Short Takes: August 2010

Help for Diabetic Cats

Diabetes mellitus (DM) is a common endocrine disease in cats, and it is becoming a model for DM in humans because cats develop a form of the disease that is similar to the human type-2 diabetes mellitus. Amylin is a normal secretory product of pancreatic beta cells, and it plays an important role in controlling nutrient fluctuations. Amylin has become an established therapy along with insulin in human diabetics because it reduces post-prandial glucagon secretion and slows gastric emptying.

This study (“Amylin reduces plasma glucagon concentration in cats,” The Veterinary Journal, 2010) was the first to investigate if amylin reduces plasma glucagon levels in cats. Twelve male domestic shorthair cats were tested using an intravenous arginine test (IVAST), a meal response test (MRT) and an IV glucose response test (IVGTT). A single dose injection of a non-amyloidogenic amylin lowered plasma glucagon levels under all three test conditions. Blood insulin concentrations were also lowered following amylin administration in the IVAST and IVGTT relative to controls. The reduced post-prandial glucagon secretion found with the MRT indicates that amylin may have therapeutic potential in controlling post-prandial nutrient metabolism in diabetic cats.

This is considered one of the most significant benefits of the combination insulin-amylin treatment in human diabetics. Therefore, amylin may have a therapeutic potential in diabetic cats and be used as an adjunct to insulin in their treatment, reducing the insulin requirement to control glycemia.

Asthma and Chronic Bronchitis

Allergic asthma and chronic bronchitis are two common inflammatory conditions that affect the lower airways of cats. It has been suggested by experts that asthma in cats is allergic in nature and similar to human allergic asthma that is caused by a hypersensitivity reaction to inhaled aeroallergens. Chronic bronchitis is thought to be secondary to a previous insult (e.g., infection or inhaled irritants) that damages the airways. Because chronic asthma can damage airways, there is often an overlap between these conditions.

The study (“Evaluation of biomarkers in bronchoalveolar lavage fluid for discrimination between asthma and chronic bronchitis in cats,” American Journal of Veterinary Research, 2010) screened the bronchoalveolar lavage fluid (BALF) from a mix of 97 client-owned and research cats with naturally occurring asthma or chronic bronchitis and healthy control cats. The objective was to evaluate the BALF samples for concentrations of interleukin-4, interferin-gamma, tumor necrosis factor, and total nitric oxide metabolites as inflammatory biomarkers for discrimination between asthma and chronic bronchitis in cats.

Current diagnostic tests that attempt to differentiate these conditions include thoracic radiography and cytologic analysis of BALF. Both of these testing methods are problematic in discriminating between these diseases. The results of this particular study indicate that the inflammatory mediators investigated did not appear to be useful in differentiation between cats with naturally occurring allergic asthma and those with chronic bronchitis. The authors believe future studies should focus on validating a technique increasing the sensitivity of the currently available feline-specific cytokine assays to determine if this will overcome one possible limitation of the study.

Antimicrobial Resistance in Pets

Antibiotic resistance has been documented in E. coli isolates from human, animal and environmental resources. A growing health concern is the multidrug resistant (MDR) strains of Eshcerichia coli. There have been a number of studies that show an increase in MDR E. coli associated with infections in dogs and cats throughout the United States and Europe. In this study, 376 isolates of E. coli were collected from dogs and cats from the South, West, Northeast and Midwest regions of the United States from May to September 2005.

Fifty one percent of the isolates expressed resistance to at least one drug and 44 percent of those isolates were single drug resistant (SDR), most commonly amoxicillin. The MDR isolates (56 percent) were resistant to amoxicillin, amoxicillin-clavulanate and enrofloxacin; 18 percent were resistant to all drugs tested. The majority of the E.coli isolates were genetically and phenotypically distinct from one another.

The frequency of MDR didnt differ regionally in the United States. This study (“Antimicrobial resistance profiles and clonal relatedness of canine and feline Escherichia coli pathogens expressing multidrug resistance in the United States,” Journal of Veterinary Internal Medicine, 2010) emphasizes the need to understand that MDR isolates are not only resistant to many drugs; but the level of resistance to those drugs is very high and thus might not be overcome by increasing doses, nor combination antimicrobial therapy. Therefore, implementation of a robust surveillance program for antimicrobial resistance is recommended.