EQUINE CANKER

1. All breeds are effected by canker, but draft/draft crosses seem to have a higher rate
2. All ages and sexes can get it
3. Can be in one, two, three, or all four feet:
   • In drafts, it is usually more in the hind feet
4. Your farrier says the horse has canker
5. Early Signs:

• Very bad odor
• Exudate that is white/yellow like melting cheese
• Tentacles of abnormal tissue like an octopus (in advanced cases)
• “Blooms” of proud flesh and abnormal tissue that looks like cauliflower
• Tissue bleeds very easily when trying to clean out the feet
  • Cleaning out feet does not cure the problem
• Mild advancing to profound lameness where they begin to lean against posts,straw bales, keep feet up, hop, toe walk
• Blood on concrete floor seen due to canker dripping blood

1. MSM
2. Magnesia
3. Zinc
4. Bismuth
5. Metronidazole
6. Ketoconazole
7. SMZ/TP
8. Salicylate

@jadenemaloy What a long difficult 4 weeks it has been, chance has been on box rest for 4 weeks which means going up to the yard before and after work and treating his foot daily. Theres just not enough hours in the day. Fingers crossed we will have beaten this in a few weeks🤞#canker #treatment #drreillyprotocol #cankerpowder #horses #horse #equine #equestrian #petcare #boxrest ♬ When I’m Gone - sriwati

Warning: Graphic photos

• Both have a bad odor
• Both improve with dry bedding/dry turnout areas
• Both improve with picking out feet regularly

• Anaerobic bacteria
• Aerobic bacteria
• Papilloma Virus
• Fungus
• Proud flesh (exuberant granulation tissues)
• Damaged frog/sole tissue
• Spirochetes
  Why canker powder’s “soup” of multiple ingredients is needed.
  Only metronidazole will fail.
  Only antifungals will fail.
  Only cutting out abnormal tissue will fail.

1. Viral – bovine papilloma virus
2. Bacterial – anaerobes, including Treponema Spirochete
3. Bacterial – aerobes
4. Proliferative abnormal tissue – proud flesh/hyperkeratosis, hyperplastic tissue
5. Fungal elements probable
6. Nematode (worms) probable

1. Treponema in soil is worldwide
2. Bovine papilloma virus is widespread
3. Peloda worms in soil is worldwide
4. Bedding in straw increases infection possibility due to organic matter being in direct contact with dirt. Also straw absorbs urine less, so more moisture allows for increased bacterial counts.
5. Genetic component – horse may be more prone
6. Drafts more prone – perhaps weight pushes dirt into crevices in foot in larger amounts. Perhaps larger foot means more prone to frog/sole wounds which allow dirt in more often.
7. The top reason I have seen as a veterinarian is due to inadequate hoof trimming schedules - instead of on a 4-6 week cycle, it is seen in horses on 8, 12, 16 week cycles. The hoof walls are overly long creating a large space for dirt/manure/urine to pack into it. This is especially seen in draft horses - owners mistakenly think they need to be trimmed less.

1. Tennessee walking horse with Horse papillomatous dermatitis had spirochetes and the worm pelodara strongyloides within the abnormal tissue
2. This worm is a saprophyte – it lives in dead or decomposing organic material
3. The area had classic epidermal hyperplasia and keratotic hyperkeratosis
4. Antibiotics were used to treat the spirochetes – tetracycline class
5. Pelodera strongyloids diagnosed also in humans, dogs, cattle, and horses

1. In humans, pelodara strongyloids creates an itchy, red, rash
2. First line of therapy is Ivermectin given to people

1. Ivermectin in people helped strongyloidiasis
2. 88% cure rate with Ivermectin
3. Well tolerated

1. Ivermectin used to treat equine strongyloides – strongyloids westeri in foals with “high efficacy and no side effects”

1. Pelodera strongyloides seen in dogs on damp ground or damp bedded straw. This is a good reason to avoid straw as bedding in horses – use shavings
2. Creates inflammatory skin reaction as larvae burrow into skin

1. High rate (25%) of a cattle herd infected with pelodara strongylades
2. Created marked thickening of skin, scurfy, and hair loss
3. A moist/filthy environment was suggested as a mechanism for infection

1. Pelodera strongyloides in an 18 year old man – itchy, follicular papulopustules on skin

1. 6-month old baby with pelodera strongyloides

• #1 Regular scheduled hoof trims every 4-6 weeks throughout the year.
• Bedding
  • Use shavings to dry out feet better than straw. Straw has organic dust which includes bacteria/mold and absorbs urine less, so the feet are exposed to water more. Pelodara larvae live in rotting organic debris like wet straw.

• Pick feet out daily/inspect feet daily

• Antiseptic
  • Apply Venice of Turpentine to soles of all four feet 2 times a week for life – antiseptic

• Help the Barrier
  • Understand that the hooves/soles are extensions of the skin, so help that barrier be its best:

1. Health-E Vitamin E: 1 scoop a day = 5,800 IU of Vitamin E. This is the strongest Vitamin E in the USA, has all eight forms of alpha tocopherol, and is ester stable so it is good for 2 years in heat/light/air. Vitamine E is the #1 antioxidant of the epidermal tissue making up frog/sole.Why Vitamin E? Keeps immune system in peak shape in studies.
   Click here for information on Vitamin E
2. Omega 3 helps skin – add flax or chia seed to their diet – easy, simple, and cheap
3. Pasture

   -Management of pasture to decrease area of standing water
4. Genetic Component

   -Family lines of an individual horse with canker need to be inspected daily even more. If a canker horse has a brother on the program, a keep a sharp eye on them.
5. Deworming

   -Regular deworming program reduce the nematode aspect of canker – do Ivermectin 3x per year
6. Avoid Long Term Corticosteroid Use

   -Lowers immune system to allow bacteria in
7. Stress Reduction

   At the 2020 Hoof Summit Canker Presentation with Dave Giza, Dr. Mathias and Dr. Reilly, several farriers commented on early canker stages seen in debilitated/stressed horses. Could this be a factor in allowing opportunistic organisms to flourish? Probable.

   a. Vitamin E is an immune stimulant - several studies - start adding to diet. Also helps in reducing stomach ulcers.

   b. Test T4 thyroid - many horses are low end of normal and may need to be in high end of normal with Thyro-L, an immune stimulant, supplementation.

   c. Future?

   -Test Vitamin E levels - if low, supplement

   -Test CBC to see if immunity low, low WBC

   -Titers for BPV? High or Low

   -Immunostimulatory Herbs

• These can destroy normal tissue and create crevices that canker flourish in. They can also spill over hoof tissue onto skin of the heels/pastern and create damage.

• These require general anesthesia, so added risk and costs, and the canker will return. Often normal tissue and structures are removed unnecessarily.

• This treatment cannot reduce proud flesh aspect of canker or kill harmful bacteria of the disease. This therapy usually also requires surgical removal of some abnormal tissue prior to maggot placement. A better option is the surgical removal of abnormal tissue and placement of horse canker powder.

• Often requires multiple separate treatments due to canker reoccurs. This therapy also requires surgical removal of canker tissue prior to the procedure and often, topicals are required after freeze firing. A quicker, easier way is surgical removal and placement of horse canker powder.

• One study suggested this to help in reducing proud flesh aspect of canker but it’s a therapy with problems:
  • Immune Suppression Caused by Steroids: This can increase bacterial infections. Also Cushings horses should avoid this due to raising of glucose levels and their cortisol levels are already high. In addition, corticosteroid reduces muscle mass by breaking it down to create glucose, so it is not helpful in older horses with muscle problems.
  • Laminitis: Increases insulin, so it is not good for insulin resistant horses and can increase laminitis episodes in IR horses.
  • Proven to create IR in normal horses with extended use.
  • Topical option: In horses with advanced proud flesh, I will add prednisolone to the canker powder - so corticosteroid benefits without side effects.

• Human Health Hazard. Other antibiotics like SMZ-TP, tetracyclines, metronidazole, and ketoconazole are much safer.
• Expensive

• Click Here to read: Dr. Apprich, “Equine Hoof Canker: A Clinical Trial of Topical Cisplatin Chemotherapy”
  • In the study, a major problem was that included in with cisplatin was metronidazole – so it’s very difficult to see which medicine was having effect.
  • Of 10 horses treated, 6 out of 10 had less than 2 months of follow-up to see if it reoccurred. So, no idea what happened after that.
  • In 1 out of 10, canker did reoccur when tracked for 14 months post-treatment.
  • Due to health and safety concerns, “made this therapy viable only in a hospital setting.”
• Click Here to read: Dr. Florea, Cancer 2011, Cisplatin Activity/Side Effects
  • “Cisplatin may lead to diverse side effects such as neuro and/or renal toxicity or bone marrow-suppression”
  • “Despite the positive effects of platinum compounds, they are poisons”
  • “Cisplatin creates DNA damage to tissue – considered a DNA-damaging anticancer drug”
  • Due to the potential to damage normal tissue on the hoof or horse skin if split or runs accidentally onto it; and the multiple (at least 14) times you need to handle it as a veterinarian, along with the dangers to human skin and bone marrow problems, it’s wise to look for other safer treatments for horse canker. Also, this treatment cannot be done at a barn or stable – it would only be at a hospital, so costs would be much greater.

• 1962 – Lameness in Horses (Dr. Adams)
  • “Guarded to unfavorable prognosis”
• 1998 – The Lame Horse (Dr. Rooney)
  • “Less than hopeful prognosis”

• Cattle that had PCR biopsy of skin near the hoof that were negative for treponema, still had positive PCR for for treponema on healthy hoof tissues. These cattle were brought to a farm with cattle with present cattle digital papillomatous dermatitis levels.
• This means a simple culture of treponema of a horses foot will NOT mean it’s canker positive.
• This also means that treponema are present in the dirt at a farm with a horse with canker most likely. Whether treponema is ubiquitous (all over) to all horse farms is unknown. Whether the load/amount of treponema at a farm contributes to more canker is unknown.

• Cattle digital papillomatous dermatitis is worldwide – so is horse canker.Cattle digital dermatitis has the same treponema found in horses. Treponema denticola-like spirochetes found in diseased cattle digital dermatitis (76.5% of cases).79% of human endodontic (gum line) abscess showed PCR genetic testing also for treponema denticola.
• This treponema spirochete effects many animals – humans, horses, dogs
• In cattle, they isolated several species of treponema in diseased tissue – not just treponema denticola. It’s very possible more treponema species than just treponema denticola-like will be found in horse canker

• In cattle papillomatous Digital Dermatitis in a Japan study, 40 different spirochete strains were found
• Cattle papillomatous digital dermatitis creates hyperkeratotic papillomatous lessons with long hair like projections – this is the same thing found in horse canker
  • Many different types of bacteria cultured in BPDD – unclear whether some or all involved, but a large number of spirochetes found.
• Culturing out treponema in diseased tissue is a difficult process due to growth rate of treponema being poor.
• Also, presence if other fast growing bacteria in lesions prevents treponema isolation. No selective growth media for these treponema has been developed
  • So if culturing and have a treponema negative result, that does not mean they were NOT present.
• Did find systemic antibodies against certain spirochetes in diseased tissue, so an immune response is being made, but it may not be protective or due to so many species of spirochetes, the genetic diversity is so great that it evades immunological responses to clear infection.

• Treponema denticola is a key pathogen in human periodontitis (gum) disease.
• This spirochete creates a large inflammatory reaction to tissues around it – TNF, IL-1, IL-6, IL-8, MMP, prostaglandins are pro-inflammatory cytokines that all increased.
• So in horses, it’s setting off inflammation in hoof canker tissue.

• Metronidazole antibiotic indicated against certain anaerobic infection, safe in humans, widely used.
• When studied between just cleaning, just metronidazole, or cleaning and metronidazole, the cleaning and metronidazole dropped infections the most – by 79% – they did not eliminate it, but there was a huge reduction.
• Metronidazole treated people also had less bleeding of gums post treatment.This is why metronidazole is important in canker therapy of horses.

• Treponema denticola actively detaches fibroblasts from gum tissue, leading to tissue detachment. It is actively destroying tissue – this allows other bacteria to move in.
• Metronidazole helped to “markedly reduce the detachment response”.
• Metronidazole helps in protecting tissues infected with spirochetes.

• Using metronidazole topically is effective and safe, even on human faces to treat acne. Had a 88% patient satisfaction and redness on face decreased by 85%.
• “Found effective and safe”

• A study mixing metronidazole with benzoyl peroxide for acne showed good effects over an 8-week period. Again on human faces, this combination was safe.
• Benzoyl peroxide is an active ingredient in Clearasil used in teen acne

• Doxycycline helped – cleaning/debriding area alone did not help – need doxy added
• Found that diabetes that were treated had better glycemic control. This may be of interest in IR or cushing horses – reducing infection, reducing pain of canker may help in these diseases.

• Doxycycline can concentrate in tissues above the levels found in bloodstream.

• The correct dose of Doxycycline is 10 mg/kg body weight every 12 hours. This means in a 1,100 pound horse, the dose is 5 grams AM & 5 grams PM.

• Thanks to Dave Giza, farrier, for this idea. He mentioned that spirochetes in lyme disease and spirochetes in canker disease. So, if Doxy in lymes, why not oral Doxy in canker? This idea cut clearing canker from 60 to 30 days.
• Dose even in 1800+ lb Drafts we still do 5 grams oral 2X/day – been very effective. So in horses 1000+, we do this dose. In horses 500-1000 lbs we do 2.5 grams oral 2X/day.
• We also in 2023 added Doxy to the topical powder
• Not only is Doxy effective against spirochetes, also effective against papilloma virus which also in all cankers.

  Click here to see Dr. Zhao’s article on Doxy in human papilloma

• Click here to see Dr. N Evans study in the Journal of Clinical Microbiology (2009) on the “Association of Unique, Isolated Treponemes with Bovine Digital Dermatitis Lesions”

1. DNA testing of horse canker showed in 24 of 24 cases of Bovine (cow) papillomavirus (BPV)
2. Viral sequencing is 98% BPV in horse canker
3. Testing of horse tissue with no signs of canker showed 13 of 13 times , no BPV
   Conclusion: BPV is an active contributor to horse canker. BPV in cattle produces many of the signs seen in horses such as hyperkeratosis, acanthosis, and moist pododermatitis

1. BPV is common on the skin of normal horses, if they are around horses with sarcoids
2. BPV is common on the skin of horses with sarcoids

• Click here to see Dr. Hessen’s article on oral and topical ketoconazole in the treatment of pityriasis versicolor

• Click here to see Dr. Elewski’s article on “Efficacy and safety of a new once-daily topical ketoconazole 2% gel in the treatment of seborrheic dermatitis: a phase III trial”

• Click here to see Dr. Cauwenbergh’s article on “Topical Ketoconazole in Dermatology: A Pharmacological and Clinical Review”

• Some horses may have infectious osteitis of the coffin bone, if the canker infection undermines the full sole thickness. This requires possible bone surgery, high powered antibiotics. Often in these, Naxcel is very helpful.
• Some horses may have secondary laminitis on top of just the canker
• Some horses may have bits of rock that jam up into/or under the sole and the horse will stay sore until removed.
• Ringbone: especially common in draft horses. Can be painful, so need to treat (equioxx oral helps a lot). Need to put weight on foot and drive powder deep in crevices. Also, can be successful in canker treatment. Owner still sees a lame horse, so thinks horse still has canker but not true! So address this arthritic condition at same time treat canker.

1. Not getting enough pressure to physically press canker powder deep in tissues - so less antibiotic penetration. The plate reduces the horse’s weight pressing powder in.
2. Less frog expansion and contraction - not engaging frog to recover function, especially if had to resect part of it.
3. Less pressure of powder means not suppressing proud flesh - need pressure on it to allow epidermal cells to slide over proud flesh as its receding back.
4. Encasing foot - more moisture.
5. Creating problems for the owner

   -Many horses, especially drafts are unshod - they do not get a shoe.

   -Hind shoe creates kick accident possibly injuring other horses in a paddock.

   -It is another expense not needed.

   -Plate hides status - owners think all ok, so skip daily powder changes. With bandages, they see they are getting worn, so change.
6. Dirt/water can slip in at heel - adding composite material creates even more moisture issues trapping bacteria in addition.
   

1. Antibiotics help in killing/inhibiting growth of organisms, but also have anti-inflammatory, immunomodulatory properties.
2. Seen in Antibiotics from bacteria, fungus.
3. Metronidazole has “many other active other then antibacterial.”
4. Tetracyclines are anti-inflammatory.

1. Proven as a topical therapy.
2. Kills multiple bacterial strains.
3. It’s safe.
4. Helps with fungal infections.
   Click Here to See Bactrim on drugs.com
   Click Here to See Article by Lee, 2001
   Click Here to See Article by Eldesouky, 2018
   Click Here to See Article by Hida, 2005

1. # 1 antioxidant of skin/epidermis.
2. Protects dermal tissue - increases growth factors, improved cell viability.
   Click Here to See Article by Butt, 2017
   Click Here to See Article by Butt, 2019

1. Effective against multiple types of fungus.
2. Proven to work topically and safe. Has been used in human shampoos.
   Click Here to See Article by Kyle,, 2004
   Click Here to See Article by Brooks, 2019

1. Effective Antibacterial.
2. Also helps in dessication, reducing moisture.
   Click Here to See Article by Marzlye, 2019

1. Anti-inflammatory - Reduces cox2, TNF.
2. Anti-oxidant.
3. Increases immune response.
4. Helps permeability - Carrier for drugs (a co-transporter).
   Click Here: Article by Gupta, 2004
   Click Here: Article by Butawan, 2017

1. Lotions are 80% water, and creams are 70% water.
2. In order to reduce bacteria we need to reduce water/moisture.
   Click Here: Ingredient Ratios for Lotion Making

1. Be careful with it! Also heating it can create fire.
2. Have also had 2 cases where it spilled onto pastern skin creating skin irritation and wounds.
   Click Here: More Information on Benzoyl Peroxide
3. Possible source of Benzene Carcinogen.
   Click Here to Read Article

1. In about 5% of canker cases, biofilm is seen. Microorganisms attach to normal tissue on the horse’s foot and these “colonist” bacteria create a gel-like substance (slime) to help bacteria cling to tissue better/longer. This adhesion process allows bacteria to replicate faster but also creates an “armor” around bacteria of a gel that normal antibiotics can’t penetrate. The gel also traps in soil, minerals, blood which helps to increase bacterial count and more biofilm gel.

   The photo above shows blue biofilm protecting the red colored bacteria.

   The photos below are an example of biofilm – canker powder dries the foot out in 3-4 days, but if still “wet” at day 10, need to contact Dr. Reilly to add a biofilm destroying agent – need biofilm removed so antibiotics can access bacteria and kill them.

   

   Wet biofilm examples after 2 weeks of canker powder

1. Oral Tetracyclines covered earlier, but topical use may also be effective. In cattle has been proven to help in reducing pain in pododermatitis.
2. Study using topically in horses (mouth).
3. This has merit and may be added to canker powder.
   Click Here: Article by Zozaya, 2013

1. In Extreme amounts of proud flesh in cases, I will add some prednisolone powder to the canker powder - safe. Never oral or IV/IM steroids.
2. Oral steroids for 3 weeks is a big gamble because so many IR/Cushings horses could push into laminitis - not worth the gamble, especially in 58% fail rate!
3. We have clients that had coronet band disease/dysplasia that when given steroids, horse got massive canker on frogs/soles.

1. Painful burning of canker in an attempt to remove canker.
2. Oral metronidazole tabs taste terrible – will stop eating.
3. Been on long term Bute due to sore, but creates stomach ulcers, so now eat less.