Iatrogenic sciatic nerve injury in eighteen dogs and nine cats (1997-2006)

Objective— To report clinical features associated with iatrogenic peripheral nerve injury in dogs and cats admitted (1997–2006) to a referral teaching hospital.
Study Design— Retrospective study.
Animals— Dogs (n=18), 9 cats.
Methods— Patients had acute signs of monoparesis attributable to sciatic nerve dysfunction that developed after treatment. Neurologic examination and electrodiagnostic testing were performed. Surgical therapy was used for nerve entrapment and delayed reconstructive surgery used in other cases.
Results— Of 27 nerve injuries, 25 resulted from surgery (18 with treatment of pelvic injuries). Iliosacral luxation repair resulted in tibial (4 cats) and peroneal (3 dogs) nerve dysfunction. Other causes were intramedullary pinning of femoral fractures (3), other orthopedic surgery (cemented hip prosthesis [2] and tibial plateau-leveling osteotomy [1]), and perineal herniorrhaphy [1]. Nerve injury occurred after intramuscular injection (1 cat, 1 dog). Immediate surgical treatment was removal of intramedullary nails, extruded cement, or entrapping suture. Delayed nerve transplantation was performed in 2 dogs. Within 1 year, 13 patients recovered completely, clinical improvement occurred in 7, and there was no improvement in 7. Five of the 7 dogs that did not recover had acetabular or ilium fracture.
Conclusion— Iatrogenic sciatic nerve injury occurred most commonly during treatment of pelvic orthopedic diseases and had a poor prognosis. Clinical variation in sciatic nerve dysfunction in dogs and cats can be explained by species anatomic differences.
Clinical Relevance— Iatrogenic sciatic nerve injury leads to severely debilitating locomotor dysfunction with an uncertain prognosis for full-functional recovery.     

Treatment of traumatic dental displacement in dogs: six cases of lateral luxation

In dogs and cats, the most common causes of dental injury are fights with other animals, car accidents, falls from a height, and chewing on hard materials such as bones or rocks. The trauma more often causes fracture of the teeth, but sometimes avulsion or luxation can occur. Avulsion is the complete displacement of the tooth out of the alveolar socket and luxation is the partial displacement of the tooth. Tooth luxation and avulsion represent dental emergencies. Time is an important factor for successful treatment; the prognosis becomes poorer the longer the tooth is out of the socket. This paper describes the guidelines for treatment of dental displacement in cats and dogs and presents six cases of dental lateral luxation in dogs seen at the Veterinary Hospital of the University of Pennsylvania (VHUP) in the period from May 1996 to September 1997.     

Evaluation of Prognostic Factors for Growth Following Distal Femoral Physeal Injuries in 17 Dogs

Seventeen dogs that had incurred Salter Type I or II injuries to the distal femoral physis were evaluated clinically and radiographically for evidence of altered growth of the femur or tibia. Some degree of femoral growth disturbance was found in 82.4% of the dogs; the mean extent of decreased growth was 6.7%. Obvious clinical lameness resulted from the leg length discrepancy in three dogs. Several factors were evaluated statistically as predictors of growth disturbance; the age of the animal at the time of injury appeared to have the most prognostic importance. Factors found not to be as significant were the adult size of the animal, the type of Salter fracture incurred, the displacement of the fracture, the time lag between injury and surgery, and the method of fracture fixation employed. Compensatory overgrowth of the tibia in response to decreased growth of the femur was a rare finding.     

Femoral capital physeal fractures in dogs: 34 cases (1979-1989)

Complications associated with femoral capital physeal (CP) fractures in 34 dogs were evaluated. Fractures were surgically repaired, using divergent K-wires or lag screws; radiographic follow-up was available for 21 CP fractures. In all cases, radiographic abnormalities such as degenerative joint disease and resorption of the femoral neck and/or head were seen. Changes were more severe when fracture occurred at an early age. For 4 of 21 dogs (20%), femoral head and neck excision was performed because of complications associated with CP fracture repair. Prognosis for femoral CP fractures is guarded, although affected dogs should be able to function as pets.     

Electrophysiologic Assessment of Acute Polyradiculoneuropathy in Dogs: Comparison with Guillain-Barré Syndrome in People

Electrophysiologic investigations of motor and sensory nerve as well as ventral nerve root function were performed on 12 dogs with suspected acute canine polyradiculoneuropathy (ACP) at different stages and with different severity of disease. The most reliable electrophysiologic indicators of ACP were electromyographic changes (occurring in 100% of affected dogs), significantly decreased compound muscle action potential amplitudes (in 75, 90, and 100% of affected dogs at all sites along the sciatic/tibial, radial, and ulnar nerves, respectively), increased minimum F-wave latencies (67%), increased F ratios (92%), and decreased F-wave amplitudes (67%). These findings suggest that ACP represents a peripheral motor axonopathy, with demyelination and axonal involvement also occurring in ventral nerve roots. Evidence of peripheral demyelination was present in some dogs although it was overshadowed by the prominent axonopathy. ACP more closely resembles the acute axonal or intermediate forms of Guillain-Barré syndrome in people.     

Pathologic fracture in dogs with suspected or confirmed osteosarcoma

Objective: To evaluate clinical presentation of pathologic fractures associated with suspected or confirmed osteosarcoma in dogs and to assess treatment and survival times. Study design: Case series. Animals: Dogs (n=25) appendicular pathologic fracture. Methods: Medical records (January 1997–May 2008) of dogs with pathologic fracture associated with a suspected or confirmed osteosarcoma were reviewed. Dogs were included if they had radiographic evidence of a pathologic fracture and a presumptive or definitive diagnosis of osteosarcoma. Radiographic details, histopathology, and/or cytology findings were recorded. Overall median survival time (MST) and MST of treated dogs were calculated. Age, sex, breed, and other concurrent treatment were evaluated. Results: Rottweilers, Irish Wolfhounds, and Greyhounds were the most common breeds represented. Most dogs had minor trauma and 60% had lameness preceding the fracture. Most commonly, fractures were nondisplaced with minimal comminution. None of the dogs had radiographic evidence of pulmonary metastases at admission. Immediate (13 dogs; 52%) and delayed (4; 16%) euthanasia were performed. One dog was not treated and died 90 days after diagnosis. Three dogs (12%) were treated by amputation alone, 1 (4%) with amputation and chemotherapy, and 3 (12%) with internal fixation using an interlocking nail. Overall MST was 1 day (range, 0–623 days) and MST of treated dogs was 406.5 days. Histologic confirmation of osteosarcoma was available in all treated dogs and 6 euthanatized dogs. Conclusions: Treatment of pathologic fracture associated with presumptive osteosarcoma should be considered as an option to amputation or euthanasia if owners desire other options.     

Thoracic wall and pulmonary trauma in dogs sustaining fractures as a result of motor vehicle accidents

The records of 267 dogs seen at the University of Minnesota Veterinary Teaching Hospital for fractures resulting from motor vehicle accidents were examined to determine the prevalence and types of thoracic wall and pulmonary trauma associated with such cases. Results were analyzed for type and prevalence of thoracic wall and pulmonary injury, and for the prevalence of such injury in dogs with and without extrathoracic injury, in dogs with fractures of single vs multiple bones, in dogs with single fractures of specific bones, in dogs with fractures in the cranial vs the caudal one half of the body, and in dogs with fractures ipsilateral vs contralateral to thoracic injury. The overall prevalence of thoracic wall and pulmonary trauma was 38.9%; pulmonary contusions, pneumothorax, and fractured ribs were the most common injuries. More than 1 type of thoracic wall or pulmonary injury was diagnosed in 57.7% of the cases. Of the dogs with thoracic injury, 24% also had extrathoracic injuries; 16.5% of dogs without thoracic injury had extrathoracic injuries, not including fractures. Of the dogs with fractures of 1 bone, 36.3% had thoracic injuries. Of the dogs with fractures of more than 1 bone, 42.3% had thoracic injuries. The prevalence of thoracic wall and pulmonary trauma was significantly associated with the site of the fracture (cranial vs caudal and ipsilateral vs contralateral); significant association with the specific bone fractured was also seen for some fractures.     

Controlled, clinical trial assessing saphenous, tibial and common peroneal nerve blocks for the control of perioperative pain following femoro-tibial joint surgery in the nonchondrodystrophoid dog

OBJECTIVE: To determine whether bupivacaine peripheral nerve block of the saphenous, tibial and common peroneal nerves proximal to the femoro-tibial joint reduces peri-operative pain following extracapsular surgical stabilization of cranial cruciate ligament rupture in the nonchondrodystrophoid dog. ANIMALS: Forty-one dogs with naturally acquired femoro-tibial joint instability. Study design Randomized, controlled, clinical trial. METHODS: Dogs diagnosed with suspected cranial cruciate ligament injury based on physical and radiographic evidence were randomly assigned to treatment (bupivacaine) or control (saline) nerve blocks before femoro-tibial joint surgery. Pain scores, skin sensation, pain threshold to incisional pressure, time to first systemic 'rescue' opioid analgesic and total analgesic dose were evaluated for 24 hours. p < 0.05 was considered significant. RESULTS: Treatment dogs had a significantly longer period of cutaneous desensitization than control dogs. There were no significant differences between treatment and control groups for pain score, pain threshold to incisional pressure, or time to first-rescue analgesic. The treatment group received significantly more supplemental analgesics than the control group. CONCLUSIONS: These peripheral nerve blocks were easy to perform and resulted in significant desensitization of the associated nerve autonomous zones, but did not improve post-operative analgesia. CLINICAL RELEVANCE: Clinical benefit was not detected when using this technique for peri-operative pain management following extracapsular cranial cruciate ligament surgical stabilization.     

Use of T-plates for the stabilisation of supra-cotyloid ilial fractures in 18 cats and five dogs.

The use of the AO (Arbeitgemeinschaft für Osteosynthesenfragen) veterinary T-plates (1.5/2 mm and 2.7/3.5 mm) for stabilisation of supracotyloid ilial fractures in 18 cats and five dogs was evaluated in a retrospective study. The distal fragment from the coxofemoral joint ranged from 0.5 cm to 1 cm with a mean distance of 0.85 cm. Twenty out of 23 (87%) ilial fractures healed in original alignment. Three out of 23 (13%) animals had two loosened screws of the distal fragment with fracture malunion and minor medial displacement of the acetabular fragment. Screw or plate breakage was not observed and the implants were not removed. The clinical result was 'excellent' for 18 animals (78%), 'good' for four animals (17%), and 'poor' for one animal (5%). The use of T-plates permits good correction of supracotylo?d fractures with minimal approach and minimizes post-operative complications.     

Locked jaw syndrome in dogs and cats: 37 cases (1998-2005)

A consecutive series of cases of dogs and cats with locked jaw syndrome (inability to open or close the mouth) are reported in this study. Dogs were significantly overrepresented (84.0%) and adult dogs were more frequently affected (81.0%). Temporomandibular joint ankylosis due to fracture was the most common cause (54.0%) of locked jaw syndrome. Additional potential causes of locked jaw syndrome are masticatory muscle myositis, neoplasia, trigeminal nerve paralysis and central neurological lesions, temporomandibular joint luxation and dysplasia, osteoarthritis, retrobulbar abscess, tetanus, and severe ear disease. Treatment of locked jaw is directed towards the primary cause. It is important to treat the tonic spasm in order to minimize periarticular fibrosis. Surgical intervention is recommended for temporomandibular joint ankylosis. Masticatory muscle myositis treatment is initiated by gradually opening the mouth, with medical treatment based on immunosuppressive therapy. Fracture and masticatory muscle myositis are associated with a relatively good prognosis in regard to short-term outcome as compared to animals with central neurologic lesions or osteosarcoma which have a poor prognosis.     

Use of flexible intramedullary rods for fixation of femoral fractures in eight dogs

High-density, polysulfone rods were used to repair 4 comminuted and 4 short-oblique, mid-diaphyseal femoral fractures in 8 dogs. Bony union was achieved in 2 dogs at 10 and 12 weeks after surgery. In one dog, the femoral fracture was healing when amputation of the limb became necessary because of sciatic nerve damage secondary to an ipsilateral pelvic fracture. In a fourth dog, fracture repair resulted in nonunion, despite normal clinical function at 18 months after surgery. In the remaining 4 dogs (50%), the rods failed at 3.5, 4, 6, and 22 weeks after surgery. These fractures were then stabilized by use of other methods. Although several factors may have contributed to failure of the rods, multiple autoclaving of the thermoplastic implants may have caused embrittlement and subsequent breakage.     

Surgical and oncologic outcomes in dogs with malignant peripheral nerve sheath tumours arising from the brachial or lumbosacral plexus

Malignant peripheral nerve sheath tumours (MPNST) of a plexus nerve or nerve root cause significant morbidity and present a treatment challenge. The surgical approach can be complex and information is lacking on outcomes. The objective of this study was to describe surgical complication rates and oncologic outcomes for canine MPNST of the brachial or lumbosacral plexus. Dogs treated for a naïve MPNST with amputation/hemipelvectomy with or without a laminectomy were retrospectively analysed. Oncologic outcomes were disease free interval (DFI), overall survival (OS), and 1- and 2-year survival rates. Thirty dogs were included. The surgery performed was amputation alone in 17 cases (57%), and amputation/hemipelvectomy with laminectomy in 13 cases (43%). Four dogs (13%) had an intraoperative complication, while 11 dogs (37%) had postoperative complications. Histologic margins were reported as R0 in 12 dogs (40%), R1 in 12 dogs (40%), and R2 in five dogs (17%). No association was found between histologic grade and margin nor extent of surgical approach and margin. Thirteen dogs (46%) had recurrence. The median DFI was 511 days (95% CI: 140–882 days). The median disease specific OST was 570 days (95% CI: 467–673 days) with 1- and 2-year survival rates of 82% and 22% respectively. No variables were significantly associated with recurrence, DFI, or disease specific OST. These data show surgical treatment of plexus MPNST was associated with a high intra- and postoperative complication rate but relatively good disease outcomes. This information can guide clinicians in surgical risk management and owner communication regarding realistic outcomes and complications.     

Surgical treatment of shoulder instability. A retrospective study on 76 cases (1993-2007)

This study evaluates 76 cases of shoulder instability in dogs, functional outcome after treatment, and the effectiveness of medial biceps tendon transposition using a metallic staple. Clinical examinations of the shoulder were performed and radiographs were taken. Conservative treatment or surgery (biceps tendon transposition or arthrodesis) was then opted for on the basis of type of instability, associated lesions and dog (age, weight, behaviour). Long-term functional outcome was categorized as 'excellent', 'good', 'average' or 'poor'. In our series, the most frequently affected breed was the Poodle (13%). Humeral head intermittent displacement was either medial (80%), lateral (19%) or cranial (1%). On clinical examination, 97% of the animals experienced pain. In anaesthetised dogs, shoulder instability was observed in 90% of the population. Muscle atrophy (33%) and associated radiographic lesions (34%) were less frequent. Ninety-five percent of the dogs were treated surgically, either by bicipital tendon transposition (81%) or by shoulder arthrodesis (19%). Results were 'good' to 'excellent' in 25% of the animals treated conservatively, and in 84.5% and 87.5%, respectively, in those treated by tendon transposition and arthrodesis. Complications did not arise from the use of a metallic staple to anchor the tendon during medial transposition. Tendon transposition or arthrodesis resulted in a good functional outcome in more than 80% of the dogs with shoulder instability. During the medial transposition, the biceps tendon was easily and effectively stabilized using a metallic staple.     

Intramedullary interlocking nail stabilisation of 21 humeral fractures in 19 dogs and one cat

OBJECTIVE: To assess the suitability of the intramedullary interlocking nail to stabilise humeral diaphyseal fractures in dogs and cats. METHOD: This multi-centre study retrospectively examined medical records, between June 1994 and May 2001, of 19 dogs and one cat, in which a total of 21 humeral fractures were stabilised with intramedullary interlocking nails. RESULTS: Animals ranged in body-weight from 4 to 97 kg. Eighteen (86%) of the fractures were comminuted. Adjunctive stabilisation was used in twelve (57%) fractures and bone grafts in nine (43%) fractures. A rapid return of function was noted in the majority of animals, with 14 (67%) having good or excellent function within four days of surgery. In two fractures the repair collapsed when a single proximal transcortical screw was placed cranial to the tricipital line of the humerus. This suggests that if a single transcortical screw is placed proximally the screw should be distal or caudal to the tricipital line in order to engage sufficient cortical bone. Eighteen (86%) of the fractures healed when stabilised with intramedullary interlocking nails. Three fractures did not heal. One was in a dog where a pathological fracture was temporarily stabilised with an intramedullary interlocking nail, one in a dog that died of an abdominal crisis three weeks after surgery and one in a dog in which fracture stabilisation collapsed due to incorrect implant selection. CONCLUSION: Intramedullary interlocking nails are well suited to the stabilisation of humeral diaphyseal fractures in dogs and cats.     

MAGNETIC RESONANCE IMAGING OF ACQUIRED TRIGEMINAL NERVE DISORDERS IN SIX DOGS

The medical records and magnetic resonance (MR) images of dogs with an acquired trigeminal nerve disorder were reviewed retrospectively. Trigeminal nerve dysfunction was present in six dogs with histologic confirmation of etiology. A histopathologic diagnosis of neuritis (n=2) or nerve sheath tumor (n=4) was made. Dogs with trigeminal neuritis had diffuse enlargement of the nerve without a mass lesion. These nerves were isointense to brain parenchyma on T1-weighted (T1W) precontrast images and proton-density-weighted (PDW) images and either isointense or hyperintense on T2-weighted (T2W) images. Dogs with a nerve sheath tumor had a solitary or lobulated mass with displacement of adjacent neuropil. Nerve sheath tumors were isointense to the brain parenchyma on T1W, T2W, and PDW images. All trigeminal nerve lesions enhanced following contrast medium administration. Atrophy of the temporalis and masseter muscles, with a characteristic increase in signal intensity on T1W images, were present in all dogs.     

Development and verification of saphenous, tibial and common peroneal nerve block techniques for analgesia below the thigh in the nonchondrodystrophoid dog

OBJECTIVE: To document simple and reliable local, infiltrating nerve blocks for the saphenous, tibial and common peroneal nerves in the dog. STUDY DESIGN: Laboratory technique development; in vivo blind, controlled, prospective study. ANIMALS: Twenty canine cadavers and 18 clinically normal, client-owned dogs. METHODS: A peripheral nerve blockade technique of the tibial, common peroneal, and saphenous nerves was perfected through anatomic dissection. Injections were planned in the caudal thigh for the tibial and common peroneal nerves, and in the medial thigh for the saphenous nerve. Cadaver limbs were injected with methylene blue dye and subsequently dissected to confirm successful dye placement. Clinically normal dogs undergoing general anesthesia for unrelated, elective procedures were randomly assigned to treatment (bupivacaine; n = 8) or control (saline; n = 8) nerve blocks of the nerves under study. Upon recovery from general anesthesia, skin sensation in selected dermatomes was evaluated for 24 hours. RESULTS: Cadaver tibial, common peroneal, and saphenous perineural infiltrations were successful in nonchondrodystrophoid dogs (100, 100, and 97%, respectively.) Intraneural injection was rare (1%; 1/105; tibial nerve) in cadaver dogs. In the treatment group of normal dogs, duration of loss of cutaneous sensation in some dermatomes (saphenous, superficial and deep peroneal nerve) was significantly different than control dogs; the range of desensitization occurred for 1-20 hours. No clinical morbidity was detected. CONCLUSIONS: This technique for local blockade of the tibial, common peroneal, and saphenous nerves just proximal to the stifle is easy to perform, requires minimal supplies and results in significant desensitization of the associated dermatomes in clinically normal, nonchondrodystrophoid dogs. CLINICAL RELEVANCE: This technique may be an effective tool for post-operative analgesia to the femoro-tibial joint and distal pelvic limb. Other applications, using sustained-release drugs or methods, may include anesthesia/analgesia in high-risk patients or as a treatment for chronic pelvic limb pain or self-mutilation.     

Dual-Energy X-Ray Absorptiometry and Force-Plate Analysis of Gait in Dogs With Healed Femora After Leg-Lengthening Plate Fixation

Dual-energy x-ray absorptiometry was used to measure bone mineral density of four regions in healed femora of nine dogs after fracture fixation with a leg-lengthening plate. Six to 85 months (mean, 46 months) after surgery, the bone mineral density of healed femora was not significantly different from the contralateral uninjured femora ( P >.05; power = 0.8 at Δ= 15%). Radio-lucencies around the proximal screws, apparently associated with screw loosening, were seen on radiographic views of the healed femora of three dogs. In one of these dogs, one screw in the proximal metaphysis had broken. Force-plate analysis of gait was also performed on dogs at the time of bone mineral density measurement. Peak vertical force was decreased in the pelvic limb with the healed fracture compared with the contralateral unoperated limb ( P < 0.05). Clinically apparent lameness in three dogs did not appear to be associated with altered bone mineral density and may have been caused by hip osteoarthritis, a nondisplaced hairline diaphyseal fracture, and screw loosening in conjunction with extensive post-traumatic soft tissue injury.     

Stress Fractures of the Acetabulum in 26 Racing Greyhounds

Acetabular fractures in 26 racing Greyhounds were reviewed. All fractures occurred during racing or training and were unrelated to any external trauma. All fractures had similar configurations, were minimally displaced, and involved only the acetabulum. Affected dogs were young (16-36 months). Fractures occurred unilaterally (22 dogs) and bilaterally (4 dogs). There was no sex predilection, and both right and left sides were equally represented. Bilateral fractures were associated with retraining between the occurrence of the first and second fractures. Radiographically, a fracture line was consistently visible in the caudal third of the acetabulum. Fractures in gross specimens resembled an inverted "Y." Results of histologic evaluation of two fractured acetabula showed changes characteristic of a nonunion fracture. Microfractures were evident in the grossly normal acetabulum opposite the fractured side. Evidence obtained from this study suggests a common pathogenesis of the fractures related to tremendous repetitive stresses produced during running. Greyhounds with unilateral acetabular fractures may provide a reproducible model for future studies of stress fractures in animals and humans because of the high incidence of bilateral fractures that develop during retraining. Surgical repair of the acetabular stress fracture was more successful than conservative management in returning the dogs to competitive racing.     

Results of Screw/Wire/Polymethylmethacrylate Composite Fixation for Acetabular Fracture Repair in 14 Dogs

Objective- To assess the clinical results in dogs with acetabular fractures stabilized using a screw-wire-polymethylmethacrylate (SWP) composite fixation.
Study Design- A retrospective study of client-owned dogs with acetabular fractures.
Animals- Fourteen dogs ranging in age from 4 to 95 months (mean, 34 ±25 months; median, 25 months) and body weight from 8 to 39 kg (mean, 25 ±6 kg; median, 27 kg).
Methods- Medical records and radiographs were retrospectively evaluated to determine location of the fracture, presence of preexisting degenerative joint disease, accuracy of fracture reduction and complications associated with surgery. Long-term results were evaluated by subjective assessment of lameness, elicitation of pain and/or crepitus on manipulation of the coxofemoral joint, measurements of pelvic limb circumference, coxofemoral joint goniometric measurements, and radiographic evaluation.
Results- Fracture reduction was considered anatomic in 13 dogs. At the time of the last follow-up evaluation (mean, 347 ±261 days; median, 380 days) 10 dogs were sound on the affected limb, three dogs had a subtle weight-bearing lameness of the affected limb, and the remaining dog had a consistent non-weight-bearing lameness of the affected limb. Mild (n = 10) or moderate (n = 1) degenerative changes of the affected coxofemoral joint attributed to the acetabular fracture and its repair were noted on the follow-up radiographs in 11 dogs. Limb circumference of the affected limb ranged from -8.2% to +10.8% (mean, -0.8 ±4.2%; median, -0.7%) of the contralateral limb.
Conclusions- The SWP composite fixation consistently maintained anatomic reduction, was associated with few complications, and yielded satisfactory clinical results.
Clinical Relevance- The SWP composite fixation technique would seem to be an acceptable means of stabilizing acetabular fractures in dogs.     

Dynamic intramedullary crosspinning technique for repair of distal femoral fractures in dogs and cats: 71 cases (1981-1985)

Dynamic intramedullary crosspinning was used in the surgical treatment of supracondylar and distal physeal fractures of the femur in 129 dogs and cats over a 5-year period; the records of the 44 dogs and 27 cats with follow-up information up to time of bony union were evaluated. The results were good or excellent in 66 of 71 animals (93%). The mean follow-up period was 22 months. Distal pin migration was the major complication (10 animals; 14%). The pin migrated before bony union in 2 animals because of instability and collapse at the fracture site. The pin migrated in 8 animals after bony union and was associated with intermittent lameness. In 5 of these, pin removal was performed and the lameness resolved.