Papers/Short answers Flashcards
Diagnostic yield of D-dimers and thromboelastography in diagnosis of canine CVA?
Low
Neither D-dimer concentration nor TEG was significantly associated with a CVA (P = .38 and .2, respectively). D-dimer testing was performed in a low-risk population and showed low sensitivity (30.8%; 95% confidence interval [CI], 10%-61%) and high specificity (86.4%; 95% CI, 64%-96%) for CVA diagnosis. Thromboelastography was performed in a high-risk population and showed moderate sensitivity (64.3%; 95% CI, 44%-81%) and specificity (66.7%; 95% CI, 24%-94%) for CVA diagnosis. Abnormal D-dimer concentration or TEG were not helpful in differentiating hemorrhagic from ischemic stroke (P = .43 and .41, respectively).
Most important clinical and MRI findings in dogs with idiopathic oculomotor neuropathy?
Outcome?
1) unilateral ophthalmoplegia/ophthalmoparesis (internal, external, or both) with the absence of other neurologic and ophthalmic signs - mostly combined 79%, or internal (mydriasis) 21%
2) MRI findings
restricted to the oculomotor nerve (enlargement + contrast enhancement)
3) good prognosis, most cases improving or not deteriorating without therapy
Which breeds are most commonly affected by idiopathic oculomotor neuropathy?
Boxers and border collies
Which CN is affected in this image?
9.5-year-old male entire Staffordshire
Bull Terrier
Mydriasis secondary to internal ophthalmoplegia, and upper eyelid ptosis and neuromuscular strabismus (dorsolateral) secondary to external
ophthalmoparesis of the OS
What is the middle cranial fossa (sinus cavernosus) syndrome?
a paired depression of the basiphenoid bone, located
between the rostral and caudal cranial fossa at the base
of the skull.
CN III, IV, V, VI travel there and exit the skull through the orbital fissure (oculomotor nerve, trochlear
nerve, abducens nerve, and ophthalmic branch of the
trigeminal nerve),
round foramen (maxillary branch of the
trigeminal nerve), or
oval foramen (mandibular branch of the trigeminal nerve)
The middle cranial fossa syndrome is a well-recognized syndrome in dogs characterized by variable impairment of these nerves (usually due to neoplastic mass lesion of the middle cranial fossa)
Which medication can cause hypo/anosmia
Metronidazole (careful in working dogs for explosive detection)
Genetic epilepsy - which breeds and variants?
1) Lagotto Romagnolo - benign familial juvenile epilepsy (LGI2)
2) Rhodesian Ridgeback - juvenile myoclonic epilepsy with photosensitivity (DIRAS1)
ADAM23 gene - Belgian shepherd, schipperke, Finnish spitz, and beagle, Australian shepherd, Kromfohrländer, Labrador retriever, whippet, –> proposing ADAM23 as a common risk gene for epilepsy with low penetranc
- susp: Dutch partridge dogs (CCDC85A)
Where data are sufficient, they usually support an autosomal recessive or polygenic recessive inheritance (De Lahunta)
Describe postictal MRI changes in dogs
T1W hypointense, T2W/FLAIR hyperintense with no or minimal contrast enhancement, and no to minimal local mass effect.
Locations: pyriform lobes and cyngulate gyri, hyppocampus, less commonly in the thalamus and frontal/parietal lobes.
Mostly bilateral and symmetric.
*These lesions are usually transient and not visible on repeat imaging (weeks to months later) once seizure control is achieved. On microscopic examination, these lesions consist of edema, vascular proliferation, neuronal loss, reactive astrogliosis, and occasionally neuronal necrosis. Similar findings are reported in humans and are presumed to be related to the excitotoxic effect of accumulated glutamic acid, which leads to cytotoxic edema.
Which horse breed has a presumptive genetic epilepsy?
Arabian foals . onset 3-9 MO, seizures may spontaneously cease after a few weeks
Adult horses may have IE related to the estrous cycle when estrogen levels are increased.
On the basis of negative autopsies in adult horses with late-onset epilepsy, this species may have an idiopathic epilepsy that is not apparent until at least 5 years of age.
DeLahunta
Toxins able to cause seizures (most important ones)
Lead: paint, linoleum, tar paper, wallboard, and roofing materials.
Metaldehyde - snail bait,
Hexachlorophene soap, ethylene glycol antifreeze, chlorinated hydrocarbon and organophosphate insecticides, fluoroacetate (1080), rodenticide (particularly bromethalin), fungicides with mercury, arsenicals in insecticides, and phenol and cresol germicides, and 5-fluorouracil.
De Lahunta
CBC changes with lead poisoning (in a dog with seizures)
Nucleated red blood cells, basophilic stippling, and a low packed cell volume (PCV) (may be present)
De Lahunta
How can the bromide serum levels be decreased more quickly then by simply discontinuing the drug?
NaCl IV infusion
De Lahunta
Which ASM has the potential to cause megaoesophagus?
KBr
- develops in the first few months of initiating therapy. It resolves rapidly with discontinuation of potassium bromide.
De Lahunta
Two phases of sleep
1 slow-wave
2 REM (or paradoxical)
During slow-wave sleep, normal resting muscle tone exists. In paradoxical sleep, complete atonia of all skeletal muscles occurs, except those necessary for respiration. This state causes a flaccid paralysis. Sporadically, the extraocular muscles breakthrough this lower motor neuron (LMN) inhibition and contract, causing eye movements, which is the basis for also naming paradoxical sleep rapid eye movement sleep. This portion of the sleep cycle is when dreaming occurs. Occasionally, other muscle groups break through this inhibition and contract. This breaking through is what is observed in small animals when, during their sleep, they exhibit facial muscle twitches or sporadic movements of their digits.
During slow-wave sleep, a decrease occurs in the heart and respiratory rates. In paradoxical sleep, respirations are shallow, more rapid, and irregular. Normally in small animals, slow-wave sleep occurs in 10- to 15-minute intervals, with approximately 5 minutes of paradoxical sleep.
Four components of Narcolepsy in humans
1) excessive daytime sleepines
2) cataplexy - collapse due to complete atonia of skeletal muscles - the most common sign we observe in animals
3) hypnagogic hallucinations
4) sleep paralysis
-these 2 can only be appreciated in humans
Which breeds have an inherited basis for narcolepsy and which gene is involved?
CANARC gene - chromosome 12
- autosomal recessive
doberman pinschers, Labrador retrievers, and dachshunds
(the gene codes for a hypocretine receptor found on neurons of the locus coeruleus and dorsal raphe nucleus)
Two forms of narcolepsy
1) genetic (CANARC gene) - defect in the hypocretin receptors in dorsal raphe nucleus and locus coeruleus neurons
2) acquired - low hypocretin levels in CSF (immune mediated destruction of the neurons of ventrolateral hypothalamic nucleus?)
Which drugs facilitate and which inhibit paradoxical sleep?
1) Physostigmine and arecoline facilitate
2) atropine, scopolamine, norepinephrine, serotonin inhibit it.
De Lahunta
Breeds of horses with an inherited form of narcolepsy
Shetland ponies, the American miniature horse, and probably the Suffolk draft horse
De Lahunta
DDs for cataplexy?
Syncope - rapid onset and recovery, same as cataplexy
Seizure - uncontrolled muscle movements (and cataplexy is atonic)
Neuromuscular disorders - not so abrupt and recovery not so quick
Which drug can be used to provoke a cataplectic episode?
physostigmine at 0.05 to 0.1 mg/kg of body weight should not induce cataplexy in a normal dog but may provoke an episode in the patient at risk for such an episode
Which drugs can be used to stop a cataplectic episode?
1) imipramine (Tofranil) IV at 0.5– 1.0 mg/kg of body weight, - antidepressant that inhibits the reuptake of norepinephrine and has anticholinergic actions.
2) IV atropine sulfate at 0.02–0.04 mg/kg of body weight may also interrupt the episodes.
Which gene variant is associated with congenital myotonia?
DNA mutation of the gene responsible for chloride channel 1 in the muscle membrane
CLCN1
This voltage-gated chloride channel 1 plays a role in the repolarization of the muscle cell membrane after contraction. When the function of this channel is deficient, muscle cell relaxation is delayed. No light microscopic lesions exist in the affected muscles of animals with inherited nondystrophic myotonia.
Breeds of animals with congential myotonia
Documented in:
- rats
- goats (pygmy)
- horses
- cats
- dogs
- buffaloes
- pigs
Dog breeds with CLCN1 variant:
Miniature Schnauzer
Jack Russell Terrier (common)
Australian Cattle dog
Labrador Retriever
American Bulldog
In addition to these breeds, has been described clinically in Cocker Spaniels and
Chow Chows (common)
Most likely diagnosis?
1YO Chow chow with muscle atrophy and stiff gait
Myotonia congenita
Most likely diagnosis?
8 MO standardbreed with stiff gait
Myotonia congenita
Most likely Dx in this cow?
Tetanus
Note the retracted ears, taut lips, extended neck, and elevated tail.
Causes of tetany
1) hypocalcaemia
2) strychnine intox
3) inherited congenital tetany in polled Hereford calves (aka inherited congenital bovine myoclonus) (Glra1 gene variant)
4) familial reflex myoclonus of Labrador retriever puppies
5) lavender Arabian foal syndrome (lethal) (MYO5A gene)
Dysfunction of which nerves is seen in bovine spastic paresis (Elso heel)?
hyperactivity of the γ-efferent neurons that innervate the intrafusal muscle fibers in the neuromuscular spindles of the gastrocnemius muscle
Dog breed with susp. inheretad basis for orthostatic tremor (postural repetitive myoclonus)
young adult Great Dane
Clinical signs in horses with tetanus?
- Stiffness (most commonly) - horses are hesitant to lower their neck
- stilted gait
-retraction of lips, flaring of nostrils (risus sadonicus) - trismus
- prolapse of nicticating membrane
- urine retention
- fecal and gas retention
DDs: rabies, strychnine intoxication,
exertional rhabdomyolysis, and myositis.
