Breeds – Generally medium to large dogs are affected
Gender – No gender predilection
Age – Middle aged to older
Etiology - Many neoplasms of the pelvis are metastatic lesions, but multiple myeloma, chondrosarcoma, and osteosarcoma should be considered. Neoplasia of the pelvis is rare
Dogs have progressive lameness, and may be lethargic, inappetent, and depressed in the later stages. In addition, they may stand in a position with a roached back in an attempt to shift weight to the forelimbs.
Lameness, swelling of the affected area, and pain on palpation may be found.
Radiographs generally show proliferative/lytic lesions of the affected area. A CT is recommended to determine the extent and if resection is possible.
The patient should be thoroughly evaluated for the presence of metastatic disease. If a discrete lesion is found, such as a primary bone tumor, a hemipelvectomy may be performed. Depending on the extent, amputation of the affected limb may be necessary. If the cranial ilium or caudal ischium is involved, it may be possible to spare the limb depending on the invasiveness of the disease. Caution is advised before undertaking this magnitude of surgery because of the real possibility of metastases already occurring and orthopedic conditions of the remaining limbs. Follow-up adjunctive treatment, such as chemotherapy or radiation therapy, is usually recommended.
Breeds – Any breed
Gender – No gender predilection, although intact males and females seem to be disproportionately affected
Age – Any age
Etiology – Trauma. Many cases occur as a result of automobile trauma. Because of this and the fact that there is significant trauma, careful evaluation of the thoracic structures is important to detect cardiac arrhythmias, pneumothorax, pulmonary edema, or diaphragmatic hernia, and careful evaluation of the abdomen, including damage to the liver or spleen resulting in hemoabdomen, or damage to the urinary system, especially the bladder, resulting in uroabdomen. Careful attention should be paid to the neurologic system, especially if sacral fractures or fractures of the cranial ischium are present. In addition, dogs may have an abdominal wall hernia.
Often owners witness trauma, such as hit by automobile, or another sudden traumatic event that results in sudden onset of severe lameness of the pelvic limb(s).
Fractures of the pelvis result in lameness, pain on manipulation, and crepitation during manipulation of the limb. If the lumbosacral trunk or sciatic nerves are involved, lower motor neuron signs may be present in the affected limb. The presence or absence of deep pain sensation should be noted, along with tail tone, anal sphincter reflex, and the condition of the urinary bladder.
Radiographs are generally diagnostic, but may underrepresent the severity of the trauma. A CT evaluation may give additional details, especially if the sacrum or medial wall of the acetabulum is affected. Because the pelvis has a box-like structure, at least 2 fractures, and usually 3, are present, so careful scrutiny should be applied.
Most fractures of the pelvis require internal fixation to restore anatomy and function. If fractures of only the pubis and ischium are involved, these may be managed with strict cage rest and assisted walking with a sling for 4 weeks.
Sacroiliac luxations/fractures, fractures of the ilial body, and acetabular fractures all contribute to the weight bearing axis and transmit weight bearing forces from the limb to the spinal column. Therefore, they generally require internal fixation. Exceptions include minimally diplaced sacroiliac luxations with minimal pain or lameness in smaller dogs, minimally displaced ilial body fractures in young dogs, and fractures of the caudal 1/3 of the acetabulum in smaller dogs. These injuries may often be managed with cage rest and sling support for 1 month.
Clinically significant sacroiliac luxations or fractures should be managed with 1 or 2 screws placed through the ilium into the sacral body. If a fracture is present, the patient should be carefully evaluated for damage to the lumbsacral trunk and the associated nerves, especially those that contribute to fecal and urinary continence, as well as sciatic nerve dysfunction. Neurologic damage with S-I luxations is less common.
Fractures of the body of the ilium should be repaired with a bone plate and screws. Careful contour of the plate will allow the collapsed caudal portion of the pelvis to be pulled out to avoid issues with defecation. Also, restoring normal anatomy of the ilium helps to pull other fractures of the pubis and ischium into better alignment.
Fractures of the acetabulum should be repaired because they are part of the weight bearing axis of the pelvic limb and because they involve a major joint. Repair techniques include a curved bone plate and screws applied to the dorsal rim of the acetabulum. Careful apposition and alignment are critical to restore normal joint anatomy. The approach to the acetabulum usually includes an osteotomy of the greater trochanter to have access to the joint under the gluteal muscles, and therefore requires repair in the form of a pin and tension band when closing. As mentioned above, caudal acetabular fractures of smaller dogs may be managed conservatively with an Ehmer or similar non weight bearing sling. However, arthritis will develop. If the fracture is in more than 4 pieces or the medial supporting wall of the acetabulum is compromised, a femoral head and neck excision may be performed.
Post operative care consists of cage rest and sling walking for 1 month to allow the other fractures of the pubis and ischium to heal, as well as the primary repairs. If the dog is an intact female, ovariohysterectomy should be considered, or if the dog is a breeding animal, a C section should be planned to deliver puppies.