Oral malignant melanomas and other head and neck neoplasms in Danish dogs - data from the Danish Veterinary Cancer Registry

Background

Head and neck cancers (HNC) are relatively common and often very serious diseases in both dogs and humans. Neoplasms originating in the head and neck region are a heterogeneous group. HNC often has an unfavourable prognosis and the proximity of the tissue structures renders extirpation of tumours with sufficient margins almost incompatible with preservation of functionality. In humans oral malignant melanoma (OMM) is extremely rare, but represents a particular challenge since it is highly aggressive as is the canine counterpart, which thus may be of interest as a spontaneous animal model.

Methods

Canine cases entered in the Danish Veterinary Cancer Registry (DVCR) from May 15th 2005 through February 29th 2008 were included in this study. Fisher''s exact test was used to compare proportions of HNC in dogs and humans as well as proportions of surgically treated cases of OMM and squamous cell carcinomas (SCC). Also the proportions of benign and malignant neoplasms of different locations in dogs were compared using Fisher''s exact test.

Results

A total of 1768 cases of neoplasias (679 malignant, 826 benign, 263 unknown) were submitted. Of all neoplasias HNC accounted for 7.2% (n = 128). Of these, 64 (50%) were malignant and 44 (34%) benign. The most common types of malignant neoplasia were SCC (18; 28% of malignant), OMM (13; 20% of malignant), soft tissue sarcoma (11; 17% of malignant) and adenocarcinoma (5; 11% of malignant). The most common types of benign neoplasms were adenoma (7; 16% of benign), polyps (6; 14% of benign) and fibroma (5; 11% of benign).

Conclusions

In the current study, the proportion of neoplasia in the head and neck region in dogs in Denmark was similar to other canine studies and significantly more common than in humans with a large proportion of malignancies. Spontaneous HNC in dogs thus, may serve as a model for HNC in humans.Canine OMM is a spontaneous cancer in an outbred, immune-competent large mammal population and could be a clinical model for OMM in humans.     

Changes in platelet function in Dachshunds with early stages of myxomatous mitral valve disease

The aim of this study was to evaluate platelet function in Dachshunds during early stages of myxomatous mitral valve disease.Clinical examination and echocardiography were performed in 34 wirehaired standard sized Dachshunds. Platelet function was evaluated using the PFA-100 (reported as closure time). In addition, whole blood platelet aggregation response and hemostatic markers were evaluated.Significant longer PFA-100 closure time (CT) was found in 12 Dachshunds with mild mitral regurgitation (MR) compared to 22 Dachshunds with minimal MR. Only five Dachshunds responded to adenosine diphosphate in the whole blood aggregation analyses. There were no differences between the two dog groups in plasma fibrinogen, plasma von Willebrand factor (vWf) or vWf multimer distribution; however, there was a significant correlation between CT and plasma vWf concentration and CT and plasma fibrinogen concentration.The higher CT found in Dachshunds with mild MR suggests a form of platelet dysfunction in Dachshunds with MR.     

Tissue factor activated thromboelastography correlates to clinical signs of bleeding in dogs

The ability of a laboratory assay to correlate to clinical phenotype is crucial for the accurate diagnosis and monitoring of haemostasis and is therefore challenging with currently used routine haemostasis assays. Thromboelastography (TEG) is increasingly used to evaluate haemostasis in humans and may well be of value in the workup of dogs suspected of having a haemostatic disorder. This study was undertaken to evaluate prospectively how tissue factor (TF) activated TEG correlated to clinical signs of bleeding in dogs, compared to a routine coagulation profile. A prospective case-control study was performed over a 2 year period from 2004-2006. Eligible dogs were those where the primary clinician requested a coagulation profile to evaluate haemostasis. The dogs were simultaneously evaluated with a TF-activated TEG assay. Twenty-seven dogs, characterised as hypo-coagulable based on the TEG parameter G (<3.2 Kdyn/cm(2)), were included in the study as cases. Size matched control groups of TEG normo- (G=3.2K-7.2 Kdyn/cm(2)) and hyper-coagulable (G>7.2 Kdyn/cm(2)) dogs were selected retrospectively from the eligible dogs. For all dogs, clinical signs of bleeding were noted at time of analysis. There were statistically significant differences between all TEG values of hypo- and normo- and hyper-coagulable dogs. Thromboelastography correctly identified dogs with clinical signs of bleeding with a positive predictive value (PPV) of 89% and a negative predictive value (NPV) of 98% based on G alone. In comparison, the coagulation profile had a PPV between 50-81% and a NPV between 92-93% for detection of bleeding, depending on the observer. In conclusion, a TF-activated TEG G value<3.2K dyn/cm(2) correctly identified dogs with clinical signs of bleeding with very high PPV and NPV, irrespective of observer. The findings strongly suggest that TF- activated TEG may be of value in the workup of dogs suspected of having a haemostatic disorder.     

Does oxidation affect the water functionality of myofibrillar proteins?

Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with and without exposure to H2O2, were characterized using low-field proton NMR T2 relaxometry. The effects of pH and ionic strength in the samples were investigated as pH was adjusted to 5.4, 6.2, and 7.0 and ionic strength was adjusted to 0.29, 0.46, and 0.71 M, respectively. The formation of dityrosine as a measure of oxidative protein cross-linking revealed a significant increase in dityrosine concentrations upon H2O2 activation. The formation of dityrosine was strongly pH-dependent and increased with decreasing pH. In addition, increased levels of thiobarbituric acid reactive substances were observed upon addition of H2O2, implying that lipid oxidation was enhanced, however, with a different oxidation pattern as compared to the myofibrillar proteins. Low-field NMR relaxation measurements revealed reduced T2 relaxation times upon H2O2 activation, which corresponds to reduced water-holding capacity upon oxidation. However, a direct relationship between degree of oxidation and T2 relaxation time was not observed with various pH values and ionic strengths, and further studies are needed for a complete understanding of the effect of oxidation on myofibrillar functionality.     

Linking forest history and conservation efforts: Long-term impact of low-intensity timber harvest on forest structure and wood-inhabiting fungi in northern Sweden

Throughout the northern hemisphere old forests with high abundance of dead wood are rare features in most landscapes today, and the loss of dead wood constitutes a serious threat to the existence of many species. This study, using field surveys and dendrochronology, examines the relationship between wood-inhabiting fungi and past forest utilisation along a gradient of early logging activity. Data were collected in three late-successional Scots pine forests in northern Sweden. Nonmetric Multidimensional Scaling (NMS) was then used to assess differences in species composition among the forests. Our results show that minor forest logging (22-26 cut stumps ha⁻¹) carried out a century ago may have continuing effects on forest characteristics, including dead wood dynamics and the wood-inhabiting fungal community - especially the abundance of red-listed species. The most important effects are lower numbers of logs in early and intermediate stages of decomposition. Additionally, numbers of species (including red-listed species) can be high in forests that have been subject to low levels of logging. Overall, the high species numbers recorded in this study (n = 60-87) show that old, low-productivity pine forests harbour a considerable fraction of the total diversity of Basidiomycetes in northern Fennoscandian boreal forests. We conclude that the formation of a framework linking forest history and environmental data is vital for understanding the ecology and formulating goals for future management of these forests.