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Bumblefoot (Ulcerative Pododermatitis)

From TheRatGuide.com

Definition

The inflammation and infection of the plantar surface and connective tissue of the foot/feet.

Clinical Signs May Include

Raised, reddened tissue on the sole of one or both hind feet
Open sore or ulceration on the sole of one or both hind feet
Intermittent bleeding
Presence of pus if abscessed

Cause

Ulcerative pododermatitis is a chronic granulomatous condition resulting from ulcerative lesions, and necrosis of the tissue on the plantar or heel portion of the feet.

The lesions, often resulting from abraded tissue or pressure, begin as small, reddish, raised areas of keratinized growth that develop crusts/scabs. Intermittent bleeding results when these areas filled with blood break open, drain, and then close. If the area is abscessed, then along with the blood, pus fills the area and drains upon rupture. This cycle is repeated when continuous pressure is placed on these raised, filled areas of tissue.

Secondary bacterial and fungal infections often develop when the abraded or ulcerated areas on the feet are exposed to normal skin flora, soiled bedding, or cages with accumulated urine-soaked feces. If the wounds are left untreated, or if treatment is not effective, infection can spread to the lymphatic system, to the bone causing osteomyelitis, or travel to the blood causing bacteremia and sepsis. If there is secondary infection Staphylococcus aureus is the bacteria most often cultured; however, other pathogens can be involved.

Factors that may play a part in the development of ulcerative pododermatitis are: rats that are overweight with or without hind limb neuropathies which places continued or excessive pressure on the feet, trauma, or minute abrasions from rough or irregular cage flooring, or rats having a genetic predisposition. It is also thought that the use of pine or cedar shavings used to cover cage flooring may play a part.

Although ulcerations of this sort, if caught early, can be cured, the treatment may require weeks to months of diligent care. It is also important to try to determine the underlying reason and correct it, or the condition is likely to return.

In cases where conservative treatment has been unsuccessful, or when surgical debridement has failed in more advanced conditions, amputation of the foot may be required. For cases such as these the prognosis is guarded.

Overall it is by far easier to try and prevent ulcerative pododermatitis than to affect a cure.

Figures

Case Histories of Ulcerative Pododermatitis

Fig. 1 Ulcerative pododermatitis of both feet.
Fig. 2 Ulcerative pododermatitis.
Fig. 3 Ulcerative pododermatitis and Blu-Kote application.
Fig. 4 Ulcerative pododermatitis (Snowy).

Figure 1

Figure 1: Ulcerative pododermatitis

Commonly referred to as bumblefoot, this starts as an ulcer which can then become infected with Staph aureus. The ulceration is typically the result of repeated pressure/trauma primarily to the sole of the foot. Though there are multiple factors, one of the more commonly recognized reasons is minute lacerations from roughly made wire floored cages.

Figures 2A and 2B: Pododermatitis

These were acute cases with no previous warning - the first case I assumed was an injury. It just appeared as severe swelling in a 14-month-old male. We did an X-ray and found no fracture. There was significant edema. We treated with an injection of dexamethasone at the emergency practice I work at. I brought him to my regular vet (where I now work) and she prescribed a heavy dose of prednisone, trimethoprim-sulfa, and oral Torbugesic. The dexamethasone had done nothing by itself, and he was dragging the foot, which was about three times its normal size. It took two days for the foot to reduce to just slightly over normal size, though it remained pink for another day.

A few months later I had another boy (in the pic), Lance, come down with the same condition. His foot swelled and was red all the way up his leg - much further than Marius’, which was contained to his foot. I treated immediately with the prednisone, Torbugesic, and trimethoprim-sulfa. His took a little longer - three days to improve. Both cases cleared up completely by the end of the 10-day course of trimethoprim-sulfa. I had one another case - a female. She had a slight case of bumblefoot that I believe developed into the same infection. I do believe these infections are related to bumblefoot, as they have all been in overweight rats on solid-bottom floors. Her swelling cleared up, but she had a chronic bumble on that foot that I often had to pressure bandage because of bleeding.

Note the ulcerations on the soles of both feet.

Figure 2A

Tiny area of ulceration can be seen on plantar portion of right foot.

Figure 2B

Advancing inflammation and infection.

Figure 3A

Shows developing bumblefoot to both hind feet.

Figure 3B

Shows application of Blu-Kote, which is a drying agent. It is advisable to lay a towel down, and to wear an old shirt prior to application as this agent does stain when first applied.

Figures 3A through 3D: Bumblefoot

Stu!, a male rat, was 14.5 months old at the time the bumbles to his feet were first noticed on 11/15/02. The month prior to this his heels seemed slightly reddened, but at the time we decided we were imagining it having never actually seen bumblefoot up close(I thought it would look more like the big blisters on the RMCA article).

Stu!’s cage has a solid bottom (lined with CareFRESH litter), a solid ramp, and shelf, although he likes to lounge on top of his wire cage. Until the bumbles were noticeable, he always had a washcloth or piece of fleece to lie on in his igloo “penthouse”, however since the presence of the bumbles, a solid layer of cardboard, a tea towel, and a piece of fleece for him has been placed on the top 2/3 of the cage, leaving only a few rungs exposed for him to climb up and down on. Unfortunately, the bumble on his left foot became increasingly worse, even thought we had been checking his feet daily. It was at this point that we sent for and received the Blu-Kote through the RMCA (when we couldn’t find it locally), and applied it to both feet.

The first three of four photos are taken of Stu!’s third application of Blu-Kote. The fouth photo taken in 2/03 shows no increase in the bumble to the left heel, as well as signs of improvement to the right foot.

It is worth mentioning that none of our other rats, which are all related to him, have ever had any signs of bumbles. His Mother, Aunt, and Sisters live in a similar type cage, and they all love to climb. It is thought that one of the reason’s for Stu! having developed bumble foot is his much larger size and tendency to overweight than his family members.

The photo in Figure 3D shows application of Blu-Kote continues, along with the topical antibiotic Neosporin. The application of both these agents have been reduced to once a day, and as can be seen here, the bumble to the right foot is noticeably improved.

*Update 5/23/03:*
Bumbles not completely resolved, started on amoxicillin, a systemic broad spectrum antibiotic.

Stu! stayed on the antibiotics until his passing from an unrelated condition several months later. Though the bumbles never healed completely, they had shrunk noticeably while he was on the oral medication and looked like in time, they would have vanished entirely.

Case history and photo courtesy of Kristin J. Johnson The Wererat’s Lair

Figure 3C

Shows feet after Blu-Kote has dried.

Figure 3D

Diagnostics

Assess for ulceration, bleeding, necrosis and infection.

Obtain a history for causative factors.

Culture and Sensitivity.

Treatment

Recommended treatment includes: cleaning lesions with an antiseptic solution, the application of a topical antibiotic ointment, as well as including an oral broad-spectrum antibiotic.

The following are various treatment options:

Clean ulcerations using an antiseptic soap and water, or a 1% dilute solution of chlorhexiderm/chlorhexidine flush. Apply Blu-Kote spray (wound medication for horses found in feed stores) to wound area at least two times a day, or more if the feet become soiled. An alternative to Blu-Kote is Granulex spray.
Clean ulcerations using an antiseptic soap and water, or a 1% dilute solution of chlorhexiderm/chlorhexidine flush. Apply Zymox (ear cleanser) otic solution to ulcerative areas, with or without hydrocortisone, depending on inflammation present. Give broad-spectrum antibiotic Clavamox (amoxicillin-clavulanate) orally.
Cleaning the ulceration with a Betadine solution (dilute to color of weak tea), and then applying a Betadine ointment at least three times a day.
Cleaning of the ulceration and application of Polysporin or Bacitracin topical antibiotic ointment along with Blu-Kote application if bumbles are persistent.
Cleaning ulceration with antiseptic solution and apply DILUTED tea tree oil to the bumbles several times each day.

(Note: tea tree oil contains phenol-containing essential oil. Active ingredients are cyclic terpenes which are similar in structure and action to turpentine. There have been reports of toxicity after consuming tea tree oil by mouth. There has also been reports that when applied to the skin, tea tree oil can be mildly irritating, resulting in the development of allergic contact dermatitis. If choosing to use this agent be sure to adequately dilute the tea tree oil, and do not let the rat lick the area).
Cleaning the ulceration with antiseptic solution and apply diluted Grapefruit Seed Extract (found in Health Food Stores) to the ulceration several times a day. (Recommended by Virginia Simpson, RMCA member.)

Alternative Meds: Give Grapefruit Seed Extract (GSE) orally.

Use 1 drop per 10 pound of rat. Mix as 1 drop GSE for 9 drops fruit juice per dropper in a dropper bottle so each drop of juice contains 1/10th of a drop of GSE. Give 1 to 2 drops on a piece of bread twice daily. Store in refrigerator.

Refer to Nutriteam:Pets and Grapefruit Extract for more information and ordering.

In persistent, difficult to treat bumbles, where previous treatments have not achieved desired results the following solution may be mixed, by or per order of the veterinarian, for application once or twice a day to the bumble as directed.

Solution mixture:

1cc Azium (aka Dexamethasone)

2cc Gentocin from a 100mg bottle (aka gentamicin)

1/2 oz. Propylene Glycol

1/2 oz. DMSO

In the event an oral medication would be required any of the following may be prescribed by the veterinarian. Dosages can be obtained by reviewing the Rat Medication Guide:

Trimethoprim/sulfa
Enrofloxacin
Clavamox
Flagyl (where anaerobic bacterial infections is suspected or confirmed)
Ketoconazole (where fungal infection is suspected or confirmed)

Treatment and the healing of bumbles may take up to several weeks, or be persistent throughout the life of the rat. What is important here is that the treatment chosen, if showing signs of effectiveness, should be continued until the ulceration is healed. If signs indicate that the ulceration is not improving over time, or in the event there are signs of further infection both locally or systemically, the treatment needs to be reevaluated and changed.

In any case a veterinarian should be consulted, especially if condition worsens or fails to resolve with any prescribed treatment.

It is also important to note that while debridement may be an option in severe cases of ulceration where necrotic tissue or abscess is present, or where more conservative treatment has been unsuccessful, it often poses greater difficulty due to the fact that rats normally do not have a great deal of tissue or adequate blood supply on that portion of the foot.

In cases that are very severe where surgical intervention may be required, there is the risk that the rat will require amputation of the foot. (See article BumbleFoot by Mary Ann Isaksen, RMCA Founder.)

Medication that may be used for pain control when surgical intervention is required:

For severe pain or first 24 hours post-op: Buprenex (buprenorphine), or Torbugesic (butorphanol).
For mild to moderate pain: Banamine (flunixin meglumine), Metacam (meloxicam), or carprofen. Do not use if a corticosteroid has already been prescribed.

Nursing Care

Use chlorhexiderm, or chlorhexidine, at a concentration of not greater than 1%. Diluted solution should appear lighter than a robin’s egg blue.
When applying Blu-kote, allow time for the application to dry as much as possible (or as rat allows). This ointment does tend to be messy and will stain.
Maintain cleansing treatment and ointment applications until ulcerations are healed.
If antibiotics are given remember to include Bene-Bac or yogurt with live active cultures in order to prevent normal gut flora from being destroyed by the antibiotics.
During treatment, provide clean bedding daily such as felt, soft t-shirt type material, or ink-free paper towels. Avoid litter-type bedding during treatment to prevent contamination or infection if wounds are present, and to prevent the litter from sticking to medicated areas of the foot or feet.
Monitor for extent of bleeding in order to prevent anemia.
Maintain healthy diet and reduce percentage of fat intake. Reduce number of treats if rat is overweight.
If no progress in healing is seen after several weeks, or if rat shows signs of further ulceration, abscess, foul smelling pus, or general apathy, contact veterinarian.

Outcome

Ulcerations heal.
Ulcerations do not develop into septic condition.
Healthy weight is obtained

Prevention

Do a head to toe physical assessment of your rat weekly, paying attention to the soles of feet. Clean and treat any cuts or abrasions found to prevent infection.
Maintain clean cage environment.
Cover portions of, or any irregular areas in, wire-floored cages. Examples of coverings can include vinyl floor covering, plastic needlepoint canvas, carpeting, towels, self stick tiles, plastic place-mats, fiberboard, and Plexiglas.
Use of litter boxes will help to prevent continued walking on either rough or soiled litter.

References

Atwal, R. (2003). In vitro antimicrobial activity assessment of Zymox otic solution against a broad range of microbial organisms. The International Journal of Applied Research in Veterinary Medicine, 1(3). Retrieved November 21, 2008, from http://www.jarvm.com/articles/Vol1Iss3/Atwal.htm

Retired Rodents - they're in the retirement category because they're

Figure 1: Ulcerative pododermatitis

Figures 2A and 2B: Pododermatitis

Figures 3A through 3D: Bumblefoot

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