These particular lumps are caused by a bacterium called Streptococcus zooepidemicus infecting guinea pigs.

Of course guinea pigs may get swellings or lumps on any area of the body, but the condition called "lumps" usually causes swellings around the head and neck.

The bacteria, having been introduced to the cavy by a carrier animal (usually a bought in cavy), gains access to the body via small abrasions in the mouth. Vitamin C deficiency will predispose to infection as it retards wound healing. An abscess forms at the site of entry and these may swell up to golf ball size. Abscesses may form in any organ, however head and neck are most common. If the bacteria is introduced into a group of cavies which has never had contact with it before, an epidemic may occur with cavy deaths. Later on surviving cavies will show the classical "lumps" in the neck.


  •  good husbandry ie:
    • fresh greens every day for Vitamin C
    • avoid overcrowding
    • clean bedding to avoid ammonia build up
    • good fresh hay free of thistles and mould
  • avoid mixing bought in stock with resident cavies straight away
  • regularly check cavies for neck lumps and treat any affected seperately



  • large abscesses may need to be lanced and drained. Sometimes sedation is needed for this. Valium 5mg/kg intraperitoneally given by a vet works well. Keep the area clean and free of flies whil it heals. Antibiotics will be needed.
  • small abscesses less than 1cm diameter may respond to antibiotics alone. Cephalexine (Rilexine, Ceporex) seems to be relatively safe in guinea pigs. The dose is 50-100mg/kg daily by injection for 5-10 days. All antibiotic injections are restricted medicines. This means that your vet will need to see your caviary and /or at least some affected cavies, before prescribing antibiotics. Also as the antibiotic must be given by injection, either your vet must give the injections or instruct you in the proper way to do this.

An ounce of prevention is worth (and is cheaper than) a ton of cure.


Dawn Mills