Immunotherapy for canine cancer – Is it time to go back to the future?

Over the last 50 years, the significance of the immune system in the development and control of cancer has been much debated. However, recent discoveries provide evidence for a role of immunological mechanisms in the detection and destruction of cancer cells. Forty years ago veterinary oncologists were already investigating the feasibility of treating neoplasia by enhancing anticancer immunity. Unfortunately, this research was hindered by lack of a detailed understanding of cancer immunology, this limited the specificity and success of these early approaches. The great forward strides made in our understanding of onco‐immunology in recent years have provided the impetus for a resurgence of interest in anticancer immunotherapy for canine patients. In this article both these initial trials and the exciting novel immunotherapeutics currently in development are reviewed.     

An update on canine cardiomyopathies – is it all in the genes?

Dilated cardiomyopathy is the second most common cardiac disease in dogs and causes considerable morbidity and mortality. Primary dilated cardiomyopathy is suspected to be familial, and genetic loci have been associated with the disease in a number of breeds. Because it is an adult‐onset disease, usually with late onset, testing breeding dogs and bitches before breeding for a genetic mutation that could lead to dilated cardiomyopathy would be helpful to prevent disease. There is growing evidence that the genetic basis may be multigenic rather than monogenic in the majority of studied breeds. This review article describes the known genetic aspects of canine dilated cardiomyopathy and the implications of genetic tests on heart testing and the future of veterinary cardiology.     

The future of radiotherapy in small animals – should the fractions be coarse or fine?

Radiation therapy has been used to treat animal cancers for more than 100 years. Clinical experiences and experimental results have been widely published and provide a basis for the recognition of radiation therapy as an integral component of multimodal cancer management in veterinary oncology. As the expectations of pet owners and the demand for treatment of companion animals with cancer have increased, veterinary oncology itself has undergone dramatic advances in the past several decades both in terms of improved diagnostics and treatments, including increased accessibility of radiation therapy. Synchronous with development of the specialism of veterinary radiation oncology, confusion and controversy have arisen with regard to distinguishing between different types of radiotherapy and methods of treatment delivery. Importantly, the confusion extends beyond semantics, and includes opinionated debate about defining which forms of therapy (if any at all) are optimal for a given patient. This exemplifies how, despite marks of maturity including age and a robust publication history, the field of veterinary radiation oncology is in some ways still in its infancy. The purpose of this article is to review the evidence base for daily (fine) fractionation versus weekly (coarse) hypofractionation in veterinary oncology, using selected tumour types as examples.     

Endotracheal intubation in horses – are complications truly rare?

Endotracheal intubation is an essential component of general anaesthesia in horses to facilitate delivery of inhalation anaesthetic agent and oxygen, artificial ventilation, and prevent pulmonary aspiration of blood or gastric reflux. Experimental studies have identified a high incidence of tracheal mucosal injury after intubation resulting from direct trauma or local ischaemia from the pressure of the inflated cuff. Recommendations to minimise injury include gentle intubation, disconnection from the anaesthesia machine when moving the horse, and monitoring the endotracheal tube cuff pressure. New studies are needed to evaluate trachea and cuff pressure interactions under current practice conditions, including specialised ventilation modalities such as positive end‐expiratory pressure and continuous airway pressure.     

Can ventricular function be assessed by echocardiography in chronic canine mitral valve disease?

Mitral regurgitation (MR) related to chronic degenerative valvular disease is the most important cause of heart failure in dogs. Ultrasound examination of the heart can identify valve lesions, confirm the presence of valvular regurgitation, document cardiac remodeling, estimate intracardiac pressures, and quantify systolic ventricular function. These findings can influence prognosis or selection of medical therapy. Reductions in ventricular systolic function may be detected on serial echocardiographic examinations in some dogs with MR. However the changes in ventricular loading that accompany MR often complicate these measurements. For example, shortening and ejection fractions are often increased in severe MR, even in the setting of congestive heart failure. Echocardiography with Doppler is also used to assess ventricular diastolic function and filling pressures. This information helps predict the risk of congestive heart failure. However these findings are often rendered ambiguous by age-related impairment of ventricular relaxation, elevations in left atrial pressure due to MR, and effects of volume overload on myocardial tissue velocities. These factors limit the usefulness of ventricular filling and tissue velocities, as well as derived ratios such as the E/E' ratio, for predicting congestive heart failure in MR. More advanced Doppler and tissue echocardiographic methods, as well as prospective clinical studies, are needed to reduce the ambiguity involved with assessment of ventricular function and filling pressures in the setting of MR.     

Desmoplakin and Plakoglobin – Specific Markers of Lymphatic Vessels in the Skin?

Monoclonal antibodies against Desmoplakin and Plakoglobin were tested for their suitability as specific markers of lymphatic vessels. The tissue samples were taken from horse skin in an attempt to establish the horse as a model for human lymphatic diseases. To obtain a clear, positive identification of blood and lymphatic vessels, immunohistochemical staining with antibodies against vascular endothelial growth factor receptor 3 (VEGFR-3) and platelet endothelial adhesion molecule (PECAM-1, CD31), was compared with Desmoplakin and Plakoglobin. Because anti-VEGFR-3 is specific for lymphatic vessels in the skin while anti-CD31 stains blood and lymphatic vessels as well, it can be concluded that VEGFR-3(-)/CD31(+) vessels are blood vessels and VEGFR-3(+)/CD31(+) vessels are lymphatic vessels. It was documented on serial sections that Plakoglobin stains both blood and lymphatic vessels. However, Desmoplakin did not stain several positively identified lymphatic vessels. Therefore, Desmoplakin and Plakoglobin antibodies are not specific markers of lymphatic vessels in the skin and the staining pattern is tissues and species dependent.     

Zinc metabolism--a factor in canine aggression?

In order to test the hypothesis of zinc-deficiency as a factor in canine aggression, we examined sera of dangerously aggressive dogs and of behaviourally normal (non-aggressive) dogs for their zinc-contents. The results showed distinctly higher zinc-concentrations (mean +/- SD) in aggressive dogs (1.69 +/- 0.49 micrograms/ml) than in normal non aggressive dogs (0.76 +/- 0.16 microgram/ml).     

Is it possible to diagnose canine hypothyroidism?

A definitive diagnosis of hypothyroidism can be difficult because of the many clinical abnormalities associated with thyroid hormone deficiency, and the lack of readily available diagnostic tests with high sensitivity and specificity. Thyroid function tests should be performed only in dogs with clinical findings consistent with hypothyroidism. Measurement of serum total thyroxine (T4) concentration is a useful initial screening test since most hypothyroid dogs have values below the reference range. Serum free T4 concentration measured by equilibrium dialysis is a more sensitive and specific test of thyroid function than total T4 and is particularly useful in dogs with non-thyroidal illness or atypical clinical signs. Measurement of serum endogenous thyroid-stimulating hormone concentration is also helpful, but many hypothyroid dogs have normal results. The gold standard for diagnosis of hypothyroidism remains the thyroid-stimulating hormone response test. It should be used to confirm hypothyroidism when other tests do not agree with the clinical impression or if atypical signs or non-thyroidal illness exist or there has been administration of drugs known to alter thyroid function tests. Ultimately, a positive response to treatment is expected in hypothyroid dogs treated appropriately with levothyroxine.