Heritability estimates of tarsocrural osteochondrosis and palmar/plantar first phalanx osteochondral fragments in Standardbred trotters.

REASONS FOR PERFORMING STUDY: The pathogenesis of osteochondrosis (OC) and palmar/plantar first phalanx osteochondral fragments (POFs) is multifactorial, but specific knowledge of heritability is limited. OBJECTIVES: To improve the precision of heritability estimates and to estimate the genetic correlation between tarsocrural OC and POFs in Standardbred trotters. Further aims were to examine whether the prevalence of OC/POFs was different in the American and French lineages that have contributed to the Norwegian population, and if the prevalence was affected by heterozygosity. STUDY DESIGN: Retrospective cohort study. METHODS: Categorical data on tarsocrural OC and POFs from 2 radiographic studies performed in 1989 and 2007/2008 (n = 1217) were analysed with sire threshold models that included 230 sires. RESULTS: Heritability of OC at the distal intermediate ridge of the tibia and/or the lateral trochlear ridge of the talus was estimated at 0.29 ± 0.15. For OC at the distal intermediate ridge of the tibia only, the estimate was 0.40 ± 0.17. Heritability of POFs in all 4 limbs was estimated at 0.23 ± 0.13; for metatarsophalangeal POFs this was 0.26 ± 0.13 and for medial metatarsophalangeal POFs 0.32 ± 0.14. Estimates of genetic correlation between OC and POFs ranged from 0.68 ± 0.27 to 0.73 ± 0.28 but were not significantly different from a zero-genetic correlation. Effects of lineages or heterozygosity were not observed. CONCLUSIONS AND POTENTIAL RELEVANCE: This study confirmed a moderate to high heritability of tarsocrural OC and POF, providing further evidence of the heritable nature of these diseases. Examination of specific lesions yielded the highest heritability; therefore, breeding programmes and future genome-analysis studies should focus on predilection sites rather than the entire disease complex.

Views on euthanasia and the rehoming of dogs in Norway and Iceland.

According to several previously published studies, large populations of dogs are sent to animal shelters in the UK and USA each year, and estimates indicate that a substantial percentage of the dogs in such shelters are euthanased annually. However, anecdotal evidence indicates a different situation in Norway and Iceland. This study explores the attitudes toward euthanasia of dogs in Norway and Iceland, and investigates the practice of rehoming of dogs in the two countries. A general reluctance toward euthanasia of dogs was expressed, and participants stressed the need to consider alternatives such as rehoming. Rehoming of dogs was found to be negligible in Norway relative to international trends, and less than 10 per cent of the dogs assigned for rehoming were euthanased. In Iceland, the rehoming of dogs is yet to reach levels that necessitate the setting up of animal shelters. There is, nevertheless, reason to continue to explore the attitudes toward euthanasia and rehoming of dogs in Norway and Iceland, because there is a lack of statistical data on the reasons behind the owners' decisions to give away or euthanase their dogs.

Canine mammary gland tumours; a histological continuum from benign to malignant; clinical and histopathological evidence.

This study describes the clinical and histopathological findings in dogs with mammary gland tumours, and compares the histopathological and clinical evidence consistent with progression from benign to malignant to human breast cancer epidemiology. Clinical and histopathological data on 90 female dogs with 236 tumours was included. Dogs with malignant tumours were significantly older than dogs with benign tumours (9.5 versus 8.5 years), P = 0.009. Malignant tumours were significantly larger than benign tumours (4.7 versus 2.1 cm), P = 0.0002. Sixty-six percent had more than one tumour, and evidence of histological progression was noted with increasing tumour size. Dogs with malignant tumours were significantly more likely to develop new primary tumours than dogs with benign tumours, P = 0.015. These findings suggest that canine mammary tumours progress from benign to malignant; malignant tumours may be the end stage of a histological continuum with clinical and histopathological similarities to human breast carcinogenesis.

Changes in the relationships between dogs, owners and veterinarians in Norway and Iceland.

Norwegian and Icelandic dog owners were interviewed about aspects of their dog keeping and their attitudes to the veterinary profession. Dogs were found to play an important role in the lives of their owners, who had high expectations of their veterinarians, not only with respect to the treatment of their dogs but also with respect to themselves as clients. About one-third of owners reported problems related to a lack of trust and poor communications in encounters with their veterinarians.

Accessory ossification centres associated with osteochondral fragments in the extremities of horses.

Fifty-six tarsocrural joints and 94 metatarsophalangeal joints were examined, at necropsy, from horses aged < or = 2 years. Osteochondral fragments at the cranial aspect of the intermediate ridge of the distal part of the tibia were seen in six horses, and at the proximoplantar aspect of the proximal phalanx in seven horses. Defects in the proximoplantar aspect of the proximal phalanx without osteochondral fragments were seen in a further two horses. Inflammatory and degenerative changes were not observed in any of the joints examined. From the incidence and natural course of these fragments, and from the radiological and microscopical findings, accessory ossification centres would seem the most probable cause of the osteochondral fragments at the cranial aspect of the intermediate ridge of the distal part of the tibia and at the proximoplantar aspect of the proximal phalanx.

Porcine membranoproliferative glomerulonephritis type II: an autosomal recessive deficiency of factor H.

Hypocomplementaemic hereditary membranoproliferative glomerulonephritis (MPGN) type II is a common cause of the early loss of piglets in the Norwegian Yorkshire breed. The disease is associated with extensive complement activation due to a deficiency of factor H, a plasma protein which regulates complement. To investigate its mode of inheritance, 33 litters were bred from healthy animals associated with the disease, and a total of 385 recorded offspring were produced. The examination of renal tissue from the hypocomplementaemic piglets consistently revealed diagnostic signs of MPGN type II, including thickening of the glomerular capillary wall and proliferation of mesangial cells, dense intramembranous deposits, and massive glomerular deposits of complement component C3 and the terminal complement complex. No such glomerular lesions were detected in 20 normocomplementaemic littermates. The 88 affected piglets were present in 27 litters containing a total of 317 piglets, and there were approximately equal numbers of each sex. Retrospective immunoblot analysis and enzyme immunoassay of plasma samples from the MPGN-affected piglets and their healthy littermates revealed that the affected piglets were deficient in factor H, whereas the healthy piglets were not. It is concluded that porcine factor H deficiency is inherited as a simple autosomal recessive trait with complete penetrance, and consistently results in hypocomplementaemia and lethal membranoproliferative glomerulonephritis type II.

Markers of osteoarthritis: a review of the literature.

There may be a great potential in the use of diagnostic "markers" of osteoarthritis in synovial fluid to diagnose the disease in an earlier stage and perhaps assess the severity of the disease and monitor the effect of a treatment. In the present study, potential markers are characterized, discussed, and grouped according to the latest knowledge on the etiology, pathogenesis, and pathology of osteoarthritis. They are grouped according to their origin as either cartilage degradation products, or related to the mechanisms of cartilage degradation, or related to chrondrocytic anabolic activity during disease, or related to genetic disorders. Also potential markers that have not yet been studied clinically or experimentally are discussed. Examples of the progress that has been made in human medicine approaching reliable diagnostic markers that should also be tried in veterinary medicine are described.

Influence of radiographically detectable orthopedic changes on racing performance in standardbred trotters.

The tarsocrural, metacarpophalangeal, and metatarsophalangeal joints of 753 Standardbred yearlings were radiographed. On the basis of radiographic findings, the horses were allotted into 4 groups. Group-1 horses had osteochondrosis in the tarsocrural joints. Group-2 horses had palmar/plantar bony fragments in the metacarpo- and metatarsophalangeal joints. Group-3 horses had radiographic changes in the metacarpo- and metatarsophalangeal joint region, such as bony fragments located at the dorsoproximal end of the proximal phalanx, osteochondrosis of the sagittal ridge of the third metacarpus/metatarsus, ununited proximoplantar tuberosity of the proximal phalanx, or nonarticular, osteolytic and productive changes in the proximal sesamoid bones. Group-4 horses did not have radiographic changes. The number of race starts and race earnings (categorized) of the horses in groups 1, 2, and 3 were compared with those of the horses in group 4, using a multivariate regression analysis. Horses in groups 1, 2, and 3 had significantly fewer starts and somewhat lower earnings compared with the horses in group 4.

Progression and association with lameness and racing performance of radiographic changes in the proximal sesamoid bones of young standardbred trotters.

Radiographic examination of the metacarpo- and metatarsophalangeal joints was performed on 753 Standardbred trotters (6-21 months of age): 21 showed obvious changes in 26 proximal sesamoid bones on lateromedial projection. The radiographic changes were divided into 6 different types: (1) irregular abaxial margin (8 horses); (2) enlargement of the sesamoid bone (6 horses); (3) 'fracture' or separate centre of ossification of the apex (4 horses); (4) vertical, non-articular fracture of the plantar part of the sesamoid bone (1 horse); (5) a small bony fragment located in a defect in the apical part of the bone (2 horses); and (6) multiple areas of decreased radiodensity (1 horse). Each horse displayed only one type of radiographic change except for one which possessed those of types 3 and 5. Follow-up radiographic examination of 21 of the 26 affected proximal sesamoid bones at approximately 6-month intervals revealed a reduction in the changes in 13 bones and an unaltered condition in 8. Lameness examination was performed on 16 of the 21 horses at 3 years of age and 14 (87.5%) were observed to be lame, but detected lameness did not seem to be referrable to the sesamoid changes. Earnings after the racing season as 3- and 4-year-old horses showed no differences (P > 0.05) between horses with radiographic changes in the proximal sesamoid bones and those without such changes.

Heritability estimations of osteochondrosis in the tibiotarsal joint and of bony fragments in the palmar/plantar portion of the metacarpo- and metatarsophalangeal joints of horses.

Radiography of the tibiotarsal and metacarpo- and metatarsophalangeal joints was performed on 753 Standardbred trotters (6 to 21 months old) born in 1988. The surveyed population was drawn at random from all parts of Norway and represented about 60% of Standardbred trotters born the same year. Osteochondrosis in the tibiotarsal joint was diagnosed in 108 (14.3%) horses, and the prevalence of disease in progeny groups > 10 ranged from 0 to 69%. Bony fragments in the palmar/plantar portion of the metacarpo- and metatarsophalangeal joints were diagnosed in 89 (11.8%) horses, and the prevalence of disease in progeny groups > 10 ranged from 0 to 41%. Heritability analysis was restricted to 644 horses, comprising groups of 5 or more progeny, from 39 stallions. The heritabilities of osteochondrosis in the tibiotarsal joint and of bony fragments in the palmar/plantar portion of the metacarpo- and metatarsophalangeal joints were estimated to be 0.52 and 0.21, respectively, using a nonlinear model.