Congenital spinal stenosis in beef calves in western Canada

Nineteen calves with a clinical history of posterior weakness or ataxia were examined at necropsy. Dorsoventral narrowing of the vertebral canal and myelopathy were found in the thoracic and lumbar areas of the spinal cord; vertebral metaphyseal growth plates had focal areas of premature closure. Malformation of the cranial base and hydrocephalus were also observed. Shortening of long bones and malformation of long bone epiphyses were prominent findings and were associated with focal premature closure of metaphyseal growth plates. The cause of these lesions is unknown; possible causes, including a maternal deficiency of manganese, are discussed.     

Lethal osteogenesis imperfecta and skin fragility in newborn New Zealand Romney lambs

Osteogenesis imperfecta and skin fragility occurred in about 50 New Zealand Romney lambs born in a flock of 450 ewes. Affected lambs had soft bones and multiple intrauterine bone fractures. Long bones had a thickened diaphysis with almost complete absence of a medullary cavity. Other consistent gross findings were moderate brachynathia inferior, subcutaneous oedema, marked joint laxity, dark blue sclera and small pink teeth. Histopathologic and ultrastructural changes were consistent with a defect in collagen production by fibroblasts. DNA finger-printing was used to identify which of the five rams used in the flock was carrying the genetic defect. The disease was inherited as an autosomal dominant trait and was considered to be a new mutation in the testicular germ cell lines of this ram.     

Iatrogenic fractures of ribs and vertebrae during delivery in perinatally dying calves: 235 cases (1978-1988)

To determine the pathogenesis of vertebral fractures in calves during the perinatal period, a retrospective study was done to determine the relationships between clinical factors at dystocia and the findings during necropsy of 235 perinatally dying calves. It was concluded that excessive traction is the most important cause of rib and vertebral fractures in the calf during dystocia. Vertebral fractures in perinatally dying calves may not be simply judged as a sign of asphyxia. The occurrence of vertebral fractures is highly correlated with the type of delivery and the force of traction. The veterinarian as well as the type of calf also are influencing factors. More perinatally dying calves were delivered after hips were locked, when extraction had been forced, or through induction of trauma when the head of the calf had the pelvic canal during the first obstetric examination. Consequently, fetal position at delivery may predispose calves to risky extractions and to the risk of perinatal death secondary to trauma. In light calves, significantly more vertebral fractures occurred during extractions than in other calves. Therefore, the veterinarian should accurately estimate the birth weight of the calf and the force of traction that should be applied.     

Osteogenesis imperfecta in two litters of dachshunds

A clinical, morphologic, ultrastructural, and genetic study was performed on five rough-coated dachshund semisiblings with osteogenesis imperfecta (OI). Clinical signs consisted of pain, spontaneous bone and teeth fractures, joint hyperlaxity, and reduced bone density on radiography. Primary teeth were extremely thin-walled and brittle. The hallmark of the disease was a severe osteopenia characterized by impairment of lamellar bone formation in the long bones, skull, and vertebral column. No deformity or dwarfism was present. The columns of chondrocytes and primary trabeculae in the epiphyses and metaphyses were histologically normal. An abrupt failure of secondary spongiosa and lamellar bone formation was evident in the medullary and cortical zones in all animals. The few existing trabeculae consisted of woven bone. There was no increase in the number and size of osteoclasts or lacunae. In the teeth, the dentine layers were thin and lacked a tubular pattern. Ultrastructurally, osteoid apposition on bone surfaces was reduced, and small numbers of large cytoplasmic vacuoles were present in a few osteoblasts. Molecular analyses of the collagen type I-encoding genes COL1A1 and COL1A2 revealed several nucleotide differences compared with the published canine sequences but were not significant for OI. Therefore, OI in these Dachshund litters was characterized by a severe, generalized osteopenia and dentinopenia. This pattern of reduced bone formation is suggestive of defective production of collagen type I.     

Suspect osteogenesis imperfecta in a male kitten

A 4.5-month-old, male domestic shorthair was presented with bilateral femoral fractures after falling from a low height. Radiographs revealed reduced radio-opacity and thin cortices of all long bones. A presumptive diagnosis of osteodystrophy, secondary to osteogenesis imperfecta, was made on postmortem examination.     

Skeletal changes in hemochromatosis of Salers cattle

Hemochromatosis is an inherited defect in Salers cattle, characterized by increased iron absorption and wasting in young animals. Loss of teeth and soft bones has been reported. This study details bone changes in a prospective study of an affected Salers heifer and an age-matched, half-sibling control. The heifer fell 2 weeks before euthanasia, developed non-weight bearing lameness, and then became recumbent. At necropsy, the heifer was smaller than the control and had fractures of the humerus, femur, and ribs. Distinctive circumferential laminations in the outer third of the cortex were seen radiographically as layers of variably decreased density. In midshaft cross sections, the cortex was wider in some long bones, and fluorescent labeling revealed irregular and intermittent mineralization in the outer cortical layers. Mineral apposition rates in osteons of the inner cortex were decreased as compared with the control, and longitudinal bone formation at the growth plate was markedly decreased. Histologically, there were buried layers of osteopenic, poorly mineralized plexiform bone in outer circumferential lamellae. There was stainable iron in woven bone cores of the matrix. Iron was found in occasional osteoclasts as well. The mandible was severely affected, with loss of cortical bone as well as trabecular bone around the teeth and resorption of dental roots. Bone analysis revealed iron levels in the affected calf that were 30-50 times greater than the control and decreased percent ash in the outer cortex. These results indicate that periosteal dysplasia and osteopenia are responsible for pathologic fractures and tooth loss.     

A retrospective study of dystocia-related vertebral fractures in neonatal calves

Forty-seven cases of neonatal vertebral fractures/luxations occurred in a 21 year period (1967-1987). All of the fractures were located between the 11th thoracic vertebra and the fourth lumbar vertebra; 77% occurred at the thoracolumbar junction. All but one case was associated with a forced extraction, either unspecified (53%), mechanical (28%), or manual (17%).

A weak calf or continuous recumbency since birth was the major clinical sign. Hemorrhage around the kidneys, adrenal glands, and in perivertebral muscles was a consistent necropsy finding and a useful indicator that a thoracolumbar fracture was present. In addition to the vertebral fracture, the prominent necropsy findings were subdural and epidural hemorrhage, myelomalacia, spinal cord compression or severed spinal cord, and fractured ribs. All of the calves died or were euthanized without regaining locomotory function.

     

High-intensity exercise of short duration alters bovine bone density and shape

The ability of short-duration high-intensity exercise to stimulate bone formation in confinement was investigated using immature Holstein bull calves as a model. Eighteen bull calves, 8 wk of age, were assigned to one of three treatment groups: 1) group-housed (GR, which served as a control), 2) confined with no exercise (CF), or 3) confined with exercise (EX). The exercise protocol consisted of running 50 m on a concrete surface once daily, 5 d/wk. Confined calves remained stalled for the 42-d duration of the trial. Blood samples were taken to analyze concentrations of osteocalcin and deoxypyridinoline, markers of bone formation and resorption. At the completion of the trial, calves were humanely killed, and both forelegs were collected. The fused third and fourth metacarpal bone was scanned using computed tomography for determination of cross-sectional geometry and bone mineral density. Three-point bending tests to failure were performed on metacarpal bones. The exercise protocol resulted in the formation of a rounder bone in EX as well as in increased dorsal cortex thickness compared with those in the GR and CF. The exercised calves had a significantly smaller medullary cavity than CF and GR (P < 0.01) and a larger percentage of cortical bone area than CF (P < 0.01). Dorsal, palmar, and total bone mineral density was greater in EX than in CF (P < 0.05), and palmar and total bone mineral densities were greater (P < 0.05) in EX than in GR. There was a trend for the bones of EX to have a higher fracture force than CF (P < 0.10). Osteocalcin concentrations normalized from d 0 were higher in EX than CF (P < 0.05). Therefore, the exercise protocol altered bone shape and seemed to increase bone formation comparison with the stalled and group-housed calves.     

Performance, survival, necropsy, and virological findings from calves persistently infected with the bovine viral diarrhea virus originating from a single Saskatchewan beef herd.

Fifty-one calves from 652 cows and heifers that calved on a Saskatchewan ranch in 1992 were identified as persistently infected with bovine viral diarrhea virus (BVDV), based on virological and necropsy findings. Herd records suggested a further 20 calves that died between birth and weaning were probably also persistently infected. Subsequent to weaning, all surviving persistently infected calves were transferred to one pen in a 10,000 head commercial feedlot, to mimic normal management practice in western Canadian beef herds. On average, when compared with healthy, BVDV-negative herdmates, persistently infected calves were "poor doers" and had poor survivability, with only 4 persistently infected calves surviving to 1 year of age. There was no difference (P > 0.05) in survival between male and female persistently infected calves. The clinical, pathological, and virological findings from these persistently infected calves varied over time. The majority of persistently infected calves had gross pathological lesions at necropsy, consistent with mucosal disease. However, approximately 25% of the persistently infected calves had gross pneumonic lesions at necropsy, with no or only mild lesions of mucosal disease. A wide variety of other lesions were also noted in persistently infected calves at necropsy. Therefore, the possibility that BVDV-induced lesions can be misdiagnosed is very real. The results of this study indicate that persistent infection with BVDV should always be considered in calves with chronic ill thrift, chronic enteritis, or respiratory disease.     

Femoral fractures in the newborn calf: biomechanics and etiological considerations for practitioners.

The etiology of femoral fractures in calves during assisted parturition was examined from the perspective of biomechanical force analysis. Femurs were collected from newborn calf cadavers. Their physical dimensions of length, cortical thickness, and diameter were measured from radiographs, and the data were recorded. The bones were then frozen until tested. The thawed bones were compressed axially in a materials testing machine until they broke, whereupon the breaking strength of the bones at the failure site was recorded. Fracture locations were documented radiographically, and the cortical thickness and bone diameter at the fracture site were determined. Fracture configurations and locations were similar to those found in clinical cases associated with forced extraction. The breaking strength of all femurs fell within the magnitude of forces calculated to be created when mechanical devices are used to assist delivery during dystocia. An etiology based on wedging of the femur in the maternal pelvis and resulting compression during forced extraction is suggested to account for the occurrence of supracondylar fractures of the femur of calves delivered in anterior presentation using mechanical devices in a manner commonly performed by veterinarians and owners. It is recommended that care should be exercised to correct or rule out the possibility of premature engagement of the calf's stifle into the birth canal, and thereby reduce the frequency of this type of fracture occurrence in the field.     

Metacarpal and metatarsal fractures in dogs

Metacarpal fractures were more common than metatarsal fractures in this retrospective study of 37 dogs. Fractures of one metacarpal or metatarsal bone occurred In 24 per cent of the dogs, two metacarpal bones in 16 per cent, three metacarpal or metatarsal bones in 19 per cent, and four metacarpal or metatarsal bones in 41 per cent. Eighty-seven per cent of the dogs with fractures of four bones had fracture displacement or malalignment of at least one digit. Progressive fracture healing usually occurred Irrespective of stabilisation method. For malaligned fractures, however, external coaptation did not consistently improve alignment. Fracture alignment was consistently Improved by open reduction and internal fixation of acute fractures with bone plates. Fractures of four bones occurred most often In the distal metacarpus as opposed to the proximal metatarsus. Therefore, open reduction and internal fixation may be more commonly indicated for severe metacarpal fractures, because fracture displacement or axial1 malalignment was significantly associated with fractures of the mid or distal regions of the metacarpus or metatarsus (P=0.052).     

Bone fragility in a kitten: an osteogenesis imperfecta-like syndrome

A 12-year-old kitten was found to have bone fragility. Previously described causes of bone fragility in domestic cats were excluded on the basis of serum biochemical profile and radiographic histologic examinations. The findings in this kitten correlated most closely with osteogenesis imperfecta, a syndrome documented in human beings and cattle.     

Growth and sexual characteristics of suckling beef calves as influenced by age at castration and growth implants

A 2-yr study using crossbred male calves (n = 228) evaluated castrating at birth or at 4 mo of age and use of anabolic growth implants (none, zeranol or estradiol-17 beta). Angus, Hereford and Brahman crossbred calves produced in seven cow-calf units that varied by breed component, stocking rate and calving season were allotted to treatment at birth in a 2 x 3 factorial arrangement. Growth implants decreased (P less than .01) testicular weight and expression (P less than .05) of male secondary sex characteristics in suckling bull calves at 4 mo. Implanted calves were shorter (P less than .05) at the hips and had shorter front legs (P less than .01) at both 4 mo and at weaning. Cannon bone circumference at weaning was increased (P less than .05) by growth implants. Age at castration did not affect (P greater than .05) calf performance or body characteristics. Calves given growth implants had higher (P less than .05) rates of gain from birth to 4 mo than did nonimplanted calves (.75 vs .71 kg/d). Implanted calves were heavier (P less than .01) at weaning and had higher (P less than .01) ADG from 4 mo to weaning than did nonimplanted calves. These data indicate no benefit from delaying age at castration, but implanting increased weaning weight an average of 8.2 kg.     

Effects of Tuli,Senepol, Brahman,Angus, and Polled Hereford Sire Breeds on Birth and Weaning Traits of Offspring

Progeny (n = 861) of tropically adapted breeds [Tuli (TU), Senepol (SE), and Brahman (BR)] and temperate breeds [Angus (AN) and Polled Hereford (HP)] were evaluated for birth and weaning traits in each of 5 yr. Multiparous crossbred cows representing three genetic types [British (Bt), ½BR½Bt, and ¾Bt¼BR] were mated to AN, HP, TU, SE, and BR sires, with the exception that BR sires were not mated to ½BR½Bt cows. Calving season was January through early March. Following calving, cows were provided bermudagrass hay and bahiagrass hay and had limited access to rye and ryegrass pastures. Cow and calf pairs grazed bermudagrass and bahiagrass pastures as available until weaning without access to creep feed. Male calves were castrated at birth and were not implanted. Data included birth weight, cannon bone length at birth, weaning weight, weaning hip height, ADG from birth to weaning (ADGBW), ADG from birth to April (ADGBA), ADG from April to weaning (ADGAW), and weight per day of age (WDA). Data were analyzed by PROC Mixed using a model that included calf genetic type, calf sex, calf birth day of year, and calf genetic type × calf sex interaction. Random effects were cow age, birth year, and sire and dam of calf. Calf genetic type and calf sex were significant sources of variation for all characteristics. Linear contrasts revealed that BR-sired calves were heavier at birth, had longer cannon bones at birth, and were taller at weaning (P<0.01). Tuli- and SE-sired calves were similar to AN- and HP-sired calves for birth weight, cannon bone length at birth, and weaning hip height. Angus-, HP-, and BR-sired calves were heavier at weaning compared with TU-sired calves, and SE-sired calves were intermediate for weaning weight (P<0.01). In conclusion, the TU-sired calves were smaller at birth and at weaning when compared with BR-sired calves. The TU- and SE-sired calves appear to offer more moderate size and growth rate through weaning than do the BR-sired calves.     

Medullary bone of piglets.

The bone marrow is commonly present in the medullary cavity of long bones in most mammals at birth. In the present study, the persistence of the osseous tissue was examined in the medullary cavities of piglet bones at and after birth. Immediately after birth, medullary cavities of long bones were almost completely filled with the spongy bone. The persisted spongy bone, i.e., medullary bone was prominent in younger pigs but decreased with advance in age. By 90 days of age, the medullary bone almost disappeared to form the extended medullary cavity. During the disappearing process of the medullary bone, osteoclasts showed significant increase in size and number (p less than 0.05). In irregular and flat bones, osseous trabeculae of the medullary bone became slender with age. The extramedullary hematopoiesis in the liver and spleen was very active till 30 days of age. This may suggest that the persistence of the medullary bone narrows the medullary cavity to cause poor medullary hematopoiesis and is compensated by extramedullary hematopoiesis. The relationship among the medullary bone, extramedullary hematopoiesis and piglet anemia was discussed.     

Hereditary neuraxial oedema in a Poll Hereford herd

Cases of neuraxial oedema in a Poll Hereford herd were investigated and the pedigrees of affected calves determined. In all cases, and over no more than 3 generations, the pedigree led back to a common bull. Analysis of the herd breeding records supported an autosomal recessive mode of inheritance of the disease. Fractures of the femoral heads, acetabular cartilage and/ or bone, or both, were seen in some affected calves. This lesion was probably induced during birth or soon after, and the suggestion is made that such hip lesions could be regarded as highly suggestive of hereditary neuraxial oedmea of Herefords. The majority of calves showed clinical signs at birth, but 2 calves did not develop clinical signs until they were 2 days old.     

The use of a circular external skeletal fixation device for the management of long bone osteotomies in large ruminants: an experimental study

The study was undertaken to evaluate the feasibility of a simple, inexpensive model of circular external fixator (CEF) for use in large ruminants. A simple model of CEF frames consisting of four full rings (13-19 cm diameter, 4 cm wide and 4 mm thick with 18-24 holes) connected by threaded rods (8 mm diameter, 10-15 cm long) and nuts was developed using mild (low carbon) steel and were nickel-plated. In the first phase of the study, three male cow calves were utilized to study the feasibility of application of the fixators in the metatarsus, tibia and radius, in reference of adaptation and tolerance by animals. In the second phase, the fixators were tested in osteotomized bones. Six bull calves of 1.5-2 years of age weighing about 200-250 kg were utilized for this purpose. After preparing the area for aseptic surgery, under xylazine (at 0.1 mg/kg, i.m.)-ketamine (i.v. till effect) general anaesthesia, the test bone (metatarsus, radius and tibia in two animals each) was approached through the medial surface and an osteotomy was created with a saw and chisel at the mid-diaphysis. The pre-constructed 4-ring CEF was mounted on the limb around the test bone in such a way that it formed a cylinder with the axis of the limb at the centre. Each ring was then fixed to the bone with a pair of beaded wires (316 SS) of 3.5 mm diameter. During the post-operative period, the animals were observed for any change in behaviour, tolerance of the fixators, the weight bearing on the test limb, the status of the fixator, and the level of reduction of the osteotomy, alignment and healing at different intervals. The fixation of CEF was easier in the metatarsus and radius than in the tibia. The inner ring diameters found adequate for metatarsus, radius and tibia were 13-15 cm, 15-17 cm and 17-19 cm, respectively. The fixators applied to different bones were well-tolerated, and the animals could lay down, stand and walk freely with the fixator without any problems. All the animals showed good weight bearing in the immediate post-operative period. Weight bearing, however, slightly reduced in the inflammatory period and showed improvement after about 4 weeks. Wire tract infection was seen in all the animals, which was more on proximal wire tracts on lateral aspect of limbs. Circular fixators were well-tolerated by all the animals, and there was no breaking/bending of connecting rods, slotted bolts or the rings at any stage of observation. Slight bowing of some wires was noticed in cases of tibia and radius (in phase II) and bending of some wires was noticed from first week in two animals one each in radius and tibia. Bone fragments were well maintained until healing occurred (appearance of bridging periosteal callus) at 60-70 days. The functional results were good in all but one case of tibia, where a mal-union was recorded. From this study, it can be concluded that CEF are well-tolerated by large ruminants and can be used to treat long bone fractures. The fixator assembly using mild steel is sufficiently strong to maintain fracture fixation and is inexpensive. The simple design of the CEF appears to be sufficient to treat simple diaphyseal fractures of the metatarsus and radius. Improvement in the technique of fixation and design-like coupling of linear and circular fixator components into hybrid constructs may help to provide greater rigidity in treating tibial and open long bone fractures.     

Investigations on the Occurrence of Hereditary Diseases in the Danish Cattle Population 1989-1991

Agerholm, J.S., A. Basse and K. Christensen: Investigations on the occurrence of hereditary diseases in the Danish cattle population 1989-1991. Acta vet. scand. 1993, 34, 245-253.– The methods of the Danish Bovine Genetic Disease Programme are outlined, and the results obtained during the first 3 years in function are described. The most common disease reported was spinal muscular atrophy in calves of the Red Danish Dairy breed with 312 reports. Necropsy was performed on 162 cases, and spinal muscular atrophy was diagnosed in 82 of these. Bovine progressive degenerative mye-loencephalopathy, rectovaginal constriction, syndrome of arthrogryposis and palatoschisis, hereditary chondrodysplasia (2 different types), syndactylism, epitheliogenesis imperfecta, and osteogenesis imperfecta was diagnosed with 1 case each. Lethal trait A46 was diagnosed in 4 calves. Some of these diseases have not previously been described in Denmark, and epitheliogenesis imperfecta was for the first time diagnosed in the Hereford breed. Chromosome translocation 1/29 was detected in the Blonde d’Aquitaine (BAQ), Limousine, and Red Danish Dairy breed. The aberration occurred frequently in BAQ. Furthermore, a complex chromosome translocation t(l;8;9)(q45;ql3;q26) was detected in the Red Danish Dairy breed.     

Skeletal lesions of canine hepatozoonosis caused by Hepatozoon americanum

Canine hepatozoonosis, caused by Hepatozoon americanum, is an emerging tick-borne disease of dogs in North America. In addition to the skeletal and cardiac myositis that are prominent features of the disease, there is disseminated periosteal bone proliferation in most dogs that manifest clinical disease. Each of six experimentally infected animals (four dogs and two coyotes) and seven of eight naturally infected dogs had gross or histopathologic osteoproliferative lesions. Experimental animals were 6-9 months of age when exposed. Naturally infected dogs were 8 months to 11 years old when subjected to necropsy. Lesions occurred primarily on the diaphysis of the more proximal long bones of the limbs; however, flat and irregular bones were frequently involved. Lesions involving metacarpals, metatarsals, and digits were infrequent. The earliest observed periosteal lesions were in an experimentally infected dog 32 days after exposure to sporulated oocysts of H. americanum. There were hypertrophy and hyperplasia of osteoprogenitor cells, and osteoblasts appeared in the cellular zone of the periosteum. Spicules of woven bone oriented perpendicularly to bone cortex followed. Later yet, periosteal new bone was remodeled and tended to become oriented parallel to the cortical bone. Horizontally oriented zones of remodeled, condensed bone sometimes occurred in multiple layers on the original cortex, forming "pseudocortices." The osseous lesions of American canine hepatozoonosis, with few variations, are remarkably similar to those of hypertrophic osteopathy in domestic dogs and other mammalian species, including humans.     

The physiological and physical status of single calves at birth in a dairy herd in New Zealand

AIM: To determine the physiological status of calves at birth and the perinatal factors that might predispose newborn calves to debility and death, using criteria previously established for newborn lambs. METHODS: Friesian mixed-aged cows and heifers on a dairy farm in New Zealand that were close to calving were separated from the main herd and observed 24 h a day until they calved. Cows in which labour did not progress for over 1 h or which were in distress were assisted. About 12-13 min after birth, rectal temperature was measured and a blood sample was taken from each calf. The packed cell volume (PCV) and plasma lactate, glucose and fructose concentrations were determined. The time to stand for each calf and the air temperature and weather conditions at birth were recorded. RESULTS: The parameters measured were within normal ranges for newborns for the majority of calves. Calves sired by an Angus bull and born to heifers (AngusX) had significantly higher plasma lactate and fructose concentrations than Friesian calves born to cows, but there were no significant differences between the two breeds in any of the other parameters measured. Calves of both breeds born with assistance had significantly higher plasma lactate concentrations than those born without. Friesian calves that were assisted at birth had significantly lower PCVs and took significantly longer to stand than calves born without assistance. Assisted AngusX calves were significantly heavier than their unassisted counterparts. Calves born during windy and wet weather and when air temperatures were below 10 degrees C had lower rectal temperatures, took longer to stand and had higher plasma glucose concentrations than those born in dry weather and when air temperatures were above 10 degrees C. CONCLUSIONS: Calves with physiological parameters outside the normal range had experienced difficult labour and/or intrapartum hypoxaemia. Placental insufficiency and maternal undernutrition during late pregnancy did not apparently contribute to neonatal problems in the present study.