Bacterial infections may be worsening asthma in some cats according to the preliminary study of 50 asthmatic cats being undertaken by Nicki Reed, the Feline Advisory Bureau (FAB) Senior Clinical Scholar at Edinburgh University. Identifying the cause of worsening asthma may help improve treatments for up to 10,000 cats.
Feline asthma is a condition very similar to human asthma. It is estimated that as many as 1 in 100 cats in the UK may be affected by asthma, a potentially life threatening condition where the lower airways become inflamed and constricted. About 10 per cent of affected cats die of asthma or are euthanased because of treatment difficulties.
Cats can develop an allergic or hypersensitivity response to inhaled
substances such as house dust mites, dander (skin scales and debris), and pollens. In addition, physical irritants such as dust or smoke may also trigger a hypersensitivity response. This results in constriction of the airways, causing cats to cough and wheeze. Over time, the chronic inflammatory changes that accompany this condition may result in permanent airway damage, which has been traditionally treated with steroids and inhaled bronchodilators.
Nicki’s research project at Edinburgh University is looking into the incidence of a bacterial infection with a species called Mycoplasma in association with asthma in cats. Mycoplasma bacteria are often associated with lung infections in other species such as cattle, pigs and rats, but have always thought to be a ‘normal’ component of the mouth and throat in cats. However, recent work in humans has proposed that Mycoplasma pneumoniae may actually induce asthma changes in some people, or worsen the signs in previously diagnosed asthmatics.
Nicki explained: “Two veterinary papers have been published from the United States and Australia, identifying Mycoplasma species in the lungs of approximately 25 per cent of asthmatic cats. When I looked back at our records, we had not cultured Mycoplasma species from any coughing cats. This may reflect the fragility of this organism, as it does not tend to survive well outside the body, and I was certain we were missing cases of Mycoplasma infection.”
She continued with an example: “Joss had always had a history of runny eyes, but when he started sneezing and snuffling a lot, he was admitted 18 months ago for further investigations. X-rays and biopsies of the nose did not identify any abnormalities. Joss’s signs waxed and waned, but one year later, he was very snuffly and coughing. He was re-investigated as part of my study, and similar samples as previously were obtained.
This time, because he was also coughing, a lung wash was taken. Bacterial culture from the lung wash by our traditional technique was negative, but part of the sample had also been tested by a technique called PCR (polymerase chain reaction). The PCR sample showed that he did have Mycoplasma felis infection. This was accompanied by allergic rhinitis - inflammation of the nasal passages causing sniffing and sneezing.
“Mycoplasma species are unusual bacteria as they do not have cell walls, making most antibiotics ineffective in treating them. Identifying Mycoplasma infections means that appropriate antibiotics can be given. It may be sometime before the final results are published, but I hope that I can find the best method of identifying Mycoplasma infection, and increase the awareness of this bacterium in asthmatic cats,” said Nicki.
FAB supports residencies in feline medicine at UK veterinary schools to provide a referral service for owners, information for vets in practice and to assist in training for the vets and veterinary nurses of the future and provides a wealth of health information for cat owners including an information sheet on feline asthma, which is available on www.fabcats.org. For more information contact the FAB, Taeselbury, High Street, Wiltshire SP3 6LD, telephone 0870 742 2278, email email@example.com