Keratoma, canker, quittor, corn

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Presentation on equine foot conditions: canker, keratoma, quittor, corn

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Keratoma, canker, quittor, corn

  1. 1. UNCOMMON CAUSES OF FOOT LAMENESS: Canker, Keratoma, Quittor, Corn Dane Tatarniuk, DVM
  2. 2. CAUSES OF FOOT LAMENESS:  Navicular Syndrome  Quittor  DDFT  Sole Bruise  Collateral Ligaments  Abscess  Osteoarthritis  Corn  Laminitis  Gravel  P3 Fracture  Keratoma  Navicular Fracture  Penetrating Injuries  Pedal Osteitis  Canker  White Line Disease  Hoof Avulsion  Sheared Heels / Quarters  P3 Subchondral Cysts  Sidebone
  3. 3. 1. CANKER
  4. 4. CANKER Infectious process of the equine foot Chronic hypertrophic, moist pododermatitis of epidermal tissues
  5. 5. CANKER Usually originates in frog, then spreads to sole, bars, hoof wall Any breed; no difference between mares, geldings, studs.  Higher prevalence seen in Draft Horses. Both fore and hind limbs Seen more commonly in the southern states, and more humid regions History of being housed on moist pastures or kept in wet, unhygienic conditions Canker has been seen in horses that receive routine hoof care maintenance.
  6. 6. CANKER VS. THRUSH Canker is often misdiagnosed initially as thrush Sometimes mild lesions are not very distinct, visually If treating thrush and lesion not resolving with routine treatment… = be suspicious of canker
  7. 7. CANKER VS. THRUSH Thrush is limited to lateral and medial sulci, central sulci or base of frog (if fissure present) Canker invades horn of frog anywhere. Biggest difference:  Canker = Proliferation of tissue  Thrush = Loss of tissue
  8. 8. CANKER – CLINICAL SIGNS Often a fetid odor Lesion bleeds easily when abraded Mild lesion - area of focal granulation tissue in frog Severe lesion - frog has ragged, filamentous appearance  Proliferative frog with small finger like papillae of soft, off white material that is “cauliflower” like  Epidermis of frog is friable and is “cottage cheese” like.
  9. 9. CANKER
  10. 10. CANKER – CLINICAL SIGNS Early stages, not associated with lameness, as disease is isolated to superficial epidermis Clinical signs (lameness) increase once lesion becomes diffuse, involves other structures of foot Extremely painful when pressure applied!  Sometimes is best indicator of canker.
  11. 11. CANKER - DIAGNOSIS Culture is unrewarding  Mixed bacterial population isolated from stratum germinativum layer. Biopsy can confirm canker lesion  But not routinely required.  If lesion does not have characteristic appearance, or if in abnormal (non-frog) location = biopsy helpful. Must remove superficial necrotic tissue prior to biopsy Sample taken from margin of lesion 6mm punch biopsy works well
  12. 12. CANKER - HISTOLOGY Histologic Diagnosis:  Proliferative papillary hyperplasia of epidermis Pathogenesis:  infection -> dyskeratosis -> creates filamentous “fronds” of hypertrophic horn
  13. 13. CANKER - ETIOLOGY Etiology unknown. For the longest time, presumed to be anaerobic infection:  Fusobacterium necrophorum  Bacteroides  Other anaerobic organisms Recent paper identifying bovine papillomavirus (2011)
  14. 14. CANKER - TREATMENT O‟Grady‟s Four Principles of Successful Treatment:  1. Early recognition  2. Debridement  3. Routine topical treatment  4. Keep wound clean & dry  promotes cornification
  15. 15. CANKER - DEBRIDEMENT Tourniquet is essential Sedation vs. anesthesia  Extent of lesion, clinician comfort level Trim horse, remove loose exfoliating sole, excess toe or heel. Remove abnormal tissue down to normal cornium  Clear demarcation between abnormal and normal layers Try not to remove excessive amounts of cornium if possible  Will retard cornification after surgery and decrease quality and depth of new sole being produced Balancing act
  16. 16. CANKER - DEBRIDEMENT Instruments for debridement:  Scalpel blade  Electrocautery in cut mode  CO2 Laser Follow with cryotherapy:  Liquid nitrogen most common  Freeze area until it becomes hard – let it thaw – then freeze one more time
  17. 17. CANKER – TOPICAL MEDS Systemic antibiotics not warranted  Lesions resolve with topical only application Topical Options:  Chloramphenicol  Metronidazole powder  2% metronidazole ointment  Ketoconazole/rifampin/DMSO mix  10% benzoyl peroxide in acetone and metronidazole powder
  18. 18. CANKER – TOPICAL MEDS Clean area daily with surgical scrub (betadine) Rinse with saline Apply medication of choice to area Protect with sponge gauze Keep entire foot clean and dry  Foot bandage  Treatment plate  Dry stall & stall rest
  19. 19. CANKER - LITERATURE O’Grady’s Study: 56 cases  21 - single forelimb affected  29 - single hindlimb affected  1 - one forelimb and one hindlimb affected  5 - bilateral forelimb affected All cases treated similar treatment protocol:  „10% benzoyl peroxide in acetone + metronidazole powder‟ 55 cases resolved successfully 1 case reoccurred  Responded the second time to laser photoablation
  20. 20. CANKER - LITERATURE Oosterlinck Study: 30 horses  Only recognized as canker initially in 5 cases  In 10 cases, thrush had been mis-diagnosed and treated for several months  Duration of hospitalization was significantly decreased in horses receiving oral prednisolone for 3 weeks compared to those without this additional systemic treatment  10 horses: No recurrence with treatment  14 horses: Problems reoccurred within the first year  6 horses: Subjected to euthanasia due to diagnosis
  21. 21. CANKER - PROGNOSIS  Prognosis is favorable for complete resolution if treatment instituted early in course of disease  Involvement of sole, bars, hoof wall = prognosis goes down  Multiple limbs affected = prognosis goes down  Duration of aftercare treatment can take several weeks to months  Very important to communicate this to owner
  22. 22. 2. KERATOMA
  23. 23. KERATOMA - OVERVIEW Excessive keratin is produced between the hoof wall and distal phalanx “Oma” implies neoplasia – however this process is not neoplastic Rather, morphological process is hyperplasia
  24. 24. KERATOMA - SIGNALMENT  Initial owner complaints:  Lameness of unknown origin  Abnormal contour to the hoof capsule  Deviation of the coronary band and hoof wall  Most common sites are toe or quarter  Chronic abscessation in foot  Affects any age, any breed  Can be multifocal
  25. 25. KERATOMA - ETIOLOGY Unknown etiology Etiologies proposed include:  Direct trauma to hoof capsule & associated structures  Chronic irritation  Sole abscessation  “Chicken – Egg”  …keratoma causing abscesses or abscesses causing keratoma? Many cases where no history of insult to hoof is present
  26. 26. KERATOMA - DIAGNOSIS Hoof Tester:  Painful response over lesion Diagnostic Analgesia:  Block depends on location of keratoma  PDN, Pastern Semi-Ring, Abaxial Sesamoid Radiographs:  Discrete, semi-circular, radiolucent abnormality with a non-sclerotic (smooth) rim  Irregular, sclerotic margins = think pedal osteitis  Dorsoproximal-65°-palmarodistal view  Only see keratoma itself if mineralized
  27. 27. KERATOMA - RADS
  28. 28. KERATOMA – NOVEL IMAGING Ultrasound:  If near coronary band, can ultrasound lesion  Appears as hypo-echoic, well-delineated soft tissue mass Computed Tomography Magnetic Resonance Imaging
  29. 29. KERATOMA - CT
  30. 30. KERATOMA - MRI
  31. 31. KERATOMA - DIFFERENTIALS DDx for focal, radio-lucent lesion on radiographs:  Fibroma  Mast cell tumor  Squamous Cell Carcinoma  Intra-osseous Epidermoid Cyst  Melanoma  Bone Cyst  Calcified Hematoma  Capsulated Abscess
  32. 32. KERATOMA - PATHOLOGY Histology reveals excessive amounts of keratin and hyperplasia of the squamous epithelial cells. Occasionally see granulation tissue and inflammatory cell influx (variable). Gross appearance is a firm, nodular, yellow-grey mass of varying size.
  33. 33. KERATOMA - GROSS PATHOLOGY
  34. 34. KERATOMA - HISTOLOGY Hematoxylin & Eosin, 2x magnification
  35. 35. KERATOMA - HISTOLOGY Hematoxylin & Eosin, 10x magnification
  36. 36. KERATOMA - TREATMENT Complete surgical removal is required  Incomplete removal = re-growth Surgery performed standing or under general anesthesia Partial or complete hoof wall resection  Create two parallel vertical incisions on either side of keratoma  3rd cut made distally at base of the mass  4th cut made proximal to mass (but under coronary band)  Depth – down to the sensitive laminae Cut using motorized burr (dremel), cast cutters, osteotome
  37. 37. PARTIAL VS. COMPLETE Partial Complete
  38. 38. KERATOMA – POST OP Hoof stabilization  Prevents exuberant granulation tissue  Minimizes pain Methods:  Bar shoe with clips on either side of the defect  Prevents independent movement of two portions of hoof wall  Bridge two sides of hoof wall together  Metal strip spanning defect  Screws & figure-8 wire spanning defect
  39. 39. Metal StripFigure 8 wire
  40. 40. KERATOMA - LITERATURE Boys Smith Study: 26 cases  Complication rate from partial resection = 25%  Complication rate from complete resection = 74%  Complications:  Excess granulation tissue  Hoof crack formation  Keratoma reoccurrence  Time back to work shorter with PR over CR  Median time 8 months (PR) vs. 10 months (CR)
  41. 41. KERATOMA - LITERATURE Cont… Boys Smith study: 26 cases  History of abscessation in 92% of cases  Radiographic signs present in 96% of cases  Reoccurrence of keratoma in 11% of cases  Higher occurrence with PR  Limited surgical exposure…?  Excessive granulation tissue in 32% of cases  Higher occurrence with CR  More hoof wall instability / movement
  42. 42. KERATOMA - LITERATURE Gasiorowski Study: 2 cases  Supracoronary removal of keratomas  Keratomas diagnosed behind or proximal to coronary band (atypical)  Inverted T-incision made 2cm proximal to coronary band  Transect the common digital extensor (V shape)  Body of mass elevated with periosteal elevators  Primary closure
  43. 43. KERATOMA - LITERATURE  Dead space present distally  3mm groove burred out  Creates instability  Countered by placing 1.25mm steel wire sutures  Wire loose enough to allow drainage, but tight enough to prevent shearing forces
  44. 44. KERATOMA - PROGNOSIS Prognosis is good for return to previous function  IF all the abnormal tissue is removed Hoof wall healing will take 10 - 12 months Inform owners that horse will be rested for at least 12 months time
  45. 45. 3. QUITTOR
  46. 46. QUITTOR “Quittor” describes chronic, purulent inflammation of the collateral (ungual) cartilage of distal phalanx.
  47. 47. QUITTOR - SIGNALMENT  Lateral cartilage of forelimb most commonly affected  History of reoccurring drainage from fistulous tracts that overly the affected cartilage
  48. 48. QUITTOR – CLINICAL SIGNS  Abscess formation within collateral cartilage  Break open and drain proximal to coronary band  Owners note drainage from fistulous tracts  Often history of intermittent, severe lameness
  49. 49. QUITTOR – CLINICAL SIGNS  Degree of lameness is variable  Patency of fistulous draining tracts = less severe lameness  Non-patent = no drainage of abscesses = more severe lameness  Pain on hoof tester over affected quarter  Chronic inflammation may lead to permanent foot damage = deformities in hoof wall and soft tissue
  50. 50. QUITTOR - ETIOLOGY Direct trauma to cartilage or soft tissue overlying cartilage  Penetrating wounds and lacerations  Blunt trauma  bruising  damages blood supply  Foot abscesses  Chronic ascending infection of the white line in the quarters  Deep hoof cracks
  51. 51. QUITTOR - DIAGNOSIS  Recurrent swelling of collateral cartilage  1+ fistulous tracts proximal to coronary band  Swelling and pain over collateral cartilage  Hoof tester sensitive over affected quarter
  52. 52. QUITTOR - DIAGNOSIS Need to differentiate between shallow abscesses or ascending infection of the white line (gravel):  Gravel – inflammatory process is often more localized, one fistulous tract  Quittor – inflammatory process is more diffuse, multiple fistulous tracts
  53. 53. QUITTOR - IMAGING Radiographs:  Useful to rule out bone involvement  However lysis of collateral cartilage from infection can‟t be seen on rads  If collateral cartilage has ossified, can see evidence of osteomyelitis  Can determine depth and dimension of draining tract using fistulography (flexible sterile probe)
  54. 54. QUITTOR - TREATMENT  Treatment of choice is surgical excision of necrotic collateral cartilage and fistulous tracts
  55. 55. QUITTOR - TREATMENT Medical management includes systemic and topical antibiotics, foot soaks, and injection of fistulous tracts with anti-septic  Overall, medical management usually fails  May temporarily suppress clinical signs but symptoms reoccur  Regional limb perfusion may be best medical approach  Poor blood supply to collateral cartilage
  56. 56. QUITTOR - SURGERY Hold toe in rigid extension by drilling holes through hoof wall  thread wire through holes  place traction on foot to maintain extension  Tenses joint capsule & retracts it from surgical dissection plane  Decreases chance of entering distal inter-phalangeal joint Curve incision over affected cartilage, reflected proximally Necrotic tissue will be dark blue or red in color Close incision primarily and place foot in foot cast or bandage
  57. 57. QUITTOR - LITERATURE Honas Study: 16 cases  66% of cases became sound after surgical treatment  If drainage less than 1 month, better prognosis for return to soundness versus drainage for more than 1 month  Lateral cartilage was affected in 88% of cases  More trauma sustained laterally?
  58. 58. QUITTOR - PROGNOSIS Prognosis is excellent if complete removal of necrotic tissue is achieved Secondary complications reduce prognosis:  Osteomyelitis of distal phalanx  Septic arthritis of distal inter-phalangeal joint  Infection of digital cushion or other surrounding soft tissue structures
  59. 59. 4. CORN
  60. 60. CORN A corn is a bruise that involves the tissues of the sole  Specifically at the angle formed by the wall and bar Occur more commonly on the medial angle on the forelimbs, however occasionally are seen in the hind If the bruised (corn) site becomes infected -> abscess
  61. 61. CORN - TYPES Corns are divided into 3 categories:  Dry  Red stains, may not have any clinical significance  Moist  Serum accumulates beneath injured epidermis  May cause mild lameness  Suppurative  Infected  Usually more severe lameness
  62. 62. CORN - ETIOLOGY Corns caused by:  Pressure from horse shoe  If shoe left on too long, heel may overgrow the shoe  Creates selective pressure on the sole at the angle of the wall and bar  Application of a shoe that is one half to one full size too small can also increase pressure  Stone wedged between shoe and sole
  63. 63. CORN – CLINICAL SIGNS Variable Varying degrees of lameness  Usually mild to moderate If acute or infected  May get warmth in hoof wall  Increased digital pulse often present
  64. 64. DIAGNOSIS & TREATMENT Often diagnosis can be made by history and visualizing lesion If lesion not apparent….  Shoe should be removed and exfoliating sole removed Hoof testing parallel to sole of the foot will sometimes cause a more significant pain response (vs. perpendicular) Lesions can resolve if source of trauma is removed and horse is rested from heavy work  ie. pull shoe Can also place frog support that will absorb concussion that would normally distribute to the corn site Prognosis: Excellent
  65. 65. REFERENCES: Adams Lameness in Horses, Sixth Ed. Gary Baxter. Wiley-Blackwell Publishing (2011). O‟Grady, S. “How to treat equine canker“ American Association of Equine Practitioner Proceedings. Denver, CO. 1994. Oosterlinck, M. “Retrospective study on 30 horses with chronic proliferative pododermatitis (canker).” EVE 2011. Boys Smith, S. “Complete and partial hoof wall resection for keratoma removal: post-operative complications and final outcome.” EVJ 2006. Gasiorowski, J. “Supracoronary approach for keratoma removal in horses: 2 cases.” EVE 2011 Honnas, C. “Necrosis of the collateral cartilage of the distal phalanx in horses: 16 cases.” JAVMA 1988 Moyer W. “Bruising & Corrective shoeing” Vet Clin North America 1980

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