Guinea pig pododermatitis (bumblefoot, sore hocks)

PODODERMATITIS can be considered a problem particularly caused by poor husbandry. It is most commonly encountered in guinea pigs housed on abrasive surfaces, especially wirefloored cages, soiled and wet bedding, and abrasive carpets.

Inflammation of the skin of the feet gives rise to the term pododermatitis. “Sore hocks” is the term most often used by guinea pig breeders. The clinical signs vary from mild (easily treated) to a severe condition involving bones and tendons that carries a very poor prognosis.

Predisposing factors

• Poorly designed bedding as mentioned above.
• Obesity or lameness in one foot leading to excess weight bearing on the other foot.
• Lack of exercise due to inadequate cage size.
• Pain due to scurvy (vitamin C deficiency) leading to immobility.
• Overgrown nails leading to further pain and immobility.
• Urinary or gastrointestinal disease with urine scald or faecal contamination.

Clinical signs

• Variable. There is no sex or age predilection.
• Usually more pronounced in front feet. The condition has been graded (after Ogilvie, 2011).
• Grade 1 – erythema on plantar surface.
• Grade 2 – erythema and swelling of feet.
• Grade 3 – erythema, swelling, ulceration and scabs.
• Grade 4 – erythema, swelling, scabs, abscesses and tendonitis.
• Grade 5 – erythema, swelling, ulceration, scabs, tendonitis and osteomyelitis.

Secondary infection most commonly occurs with Staphylococcus aureus. In more severe cases a variety of bacteria may be incriminated. These include Escherichia coli, Proteus spp, beta haemolytic Streptococci spp, Pasteurella multocida and Pseudomonas.

Diagnosis

• Diagnosis is by physical examination.
• Investigation of environmental factors and predisposing factors mentioned above.
• Culture and antibiotic sensitivity when infection is present.
• Radiography to assess degree of tendon and bone involvement.

Treatment

• In all cases investigate and treat underlying causes, supplement with vitamin C (50mg orally daily) and clip overgrown nails.
• Mild cases. Change bedding to soft, dry material such as clean hay, or padded surfaces with shredded paper. Bedding should be changed daily. Trim overgrown nails.
• More severe cases. May require gentle debridement, bandaging with up to daily changes in some cases, antibacterial treatment long term and pain control.
• Severe cases. As above but daily debridement and wound flushing is required involving daily general anaesthesia if necessary.
• Antibacterial agents. Those usually considered include enrofloxacin (5mg/ kg po bid), marbofloxacin (2-5 mg/kg po uid), or potentiated sulphonamides (30mg/kg po uid).
• Pain relief. Meloxicam (1-2mg/kg po every 24 hours) and butorphanol (0.2-2mg/kg sc every 4 hours) have been used amongst others. Informed consent may be used as few drugs are licensed for guinea pigs.

Prognosis

• Mild cases treated early with attention to husbandry problems have a fair to good prognosis.
• Osteomyelitis carries a poor prognosis, and is often irreversible. Relapse is common following treatment.
• Either amputation or euthanasia may have to be considered in severe cases.

Suggested reading

Ogilvie, Barbara. In Blackwell’s Five Minute Veterinary Consult. Small Animal. 2nd edition. 2011; John Wiley.