations of periodontal disease of 783 teeth were collected. All dogs had lesions consistent with periodontal disease, ranging from mild gingivitis and minimal plaque accumulation to severely inflamed gingiva, exuberant calculus formation, and root exposure. Of the 783 teeth examined, 153 (20%) had a pocket depth greater than or equal to 4 mm and less than or equal to 9 mm. Data regarding these teeth were subjected to statistical analysis. The clinical signs of plaque, calculus, mobility, pocket depth, and furcation were positively associated with radiographic signs of periodonta disease. The association between grossly evident gingivitis and radiographic signs of periodontal disease was not significant. Conditional probability analysis was applied to determine confidence intervals for the probability of a radiographic sign of periodontal disease occurring given that a clinical sign of periodontal disease occurs.     

Canine diffuse idiopathic skeletal hyperostosis

The radiographic and necropsy findings in a case of canine diffuse idiopathic skeletal hyperostosis are reported. Radiographically, the disease was characterized by progressive development of para-articular mineral densities along joint surfaces of the appendicular skeleton; progressive osseous fusion of the ilium, pubis, femur, and ischium; and progressive flowing ossification of the dorsal spinous processes of cervical and thoracic vertebrae. The para-articular lesions were considered to develop as a consequence of fibrocartilaginous proliferation followed by endochondral ossification. Progression of the ossification process led to para-articular joint fusion and almost complete ossification of the metaplastic cartilage. A distinguishing feature was the sparing of intra-articular structures.     

Implications of the neuroanatomy of the equine thoracolumbar vertebral column with regional anaesthesia and complications following desmotomy of the interspinous ligament

Impinging/overriding dorsal spinous processes (DSPs) of the thoracolumbar vertebrae are a common cause of poor performance in horses. In the last five decades, numerous surgical treatments have been reported on, from transverse transection of the affected DSPs, and endoscopic resection of the affected DSPs, to transection of the interspinous ligament. Until recently, cosmetic outcomes have been reported as good to excellent in studies. However, a previously unreported complication of neurogenic atrophy of the contralateral epaxial muscle following desmotomy of the interspinous ligament has been recently reported. The authors hypothesised that this was because of a more lateral approach than previously described, resulting in the scissors being too far across midline and transecting a nerve in the region. Considering this finding, we have reviewed the literature on the neuroanatomy of the thoracolumbar region in the horse. Literature on the neuroanatomy of the horse is lacking when compared with that of humans and companion animals, with most of the work extrapolated from companion animals. Based on the current literature, we hypothesise that transection of an intermediate branch of the dorsal spinal nerve supplying the m. longissimus is potentially the cause of the post-operative neurogenic atrophy. The lack of detailed knowledge of the neural anatomy of the equine back has resulted in the role of local anaesthesia in localising pain in the equine back being poorly understood. The wide variation in techniques used for localising back pain may explain why some horses suffering from poor performance or an abnormal gait because of back pain improve to local anaesthesia of the back while others do not. This review article highlights a lack of anatomical knowledge regarding the equine thoracolumbar region in the literature despite diagnostic local anaesthesia, medication, and surgery in this area being relatively common.     

Diagnosis of equine stifle joint disorders: three cases

The clinical, radiographic, arthrographic, arthroscopic, and pathological findings of three horses with femorotibial joint injuries are presented. Overall diagnostic accuracy is improved when clinical signs, arthrography, and arthroscopy are combined. Treatment of these injuries remains limited. One horse was euthanized, and two were treated by stall rest after diagnosis. Of the two surviving horses, one became a successful breeding animal, and the other was unable to perform as a pleasure horse.     

Breed and species comparison of amino acid transport variation in equine erythrocytes

The amino acid permeability of red blood cells from Equus caballus (thoroughbred, Arab, shire and pony), E przewalskii (Przewalski's horse), E asinus (donkey and mule) and E burchelli (common or plains zebra) was measured. Individual animals exhibited stable but widely differing rates of L-[U-14C]alanine uptake in the range 5 to 1554 mumol (litre cells)-1 h-1 (0.2 mM extracellular L-alanine, 37 degrees C). Of the thoroughbreds tested, 30 per cent had red blood cells which were essentially impermeable to L-alanine (5 to 10 mumol (litre cells)-1 h-1, giving transport rates similar to those found previously in amino acid transport-deficient sheep erythrocytes. In contrast, only 3 per cent of the ponies tested had red blood cells impermeable to L-alanine. No cases of erythrocyte amino acid transport deficiency were found in the other horse breeds and species tested.     

Eikenella corrodens osteomyelitis of the axis in a foal

Eikenella corrodens, a previously unrecognized pathogen in the horse, was isolated from the spinous process of the axis of a colt with signs of severe neck pain. Dorsal laminectomy (excising the infected spinous process and lamina) was performed and the colt was treated with antibiotics for 6 weeks. Recovery was uncomplicated.     

Problems associated with the interpretation of the results of regional and intra-articular anaesthesia in the horse

The difficulties associated with the interpretation of the results of regional and intra-articular anaesthesia are discussed with reference to eight lame horses. The clinical and radiographic features of each horse are described, together with the results of anaesthesia. One horse had clinical and radiographic signs consistent with navicular disease but it was not possible to relieve the lameness. Two horses had fractures of bones within the foot but lameness was not improved by palmar (abaxial sesamoid) nerve blocks. One horse had more than one cause of lameness. Four horses had joint pathology but none responded to intra-articular anaesthesia.     

Subtotal ostectomy of dorsal spinous processes performed in nine standing horses

OBJECTIVE: To describe and evaluate subtotal ostectomy of dorsal spinous processes (DSP) performed in standing horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Nine adult horses. METHODS: The diseased portions of the DSP were removed with the horses standing and sedated after infiltrating a local anesthetic agent around the affected DSP. Medical records of affected horses were reviewed to determine history, findings of physical and radiographic examination, surgical technique, postoperative complications, and outcome. RESULTS: Five horses had subtotal ostectomy of DSP because of osteomyelitis, and 4 because of impingement and/or fracture of DSP. Affected portions of DSP were removed safely and effectively, with no apparent discomfort to the horses; hemorrhage was minimal. CONCLUSIONS: Subtotal ostectomy of DSP can be performed safely in standing, conscious horses and the risks associated with general anesthesia are eliminated. Hemorrhage is minimal compared to that which occurs when the procedure is performed with horses anesthetized and in lateral recumbency. CLINICAL RELEVANCE: Access and visibility are better when subtotal ostectomy of the DSP is performed with the horse standing rather than anesthetized and in lateral recumbency. Performing subtotal ostectomy of diseased DSP with the horse standing avoids the expense and risks of general anesthesia.     

RADIOGRAPHIC FINDINGS DURING RECOVERY FROM DISCOSPONDYLITIS

The diagnosis of discospondylitis is based on radiographic changes in the vertebrae. The limitations of this method are the time gap between the onset of clinical signs and the first appearance of the radiographic findings, as well as the disassociation between the clinical and radiographic signs during recovery. It is known that the radiographic changes appear only two to four weeks after the onset of clinical signs, but the characteristics of radiographic changes during recovery has yet to be documented, thus making follow-up radiographs difficult to interpret. A prospective and retrospective study was designed to document typical radiographic changes during recovery from discospondylitis. We reviewed 12 dogs that had complete and uneventful recovery with antibiotic therapy alone. Periodic follow-up radiographs and clinical examinations were conducted up to five months after the onset of clinical signs to correlate between the clinical status and radiographic changes during recovery. Although the clinical signs improved within the first 10 days of antibiotic therapy, the radiographic deterioration continued before regression and signs of radiographic recovery were noticed. This radiographic deterioration, despite successful antibiotic therapy, appeared shorter in young dogs (less than one year old) and lasted three to nine weeks in older dogs.