Equine viral vaccines: the past, present and future

The increasing international movement of horses combined with the relaxation of veterinary regulations has resulted in an increased incidence of equine infectious diseases. Vaccination, along with management measures, has become the primary method for the effective control of these diseases. Traditionally modified live and inactivated vaccines have been used and these vaccines have proven to be very successful in preventing disease. However, there are a number of equine infectious diseases for which conventional technology has shown its limitations. The advent of recombinant technology has stimulated the development of second generation vaccines, including gene deleted mutants, live vectored vaccines and DNA vaccines. These vaccines have in common that protective antigens are endogenously processed and presented along the molecules of the MHC I and MHC II complex, resulting in the stimulation of both humoral and cell-mediated immune responses similar to natural infection. The present paper provides a review of the vaccines being employed today against the most important equine viral diseases followed by a summary of new developments that are expected to bring improved vaccines to the market in the foreseeable future.     

A review of Dendromonocotyle (Monogenea: Monocotylidae) from the skin of stingrays and their control in public aquaria

Dendromonocotyle species (Monogenea: Monocotylidae) are the only monocotylids to parasitize the skin of chondrichthyan hosts. Currently 11 species are recorded from the skin of ray species in the Dasyatidae, Myliobatidae and Urolophidae. There have been increasing reports of Dendromonocotyle outbreaks on rays kept in public aquaria. This paper provides a broad review of Dendromonocotyle that should assist taxonomists and aquarists with species identification and help decisions on potential control methods for Dendromonocotyle infections. The taxonomy and host-specificity of Dendromonocotyle are discussed and a key to current species is provided. We summarise what little is known about the biology of Dendromonocotyle including egg embryonation and hatching, feeding, camouflage and reproduction. The efficacy of freshwater baths, chemical treatments and biological control measures such as the use of cleaner fish for Dendromonocotyle is also discussed. We demonstrate that effective control of Dendromonocotyle on captive rays is hampered by the lack of basic biological data on the life cycle of the parasites. A case history is provided outlining the success of a public aquarium (Underwater World, Mooloolaba, Queensland, Australia) in managing D. pipinna infections on captive Taeniura meyeni without chemical intervention simply by taking measures to reduce host stress.     

Virulence of recent and former classical swine fever virus isolates evaluated by their clinical and pathological signs

The clinical diagnosis of classical swine fever (CSF) still caused problems to the veterinarians during the last decade. The primary CSF outbreak was often detected too late and, meanwhile, the virus had spread. Consequently, the recent classical swine fever virus isolates (CSFV) were suspected to be of low virulence. The purpose of the study was to quantify the virulence of four recent CSFV by evaluating the clinical and pathological signs caused by different CSFV. Pigs of the same breed and age group were inoculated intranasally with CSFV from recent epidemics in European Union (EU) member states. The CSFV used are registered in the data base of the EU Reference Laboratory for CSF and belong to different genotypes: 2.1, 2.2 and 2.3 respectively. Clinical signs of CSF were evaluated by using a score system suggested previously (Mittelholzer et al., 2000: Vet. Microbiol. 74, 293). For the evaluation of pathological lesions, a new pathological score was introduced. The four CSFV tested here were classified as moderately virulent in general, although one CSFV may cause different clinical courses, ranging from highly virulent to avirulent. This indicates the importance of additional factors in the host animal for virulence. Differences in the clinical and pathological signs between these four recent CSFV were rather minor, emphasizing that the genetic typing of CSFV is absolutely essential. Differences towards former CSFV (e.g. reference virus strain Alfort 187) were more pronounced, especially regarding the onset and duration of the disease, the occurrence of skin haemorrhages and pathological lesions of kidney, subcutis and serosae. It is concluded that clinical diagnosis of CSF is rather difficult in pigs up to 14 days post-CSFV infection using these four CSFV, emphasizing the need for careful differential diagnosis and the laboratory investigation for CSF at an early stage.     

Nitrogen metabolism and growth performance of gilts fed standard corn-soybean meal diets or low-crude protein,amino acid-supplemented diets

Two experiments were conducted to determine the CP concentration below which N retention and growth performance are reduced when low-protein, amino acid-supplemented, corn-soybean meal diets are fed. In a N balance trial (Exp. 1), 12 gilts (initial weight 41 kg) were fitted with urinary catheters and fed six different diets during three 7-d periods in an incomplete block design. The diets were: 1) 18% CP; 2) 14% CP + AA, 3) 16% CP; 4) 12% CP + AA; 5) 14% CP; and 6) 10% CP + AA. Amino acids (lysine, threonine, tryptophan, and methionine) were supplemented such that the concentrations in the low-protein diets were equal to those in their standard (4% CP higher) counterparts. Nitrogen retention (g/d) decreased (P < 0.01) as CP decreased, in both standard (27.10, 24.53, and 20.99) and low-protein (21.51, 19.18, and 15.83) diets, but was lower (P < 0.01) in low-protein diets. There were no differences among treatments (P > 0.05) in biological value (68.2% standard vs 71.0% low-protein). In a growth performance trial (Exp. 2), 36 gilts (initial weight 19.5 kg) were penned individually and fed one of six diets for 35 d in a randomized complete block design. Dietary treatments were a 16% CP standard diet and low-protein diets formulated to contain 15, 14, 13, 12, and 11% CP supplemented with crystalline lysine, tryptophan, threonine, and methionine to equal the total concentrations in the standard diet. Protein concentration affected (P < or = 0.05) ADG, ADFI, feed efficiency, fat-free lean gain, longissimus muscle area, plasma urea, and plasma concentrations of most essential AA. For most of these traits, the major difference was poor performance of pigs fed the 11% CP diet. Thus, in Exp. 1, at AA concentrations from deficient to excess, low-protein, amino acid-supplemented diets failed to produce the same N retention as the equivalent corn-soybean meal diets. However in Exp. 2, the same performance was obtained with 16, 15, 14, 13, and 12% CP. Based on these data, we suggest that N balance is more sensitive than growth to amino acid adequacy andthat other AA (e.g., isoleucine and valine) may limit growth performance when the protein concentration is reduced by more than four percentage units.     

Concurrent administration of water-soluble vitamin E can increase the oral bioavailability of cyclosporine a in healthy dogs

Randomized crossover studies were performed to determine the effect of coadministration of d-alpha-tocopheryl polyethylene glycol 1,000 succinate (vitamin E TPGS) on the oral bioavailability of cyclosporine A (CsA) formulated as either Sandimmune (Novartis Pharmaceuticals) or Neoral (Novartis Pharmaceuticals). Healthy dogs were given a single oral dose of each cyclosporine formulation with and without vitamin E TPGS. Blood samples were collected from each dog before and at various intervals for 24 hours after drug administration. Whole-blood CsA concentrations were determined by high-pressure liquid chromatography. Noncompartmental pharmacokinetic analysis showed that coadministration of vitamin E TPGS increased the oral bioavailability of Sandimmune. The bioavailability of Neoral was greater than that of cyclosporine. Concurrent administration of vitamin E TPGS had no consistent effect on the bioavailability of Neoral.     

Metastatic calcification in a dog attributable to ingestion of a tacalcitol ointment

A 22-week-old 21-kg female Bernese Mountain Dog ingested a topical antipsoriatic preparation containing the synthetic vitamin D analog tacalcitol. The dog died after a history of lethargy, recumbency, paresis of the hindlimbs, increased rectal temperature, dyspnea, and hematemesis. Histologic examination revealed metastatic calcification in the kidneys, lungs, myocardium, brain, stomach, and tear glands. The appearance of soft tissue mineralization in multiple organs is consistent with hypercalcemia derived from excessive vitamin D uptake. Oral toxicity studies for tacalcitol in the dog are not available, but the present report emphasizes the extraordinary toxic risk of drugs containing this vitamin D analog to dogs.     

Identification and Spread of Fomitiporia punctata Associated with Wood Decay of Grapevine Showing Symptoms of Esca

ABSTRACT A full understanding of the pathology of esca, a chronic disease of grapevines, has been problematic, in part because the identity of the pathogen (or pathogens) has been difficult to determine. The wood decay symptoms of esca have been most often associated with Phellinus igniarius or Fomitiporia punctata. However, Koch's postulates have not been completely fulfilled because symptoms take many years to develop. The goal of this study was to determine the identity and mode of spread of basidiomycetes associated with wood decay in vines showing esca symptoms in Italian vineyards. Vineyards were intensively studied for the presence of basidiocarps, and mycelium was isolated from symptomatic vines. Fruiting bodies were identified by morphology, while mycelial isolates were identified by restriction fragment length polymorphism analysis of the internal transcribed spacer region of the nuclear ribosomal RNA gene cluster. Fomitiporia punctata fruiting bodies and mycelium were associated with approximately 50% of the vines showing esca symptoms in two vineyards; P. igniarius was not found in any samples. Fruiting bodies of F. punctata were found in five of six vineyards examined, but at low frequencies except in one vineyard. The diversity of somatic incompatibility types was very high; isolates from almost every vine had different somatic incompatibility types. With few exceptions, symptomatic and dead vines were not spatially aggregated within 12 vineyards. The combination of diverse somatic incompatibility types and lack of spatial aggregations are not consistent with the hypothesis that the disease is spread clonally through roots or by pruning tools. The correct identity of basidiomycetes associated with wood decay of vines with esca symptoms is important for understanding the epidemiology of this disease because F. punctata is found commonly on many woody hosts in Europe, which may represent a potential inoculum source for this disease.     

Efficacy of an ivermectin and pyrantel pamoate combination against adult hookworm, Ancylostoma braziliense, in dogs

A chewable tablet incorporating ivermectin and pyrantel was tested in 12 Beagle dogs for efficacy against the adult hookworm, Ancylostoma braziliense. The dogs were administered infective larvae of A braziliense orally. Twenty-one days after infection the dogs were weighed and allocated randomly to receive either an oral treatment with ivermectin and pyrantel in a beef-based chewable tablet or no treatment. The chewable tablet was a commercially available product, which was made to deliver ivermectin at 6 μg/kg and pyrantel at 5.0 mg/kg to each dog. Seven days after treatment the dogs were euthanased, necropsied, and examined for adult hookworms. At necropsy, no adult A braziliense was observed in any of the 6 treated dogs and all 6 dogs that had been left untreated were infected with adult A braziliense (range, 48 to 161). It was concluded that this combination product is 100% efficacious against adult A braziliense.     

MAGNETIC RESONANCE IMAGING OF THE BRAIN AND COELOMIC CAVITY OF THE DOMESTIC PIGEON (Columba livia domestica)

The technical feasibility of performing magnetic resonance imaging (MRI) in domestic pigeons was investigated. Imaging was performed with a 1.5 Tesla magnet using a human knee surface coil. The head and coelomic cavity of isoflurane-anesthetized birds were imaged in the dorsal, sagittal, and transverse planes to produce T1-weighted, T2-weighted, and contrast-enhanced T1-weighted images. The birds were then euthanatized, formalin perfused, frozen, and sectioned in the corresponding anatomic planes. The anatomy defined by MRI was correlated with gross anatomic sections made from the same birds. The following CNS structures were identified: cerebral hemispheres, cerebellum, optic chiasm, optic lobes, brain stem, and cranial spinal cord. The cornea, lens, and vitreous were also well differentiated in dorsal section MRI's. The abdominal organs identified included proventriculus, ventriculus, intestines, cloaca, liver, kidneys, spleen, testes, and ovary. The hepatic and renal vasculature were well defined.