Neurological disease in small mammals and exotic species

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

  Head tilt

  Weakness

  Paresis

  Swaying/ataxia

  Tremor

  Seizures

  Circling

  Exophthalmos

  Ocular discarhge

  Mydriasis

  Nystagmus

  Urinary incontinence

  Loss of anal tone

  Faecal impaction.
• What are the clinical signs of neurological disease in reptiles?

  Loss of righting reflex - if put in side should right itself, if don’t then is linked to neurological problem.

  Loss of withdrawal refelxes.

  Loss of cloacal tone

  Limb paresis (hind most common)

  Reduced grip (snakes)

  Generalised or localised weakness.

  Tremors and convulsions.

  Blindness

  Circling

  Head tilt.
• What are the clinical signs of neurological disease in birds?

  Loss of withdrawal reflexes (very reliable).

  Loss of cloacal tone.

  Limb paresis

  Reduced foot grip

  Generalised weakness.

  Tremors and convulsions.

  Circling

  Head tilt
• What are the differential diagnoses for neurological disease for small mammals? (DAMN)

  Degenerative - e.g. spondylosis, osteoarthritis, intervertebral disc protrusion.

  Anomalous - e.g. splay leg

  Metabolic - e.g. heat stroke, azotaemia, electrolyte imbalance, pregnancy toxaemia, hypocalcaemia, hypoxia.

  Neoplastic - e.g. spinal or brain neoplasia, rat pituitary gland adenoma.

  Nutritional - e.g. hypovitaminosis A.
• What are the differential diagnoses for neurological disease for small animals? (ITV)

  Inflammatory, immune mediated and infections - e.g. herpes virus (encephalitis), encephalitozoon cuniculi, bacterial otitis media/interna, spinal abscess, toxoplasmosis.

  Idiopathic - e.g. dysautonomia, idiopathic vestibular disease, idiopathic epilepsy.

  Toxic - e.g. antibiotic, lead, fipronil, pyrethrin/permethrin.

  Trau stic - e.g. vertebral fracture/luxation.

  Vascular - e.g. cerebrovascular accident.
• Vestibular disease in small mammals

  Central vestibular disease:

  • Nystagmus (vertical or horizontal)
  • No Horner’s or facial paralysis
  • Can show other CNS signs.

  Peripheral vestibular disease:

  • Nystagmus (horizontal, fast away from lesion).
  • Can show Horner’s syndrome
  • Can show Horner’s syndrome or facial nerve paralysis.
  • Does not show any other CNS signs.
• Otitis media in rabbits

  Lop rabbits are predisposed.

  Inner ear infection. Infection penetrates through the tympanic membrane, progression from otitis external.

  Causes ataxia, circling, head tilt.

  Pray animals so hide the pain of otitis externa.

  Ear anatomy and lack of ventilation in lop eared breeds predispose to this, often an incidental finding.
• Encephalitozoon Cuniculi

  Fungi spread in rabbit urine mostly.

  Over 50% healthy rabbits are carriers.

  Clinical signs are mostly due to inflammation:

  CNS damage:

  • Hind limb paralysis/weakness (can be diagnosed as arthritis)
  • Torticollis
  • Urinary incontinence.
  • Tremors.

  Kidney damage:

  • PUPD
  • Weight loss
  • Anorexia
  • Cataracts and uveitis.
• How does encephalitozoon cuniculi spread?

  Pathogen ingested in contaminated food and water (usually spread in rabbit urine).

  Pathogen moves via the blood stream into the kidneys.

  Pathogen intermittently passed in urine.

  Pathogen then moves into the spine -> hind limb paresis.

  Pathogen then moves up the spine to the brain -> head tilt.
• Muscular weakness - floppy bunny syndrome


  Generalised flaccid paralysis but the rabbit is often very alert with a good appetite.

  Exact cause unknown.

  Majority of rabbits recover within 3-4 days with supportive care.
• What are the clinical signs of rabbit fipronil toxicity?

  Seizures

  Tremors

  Hyperactivity

  Diarrhoea

  Hypersalivation

  Hypothermia

  Death
• Why is Fipronil toxic for rabbits?

  Fipronil blocks GABA receptors in the CNS -> stops chloride ion uptake -> excessive CNS stimulation -> death.
• What are the viruses that cause neurological signs in reptiles?

  Inclusion body disease (IBD) in snakes.

  Ophidian Paramyxovirus (snakes)

  Adenovirus (any reptile, mostly bearded dragons).
• What are the neurological signs for IBD?

  Head tremor

  Uneven pupils

  Muscle spasms (head can arch backward AKA stargazing)

  Lethargy

  Reduced mental activity

  Poor righting reflex.

  Reduced muscle tone

  Constipation.
• Reptile drug toxicities - Ivermectin


  Can cause depression, paralysis, and death in Chelonia.

  Sensitives reported in other reptile species.

  Gastric Lavage, charcoal - doesn’t always work.
• Reptile drug toxicities - metronidazole

  High doses (>100mg/kg) can cause vestibular disease (head tilt, circling, and disequilibrium).

  With supportive treatment can recover.

  Particular species are susceptible at lower doses e.g. indigo snakes.
• What are the clinical signs for Marek’s disease?

  Lameness/leg paralysis - hind leg paralysis most common sign.

  Wing paralysis

  Weightloss/wasting

  Eye changes - loss common, brown discolouration to the pigment of the eye.

  • Tumours
  • Skin/feathers, liver, spleen, kidney, lung, gonads, heart, muscle.
• What are the clinical signs of hyperlipidaemia?

  Obesity/overweight

  Tremors/seizures

  Weakness

  Signs associated with liver damage a.g. diarrhoea/green faeces.
• What are the clinical signs of heavy metal toxicity?

  Clinical signs affect the GIT, renal, urinary and CNS.

  • Regurgitation, lethargy, weakness, anorexia, weight loss, anaemia, polydipisia, diarrhoea, haemoglobinuria.
  • CNS clinical signs: depression, seizures, head tilt, blindness.
• What is Psittacosis?

  Caused by bacteria Chlamydia psittaci (Zoonotic)

  Very contagious, via faeces, urine and respiratory secretions.

  Mild to severe, depending on bird.
• What are the clinical signs of Psittacosis?

  Respiratory (dyspnoea, oculonasal discharge)

  GIT (bright green faeces, regurgitation)

  CNS ( tremors, twisting of the head and body)

  Sudden death (especially lovebirds).
• What are the diagnostic screening options for small mammals and exotics?

  Clinical exam e.g. head trauma.

  History e.g. toxicities.

  Imaging:

  • Radiography
  • CT
  • MRI - requires referral.

  Blood testing (haematology and biochemistry)

  • Looking for metabolic causes, organ damage, infection, blood loss (trauma) and signs of toxicity e.g. anaemia.
• What are the options for pathogen testing in small mammals and exotics?

  Antibody testing - body’s testing to the pathogen.

  Antigen testing - the pathogen itself.

  PCR, ELISA

  Bacteriology (culture and sensitivity).

  Histology
• What are the diagnostic options for Otitis Media?

  Otoscopic examination

  Ear base palpation

  Imaging (radiographs or CT).
• How do you diagnose heavy metal toxicity?

  History plus clinical signs.

  Blood work can make you suspect toxicity.

  Radiographs to identify metal in the GIT.
• How do you diagnose hepatic lipidosis?

  Bloods:

  • Grossly lipaemic if severe.
  • Cholesterol, liver values raised
• How do you diagnose E.Cuniculi?

  Blood test antibody serology (ELISA)

  • If exposed in past will have antibodies.
  • IgM (acute) vs IgG (chronic)
  • Very high levels can be diagnostic.
  • Moderate levels re-test in 4 weeks to look for an increase or decrease in levels.
  • In increased in 4 weeks = diagnostic.

  Urine antigen test (PCR):

  • Unreliable as intermittently shed.
  • Used for screening groups e.g. petting zoo.
• How do you diagnose Mareks disease?

  Presumptive diagnosis on clinical signs and gross post mortem examination.

  Histopathology (brain, eyes, masses/tumours, sciatic nerve).

  PCR available
• How do you treat Otitis External and Media?

  Antibiotic ear drops (eye drops to avoid steroid)

  Analgesia (NSAID)

  Culture and sensitivity (Pastuerella very common)

  Ear flush under sedation if needed (lots of puss/debris)

  Aural base ’abscesses’ can be gently massaged to remove the build up of debris, may require flushing or surgery if not successful.
• What is the treatment for Otitis External and Media?

  Antibiotic ear drops (eye drops to avoid steroid).

  Analgesia (NSAID)

  Culture and sensitivity (Pastuerella very common).

  Ear flush under sedation if needed (lots of puss/debris)

  Aural base ‘abscesses’ can be gently massaged to remove the build up of debris, may require flushing or surgery of not successful.
• What is the treatment for recurrent or non-responsive ear infections?

  Partial or total ear canal ablation with lateral bulla osteotomy.

  Risks include facial nerve paralysis and vestibular disease, it is painful and invasive so they can get gut stasis.
• What is the treatment for E.Cuniculi?

  Treatment eases the symptoms by reducing inflammation, but does not reverse damage already done.

  • Biosecurity - isolate, disinfect environment
  • Kill parasites
  • Vertigo - Prochlorperazine (drugs are hard to get hold off in the UK), darkness, support with rolled up towels.
  • Remove inflammation - NSAID (can cause kidney damage) Short acting steroids (react badly to steroids, can make them quite ill).
  • Gut support.
• What is the treatment for Hepatic lipidosis?

  Diet changes slowly over 6 months

  • They will stop eating with sudden changes in diet.
  • Starvation causes potentially fatal fat release from the liver into the blood.

  Liver supplements e.g. milk thistle, Hepatosyl, lactulose
• How do you treat heavy metal toxicity?

  Supportive treatment e.g. fluids, warmth, crop feeds. Might be the only option for wildlife.

  Calcium EDTA is a commonly used chelating drug.

  • BID until asymptomatic then twice weekly till blood lead levels are in the normal range.

  Remove metal particles from the GI tract, otherwise will continue to be toxic.

  • Most small particles will pass through in 4-5 days.
  • Larger pieces may have to be removed endoscopically or as a last resort, surgically.