A Silent Weakness: IOHC/HIF Emerging in Boykin Spaniels
In recent years, Boykin Spaniels have captured the hearts of families and hunters alike with their loyalty, versatility, and eager spirit. Boykin Spaniels are cherished for the joy they bring to our lives. As the breed grows in popularity, however, veterinarians and owners are beginning to notice a health concern quietly emerging: Incomplete Ossification of the Humeral Condyle (IOHC) aka Humeral Intracondylar Fissure (HIF). This genetic condition (Inherited Orthopedic Issue) affects the elbow joint, leaving some dogs vulnerable to painful injuries and lifelong challenges. While not every Boykin will face this diagnosis, awareness is key. In the paragraphs ahead, we share the heartfelt stories of Boykin families whose dogs have experienced IOHC, alongside insight from veterinary professionals who are working to better understand and address this disease—so together, we can protect the breed we love.
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Bulleit's Story
Bulleit, our 5-year-old Boykin Spaniel, was playing fetch—as he loved to do—on a peaceful Sunday afternoon, Mother’s Day, May 12, 2024. We had no idea that day would suddenly and dramatically change our lives. As he was running back with his toy, he suddenly collapsed. We could tell immediately something was very wrong with his front leg and that he needed urgent help. |
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Rougaroux's Story (IOHC)
As the sun set on another training day, our world turned upside down from an injury that will haunt my mind forever. In the almost decade I have been training hunting retrievers, I have never once witnessed an event quite like this. Rougaroux was a fire-breathing dragon, and quite frankly one of the most naturally talented dogs I’ve had the pleasure of hunting over. Having just turned three years old, we were one week shy from what would have been his second Finished test–and this kid was on a roll. Clean marks and tight blinds all evening definitely earned him some “fun-bumpers” at the end of the day! Within a few seconds of me haphazardly tossing him a bumper, my gut wrenched as I heard the sound of screams break out, echoing across the grounds. |
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Happy has always been an aggressive chaser of any kind of prey. So it didn’t surprise us when, in February of 2020, he hurt his right forelimb while pursuing a lure on hard winter ground. He had just taken a very tight turn and dropped his head to grab the lure when he yelped loudly and came up limping. We had never heard him yelp before, but it appeared to be a soft tissue injury so we put him on rest. Happy was a two months shy of three years old at that time. |
More about IOHC/HIF from those who know...
Incomplete ossification of the humeral condyle (IOHC) and humeral intercondylar fissure (HIF) are commonly seen in Spaniel breeds. Historically, it was seen more in Spaniel breeds in Europe but has become an increasing issue in the United States. It was initially thought that there was incomplete fusion of a growth plate in the elbow (IOHC) that led to weakening of the bone and increased the risk factor for elbow fractures with minimal trauma. However, more recently some Spaniel breeds have suffered elbow fractures from minimal trauma that were previously not noted to have IOHC, and as such HIF has been theorized. It is thought that repetitive microtrauma can result in a fissure of the bone and lead to a fracture. It is unknown if this is two different presentations of the same disease condition or two different disease conditions all together.
In any regard, it is vital that any Spaniel breed owner be aware of this condition and the possible genetic component of it. For Spaniels participating in sport or hunting, it is even more important that any minor front limb lameness be taken seriously and worked up appropriately to ensure there is nothing major that could lead to an elbow fracture. A workup would include not only radiographs (X-rays), but also a CT scan. In addition, any elbow fracture in a Spaniel breed should raise concern for IOHC/HIF and as such the contralateral (opposite) elbow should be evaluated.
David Dycus, DVM, MS, CCRP
Diplomate, American College of Veterinary Surgeons – Small Animal
Founder/Orthopedic Surgeon,
Fusion Veterinary Orthopedics
In any regard, it is vital that any Spaniel breed owner be aware of this condition and the possible genetic component of it. For Spaniels participating in sport or hunting, it is even more important that any minor front limb lameness be taken seriously and worked up appropriately to ensure there is nothing major that could lead to an elbow fracture. A workup would include not only radiographs (X-rays), but also a CT scan. In addition, any elbow fracture in a Spaniel breed should raise concern for IOHC/HIF and as such the contralateral (opposite) elbow should be evaluated.
David Dycus, DVM, MS, CCRP
Diplomate, American College of Veterinary Surgeons – Small Animal
Founder/Orthopedic Surgeon,
Fusion Veterinary Orthopedics
“Incomplete Ossification of the Humeral Condyle (IOHC) is a developmental anomaly that predisposes dogs to fractures of the upper arm bone (humerus) and elbow joint. It occurs when the growth plates in the humeral condyle fail to fuse appropriately, leaving an area of fibrous tissue where solid bone should have formed. This weakened region is more prone to fractures. These fractures may occur during normal day-to-day activities, such as during walking, running, or playing. The exact cause of IOHC remains unclear, but it is believed to have a hereditary or genetic basis.”
Cameron B. Seger, DVM
Small Animal Surgery Resident
The Ohio State College of Veterinary Medicine
601 Vernon L. Tharp St.
Columbus, OH 43210
Cameron B. Seger, DVM
Small Animal Surgery Resident
The Ohio State College of Veterinary Medicine
601 Vernon L. Tharp St.
Columbus, OH 43210
Incomplete ossification of the humeral condyle (IOHC) occurs when the two centers of ossification of the humeral condyle (lateral and medial) fail to unite. In effect, the two halves of the humerus bone do not mineralize together as they should. Fusion is expected by 12 weeks of age. Although IOHC can occur in all breeds, spaniel breeds are predisposed to this condition. This would suggest IOHC is a heritable condition.
Applying selection pressure to breeding dogs (e.g. only picking approved dogs) to reduce the probability/chance of propagating/forwarding a disease condition to the offspring is commonly performed in veterinary medicine. Genetic testing, radiographs, ophthalmic exams and hearing testing are all commonly performed to apply selection pressure. However, there is currently no screening test performed to identify dogs with IOHC prior to breeding.
An additional radiograph/x-ray could be taken to help document if a dog has IOHC prior to breeding. A craniocaudal 15˚ oblique radiograph of the elbows can be performed to identify IOHC. In one study (RB Martin, VCOT 3/2010) this radiographic view had a sensitivity of 0.83 and specificity of 1 compared to computed tomography. In effect, when a diagnosis of IOHC was made on a radiograph it consistently agreed with the CT results but an occasional negative diagnosis (“no IOHC”) was incorrect.
If a diagnosis of IOHC is provided from radiographs, breeding should not be recommended.
Mike Conzemius DVM, PhD, DACVS
ACVS Founding Fellow - Joint Replacement Surgery
Gilbert Queen Creek Emergency and Specialty Veterinary Hospital
Queen Creek, AZ 85142
Applying selection pressure to breeding dogs (e.g. only picking approved dogs) to reduce the probability/chance of propagating/forwarding a disease condition to the offspring is commonly performed in veterinary medicine. Genetic testing, radiographs, ophthalmic exams and hearing testing are all commonly performed to apply selection pressure. However, there is currently no screening test performed to identify dogs with IOHC prior to breeding.
An additional radiograph/x-ray could be taken to help document if a dog has IOHC prior to breeding. A craniocaudal 15˚ oblique radiograph of the elbows can be performed to identify IOHC. In one study (RB Martin, VCOT 3/2010) this radiographic view had a sensitivity of 0.83 and specificity of 1 compared to computed tomography. In effect, when a diagnosis of IOHC was made on a radiograph it consistently agreed with the CT results but an occasional negative diagnosis (“no IOHC”) was incorrect.
If a diagnosis of IOHC is provided from radiographs, breeding should not be recommended.
Mike Conzemius DVM, PhD, DACVS
ACVS Founding Fellow - Joint Replacement Surgery
Gilbert Queen Creek Emergency and Specialty Veterinary Hospital
Queen Creek, AZ 85142
| 2010_Prevalence of incomplete ossification of the humeral condyle in the limb opposite humeral condylar fracture: 14 dogs |
From Dr. Denis Marcellin-Little who discovered IOHC
"I am very much looking forward to investigating the genetic roots of incomplete ossification of the humeral condyle (IOHC) in Boykin spaniels. IOHC unfortunately can have a profound negative impact on wellbeing and mobility in dogs. Our team, here at UC Davis, has expertise in genetics, in medical imaging, and in the analysis of bone geometry. We are very well positioned to investigate IOHC."
Denis Marcellin-Little
Diplomate, American College of Veterinary Surgeons
Diplomate, American College of Veterinary Sports Medicine and Rehabilitation (Charter) Professor, Orthopedic Surgery
Chair, Department of Surgical & Radiological Sciences University of California, Davis
"I am very much looking forward to investigating the genetic roots of incomplete ossification of the humeral condyle (IOHC) in Boykin spaniels. IOHC unfortunately can have a profound negative impact on wellbeing and mobility in dogs. Our team, here at UC Davis, has expertise in genetics, in medical imaging, and in the analysis of bone geometry. We are very well positioned to investigate IOHC."
Denis Marcellin-Little
Diplomate, American College of Veterinary Surgeons
Diplomate, American College of Veterinary Sports Medicine and Rehabilitation (Charter) Professor, Orthopedic Surgery
Chair, Department of Surgical & Radiological Sciences University of California, Davis
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