Genetic aspects of claw disorders,claw measurements and ‘type’ scores for feet in Friesian cattle

Data on claw measurements and disorders were collected on Black and White Friesian or Holstein heifers in 82 herds. Disorders were sole lesions and dermatitis interdigitalis and were determined on all heifers that had been milking between 40 and 100 days at the time of the visit. Heritabilities and genetic and phenotypic correlations among claw measurements and claw disorders were computed.Heritabilities for claw measurements were: angle, 0.25; length, 0.26; heel depth, 0.16; and heel depth-difference, 0.08. Angle and length estimated by eye had heritabilities of 0.18 and 0.22, respectively. The total of all lesion scores from different regions of the sole on both hooves had a heritability of 0.39. Heritabilities of dermatitis interdigitalis and sole ulcer (presence or absence) were 0.23 and 0.16, respectively.Claw measurements seemed to be more related to lesion scores than to dermatitis interdigitalis scores. Genetic correlations suggested that cows with higher claw angles had fewer dermatitis interdigitalis, total lesions and sole ulcers. Longer claws were genetically associated with higher total lesion scores and more sole ulcers. Claw measurements estimated by eye showed low genetic relations with claw disorders.Further research is needed to determine whether claw shape is a predisposing factor for or a result of a claw disorder.     

Does age of hot-blade trimming impact the performance and welfare of 2 strains of White Leghorn hens?

The impact of mild hot-blade beak trimming on welfare and performance in 2 strains of White Leghorn pullets was examined. During the pullet phase, 960 pullets were designated to one of 4 trimming treatments: control (untrimmed, C), trimmed at a commercial hatchery (T0d), or trimmed on farm at 10 d (T10d) or 35 d (T35d) of age. During the hen phase, 720 of the original 960 hens were housed in conventional cages at 17 wk of age (6 replications per strain × treatment group) and data were analyzed as a 2 × 4 (performance and beak length data), 2 × 2 (behavior data, blocked by observer) factorial arrangement or a Chi-Squared analysis (beak healing). Total hen-day production tended to be lower for C birds, but hen-housed production did not differ. Feed intake was not affected by trimming treatments, but feed efficiency was poorer for C birds. Treatment did not statistically affect mortality. Cannibalism, although not significantly different among treatments, occurred in C birds only. The C pullets displayed more head/vent pecking, but no differences were noted in adult birds. There was no behavioral or histological evidence of chronic pain or neuroma formation, and healing occurred quicker when trimming occurred at zero or 10 d of age. To conclude, trimming mildly at zero, 10, or 35 d of age caused no long-term effect on welfare or performance, but trimming at younger ages resulted in faster healing.     

Is there a lasting effect of functional claw-trimming on claw conditions?

The influence of regular claw-trimming on the occurrence and prevalence of claw disorders was examined on a total of 164 dairy cows (Simmental, Red Friesian, Holstein Friesian). Ten dairy farms in the Austrian province of Salzburg were used for this study. Three examinations of the claws were carried out with an interval of six months in between to find out claw disorders. The results were recorded according to a claw scoring system. The claw scores were in the range of other studies using the same scoring system. The median of the claw scores at the beginning of the study was 27 in the tied stall group compared with 37 in the loose housing group, remaining at that level in the first group and falling to 25 in the second group. All in all, the positive effect of regular claw trimming was more pronounced in the loose housing group than in the tethered housing group.     

Duty hours restriction for our surgical trainees: An ethical obligation or a bad idea?

To ensure patient safety and protect the well‐being of interns and residents, the Accreditation Council for Graduate Medical Education (ACGME) issued guidelines in 2003 limiting the working hours of physician trainees. Although many supported the goals of the ACGME, institutions struggled to restructure their programs and hire staff required by this unfunded mandate. Numerous studies have analyzed the effects of duty hours restrictions on patient outcomes and physician training over the past 15 years. Most agree that duty hours restrictions improved well‐being of house officers, but these improvements came at the expense of continuity, and patient hand‐offs led to medical errors. Effects on resident training are program specific, with duty hours restrictions having the most deleterious effects on surgical disciplines. Because veterinary specialists assume a similar role in providing 24‐hour patient care, interns and residents face work‐related stress as a result of extended working hours, on‐call duty, and an increasingly complex caseload. The North Carolina State Veterinary Hospital is staffed by approximately 100 house officers representing almost every veterinary specialty group. We surveyed departing house officers regarding their quality of life and training experience. Sixty‐six percent of interns and residents reported that they do not have time to take care of personal needs, and 57%‐62% felt neutral or dissatisfied with their mental and physical well‐being. Most trainees believed that decreased duty hours would improve learning, but 42% believed that decreased caseload would be detrimental to training. Veterinary educators must consider post‐DVM veterinary training guidelines that maintain patient care with a good learning environment for interns and residents.     

Dominance in domestic dogs—useful construct or bad habit?

The term “dominance” is widely used in the academic and popular literature on the behavior of domestic dogs, especially in the context of aggression. Although dominance is correctly a property of relationships, it has been erroneously used to describe a supposed trait of individual dogs, even though there is little evidence that such a trait exists. When used correctly to describe a relationship between 2 individuals, it tends to be misapplied as a motivation for social interactions, rather than simply a quality of that relationship. Hence, it is commonly suggested that a desire ‘to be dominant’ actually drives behavior, especially aggression, in the domestic dog. By contrast, many recent studies of wolf packs have questioned whether there is any direct correspondence between dominance within a relationship and agonistic behavior, and in contrast to wolves, hierarchical social structures have little relationship with reproductive behavior in feral dog packs. Nor do the exchanges of aggressive and submissive behavior in feral dogs, originally published by S. K. Pal and coworkers, fit the pattern predicted from wolf behavior, especially the submissive behavior observed between members of different packs. In the present study of a freely interacting group of neutered male domestic dogs, pairwise relationships were evident, but no overall hierarchy could be detected. Since there seems to be little empirical basis for wolf-type dominance hierarchies in dogs, the authors have examined alternative constructs. Parker's Resource Holding Potential (RHP) appears to be less useful when applied to domestic dogs than to other species, although it has the advantage of incorporating the concept of subjective resource value (V) as a factor influencing whether or not conflicts are escalated. The authors propose that associative learning, combined with V, can provide more parsimonious explanations for agonistic behavior in dogs than can the traditional concept of dominance.     

Is anthelmintic resistance a concern for heartworm control? What can we learn from the human filariasis control programs?

Heartworm prophylaxis is currently largely dependent on the ability of avermectins and milbemycins to arrest the development of third and fourth stages of Dirofilaria immitis for prolonged periods, without producing adulticidal effects. Major control programs, dependent on the activity of ivermectin, are being implemented for human onchocerciasis and lymphatic filariasis. The avermectins and milbemycins act on glutamate-gated and gamma-aminobutyrate-gated chloride channel subunit proteins in nematodes. Ivermectin resistance has been widely described in trichostrongylid nematodes of ruminants. There is evidence that when ivermectin resistance occurs in nematodes, there may be selection on some, but not all of the genes that code for ligand-gated chloride channel subunit proteins as well as on some ABC-transporter genes, whose products may be involved in regulating macrocyclic lactone drug concentrations at receptors, and on some structural protein genes of amphidial neurones. Although ivermectin resistance has not been reported in filarial nematodes, there have recently been reports of suboptimal responses to ivermectin in Onchocerca volvulus. Evidence has been found of ivermectin selection on at least ABC-transporter genes and some neuronal structural protein genes in O. volvulus. To date, there is no evidence of avermectin/milbemycin resistance in D. immitis, also a filarial nematode. Chemotherapy against trichostrongylids of animals, human filariae, and D. immitis, relies on avermectins or milbemycins. However, control involves targeting different stages or processes in the nematode life cycles, different control strategies, different proportions of the nematode population in refugia, and different drug dosage rates. Consideration of the proportion of the D. immitis population normally in refugia, the life cycle stage targeted, and the anthelmintic dosages used suggest that it is unlikely that significant avermectin/milbemycin resistance will be selected in D. immitis with current treatment strategies.     

Heterogeneity of ruminant pestiviruses: academic interest or important basis for the development of vaccines and diagnostics?

Pestiviruses cause economically important diseases of farm animals. Members of the Pestiviruses are bovine viral diarrhea virus 1 (BVDV-1), BVDV-2, classical swine fever virus (CSFV) and border disease virus (BDV). Phylogenetic analyses based on the entire nucleic acid sequence encoding the Npro allow a statistically significant segregation of established species and of subgroups within the species. BVDV-1 strains isolated in Germany can be associated with at least five different subgroups. In contrast all BVDV-2 isolates detected in Germany so far are closely related, belonging to one subgroup. A group of virus isolates from sheep and zoo animals is clearly different from established pestivirus species and can be designated as BDV-2. Antigenetic relatedness of pestiviruses was studied using defined virus isolates and antisera in cross-neutralization assays. Six antigenic groups were distinguished corresponding to the genetic clusters BVDV-1, BVDV-2, CSFV, BDV-1, BDV-2 and Giraffe-1. A significant antigenic difference was also observed between members of subgroups 1a and 1b of BVDV-1. Studies on the genetic and antigenic heterogeneity of pestiviruses are important for the development of new vaccines, diagnostic tests and for eradication programs.     

What can mathematical models bring to the control of equine influenza?

Mathematical modelling of infectious disease is increasingly regarded as an important tool in the development of disease prevention and control measures. This article brings together key findings from various modelling studies conducted over the past 10 years that are of relevance to those on the front line of the battle against equine influenza. The Summary is available in Chinese – see Supporting information.     

Research and implementation of novel approaches for the control of nematode parasites in Latin America and the Caribbean: is there sufficient incentive for a greater extension effort?

The widespread presence of anthelmintic resistant gastrointestinal parasitic nematodes in outdoor ruminant production systems has driven the need to identify and develop novel approaches for the control of helminths with the intention to reduce the dependence on commercial anthelmintic drugs. This paper identifies what has been done in Latin America (LA) in terms of estimating the prevalence of anthelmintic resistance (AR) in ruminant production systems and the application of different novel approaches for the control of helminths in those systems, including research and extension activities. Firstly, the paucity of knowledge of AR is discussed in the context of different countries, as well as, the available economic resources for research, the technical infrastructure available and the practical difficulties of the production systems. It is then proposed that the search for novel approaches is not only driven by AR but also by the need for techniques that are feasible for application by resource-poor farmers in non-commercial subsistence farming systems. However, the commercial benefits of these approaches are often limited and so are funding inputs in most countries. The workers participating in the research into different novel approaches are identified as well as the different methods being studied in the different areas of LA according to their published results. In addition, the difficulties experienced during extension efforts to reach farmers and help them to adopt novel approaches for the control of parasitic nematodes in LA are discussed. The role of regulatory authorities in these countries is discussed as some methods of control might need an official confirmation of their efficacy as well as authorization prior to application as they may affect animal products (i.e. residues) and/or impose a hazard for animal welfare. The role of the pharmaceutical companies is also discussed.     

Is moisture really the most important influencing factor on the mechanical properties of claw horn? Modulus of elasticity and dry-matter content in flat and contracted claws

The modulus of elasticity (E) and dry matter content (DMC) of horn samples from two types of claw deformity (contracted and flat claws) were determined according to EN-ISO 527 and ASTM D 638-03. The overall E values for all segments combined were 168 +/- 154 MPa (mean +/- SD, n = 79) and 248 +/- 196 (n = 90) for contracted and flat claws, respectively. These values were approximately 60% and 40% less than the E value of sound claw material.The high correlation between E and DMC, as previously found for sound claw horn material was not present in horn obtained from these types of pathologically altered claws.     

Breeding or assisted reproduction? Relevance of the horse model applied to the conservation of endangered equids

Many wild equids are at present endangered in the wild. Concurrently, increased mechanization has pushed back the numbers of some old native horse breeds to levels that are no longer compatible with survival of the breed. Strong concerns arose in the last decade to preserve animal biodiversity, including that of rare horse breeds. Genome Resource Banking refers to the cryostorage of genetic material and is an approach for ex situ conservation, which should be applied in combination with in situ conservation programmes. In this review, we propose that, owing to the great reproductive similarity among the different members of the genus Equus, the domestic horse can be used to optimize cryopreservation and embryo production protocols for future application in wild equids. We will give this hypothesis a scientific underpinning by listing successful applications of epididymal sperm freezing, embryo freezing, intracytoplasmic sperm injection, oocyte vitrification and somatic cell nuclear transfer in domestic horses. Some ART fertilization methods may be performed with semen of very low quality or with oocytes obtained after the death of the mare.     

Heck cattle in the Oostvaardersplassen: risk for infectious diseases or not?

This article discusses risk analysis of infectious diseases in a cattle population. Heck cattle living in nature reserve 'De Oostvaardersplassen' were studied as an example of the risk analysis approach. Twenty-five adult cattle were tested for every infectious disease agent that the risk analysis indicated might be prevalent. All sampled cattle tested positive for Bovine Herpesvirus 1, whereas the prevalence of antibodies against other infectious disease agents was below the level that was assumed to be the threshold for spread of the disease to cattle in the surrounding areas. Risk management of infectious diseases was expressed in a so-called 'low-risk profile'. The risk of introduction or spread of infectious diseases was estimated to be very low as long as the population was kept strictly enclosed.