Food Hypersensitivity Reactions in Soft Coated Wheaten Terriers with Protein-Losing Enteropathy or Protein-Losing Nephropathy or Both: Gastroscopic Food Sensitivity Testing, Dietary Provocation, and Fecal Immunoglobulin E

Retrospective evaluation of the etiology and clinical characteristics of peripheral edema in dogs

BACKGROUND

The prevalence and clinical characteristics of different etiologies of peripheral edema in dogs are unknown.

HYPOTHESIS/OBJECTIVES

To determine the prevalence of different etiologies of peripheral edema, describe clinical characteristics that vary among etiologies, and report survival times.

ANIMALS

Five hundred twenty-seven dogs with peripheral edema.

METHODS

Retrospective medical record review. Differences in clinical variables among etiology groups were assessed by Kruskal-Wallis testing with post hoc pairwise Dunn's testing and Chi-square testing with Monte Carlo simulation.

RESULTS

The most common etiologies of peripheral edema in dogs were vasculitis (n = 193, 37%), lymphatic/venous obstruction (LVO; 114, 22%), and hypoalbuminemia (94, 18%). Right-sided congestive heart failure (R-CHF) was uncommon (25, 5%). Edema was localized in 377 (72%) dogs and generalized in 142 (27%) dogs, and hypoalbuminemia was more likely to cause generalized edema compared to LVO or vasculitis (P < .0001). Concurrent abdominal effusion (155, 29%) was more common than pleural (77, 15%) or pericardial (12, 2%) effusion. Abdominal and pleural effusion occurred more commonly in dogs with hypoalbuminemia or R-CHF compared to LVO or vasculitis (P < .0001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Distribution of edema, concurrent cavitary effusions, and clinicopathological data can help predict the underlying etiology of peripheral edema in dogs.

Canine chronic enteropathy—Current state-of-the-art and emerging concepts

Over the last decade, chronic inflammatory enteropathies (CIE) in dogs have received great attention in the basic and clinical research arena. The 2010 ACVIM Consensus Statement, including guidelines for the diagnostic criteria for canine and feline CIE, was an important milestone to a more standardized approach to patients suspected of a CIE diagnosis. Great strides have been made since understanding the pathogenesis and classification of CIE in dogs, and novel diagnostic and treatment options have evolved. New concepts in the microbiome-host-interaction, metabolic pathways, crosstalk within the mucosal immune system, and extension to the gut-brain axis have emerged. Novel diagnostics have been developed, the clinical utility of which remains to be critically evaluated in the next coming years. New directions are also expected to lead to a larger spectrum of treatment options tailored to the individual patient. This review offers insights into emerging concepts and future directions proposed for further CIE research in dogs for the next decade to come.

Current diagnostics for chronic enteropathies in dogs

Chronic enteropathies (CEs) in dogs describe a group of idiopathic disorders characterized by chronic persistent or recurrent gastrointestinal (GI) signs. Three major subgroups of CE can be identified by their response to treatment: Food-responsive disease (FRD), antibiotic-responsive disease (ARD), and steroid-responsive disease (SRD). The clinical diagnosis of CE is made by exclusion of all other possible causes of chronic diarrhea and includes histologic assessment of intestinal biopsies. The process of diagnosing canine CE can therefore be very time-consuming and expensive, and in most cases, does not help to identify dogs that will respond to a specific treatment. The development of novel diagnostic tests for canine CE has therefore focused on the accuracy of such tests to predict treatment responses. In this article, several novel assays that have the potential to become commercially available will be discussed, such as genetic tests, perinuclear anti-neutrophil cytoplasmic antibodies (pANCA), antibodies against transglutaminase/gliadin, antibodies against E coli OmpC/flagellin, and micro RNAs.

Critically appraised topic on adverse food reactions of companion animals (9): time to flare of cutaneous signs after a dietary challenge in dogs and cats with food allergies

BACKGROUND

At this time, elimination diets followed by oral food challenges (OFCs) represent the "gold standard" for diagnosing skin-manifesting food allergies (FA) in dogs and cats. Regrettably, there is no clear consensus on how long one should wait for clinical signs to flare after an OFC before diagnosing or ruling-out a FA in a dog or a cat.

RESULTS

We searched two databases on October 23, 2019 to look for specific information on the time for a flare of clinical signs to occur during OFCs after elimination diets in dogs and cats with skin-manifesting FAs. Altogether, we reviewed the study results of nine papers that included 234 dogs and four articles containing data from 83 cats. As multiple OFCs could be done in the same patient and not all animals included were subjected to an OFC, we were able to compile 315 and 72 times to flare (TTF) after an OFC in dogs and cats, respectively. When regrouping all cases together, about 9% of dogs and 27% of cats exhibited a flare of clinical signs in the first day after an OFC; 21% of dogs and 29% of cats had such relapse by the end of the second day. The time needed for 50 and 90% of dogs to exhibit a deterioration of clinical signs (TTF50 and TTF90) was 5 and 14, respectively; in cats, these times were 4 and 7 days, respectively. By 14 days after an OFC, nearly all food-allergic patients from both species had had a relapse of clinical signs. These results are limited by the likely under-reporting of flares that occur on the first day immediately following an OFC, the time in which IgE-mediated acute allergic reactions typically develop.

CONCLUSION

Veterinary clinicians performing an OFC need to wait for 14 and 7 days for more than 90% of dogs and cats with a skin-manifesting FA to have a flare of clinical signs, respectively.

Critically appraised topic on adverse food reactions of companion animals (6): prevalence of noncutaneous manifestations of adverse food reactions in dogs and cats

BACKGROUND

Many reports describe the cutaneous signs of adverse food reactions (AFR) in the dog and cat. However, various non-cutaneous clinical signs are less well described. Our objective was to systematically evaluate these non-cutaneous signs of AFR in small animals.

RESULTS

We searched two databases (MEDLINE and Web of Science) for pertinent references on non-cutaneous signs of adverse food reactions. Among 117 and 764 articles found in the MEDLINE and Web of Science databases, respectively, we selected 47 articles that reported data related to non-cutaneous clinical signs of AFR. Gastrointestinal signs, symmetrical lupoid onychitis, conjunctivitis, sneezing, and anaphylaxis were reported to be associated with AFR in dogs and gastrointestinal and respiratory signs, conjunctivitis, and hyperactive behaviour in cats. In Border terriers with paroxysmal gluten-sensitive dyskinesia, an underlying AFR should be considered. Of these clinical signs diarrhoea and frequent defecation were most frequently reported to be diet-responsive in dogs; in the cat, these were vomiting and diarrhoea.

CONCLUSIONS

An elimination diet should be considered early in the work-up of dogs and cats with chronic vomiting and diarrhoea. Other non-cutaneous signs occur less commonly because of AFRs.

Thromboelastometric assessment of hemostasis following hydroxyethyl starch (130/0.4) administration as a constant rate infusion in hypoalbuminemic dogs

BACKGROUND

The primary aim was to evaluate by means of thromboelastometry (ROTEM) the effects of hydroxyethyl starch (HES) 130/0.4 administered as a constant rate infusion (CRI) on hemostasis in hypoalbuminemic dogs. The second aim was to use ROTEM analysis to detect whether all hypoalbuminemic dogs of our population were hypercoagulable.

RESULTS

The study sample was 20 hypoalbuminemic dogs (albumin < 2 g/dl) with normal perfusion parameters and requiring intravenous fluid therapy. In order to support plasma colloid osmotic pressure, in addition to crystalloid, HES 130/0.4 was administered as a constant rate infusion at 1 ml/kg/h (group 1, n = 11) or 2 ml/kg/h for 24 h (group 2, n = 9). Blood samples were collected at baseline (T0) and 24 h postinfusion (T1); coagulation was assessed by standard coagulation profile (prothrombin time, activated partial thromboplastin time, and fibrinogen), and ROTEM analysis (in-TEM®, ex-TEM® and fib- TEM® profile). No statistically significant differences in ROTEM values in group 1 were observed (P > 0.05), whereas in group 2 statistically significant differences (P < 0.05) were found at T1 in the in-TEM® profile [decrease in clot formation time (P = 0.04) and increase in α angle (P = 0.02)] and in the ex-TEM® profile [increase in maximum clot firmness (P = 0.008) and α angle (P = 0.01)]; no changes were identified in the fib-TEM® profile. In both groups, a statistically significant decrease (P = 0.007) in hematocrit was noted, whereas no statistically significant differences in platelet count and standard coagulation profile were found. In group 2, a statistically significant increase in TS values (P = 0.03) was noted at T1. ROTEM tracings indicating a hypercoagulable state were observed in 7/20 dogs at T0 (5/11 in group 1 and 2/9 in the group 2).

CONCLUSION

Our findings suggest that HES 130/0.4 administered as CRI does not cause hypocoagulability in hypoalbuminemic dogs. A trend toward hypercoagulability, probably related to the underlying diseases, was observed in group 2 at T1. Although all dogs were hyoalbuminemic, only 7/20 were hypercoagulable at T0, confirming the lack of correlation between albumin level and prothrombotic state.

Critically appraised topic on adverse food reactions of companion animals (4): can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests?

BACKGROUND

The gold standard to diagnose adverse food reactions (AFRs) in the dog and cat is currently an elimination diet with subsequent provocation trials. However, those trials are inconvenient and client compliance can be low. Our objective was to systematically review the literature to evaluate in vivo and in vitro tests used to diagnose AFR in small animals.

RESULTS

We searched three databases (CAB Abstracts, MEDLINE and Web of Science) for pertinent references on September 16, 2016. Among 71, 544 and 41 articles found in the CAB Abstract, MEDLINE and Web of Science databases, respectively, we selected 22 articles and abstracts from conference proceedings that reported data usable for evaluation of tests for AFR. Serum tests for food-specific IgE and IgG, intradermal testing with food antigens, lymphocyte proliferation tests, fecal food-specific IgE, patch, gastroscopic, and colonoscopic testing were evaluated.

CONCLUSIONS

Testing for serum food-specific IgE and IgG showed low repeatability and, in dogs, a highly variable accuracy. In cats, the accuracy of testing for food-specific IgE was low. Lymphocyte proliferation tests were more frequently positive and more accurate in animals with AFR, but, as they are more difficult to perform, they remain currently a research tool. All other reported tests were only evaluated by individual studies with small numbers of animals. Negative patch test reactions have a very high negative predictability in dogs and could enable a choice of ingredients for the elimination diet in selected patients. Gastroscopic and colonoscopic testing as well as food-specific fecal IgE or food-specific serum IgG measurements appear less useful. Currently, the best diagnostic procedure to identify AFRs in small animals remains an elimination diet with subsequent provocation trials.

Variant detection and runs of homozygosity in next generation sequencing data elucidate the genetic background of Lundehund syndrome

BACKGROUND

The Lundehund is a highly specialized breed characterized by a unique flexibility of the joints and polydactyly in all four limbs. The extremely small population size and high inbreeding has promoted a high frequency of diseased dogs affected by the Lundehund syndrome (LS), a severe gastro-enteropathic disease.

RESULTS

Comprehensive analysis of bead chip and whole-genome sequencing data for LS in the Lundehund resulted in a genome-wide association signal on CFA 34 and LS-specific runs of homozygosity (ROH) in this region. Filtering analysis for variants with predicted high or moderate effects revealed a missense mutation in LEPREL1 1.2 Mb proximal to the region of the genome-wide association, which was shown to be significantly associated with LS. LS-affected Lundehund harbored the mutant LEPREL1:g.139212C>G genotype A/A whereas all controls of other breeds showed the C/C wild type. In addition, ROH analysis for the Lundehund indicated a high enrichment of genes in potential signatures of selection affecting protein activation and immunoregulatory processes like NOD1 potentially involved in LS breed disposition.

CONCLUSIONS

Sequencing results for Lundehund specific traits reveal a potential causative mutation for LS in the neuropeptide operating gene LEPREL1 and suggests it as a precursor of the inflammatory process. Analyses of ROH regions give an insight into the genetic background of characteristic traits in the Lundehund that remain to be elucidated in the future.

Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats

BACKGROUND

To diagnose cutaneous adverse food reactions (CAFRs) in dogs and cats, dietary restriction-provocation trials are performed. Knowing the most common offending food allergens for these species would help determining the order of food challenges to optimize the time to diagnosis.

RESULTS

The search for, and review and analysis of the best evidence available as of January 16, 2015 suggests that the most likely food allergens contributing to canine CAFRs are beef, dairy products, chicken, and wheat. The most common food allergens in cats are beef, fish and chicken.

CONCLUSIONS

In dogs and cats, after a period of dietary restriction leading to the complete remission of clinical signs, food challenges to diagnose CAFR should begin with beef and dairy products, the most commonly recognized food allergens in these two species.

Urinary and faecal N-methylhistamine concentrations do not serve as markers for mast cell activation or clinical disease activity in dogs with chronic enteropathies

Background

This study sought to correlate faecal and urinary N-methylhistamine (NMH) concentrations with resting versus degranulated duodenal mast cell numbers in dogs with chronic enteropathies (CE), and investigate correlations between intestinal mast cell activation and clinical severity of disease as assessed by canine chronic enteropathy clinical activity index (CCECAI), and between urinary and faecal NMH concentrations, mast cell numbers, and histopathological scores. Twenty-eight dogs with CE were included. Duodenal biopsies were stained with haematoxylin and eosin (H&E), toluidine blue, and by immunohistochemical labelling for tryptase. Duodenal biopsies were assigned a histopathological severity score, and duodenal mast cell numbers were counted in five high-power fields after metachromatic and immunohistochemical staining. Faecal and urinary NMH concentrations were measured by gas chromatography–mass spectrometry.

Results

There was no correlation between the CCECAI and faecal or urinary NMH concentrations, mast cell numbers, or histopathological score – or between faecal or urinary NMH concentration and mast cell numbers. Post hoc analysis revealed a statistically significant difference in toluidine blue positive mast cells between two treatment groups (exclusion diet with/without metronidazole versus immunosuppression (IS)), with higher numbers among dogs not requiring IS.

Conclusion

Faecal and urinary NMH concentrations and duodenal mast cell numbers were not useful indicators of severity of disease as assessed by the CCECAI or histological evaluation. The number of duodenal mast cells was higher in dogs that did not need IS, i.e. in dogs responding to an exclusion diet (with/without metronidazole), than in dogs requiring IS. Further studies comparing the role of mast cells in dogs with different forms of CE are needed.

Glomerulopathy and mutations in NPHS1 and KIRREL2 in soft-coated Wheaten Terrier dogs

Dogs of the soft-coated wheaten terrier breed (SCWT) are predisposed to adult-onset, genetically complex, protein-losing nephropathy (average onset age = 6.3 ± 2.0 years). A genome-wide association study using 62 dogs revealed a chromosomal region containing three statistically significant SNPs (p(raw) ≤ 4.13 × 10(-8); p(genome) ≤ 0.005) when comparing DNA samples from affected and geriatric (≥14 years) unaffected SCWTs. Sequencing of candidate genes in the region revealed single nucleotide changes in each of two closely linked genes, NPHS1 and KIRREL2, which encode the slit diaphragm proteins nephrin and Neph3/filtrin, respectively. In humans, mutations in nephrin and decreased expression of Neph3 are associated with podocytopathy and protein-losing nephropathy. The base substitutions change a glycine to arginine in the fibronectin type 3 domain of nephrin and a proline to arginine in a conserved proline-rich region in Neph3. These novel mutations are not described in other species, nor were they found in 550 dogs of 105 other breeds, except in 3 dogs, including an affected Airedale terrier, homozygous for both substitutions. Risk for nephropathy is highest in dogs homozygous for the mutations (OR = 9.06; 95 % CI = 4.24-19.35). This is the first molecular characterization of an inherited podocytopathy in dogs and may serve as a model for continued studies of complex genetic and environmental interactions in glomerular disease.

Prevalence of perinuclear antineutrophilic cytoplasmic autoantibodies in serum of healthy Soft Coated Wheaten Terriers in the United Kingdom

OBJECTIVE

To estimate the prevalence of perinuclear antineutrophilic cytoplasmic autoantibodies (pANCA) in the serum of healthy Soft Coated Wheaten Terriers (SCWTs) in the United Kingdom and to identify potential risk factors and heritability patterns associated with a positive result for pANCA.

ANIMALS

188 SCWTs (age range, 18 months to 14.3 years).

PROCEDURES

Blood samples were obtained from SCWTs in various locations in England. Serum was tested for pANCA by use of an immunofluorescence assay, and total protein and albumin concentrations were determined. Pedigrees were evaluated to identify close relatives that had protein-losing enteropathy (PLE) or protein-losing nephropathy (PLN).

RESULTS

39 of 188 (20.7%) dogs, including young dogs, had positive results for pANCA. Dogs had significantly higher odds of having positive results for pANCA if they had at least 1 littermate that had PLE or PLN (odds ratio, 12.1) or if they had at least 1 full sibling from another litter known to be affected with PLE or PLN (odds ratio, 4.0). CONCLUSIONS AND CLINICAL RELEVANCE; This study revealed a high prevalence of pANCA in the serum of a representative sample of healthy SCWTs in the United Kingdom and a significant association between positive results for pANCA and a diagnosis of PLE or PLN in a sibling.

Canine breeds at high risk of developing inflammatory bowel disease in the south-eastern UK

Genetics are an important factor in the development of human inflammatory bowel disease (IBD); however, there is very little information available regarding the role of genetics in canine IBD. The purpose of this study was to gather information about which canine breeds in the south-eastern UK are at a high risk for developing IBD. Determination of such breeds may help further genetic research in this complex disease. The computer medical records at the Queen Mother Hospital for Animals, Royal Veterinary College dating from August 1, 2003 to December 31, 2009 were retrospectively searched for cases diagnosed with IBD. Five hundred and forty-six dogs with IBD were identified, representing 86 different breeds. The comparison group consisted of all dogs from these same 86 breeds without IBD admitted to the hospital during the same period that amounted to 27,463 dogs. The breeds at significantly higher risk of developing IBD compared with mixed-breed dogs consisted of weimaraner (odds ratio [OR]=3.6797, 95 per cent confidence interval [CI]=2.0167 to 6.7141, P<0.0001), rottweiler (OR=2.9697, 95 per cent CI=1.7569 to 5.0196, P<0.0001), German shepherd dog (GSD) (OR=2.4101, 95 per cent CI=1.5826 to 3.36705, P<0.0001), border collie (OR=1.9936, 95 per cent CI=1.1655 to 3.4101, P=0.0118) and boxer (OR=1.6961, 95 per cent CI=1.0441 to 2.755, P=0.0328). This study demonstrates for the first time canine breeds in the south-eastern UK that are highly susceptible to developing IBD. Identification of such breeds may allow for a more focused investigation of genetic mutations associated with canine IBD.

Pitfalls and progress in the diagnosis and management of canine inflammatory bowel disease

Inflammatory bowel disease (IBD) is the collective term for a group of chronic enteropathies characterized by persistent or recurrent gastrointestinal (GI) signs and inflammation of the GI tract. The specific steps that lead to IBD and the basis for phenotypic variation and unpredictable responses to treatment are not known. This article examines IBD in dogs, focusing on the interaction between genetic susceptibility and the enteric microenvironment (bacteria, diet), the utility of recently developed histologic criteria, the prognostic indicators, and the standardized approaches to treatment.

Laboratory tests for diagnosis of gastrointestinal and pancreatic diseases

The panel of laboratory tests available for diagnosis of gastrointestinal (GI) diseases in dogs and cats is wide, and, recently, several new tests have been developed. This article will focus on advances in laboratory tests that are available for the general practitioner for diagnosis of GI diseases. Laboratory tests for diagnosis of gastric and intestinal infectious diseases include fecal parasite screening tests, enzyme-linked immunosorbent assays for parvoviral enteritis, and some specific bacterial tests like fluorescent in situ hybridization for identification of specific bacteria attached to the intestinal epithelial cells. Serum concentrations of folate and cobalamin are markers of intestinal absorption, but are also changed in exocrine pancreatic insufficiency and intestinal bacterial overgrowth. Hypocobalaminemia is common in GI and pancreatic disease. Decreased serum trypsin-like immunoreactivity is a very sensitive and specific test for the diagnosis of exocrine pancreatic insufficiency in dogs and cats. Serum pancreatic lipase is currently the most sensitive and specific test to identify pancreatic cell damage and acute pancreatitis. However, serum canine pancreas-specific lipase is less sensitive in canine chronic pancreatitis. Increased serum trypsin-like immunoreactivity is also specific for pancreatic damage but is less sensitive. It is very likely that further studies will help to better specify the role of these new tests in the diagnosis of canine and feline pancreatic diseases.

Gas chromatography-mass spectrometry assay for determination of Ntau-methylhistamine concentration in canine urine specimens and fecal extracts

OBJECTIVE

To develop and validate a gas chromatography-mass spectrometry (GC-MS) method for determination of Ntau-methylhistamine (NMH) concentration in canine urine and fecal extracts and to assess urinary NMH concentrations in dogs with mast cell neoplasia and fecal NMH concentrations in dogs with protein-losing enteropathy.

SAMPLE POPULATION

Urine specimens were collected from 6 healthy dogs and 7 dogs with mast cell neoplasia. Fecal extracts were obtained from fecal specimens of 28 dogs with various severities of protein-losing enteropathy, as indicated by fecal concentration of alpha1-proteinase inhibitor.

PROCEDURES

NMH was extracted directly from urine, and fecal specimens were first extracted into 5 volumes of PBSS containing 1% newborn calf serum. Ntau-methylhistamine in specimens was quantified via stable isotope dilution GC-MS. The assay was validated via determination of percentage recovery of known amounts of NMH and interassay coefficients of variation. Urinary excretion of NMH was evaluated by means of NMH-to-creatinine concentration ratios.

RESULTS

Recovery of NMH in urine and fecal extracts averaged 104.6% and 104.5%, respectively. Interassay coefficients of variation ranged from 5.4% to 11.7% in urine and 12.6% to 18.1% in fecal extracts. Urinary NMH excretion was significantly increased in dogs with mast cell neoplasia, compared with that in healthy dogs. No correlation was detected between severity of protein-losing enteropathy and fecal NMH concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

This method provided a sensitive, reproducible means of measuring NMH in canine urine and fecal extracts. High urinary NMH-to-creatinine concentration ratios in dogs with mast cell neoplasia are consistent with increased histamine release in this disease.

Gastrointestinal Function

This chapter describes the normal biochemical processes of intestinal secretion, digestion, and absorption. The digestive system is composed of the gastrointestinal (GI) tract, or the alimentary canal, salivary glands, the liver, and the exocrine pancreas. The principal functions of the gastrointestinal tract are to digest and absorb ingested nutrients, and to excrete waste products of digestion. Most nutrients are ingested in a form that is either too complex for absorption or insoluble, and therefore, indigestible or incapable of being digested. Within the GI tract, much of these substances are solubilized and further degraded enzymatically to simple molecules, sufficiently small in size, and in a form that permits absorption across the mucosal epithelium. This chapter explains in detail the mechanisms of salivary secretions, compositions of saliva, and the functions of saliva. The chapter also elaborates properties of bile as well as the synthesis of bile acids. The chapter explores the pathogenesis of the important gastrointestinal diseases of domestic animals, and the biochemical basis for their diagnosis and treatment. The chapter concludes with a discussion on disturbances of gastrointestinal function such as vomition, acute diarrheas, malabsorption, bacterial overgrowth, and ulcerative colitis.

Two-dimensional grayscale ultrasound and spectral Doppler waveform evaluation of dogs with chronic enteropathies

Sonography is an important diagnostic tool to examine the gastrointestinal tract of dogs with chronic diarrhea. Two-dimensional grayscale ultrasound parameters to assess for various enteropathies primarily focus on wall thickness and layering. Mild, generalized thickening of the intestinal wall with maintenance of the wall layering is common in inflammatory bowel disease. Quantitative and semi-quantitative spectral Doppler arterial waveform analysis can be utilized for various enteropathies, including inflammatory bowel disease and food allergies. Dogs with inflammatory bowel disease have inadequate hemodynamic responses during digestion of food. Dogs with food allergies have prolonged vasodilation and lower resistive and pulsatility indices after eating allergen-inducing foods.

Food Allergy in Dogs and Cats: A Review

Food allergy (FA) is defined as "all immune-mediated reactions following food intake," in contrast with food intolerance (FI), which is non-immune-mediated. Impairment of the mucosal barrier and loss of oral tolerance are risk factors for the development of FA. Type I, III, and IV hypersensitivity reactions are the most likely immunologic mechanisms. Food allergens are (glyco-)proteins with a molecular weight from 10-70 kDa and are resistant to treatment with heat, acid, and proteases. The exact prevalence of FA in dogs and cats remains unknown. There is no breed, sex or age predilection, although some breeds are commonly affected. Before the onset of clinical signs, the animals have been fed the offending food components for at least two years, although some animals are less than a year old. FA is a non-seasonal disease with skin and/or gastrointestinal disorders. Pruritus is the main complaint and is mostly corticoid-resistant. In 20-30% of the cases, dogs and cats have concurrent allergic diseases (atopy/flea-allergic dermatitis). A reliable diagnosis can only be made with dietary elimination-challenge trials. Provocation testing is necessary for the identification of the causative food component(s). Therapy of FA consists of avoiding the offending food component(s).

The canine model of dietary hypersensitivity

IgE-mediated dietary hypersensitivity affects approximately 1% of the canine population. There are no breed associations and < or =50% of the patients are aged <1 year at presentation. The most common causative allergens are beef, chicken, milk, eggs, maize, wheat and soyabean. Affected dogs generally display cutaneous disease and 10-15% of the patients may have concurrent alimentary involvement. Diagnosis is currently based on dietary restriction followed by provocation. Procedures for the detection of serum allergen-specific IgE and IgG antibodies are widely available, but these tests correlate poorly with clinical presentation and dietary testing. Recent studies have demonstrated the allergen specificity of IgE antibodies by immunoblotting and have described blood lymphocyte proliferative responses to food allergens. In addition to investigations of spontaneously-arising dietary hypersensitivity, it has also proved possible to study this disorder experimentally. Small colonies of dogs sensitive to particular dietary proteins have been used to study clinical and serological responses to allergen challenge. Hypersensitivity has been experimentally induced in dogs of an atopic phenotype by repeated subcutaneous injection of alum-adjuvanted dietary allergen during neonatal life. These models have been used to trial a range of modified protein or hydrolysate diets. The dog provides a unique large-animal model for investigation of the immunopathogenesis of human dietary hypersensitivity. The dog is closely related genetically to man and shares environmental disease triggers with man. Spontaneously arising canine dietary hypersensitivity is a good clinical mimic of the human disease, and ability to therapeutically manipulate this adverse response in the dog might lead to benefits for human patients.

Evaluation of colonoscopic allergen provocation as a diagnostic tool in dogs with proven food hypersensitivity reactions

OBJECTIVE

To evaluate the colonoscopic allergen provocation (COLAP) test as a new tool for the diagnosis of IgE-mediated food allergy.

METHODS

Oral food challenges as well as COLAP testing were performed in a colony of nine research dogs with proven immediate-type food allergic reactions. In addition, COLAP was performed in five healthy dogs.

RESULTS

When compared with the oral challenge test, COLAP accurately determined 18 of 23 (73 per cent) positive oral challenge reactions (73 per cent) in dogs with food allergies and was negative in the healthy dogs.

CLINICAL SIGNIFICANCE

The accuracy of this new test may be higher than that for gastric sensitivity testing. Therefore, COLAP holds promise as a new test to confirm the diagnosis of suspect IgE-mediated food allergy in dogs.

Identification of allergens responsible for canine cutaneous adverse food reactions to lamb, beef and cow's milk

Lamb, beef and cow's milk are common causes of cutaneous adverse food reactions in dogs. The aim of this study was to identify the proteins responsible for cutaneous adverse reactions to these foods. Ten dogs with allergen-specific serum immunoglobulin (Ig)E to lamb, beef and cow's milk were included in the study. These dogs had been diagnosed with cutaneous adverse food reactions by convincing clinical history and food-elimination diet trials followed by challenge exposure. Sera were analysed by enzyme-linked immunosorbent assay with bovine proteins and SDS-PAGE immunoblots with lamb, beef and cow's milk extracts. All the dogs had specific IgE against bovine IgG, and it was the only protein in the cow's milk extract that bound IgE from the sera studied. In the lamb and beef extracts, the major allergens recognized by the specific IgE of most sera had molecular masses between 51 and 58 kDa, which were identified as phosphoglucomutase and the IgG heavy chain. Other IgE-binding proteins with molecular masses of 27, 31, 33, 37 and 42 kDa were also detected with some sera. Our results indicate that bovine IgG is a major allergen in cow's milk and hence it appears to be a source of cross-reactivity with beef and probably with lamb because of the high homology with ovine immunoglobulins. These results are similar to those found for meat allergy in humans. However, this is the first time that phosphoglucomutase has been identified as an important allergen involved in allergic reactions to lamb and beef.

Nutritional management of gastrointestinal disease

The gastrointestinal (GI) tract is primarily responsible for acquiring and digesting food, absorbing nutrients and water, and expelling wastes from the body as feces. A proper diet and normally functioning GI tract are integral for the delivery of nutrients, prevention of nutrient deficiencies and malnutrition, repair of damaged intestinal epithelium, restoration of normal luminal bacterial populations, promotion of normal GI motility, and maintenance of normal immune functions (eg, both tolerance and protection from pathogens). The amount of food, its form, the frequency of feeding, and the composition of diet each have important effects on GI function and may be used to help ameliorate signs of GI disease. Although both nutrients and nonnutritional components of a diet are important to GI health, they also may cause or influence the development of GI pathology (eg, antibiotic responsive diarrhea, inflammatory bowel disease, dietary intolerance, or sensitivity and/or allergy). The appropriate diet may have a profound effect on intestinal recovery and successful management of chronic or severe GI disease.

Protein-losing enteropathies

GI protein loss can result from a heterogeneous group of diseases, including lymphangiectasia, IBD, neoplasia, ulceration, intussusception, and histoplasmosis. PLE should be suspected in any hypoalbuminemic patient with no evidence of exudative protein loss, proteinuria, or HI. A minimum laboratory database for the suspected PLE patient should include a complete blood cell count, a biochemical and electrolyte profile, urinalysis (+/- urine protein:cretinine ratio), and pre- and postprandial bile acid determinations. Fecal alpha 1-PI concentrations may be used to confirm the presence of GI protein loss in cases with concurrent renal or hepatic disease. Because PLE is a syndrome and not a specific disease, the most effective therapy must be directed at the underlying cause. Multiple high-quality endoscopic biopsies are sufficient to diagnose most patients with PLE, although full-thickness biopsies are required in some cases. Patients with PLE are often clinically "fragile," and careful symptomatic therapy must be integrated with dietary and medical management strategies in most cases.

Protein-losing enteropathy associated with cystic mucoid changes in the intestinal crypts of two dogs

Two dogs were emaciated and hypoalbuminemic due to protein-losing enteropathy associated with a severe, focal, mucoid, cryptal ectasia of the duodenum and marked villus atrophy. In one case, diseased portions of the duodenum were obvious endoscopically and were limited to discrete, focal areas in the small intestine, with apparently more undiseased tissue than diseased tissue being present. The signs and lesions in one dog resolved after initiating combination dietary and pharmacological therapy.

The atopic dog as a model of peanut and tree nut food allergy

BACKGROUND

Animal models are needed that mimic human IgE-mediated peanut and tree nut allergy. Atopic dogs have been previously used in a model of food allergy to cow's milk, beef, wheat, and soy, with the demonstration of specific IgE production and positive oral challenges similar to those seen in human subjects.

OBJECTIVE

We sought to sensitize dogs to peanut, walnut, and Brazil nut and to assess whether sensitization is accompanied by clinical reactions and whether there is cross-reactivity among the different preparations.

METHODS

Eleven dogs were sensitized subcutaneously by using an established protocol with 1 microg each of peanut, English walnut, or Brazil nut protein extracts in alum first at birth and then after modified live virus vaccinations at 3, 7, and 11 weeks of age. The dogs were sensitized to other allergens, including soy and either wheat or barley. Intradermal skin tests, IgE immunoblotting to nut proteins, and oral challenges were performed with ground nut preparations.

RESULTS

At 6 months of age, the dogs' intradermal skin test responses were positive to the nut extracts. IgE immunoblotting to peanut, walnut, and Brazil nut showed strong recognition of proteins in the aqueous preparations. Each of the 4 peanut- and the 3 Brazil nut-sensitized dogs and 3 of the 4 walnut-sensitized dogs reacted on oral challenge with the corresponding primary immunogen at age 2 years. None of the peanut-sensitized dogs reacted clinically with walnut or Brazil nut challenges. One of the walnut-sensitized dogs had delayed (overnight) vomiting to Brazil nut.

CONCLUSIONS

On the basis of measurements of the mean amount of allergen eliciting a skin test response in dogs, the hierarchy of reactivity by skin testing is similar to the clinical experience in human subjects (peanut > tree nuts > wheat > soy > barley). Cross-reactivity, which was not apparent between soy and peanut or tree nuts or between peanut and tree nuts, was slight between walnut and Brazil nut. The results give further support to the dog as a model of human food allergy.

The dog as a model for food allergy

Research during the past decade has shown the dog to be an excellent model for human food allergies. Humans and dogs share many of the same allergies to foods. Furthermore, the dog model shows clinical symptoms typical of humans, that is, both experience vomiting and diarrhea. Present results suggest that the dog may provide a means to test genetically modified foods for unsuspected allergens.