A Novel Therapeutic Approach for the Treatment of White Line Disease Using a Two-Part Chlorine Dioxide Gel

By Dr. Walter L. Kreeger

At the 2005 American Farriers Association annual convention, the research committee concluded its first research competition. The aim of the competition was to increase the knowledge base about the equine hoof, and demonstrate that farriers are part of the group of veterinarians and animal scientists that research the hoof. Nine research abstracts were submitted, and the topics ranged from therapy for laminitis to equine behavior. The quality of the abstracts was high, and there is no doubt that farriers can contribute objective, systematic information to the knowledge base of the equine hoof. The winner of this year’s competition was Dr. Walter Kreeger, a farrier, educator and researcher from Arkansas. His abstract contained the elements of good research: an important and interesting problem, with quantitative data obtained in an objective way. Walter agreed to have his research published in Professional Farrier, and his work is presented below.
         
Richard B. Evans, PhD
Iowa State University
AFA Equine Research Committee

Walter L. Kreeger grew up in Germany. He is a retired army officer and holds a master of fine arts in translation and a doctorate in university administration. Presently, he works as a translator and consultant in the United States and abroad when he is not shoeing horses. Dr. Kreeger, the farriery instructor at Northwest Technical Institute, in Springdale, Arkansas, is bilingual and does much of his farriery research in German.
His publications span from farrier articles to the translation of an Austrian novel, Refractions, with Ariadne Press at University of California at Riverside in 1994, and co-authored Five Stars for Managers: Strategy Concepts in Business published by Purdue University Press in 2001. He lives on a mountain top in Arkansas where he and his wife raise Arabian horses.

ABSTRACT:

White line disease is a common problem in horses that is seen in all age groups without sex or breed predilection. The disease occurs in all parts of the United States (and the world) but is more prevalent in hot, humid areas. Some of the factors contributing to separation of the hoof/sole junction are unbalanced feet (i.e., improper trimming), excessive moisture, and an acute hoof angle such as seen in long toe/low heel conformation, hoof cracks, chronic infection or abscess formation.

            Nine horses taken from pasture, dry lot, and stalled habitats were examined for the purpose of treatment for white line disease. The individual horses presented total hoof lesion volumes from 6.73 cm³ to 1.00 cm³. Conventional treatments involve radical removal of affected hoof tissue resulting in hoof mutilation and usually transportation to a clinic; therefore, the goal of the study was to find a method of treatment that can be done in the field by the farrier during the normal shoeing cycle and still have some positive results in the reduction of white line disease.

            All horses were placed on a six-week shoeing schedule. Old shoes were removed carefully so as to not provide false measurements. The feet were examined with the aid of a hoof pick and the frog and sole were trimmed back as necessary. Hoof wall was nipped to sole level and then leveled with the rasp. Measurements for depth, width, and length of infected area were taken and recorded for each animal. Ciderm EQ (sold under the Trade name White Lightning Gel)*, a two-part gel that when mixed liberates free chlorine dioxide gas. The two components are mixed just prior to use whereupon the gas is generated and is active for about six hours. The horses were shod after a liberal application of Ciderm EQ (sold under the Trade name White Lightning Gel) (sold under the Trade name White Lightning Gel) into the lesion area.

This process was repeated twice more at six week intervals, and the measurements were recorded and noted.

            The results of this study suggest that the use of a chlorine dioxide producing gel is a simple, inexpensive treatment that can be used in conjunction with adequate shoeing to optimize the recovery interval in white line disease. This treatment appears to be as or more effective than radical hoof mutilation; however, additional studies are necessary before such a claim can be fully substantiated.

INTRODUCTION:

White line disease is the deterioration of the inner part of the hoof wall. This condition is also referred to as seedy toe, hollow hoof, and/or onychomycosis. The “white line” is that distinct soft and non-pigmented inner layer of the hoof wall between the cornified hoof wall and the underlying bone. When viewed from the ground surface of the foot, it is that thin area, perhaps one eighth of an inch thick or in some cases slightly thicker, where the sole joins the hoof wall. As farriers know it, it is that area into which the nails are driven.

            White line disease is a common problem in horses that is seen in all age groups without sex or breed predilection. The disease occurs in all parts of the United States (and the world) but is more prevalent in hot, humid areas. In the early stages of the disease, the only noticeable change on the ground surface of the foot is a small cheesy or powdery area near the sole and hoof wall junction.  The disease itself appears to cause little or no problem for the animal until it becomes chronic or reaches an advanced stage. The first sign seems to be a small, hollow area just outside the white line in the stratum medium of the hoof wall itself. The ground surface of the hoof wall will have a slight separation of the stratum internum and stratum medium creating a subungual space that gathers dirt and keratin debris and provides a good medium for opportunistic organisms to propagate. It may appear in the quarters of the hoof or the toe or even the heel area; however, if the heel area is affected, then spreading of the disease does not seem to be as rapidly as when the quarters have been invaded. As the disease progresses, the hoof wall will become rotten, shelly, and predisposed to cracking and will not hold a shoe for any length of time. With proper care, prognosis is usually good; however, there can ultimately be a separation of the hoof/sole junction causing severe lameness.

            Some of the factors contributing to separation of the hoof/sole junction are unbalanced feet (i.e., improper trimming), excessive moisture, and an acute hoof angle such as seen in long toe/low heel conformation, hoof cracks, chronic infection or abscess formation.

            Michael Wildenstein’s article in American Farriers Journal4, provides evidence that white line disease is attributable in part to a fungal infection. Mr. Wildenstein’s method of exposing the fungus to chlorine dioxide by wrapping an air-tight containment over the hoof such as an old intravenous fluid bag cannot be easily carried out by a farrier in the field. The animal must be transported to a clinic or appropriate treatment facility for this type of procedure. More conventional treatments have involved radical removal of affected hoof tissue resulting in hoof mutilation. It is believed that this radical tissue removal also eliminates the moist, anaerobic environment that is conducive to fungal or anaerobic bacterial growth.  This type of treatment is usually incapacitating and renders the horse unable to perform.  Prolonged and extensive follow up treatments such as wrapping and perhaps even soaking are also necessary. It would be advantageous to develop a method of treatment that can be done in the field by the farrier during the normal shoeing cycle and still have some positive results in the reduction of white line disease.
Chlorine dioxide is a gas and is also a small molecule that quickly penetrates both tissue and bacteria ¹. According to Frontier Pharmaceutical, Inc., manufacturer of Ciderm EQ (sold under the Trade name White Lightning Gel), “Ciderm liquids and gels are probably the fastest known disinfectants killing all common pathogens within one minute, in vitro”¹. For diseases of the hoof, Ciderm EQ (sold under the Trade name White Lightning Gel) is conveniently packaged in a small twin syringe along with a small plastic tip that mixes and dispenses the two-parts of the disinfectant gel in one operation.

 

 

The tip permits dispensing the gel into the narrow lesions in the hoof. Ciderm EQ (sold under the Trade name White Lightning Gel) is a two-part system that when mixed liberates free chlorine dioxide gas.  The two components are mixed just prior to use whereupon the gas is immediately generated and is active for about six hours.

            Microorganisms evaluated by Kenyon, A. J. et al include bacteria, viruses, yeast, amoeba, as well as cysts and spores. In addition to speed and broad-spectrum activity, chlorine dioxide is anti-inflammatory by way of oxidizing free radicals and cytokines, chemicals the body releases in response to a wound or infection. Deactivation of these molecules reduces scarring, pain and irritation (², ³).

            The goal of the following study was to develop a method of treatment for white line disease that can be done in the field by the farrier during the normal shoeing cycle and still have some positive results in the reduction of white line disease.

 

MATERIALS AND METHOD:

The nine animals were selected for study due to the presence of white line disease determined by visual inspection.  The presence of white line disease was established while dressing the palmar and plantar surfaces of the feet and finding a separation of the stratum internum and stratum medium wherein a mealy substance was detected. After cleaning out the separations, the hoof lesions were measured using a digital electronic caliper to determine the width, length, and depth of the affected area. As most lesions were irregularly shaped, dimensional measurements were recorded as averages of multiple observations.  For the purposes of comparison, the lesion volumes of all feet were added together to give a sum total lesion volume per horse.

The animals ranged from 4 years to 18 years of age of which 5 were geldings and 4 mares. All horses were of the Quarter Horse breed. Four of the animals were maintained in dry lots with free-choice mixed grass hay and two daily rations of sweet grain of approximately 3 lbs. per horse per feeding. Purina horse minerals were made available free-choice. A run-in shelter with good drainage toward the front was available.

Two animals were stalled on rubber mats over concrete with approximately 3 inches of mixed wood shavings. Stalls were cleaned daily; however, occasional morning inspections revealed rather wet shavings. The horses were maintained on approximately 6 lbs. of sweet grain with roughly 6 flakes of Bermuda hay divided into two feedings. No additional supplements were offered. The horses were turned out into individual runs during the day and stalled during the night. The runs were not well maintained.

Three horses were maintained on nearly twenty acres of fescue grass with interspersed patches of orchard grass. The pasture contained a creek that formed some marshy areas.

All horses were placed on a six-week shoeing schedule. Old shoes were removed carefully so as to not provide false measurements. The feet were examined with the aid of a hoof pick and the frog and sole were trimmed back as necessary. Hoof wall was nipped to sole level and then leveled with the rasp. Measurements for depth, width, and length of infected area were taken and recorded for each animal. St. Croix Eventer shoes without clips were used on all feet to provide more surface area and protection over the infected area. The shoes were shaped cold and readied for each foot. Ciderm EQ (sold under the Trade name White Lightning Gel)’s mixing tip was installed and the mixed gel was liberally applied into and over the infected area (two-part gel and mixing tip enough to treat four feet costs about $15.00). The shoes were then nailed on with Australian City 5 Slims making certain that sufficient gel covered all of infected areas to include the entire white line. The hoofs were then coated with Hawthorne Sole Pack’s S-Pack solution in order to seal any old and new nail holes and to aid in securing the clinches (approximate cost for four feet is $5.75).

After six weeks, the procedure of cleaning, trimming, leveling, and measuring was repeated. Measurements were recorded and improvement of infected areas was noted. The old shoes were cleaned and checked for fit, reshaped where necessary, and reapplied over another liberal application of Ciderm EQ (sold under the Trade name White Lightning Gel) and the nail holes were again sealed with Hawthorne’s S-Pack solution.

As another six week period passed, shoes were again pulled, feet examined with a hoof pick and the sole and frog were trimmed back as necessary. Hoof wall was nipped to sole level and then leveled with the rasp. Measurements for depth, width, and length of infected area were taken and recorded for each animal. New St.Croix Eventer shoes without clips were used on all feet to again provide more surface area and protection over the infected area. The shoes were shaped cold and readied for each foot. Ciderm EQ (sold under the Trade name White Lightning Gel)’s mixing tip was installed and the mixed gel was liberally applied into and over the infected area. The shoes were then again nailed on with Australian City 5 Slims making certain that sufficient gel covered all the infected areas to include the entire white line. The hoofs were then again coated with Hawthorne Sole Pack’s S-Pack solution in order to seal any old and new nail holes and to aid in securing the clinches.

 


DISCUSSION:

            Treatment for white line disease has usually involved radical hoof trimming in conjunction with some sort of topical antimicrobial therapy to reduce the incidence of secondary infections. Although these methods have seen variable success, they often result in secondary complications or a noticeable degree of loss of function. The treatment method described in this study uses a more conventional shoeing technique in conjunction with chlorine dioxide as an antimicrobial agent. Chlorine dioxide gas, generated from a two-part gel, should be an effective antimicrobial agent in this circumstance due to its broad antibacterial and antifungal spectrum in addition to its ability to access small recesses that may harbor such organisms and be protected from other topical treatments. The result of this study suggests that the use of chlorine dioxide producing gel is an effective adjunct in the treatment of white line disease. The use of chlorine dioxide gel in conjunction with timely and proper shoeing techniques resulted in substantial improvement in white line disease lesion measurements by 12 weeks post treatment.

            In the horses selected for use in this study, white line disease was confirmed by the presence of characteristic abnormalities consisting of a hollow area just outside the white line in the stratum medium of the hoof wall. A separation of the stratum internum and stratum medium revealed the formation of a subungual space that gathers dirt and keratin debris. Regardless of housing environment, the front feet were usually more severely affected than the hinds,      which is also typical for the disease.

            A principle differentiating feature among the horses used in this study was the exposure or lack of exposure to ground moisture due to their differing housing environments.  Housing environments could be correlated with disease severity at the beginning of the study. The pastured horses were likely exposed to the highest level of environmental moisture due to the presence of a creek and swamp-like conditions. This is somewhat unusual, because the disease is not reported as often in pastured horses (horses turned out and exposed to “nature’s natural environment.”) The stall situation probably had the next highest amount of average moisture and horses in dry lot situations had the least amount of exposure to environmental moisture.  It has been suggested that fungal infections may play a role in the development of white line disease4 and as higher moisture levels are conducive to fungal growth, it is likely that the presence of a greater environmental fungus biomass may have contributed to the increased disease severity in the horses exposed to the more moist environments.   Horses that started out with the highest lesion volumes also had the greatest percentage reduction in lesion volumes at the end of the 12 week study period.  So it seems that even though different environments correlated with disease severity initially, the environment did not affect the response to therapy. As a side note, this study also demonstrated that horses are susceptible to the development of white line disease regardless of their type of housing environment.

            The results of this study do however suggest that the use of a chlorine dioxide producing gel is a simple, inexpensive treatment that can be used in conjunction with adequate shoeing to optimize the recovery interval in white line disease. Although the positive results seen in these animals occurred with chlorine dioxide and concurrent shoeing, it can not be definitely determined if one of these factors had a greater effect than the other on improvement.

The cost of the double syringe of gels and mixing tip from Frontier Pharmaceutical, Inc. is about $15.00 and in most cases is sufficient to treat all four feet just prior to shoeing. This treatment appears to be as or more effective than radical hoof mutilation (removal of hoof wall) and has a shorter recovery interval; however, additional controlled studies are necessary to more clearly define the true impact of the chlorine dioxide before such a claim can be fully substantiated.

RESULTS:

The results of hoof lesion measurements at the beginning of the treatment and at two subsequent six week intervals are provided in Table 1 and summarized in Table 2. The horses boarded on pasture had greater initial hoof lesion volumes than the horses boarded in stalls, and those animals kept in a dry-lot situation had the lowest hoof lesion volumes.
The most dramatic reduction of hoof lesion volume occurred in stalled Horse #1 and dry lot Horse #IX, and the least improvement was shown by two pastured horses.

            Of the two horses stalled during the night, Horse # I presented during initial examination (also referred to as Week 0) with total hoof lesion volume in all four feet of 3.07 cm³. Horse # II presented with 3.94 cm³ of hoof lesion volume at the same Week 0 examination. The horses were treated and shod and re-examined six weeks later. Measurements taken at Week 6 and again during Week 12 where Horse # I revealed a total % lesion volume reduction of 86.51% and Horse # II a reduction of 82.40%. The data for the stalled horses is also presented in a graph entitled Hoof Lesion Volume of Stalled Horses.

            Four dry lot horses were examined and treated during this study. Horse # III presented at Week 0 with 1.14 cm³of hoof lesion volume, Horse # V with 1.04 cm³, Horse # VIII with 2.22 cm³, and Horse # IX with 1.80 cm³. After two regular shoeing cycles, Horse #3 revealed 68.55% total % reduction in lesion volume, Horse #5 with 74.25%, Horse #VIII with 82.15%, and Horse #IX with 83.47%. It is notable that the right hind on Horse #V and Horse #VIII revealed a negligible amount of lesions at Week 12. The data for the dry lot horses is also presented in a graph entitled Hoof Lesion Volume of Dry Lot Horses.

            The remaining horses involved in the study were kept on pasture. Horse # IV presented at Week 0 with 3.82 cm³of hoof lesion volume and an improvement at Week 12 of 66.68 total % reduction in lesion volume. Horse # VI presented at Week 0 with 6.73 cubic centimeters of hoof lesion volume and an improvement at Week 12 of 61.43% reduction in lesion volume. It is notable that the right hind foot experienced only a negligible amount of hoof lesion volume during the entire study. Horse # VII presented initially with 4.1 cm³of hoof lesion volume and at Week 12 with 75.51% reduction. The data for the pastured horses is also presented in a graph entitled Hoof Lesion Volume of Pastured Horses.

REFERENCES:

¹ Alliger Patents: # 4,084,747, # 4,330,531
² Kenyon, A.J.; Hamilton, S.G., Wound Healing Studied with Alcide: a Topical Sterilant, Amer. Society of Biol. Chemists 74th Annual Meeting, San Francisco, CA June 5-9, 1983.
³ Kenyo, A.J.; Hamilton, S.G.; Douglas, D.M., Controlled Wound Repair By Antimicrobials That Alter Fibroplasia, Amer. Assn. For Laboratory Animal Science, 34th Annual Session Nov. 6-11, 1983.
4 Wildenstein, Michael, American Farriers Journal, December 2003, Volume 29, Number 8.