Mature lame animal 2 Flashcards
What is the most common primary bone tumour?
Waht are the predilection sites of this neoplasia?
What dogs are predisposed to this?
- The most common primary tumour is the osteosarcoma accounting for up to 80% of bone tumours
- The osteosarcoma has predilection sites-proximal humerus and distal radius and proximal tibia and distal femur
- These tumours fail to cross the joint
- They will have metastasised to the lungs by the time of diagnosis
- Giant and large breeds with average ages of 5-8 years are predisposed
What are the clinical signs of bone neoplasia?
- Insidious and poorly responsive to analgesia
- Moderate to marked pain on palpation of the tumour site
- May be accompanied by marked muscle atrophy
- Moderate to marked soft tissue swelling
- There may be an acute deterioration when the weakened bone fractures. This is termed a pathological fracture
- The pathological fracture often occurs with minimal trauma
- Always consider this when an older dog has fractured a limb with no or little history of trauma
How is neoplasia of the bones diagnosed?
What are the key things to remember?
- clinical signs and history are suggestive
- Radiography- this may show both a proliferative and destructive pattern (see radiographic interpretation MSK diagnostics practical)
- The initial changes of the osteosarcoma occur on the endosteal surface
Always radiograph the chest (three views are advised - DV, left and right lateral)
Mets need to be 4mm in size to see on radiograph)
CT is a more sensitive way to look for chest metastases
How is a histological diagnosis made of a bone neoplasia?
Histological diagnosis is needed to determine ig it is a primary or secondary neoplasia, and is important for surgical or medical mangement
* This is achieved with core biopsies obtained with a Jamshidi needle
* Radiography confirms correct placement of the needle
* Biopsies should be taken from the centre of the lesion (the periphery may contain reactive bone only)
How do you use a jamshidi needle?
The needles are also designed for bone marrow aspiration
The stylet is removed when entering the bone to harvest a core
Vigorous twisting and rocking breaks the core from the bone
The stylet is used to push the core
from the free end of the needle and the core is placed in formal saline
Several biopsies are taken to increase the diagnostic yield
What is the treatment options for osteosarcomas?
It is important that the owner is aware that it is unlikely, that the treatment will be curative
- Limb amputation offers immediate pain relief - Amputation is better tolerated in the hind limb and in smaller dogs
- Limb sparing procedures are available with the placement of an auto or allograft having excised the tumour
- Limb amputation can also be followed by the placement of an endoprosthesis
- All surgical treatments can be followed up by chemotherapy e.g. carboplatin
Some clients will opt for medical management which is primarily analgesia- bisphosphonates are particularly useful in this situation (osteoclast inhibitors)
What is the prognosis for osteoscrcomas in the dog ?
- The prognosis for appendicular osteosarcoma in the dog is generally poor with lung metastasis being the usual outcome and cause of death.
- Average survival times without treatment are often less than one month
- With limb amputation alone the median survival time is 4-5 months
- With amputation or limb sparing techniques followed by neoadjuvant chemotherapy survival times of 9-10 months have been reported
The prognosis for other tumour types is variable
What is the prognosis for osteosarcoma in the cat?
more favorable prognosis then in the dog. If there is no evidence of metastatic disease then no follow up chemotherapy is advised and median survival times range from 24-44 months
Where do nerve root tumours originate from?
Where do they occur?
What is the clinical presentation?
How are they able to be detected on clinical exam?
- Nerve root tumours arise from the connective tissue around the nerve, a neurofibroma or sarcoma or the schwann cells, a schwannoma
- They can occur in the brachial and lumbosacral plexuses
- They are rare tumours of the older dog c.8 years old
- Rarer in the cat
- Chronic and insidious in their nature
- Painful
- Marked muscle atrophy usually in one limb (a monoparesis) as there is neurogenic as well as disuse atrophy
- Careful palpation of the axilla and rectal examination may detect their presence
how are nerve root tumours diagnosed?
MRI is the imaging modality of choice although radiography with contrast (myelography) and
CT can also be used
What is the treatment for nerve root tumours?
What is the prognosis?
- Surgical resection but this can be difficult and limb amputation is often employed to remove the tumour
- Significant neurological deficits can result from the surgery if the limb is spared
- The tumour may extend into the spinal canal making full excision, even with a laminectomy difficult
- Recurrence is common following incomplete surgical excision
- Adjuvant chemotherapy can be employed or radiotherapy
- The prognosis is guarded and recurrence within one year is likely
- This is a local disease and rarely spreads to other sites
What is the signalment of cruciate rupture in the cat?
What is the treatment?
- Usually obese
- Minimal trauma
- Mineralisation of intra-articular findings may be insignificant
- Extra articular stabilisation but generally improve with rest only
- TTA and TPLO have been performed
What does PADS in the cat stand for?
What is this condition?
How is this treated?
What is the long term impact of these cats?
Patella fracture and dental anomaly syndrome
* Patella fractures in the cat
* Associated with retained deciduous teeth and a variety of other typical fractures
* Familial tendency occurring in young cats often with little or no history of trauma
* They are unable to fix the stifle ( looks like a femoral neuropathy, will collapse on back end)
Treatment
* Various attempts to get the patella to heal have been shown to fail
* Soft tissue suturing will often be enough to produce a functional repair
* If the patella has marked distraction (very displaced) then try and secure patella closer to normal position)
- Most of these fractures result in a functional outcome irrespective of the treatment
- Beware bilateral disease
- Associated with fractures in other bones e.g. humerus, tibia and ischium. These occur later in the cats life (c. 8 years)
How do you diagnose a fracture/seperation of femoral head physis (salter harris type I)?
What is the treatment for this?
- Usually animals are 6-7 months old
- Epiphysis remains in the acetabulum attached by the teres ligament
- Often minimally displaced – always take a “frog-leg” view
If accute the try and surgically repair - Stabilised with 2-3 K-wires or a lag screw
If chronic then - then Femoral Head and Neck Excision or total hip replacement
What is the typical histrory of the animal with joint disease?
- Chronic lameness
- Worse in the morning or after rising particularly after exercising
- Possible association with colder weather?
- Swelling to joints
- Reluctant to mount stairs/jump into cars
- Previous tick exposure or foreign travel?
The cat shows less obvious signs but these include
* Reluctance to jump onto work surfaces
* Failure to groom
* Stiffness on rising
* Reduced activity levels
what are the clinicla signs of joint disease?
- Walking stiffly
- Lameness in one or several limbs
- Joints swollen either as a result of effusion or periarticular fibrosis
- Pain on manipulation
- Reduced range of movement
- Muscle atrophy
- Any systemic signs? e.g. pyrexia, general malaise - lyme disease
If you have taped a joint and have a negative culture, what should you do next if you think the joint is septics>
Arthrotomy
Obtain a synovial biopsy and then grow from this
what are the different causes of athritis?
Primary arthritis is rare - Hereditary predisposition and no underlying cause is identified
Secondary arthritis very common:
* Developmental conditions e.g. elbow and hip dysplasia, osteochondrosis, patella luxation
* Degenerative conditions e.g. cruciate disease
* Inflammatory arthropathies e.g. rheumatoid arthritis, systemic lupus etc.
* Trauma
* Sepsis
* Crystal induced- this is very uncommon in the dog and cat
What is the pathophysiology of osteoarthritis?
- Weight bearing areas of the joint undergo fibrillation (fraying) of the articular cartilage
- This results in exposure of the subchondral bone to synovial fluid which then scleroses and produces osteophytes and resulting joint re-modelling
- Loss of the articular cartilage results in eburnation of the underlying bone
- All these processes are mediated by an array of synovial, chondrocytic, osteocytic messengers
- The resulting synovitis and exposure of the subchondral bone results in pain and reduced movement in the joint
- The inflammatory process also produces a thickening of the joint capsule which reduces the range of movement seen in the joint
What class of analgesics are used in osteoarthritis?
How do they work?
Non-steroidal anti-inflammatory drugs
* They act on two receptors COX1 and COX2
* COX2 are those which mediate inflammation whereas COX1 are involved in regulating blood flow to the kidneys and gastric mucosa
* Those which preferentially block COX 2 are less likely to cause GI ulceration (there is no evidence that antacids protect the stomach from this action)
What is the mechanism of action of each of these NSAIDs? what are they licensed for?
Carprofen, Meloxicam, cimicocib, firocoxib, grapipant, ketoprofen
Carprofen (many commercial preparations) (selective COX2 inhibitor) licensed for long term use in the dog only
Meloxicam (many commercial preparations-tablet and liquid forms)-licensed for long term use in the dog and cat and some small animals
Cimicoxib (Cimalgex) (selective COX2) licensed for long term use in the dog. Not licensed in the cat
Firocoxib (Previcox) (selective COX2) licensed for long term use in the dog. Not licensed in the cat
Grapipant (Galliprant) (this is a piprant, an EP4 receptor antagonist blocking PGE2. It is not a COX inhibitor) licensed for long term use in the dog. Not licensed in the cat
Ketoprofen (Ketofen) (not COX2 selective) licenced for 30 day use in the dog but only 5 days in the cat
What opiates can be used in severe acute arthritis?
- Tramadol (an oral opiate)-the efficacy and appropriate dosage has not been determined
- Buprenorphine can be administered sublingually and systemic levels have been shown to be similar than when the compound is given by IM injection in the cat.
With long term osteoathritis the spincal cord can become more sensitised to the pain, what analgesia can you use to counteract this?
Gabapentin. May alter GABA metabolism in the spinal cord and result in a central analgesia in both the dog and cat
What drugs can be used after NSAIDs fail or as an adjunctive to NSAIDs for osteoathritis management?
Amantadine is a NDMA (nitrosodimethylamine) antagonist similar to ketamine which can also be used in the management of osteoarthritis. It is used primarily in the dog when non-steroidals fail to provide adequate analgesia and provides a central action
Paracetamol is a useful adjunct to the NSAI. It is used only in the dog as the cat shows a severe and often fatal toxic reaction
Librela (bedinvetmab) in the dog and Solensia (frunevetmab) in the cat are used for osteoathritis management.
How do they work?
what are the disadvantages and advantages?
Monoclonal antibodies directed against nerve growth factor
* Nerve growth factor plays a role in the inflammatory process and also increases the sensitivity of the nociceptive neurons
* The injection is given once monthly and is effective and easier for the client to manage
* Each injection is reasonably expensive but not necessarily so when comparing with long term NSAI medication
* Few side effects as the antibody is degraded like other proteins by natural processes
What steroids are used intra-articularly in dogs?
What are the warnings with using corticosteroids for osteoathritis management?
Intra-articular preparations include triamcinolone and methylprednisolone (depomedrome)
- These are used in the shoulder particularly but should not be given on multiple occasions as this predisposes to cartilage degeneration and soft tissue mineralisation
- Systemic side effects result from both systemic and articular use
disease modifying drugs osteoarthritis
What is the drug name of the Cartrophen?
What can they not be used along side?
How do they work?
- Pentosan polysulphate a polysulphonated polysaccharide
- A single injection given weekly over a four week period. It should not be combined with NSAIDs
- It has potent anti-inflammatory activity but is not an analgesic
- Stimulates mesenchymal stem cells to repair cartilage damage
- Reduces the inflammatory changes that damage the articular cartilage
- Improves blood flow to the affected joints
- Improves the quality and quantity of the synovial fluid
What disease modifying drugs can be used in osteoathritis?
- Platelet rich plasma - It contains many growth factors which are thought to stimulate mesenchymal stem cells and have anti inflammatory activity
- IRAP (Orthokine)
- Stem cells - can be combined with PRP
- hyaluronic acid - intra-articular or oral
- Polyacrylamide polygel (Arthramid) - adheres to the synovial membrane joint capsule, synovial membrane to thicken and become more cellular which offers a protective function to the joint, synovial fluid increases in volume
What nutraceuticals might be beneficial for osteoathritis?
where can they be found?
There is some evidence for the efficacy of omega 3 fatty acids
Evidence of the beneficial effects of other compounds is scant although green lipped mussel and elk velvet antler have shown some promise
Can be found in supplements or specific diets
What ‘other’ management options can help with osteoathritis?
- reduce weight
- Introduce standard and consistent exercise on level surfaces (involve the owner). This can be cheap and highly effective
- Environmental modifications such as ramps and non slip surfaces in the house and limit the use of stairs
- Larger baskets for dogs and cats to sleep in
- Photobiomodulation-laser therapy-cold infra-red light (K laser) (type IV)
- Extracorporeal shockwave treatment
- hydrotherapy (watertreadmill improves muscle mass)
If medical management of osteoarthritis fails then what are the other options?
salvage proceduces:
* Joint resurfacing:
* Arthrodesis
* Arthroplasty
* Joint replacements:- hip, stifle, elbow and hock- total or partial
* Euthanasia- although uncommon this can be the eventual outcome of this disease process particularly in the older dog when they are no longer able to rise or walk any distance
