ANZCVS 2011

Question 1

a) Discuss the role of steam sterilisation, ethylene oxide and hydrogen peroxide gas plasma in the sterilisation of surgical equipment. Include the conditions required for sterilisation and possible limitations of each of these methods.

Answer 1

• Steam sterilization: Most popular method of sterilization of surgical instruments in veterinary medicine. Sterilizes by denaturation and coagulation of proteins by heat. Gravity-displacement sterilizers are the most common models currently in use in Vet Med. Pre-vaccum units operate in a similar fashion but are faster since air is pumped out before the beginning of the cycle. Water acts a catalyst, hastening the process and allowing the use of lower temperatures, but must contact all instrument. Steam is lighter than cool air and raises, forcing cool air out of the bottom of the chamber. The required conditions for sterilization are 121 C for 30 min or 132C for 15 min followed by 30 min drying time. A “flash sterilization” (immediate use steam-sterilization – IUSS) can be used for metallic non-porous (no lumen) unwrapped instruments at 135C for 3 minutes, followed by 1 min drying time, but should only be used in emergency situations (i.e dropped instrument during surgery) and SHOULD NOT be used for implantable devices. Advantages: cost effective, efficacious against spores, non-toxic. Disadvantages: Instruments with concavities, such as bowls, must be placed with the opening facing down to avoid trapping cool air, potentially leading to sterilization failure.
• Ethylene Oxide: popularly used for temperature-sensitive equipment (i.e plastics, electronics); sterilizes by alkylation of proteins which obstructs cell metabolism and reproduction. Conditions: 1000mg/L, 65C, 85% humidity and 2 to 5 hours.
Advantages: readily diffuses through wrapping materials, safe on temperature-sensitive items
Disadvantages: EO is flammable and potentially toxic. May require EO emission abatement system to reduce environmental impact.
• Hydrogen Peroxide: Sterilizes via exposure of materials to hydroxyl and hydroperoxyl microbicidal free radicals. Advantages: Non-toxic, non-pollutant, rapid cycle (30-60 min). Disadvantage: relatively high cost of units; cannot be used for linens, liquids, powders or cellulose materials.

Question 2

b) Discuss the use of indicators for determining the effectiveness of sterilization. (8 marks)

Answer 2

Indicators are utilized to verify that the necessary conditions for sterilization have been met, and are typically process-specific. They do not guarantee sterility. The most common indicators are chemical strips, which are divided in 6 classes. The higher classes provide more parameter-specific information. The current recommendation is that a Type 1 indicator, such as sterilization tape, be placed on the outside of every surgical pack, and that an additional indicator be placed at the deepest part of the pack. Biological indicators are the best method to determine that the sterilization method was effective. Devices containing Geobacillus stearothermophilus are processed and cultured afterwards to verify inactivation (negative culture).

Question 3

a) Discuss the major factors that contribute to fracture non-union. (10 marks)

Answer 3

• Instability: Typically caused by poor technical judgement and/or execution on the part of the surgeon. Examples include the use of external coaptation in distal radial fractures, IM pins without added constraints against rotational and axial forces, ExFix with insufficient stiffness and loose cerclage wire.
• Poor biological environment: fracture location (small muscle envelope), extensiveness of soft tissue damage (high energy trauma) and surgical trauma may affect blood supply and prolong the debridement phase delaying healing.
• Nutrition: Adequate supply of protein, calcium, vitamin C and D are essential for bone healing and must derive from a well-balanced diet. Supplements are rarely indicated except for malnourished patents.

Question 4

b) List and describe the types of viable fracture non-unions based on radiographs. (6 marks)

Answer 4

• Vascular nonunion: characterized by cartilage and fibrous tissue formation within the fracture line. Radiographically characterized by a lucent line through the fracture observed on sequential radiographs.
• Hypertrophic nonunion: similar to vascular, but characterized by the presence of a prominent non-bridging callus.

Atrophic nonunions are not “viable” and thus do not meet the question. They are biologically inactive pseudoarthrosis. Radiographically they demonstrate no evidence of bone reaction and various degrees of bone sclerosis

Question 5

c) List and describe the properties of cancellous bone grafts that are beneficial in the treatment of fracture non-unions. (6 marks)

Answer 5

• Osteogenic property: synthesis of new bone from donor cells, which include MSC’s, osteoblasts and osteocytes.
• Osteoinductive property: MSC’s from donor site are recruited to produce chondroblasts and osteoblasts which produce new bone through endosteal ossification. The process is mediated by growth factors such as bone morphogenic proteins (BMP) ad platelet-derived growth factor (PDGF).
• Osteoconductive property: implanted scaffold passively allows ingrowth of host capillaries , perivascular tissue and MSC’s.

Question 6

d) Give three (3) examples of anatomical sites from which autogenous cancellous bone grafts are commonly harvested. (3 marks)

Answer 6

• Proximal humerus, distal to the greater tubercle
• Proximal tibia
• Ilial wing

Question 7

1. a) Name and describe the four (4) stages of acceptance of full-thickness free-
   skin grafts. (12 marks)

Answer 7

• Imbibition – first 24-48 hours, thin film of fibrin and plasma separate the graft from recipient site, providing oxygenation and nutrition (although precarious). After 48 hours a fine vascular network begins to form withing the fibrin layer.
• Inosculation – (day 2 to 3) capillary buds interface with the deep surface of the dermis and provide more robust oxygenation and nutrition.
• Revascularization – (day 3 to 7) new blood vessels either directly invade the graft or anastomose with to open dermal vascular channels, establishing a permanent vascular supply.

Question 8

2. b) Describe the factors that influence successful take of a full-thickness free- skin graft during wound bed preparation, the grafting procedure and the post- operative period. (13 marks)

Answer 8

• Wound bed preparation: The recipient ved must be free from debris, necrotic tissue, old/hypertrophic granulation and poorly vascularized tissue such as adipose. Bone, tendons, cartilage or nerve denuded of their fibrovascular connective tissue do not support grafts. A healthy granulation bed is ideal, and light debridement to assure direct contact between graft/vascular bed should be performed. The graft should be immobilized with sutures strategically placed to prevent motion but not excessively as to create ischemia.
• Grafting procedure: poorly vascularized tissue, such as adipose, must be adequately removed. The graft must be harvested as atraumatically as possible.
• Post-op care: strong and continuous contact between graft and recipient site is fundamental. Bandages are usually necessary,but should be carefully placed to avoid excessive compression. They should be well padded and bulky to limit limb motion. Vaccum-assisted devices are advisable if available. Fluid accumulation limits inosculation and revascularization, so a nonadherent hydrophilic bandage should be applied for the first 24-48 hours. Close monitoring for infection is very important. Bacteria such as B-hemolytic streptococci and pseudomonas secrete plasminogen activators and proteolytic enzymes which disrupt the fibrin seal preventing graft adhesion.

Question 9

a) Describe the gross anatomy of the salivary glands and ducts in both the dog and cat. (7 marks)

Answer 9

Dog

• Parotid gland – paired, large, triangular-shaped, located ventral to the horizontal ear canal. Closely associated with the maxillary vein, facial nerve and superficial temporal artery. Parotid duct opens on the parotid papilla adjacent to 104/204
• Mandibular gland – paired, large, oval shaped, located caudal and ventral to the parotid gland within a fibrous capsule at the confluence of the maxillary and linguofacial veins. Mandibular duct runs with the sublingual duct and opens on the floor of the mouth lateral and rostral to the lingual frenulum.
• Sublingual – smaller than the previous two, divided in monostomatic and polystomatic. The former originates in the rostroventral border of the mandibular gland and its duct runs with the mandibular duct, but opens in a separate papilla. The later is divided into several lobules along the mandibular duct and drain directly into the oral cavity.
• Zygomatic – irregular to ovoid-shaped, located on the floor of the orbit ventrocaudal to the eye and medial to the zygomatic arch. Has several dusts that open immediately caudal to the last molar.

Cat

• Same as dogs with the addition of a well-developed pair of molar salivary glands located caudomedial to the mandibular first molar. These are polystomatic mixed serous/mucoid glands.

Question 10

b) List the reasons for the high incidence of dehiscence in oesophageal wounds. (6 marks)

Answer 10

Factors that contribute to a higher risk of dehiscence include lack of a serosal layer, presence of saliva and food/water boluses and constant motion from head/neck motion and respiration.

Question 11

c) Briefly describe the different types of hiatal hernia. (6 marks)

Answer 11

• Sliding/axial hiatal hernias – characterized by laxity of the phrenicoesophageal ligaments, allowing gradual protrusion and dilation of the gastroesophageal junction into the thorax.
• Paraesophageal or rolling hiatal hernia – part of the gastric fundus herniates into the thoracic cavity
• Combination Sliding and paraesophageal hernia – combo laxity of phrenicoesophageal ligaments amd herniation of part of the gastric fundus
• Gastroesophageal intussusception – intussusception of the gastric cardia into the gastroesophageal junction

Question 12

d) Briefly explain the current theories regarding the pathogenesis of perianal
fistulas. (6 marks)

Answer 12

Currently believed to be a multifactorial immune-mediated disorder. Other theories include poor local conformation, crypt fecalith impaction and abscessation or spread of infection from anal sacs. Colitis and enteral triggers may initiate the disorder, which is complicated by abscessation of glands and hair follicles around the anus. Breeds with a higher density of perianal glands, like the German Shepherd, are thus more predisposed to the disorder.

Question 13

4. Answer all subparts of this question: Illustrate the anatomy of the major veins of the gastrointestinal tract, liver and spleen. You may use a diagram if you wish. (12 marks)

Answer 13

Question 14

b) List four (4) commonly reported types of congenital extrahepatic portosystemic vascular anomalies. (8 marks)

Answer 14

• Portal v. to Cd Vena Cava
• Portal v. to Azygous v.
• Left gastric to Cd Vena Cava
• Splenic V to Cd Vena Cava
• Cr Mesenteric to Cd Vena Cava
• Cd Mesenteric to Cr. Vena Cava
• Gastro-duodenal to Cd. Vena Cava

Question 15

c) Briefly describe the proposed aetiopathogenesis of multiple acquired portosystemic shunts. (5 marks)

Answer 15

Acquired PSS are believed to occur as a result of persistent portal hypertension leading to opening of vestigial fetal blood vessels. These are typically multiple, tortuous and extra-hepatic. Most connect a portal tributary to a renal vein or directly to the Cd Vena Cava adjacent to the kidneys. The most common causes of increased hydrostatic pressure are hepatic fibrosis, congenital non-cirrhotic portal hypertension and hepatic arteriovenous malformations.

Question 16

A 16-week-old kitten sustains a fracture of the distal femoral metaphysis
after minor trauma. History taking reveals the kitten is fed only minced beef.

i. Explain the likely aetiopathogenesis of the fracture in this patient.

Answer 16

This patient likely has Nutritional Secondary Hyperparathyroidism. The condition is induced by chronic feeding of a calcium-deficient/phosphorous rich diet leading to elevated parathormone levels. This hormone imcreases bone calcium resorption, leading to osteopenia and pathologic fractures.

Question 17

A 16-week-old kitten sustains a fracture of the distal femoral metaphysis after minor trauma. History taking reveals the kitten is fed only minced beef.

ii. Other than pathologic fractures, list three (3) radiographic changes that may be seen in the skeleton of this patient. (41⁄2 marks)

Answer 17

Generalized demineralization, characterized by decreased bone radiopacity; cortical thinning, widening of the medullary cavity.

Question 18

Describe the aetiopathogenesis of bone disease that may occur in a 13-year-old Australian terrier with chronic renal failure. (8 marks)

Answer 18

The condition is known as Renal Secondary Hyperparathyroidism, characterized by elevated parathormone levels (PTH) secondary to Chronic Renal Disease. PTH is naturally degraded and excreted by the kidneys, and its production is limited by calcitriol (negative feedback inhibition). Calcitriol, the active form of vitamin D, is produced by renal tubular cells. The relative deficiency of Calcitriol induced by renal disease leads to persistently high PTH, which increases calcium resorption from bone and leads to osteopenia.

Question 19

13-year-old Australian terrier with chronic renal failure. (8 marks)

iv. Name the most common location and radiographic features of bone disease in such a patient. (41⁄2 marks)

Answer 19

Bones of the skull and mandible are most commonly affected. Severe demineralization leads to softening to the point that the jaw is bendable (“rubber jaw”). Facial deformity, swelling and pain typically develop.

Question 20

Considering a non-ambulatory, five-year-old Dachshund with a Hansen type 1 disc extrusion at T13-L1:

1. a) Describe the expected findings of patellar reflex testing. (2 marks)

Answer 20

Patellar reflexes should be bilaterally hypereflexive, consistent with an UMN injury. The exception might be in the rare cases of spinal shock secondare to the concussive injury to the spinal cord caused by a high velocity disk extrusion. In this case the patellar reflexes may be hyporeflexive, mimicking a LMN injury. This may last hours to days and could lead the clinician to mistakenly diagnose a L4-S3 lesion. Thus the importance of MRI to confirm a diagnosis.

Question 21

Considering a non-ambulatory, five-year-old Dachshund with a Hansen type 1 disc extrusion at T13-L1:

2. b) Describe one (1) possible grading system of severity of neurologic dysfunction. (4 marks)

Answer 21

Griffiths Modified 5-Point scale

0: normal
1: Pain, not severe enough to result in neurologic disfunction
2: Paresis with or without pain; the degree of paresis or proprioceptive deficits become worse as disease becomes more severe
3: Plegia; total loss of voluntary movement in the affected limbs (and/or tail)
4: Plegia with loss of voluntary urinary function
5: Plegia with loss of voluntary urinary function AND loss of nociception in the affected limb (and /or tail)

Question 22

Considering a non-ambulatory, five-year-old Dachshund with a Hansen type 1 disc extrusion at T13-L1:

3. c) List the benefits and disadvantages of the different imaging modalities in this case; including plain radiographs, myelography, computed tomography and magnetic resonance imaging. (12 marks)

Answer 22

Plain radiographs: Readily available, images may be obtained without the use of general anesthesia (light sedation), good sensitivity of vertebral fractures, tumors and certain infection (diskospondylitis). Findings consistent with Type I IVDD may include narrowing of intervertebral spaces, narrowing of articular facets, narrowing and increased opacity of the intervertebral foramen, presence of mineralized disk material within the vertebral canal and vacuum phenomenon. Radiographic finding can be considered suggestive of thoracolumbar IVDD but are never diagnostic, with reported sensitivity for IVDD varying from 50 to 60%.
Myelography: Mostly replaced by CT/MRI nowadays but more sensitive for IVDE than plain radiographs. Requires general anesthesia/ Less expensive that MRI/CT. Lumbar die injection (L5-L6) is superior to cervical (although more difficult to perform) in the diagnosis of thoracolumbar IVDE. Can yield false-negative results in cases of lateral disk extrusion or extrusion into the intervertebral foramina. Myelogram is an invasive technique, and thus involves several risks. Those include worsening of neuro status, spinal cord trauma, and post-myelographic seizures (reported as high as 20% of cases). Reported diagnostic accuracy 70 to 99%, but less accurate than CT or MRI for lateralize lesions.
CT: Highly useful technique with may be performed without contrast, with IV contrast or with subarachnoid contrast. Requires 25 to 50% less contrast than conventional myelography, making it comparatively safer. More widely available than MRI, less costly and much faster. May be performed under sedation in many cases. Plain CT does not allow distinction between IVD annulus/nucleus or spinal cord/meninges/CSF, so IVDE is typically diagnosed based on the findings of hyperattenuating material withing the vertebral canal, loss of epidural fat and distortion of the spinal cord. Non-contrast CT is as diagnostic as myelography for IVDE in chondrodystrophic breeds, but the work-up must be completed with CT-myelogram or MRI if no lesions are found that explain the patient’s neurologic exam findings. More sensitive than conventional myelography for lateralized lesions.
MRI: Gold standard in IVDD imaging, producing the best soft tissue contrast among available imaging techniques (lowest risk of false-negative results as compared to previous techniques). Allows obtention of images in multiple planes without repositioning the patient. Myelography is not necessary (in contrast with CT) since tissue contrast can be manipulated with different acquisition sequences. Requires general anesthesia; study takes significantly more time that CT; MRI devices are more expensive and require more maintenance.

Question 23

Considering a non-ambulatory, five-year-old Dachshund with a Hansen type 1 disc extrusion at T13-L1:

4. d) List the indications for surgery. (4 marks)

Answer 23

• Severe hyperesthesia nonresponsive to medical management
• Moderate to severe neurologic deficits (paresis or plegia)
• Spinal cord compression identified on diagnostic imaging associated with above-mentioned clinical signs

Question 24

Considering a non-ambulatory, five-year-old Dachshund with a Hansen type 1 disc extrusion at T13-L1:

5. e) Identify the main clinical determinant of prognosis and explain how you would assess this. (3 marks)

Answer 24

Presence of nociception (“deep pain”) at the time of diagnosis. 80 to 95% of dogs with preserved nociception recover motor function within 2 weeks of surgery, as compared to 50% for those without preserved nociception. The previous notion that dogs who lost nociception for longer than 48 hours have a grave prognosis for return of normal function appears to be erroneous according to more recent reports. These dogs appear to have a similar prognosis top those who lost nociception within less than 48 hours. Only presence or absence of proprioception has been consistently associated with better or worse prognosis.

Question 25

Two distinct age populations of dog are affected by hip dysplasia (immature and adult animals).

1. a) Compare and contrast the clinical and diagnostic features of each group. (121⁄2 marks)

Answer 25

Juvenile hip dysplasia leads to clinical signs associated with discomfort due to joint cartilage loss and exposure of subchondral bone, as well as joint laxity leading to stretching of soft tissues. Clinical signs may include difficulty rising, exercise intolerance (most common sign), “bunny hopping”, intermittent or continuous lameness, muscle atrophy and a peculiar “waddling gait”. PE signs typically include discomfort during extension, external rotation and abduction of the hip, as well as poorly developed pelvic musculature. Diagnostically these patients present with various degrees of coxofemoral subluxation but few (if any) signs of joint degeneration early on. These cases eventually evolve into DJD. Cartilage loss is only observed via arthroscopy.
Adult-onset hip dysplasia leads to discomfort due to osteoarthritis, diagnostically characterized by coxofemoral bone sclerosis, periarticular osteophytosis and femoral neck/head remodeling. PE findings are similar to those of juvenile onset, except that joint laxity is rarely presence due to extensive periarticular fibrosis. Joint crepitus may be present.

Question 26

Two distinct age populations of dog are affected by hip dysplasia (immature and adult animals).

1. b) Discuss the various surgical treatment options for each group. Indicate at what age these treatments are applicable. (121⁄2 marks)

Answer 26

Surgical options for juvenile-onset hip dysplasia include juvenile pubic symphysiodesis (JPS), Pelvic osteotomy (double or triple – DPO / TPO), Total Hip Replacement (THR) and Femoral Neck and Head Ostectomy (FHNE).
JPS alters the growth of the pelvis and the degree of ventroversion of the acetabulum. It must be performed before 20 weeks of age in puppies with palpable and radiographic evidence of hip laxity. Risk of complications is low and a failure does not preclude the use of further procedures in the future.
Pelvic Osteotomy, whether double or triple, is performed with the intention of axially rotate and lateralize the acetabulum to improve femoral head coverage. Requires adequate screening and case selection. Good candidates are those with radiographic evidence of subluxation without degenerative changes, angle of reduction less than 30 deg and angle of sublux less than 10 deg, solid “feel” of reduction and minimal cartilage abnormalities (arthroscopy). Typically recommended for immature dogs (before completion of skeletal growth)
THR: Considered a salvage procedure to be used when medical management is no longer effective. Typically performed as late in life as possible due to limited useful life of implants (wear), but also occasionally considered for younger patients who do not tolerate medical management and require better function than what can be accomplished with FHNE. Highly advanced procedure, requiring a very experienced surgeon (referral). Costly.
FHNE: Also considered a salvage procedure to be used when medical management has failed or is not well tolerated. The procedure leads to the formation of a fibrous pseudoarthrosis, which is an inherently unstable “joint”. This makes the results somehow unpredictable when it comes to function, but pain is typically eliminated. Much less expensive and technically demanding that THR.

Question 27

A six-year-old, female-neutered Australian cattle dog presents with a 1cm diameter, poorly circumscribed, rapidly growing mass on the buccal gingiva of the mandible adjacent to the second molar on the left side. You are suspicious of a malignant neoplasm.

1. a) List your differential diagnoses for a malignant neoplasm in this location.

Answer 27

• Squamous Cell Carcinoma
• Intraosseous carcinoma
• Melanoma
• FSA
• HSA
• OSA
• CSA
• MLO (multilobular osteochondrosarcoma)
• MST
• TVT
• LSA
• Various odontogenic tumors are also possible, including odontogenic ameloblastoma (epithelial), odontogenic fibroma (mesenchymal), acanthomatous epulis (periodontal), ossifying epulis (periodontal), and fibromatous epulis (periodontal). These are benign tumors with features of malignancy, particularly local tissue destruction.

Question 28

A six-year-old, female-neutered Australian cattle dog presents with a 1cm diameter, poorly circumscribed, rapidly growing mass on the buccal gingiva of the mandible adjacent to the second molar on the left side. You are suspicious of a malignant neoplasm.

b) Describe how you would go about achieving a diagnosis and staging this tumour. (5 marks)

Answer 28

I would recommend incisional biopsy (wedge of center and periphery, but planning on minimizing contamination of normal tissue), radiographs of the affected area and thorax, regional lymph node aspirates and general bloodwork (CBC/Chem/UA). A CT of the affected area would also be recommended, particularly if radiographs reveal bone involvement. In that case I would also include a thoracic CT given its higher sensitivity for small lesions in comparison with radiographs.

Question 29

A six-year-old, female-neutered Australian cattle dog presents with a 1cm diameter, poorly circumscribed, rapidly growing mass on the buccal gingiva of the mandible adjacent to the second molar on the left side. You are suspicious of a malignant neoplasm.

Question 30

A six-year-old, female-neutered Australian cattle dog presents with a 1cm diameter, poorly circumscribed, rapidly growing mass on the buccal gingiva of the mandible adjacent to the second molar on the left side. You are suspicious of a malignant neoplasm.

c) You decide to attempt curative surgery. Outline the surgical technique you would perform. (5 marks)

Answer 30

The surgical technique will depend on the histological diagnosis, thus the need for good quality biopsies. Most oral malignancies, like MM, SCC, OSA, FSA and even acanthomatous epulis require wide surgical margins. This will almost always involve a hemimandibulectomy  for a tumor located adjacent to the second mandibular molar. 
Acanthomatous epulis (basal cell tumor) are nor classified as malignant but can be very aggressive at a local level.  Wide excision (rostral hemimandibulactomy) is still recommended given the high rate of recurrence with these tumors. The same is the case for ameloblastomas (osseous)

Question 31

A six-year-old, female-neutered Australian cattle dog presents with a 1cm diameter, poorly circumscribed, rapidly growing mass on the buccal gingiva of the mandible adjacent to the second molar on the left side. You are suspicious of a malignant neoplasm.

d) For each of the possible diagnoses you listed in question 3a) above, outline any adjunctive therapy you might consider. (5 marks)

3a:

• Squamous Cell Carcinoma
• Intraosseous carcinoma
• Melanoma
• FSA
• HSA
• OSA
• CSA
• MLO (multilobular osteochondrosarcoma)
• MST
• TVT
• LSA
• Various odontogenic tumors are also possible, including odontogenic ameloblastoma (epithelial), odontogenic fibroma (mesenchymal), acanthomatous epulis (periodontal), ossifying epulis (periodontal), and fibromatous epulis (periodontal). These are benign tumors with features of malignancy, particularly local tissue destruction.

Answer 31

• Squamous Cell Carcinoma (radiation therapy to “clean up” incomplete margins)
• Intraosseous carcinoma (radiation therapy to “clean up” incomplete margins)
• Melanoma (radiation therapy to “clean up” incomplete margins + melanoma vaccine)
• FSA (radiation therapy to “clean up” incomplete margins)
• HAS (radiation therapy to “clean up” incomplete margins)
• OSA (radiation therapy to “clean up” incomplete margins)
• CSA (radiation therapy to “clean up” incomplete margins)
• MLO (multilobular osteochondrosarcoma) (radiation therapy to “clean up” incomplete margins)
• MST (radiation therapy to “clean up” incomplete margins)
• TVT
• LSA (chemotherapy)
• Acanthomatous Epulis (not malignant, but included due to malignant behavior) - (radiation therapy to “clean up” incomplete margins. Possible intralesional chemo with bleomycin for recurrent lesions)

Question 32

A six-year-old, female-neutered Australian cattle dog presents with a 1cm diameter, poorly circumscribed, rapidly growing mass on the buccal gingiva of the mandible adjacent to the second molar on the left side. You are suspicious of a malignant neoplasm.

e) Explain how the prognosis for a tumour of the mandible differs from that of the maxilla. Provide a possible reason for this. (5 marks)

Answer 32

The prognosis for maxillary tumors is not as good as for those located in the mandible. This is likely because the maxilla contains many more vital structures (nerves, large vessels, sinuses, nasal cavity, etc…) which increases the morbidity with extensive surgery and limits the available margins. Dehiscence, recurrence and metastasis are more common with maxillary tumors.

Question 33

A 12-year-old, male-neutered German shepherd is presented after a protracted history of right-sided otitis externa that has been refractory to appropriate medical management.

a) List the surgical procedures that may be used to treat refractory otitis externa. (4 marks)

Answer 33

• Lateral ear canal resection
• Vertical ear canal ablation (with or without bulla osteotomy)
• Total ear canal resection (with or without bulla osteotomy)

Question 34

A 12-year-old, male-neutered German shepherd is presented after a protracted history of right-sided otitis externa that has been refractory to appropriate medical management.

b) Outline the clinical examination findings and diagnostic test results that would lead you to select each of the procedures you listed. (9 marks)

Answer 34

Lateral ear canal resection: Recurring episodes of otitis externa in patients who are difficult to medicate. Otitis must have been confirmed via cytology and possibly culture, and must have been treated unsuccessfully more than once to justify the procedure. Only to be considered to facilitate treatment in cases where the horizontal canal is minimally hyperplastic ad no neoplastic lesions are present. This procedure is NOT indicated for more chronic cases involving horizontal canal stenosis and otitis media unless combined with ventral bulla osteotomy.
Vertical canal Ablation: Chronic otitis externa must also have been confirmed via cytology and culture, and treatment must have been attempted without success. Adequate for cases of vertical canal hyperplasia with fairly normal horizontal canal but must be combined with ventral bulla osteotomy in cases of otitis media. Adequate for small neoplastic lesions affecting the vertical canal.
Total Ear Canal Ablasion: Indicated for chronic and severe cases of otitis externa that failed medical management and involve extensive hyperplasia and calcification. Adequate in lieu of Vertical canal ablation when the horizontal canal is also stenotic. Also adequate for treatment of neoplasia (ceruminous grand adenocarcinoma). Must be combined with ventral bulla osteotomy to allow drainage since most cases also involve otitis media.

Question 35

A 12-year-old, male-neutered German shepherd is presented after a protracted history of right-sided otitis externa that has been refractory to appropriate medical management.

c) List the possible complications of each procedure and briefly state how each complication can be avoided. (12 marks)

Answer 35

• Lateral ear canal resection and Vertical ear canal ablation: complications may include hair growth into the ear canal (avoided by the making of a “washboard” known as Zepp procedure), persistent or inadequate drainage and continuous otitis externa. Insufficient drainage is prevented by the creation of a large-enough stoma, particularly in the case of Vertical canal ablasion. Persistent otitis externa may be inevitable in cases of underlining dermatologic disease, and should be aggressively treated (medical management). Case selection and client education are fundamental, as these patients my often require a TECA later in life.
• Total Ear Canal Ablation: Multiple complications are possible and sometimes serious. These include infection, hemorrhage, ipsilateral head tilt, Facial nerve paralysis, Horner’s syndrome, abscessation, chronic fistulation and avascular necrosis of the pinna. These complications, particularly Facial nerve damage and Horner’s are more frequently observed in cats then in dogs. These complications can be minimized by gentle and minimal traction applied to the facial nerve, but may be present before surgery and must be adequately documented. Patients with facial nerve paralysis may develop dry eye and require frequent application of eye lubricant for several weeks. Ipsilateral head tilt may develop due to inner ear damage during curettage of the epitympanic recess and promontory of the tympanic cavity. This may last 2 to 3 weeks. Avascular necrosis of the pinna is caused by inadvertent occlusion of branches of the caudal auricular artery by sutures. This can be minimized by placing simple-interrupted sutures instead of simple-continuous or horizontal mattress.

Question 36

An eight-year-old, female chihuahua presents to you for respiratory stridor, non-
productive coughing and syncope. You are suspicious of tracheal collapse.

a) Describe your diagnostic evaluation of this case. (8 marks)

Answer 36

The diagnostic approach would start with a thorough physical evaluation, including thoracic and laryngeal auscultation and evaluation of the nostrils for stenosis. This would be followed by laryngoscopy/pharyngoscopy under sedation (very cautiously, well monitored and prepared for endotracheal intubation) to inspect the integrity and movement of the arytenoid cartilages and epiglottis, length of the soft palate, laryngeal saccules, as well as to rule out oral/pharyngeal/laryngeal foreign bodies and neoplasia. Cervical and thoracic radiographs would be performed to rule out extratracheal masses, pulmonary disease and hypoplastic trachea. Flexible endoscopy (tracheoscopy) should be used to evaluate the nasopharyngeal turbinates for aberrant turbinates and masses. It also allows the evaluation of the entire tracheobronchial tree and collection of samples for cytology and culture, as well as grading of collapse according to the degree of luminal loss. This is done as the scope is gradually retracted from the carina.
General blood count, biochemistry and UA performed as pre-surgical routine.

Question 37

An eight-year-old, female chihuahua presents to you for respiratory stridor, non-
productive coughing and syncope. You are suspicious of tracheal collapse.

b) Outline the grading system commonly used for tracheal collapse.

Answer 37

Grade 1 -Normal tracheal anatomy; Redundant dorsal tracheal membrane occludes lumen by 25%
Grade 2 – Mild to moderate flattening of tracheal cartilages; 50 % loss of luminal diameter
Grade 3 – Severe flattening of tracheal cartilages; 75% loss of luminal diameter
Grade 4 – Complete obstruction; tracheal lumen is obliterated

Question 38

An eight-year-old, female chihuahua presents to you for respiratory stridor, non-
productive coughing and syncope. You are suspicious of tracheal collapse.

c) Outline your treatment options for a case of tracheal collapse. (8 marks)

Answer 38

Treatment options include medical and surgical approaches. Medical management is recommended for cases of < 50% loss of luminal diameter (Grade 2) or for those with medical issues not expected to improve with surgery (concomitant pulmonary, laryngeal or cardia disease). Medical management may include antitussives (hydrocodone bitartrate, butorphanol tartrate), antibiotics (ampicillin, cefazolin, clindamycin), bronchodilators (theophylline, aminophylline, albuterol), anti-inflammatories (prednisone) and sedatives (acepromazine).
Surgical options are reserved for grades 2 or higher (>50% luminal diameter loss) that are refractory to medical management; surgical techniques are geared towards supporting the tracheal rings and trachealis muscle via the use of extratracheal ring prosthesis or endotracheal stents.

Question 39

An eight-year-old, female chihuahua presents to you for respiratory stridor, non-
productive coughing and syncope. You are suspicious of tracheal collapse.

d) List the possible complications of surgery for tracheal collapse.

Answer 39

Extratracheal prosthetic ring application may lead to damage to tracheal vasculature and innervation (Recurrent laryngeal nerves) during application, leading to tracheal necrosis and laryngeal paresis/paralysis respectively. Infection deriving from penetration of the tracheal lumen; Improperly aerated EO sterilized prosthesis (syringe case rings) can lead to extensive tissue reaction; These complications may be lethal.
Endotracheal prosthesis may be incorrectly placed or sized, leading to death. Too small implants may migrate, while too large implants may lead to tracheal necrosis. Stents too close to the larynx may lead to intractable laryngospasm. Granulomas may develop in 20 to 30% of cases and require management with steroids. Persistent cough, pneumothorax, emphysema, infection, mucous obstruction, tracheal rupture, ulceration of the tracheal epithelium, implant fracture, implant collapse or deformation.
The overall complication rate for extratracheal Vs endotracheal methods is similar, around 42% to 43%

Question 40

A seven-month-old female-neutered labrador retriever presents to you for urinary incontinence. The owners describe constant urine dripping as the dog walks around although it will void small amounts of urine. You are suspicious of an ectopic ureter.

1. a) List three (3) other differential diagnoses for this case. (3 marks)

Answer 40

Hormonal-responsive (post-spay) incontinence
Lower or Upper motor neuron disorders or reflex dyssynergia
Urge Incontinence (inflammation or infection)
Anatomic outflow obstruction (paradoxic incontinence)
Behavioral incontinence (submissiveness)

Question 41

A seven-month-old female-neutered labrador retriever presents to you for urinary incontinence. The owners describe constant urine dripping as the dog walks around although it will void small amounts of urine. You are suspicious of an ectopic ureter.

2. b) Outline the options for diagnostic evaluation of this case. Indicate which test is considered the most reliable for diagnosing ectopic ureters in females dogs. (10 marks)

Answer 41

Diagnostic options include abdominal radiography, ultrasound and cystoscopy. Radiography can be combined with the use of contrasts (excretory urography) to evaluate the location of ureteral opening as well as other urogenital abnormalities (hydronephrosis, hydroureter, hypoplastic bladder and ureteroceles). This can be preceeded by a pneumocystogram to facilitate visualization of the ureters when filled with contrast. Ultrasonography can detect the presence of ectopic ureter, but is highly examiner dependent. Cystoscopy is a reliable, sensitive and specific method to diagnose ectopic ureters. It allows inspection of the bladder, urethra, vaginal tract and uretus.
CT excretory urography is the most sensitive, reliable and specific method to diagnose ectopic ureters. It is considered the diagnostic modality of choice whenever available.

Question 42

A seven-month-old female-neutered labrador retriever presents to you for urinary incontinence. The owners describe constant urine dripping as the dog walks around although it will void small amounts of urine. You are suspicious of an ectopic ureter.

3. c) Testing demonstrates an intramural ectopic ureter on the left side. Describe the surgery you would perform in this case. (8 marks)

Answer 42

Neoureterostomy: An incision is performed on the ventral aspect of the bladder, as close possible to the beginning of the urethra. Stay sutures are used to stabilize the bladder and avoid tissue trauma. The urethra is temporarily occluded to cause ureteral distension. The distended ureteral ridge is identified and incised using #11 or #15 scalpel blade for 4 to 5 mm. The ureteral mucosa is sutured to the bladder mucosa 360 deg using simple-interrupted 5-0 to 7-0 absorbable suture material (poliglecaprone 25). A 3.5 to 5 Fr catheter is introduced into the remaining distal ureter and two simple interrupted sutures (4-0 polypropilene) are pre-placed (not yet tied) from the serosal surface, including the ureteral mucosa 360 deg around the catheter but not penetrating the bladder mucosa. The catheter is removed and the sutures are tied to permanently occlude the remaining ectopic ureter. The bladder and abdominal wall are closed in standard fashion.

Question 43

A seven-month-old female-neutered labrador retriever presents to you for urinary incontinence. The owners describe constant urine dripping as the dog walks around although it will void small amounts of urine. You are suspicious of an ectopic ureter.

4. d) Indicate the published success rate for surgery alone in resolving the incontinence in ectopic ureters. (2 marks)

Answer 43

Previous reports indicated that as few as 30% of dogs will be fully continent after surgery. More recent reports (2012) indicated that 72% of surgically-corrected cases were fully continent.

Question 44

A seven-month-old female-neutered labrador retriever presents to you for urinary incontinence. The owners describe constant urine dripping as the dog walks around although it will void small amounts of urine. You are suspicious of an ectopic ureter.

5. e) Name a minimally invasive option that has been described for treating intramural ectopic ureters. (2 marks)

Answer 44

Cystoscopically-guided laser ablation.