Nutritional Management of Chronic Renal Disease in Dogs and Cats

Roles of plant-based ingredients and phytonutrients in canine nutrition and health

Dogs possess the ability to obtain essential nutrients, established by the Association of American Feed Control Officials (AAFCO), from both animal‐ and plant‐based ingredients. There has been a recent increase in the popularity of diets that limit or completely exclude certain plant‐based ingredients. Examples of these diets include ‘ancestral’ or ‘evolutionary’ diets, raw meat‐based diets and grain‐free diets. As compared to animal sources, plant‐derived ingredients (including vegetables, fruits, grains, legumes, nuts and seeds) provide many non‐essential phytonutrients with some data suggesting they confer health benefits. This review aims to assess the strength of current evidence on the relationship between the consumption of plant‐based foods and phytonutrients (such as plant‐derived carotenoids, polyphenols and phytosterols) and biomarkers of health and diseases (such as body weight/condition, gastrointestinal health, immune health, cardiovascular health, visual function and cognitive function) from clinical trials and epidemiological studies. This review highlights the potential nutritional and health benefits of including plant‐based ingredients as a part of balanced canine diets. We also highlight current research gaps in existing studies and provide future research directions to inform the impact of incorporating plant‐based ingredients in commercial or home‐prepared diets.

Evaluation of short-term risk factors associated with dehiscence and death following full-thickness incisions of the large intestine in cats: 84 cases (1993-2015)

OBJECTIVE

To evaluate short-term risk factors associated with dehiscence and death in cats undergoing full-thickness large intestinal incisions.

ANIMALS

84 client-owned cats that had undergone full-thickness large intestinal incisions and for which information regarding outcome through postoperative day 7 was available.

PROCEDURES

Medical records from 4 veterinary teaching hospitals were reviewed. For cats that met the inclusion criteria, signalment, history, laboratory test results, surgical and medical procedures, perioperative complications, and outcome were analyzed. A Fisher exact or Wilcoxon rank sum test was used to identify individual variables associated with dehiscence of intestinal incisions or patient nonsurvival to hospital discharge or both.

RESULTS

84 cats met the inclusion criteria. The overall dehiscence and survival to hospital discharge rates were 8.3% (7/84 cats) and 94% (79/84 cats), respectively. Factors associated with dehiscence and nonsurvival to hospital discharge included presence of band neutrophils, performance of partial colectomy with colonic resection and anastomosis, administration of blood products, postoperative cardiopulmonary arrest, and incisional inflammation or infection. Factors associated with nonsurvival to hospital discharge only included low serum globulin concentration, repair of colonic trauma or dehiscence, and postoperative colonic dehiscence. Factors associated with dehiscence only included hypoalbuminemia, renal dysfunction, administration of blood products or > 2 classes of antimicrobials, and intra-abdominal fecal contamination.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that intestinal dehiscence and mortality rates associated with large intestinal incisions in cats may be higher than previously proposed, although the risk of either outcome was still low. Factors suggestive of systemic illness were associated with colonic dehiscence or death, and focused prospective studies of risk factors are warranted.

Nutrient intake and influence on markers of oxidative stress in zoo-managed male snow leopards (Uncia uncia)

Oxidative stress (OS) results from the overproduction of reactive species. Nutrient intake can contribute positively or negatively to OS, and the lack of established nutrient requirements for most of the exotic species managed in zoos exacerbates the possibilities for nutrient imbalances that potentially could lead to reactive species production. The objective of this study was to evaluate the influence of nutrient intake and nutritional husbandry on markers of OS in male snow leopards (n = 14) maintained in U.S. facilities (n = 12). Diet samples and husbandry information were obtained and snow leopards were immobilized once for collection of blood. Samples were analyzed for chemical composition (diet and blood), antioxidant capacity (blood), and markers of OS (blood). Correlations between weekly nutrient intakes and markers of OS were analyzed by linear regression. Analyzed markers of OS included antioxidant enzymes (superoxide dismutase [SOD] and glutathione peroxidase [GPx]) and ferric reducing antioxidant potential that are protective against OS, and protein carbonyls, thiobarbituric acid reactive substances, and DNA/RNA damage that are indicative of oxidative damage. Weekly copper intake (10.1 to 80.2 mg) was negatively correlated with DNA/RNA damage (R² = 0.44; P = 0.01). Weekly sodium intake (4.4 to 12.7 g) was positively correlated with GPx activity (R² = 0.43; P = 0.04). More frequent feeding of whole prey (0.3 to 3 times/wk) was correlated with increased blood SOD activity (R² = 0.55; P < 0.01). In conclusion, greater dietary copper intake and more frequent feeding of whole prey may reduce OS in snow leopards. Dietary sodium intake and relationship with GPx activity should be further evaluated to determine benefit or detriment. No cause and effect can be inferred from our results, but our data suggest altering dietary form and nutrient concentrations may influence OS in snow leopards.

Evaluation of a novel non-surgical post-pyloric feeding technique in dogs with severe acute kidney injury

OBJECTIVES

To evaluate the placement and the performance of a new post-pyloric feeding (PPF) system, and compare it to esophageal (E) feeding in dogs with severe acute kidney injury (AKI).

DESIGN

Prospective study.

SETTING

University teaching hospital.

ANIMALS

Twenty client-owned dogs with severe AKI treated with hemodialysis.

INTERVENTIONS

Dogs were randomly assigned to 2 feeding techniques, PPF or E feeding; for PPF, an 8-Fr jejunal (J) tube was introduced through a standard 18-Fr E-tube and advanced endoscopically through the pylorus. A commercial liquid diet was administered at a continuous rate for at least 5 days. After the removal of the internal J-tube, feeding was continued through the E-tube. Control dogs were fed blended food 5 times daily through an E-tube. Placement technique, nutritional efficiency, and metabolic response to nutritional support were compared between the groups.

MEASUREMENTS AND MAIN RESULTS

Feeding tubes were placed a medium of 1 day (interquartile range, 0.8 d) after presentation. Median procedure-time in the group PPF was 26.5 min (11.5 min), including 8.5 min (2.7 min) for the E-tube and 17.5 min (5.0 min) for the J-tube. J-tubes were used for 5 days (1.5 d) with oral displacement observed in 3/10 dogs. The goal to administer 130% resting energy requirement within 3 days was reached in 13/20 dogs (8/10 PPF, 5/10 E). Despite nutritional support, dogs lost 1.2% body weight per day (1.1%), with no difference between the groups. The metabolic improvement was comparable between the groups, despite marked differences in the diet composition.

CONCLUSIONS

This new feeding technique can be recommended as an efficient method for early nutritional support in dogs with severe AKI. The protein-energy wasting observed despite active nutritional support suggests, however, the necessity for increased feeding targets or qualitative changes in diet composition for dogs with AKI.

A Retrospective Analysis of Complaints to RSPCA Queensland, Australia, about Dog Welfare

Simple Summary

Animal neglect and cruelty are important welfare and social issues, and dogs are one of the most commonly reported species to have experienced both. Most previous studies related to canine cruelty and welfare focused on animal abuse and dog fighting. However, literature dealing with the milder but more common forms of animal welfare concerns is limited. Therefore, this retrospective study aimed to understand the epidemiology of different types of canine welfare complaints in Queensland in the past decade and also to identify risk factors and their roles in different types of welfare complaints. The number of complaints received each year increased by 6.2% annually. The majority of complaints were neglect-related rather than related to deliberate cruelty, with the most common complaints being that dogs had poor body conformation, insufficient food and/or water, and receiving inadequate exercise. Poor living conditions and leaving dogs in a hot vehicle unattended were more commonly reported in recent years, potentially due to higher public awareness. Adult dogs that were reported were more likely to be alleged to have been poisoned, left unattended in a hot car, abandoned, and to have had inadequate exercise and shelter, compared with puppies. Puppies that were reported were more likely to be alleged to have experienced cruelty, lack of veterinary support, overcrowding, poor living and health conditions, and inappropriate surgery. Recognising which dogs are at most risk of cruelty will inform strategies to address this serious welfare problem.

Abstract

Animal neglect and cruelty are important welfare and social issues. We conducted an epidemiological study of dog welfare complaints and identified risk factors. The retrospective study included 107,597 dog welfare complaints received by RSPCA Queensland from July 2008 to June 2018. The risk factors considered were the age of dogs and the year of being reported. The number of complaints received each year increased by 6.2% per year. The most common complaints were poor dog body conformation, insufficient food and/or water, dogs receiving inadequate exercise, and dogs being confined or tethered. Increasing numbers were most evident for poor living conditions and leaving dogs in a hot vehicle unattended, both of which may have resulted from increasing public awareness. The majority of complaints were neglect-related rather than related to deliberate cruelty. Compared with puppies, adult dogs were more likely to be reported to have been poisoned, left unattended in a hot car or abandoned, as well as to have had inadequate exercise and shelter. Reported puppies were more likely to be alleged to have experienced cruelty, lack of veterinary support, overcrowding, poor living and health conditions, and inappropriate surgery. In conclusion, animal neglect was the most commonly reported welfare concern in dogs. Due to an assumed increasing public awareness of some types of cruelty, the trends of reported concerns differed. Adult dogs and puppies were reported to be involved in different types of welfare concerns. Strategies to address cruelty to dogs can be informed by an understanding of risk factors and trends in types of cruelty.

Retrospective study of mortality in Asiatic lions (Panthera leo persica) in the European breeding population between 2000 and 2014

Although the European population of Asiatic lions (Panthera leo persica) has been managed under the European Endangered Species Program (EEP) since 1990, little is known about the health status of the population. This study was designed to characterize mortality for this population through examination of the studbook and other records on 392 Asiatic lions living in the EEP between 2000 and 2014. A total of 270 animals died during the period with 80% of them being under 1 year old. The mortality rate for under 1 year olds was 54%, while the odds of survival of cubs within a litter increased if the dam had had litters previously. Survival to reproductive age was 44%. Post-mortem reports were requested and the cause of death was obtained for 133 animals. Trauma inflicted by a conspecific and lack of care were common causes of death (26% and 22%, respectively) and were also responsible for most of the neonatal mortalities. Congenital defects were responsible for 9% of deaths, although the true prevalence is likely underestimated. A common necropsy protocol for all Asiatic lion collections is needed to facilitate future studies. Zoo Biol. 36:66-73, 2017. © 2017 Wiley Periodicals, Inc.

THE PROTEIN METABOLISM IN SMALL ANIMALS WITH CHRONIC RENAL FAILURE AND ITS CORRECTION

Chronic renal failure (CRF) is often diagnosed in cats and dogs of old age. CRF is a consequence of metabolic deviations because of diseases (for example, generalized atherosclerosis, hypertensive disease, diabetes and others) and incorrect feeding. CRF is also a result of the delayed diagnosis of diseases of the urinary system and/or inadequate treatment. Aim of research. To study the biochemical parameters of protein metabolism that are important for determination of CRF stages and sub-stages in old small animals during correction of metabolic deviations. Materials and methods. There were analyzed biochemical indices (creatinine concentration in the blood serum; the ratio of protein/creatinine (UP/C) in the urine) and measured arterial blood pressure in 5 cats and 5 dogs with chronic renal failure selected from patients of the clinic according to medical history, clinical examination and special analysis. Results. It was analyzed CRF stages and sub-stages classification according to the International Renal Interest Society (IRIS). According to the date of creatinine concentration in the blood serum, CRF of the second stage was observed in 5 cats (140-250 μmol/L) and 3 dogs (125-180 μmol/L), and of the third stage - in 2 dogs (181-440 μmol/L). The CRF sub-stage as «without proteinuria» (UP/C < 0.2) was identified in 1 cat, «marginal proteinuria» (UP/C 0.2-0.4) – in 1 cat and «proteinuria» (UP/C > 0.4) - in 3 cats, and as «proteinuria» (UP/C > 0.5) - in 5 dogs. Conclusions. An important step of the successful treatment of CRF is the definition of the stages and sub-stages according to IRIS based mostly on the measurements of biochemical indices in the blood and urine of sick animals ‒ indicators of creatininemia and proteinuria, a change of which was caused mainly by metabolic processes of proteins under influence of exogenous factors (the traditional treatment of CRF plus enalapril and diet nutrition).

Kidney Disease and the Nexus of Chronic Kidney Disease and Acute Kidney Injury: The Role of Novel Biomarkers as Early and Accurate Diagnostics

Chronic kidney disease (CKD) and acute kidney injury (AKI) are interconnected and the presence of one is a risk for the other. CKD is an important predictor of AKI after exposure to nephrotoxic drugs or major surgery, whereas persistent or repetitive injury could result in the progression of CKD. This brings new perspectives to the diagnosis and monitoring of kidney diseases highlighting the need for a panel of kidney-specific biomarkers that reflect functional as well as structural damage and recovery, predict potential risk and provide prognosis. This article discusses the kidney-specific biomarkers, symmetric dimethylarginine (SDMA), clusterin, cystatin B, and inosine.

Dietary fibre and the importance of the gut microbiota in feline nutrition: a review

Domestic cats are obligate carnivores and in this light hindgut fermentation has been considered unimportant in this species. However, a diverse microbiota has been found in the small and large intestines of domestic cats. Additionally, in vitro and in vivo studies support the hypothesis that microbial fermentation is significant in felines with potential benefits to the host. Results on microbiota composition and microbial counts in different regions of the feline gastrointestinal tract are compiled, including a description of modulating host and technical factors. Additionally, the effects of dietary fibre supplementation on the microbiota composition are described. In a second section, in vitro studies, using inocula from fresh feline faeces and focusing on the fermentation characteristics of diverse plant substrates, are described. In vivo studies have investigated the effects of dietary fibre on a broad range of physiological outcomes. Results of this research, together with studies on effects of plant fibre on colonic morphology and function, protein and carbohydrate metabolism, and the effects of plant fibre on disease conditions that require a decrease in dietary protein intake, are shown in a third section of the present review. Conclusively, for fructans and beet pulp, for example, diverse beneficial effects have been demonstrated in the domestic cat. Both dietary fibre sources are regularly used in the pet food industry. More research is warranted to reveal the potential benefits of other fibre sources that can be used on a large scale in feline diets for healthy and diseased cats.

Nutritional concepts for the veterinary practitioner

Although veterinary practitioners know that nutrition can make a difference in the health and recovery from disease or illness in dogs and cats, they may feel poorly equipped to provide unbiased information on nutrition. This article provides information about evaluating and recommending diets and interpreting a pet food label to allow for comparisons among pet foods and discussion about how to do a nutritional assessment. It provides an example of how nutritional assessment and recommendation were successfully introduced into a busy private practice. Finally, some of the myths and misperceptions about nutrition are discussed with information provided from evidence-based research.

Macronutrients in feline health

Dietary macronutrients include protein, fat, and carbohydrates. Current nutritional recommendations establish minimums but not maximums for protein and fat but not for carbohydrates; thus, commercial feline maintenance diets have a wide range of macronutrient distribution depending on manufacturer, ingredients, and processing. There is growing interest and discussion, however, in defining the ideal macronutrient composition of feline diets to maximize longevity and health. Current recommendations should be tailored to each patient based on age, body condition, presence of muscle mass atrophy, and the presence of disease.

Hyperammonaemia in four cats with renal azotaemia

Hyperammonaemia is well reported in animals with advanced hepatic disease and portosystemic shunts, but is unreported in cats with renal disease. This case series describes four cats with severe renal azotaemia in which elevated ammonia levels were detected during the course of treatment. In two cases hyperammonaemia was detected at a time when neurological signs consistent with encephalopathy had developed. This raises the possibility that hyperammonaemia may play a role in the development of encephalopathy in cats with renal azotaemia.

Estudo da pressão arterial pelo método indireto oscilométrico (petmap®) em cães domésticos não anestesiados

O estudo das pressões arteriais sistólica, média, diastólica e da frequência cardíaca, pelo método indireto oscilométrico (petmap®), foi realizado em 150 cães atendidos pelo Serviço de Clínica Médica de Pequenos Animais da FMVZ - Unesp/Botucatu. Investigou-se a influência de fatores como presença do proprietário, estado de saúde, diagnóstico de doença renal, raça, idade, sexo, decúbito, contenção, fluidoterapia, condição corpórea, temperamento, atividade física, dieta e atitude associados ou não à elevação da pressão arterial. Dos 150 cães, 34% encontravam-se sob a categoria de risco mínimo para o desenvolvimento de lesões hipertensivas, 14,6% com hipertensão branda, 22,6% com hipertensão moderada e 28,66%, com hipertensão grave. Houve influência, dos fatores analisados, na elevação da pressão arterial de acordo com a categoria de risco.

Evaluation of recipes for home-prepared diets for dogs and cats with chronic kidney disease

OBJECTIVE

To evaluate recipes of diets recommended for animals with chronic kidney disease (CKD), compare nutritional profiles for those recipes to requirements for adult dogs and cats, and assess their appropriateness for the management of CKD.

DESIGN

Evaluation study.

SAMPLE

Recipes of 67 home-prepared diets promoted for use in dogs (n = 39 recipes) and cats (28) with CKD.

PROCEDURES

Recipes were analyzed with computer software to determine calories, macronutrient calorie distribution, and micronutrient concentrations and were assessed for appropriateness for the management of CKD.

RESULTS

Assumptions were required for the analysis of every recipe, and no recipe met all National Research Council nutrient recommended allowances (RA) for adult animals. Compared with RAs, concentrations of crude protein or at least 1 amino acid were low in 30 of 39 (76.9%) canine recipes and 12 of 28 (42.9%) feline recipes. Choline was most commonly below the RA in both canine (37/39 [94.9%]) and feline (23/28 [82.1%]) recipes; selenium (34/39 [87.2%] canine and 9/28 [32.1 %] feline recipes), zinc (24/39 [61.5%] canine and 19/28 [67.9%] feline recipes), and calcium (22/39 [56.4%] canine and 7/28 [25.0%] feline recipes) concentrations were also frequently below recommendations. The median phosphorus concentration in canine and feline recipes was 0.58 and 0.69 g/1,000 kcal, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Many problems with nutritional adequacy were detected, and use of the recipes could result in highly variable and often inappropriate diets. Many recipes would not meet nutritional and clinical needs of individual patients and should be used cautiously for long-term feeding.

Tolerability and efficacy of the intestinal phosphate binder Lantharenol® in cats

Background

Tolerability and efficacy of the intestinal phosphate binder Lantharenol^® (lanthanum carbonate octahydrate) were tested in two prospective, randomized and negative controlled laboratory studies with healthy adult cats fed commercial maintenance diets non-restricted in phosphorus. In the first study, the maximal tolerated dose was determined. Starting from a dose of 0.125 g/kg body weight mixed with the daily feed ration, the dose of Lantharenol^® was doubled every other week until signs of intolerability were observed (N = 10 cats compared to 5 untreated controls). In the second study, the effects of feed supplementation for two weeks with approximately 2, 6, and 20% of the maximal tolerated dose on phosphorus excretion patterns and balance were assessed (N = 8 cats per group).

Results

Lantharenol^® was found to be safe and well tolerated up to the dose of 1 g/kg bodyweight, corresponding to a concentration of 84 g Lantharenol^®/kg complete feed, defined as dry matter with a standard moisture content of 12%. Feed supplementation for two weeks with approximately 2-20% of this dosage (i.e., 1.6, 4.8, and 16 g/kg complete feed) resulted in a shift from urinary to faecal phosphorus excretion. Apparent phosphorus digestibility was dose-dependently reduced compared to the control group fed with diet only (N = 8).

Conclusions

The feed additive was well accepted and tolerated by all cats. Therefore, Lantharenol^® presents a well tolerated and efficacious option to individually tailor restriction of dietary phosphorus as indicated, for instance, in feline chronic kidney disease.

Azodyl, a synbiotic, fails to alter azotemia in cats with chronic kidney disease when sprinkled onto food

The effect of probiotic therapy in chronic kidney disease (CKD) in cats is poorly defined, but gaining in popularity. However, cat owners often prefer to administer probiotics by combining them with food, rather than administering capsules intact, as is prescribed by the manufacturer. The efficacy of such non-recommended administration is unknown. In this double-blinded, controlled clinical trial, 10 cats with naturally-occurring CKD were randomized to receive either a probiotic–prebiotic combination (synbiotic) or psyllium husk (prebiotic only) for 2 months. Medications were sprinkled and mixed into food or given as a slurry. Blood urea nitrogen (BUN) and creatinine were measured twice prior to administration of medication, and then monthly for 2 months during the medication administration. Owners and clinicians were masked as to treatment. The maximal percentage change in BUN and creatinine was calculated for each cat. No differences in percentage change were detected between groups ( P=0.8 for both BUN and creatinine). The synbiotic supplement used in this study, when applied to food or administered as a slurry fails to reduce azotemia in cats with CKD. Therefore, owners should not administer this synbiotic in this manner.

Case-control study of risk factors associated with feline and canine chronic kidney disease

An age-matched case-control study was initiated to determine the major risk factors associated with CKD in cats and dogs and to determine what clinical signs cat and dog owners observed before their veterinarian diagnosed their pet with CKD. When compared to controls, the feline cases were more likely to have had polydipsia and polyuria in the year before the owners' cats were diagnosed with CKD. In the dogs, increased water intake, increased urination, small size and a recent history of weight loss and bad breath were noticed by the dog owners before veterinary CKD diagnosis. Dog owners recognized abnormal drinking and urination behavior over half a year before their pet's veterinary diagnosis with CKD, and they recognized weight loss almost 4 months before CKD diagnosis. Bad breath was noticed 1.2 years before recognition of CKD by a veterinarian. Given that earlier CKD diagnosis should have been possible in most cases, clinical trials should proceed to measure the efficacy of early interventions.

American Association of Feline Practitioners: Senior Care Guidelines

Background Cats are the most popular pet in the United States and much of Northern Europe. Although 78% of owners consider their cats to be family members, many cats, particularly seniors, do not receive appropriate preventive care. 1 – 3 One of the main obstacles to owner compliance is the lack of a clear recommendation by the veterinary team. 4 Guidelines can help veterinarians to minimize this obstacle, strengthen the human-pet-veterinary bond, and improve the quality of life of cats.

Goals The goals of this article are to assist veterinarians to: Deliver consistent high-quality care to senior cats. Promote longevity and improve the quality of life of senior cats by: recognizing and controlling health risk factors; facilitating and promoting early detection of disease; improving or maintaining residual organ function; and delaying the progression of common conditions. Define aspects of screening, diagnosis, treatment and anesthesia of senior cats.

Gene therapy by electroporation for the treatment of chronic renal failure in companion animals

Background

Growth hormone-releasing hormone (GHRH) plasmid-based therapy for the treatment of chronic renal failure and its complications was examined. Companion dogs (13.1 ± 0.8 years, 29.4 ± 5.01 kg) and cats (13.2 ± 0.9 years, 8.5 ± 0.37 kg) received a single 0.4 mg or 0.1 mg species-specific plasmid injection, respectively, intramuscularly followed by electroporation, and analyzed up to 75 days post-treatment; controls underwent electroporation without plasmid administration.

Results

Plasmid-treated animals showed an increase in body weight (dogs 22.5% and cats 3.2%) compared to control animals, and displayed improved quality of life parameters including significant increases in appetite, activity, mentation and exercise tolerance levels. Insulin-like growth factor I (IGF-I, the downstream effector of GHRH) levels were increased in the plasmid treated animals. Hematological parameters were also significantly improved. Protein metabolism changes were observed suggesting a shift from a catabolic to an anabolic state in the treated animals. Blood urea nitrogen and creatinine did not show any significant changes suggesting maintenance of kidney function whereas the control animal's renal function deteriorated. Treated animals survived longer than control animals with 70% of dogs and 80% of cats surviving until study day 75. Only 17% and 40% of the control dogs and cats, respectively, survived to day 75.

Conclusion

Improved quality of life, survival and general well-being indicate that further investigation is warranted, and show the potential of a plasmid-based therapy by electroporation in preventing and managing complications of renal insufficiency.

The role of nutrients in modulating disease

The role of nutrition in the management of diseases has often centred on correcting apparent nutrient deficiencies or meeting estimated nutritional requirements of patients. Nutrition has traditionally been considered a supportive measure akin to fluid therapy and rarely it has been considered a primary means of ameliorating diseases. Recently, however, further understanding of the underlying mechanisms of various disease processes and how certain nutrients possess pharmacological properties have fuelled an interest in exploring how nutritional therapies themselves could modify the behaviour of various conditions. Nutrients such as omega-3 fatty acids, antioxidants and certain amino acids such as arginine and glutamine have all been demonstrated to have at least the potential to modulate diseases. Developments in the area of critical care nutrition have been particularly exciting as nutritional therapies utilising a combination of approaches have been shown to positively impact outcome beyond simply proving substrate for synthesis and energy. Application of certain nutrients for the modulation of diseases in veterinary patients is still in early stages, but apparent successes have already been demonstrated, and future studies are warranted to establish optimal approaches. This review describes the rationale of many of these approaches and discusses findings both in human beings and in animals, which may guide future therapy.