Oct
28
2009

Cats suffering from asthma may be able to breathe easier soon, as a research team nears completion of a study to find a cure for the disease.

It has been estimated that feline asthma affects 1-5 percent of all cats, meaning that up to 4.1 million cats may suffer from asthma. Current treatments reduce clinical signs and inflammation, but do not provide a cure.

“We are working hard to develop a cure for asthma in cats,” said principal investigator, Carol Reinero, DVM, DACVIM, PhD.  “And since ‘allergy shots’ are the only available treatment with the potential to cure allergy in any species, we have developed and are testing protocols for allergic asthma in cats.” 

The three-year study is being funded by the Morris Animal Foundation. So far the team has published two manuscripts and is working on the third and last part of the study right now. Reinero said the entire study would be complete in about six months.

The team has developed a method of treatment for asthma that has produced promising results.

“Allergic asthma is caused by an abnormal immune reaction to inhaled allergens that creates damage to the airways by eliciting eosinophilic inflammation and airflow limitation,” said Reinero, an assistant professor at the University of Missouri. “Our protocol, called rush immunotherapy (RIT), is an abbreviated (rapid) form of administration of allergy shots where injections are initially given over 2 days.”

She said that while the way in which RIT alters the immune system is not well-understood, it appears to turn off the abnormal immune response to allergens.  

For the first part of the study, the group studied how cats responded to intranasally and subcutaneously administered RIT treatment. The group concluded that cats treated with both methods showed decreased eosinophilic airway inflammation, although the subcutaneous route was more consistent in resolving clinical signs. The paper, “Evaluation of subcutaneous versus mucosal (intranasal) allergen-specific rush immunotherapy in experimental feline asthma,” was published in the journal Veterinary Immunology and Immunopathology in May.

The second part of the study was to determine the best way to identify allergens that are causing clinical signs.

“There are limitations to existing allergy testing, meaning that it is likely that in choosing allergens for shots that some relevant allergens might be missed and some irrelevant allergens might be included,” Reinero said. “We compared intradermal skin testing and serum IgE testing (2 different laboratories).  We found that the ability to reliably identify IgE in serum was laboratory dependent, with one commercial laboratory identifying IgE from samples in which we had selectively destroyed it by heat inactivation. Overall, we determined that IDST is more sensitive; depending on the laboratory that assays for serum IgE, either IDST or serum IgE can be quite specific.”

That study, “Comparison of intradermal skin testing (IDST) and serum allergen-specific IgE determination in an experimental model of feline allergic asthma,” is currently in press, Reinero said, and will also be published in Veterinary Immunology and Immunopathology.

In the third and final part of the study, the researchers are looking at whether cats that are sensitized to one allergen can be effectively treated with allergy shots using a different allergen.

“Preliminary results suggest that there is ‘cross-protection,’” Reinero said. “This means that even if the veterinarian selected the ‘wrong’ allergens for immunotherapy, that there still might be a positive benefit.”

‘Exciting’ possibilities

Feline specialist Drew Weigner, DVM, DABVP, is hospital director of The Cat Doctor in Atlanta, Ga. Weigner said his practice sees several asthmatic cats per year, and a cure for the disease would be an important step.

“Asthma currently is a life-long disease which means treatment is necessary for the cats lifespan,” he said. “The current therapy (steroids and bronchodilators) can have serious side effects, and asthma can be fatal (although it rarely is in well-controlled cats) so finding a cure would be a significant advance in treating this disease.”

Weigner said he was familiar with the RIT protocol, and while it would most likely need to be performed by specialists in 24-hour facilities, its potential as a treatment is cause for excitement.

“It also may turn out to be expensive but has at least the potential to be less expensive and certainly much easier than daily medication for the rest of a cats life,” he said. “Frankly, Im quite excited about it as it is the first potential cure for asthma. It would also significantly decrease the possibility of fatal outcomes for this disease.”

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