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    The nutritional management of food hypersensitivity in dogs and cats : an assessment of a protein hydrolysate : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Veterinary Science at Massey University
    (Massey University, 2001) Cave, Nicholas J
    Adverse reactions to food are exceedingly common reasons for the presentation of cats and dogs to veterinarians. Of those cases, a relatively small number involve a truly immune-mediated reaction to the food substance. However, differentiating those that are from the more common food intolerances is usually difficult and often impossible. In addition, certain individuals with a true food hypersensitivity are difficult to manage with conventional diets. The identification and availability of nutritionally complete commercially prepared diets with a protein component that is truly novel to the patient under investigation is often the stumbling block to successful diagnosis and management of food hypersensitivity. The recent development of protein hydrolysate based pet foods for dogs and cats provides an exciting tool for more reliable diagnosis and management or food hypersensitivity in those species. Chapter 1 of this thesis describes the immunological and pathophysiological basis of food hypersensitivity and presents some of the key areas of recent research that have lead to a deeper, if still incomplete understanding of the aetiological mechanisms responsible. The development and maintenance of oral tolerance is discussed including the key roles that the resident antigen presenting cells in the mucosa play. From that description follows a presentation of some of the current hypotheses regarding mechanisms by which oral tolerance is lost or not established. These include the action of mucosal adjuvants, parasitism, IgA deficiency and alterations in mucosal permeability. Building on this discussion is an examination of the methods currently available to veterinarians for the diagnosis of food hypersensitivity, their clinical usefulness and limitations. The importance of obtaining a complete and accurate dietary history is emphasized. The difficulties in doing so and the consequences of not doing so are discussed. As stated, the recent development of diets in which the protein content has been hydrolysed provides a new tool for the veterinarian. Some of the practical aspects behind producing hydrolysate diets are presented and the theoretical basis, especially the importance of the molecular weight of remaining polypeptide fragments, is emphasized. Finally recommendations as to their use and the role that they may play in the future are discussed. Chapter 2 describes the initial assessment of 2 candidate hydrolysates, one made from fish and the other from chicken proteins. The method used for this initial experiment was high-performance size-exclusion liquid chromatography. The investigation revealed the chicken hydrolysate to have the more favourable molecular weight profile of the two. The finding that 92.9% of the hydrolysate was of a molecular weight less than 5kDa is supportive of its potential value in a hypoallergenic diet. The molecular weight profile was then compared with a selection of those published in the human medical literature. Cow's milk hydrolysates have been widely available and used for the past 2-3 decades. The chicken hydrolysate appeared to compare very favourably to a number of extensively hydrolysed human infant formulae that have been demonstrated experimentally and clinically to be truly hypoallergenic. Despite the extensive use of molecular weight profiles to compare hydrolysates, they remain unreliable as predictors of allergenicity. Chapter 3 describes the experimental evaluation of the antigenicity of the chicken hydrolysate. Following successful immunization of dogs to the intact parent protein, an IgG inhibition ELISA was developed using sera from the immunized dogs. It was demonstrated that the hydrolysate retained some ability to bind IgG but that at equal levels of antibody binding, the concentration of the hydrolysate solution required was 66 times greater than that of the intact parent protein. It is likely that this represents a clinically highly significant reduction in antigenicity. Of the limitations of the inhibition ELISA study, perhaps the greatest from the perspective of hydrolysate diet analysis is its inability to differentiate the molecular weight of the IgG-binding fragments. This is important since if they are less than 6-10kDa, they are unlikely to participate in IgE-mediated allergic reactions. Chapter 4 describes the experiment chosen to determine the size of the remaining IgG-binding fragments, namely Western blotting. It was established that the major antigenic fraction remaining in the parent protein following SDS-PAGE separation was a c.69kDa protein consistent with chicken serum albumin. It was demonstrated by both the Western blotting and the HP-SEC that this antigen was absent from the hydrolysate. The actual size of the few remaining binding fragments in the hydrolysate was not, however, clearly elucidated. It was concluded that the chicken hydrolysate assessed during this thesis is a promising candidate for inclusion as the peptide component of a diet for the diagnosis and management of food hypersensitivity in dogs and cats. In addition, the diet has theoretical promise for the prevention of food hypersensitivity during periods of mucosal inflammation such as idiopathic inflammatory bowel disease and acute gastroenteritis. Ultimately, clinical trials are required to conclusively demonstrate the value of the hydrolysate in the diagnosis and management of these disorders.
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    Intraperitoneal nutrition in dogs : a possible alternative for nutritional support : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University
    (Massey University, 1999) Halsey, Todd R
    Prolonged protein-energy malnutrition in dogs and other species has serious and wide-ranging adverse effects on organ systems. Separating the effects of poor nutritional status from those of the underlying disease mechanism is difficult and has made documenting a significant improvement in the long-term survival of patients frustrating. Despite these problems, nutritional support continues to be an important component of the treatment in critically ill or injured patients. In Chapter 1 the consequences of prolonged malnutrition throughout the body are discussed and the methods of providing nutritional support assessed. For patients who have a functioning gastrointestinal tract (GIT), nutritional support should be provided so that as much of the GIT as possible is used. In companion animals, enteral nutrition can be provided in various ways, ranging from forced oral feeding to an indwelling jejunostomy tube. Enteral nutritional support is a more physiological route for nutrient absorption, is less likely to result in serious adverse effects and is cheaper than parenteral nutrition. However, there are circumstances under which the GIT cannot be utilised as the primary route for nutritional support. This prompted the development of intravenous parenteral nutrition. Administration of total daily caloric requirements necessitates the use of a central venous line and a continuous 18 to 24 hour infusion. Unfamiliarity with central venous catheters, expensive and the inability to provide 24 hour monitoring for critically ill patients has precluded the use of intravenous parenteral nutrition in many veterinary hospitals. For these reasons alternative routes of nutritional support have been examined. Chapter 2 examines the work achieved over the past 20 years by workers who have investigated the peritoneal cavity as an alternative route for parenteral nutritional support. The peritoneum is capable of absorbing electrolytes, dextrose, complex carbohydrates, amino acids, intact plasma proteins, lipids and particulate matter. Previous studies using experimental animal models have demonstrated that intraperitoneal nutritional support is feasible. The pilot study (Chapter 3) in this experimental series examined the physical, haematological, biochemical and peritoneal cytological response in dogs receiving a total nutrient admixture (TNA) comprised of dextrose, amino acids and a lipid emulsion administered into the peritoneal cavity by a repeat puncture technique. This study identified a number of significant adverse effects associated with intraperitoneal nutrition (IPN) when using a TNA given in sufficient quantities to meet 100% of daily energy requirements (RER). Acute non-septic peritonitis, hypoalbuminaemia, mild anaemia, electrolyte and glucose derangements, and sudden fluid shifts from the vascular space into the peritoneal cavity were the problems recognised. The study reported in Chapter 4 was undertaken to investigate the cause of the marked peritoneal inflammatory response and to pursue possible explanations lor the clinicopathological changes that occurred in the pilot study. This was achieved by administering the components of the TNA as individual nutrients and comparing the peritoneal response over a 5 day period. This study demonstrated that the lipid component of the TNA was responsible for the majority ot the peritoneal inflammation seen in the pilot study, causing a 13 fold greater increase in peritoneal total white cell count (TWCC) compared to a 5% amino acid solution and a 10% dextrose solution. Although there was a significant increase in peritoneal TWCC in dogs receiving the lipid emulsion, there were no signs supportive of a clinically significant peritonitis at the dose administered. The mild anaemia, hypoproteinaemia (particularly hypoalbuminaemia) and electrolyte disturbances noted in the pilot study were again seen in the study described in this chapter. Although well tolerated by the peritoneal cavity, 10% dextrose in the volume administered in Chapter 4 failed to supply enough calories on a daily basis to make this route of nutritional support feasible. It was decided to try and increase the percentage of daily caloric requirements supplied by using a dextrose polymer. This nutrient solution allowed more calories to be provided for a given osmolality without the risk of fluid shifts into the peritoneal cavity because of it's isotonic nature. The study presented in Chapter 5 identified that a 21.5% dextrose polymer solution caused an initial significant increase in peritoneal TWCC, which then declined to near baseline concentrations by the end of the study. It was concluded that twenty percent of resting energy requirements can be safely given to clinically healthy dogs in the form of a 10% dextrose solution, 5% amino acid solution, 10% lipid emulsion and a 21.5% dextrose polymer solution via a repeat abdominal puncture technique. Further studies are required before this form of nutritional support can be widely recommended to the veterinary profession.
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    Papillomaviruses in dogs and cats.
    (2017-07) Munday JS; Thomson NA; Luff JA
    Papillomaviruses (PVs) cause disease in both dogs and cats. In dogs, PVs are thought to cause oral papillomatosis, cutaneous papillomas and canine viral pigmented plaques, whereas PVs have been rarely associated with the development of oral and cutaneous squamous cell carcinomas in this species. In cats, PVs are currently thought to cause oral papillomas, feline viral plaques, Bowenoid in situ carcinomas and feline sarcoids. Furthermore, there is increasing evidence that PVs may also be a cause of cutaneous squamous cell carcinomas and basal cell carcinomas in cats. These diseases are discussed in this review. Additionally, there is a brief overview of PV biology, including how these viruses cause disease. Diagnostic techniques and possible methods to prevent PV infection are also discussed.