GASTROENTEROLOGY
to moderate disease down to insignificant disease in dogs ; and a FIBDAI score reduction from 5 to 9 down to 0 in cats . By definition a 75 % reduction in FIBDAI score is considered positive .
A well conducted food diet trial will solve both dietary hypersensitivities and food intolerances ; both of which can cause IBD symptoms . Most clinical trials see a high percentage of patients responding to diet . Canine patients with lower CIBDAI or CCECAI scores (< 5 ) and clinical signs associated with diffuse lower intestine disease are more likely to respond to dietary therapy than those with very high (> 5 ) CIBDAI or CCE- CAI scores . No such predictions can be made using the FIBDAI score in cats .
Dietary hypersensitivities are immunological reactions to dietary antigens and dietary intolerances are nonimmunological reactions to perturbations within the diet itself . For this reason some animals will respond to highly digestible , fat restricted and variable fibre diets that do not have any antigenic modifications . Usually single protein diets , containing a highly digestible novel protein source or hydrolysed diets are used . Size and structure of dietary proteins appears to affect their potential for immunoreactivity .
The role of the immune system and host microbiota in dietary hypersensitivities are being investigated . Perinuclear anti-neutrophilic cytoplasmic antibodies ( pANCA ) were significantly higher in diet responders than idiopathic IBD patients in one study but the clinical usefulness has not been established . Skin reactions are usually only seen with dietary hypersensitivity .
In the case of hydrolysed diets , potential problems include palatability issues and molecule sizes that still evoke an immune response . A complete dietary history is necessary to select the protein and carbohydrate sources in an elimination diet to suit that patient . Dietary history forms are available on the WSAVA website . Immediate , Type I and II , as well as delayed , Type IV hypersensitivities are possible with dietary antigens .
Establishing cause and effect in these cases requires strict owner compliance . Response to diet may occur within 10 to 15 days or as long as 8 to 12 weeks . Canine diet responders have an excellent prognosis but complete responders should undergo a re-challenge after 3 months because most of these patients remain asymptomatic on a fresh supply of their original type of food . The reason for this is unknown but may be related to dietary intolerances or dietary induced changes in the resident microbiome of the patient rather than dietary hypersensitivities . Unfortunately some references document a poor response to diet in cats and others warn that many initial responders may relapse and go on to require immunosuppressive therapy . For a diet trial to work the patients must be eating ; appetite stimulants may be helpful in some anorexic cases .
Dietary hypersensitivities are immunological reactions to dietary antigens and dietary intolerances are non-immunological reactions to perturbations within the diet itself .
3 . Conduct an empirical antibiotic trial in nonresponders to exclude Antibiotic Responsive Enteritis ( ARE ) Gastrointestinal dysbiosis is the new term describing unhealthy disturbances in the intestinal microbiota replacing the old term of small intestinal bacterial overgrowth ( SIBO ). There is currently no way of adequately and convincingly diagnosing bacterial dysbiosis in a clinical situation short of a therapeutic trial ; for this reason the condition is recognised as an antibiotic responsive enteropathy ( ARE ).
Antibiotics empirically used include amoxicillin , metronidazole , oxytetracyclines , sulfasalazine and tylosin . The choice of antibiotics depends on the clinician ’ s bias . Metronidazole is often advocated but potential carcinogenic side effects of long-term administration are a concern . Tylosin is well tolerated long term and may also treat occult cryptosporidium infection in some cases , it is also one of the few antibiotics besides fluoroquinolones , with some literature based evidence rationalising its use . Tylosin has activity against gram-positive and gram-negative cocci , gram-positive rods , and mycoplasma ; it is not effective against Escherichia coli and Salmonella spp .
It is therefore not used as targeted therapy against specific bacterial enteritis but rather to transiently change the intestinal microbiota possibly by promoting the growth of beneficial commensal bacteria while suppressing deleterious bacteria . Starting dose is 15 mg / kg PO BID mixed with the food or given via gelatine capsule .
Patients that do respond to antibiotics are categorised as having ARE . The use of fluoroquinolones is retained specifically for where AIEC are suspected . He duration of the antibiotic course is usually 1-2 weeks before patients are monitored for a relapse of clinical signs . Frequency and severity of relapses determine the need for continuous , intermittent regular or reactive only treatment .
The role of Helicobacter infection in IBD is not well defined . In one small study fluorescence in situ hybridisation techniques were used to diagnose the organism intraglandular in the epithelium , in the presence of gastritis . The same technique was used to show resolution after “ triple therapy ” and dietary therapy was instituted . Triple therapy is only recommended in those patients with clinical signs and histopathological evidence of gastritis in the presence of Helicobacter organisms . vet360
Issue 04 | AUGUST 2016 | 24