Ulcerative pododermatitis (also known as bumblefoot or ‘sore hocks’) is a bacterial infection of the skin on the back feet and hocks of the bunny (hocks being the part of the back leg that rests on the ground when the bunny is sitting). In rabbits, the back feet are more frequently affected, whereas guinea pigs usually have problems with their front feet.
Early symptoms include fur loss on the affected limb (feet or hocks) and redness and swelling of the feet/hocks. As the disease progresses, broken skin, ulcerations and scab formation allow further progression of infection. If left untreated, the affected areas can become severely inflamed, ulcerate, and result in pus-filled sores, abscess formation and severe cellulitis. Cellulitis is a severe inflammation of the deep cellular and connective tissues. Once a deeper infection sets in, swelling of the tissues of the joints often follows, progressing to osteomyelitis (an infection of the bone marrow) and inflammation of the tendons.
Animals with pododermatitis may be reluctant to walk, or may favor one of their feet. They may display an abnormal gait or stance. These pets may become depressed, nervous and refuse to eat as a result of the debilitating pain; guinea pigs may vocalize.
There are many causes and predisposing factors for ulcerative pododermatitis:
- Exposure to rough and/or moist surfaces which keep the tissue of the foot pads soft can predispose a rabbit or guinea pig to developing sores on their feet.
- Undue pressure on the foot may can cause loss of fur and cause calluses and small abrasion, allowing bacteria to enter the tissues of the feet.
- The pressure of a large rabbit housed on a hard floor or of a guinea pig housed on a wire floor is enough to cause sore hocks. The soft tissue of the feet of the pet may become wedged between the bone of the foot and the hard surface.
- Too much friction from a rough floor surface, and exposure to constant moisture from urine or feces (especially in hot humid weather) can set the pet up for ulcerative pododermatitis , especially in animals with weakened immune systems or those that sit in soiled litter. Obese pets, or pets which get too little exercise are at increased risk due to the increased amount of pressure placed on the foot surface, and/or the amount of time sitting in one place. Interestingly, rabbits that thump their feet excessively are also at an increased risk of developing skin problems with the surface of the foot pad and hock.
- Certain breeds of rabbits (notably Rex rabbits) are more prone to loss of hair on the foot.
- Guinea pigs who receive too little vitamin C in their diet will also be more prone to bumblefoot.
In addition, some rabbits or guinea pigs can develop ulcerative pododermatitis secondary to another (primary) bacterial infection, such as that caused by Staph. aureus, Pasteurella or E coli.
Next: prevention and treatment of bumblefoot
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