Abscesses in cats

Most owners of a cat or cats are familiar with cat bite abscesses. Affected cats may seem off colour or unwell. There may be a detectable lump or discharge evident. 

Cats are very territorial animals and as a result often get into fights. Unfortunately the population of bacteria that a cat carries in it's mouth is quite unpleasant and more often than not these bacteria are transferred into the wounds of the victim where they in turn set up the abscess. The bacteria multiply in the tissue and the body responds by producing inflammation in the area and trying to wall off the infection. The pus forms inside the walled off area and usually bursts out once it is under pressure. 

If you suspect that your cat has been bitten or has an abscess you should contact your veterinary surgeon. Early treatment of a bite can prevent the abscess from forming. Often owners are unaware of a bite and the first they know of the injury is when an abscess has formed. If the abscess is not draining your veterinary surgeon will usually make a hole for the pus to escape from. Your cat will require antibiotics and often some pain killer for a short time. The draining area whether created naturally or by your vet should be kept clean. You should encourage the area to stay open for drainage for a few days as if the exit seals too soon there is a risk of more pus forming at the site before the antibiotics have done their job. 

It can be hard to prevent these problems in the first place. Un-neutered male (Tom) cats are more likely to fight than other cats. If you have an un-neutered Tom you should consider having him castrated both for his benefit and for that of the local cats. Keeping your cat indoors at night may also help to reduce the problem as most cats are more active at night than during the day, and therefore more fights occur overnight than in daylight hours.

There is also the risk of transmission of feline leukaemia ( FeLV) or feline immunodeficiency virus ( FIV) from a carrier cat to their bitten victim.

As Staphylococcus aureus bacteria is a common cause, an anti-staphylococcus antibiotic such as flucloxacillin or dicloxacillin is used. With the emergence of community-acquired methicillin-resistant staphylococcus aureus MRSA, these traditional antibiotics may be ineffective; alternative antibiotics effective against community-acquired MRSA often include clindamycin, trimethoprim-sulfamethoxazole, and doxycycline. (However, if cellulitis rather than abscess, consideration should be given to possibility of strep species as cause that are still sensitive to traditional anti-staphylococcus agents such as dicloxacillin or cephalexin.) It is important to note that antibiotic therapy alone without surgical drainage of the abscess is seldom effective due to antibiotics often being unable to get into the abscess and their ineffectiveness at low pH levels. Whilst most medical texts advocate surgical incision some medical doctors will treat small abscesses conservatively with antibiotics.

Recurrent infections

Recurrent abscesses are often caused by community-acquired MRSA. While resistant to most beta lactam antibiotics commonly used for skin infections, it remains sensitive to alternative antibiotics, e.g., clindamycin (Cleocin), trimethoprim-sulfamethoxazole (Bactrim), and doxycycline (unlike hospital-acquired MRSA that may only be sensitive to vancomycin IV).

To prevent recurrent infections due to Staphylococcus, consider the following measures:

• Topical mupirocin applied to the nares. In this randomized controlled trial, patients used nasal mupirocin twice daily 5 days a month for 1 year.
• Chlorhexidine baths, ^[8] In a randomized controlled trial, nasal recolonization with S. aureus occurred at 12 weeks in 24% of nursing home residents receiving mupirocin ointment alone (6/25) and in 15% of residents receiving mupirocin ointment plus chlorhexidine baths daily for the first three days of mupirocin treatment (4/27). Although these results did not reach statistical significance, the baths are an easy treatment.