Evaluation of Closed Reduction and Screw Fixation in Lag Fashion of Sacroiliac Fracture‐Luxations

Objective— To evaluate outcome by radiographic assessment after closed reduction and percutaneous screw fixation in lag fashion of sacroiliac fracture‐luxations in dogs. Study Design— Retrospective study. Animals— Dogs (n=24) with sacroiliac fracture‐luxations. Methods— Medical records (1999–2006) and radiographs of 24 dogs (29 fracture‐luxations) that had stabilization of sacroiliac fracture‐luxation by fluoroscopic‐guided closed reduction and percutaneous screw fixation in lag fashion were reviewed. Signalment, body weight, number, and location of all concurrent injuries and implants used for repair were recorded. Radiographs were used to evaluate the accuracy of screw placement in the sacral body, screw depth/sacral width ratio, reduction of the sacroiliac joint, pelvic canal diameter, and hemipelvic canal width. Radiographic re‐examination (range, 4 to >8 weeks postoperatively) was available for evaluation. Results— Mean screw depth/sacral width ratio on immediate postoperative and re‐examination radiographs was 64% and 61%, respectively. Mean percentage reduction of the sacroiliac joint on immediate postoperative and re‐examination radiographs were 91% and 87%, respectively. Pelvic canal diameter ratio demonstrated successful restoration of the pelvic canal. Hemipelvic canal width ratio documented successful closed reduction repair independent of concurrent pelvic injuries. Conclusion— Successful repair of sacroiliac fracture‐luxations, determined by radiographic assessment, can be achieved by fluoroscopic‐guided closed reduction and percutaneous screw fixation in lag fashion. Clinical Relevance— Fluoroscopic‐guided closed reduction and percutaneous screw fixation in lag fashion of sacroiliac fracture‐luxations is a minimally invasive technique that restores and maintains pelvic canal dimensions and should be considered as an alternative to open reduction or nonsurgical management of sacroiliac fracture‐luxations.     

Closed Reduction and Lag Screw Fixation of Sacroiliac Luxations and Fractures

OBJECTIVE: To describe a technique for closed reduction and percutaneous insertion of a lag screw for fixation of sacroiliac fracture-luxations, and to report the success of this technique in stabilizing sacroiliac fracture-luxations. STUDY DESIGN: A retrospective clinical study. STUDY POPULATION: 13 consecutive client-owned dogs with sacroiliac fracture-luxations. METHODS: Sacroiliac fracture-luxations were stabilized by using a closed reduction and percutaneous lag screw fixation technique. Preoperative, postoperative, and last re-examination radiographs were used to assess the location and number of pelvic injuries, other orthopedic injuries, percent reduction of the sacroiliac joint, percent sacral width screw depth, position of the screw, pelvic canal diameter ratio, hemipelvic canal width ratio, and complications. Information on signalment, weight, weight-bearing status, neurologic status, and complications was obtained from the medical record. RESULTS: Mean percent reduction of the sacroiliac joint was 92.33%. All screws were placed within the sacral body with a mean screw depth/sacral width of 79.03%. No screw loosening occurred. Mean pelvic canal diameter ratios were 0.99, 1.20, and 1.14 preoperatively, immediately postoperatively, and at the last re-examination, respectively. Nine of 13 dogs were willing to walk on the ipsilateral rear leg the day after surgery. CONCLUSIONS: Closed reduction and percutaneous insertion of a lag screw for stabilization of fracture-luxation of the sacroiliac joint is an acceptable method of repair. CLINICAL RELEVANCE: Sacroiliac fracture-luxations can be successfully reduced and stabilized using a minimally invasive technique.     

Internal fixation of femoral capital physeal injuries in dogs: 40 cases (1979-1987)

Fractures of the femoral capital physis were stabilized with small pins or a lag screw in 36 dogs (4 bilateral injuries). Radiography was used to monitor the development of osteoarthritis in affected joints and narrowing of the femoral neck. More radiographic signs of arthritis (P less than 0.05) developed in the coxofemoral joints of dogs that were less than or equal to 4 months old when injured, compared with those in dogs greater than 4 months old. Of 40 capital physeal injuries, 35% had concurrent ipsilateral coxofemoral joint injuries and developed more radiographic signs of arthritis (P less than 0.05) than did those that had no other coxofemoral injury. Narrowing of the femoral neck developed in 70% of the healing capital physeal repairs, but in most dogs, narrowing was not associated with segmental collapse of the femoral neck. Neither time interval from injury to surgical fixation nor surgical approach used had an effect (P greater than 0.05) on the development of narrowing of the femoral neck.     

Partial carpal and pancarpal arthrodesis in the dog: a review of 50 cases

Fifty-six carpal arthrodeses were carried out in 50 dogs. Six of these had bilateral arthrodeses. A dynamic compression plate (DCP; Straumann Great Britain Ltd), placed on the dorsal aspect of the carpus, was used for fixation in all cases. The main indication for pancarpal arthrodesis was a hyperextension injury of the radiocarpal joint. Forty-three pancarpal arthrodeses were performed in 40 dogs (a bilateral procedure was performed in three). Hyperextension injuries of the intercarpal and carpometacarpal joints were treated by partial carpal arthrodesis in 10 dogs; three of these had bilateral procedures. Seventy-four per cent of dogs treated by pancarpal arthrodesis regained full limb function. Only 50 per cent of cases treated by partial carpal arthrodesis had a similar result.     

Sacral fractures in dogs and cats: a classification scheme and review of 51 cases

classification scheme for sacral fractures was based on a review of sacral fractures in 34 dogs and 17 cats. They were classified into five categories based on their radiographic appearance on standard lateral and ventrodorsal radiographs of the pelvis. Concomitant pelvic injuries were commonly observed: 32 per cent of dogs had a fracture of an ilium and 65 per cent of cats had unior bilateral sacroiliac subluxation. Neurological deficits were common where the fractures traversed the spinal canal or sacral foraminae. Comparison is made between sacral fractures in dogs and cats, and humans.     

Stabilization of Sacroiliac Luxation in 40 Cats Using Screws Inserted in Lag Fashion

Objective: To (1) identify prognostic indicators for stability after stabilization of sacroiliac luxation with screws inserted in lag fashion and (2) report dorsoventral dimensions of the sacrum in cats. Study Design: Multicenter retrospective study. Sample Population: Cats (n=40) with sacroiliac luxation. Methods: Case records and radiographs of cats presented at the Queen's Veterinary School Hospital Cambridge and the Royal Veterinary College Hatfield for screw fixation of sacroiliac luxation were reviewed. Dorsoventral dimensions of 15 feline cadaveric sacral bodies were measured to identify the appropriate implant size for use in fixation with screws inserted in lag fashion. Results: Of 40 cats, 13 had left, 14 right, and 13 bilateral sacroiliac luxations. Of 48 screws analyzed, 42 (87.5%) were placed within the sacral body or exited ventrally and 6 (12.5%) were considered malpositioned. Screw purchase within the sacrum was statistically different between unstable and stable repairs (P=.001). Using confidence intervals for screw length within the sacrum and effect on stability, the lowest screw depth that contained 95% of the screws that did not loosen was ∼60% of the sacral width. Mean dorsoventral sacral dimension at its narrowest point was 5.9±1.14 mm. There was no significant difference in the incidence of implant loosening between those luxations that were 100% reduced and those that were <100% reduced (P=.7837). Conclusions: Screw purchase within the feline sacrum of at least 60% of the sacral width significantly reduces the risk of loosening. Clinical Relevance: Screw placement to a depth of 60% of the width of the feline sacrum is recommended.     

Canine sacroiliac luxation: anatomic study of dorsoventral articular surface angulation and safe corridor for placement of screws used for lag fixation

OBJECTIVE: To define a safe corridor in the dorsoventral plane to facilitate placement of screws inserted in lag fashion within the sacral body for fixation of sacroiliac fracture-luxation injuries in dogs. STUDY DESIGN: Anatomic study. SAMPLE POPULATION: Cadaveric canine sacra. METHODS: Canine sacra (n=45) were used for a radiographic study to define a safe corridor in the dorsoventral plane for placement of screws inserted in lag fashion for fixation of sacroiliac luxation in the dog. The defined safe corridor allowed drilling to a depth of 65% of the sacral width to ensure screw purchase of > or =60%. Effects of positioning and measurement techniques were evaluated. RESULTS: Eighty-seven safe corridors were measured. The mean articular surface was 100+/-4.52 degrees from horizontal. Mean maximum, optimum, and minimum safe corridor drill angles were 111+/- 4.57 degrees, 100+/-4.70 degrees, and 89+/-5.17 degrees, respectively, from the articular surface. Predicted surgeon error of +/-4 degrees was used to define the safe corridor for use clinically. CONCLUSIONS: In 91% of sacra, a drill angle of 100+/-4 degrees would remain ventral to the vertebral canal. Twelve sacra (14%) were at risk of penetration of the pelvic canal. A drill angle of 97+/-4 degrees avoids penetration of the vertebral canal in all sacra measured but risks ventral exit from the body in 30% of sacra studied. CLINICAL RELEVANCE: A drill angle of 97 degrees from the articular surface is recommended for insertion of screws for lag fixation of canine sacroiliac luxation.     

Limited open reduction and stabilization of sacroiliac fracture-luxations using fluoroscopically assisted placement of a trans-iliosacral rod in five dogs

Objective— To describe percutaneous fluoroscopically assisted placement of a trans-iliosacral rod to stabilize sacroiliac fracture-luxations after limited open reduction.
Study Design— Retrospective clinical case series.
Animals— Dogs (n=5) with sacroiliac fracture-luxations.
Methods— Medical records and radiographs were reviewed to evaluate implant placement, fracture reduction, pelvic canal diameter ratio, maintenance of reduction, implant stability, assessment of union, and to identify any complications. Owners were contacted to obtain long-term assessment of limb function.
Results— Dogs weighed between 6 and 31 kg. Trans-iliosacral rods were placed correctly traversing the sacral body. Mean (±SD) percent reduction of the sacroiliac joint was 92.9±6.6%. Pelvic canal diameter ratio did not differ significantly between time periods. With the exception of 1 dog, which died in the early postoperative period, all sacroiliac fracture-luxations healed without appreciable complications. Three dogs were sound and 1 dog had a subtle lameness at final physical and radiographic examination (mean±SD: 217±205 days). Owners assessed their dog's limb function (mean±SD: 355±205 days) as good or excellent.
Conclusions— Trans-iliosacral rods can be accurately placed using intraoperative fluoroscopy after limited open reduction of sacroiliac fracture-luxations. Trans-iliosacral rods provided bilateral secure fixation, allowed early weight-bearing and dogs consistently had good long-term clinical results.
Clinical Relevance— Trans-iliosacral rods are suitable implants for the stabilization of sacroiliac fracture-luxations, particularly in dogs with bilateral fracture-luxations and/or concurrent musculoskeletal injuries.     

Biceps Brachii and Brachialis Tendon of Insertion Injuries in Eleven Racing Greyhounds

Objective— To report injuries of the biceps brachii (BTI) or brachialis (BrTI) tendons of insertion in 11 racing Greyhounds.
Study Design— Case series.
Animals— Greyhounds (n=11).
Methods— Medical records (1990–2006) of racing Greyhound dogs with BTI injuries were reviewed. Preinjury, injury, and posttreatment information was obtained via trainer telephone questionnaire and individual greyhound race data. Outcomes between surgical and conservative management were compared.
Results— Dogs had elbow hyperextension, positive biceps test, and forelimb circumduction and 82% were male, whereas Queensland's male to female ratio of racing Greyhounds was almost equal. Eight dogs had right BTI injuries. Nine dogs had surgically confirmed tendon injuries: 5 combined BTI and BrTI, 2 mid-body BTI, 1 musculotendinous BTI, and 1 ulnar tuberosity avulsion fracture. Seven dogs were treated surgically (3 loop pulley sutures, single radial screw and washer, suture screws or fracture fixation in lag fashion), 2 dogs were euthanatized at surgery, 2 were rehomed and hence managed conservatively. All surgically treated dogs returned to near preinjury performance; 6 returned to racing and at least 4 won races in the same or higher grade. One conservatively managed dog returned to "pet" function. No dog reinjured its BTI or BrTI.
Conclusion— BTI and BrTI avulsions are rare acute traumatic performance injuries of racing Greyhounds.
Clinical Relevance— Preinjury racing performance can be achieved with early surgical repair of BTI and BrTI and optimal postoperative management.     

Risk factors for screw migration after triple pelvic osteotomy

The objective of this retrospective study was to identify risk factors for screw migration after triple pelvic osteotomy (TPO) in clinical patients. The medical records, radiographs made immediately after surgery, and follow-up radiographs documenting a healed osteotomy were reviewed for 52 dogs treated with unilateral TPO and 38 dogs treated with bilateral TPO. Signalment, surgeon expertise, length of surgery, sequence of surgery in dogs treated bilaterally, use of ischial or ilial wires or both, screw depth in the sacrum, and screw migration were documented for each of the 128 pelvic osteotomies. Screws placed in the first and second plate hole, securing the cranial portion of the plate, loosened most frequently. Factors associated with decreased screw migration included use of an ischial hemicerclage wire and increased depth of sacral purchase with the first and second cranial screws.     

Veterinary qualifications and the right to practise in the EEC: an analysis of the directives.

The urogenital system was involved in 92 (22.9 per cent) of 401 malformed lambs examined over a three year period; genital 69 (six males: one female) and urinary 23 (three males: one female). Ten lambs had both genital and urinary defects. Sixty-eight (73.0 per cent) of the 92 lambs had defects of other organs, the most common being atresia ani, various skeletal and central nervous system defects, and arthrogryposis. The most common external defect of the male genital system was partial to complete cleft of the scrotum and the most common internal defect was cryptorchidism (six unilateral and 12 bilateral). Both penile agenesis and diphallia were observed twice. Defects of the female genital system included two uterine agenesis, four atresia vaginam, and one freemartin. Male pseudohermaphroditism was found in three lambs. The most common external urinary defect was male hypospadias and the most common internal defect was renal agenesis (12 unilateral and one bilateral). Other urinary defects were hydronephrosis (two unilateral and two bilateral), cystic kidneys (four unilateral and two bilateral), one bilateral polycystic kidneys, one patent urachus and six dysgenic kidneys.     

Repair of femoral trochanteric osteotomy in the dog

The records and radiographs of 24 dogs that underwent femoral trochanteric osteotomy repair were reviewed. Osteotomy repair was performed with either a pin and tension band wire or a lag screw technique. Significant clinical complications associated with the osteotomy were identified in one dog (4 per cent) six weeks after surgery, although abnormal radiographic changes were evident in 15 dogs (62 per cent). The method of repair did not influence healing and there were comparable radiographic complication rates. It Is concluded that femoral trochanteric osteotomy Is not associated with significant clinical problems, despite a high incidence of abnormal radiographic findings.     

Surgical Repair of Mid‐body Proximal Sesamoid Bone Fractures in 25 Horses

Objective— To describe the characteristics of unilateral mid‐body proximal sesamoid bone (PSB) fractures, to determine factors associated with the outcome of horses after surgical repair, and to describe a technique for arthroscopically assisted screw fixation in lag fashion. Study Design— Retrospective case series. Animals— Horses (n=25) with unilateral mid‐body PSB fracture. Methods— Medical records (1996–2006), radiographs, and arthroscopic videos of horses with surgically repaired unilateral mid‐body PSB fractures were reviewed. Retrieved data included signalment, affected limb and PSB, fracture characteristics, and surgical technique. Outcome was established by radiographic assessment of healing and race records; categorical data were analyzed using Fisher's Exact test. Results— Medial forelimb PSBs were most commonly affected (80%). Surgical technique and degree of reduction were significantly associated with outcome; 44% of horses with screw repair and none of the horses with wire fixation raced (P=.047). Factors that may have influenced this outcome were differences in fracture reduction (improved reduction in 22% wire repairs and 88% screw repairs, P=.002) and use of external coaptation (22% wire repair and 88% lag screw repair, P=.002). None of the horses with unimproved reduction raced after surgery. Conclusions— Only 28% of horses with mid‐body PSB fractures raced after surgery. Compared with wire fixation, screw fixation in lag fashion resulted in good reduction and is seemingly a superior repair technique. Clinical Relevance— For mid‐body PSB fractures, arthroscopically assisted screw fixation in lag fashion and external coaptation for anesthesia recovery and initial support provides the best likelihood of return to athletic use.     

Diagnostic accuracy of positive contrast computed tomography arthrography for the detection of injuries to the medial meniscus in dogs with naturally occurring cranial cruciate ligament insufficiency

O bjective : To assess the usefulness of computed tomography arthrography of the stifle in diagnosing meniscal tears in dogs with cranial cruciate ligament insufficiency.
M ethods : A prospective clinical study was performed. Dogs were included if they had evidence of cranial cruciate ligament insufficiency or persistent or recurrent lameness following surgery for cranial cruciate ligament insufficiency. Dogs were sedated for a computed tomography scan of the affected stifle, orientated in the dorsal plane. A survey computed tomography scan was followed by a computed tomography arthrogram. A stifle arthrotomy was performed, and the surgical findings were recorded. The computed tomography scans were reviewed by three blinded reviewers, and the results were compared to the surgical findings.
R esults : Twenty-one computed tomography arthrograms from 20 dogs were included. At surgery, damage to the medial meniscus was identified in 14 stifles. Initial interpretation of computed tomography arthrography images was 57 to 64 per cent sensitive and 71 to 100 per cent specific for diagnosing medial meniscal injuries. Interpretation of the images on retrospective analysis was 71 per cent sensitive and 100 per cent specific, with an accuracy of 0·857.
C linical S ignificance : The accuracy of stifle computed tomography arthrography for the diagnosis of tears to the medial meniscus was found to be good. It is a minimally invasive and repeatable technique, which does not require general anaesthesia or specialist training to obtain the images. The ability to reliably diagnose meniscal injury without the need for surgery may be advantageous, particularly in dogs which had previously had surgery for cranial cruciate ligament insufficiency.     

Ventral abdominal approach for screw fixation of sacroiliac luxation in clinically affected cats

OBJECTIVE: To investigate sacroiliac luxation repair with positional screw insertion from the ventral surface of the sacral wing via a ventral abdominal approach in cats. ANIMALS: 18 European shorthair cats. PROCEDURES: All cats underwent clinical examination including orthopedic and neurologic examination and assessment of lameness and pain before and immediately after surgery and 6 and 16 weeks after surgery. All sacroiliac luxations were stabilized with a single positional 2.4-mm cortical titanium self-tapping screw. The pelvic floor was also repaired in selected cats. Screw entry points and angles determined in a prior study of cadavers were used. Radiographs were taken before surgery and during follow-up evaluations to assess postoperative sacroiliac luxation reduction, implant placement, and repair stability. RESULTS: All implants were placed correctly. Iatrogenic sciatic nerve injuries occurred in 2 cats. Median time to ambulation was 1.5 days for cats with sacroiliac luxation as the sole injury. Radiographic outcome of sacroiliac luxation repair was excellent in 15 of 17 repairs, good in 1 of 17 repairs, and poor in 1 of 17 repairs. Clinical outcome was excellent in 11 of 15 cats and good in 4 of 15 cats. CONCLUSIONS AND CLINICAL RELEVANCE: Insertion of a positional screw across the sacroiliac joint via a ventral abdominal approached can be an alternative to conventional techniques of sacroiliac luxation repair in cats. This novel technique allowed repair of bilateral sacroiliac luxation, repair of pelvic floor fractures, and treatment of soft tissue injuries of the abdominal cavity or abdominal organs with a single approach.     

Management of 49 antebrachial and crural fractures in dogs using circular external fixators

Objectives : To evaluate frame constructs, postoperative fracture reduction, postoperative care, complications, treatment duration and outcome of circular external fixation for management of 49 antebrachial and crural fractures in dogs. Methods : Medical records of dogs that underwent surgery with circular external fixation were examined for fracture location, frame configuration, postoperative fracture reduction, treatment duration, complications and outcome. Results : Forty‐nine fractures in 48 dogs were stabilised using circular external fixation. Frame removal occurred on average 61 days after surgery (median±sd, 52±30 days). Minor complications were observed in 35 cases (71 per cent) and major complications in seven (14 per cent). Radiographic outcome at frame removal was judged as excellent in 18 cases (37 per cent), as good in 26 (53 per cent), as fair in four (8 per cent) and poor in one (2 per cent). After frame removal, one fracture was stabilised with a plate, and eight patients were lost to follow‐up. Functional and cosmetic outcome at follow‐up was judged as excellent in 32 cases (80 per cent), good in seven (18 per cent) and fair in one (2 per cent). Clinical Significance : Circular external fixation can effectively treat antebrachial and crural fractures in dogs, even geometrically complex fractures. Minor complications are frequent but easily managed in most instances. Healing time is comparable to that of other external fixation methods.     

Total ear canal ablation and lateral bulla osteotomy in the dog

One hundred total ear canal ablation/lateral bulla osteotomy procedures were performed in 71 dogs over a four year period. The main indication for surgery was advanced disease of the aural canal or middle ear resulting from prolonged inflammatory disease of the outer ear. Complications of surgery included facial nerve injury, inner ear injury, retroglenoid vein haemorrhage and wound dehiscion. The incidence of complications (29 per cent) was, however, substantially lower than has previously been recorded following this procedure. Meticulous dissection technique and increasing familiarity with the procedure were thought to be responsible for lower complication rates than have previously been recorded. Surgery was considered to have resolved the original aural condition in 92 per cent of cases and only infrequently resulted in complete loss of hearing function.     

Use of laparotomy in a staged approach for resolution of bilateral or complicated perineal hernia in 41 dogs

OBJECTIVE: To evaluate the value of laparotomy as the initial step in the treatment of bilateral or complicated perineal hernia (PH) in dogs. STUDY DESIGN: Retrospective study. ANIMALS OR SAMPLE POPULATION: Forty-one dogs with PH. METHODS: Dogs with bilateral or complicated PH treated by a 2-step approach between November 1997 and December 2001 were studied. Inclusion criteria for complicated PH were: recurrence of PH, unilateral PH with a major rectal dilatation, PH with a concurrent surgical prostatic disease, and PH with retroflexed bladder. Colopexy, vas deferens pexy, cystopexy, and prostatic omentalization were performed during laparotomy as needed. Later, PH was performed by internal obturator muscle flap (IOMF) or if there was a perineal rent or weakness on the contralateral side, appositional herniorrhaphy was performed. Outcome was followed for >/=6 months. RESULTS: PH were bilateral (20 dogs) or unilateral (21). Twenty-one (51%) dogs had prostatic disease (clinical or ultrasonography diagnosis; 17 confirmed histologically) and 12 (29%) had urinary bladder retroflexion. Forty-one colopexies, 32 vas deferens pexies, 6 cystopexies, and 9 prostatic surgeries (omentalization or perineal cyst resection) were performed. PH was performed 2-20 days (median, 6 days) later: 61 IOMF transpositions, 13 appositional. Mean follow-up time was 26.6 months (range, 6-54 months, median, 27 months). PH was resolved in 37 (90%) dogs; 4 dogs had recurrence, and all occurred within 6 months. Thirty-eight (92%) dogs had an improved quality of life (good in 34 dogs, fair in 4 dogs). Wound complications occurred in 7 dogs (17%). Postoperative urine dribbling occurred in 15 dogs (37%) and was irreversible in 7 dogs (17%). Postoperative fecal straining persisted in 18 dogs (44%), and was permanent in 4 dogs (10%). Fecal incontinence did not occur. CONCLUSIONS: In bilateral or complicated PH, fixation of the urinary bladder and colon, and treatment of prostatic disease increase the chances of resolution. Emptying of the perineal space by organ pexy allows improved observation during herniorrhaphy. Despite a 90% clinical resolution, dogs with complicated PH treated by a 2-step protocol may have persistent urinary and fecal disorders. CLINICAL RELEVANCE: To improve the prognosis of bilateral or complicated PH, investigation and treatment of concomitant lesions (rectal, prostatic, bladder) should be part of a rational surgical strategy using a 2-step protocol.     

Radial carpal bone fractures in 15 dogs

Between 1977 and 1992, 15 adult dogs were presented to the Universities of Bristol, Glasgow, Liverpool and London with fractures of the radial carpal bone which had occurred without a known episode of violent trauma. Eleven of the dogs were boxers and the other breeds affected were a Pharaoh hound, rottweiler, springer spaniel and a greyhound. The condition was bilateral in three cases. Eleven dogs were treated surgically by cast immobilisation (four cases), fragment removal (one case), lag screw fixation (three cases), pan-carpal arthrodesis (one case) and lag screw reduction followed by pan-carpal arthrodesis (two cases). The remaining four dogs were treated conservatively with rest and tactical use of non-steroidal anti-inflammatory drugs. Follow-up periods ranged from two months to 11 years. Varying degrees of lameness, which tended to be exacerbated by exercise, persisted in all cases. The radial carpal bone appears to have at least three separate centres of ossification which eventually fuse; their planes of fusion correspond approximately to the two main fracture lines. These areas of fusion could be weak points within the radial carpal bone.     

Differentiation of dogs with regenerative and non-regenerative anaemia on the basis of their red cell distribution width and mean corpuscular volume

The red blood cell distribution width (RDW), which provides a quantitative measure of the heterogeneity of the red cell population (anisocytosis) in the peripheral blood, the mean corpuscular volume (MCV) and a regression model combining both variables were used to assess their predictive accuracy in differentiating 51 dogs with regenerative anaemia from 92 dogs with non-regenerative anaemia, which had been diagnosed on the basis of the corrected reticulocyte count A classification tree analysis was constructed to generate an optimum set of diagnostic rules to differentiate between the two types of anaemia. Seventy-four dogs with a normal haemogram were used as controls. An increase of 1 per cent in the RDW and of 1 fl in the MCV increased the odds of an anaemic dog suffering from regenerative anaemia by factors of 1.3 and 1.14, respectively. By the classification tree, 78 per cent of anaemic dogs with a RDW of 16.25 per cent or less would be expected to have non-regenerative anaemia. With a RDW over 16.25 per cent, an MCV of 68.2 fl was the cut-off between dogs expected to have regenerative (71 per cent) or non-regenerative (75 per cent) anaemia. The RDW and MCV are measured by most automatic haematology analysers and may give the first indication of the bone marrow response of an anaemic dog. However, different electronic counters give different normal values of the RDW and MCV.