Multiple skeletal metastases from a penile squamous cell carcinoma in a horse

A 21‐year‐old gelding with ventral abdominal and preputial oedema was evaluated for right hindlimb lameness. Partial phallectomy had been performed 3 years prior for treatment of squamous cell carcinoma. Regional analgesia did not localise the source of lameness and nuclear scintigraphy was recommended. The results of the scan revealed severe increased radiopharmaceutical uptake in the proximal femur. Radiographic and ultrasound examinations were inconclusive. The horse was discharged with recommendations of stall confinement and a 2 week course of nonsteroidal anti‐inflammatory drugs. Four weeks later the horse presented for an inability to elevate his neck and persistent hindlimb lameness. The owner elected humane euthanasia. Post mortem examination revealed metastatic squamous cell carcinoma in the proximal femur and fifth cervical vertebrae consistent with metastasis from the penile squamous cell carcinoma. To the authors’ knowledge, multiple site bone metastasis of squamous cell carcinoma has not been reported previously in the horse.     

Osteosarcoma of the middle phalanx in a horse

An 11‐year‐old Thoroughbred gelding was presented for lameness investigation following acute onset hindlimb lameness, which developed during a period of paddock turnout. Clinical examination revealed a swelling over the dorsolateral aspect of the pastern that was painful on digital palpation. Radiography of this area was consistent with an aggressive bone lesion involving both joint surfaces of the middle phalanx with pathological fracture and distal collapse of this bone. On this basis, the horse was subjected to euthanasia. Post mortem histopathological examination revealed presence of an osteosarcoma without involvement of the articular cartilage. This bone tumour is extremely rare in horses and has not been reported in this anatomical location.     

Clinical significance of ossification of the cartilages of the front feet based on nuclear bone scintigraphy, radiography and lameness examinations in 21 Finnhorses

REASONS FOR PERFORMING STUDY: Research on the clinical significance of ossification of the cartilages of the foot has been limited, despite the common nature of the condition and conflicting reports in previous literature. HYPOTHESIS: Some radiographic features in the ossification of the cartilages, such as incomplete fusion lines between separate centres of ossification and the ossified base, are of clinical significance. METHODS: The relationships between radiopharmaceutical uptake in bone phase nuclear scintigraphy at the heels (palmar processes of the distal phalanx, including ossification of the cartilages of the foot), radiographic extent and type of ossification of the cartilages and clinical lameness were evaluated retrospectively in 21 Finnhorses (age > or = 4 years) in a total of 36 front feet. RESULTS: No significant relationship between height of the ossifications and radiopharmaceutical uptake at the ipsilateral heels existed. Clearly separate centres of ossification were not associated with increased uptake. Moderately increased uptake was suspected to be associated with ossification of the adjacent cartilage in only one foot. Intense uptake was present unilaterally in 4 horses, at one medial and 3 lateral heels. In 2 of these horses, a unilateral palmar digital nerve block relieved the mild lameness; 2 horses had no obvious lameness but had a history of being stiff or having locomotion problems during high speed trot. At 2 of the lateral heels, an incomplete fusion line was present between a large separate centre of ossification and the base, and the third horse had a high sidebone with bony protrusions, suggestive of chronic entheseopathy in a narrow foot. At the medial heel, an oblique radiograph revealed a faint radiolucent line at the base of the ossification. In all cartilages with intense radiopharmaceutical uptake at the heel and/or lameness, the ossified part of the cartilage was wider and more irregular compared to other ossifications of the front feet of the individual. CONCLUSIONS: Increased radiopharmaceutical uptake, associated with a different radiographic appearance from that of other ossifications of the front feet, was a conclusive sign of clinical significance. Obscure locomotion problems were more commonly associated with ossification of the cartilages than true lameness. POTENTIAL RELEVANCE: This information is useful in lameness and prepurchase examinations and is likely also to be applicable to other coldblooded breeds used for athletic purposes.     

Use of the Cobra Head Bone Plate for Distal Long Bone Fractures in Large Animals A Report of Four Cases

Four long bone fractures with a short distal fragment were repaired with a cobra head bone plate alone (2 cattle) or in combination with a straight, broad dynamic compression plate (2 horses). Three fractures were of the distal femur (1 horse, 2 cattle) and one was of the distal radius (1 horse). The long-term outcome of the three femoral fractures was soundness in one case and mild lameness in two. Although satisfactory bone healing progressed in the horse with the radial fracture, laminitis in the contralateral forelimb necessitated euthanasia at week 6.     

Clinical findings associated with chronic ischial fracture in a gelding

An 8-year-old show-jumper gelding was referred for examination as a result of a purchase dispute for reported back pain. Clinical examination identified back pain and atrophy of the left semimembranosus and semitendinosus muscles, but no lameness. Standing pelvic radiography demonstrated a chronic nonunion fracture of the left ischium, the clinical significance of which was uncertain. The apparent back pain was thought to be probably unrelated to the pelvic lesion. We conclude that chronic ischial fracture in the horse can lead to specific atrophy of the semimembranosus and semitendinosus muscles, which originate from this bone.     

Lameness Associated with Mineralization of the Central Tarsal Bone and a Small Osseous Cyst-Like Lesion in Two Sport Horses

The clinical features, response to local analgesia, and imaging findings of two mature sport horses with lameness associated with abnormal mineralization of the dorsal aspect of the central tarsal bone and a small osseous cyst-like lesion are described. Although the radiological findings and the lesions identified using magnetic resonance imaging were similar, the lameness characteristics and responses to perineural analgesia differed. One horse failed to respond to treatment and was retired. The second horse was humanely destroyed. Postmortem examination confirmed the presence of an osseous cyst-like lesion distal to the subchondral bone plate of the central tarsal bone and extensive dense cancellous bone extending one-half the dorsoplantar depth of the bone.     

The ossification of cartilages of the distal phalanx in the horse: An anatomical, experimental, radiographic and clinical study

This paper describes some anatomical findings relatedto ossification of the distal phalanx cartilages by anatomical and computerized tomographic sections. Radiographic findings of ossification were analyzed and correlated to age and breed. Ossification was found in 10% of warmblood horses and in 80% of draft horses and was much more severe in draft horses than in warmblood horses. The expansion of the hoof was measured in the laboratory in several feet of warmblood and draft horses and was found to be minimal with no differences whether ossification was present or not. Computerized tomography was performed on a foot of a slaughtered horse before and after up to 7000N loading in the laboratory in order to study the eventual changes of the cartilages and the hoof. These structures seemed quite unaffected by the load and expansion of the horny capsule was minimal. Minor expansion seems an inevitable structural behavior of the hoof and the classical hoof mechanism is questioned. The clinical significance of ossification in its relation to lameness was individually determined during clinical examination and by comparison of groups of horses with and without ossification with groups of horses with lameness from the foot and proximal to the foot. The severity of the ossification was related to the onset of lameness and no correlation was found. It is concluded that the clinical significance of ossification is almost nil. Ossification is not painful when developing and not thereafter. There is no correlation between navicular disease and ossification of the cartilages either. Orthopedic shoeing is of no significance at all. An unfavorable advice in purchase examinations in sporting horses due to cartilage ossification is not justified in the author's opinion.     

Use of magnetic resonance imaging for identifying subchondral bone damage in horses: 11 cases (1999-2003)

OBJECTIVE: To assess the use of magnetic resonance (MR) imaging for identifying subchondral bone damage in the distal limbs of horses. DESIGN: Retrospective study. ANIMALS: 11 horses. PROCEDURE: Medical records of horses with lameness and subsequent evidence of subchondral bone damage as determined by MR imaging were reviewed. Severity and duration of lameness, results of diagnostic local anesthesia and diagnostic testing, surgical and necropsy findings, and treatment were recorded. Outcome was determined by follow-up information obtained from the owner or referring veterinarian. RESULTS: Lameness was localized by physical examination and diagnostic local anesthesia. Lameness was localized to the metacarpophalangeal or metatarsophalangeal joint in 4 horses, distal interphalangeal joint in 5 horses, and tarsocrural joint in 2 horses. The duration of lameness ranged from 2 weeks to 20 months. Magnetic resonance imaging of the affected joints revealed abnormal fluid accumulation within the subchondral bone. None of the abnormalities observed by MR imaging were detected by radiography. Subchondral bone damage was diagnosed in all horses. Arthroscopy of the affected joint was performed in 4 horses. Communication with the articular surface of the affected bone was suspected on the basis of results of MR imaging in 4 horses and was confirmed by arthroscopy in 1 horse and by necropsy in 1 horse. CONCLUSIONS AND CLINICAL RELEVANCE: Magnetic resonance imaging was useful for providing a diagnosis when other imaging techniques did not definitively identify the cause of lameness. Subchondral bone damage was clearly identified by MR imaging and should be considered as a cause of lameness in horses in which radiographic findings are unremarkable.     

MRI and CT diagnosis of acute desmopathy of the lateral collateral sesmoidean (navicular) ligament and long-term outcome in a horse

Clinical, magnetic resonance imaging (MRI) and computed tomography (CT) findings of acute desmopathy of the lateral collateral sesmoidean (navicular) ligament (CSL) in a 13-year-old Hanoverian mare are presented. On admission to the clinic the horse showed a grade 5/6 left front-limb lameness at the walk, pain on coffin joint manipulation, and coffin joint effusion. Despite a positive palmar digital nerve block, radiographs and ultrasonography did not indicate reasons for the severe clinical signs. However, MRI revealed damage to the CSL and bone marrow oedema of the navicular bone (NB), whereas a focal bone defect of the NB at the CSL insertion zone was demonstrated best by CT. The horse was managed with complete box rest and a fibreglass cast for four weeks followed by a controlled exercise program. Follow-up examination revealed no lameness at the trot three months later and the patient had fully recovered within six months.     

Multifocal discrete osteolysis in a horse with silicate associated osteoporosis

Silicate associated osteoporosis (SAO) was diagnosed post-mortem in an adult horse with the shortest documented exposure to cytotoxic silicates of 2 years. The horse was evaluated for a 6-month history of progressive back tenderness and acute onset of lameness. The horse had a marked (4/5) (American Association of Equine Practitioners scale) left forelimb lameness, moderate (2/5) hindlimb ataxia and weakness, and cervical pain upon palpation. Physical examination did not reveal clinical skeletal deformities or respiratory compromise. Radiographs revealed widespread, discrete, sharply delineated, osteolytic lesions in the skull, vertebral column, ribs, scapulae and middle phalanx (P2) of the left forelimb and a diffuse bronchointerstitial lung pattern. The presumptive clinical diagnosis was widespread, metastatic osteolytic neoplasia. Due to the poor quality of life and grave prognosis, the horse was humanely euthanised. Post-mortem examination revealed pulmonary silicosis in the lungs and hilar lymph nodes and osteolytic lesions with numerous, large osteoclasts and disorganised bone remodelling both consistent with SAO. SAO should be included as a differential diagnosis for horses with widespread, multifocal, discrete osteolysis and history of exposure to endemic regions with possible cytotoxic silicate inhalation. Exposure time of 2 years is potentially sufficient to develop SAO.     

Consequences of capital femoral dyschondroplasia in young adult and skeletally mature broilers

Radiographs revealed defective endochondral ossification in proximal femora of 52 lame broilers. Cartilage retention either involved epiphyseal cartilage close to the articular surface or growth plate cartilage (dyschondroplasia). In at least seven birds proximal femoral lesions were the only abnormalities detected which could have caused lameness. In cases of moderate or severe cartilage retention, fracture lines traversed necrotic cartilage to undermine part or all of the femoral head. Evidence of reparative fibrosis was seen with augmentation of metaphyseal trabeculae by woven bone apposition. Foveal blood vessels aided repair by re-establishing a new ossification centre but in many cases attempts at repair were inadequate.     

Clinical evaluation of the effects of immobilization followed by remobilization and exercise on the metacarpophalangeal joint in horses

OBJECTIVES: To evaluate clinical effects of immobilization followed by remobilization and exercise on the metacarpophalangeal joint (MPJ) in horses. ANIMALS: 5 healthy horses. PROCEDURE: After lameness, radiographic, and force plate examinations to determine musculoskeletal health, 1 forelimb of each horse was immobilized in a fiberglass cast for 7 weeks, followed by cast removal and increasing amounts of exercise, beginning with hand-walking and ending with treadmill exercise. Lameness examination, arthrocentesis of both MPJ, single-emulsion radiographic examination, nuclear scintigraphic examination, ground-reaction force-plate analysis, and computed tomographic examination were done at various times during the study. RESULTS: All horses were lame in the immobilized MPJ after cast removal; lameness improved slightly with exercise. Force plate analysis revealed a significant difference in peak forces between immobilized and contralateral limbs 2 weeks after cast removal. Range of motion of the immobilized MPJ was significantly decreased, and joint circumference was significantly increased, compared with baseline values, during the exercise period. Osteopenia was subjectively detected in the immobilized limbs. Significant increase in the uptake of radionucleotide within bones of the immobilized MPJ after cast removal and at the end of the study were detected. Loss of mineral opacity, increased vascular channels in the subchondral bone, and thickening within the soft tissues of the immobilized MPJ were detected. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that 8 weeks of enforced exercise after 7 weeks of joint immobilization did not restore joint function or values for various joint measurements determined prior to immobilization.     

Fracture repair of the distal portion of the radius by use of a condylar screw implant in an adult horse.

An 8-year-old American Quarter Horse gelding was evaluated because of an open fracture involving the left radius. The horse had fallen during training and became immediately non-weight-bearing in the left forelimb. On initial evaluation, the horse was unable to bear weight on that limb; radiography revealed a long oblique fracture of the distal metaphysis of the radius with minimal displacement of the fracture fragments. Because of the configuration of the fracture, we recommended surgical intervention with internal fixation. A condylar screw implant and 4.5-mm broad dynamic compression plate were applied to the medial and dorsolateral aspects of the radius, respectively. The horse recovered in a sling and full-limb bandage. Six months after discharge, the horse was reevaluated because of a grade 4/5 lameness in the same limb. Palpation revealed signs of severe pain over the distomedial aspect of the radius. Radiography of the left radius revealed severe osteolysis beneath the distal aspect of the condylar screw implant. Surgical removal of the medial plate was performed. Sixteen months after the initial fracture repair, the horse had returned to light training without signs of lameness. Removal of the dorsal plate may be indicated if this horse is to return to aggressive training or becomes lame in the left forelimb.     

Placement of bone screws in a standing horse for treatment of a fracture of the greater tubercle of the humerus

A mature Thoroughbred gelding that was used as a high level jumper presented for evaluation of a nonweightbearing forelimb lameness following a fall. Radiographs revealed a complete, noncomminuted, minimally displaced sagittal fracture of the greater tubercle. Supporting limb laminitis was a major concern in the short term based on the severe lameness at presentation. Open reduction with internal fixation was chosen over stall rest in an attempt to more rapidly return the weightbearing function to the limb. The procedure was performed standing and 3 bone screws were placed standing in an attempt to avoid implant or catastrophic bone failure that can accompany recovery from general anaesthesia. The day following surgery the lameness was significantly improved as the horse was able to bear some weight on the heel. The gelding was discharged 5 days following surgery and was fully weightbearing at the walk. Six months following surgery the horse was free of lameness and resumed training. This report describes our experience and rationale in placing bone screws in a standing horse for treatment of a greater tubercle fracture.     

Standing biceps brachii tenectomy to treat chronic bicipital tendinopathy associated with bursal fibrosis and humeral adhesions in a Quarter Horse gelding

Chronic biceps brachii (BB) tendinopathy is a rare cause of lameness in horses that can be challenging to diagnose and treat successfully. This pathology is typically insidious in onset and unresponsive to conservative treatment. A 12-year-old Quarter Horse gelding presented for chronic severe lameness of the left forelimb that was localised to the left shoulder area. The horse was unresponsive to conservative management and surgical exploration revealed a grossly enlarged proximal BB tendon, a thickened fibrotic bicipital bursa and adhesions between the tendon, humerus and bursa. With standing sedation and local anaesthesia, the adhesions were debrided and 10 cm of the affected tendon was excised. Immediately post-operatively, the left forelimb lameness dramatically decreased. The horse recovered well and after rehabilitation returned to the previous level of athletic performance without evidence of lameness or gait abnormality. In this case, tenectomy of the chronic unresponsive BB tendinopathy, with associated bursal fibrosis and humeral adhesions, was successful and resulted in a return to previous athletic performance without complications. Standing excision of the BB tendon may be a viable treatment option for chronic BB tendinopathy and associated conditions when there is significant compromise to the integrity of the BB tendon.     

Use of a condylar screw plate for repair of a Salter-Harris type-III fracture of the femur in a 2-year-old horse

A 2-year-old sexually intact male Paint horse weighing 427 kg (940 lb) was admitted for examination and treatment of intermittent non-weight-bearing lameness of the right hind limb of 1 week's duration. Radiography revealed a displaced Salter-Harris type-III fracture of the right femoral condyle with the sagittal component of the fracture line located in the intercondylar space and the transverse component exiting on the medial aspect of the femur. The fracture was repaired with a condylar screw plate designed for repair of femoral condylar fractures in humans. The owner reported by telephone 9 months after surgery that the horse was sound. To our knowledge, use of this particular implant system for fixation of a Salter-Harris type-III fracture on the medial side of the femur in a horse has not been described. Results in this horse suggest that this implant can be successfully used for repair of femoral condylar fractures in selected adult horses.     

Vascular hamartoma as the cause of hind limb lameness in a horse

We report a 5-year-old gelding with a rare benign tumour of 2-month duration in the subcutis of the hind limb that presented with lameness. Physical examination revealed normal vital signs. Laboratory findings were within normal ranges. No bone abnormalities were detected on radiographic examination of the affected area. Bloody fluid was obtained by aspiration. Through an I-shape skin incision the tumour was excised en-block. Microscopic study showed a vascular hamartoma characterized by cavernous haemangiomatous tissue and proliferation of multiple vessels of variable diameter. This report highlights the importance of limb vascular hamartoma, as an infrequent lesion, in the differential diagnosis of lameness in the horse.     

Can distal border fragments of the navicular bone be a primary cause of lameness?

A horse with unilateral forelimb lameness and pain localised to the palmar aspect of the foot was evaluated using radiography and low field magnetic resonance (MR) imaging. A distal border fragment of the navicular bone, an osseous cyst‐like lesion (OCLL) in the distal third of the navicular bone and focal distal sesamoidean impar desmitis were identified as the most likely causes of pain and lameness. No other lesions likely to contribute to pain and lameness were identified on MR images or gross post mortem examination. The OCLL was characterised histologically by enlarged bone lacunae containing proliferative fibrovascular tissue. Focal lesions of the distal aspect of the navicular bone are rarely found in isolation but can be causes of pain and lameness in horses.     

Skeletal metastasis from a squamous cell carcinoma of the nictitating membrane in a Haflinger horse

A 12-year-old Haflinger gelding with a history of a persistent cough was referred for evaluation of a severe lameness of the left forelimb. An excision of the right nictitans had been performed 2 years prior to presentation, and a squamous cell carcinoma (SCC) with embolic neoplastic cells in several blood vessels had been confirmed by histopathology. The origin of the lameness could not be localised with regional analgesia; therefore, a nuclear scintigraphic examination was performed. This revealed an area of marked increased radiopharmaceutical uptake at the level of the caudodorsal border of the left scapula. Further examination, including ultrasound-guided biopsy of the suspect region, confirmed the presence of SCC invading the scapula. Due to poor a prognosis, the horse was subjected to euthanasia. Prior to euthanasia, the gelding was tested homozygous for the missense variant in the damage-specific DNA-binding protein 2 (DDB2) gene, which is reported as a risk factor for the development of nictitans SCC in Haflinger horses. Post-mortem evaluation revealed multiple SCC metastasis, affecting the scapula, the liver and the lungs. To the authors' knowledge, this is the first reported case of bone metastasis following a primary periocular SCC in a horse.     

Loss of implant-bone interface following distal radial locking-plate endoprosthesis limb-sparing surgery in a dog

An eight-year-old, neutered female Rottweiler was presented with lameness of seven days duration. Radiographs were consistent with a distal radial bone tumour. Limb-sparing surgery was performed using a commercially available endoprosthesis with a locking bone plate. Histopathological examination of the resected bone revealed an intraosseous fibrosarcoma, and postoperative adjuvant chemotherapy was initiated three weeks after surgery. Despite initial satisfactory limb function, lameness worsened four months after surgery. Radiographs revealed large areas of bone lysis around the proximal and distal screws, leading to significant resorption of the radius and radial carpal bone with subsequent construct failure. Further treatment was declined by the owner and the dog was subsequently euthanased. This case illustrates that implant failure is not necessarily averted by the use of locking (compared with non-locking) implants combined with an endoprosthesis to treat distal radial tumours in dogs.