Cases

GRACE KAEMPERBVScV student INTRODUCTION Hemipelvectomy is a surgical procedure involving removal of the hemipelvis and corresponding hindlimb.  It can be classified as total or subtotal, where subtotal has three further subtypes: mid-to-cranial, mid-to-caudal and caudal (Barbur et al. 2015). There is a paucity of veterinary literature detailing both technical and clinical aspects of hemipelvectomy.  One study presents hemipelvectomies as “complex, aggressive surgical procedures” with a high risk of intraoperative complications and “a slower return to ambulation than amputation” (Kramer et al. 2008).  There is a need to challenge this commonly held perception in the veterinary industry, and the purpose of this case report is to present hemipelvectomy as a viable treatment option for a range of otherwise inaccessible tumours. This case study examines three dogs that underwent hemipelvectomy in 2018 at a single veterinary specialist hospital in Auckland.  Two dogs presented with osteosarcoma of the proximal femur and ilium respectively, and the third was diagnosed with a peripheral nerve sheath tumour (PNST) of the sciatic nerve.  In all three cases, the location of the tumour rendered standard limb amputation (coxofemoral disarticulation) insufficient for primary tumour control.  Therefore, a hemipelvectomy was required to obtain appropriate surgical margins. All dogs were followed from diagnosis and surgery, through to recovery, to examine both the oncologic and functional outcomes.  See Table 1 for a summary of the three cases. HEMIPELVECTOMY PROCEDURE   Anaesthesia protocols were determined at the discretion of the surgeon (two surgeons performed three surgeries).  A similar anaesthesia protocol was used in all three cases.  Dogs were pre-medicated I/V with 3 µg/kg fentanyl (Fentanyl Citrate Injection 500µg; Hospira New Zealand Ltd, Auckland, NZ) or 3 µg/kg remifentanil (ULTIVA; Pharmacy Retailing Ltd, Auckland, NZ), which was followed by anaesthetic induction using I/V 0.25 mg/kg diazepam (Ilium Diazepam; Ethical Agents Ltd, Auckland, NZ) and propofol (Fresofol 1%; Fresenius Kabi, Auckland, NZ) to effect.  A constant rate I/V infusion (CRI) of lidocaine (Lopaine 2%, Ethical Agents Ltd, Auckland, NZ), ketamine (Ketaset 10%, Zoetis New Zealand Ltd, Auckland, NZ) and fentanyl/remifentanil (depending on the pre-medication) and I/V fluid therapy with lactated Ringer’s solution at 10 mL/kg were given for the duration of the procedure and recovery.  In two cases, 0.1 mg/kg morphine (DBL Morphine Sulphate 5 mg/mL Injection, Hospira) was given epidurally for additional analgesia.   The dogs were placed in lateral recumbency with a hanging leg preparation and an anal purse string suture was placed.  The surgical technique for all three cases was similar and based on the hemipelvectomy method described by Barbur et al. (2015).  A ventral approach was initially used with elevation of the sartorius, pectineus, gracilis, and adductor magnes et brevis muscles from their origin.  This allowed isolation, ligation, and transection of the femoral artery and vein, and the obturator nerve.  Pubic and ischial osteotomies were performed.  Further muscle elevations exposed the ventral aspect of the sacroiliac joint, which was then disarticulated.  The limb was then adducted, and the approach changed to dorsal.  The sciatic nerve was isolated and transected.  The ilium was freed by elevating its muscle and soft tissue attachments.  The sacrotuberous ligament and dorsal sacroiliac ligament were incised to free the ilium from the sacrum and to allow removal of the hemipelvis and ipsilateral limb.  The pelvic diaphragm was reconstructed during closure by approximating the remaining musculature.  The subcutaneous tissue and skin were closed routinely to minimise tension (Barbur et al. 2015).  A Jackson Pratt drain was placed before closure.  All resected tissues were submitted for histopathology.   Any differences peculiar to the individual cases are discussed below. CASE ONE A 13-year-old, female, spayed Labrador Retriever presented with acute left hindlimb lameness of 10 days’ duration.  Radiographs revealed a pathological fracture of the proximal left femur with suspected neoplastic involvement of the ipsilateral coxofemoral joint.  Thoracic radiographs showed a 5 mm-diameter, rounded, soft-tissue nodule in the caudodorsal aspect of the right caudal lung lobe.  Definitive tissue sampling of the pulmonary nodule was not obtained, and both benign and malignant considerations were given during clinical decision making.  An abdominal ultrasound identified a bilobed, diffusely heterogenous, soft-tissue mass of 31 mmx 12 mm effacing the left adrenal gland, and mild left medial iliac lymphadenopathy.  Preoperative biopsy of the fracture site was not pursued, as treatment was with palliative intent. A subtotal mid-to-cranial hemipelvectomy with concurrent amputation of the left pelvic limb was performed, utilising an osteotomy of the ilium caudal to the sacrum, osteotomy of the pubis within the obturator foramen, and osteotomy of the cranial ischium.  Soft tissue dissection was performed outside the muscular compartment containing the fracture, such that the fracture haematoma and tumour were not encountered during surgery.  Haemostasis was achieved with an electrothermal vessel sealing device (Ligasure; Medtronic Corporate ANZ, Auckland, NZ) and no complications arose during surgery. Fig.1 Dorsoventral radiograph of the pelvis of a Labrador Retriever taken 10 weeks after hemipelvectomy surgery as palliative treatment for osteosarcoma of the left proximal femur and acetabulum.  There is an aggressive monostotic lesion of the right ischium with motheaten lysis, heterogenous sclerosis and irregular periosteal new bone formation. Histopathology identified the proximal femoral/acetabular malignancy as an osteosarcoma with haemorrhage and necrosis.  Surgical margin assessment revealed no neoplastic cells within 40 mm of the inked margins. The dog was strongly ambulatory following surgery and was discharged from hospital the day following her hemipelvectomy.  The functional outcome, as reported by the owner, was excellent for 10 weeks after surgery.  At that time, the dog developed acute non-ambulatory paresis and urinary incontinence.  Neurologic examination was consistent with a painful L7-S3 lesion.  Radiographs revealed motheaten lysis and heterogeneous sclerosis of the right ischium, and further pulmonary nodules (Figure 1).  Advanced imaging and tissue biopsy were declined, but distant metastasis (spine and lungs) was suspected.  The dog was discharged with analgesia provided by 400 mg gabapentin (Neurontin; Pfizer New Zealand, Auckland, NZ) and 37.5 mg carprofen (Rimadyl; Zoetis New Zealand Ltd, Auckland, NZ) both given orally twice daily, but was euthanised due to lack of clinical improvement. CASE TWO An 11-year-old, male, neutered

When Maggie’s mum noticed she wasn’t eating and slept in longer than usual one Sunday morning, she knew something was wrong and brought her in to VS A&E. Maggie is no stranger to us at VSA and we know how much she loves food, so even though she looked fine on the outside, her history of dietary indiscretion, oesophageal foreign bodies, ureteral obstructions and chronic kidney disease had us wondering what was happening inside. Little did we know at the time she would become a very complex case.

The most common cause of front leg lameness in the dog is developmental problems of the elbow joint. This disease leads to degenerative changes (osteoarthritis) in the joint including carti- lage damage, bone spur (osteophyte) pro- duction, and loose bone fragments. ELBOW JOINT FUNCTION The elbow joint of the dog is formed by three bones (the humerus, ra- dius and ulna bones {Figure 1}) that must fit together correctly for the joint to func- tion normally. There are ligaments on the inside and outside of the elbow to main- tain stability. Although the elbow joints of dogs and humans have similar anatomy, the forces applied to the dog’s elbow are different because dogs stand on their front legs. The humerus bone should glide smoothly around the C-shaped curve formed by the radius and ulna bones. CAUSES OF ELBOW DYSPLASIA Elbow dysplasia is typically a developmental, inherited disease of young large -breed dogs. In some dogs, during growth, a step develops in the C-shape between the radius and ulna bones possibly due to the radius bone being too short or too long relative to the ulna.  This causes extra stress to be placed on prominent parts of the ulna bone (the anconeal or coronoid processes {Figure 2}) or the cartilage of the humerus. Cracks can then occur in the bone across the lines of greatest stress or the bone fails to grow normally. The joint cartilage may also be damaged in this process. Arthritis develops as a result of the damage to the bone and the cartilage. There are three main forms of elbow dys- plasia that cause pain and arthritis: Fragmented coronoid process (FCP). A crack occurs in this triangular- shaped bony bulge on the inside edge of the ulna bone. Ununited anconeal process (UAP). A lack of normal bone growth re- sults in this bone fragment becoming loose at the top of the ulna bone. Osteochondritis of the humerus (OCD). A flap of loose cartilage develops on the inside surface of the humerus bone. SYMPTONS Typically, affected dogs show front leg lameness that can start as young as 5 months of age. The lameness may be in- termittent and tends to improve with rest and get worse with exercise. Not all dogs with elbow dysplasia show symptoms. DIAGNOSIS A thorough orthopaedic and neuro- logic examination is performed evaluating the dog when walking and by manipulating all four limbs and the spine. Swelling, pain, and joint stiffness can frequently be felt in the affected elbow. Sedation or anaesthe- sia and X-rays are necessary to show signs of arthritis and to assess the bone structure. A CT scan will often be more effective in showing any bony changes. MEDICAL TREATMENT Some dogs with confirmed elbow dysplasia will improve without surgery. The object of medical treatment is to control the symptoms. The dog should not be allowed to get overweight and ex- ercise should be controlled. Cartilage- protecting agents (omega fatty acids, glu- cosamine, green-lipped mussel, fish oil) may help lubricate the joint and keep cartilage healthy. Generally, lifelong supplementation is necessary. Anti-inflammatory medication (aspirin-like drugs) can be helpful in reducing pain but should only be necessary occasionally. Medical treatment does not stop arthritis from continuing to develop. SURGERY Other dogs with elbow dysplasia benefit from surgery depending on the type of damage and arthritis. The type of surgery differs from dog to dog and may involve passing a small telescope (arthroscope) into the joint to see if a step is present between the radius and ulna bones. Loose bone fragments may then be removed or stabilized using a bone screw. (Figure 3) The ulna bone may be cut to remove the step and a pin may be placed to help healing. (Figure 4) RESULTS Dogs that have had surgery generally show excellent results with some progression of arthritis, few complications and normal function. If the ulna bone is cut, healing takes about 2-3 months and most dogs can return to full activity 4-5 months after surgery. Be sure to check out our article on post operative care for dogs with elbow dysplasia for best results post operation.

Pebbles was an active four-year-old German Shepard with a passion for chasing seagulls on the beach. Even though the seagulls would fly away before she caught them, her enthusiasm for her game never wavered. Over a period, Pebbles started to show less enthusiasm for her chase, often choosing to sit and watch instead. One day after a visit to the beach, her owners noticed her limping. Thinking it was because she had pulled something, they kept her quiet at home for a few days in the hope that it would clear up. After several days with no improvement, they took her to their local vet where she was prescribed anti-inflammatories. Pebbles showed no noticeable improvement on the medication, so she returned to the vet who referred her to us for further examination. Once here, we did some x-rays to determine what was happening. Her x-rays showed Pebbles had hip dysplasia in both hips, with her left being the worst. Once we talked with her owners, they said it explained a lot of her recent behaviour. She did not like going outside as much anymore, nor would she follow them in the garden. Instead, she returned to the house and slept. With uncontrolled pain restricting her quality of life, her owners knew she could not continue as she was. Fig.1 Initial radiographs/x-rays of Pebbles’ hips showing arthritis in both joints. To treat Pebbles, we had the options of prescribing anti-inflammatory medication for the rest of her life, which was not very successful at reducing her pain, commiting to long-term lifestyle adjustment or physiotherapy programme, or a hip surgery. Her family decided that a left hip replacement would be the best treatment for Pebbles, even though they were anxious about the risks and complications of hip replacement surgery. The surgery went fine and to help her recover, Pebbles was confined to a cage for the next 12 weeks. After a final check, Pebbles could resume her normal daily activities. Her owners noticed an almost instant change in their dog. She went from being a reclusive and depressed “older” girl to an enthusiastic adult puppy who once again enjoyed chasing her beloved seagulls. A few months later, her owners noticed she was slowing down again. Pebbles showed signs of being depressed and was this time limping on her right leg. They returned here and we took further x-rays of Pebbles. This time they showed her right hip needed a replacement, so her owners decided to have this done one year after her left hip was replaced. Once again, surgery was successful. Unfortunately, when Pebbles returned to have her sutures removed, she fractured her femur on her right leg while walking outside in the carpark. Miraculously, the fracture did not involve the prosthetic hip. We repaired the fracture with a plate and Pebbles recovered as predicted. Fig.2 & 3 Radiograph/x-ray showing both hip replacements, but also the break in the right femur. Hip replacement surgery does have a 20-30% risk of complications. Some of these complications are severe, such as a fractured femur which happened to Pebble. However most of the complications can be fixed and result in a normal active life for the animal afterwards. Pebbles’ life has changed dramatically since her surgeries. Instead of being left to a life of poorly managed pain and a young dog who would rather sleep than do anything else, they have a dog which shows obvious enjoyment of life. Pebbles runs, plays and chases seagulls as much as she ever did, in a life free from pain and regular medications. DR ALASTAIR COOMER Director & Registered Specialist Small Animal Surgery  alastair.coomer@vsnz.co.nz Alastair graduated from Massey University with a Bachelor of Veterinary Science in 2003, and worked in mixed animal practice in Ashburton for 18… READ MORE… Share on facebook Facebook Share on twitter Twitter Share on linkedin LinkedIn