Chronic Foot Abscess in a Horse

A fifteen year old gelding presented to PHD veterinary services for the complaint of recurrent foot abscesses. Over the past 2 months, the gelding has suffered from 2 abscesses in the same foot. Physical exam revealed a draining abscess from the outside (lateral) margin of the sole and the horse was lame at the walk. A radiographic study of the foot was performed. In Figure 1, the lateral view of the foot is represented. There is no evidence of laminitis and there appears to be adequate sole depth (>1cm). However, careful examination of the palmar (bottom) portion of the coffin bone revealed an area of radiolucency in the bone (yellow circle and yellow arrows).

Figure 1

In Figure 2, the same radiolucency can be seen in the outside (lateral) portion of the coffin bone (yellow arrows and circle) AND is associated with the radiolucency (blue arrows)  immediately below it which is the current abscess that is draining from the bottom of the foot.

Figure 2

In Figure 3, the downwardly projected radiograph clearly identifies the defect within the coffin bone (yellow arrow and yellow circle).  In addition, the full extent of the abscess is noted by the blue arrows which nearly encompass the entire lateral aspect of the sole. The "black hole" noted inside the yellow circle corresponds to a region of the coffin bone which as been invaded by infection or possibly a tumor. The most likely scenario is a chronic abscess which has resulted in osteomyelitis (bone infection) of the coffin bone. Further diagnosis and treatment will involve a veterinary surgeon and exploration of the coffin bone defect. 

Figure 3

 Typically, foot abscesses do NOT result in a bone infection. However, if the initial abscess is not treated aggressively with disinfecting foot soaking and proper bandaging, it is possible to have such a complication. I typically recommend 7 days of epsom salt solution soaking along with bandaging the foot with a variety of "packing" material. In the case of large sub-solar abscesses, I strongly recommend the use of a hospital plate or specialized boot.

Hock Arthritis in a Horse

A 14 year-old gelding presented to PHD veterinary services for the complaint of left hind limb lameness. The lameness had been noted for 6 months with minimal clinical improvement after several months of pasture rest. On presentation the gelding was a grade 3/5 lame in the left hind limb when trotted in a straight line. Flexion of the lower limb and upper limb did NOT worsen the lameness. In addition, the lameness did NOT worsen when lunged in either direction. Physical exam of the left hind limb did not identify any swelling or joint effusion however the gelding's range of motion of the hock joint was reduced. Radiographic evaluation of the limb was elected as the best option for identifying the source of lameness in this horse.  In Figure 1 and 2, the lower hock joints are identified as the following: PIT= proximal intertarsal joint, DIT= distal intertarsal joint, and TMT= tarsal metatarsal joint. 

Figure 1

Figure 2

In Figure 3, the lower hock joints are circled in blue and the yellow arrows are highlighting areas of significant arthritis across the front of the lower hock joints. For comparison, in Figure 4, the right hock is imaged in a radiograph and there is no evidence of arthritis in any of the hock joints.

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Figure 4

In Figure 4, the front of the lower hock joints appear disfigured (yellow arrows) by the advanced arthritis present. In addition, there is evidence of arthritis in the most proximal hock joint (tibio-tarsal joint) which significantly worsens the prognosis for this horse (Figure 4, red arrow).

Figure 4

The cause of such advanced arthritis in only one hock suggests trauma or a previous infection. Unfortunately, the full history of this horse was not available. Recommendations included a daily anti-inflammatory medication and intra-articular therapy with corticosteroids. Prognosis is guarded for soundness due to the involvement of the tibio-tarsal joint and the degree of arthritis noted in the lower hock joints.

Fractured Tail Bone in a Horse

A seven year-old gelding presented for a history of recent trauma via a pasture mate over the region of the tail head. The gelding was able to move his tail however there was firm swelling around the region and he was tender to palpation (Figure 1 and 2). Physical exam performed 2 weeks after the injury was first noted revealed moderate swelling yet no pain on palpation. In addition, the tail had a normal range of motion and there was normal tail anal tone.
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Figure 1

Figure 2

A radiographic exam was performed and a mildly displaced fracture of the first coccygeal bone was identified. In Figure 3, the vertebrae in the center of the image has what appears to be a cap on the spinous process which represents the mildly displaced fracture. In Figure 4, the coccygeal vertebrae in question is magnified and the fractured bone is highlighted with the red arrows. The yellow arrow in Figure 4 identifies the fracture line through the spinous process of the first coccygeal vertebrae.

Figure 3

Figure 4

The fracture will heal with time and there should not be any negative, long term effects from this injury. However, there remains a concern of the development of a sequestrum (de-vitalized bone) at the fracture site. A sequestrum would develop if the fracture resulted in loss of blood supply to the fractured fragment. This would result in the likely development of a draining fistula as the body attempts to reject the sequestrum. The gelding will be given several weeks of rest and relaxation before returning to light riding. A follow-up radiographic exam will be performed in 2-4 months.

Fungal Plaque in a Horse

A 7 year-old gelding presented to PHD veterinary services for the complaint of mild epistaxis (bloody nasal discharge). Endoscopic exam of the nasal passages identified a golden colored mass (Figure 1) that was covered in blood and was located within the opening to the ethmoid turbinates. The mass was diagnosed as an ethmoid hematoma based on location, appearance, and behavior. The client was given the option of surgical removal or treatment with intra-lesional doses of formalin. Based on the relatively small size of the ethmoid hematoma it was decided to attempt treating 1-2x with formalin and if there was not complete resolution then surgical resection would be pursued.

Figure 1

Four weeks after the first injection of formalin, a follow-up endoscopy noted significant reduction in the size of the ethmoid hematoma (Figure 2) and what appeared to be a second mass deeper within the ethmoid turbinates. The second ethmoid hematoma was not visualized during the initial exam because the first ethmoid hematoma was blocking the view! Based on these findings, the second ethmoid hematoma was injected with formalin in a similar fashion as the original ethmoid hematoma.

Figure 2

Six weeks after the second formalin injection the client reported that there was a slight yet persistent bloody discharge from the affected nares. Endoscopic exam revealed what appears to be a fungal plaque (black/white/yellow) adhered to the site of the ethmoid hematoma (Figure 3 and 4). This is an unusual finding and may prove to be a challenging complication. Fungal plaques have a predilection for vascular tissue and can infect the upper airway of horses. Fungal infection within the guttural pouch of a horse is well documented and can result in a catastrophic hemorrhage if not diagnosed and treated early. Fungal infection within the ethmoid turbinates is not common in my experience. Often these fungal plaques do NOT respond to systemic anti-fungal medication and must be either removed or treated aggressively with topical medication.
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Figure 3

Figure 4

The current clinical plan for this horse is medication with oral anti-fungal medication for several weeks. If there is no change, the fungal plaques will be treated with topical anti-fungal medication. Stay tuned....

Finally after 4 weeks of anti-fungal medication, there is no evidence of a fungal plaque and there is NO evidence of an ethmoid hematoma (Figure 5). The ethmoid turbinates are visible for the first time in this horse since the initial exam. Although there is no evidence of an existing ethmoid hematoma, these tumors commonly reoccur hence the gelding will be monitored closely for the next 12 months. 

Figure 5

Coffin bone rotation and Sinking in a donkey.

Sadly, I share the story of my very own donkey named "Lollipop". She is approximately 12 years old and every summer gets a bit foot sore when the green grass is lush. Through benign neglect and some luck, she has recovered every year with just a few days of phenylbutazone treatment! This year has been different. She has been lame in left front foot for over 2 months. Initially, she was lame in both front feet and I kept her feet supported with impression material and bandages. After 30 days of foot bandages, I switched to Soft Ride boots with removable orthotics designed for acutely foundered horses. The donkey remained lame in the left front foot hence I broke down and radiographed both front feet. On the day that the radiographs were taken, I noted that the entire coronary band was soft and painful in the left front foot!!
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Figure 1

Figure 2

.Figure 1 is a radiographs of the left front foot and Figure 2 is of the right front foot. There is evidence of chronic laminitis in both front feet with coffin bone rotation and pedal bone lysis. However, the most concerning observation was the radiographic evidence of coffin bone "sinking", predominantly in the left front foot. This occurs when the lamina becomes detached all the way around the foot and can result in the entire hoof sloughing off the foot!! In Figure 3 and 4, the red line corresponds to the coronary band and the blue arrow is the distance from the coronary band to the coffin joint. In Figure 3 (left front foot), the blue arrow is longer than the blue arrow in Figure 4. This would suggest that the entire bony column has "sunk" into the hoof capsule. This would also explain why the coronary band was soft and painful. In essence, Lollipop is trying to lose her hoof!  If this was to happen she would likely require humane euthanasia!!

Figure 3

 

Figure 4

Due to the severity of her condition, she is now locked up in a stall and I have placed her left front foot in a cast. The cast will hopefully stabilize the foot/hoof and allow time for healing of the lamina. She is comfortable on 1/2 gram of phenylbutazone 2x per day and other than being annoyed about the stall confinement, she appears stable. Stay tuned and keep her in your thoughts and prayers!!

Fractured Scapula in a Horse

A 5 year-old miniature horse presented to PHD Veterinary services for the complaint of forelimb lameness. The mini had been charged and mounted by a full grown horse 4 weeks prior and subsequently the mini was a grade 4 out 5 lame in the right forelimb at the walk. The referring veterinarian examined the mini on the day of the injury and radiographed the shoulder joint. There were no radiographic abnormalities noted. Although the lameness was slowly resolving, the owner and referring veterinarian elected for an ultrasound of the shoulder region. On presentation, the mini was a grade 3/5 lame in the right forelimb at the walk. There was a firm swelling over the center of the right scapula and the mini was painful to direct pressure. There was no muscle atrophy noted and the ambulation of the limb was normal.
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Figure 1

In Figure 1, the spine of the scapula is imaged. The white structures correspond to bone. The yellow arrows point to multiple bone fragments. These ultrasound findings suggest that the spine of the scapula was crushed when the full grown horse mounted the mini. The image in Figure 2 corresponds to an equine scapula and the yellow arrows highlight the spine of the scapula as it extends nearly the length of the scapula.  In addition to the bone fragments of the spine of the scapula, the longitudinal scan of the scapula in Figure 3 suggests a fracture of the body of the scapula. There is a "step" or interruption of the bony margin which is indicated by the red arrow in Figure 3. 

Figure 2

Figure 3

 In Figure 4, the abnormal scapula (left image) is compared to the normal scapula (right image). Clearly, there are multiple bone fragments present at the site of the fractured scapula. The prognosis for this mini is good given time to heal. The mini is developing a firm, bony callous over the fracture site to stabilize the scapula and it's soundness has improved since the injury. It remains possible that the mini may develop a sequestrum (dead bone) due to the multiple bone fragments which would result in a draining wound. In addition, the fracture of the body of the scapula will need significant time to stabilize before the mini can return to full soundness. This type of injury would likely be more serious in a full size horse due to the weight of the horse. In addition, the radial and suprascapular nerves are often involved in these types of injuries resulting in muscle atrophy and difficulty in proper ambulation of the limb.

Figure 4

Drug Testing and Prepurchase Exams for Horses

A 10 year old, warm-blood mare presented to PHD veterinary services for a prepurchase exam. The standard exam, complete with limb flexion was performed and the mare was found to be completely sound and negative to limb flexion. The buyer requested baseline radiographs of both hocks and both front feet. In addition, it was strongly recommended that a drug screen of the mare's blood be performed for the detection of sedatives, anti-inflammatory medications and corticosteroids.
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Figure 1

Although the mare was sound and did not resent limb flexion, there was radiographic evidence of advanced osteoarthritis of the lower hock joints.  In Figures 1,2, and 4, the yellow arrows are pointing to radiographic changes consistent with arthritis along the front or dorsal aspect of the lower hock joints. There is new bone growth (osteophytes) and joint space narrowing. In addition, in Figure 3, the blue arrows are pointing to the area of sclerosis surrounding the lower hock joints which suggests chronicity of the arthritis and the apparent "fusion" of the distal hock joints. These radiographic changes are advanced and are surprising considering that the mare was sound for the prepurchase exam.

Figure 2

Figure 3

Even though the mare was sound, I did NOT pass this horse for sale and intended use based on radiographic findings and advised the buyer to at least wait for the drug screen results prior to making their decision!   The standard drug screen takes approximately 5-7 days for results to be reported. Interestingly, the mare's blood tested positive for high doses of an anti-inflammatory medication which likely explains why this horse was sound and negative to limb flexion even though she has advanced arthritis in the lower hock joints. This case represents yet another example of the importance of drug testing and base line radiographs for prepurchase exams!! Admittedly, it is a financial slippery slope once you begin the radiographic exam regarding how many areas to evaluate, however; areas of high probablity such as the hocks and front feet should always be considered!

Figure 4

Allergic Airway Disease in horses.

In the past 30 days (July 8 - August 8) I have examined 10 horses for the complaint of coughing and poor performance. The horses have ranged in age from 8 to 19 years of age. There has been no commonality with regards to sex or breed. However, they all live in Florida and it is the hottest month of the year!  Through a series of diagnostics which include a re-breathing exam, upper airway endoscopy, and trans-tracheal wash, all 10 horses have been diagnosed with allergic airway disease (AKA: heaves or COPD). None of these horses had previously been diagnosed with this condition. 
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Upper trachea with large amounts of sputum present.

Lower trachea with thickened mucosa due to chronic inflammation

Allergic airway disease in horses typically results in coughing, increased respiratory effort, increased "abdominal" breathing, exercise intolerance and weight loss. If not managed properly, the condition worsens from year to year and can result in the death of the horse!! I have posted a blog previously discussing this disease and how it should be diagnosed and treated. Please click on the link below to read my blog from last year regarding this condition.

Allergic Airway Disease in a Horse

Collapsing Trachea in a Miniature Horse

A three year-old miniature stallion presented to PHD Veterinary Services for the complaint of open mouth breathing and a "honking" sound during respiration. At presentation, the stallion was agitated and was continuously pawing at his muzzle with his mouth open. The stallion was mildly sedated for the endoscopic exam and interestingly, his breathing became more normal. The most proximal trachea (Figure 1) appeared normal in diameter however the lumen quickly became narrowed (Figure 2). The trachea was nearly completely collapsed for approximately 6 cm at the level of the thoracic inlet. Distal to this area, the trachea appeared normal (Figure 3).

Figure 1

Figure 2

Figure 3

Normally, the lumen of the trachea is continuous, extending from the larynx to the primary bifurcation of the trachea (Figure 4). Unfortunately, the miniature horse breed is predisposed to the condition known as collapsing trachea. The condition is often diagnosed shortly after birth or can develop later in life if the horse is allowed to gain excessive weight. A common clinical complaint is that of a "honking" sound during heavy respiration. The severity of the collapsing trachea depends on the location and the extent of the narrowed lumen. The closer the area of collapse is to the chest cavity, the worse the prognosis. There are reported cases of collapsing tracheas in miniature horses that were repaired via intra- and extra-luminal stents. Unfortunately, they are short term fixes and often do not provide a long term solution.

Figure 4

Keratoma in a horse!!

A 10 year-old gelding presented to PHD veterinary services for a history of recurrent abscesses in the left front foot. Over a period of 6 months, the gelding developed 3 distinct abscesses which ruptured at the coronary band. At presentation the gelding was mildly lame and there was no active drainage from the most recent abscess rupture. A radiographic exam was performed to determine if there was a radiographic explanation for the development of multiple foot abscesses in the same foot.

Figure 1

The most notable finding in the radiographic exam was evidence of coffin bone rotation (Figure 1 and 2). In Figure 2, the red dotted lines should be parallel. The red line on the left corresponds to the dorsal hoof wall and the red line on the right corresponds to the dorsal aspect of the coffin bone. The reason they are not parallel is because the red line on the right has rotated in a down ward direction approximately 10-12 degrees. Evidence of coffin bone rotation suggests a history of laminitis or founder and this might explain the recurring foot abscesses. In addition, the yellow lines in Figure 1 highlight the hoof wall defect which developed secondary to the recurrent foot abscesses. There are thin areas that appear radiolucent (black lines) which extend from the dorsal hoof wall defect (yellow lines) down towards the bottom of the foot. These radiolucent lines may correspond to remnants of draining tracts from the recent abscesses.

Figure 2

Figure 3

In Figure 3, the radiographic beam is aimed downward through the hoof and coffin bone. The image on the left is the left foot and the image on the right is the right foot. The yellow dotted circles correspond to the tip of the coffin bone that appears to be more radiolucent (less bone) in the left foot compared to the right foot. This would suggest some sort of pathological process affecting the tip of the coffin bone in the left foot. The possibilities for these radiographic changes include laminitis, chronic abscess with bone infection (osteomyelitis), and keratoma. An MRI study of the foot was strongly recommended to determine the cause and provide key information for likely surgical exploration.

Figure 4

The gelding was referred to the University of Florida for MRI of the front feet. A large area of concern was highlighted in the MRI that was either a chronic abscess or a keratoma. Subsequently, a partial hoof wall resection was performed by Dr. Andrew Smith and his surgical team at University of Florida's college of veterinary medicine (Figure 4). Once the hoof wall was removed, a large keratoma (yellow dotted lines) was identified and removed. A keratoma consists of  a benign tumor of keratin or horn-producing cells. The keratoma will grow between the coffin bone and the hoof wall causing distortion of the hoof wall, recurrent foot abscesses, and laminitis. Surgical resection is the only option but should be preceded by an MRI to identify the keratoma and its dimensions. Prognosis is good for a full recovery assuming the entire keratoma is removed at the time of surgery.

Special thanks to the Dr. Andrew Smith and the University of Florida's radiology department!

Summer Sore Time is here!!

Although I have already written a blog concerning summer sores in horses (go to: http://michaelporterdvm.blogspot.com/2013/06/habronemiasis-summer-sore-in-horse.html) , the condition is a recurring one and it deserves another visit!! Below are several images from different horses that suffer from recurring habronemiasis or equine summer sores. The horse in Figure 1 suffers from recurring habronemiasis in all 4 limbs, whereas the horse in Figure 2 recently developed summer sores along his sheath!! These summers sores are medium in size and treatable with topical and systemic medication. However the horse in Figure 3 is suffering from a horrible summer sore of his lower limb that has not been treated but allowed to grow unabated and permanently disfigure the limb. It is frustrating to the horse owner that these lesions tend to return every year with the return of flies however if treated early and aggressively, management of this condition is quite do-able!!

Figure 1

Figure 2

For horses with recurring or first time habronemiasis, I recommend the following:

1: Systemic treatment with a dewormer containing Ivermectin. Treat twice, approximately 3-4 weeks appart.
2: Topical treatment with Dr. Porter's summer sore cream!!
3: If the summer sore is excessively large or in a location that is difficult to treat with topical medication, I recommend systemic therapy with corticosteroids. I prefer to medicate with a tapering dose of oral prednisolone over 30 days.

It is critical that the barn management incorporate a fly control program of their choosing. In addition, horses which suffer from recurring summer sores need to be treated the moment there is any redness or mild irritation present in the old summer sore sites!! If treated early, the lesion will typically respond favorably to topical medication without the need for systemic corticosteroids! 

Figure 3

Fractured Spinous Processes in a Horse

A 10 year-old gelding arrived to a horse show and was seriously injured during the unloading from the trailer. The rear gate was lowered and the horse remained standing in the trailer with the "butt bar" in place (Figure 1). For some unknown reason, the horse panicked and attempted to unload with the butt bar in place. The horse became trapped below the butt bar and struggled for several minutes before the owner was able to release the bar. Within moments of the event, the horse's withers became swollen and very sensitive to the touch. The gelding was treated with systemic anti-inflammatory agents and returned home in the trailer WITHOUT the  butt bar!

Figure 1

Two weeks after the injury, the gelding presented to PHD veterinary services for a radiographic evaluation of the withers. In Figure 2, the green line outlines the withers of the horse. The bone-like fingers projecting upward below the green line are the spinous processes which make up the withers. On physical exam there was minimal swelling over the withers however the horse was very sensitive to any pressure and there appeared to be a "dip" in the very bottom of the withers (yellow arrows).

Figure 2

Radiographic evaluation of the "dip" in the withers confirmed multiple fractures of 3 spinous processes (yellow arrows in Figure 3). The first spinous process that is fractured appears to be in several fragments and displaced from its normal position. The second spinous process appears fractured but not displaced and the third process appears to have an avulsion of the most proximal aspect of the spinous process. Although it is likely that these fractures will heal in time and be some what stable, the current concern is the development of a frustrating condition known as fistulated withers. This  occurs when a piece of fractured bone becomes devitalized of blood supply and subsequently "dies" becoming a sequestrum. The body's natural response is to rid itself of the sequestrum and will develop a draining wound that originates from the sequestrum. These wounds do NOT resolve until the sequestrum has been removed and this can be extremely challenging from a surgical stand point. Currently there is not evidence of a sequestrum however it will take several weeks/months to determine if one will develop. Prognosis for return to riding will depend the development of fistulated withers and how comfortable the horse is once the fractures have stabilized.

Figure 3

Rehabilitation of horses through controlled swimming!!

The images below were taken at The Sanctuary Sports Therapy and Rehabilitation Center in Ocala Florida. The horse that is entering the water and swimming across the equine swimming pool is in the process of being rehabilitated for a ligament injury. This horse has already under gone 8 weeks of strict stall confinement and several doses of extra-corporeal shockwave treatment for his injury. Horses that have spent extensive time in stall confinement are at risk of re-injury or a new injury once they are returned to work. This is because the are out of condition yet willing to run, buck, jump, and generally misbehave!! Unfortunately, most horses lack a good sense of self preservation!! 

 Depending on the type of injury, low-impact exercise is advantageous for rehabilitating horses after a lengthy confinement. Unfortunately, due to their significant weight and relatively small cross-sectional area of their hooves, horses tend to stress their musculoskeletal structure even at the walk. In addition, many can be fractious and unsafe to handle and/or ride after an extensive period of confinement. As such, swimming provides an excellent form of exercise that is very low-impact and safe. Fortunately, most horses enjoy swimming and are quick learners!!

My recommendation for horses returning from a lengthy period of stall confinement includes 30 days of swimming for 20 minutes, 4-6 days per week. In addition, the horse will be hand-walked for 10-20 minutes per day. The remainder of time the horse remains in stall confinement. In my opinion, this is far superior to simply turning the horse out in a small paddock for 30 days.

http://www.sanctuaryequinerehab.com/