Musculoskeletal disease in small animals and exotic species

• What are the clinical signs of musculoskeletal disease in small mammals?

  Anorexia, lethargy, hiding.

  Wounds +/- fly strike.

  Gut stasis (hind gut fermenter)

  Not eating caecotrophs/ cleaning rear end.

  Hunched stance

  Urine staining

  Bruxism/ teeth grinding.

  Aggression or being bullied.

  Weakness or limping on one or more legs.
• What are the clinical signs of musculoskeletal disease in reptiles?

  Can be very subtle even with severe fractures.

  Abnormal stance and gait.

  Often may just seem more lethargic.

  Deformity of spine and limbs +/- generalised limb swelling.

  Wounds

  Swollen joints

  Weakness or limping on one or more legs.
• What are the clinical signs of musculoskeletal disease in birds?

  Clinical signs can be very subtle, even severe fractures.

  Abnormal or wide stance +/- reduced grip.

  May use beak or ipsilateral wing for support.

  Affected leg may feel warmer.

  Bumblefoot on contralateral limb.

  Weakness or limping on one or more legs.
• What are the disease categories for lameness in exotics?

  Musculoskeletal diseases:

  • Similar to other species e.g. degenerative joint disease, infections and neoplasia.

  Metabolic and nutritional causes of disease:

  • More common compared to dogs and cats.

  Trauma:

  • From cage mates, other pets and owners.
• What is the diagnostic plans for investigating lameness in exotics?

  Imaging:

  • First line - radiographs, ultrasound.
  • Referral - arthroscopy, CT and MRI.

  Blood works:

  • Biochemistry for underlying causes (including ion calcium.
  • Haematology to look for dehydration, infections/ blood loss

  Joint fluid analysis - infection/gout etc.

  Cytology:

  • Joint aspirates, wounds.

  Culture and sensitivity - joint infections, wounds.

  Biopsy histopathology - bone or soft tissue.
• What are common primary MSK problems in rabbits?

  Pododermatitis/bumblefoot

  Degenerative joint disease e.g. stifle and spine.

  Spinal deformities and injuries

  Fractures e.g. spine, limbs

  Osteomyelitis

  Luxation e.g. hip, elbow and tarsus.

  Primary neoplasia e.g. osteosarcoma.

  Splay leg e.g. genetic or trauma.
• What are common secondary MSK problems in rabbits?

  Abscesses: bite wounds -> systemic spread to joints.

  Metastatic neoplasia e.g. uterine adenocarcinoma.

  Nutritional Secondary Hyperparathyroidism (NSHP): Muesli mix, lack of UV-B

  Renal failure -> hypercalcaemia -> soft tissue calcification and bone hypercalcification.

  Encephalitozoon cuniculi (parasitic) -> hind limbs paresis.
• Rabbit fractures caused by trauma

  Fractures often occur when rabbit is dropped or jumps from height.

  Rabbits tend to make sudden, surprise escape attempts.

  Jaw fracture commonly occur bit are easily overlooked.

  
• Fractures secondary to disease in rabbits

  Osteosarcoma of tarsus.

  Pathological distal femoral fracture caused by uterine adenocarcinoma metastasis. This stifle is also affected by osteoarthritis.

  
• What spinal deformities do rabbits get?

  Spondylosis, kyphosis, lordosis and scoliosis all occur quite commonly.
• Why do rabbits get spinal deformities?

  Due to small cages and a lack of exercise are risk factors.
• What are the consequences of spinal deformities in rabbits?

  May interfere with locomotion, caecotrophy, urination and grooming; often incidental finding.

  May result in faecal soiling, urine scald, unkempt coat, Cheyletiella, facial dermatitis and gut stasis due to pain.
• What are common MSK problems in rodents?

  Pododermatitis is common in guinea pigs, chinchillas and rats.

  Overgrown claws and keratin horns in guinea pigs -> lameness.

  Metastatic calcification -> degenerative joint disease in guinea pigs.

  Fractures are relatively common in chinchillas and hamsters e.g. dropped or entrapped in cage bars or exercise wheel.
• What are common MSK problems in ferrets?

  Hindlimb paresis is a common but often due to non-musculoskeletal disease e.g. hypoglycaemia or cardiomyopathy.

  Trauma e.g. long bone fractures.

  Luxation e.g. elbow

  Abscessation of the spine.
• What are common primary MSK problems in birds?

  Trauma e.g. long bone fractures (often compound/open). Coracoid fractures and spinal injury (head on collision).

  Pododermatitis/bumblefoot.

  Nutritional secondary hyperparathyroidism.

  Osteomyelitis and septic arthritis.

  Osteoarthritis, often in older birds +/- injury.

  Tenosynovitis and tendon injury e.g. infection, bites, equipment rubbing.

  Growth deformities e.g. osteodystrophy, luxated gastrocnemius tendon.
• What are common secondary MSK problems in birds?

  Kidney disease and gout

  Viral e.g. marek’s disease in chickens.

  Egg binding

  Lead poisoning.
• Pododermatitis in birds and small animals

  Pressure-sore on the plantar surface of foot often due to poor blood circulation.

  Allows entry of infection which may progress to osteomyelitis.

  Poor perching surfaces (birds) or substrates/flooring (small mammals) +/- trauma, poor hygiene, obesity, hypo vitamin A.

  Important to examine and radiograph both limbs.
• What are common primary MSK problems in reptiles?

  Luxation

  Tendon/ligament injury or infection.

  Spinal injury e.g. trauma, NSHP, burns.

  Septic arthritis/osteomyelitis (remember reptiles have solid pus).
• What are common primary MSK problems in reptiles?

  Fractures - commonly due to NSHP/RSHP (MD)

  Gout

  Pre and post-ovulatory oostasis.

  Urolithiasis (if they have bladders e.g. tortoises)
• Gout in birds and reptiles

  Birds excrete nitrogenous wast as urates.

  Renal dysfunction decreases the clearance of uric acid from within the blood -> hyperuricemia. Which then leads to precipitation of insoluble products within the body (urate deposition or urolithiasis).

  Urate deposits are white and semisolid.
• What are the tow types of gout in birds and reptiles?

  Visceral urate deposition -> urate deposits in soft tissues.

  Articualr urate deposition -> urate deposits in synovial membranes -> chronic granulomatous reaction -> lameness.
• What is the treatment option for metabolic bone disease?

  Heavy external coaptation and/or surgical fixation are contraindicated with NSHP.

  Cage rest, analgesia, supplement calcium and vitamin D, provide UV-B and start to correct the diet.

  Diet changes slow and graduate in birds.
• What are the general principles for treating MSK diseases in exotics?

  Most treatments are the same as cats and dogs.

  Clean, dry, comfortable bedding e.g. cover perches in vet wrap.

  Clean wounds and rabbits clean perineum (fly strike)

  Surgical fixation of fractures is often preferred but not if MBD.

  Osteomyelitis is a significant risk with exotics and small mammals with open wounds or with poor surgical technique.

  Antibiotics may be needed e.g. open wounds, joint infections.
• What are the fracture repair methods?

  Cage rest only (pelvis or clavicle).

  External stabilisation (if a bone is too small for internal stabilisation).

  Internal fixation (IM pins work well in avian bones).

  ’Hybrid’ fixation (IM pins with external skeletal fixators).
• What are the considerations for fractures in birds?

  The birds lifestyle should be considered when assessing prognosis and treatment (cage bird vs wildlife). The main aim is to restore limb function as soon as possible.

  Hyvbrid fixator is able to oppos axial, shear, blinding, torsional and compressive forces acting on fractures. In the case of falconry birds or bird of prey wildlife casualties this is necessary.

  Higher bone mineral content, so high risk of open, comminuted fractures.
• When should you consider euthanasia for birds with fractures?

  Fractures which are compound and/or close to joints carry a poor prognosis for return to normal function/release.

  Ocular damage occurs in 80% if impact injuries.
• What is the treatment for grade 1-3 pododermatitis in exotics?

  Non-surgical

  Husbandry changes.

  Topical or systemic antibiotics if needed.

  Pain relief, such as an NSAID
• What is the treatment for grade 4-5 pododermatitis in exotics?

  Surgery needed to debride, remove the core and flush.

  Radiographs to assess bone involvement.

  Send swab/material away for culture and sensitivity.

  Dressings in birds (ball bandage/shoe bandage)

  Cannot use collars in hind gut fermenters.

  Pain relief, such as opioids.
• What are the causes of pododermatitis in exotics?

  Incorrect flooring/ hard perches of the same thickness.

  Obesity.

  lack of exercise.

  Poor hygeine

  Nutritional deficiencies.
• What are the causes of trauma in exotic species?

  Incorrect or dangerous environment e.g. wire cage.

  Incorrect or dangerous handling e.g. rabbits.

  Tethering and using equipment incorrectly.

  Poor protection from other animals e.g. wildlife or other pets.

  Unbalanced flight e.g. one sided wing clipping.

  Escaping an enclosure e.g. falling out if viv or flying out of cage.
• What are the causes of metabolic disease?

  Incorrect diet +/- supplements.

  Low environmental temperatures.

  Lack of UV-B light.
• What are the potential limitations of Diagnosisng and managing bone disease in exotics?

  Tendency to hide disease well.

  Normal gait varies across species.

  Patient size and demeanour can make a full clinical examination difficult or impossible.

  Sedation or GA often required.

  Subtle lesions and even dome fractures can be difficult to diagnose, especially in smaller patients.

  Equipment hard to find due to sizes and requirements.