Incorrect/Trouble MCQ - Practice Questions Flashcards
What is the method of choice for diagnosing rabies?
A. Visualization of Negri bodies
B. Immunohistochemistry
C. RT-PCR
D. Gross pathologic lesions
E. Direct fluorescent antibody test
Explanation
The correct answer is direct fluorescent antibody test. There are no gross pathologic lesions associated with rabies. A diagnostic microscopic lesion is the visualization of Negri bodies. Most commonly they occur in the hippocampus in carnivores and Purkinje cells in herbivores. However, these are only seen 50% of the time. Immunohistochemistry allows strain differentiation and the ability to differentiate vaccine vs. wild-type. RT-PCR has been used on autolyzed brain tissue that is difficult to evaluate with fluorescent antibodies, but this is not the test of choice at this time. Direct FA is the current preferred method of diagnosis; it is both rapid and sensitive. Usually impressions of the medulla, cerebellum, and hippocampus are performed.
Which of the following is a possible sequela to a CN VII (facial nerve) deficit?
Exposure keratitis
Strabismus of the eyes
Loss of motor function in the muscles of mastication
Nystagmus
The correct answer is exposure keratitis. CN VIl is responsible for lacrimation. Deficits in lacrimation would cause exposure keratitis. Loss of motor function in the muscles of mastication would occur in CN V (mandibular branch) deficits. Strabismus of the eyes would be caused by deficits in CN III (oculomotor nerve), CN IV (trochlear nerve) or CN VI (abducent nerve). Nystagmus occurs with CNS disease or CN VIII deficits.
A 4-year old male castrated Dachshund presents for further evaluation after developing acute hind end paresis. A neurologic exam warranted advanced imaging and a myelogram was performed. Based on the image below, where is the lesion?
Right side T12-T13
Left side T12-T13
Left side L2-L3
Right side L2-L3
Left side T13-L1
The correct answer is left side T13-L1. Looking at the myelogram one can appreciate the contrast column on the right side acutely stop at approximately the level of T13-L1. Furthermore, the dye column appears to be deviated toward midline both cranial and caudal to the region of the disruption. This is characteristic of extradural compression. The most common cause of this in a Dachshund is a disc herniation.
Red circle: There was attenuation of the contrast columns from the cranial aspect of T13 to `the caudal aspect of L1. There was marked rightward deviation of the left contrast column on the VD view.
A 7 year old Poodle presents for a left sided head tilt, a ventral strabismus on the left, and right horizontal nystagmus. The dog is obtunded, has conscious proprioception deficits in both right limbs, and a right sided facial paralysis. Where is the lesion?
Peripheral nerve on the right
Central nervous system on the right
Peripheral nerve on the left
Central nervous system on the left
The correct answer is central nervous system on the right. This dog has paradoxical vestibular disease. This disease is usually caused by a destructive lesion in the CNS in which there is loss of inhibition of the vestibular output on the side of the lesion. There is therefore a relative increase in vestibular output on the side of the lesion, causing vestibular signs on the side opposite the lesion (yes, this can be confusing). In this case, the right sided lesion has vestibular signs that would normally localize the lesion to the left side. When the lesion causes vestibular signs and proprioceptive deficits, the lesion is ipsilateral to the side with the proprioceptive deficits.
What is the correct post-exposure prophylaxis protocol after being exposed to rabies for an unvaccinated human?
Three injections of human rabies immune globulin followed by 2 injections of approved rabies vaccine
Two injections of approved rabies vaccine
Five injections of approved rabies vaccine
Injection of human rabies immune globulin followed by 4 injections of approved rabies vaccine
One injection of human rabies immune globulin followed by 2 injections of approved rabies vaccine
Explanation
The correct answer is injection of human rabies immune globulin followed by 4-5 injections of approved rabies vaccine.
The recommended protocol per the 2020 CDC guidelines is as follows: “Postexposure prophylaxis (PEP) consists of a dose of human rabies immune globulin (HRIG) and rabies vaccine given on the day of the rabies exposure, and then a dose of vaccine given again on days 3, 7, and 14.” HTTP://www.cdc.gov/rabies/
If you are not vaccinated, then you will need an injection of human rabies immune globulin immediately after exposure followed by 4-5 injections of an approved rabies vaccine IM over 2-4 weeks. If you have been vaccinated, all that is needed are two injections of an approved rabies vaccine 3 days apart. PEP is not required for accidental injection of animal rabies vaccine into a human.
The key here is to recognize that the question is asking about peripheral vestibular disease; otherwise, metronidazole would be a good choice as a cause of central vestibular disease. Chlorheadine is a topical drug implicated in ototoxicity and peripheral vestibular disease.
Another excellent choice would be aminoglycosides including neomycin, kanamycin, tobramycin, amikacin and gentamicin.
A 3 year old mixed breed dog presents after falling from a height of 10 feet and landing on the caudal half of his body. Since the fall, the dog has been dribbling urine and dropping feces as it walks. Neurologic exam reveals no abnormalities in the thoracic limbs, and hypo-reflexive patellar, gastrocnemius, and withdrawal reflexes in the pelvic limbs. Where is the lesion in the spinal cord?
C6-72
T3-L3
L4-53
C1-C5
The correct answer is L4-S3. The spinal cord is divided into the 4 regions listed above in the dog. Lesions at C1-C5 would manifest as UMN signs in the thoracic and pelvic limbs. Lesions at C6-2 would manifest as LMN for the thoracic limbs and UMN for the pelvic limbs.
Lesions at T3-L3 would not affect thoracic limbs and would cause UMN signs for the pelvic limbs. Lesions at L4-S3 would manifest as normal thoracic limbs and LMN signs in the pelvic limbs, anus, and bladder.
A 10 year old female spayed Labrador Retriever has presented for difficulty getting up in the hind and apparent back pain for the last 3-4 weeks.
Upon questioning the owner, you are told that her appetite is diminished but she is still eating. An orthopedic exam finds no pain or discomfort elicited on manipulation of the hips or stifles. A neurologic exam identifies substantial pain in the lumbosacral region; however, conscious proprioception is intact, and patellar reflexes are normal.
Radiographs of the lumbosacral region identify a lytic lesion at the L7-S1 endplates as well as surrounding bony proliferation. Which of the following diagnostic tests is likely to provide the most helpful additional information given your findings?
Chest radiographs
Abdominal ultrasound
Blood draw for creatine kinase levels
Stifle arthrocentesis
Urine culture
Explanation
The diagnosis you should have in mind is discospondylitis. Be sure not to confuse this with spondylosis, which is typically not clinically significant and can be expected in most older dogs. The radiographic description is relatively specific for this condition. Neoplasia in the spine should be lower on your differential list because it typically does not cross joints. Disc herniation cannot be ruled out, and advanced imaging would be necessary to know for certain, but given the exam and radiographic findings, discospondylitis should be your top differential.
Discospondylitis is usually bacterial in origin, with Staphylococcus being the most common organism involved. Other organisms identified include Brucella canis, E. coli, Pasteurella, Aspergillus, and Streptococcus.
In an attempt to identify the causative agent, urine and blood cultures should be considered. The other answer choices are not as high yield in identifying the specific bacterial cause or underlying etiology.
Intramuscular injections into the caudal aspect of the thigh muscles are most often associated with damage to which major nerve in the dog?
Tibial
Lateral cutaneous sural
Sciatic
Peroneal
The correct answer is sciatic. The sciatic is the most commonly damaged nerve from intramuscular injections given into the caudal musculature of the thigh. The sciatic, also known as the ischiatic nerve, is the largest nerve in the body of the dog. It arises from L6, L7, S1, and sometimes S2 nerve roots. It begins as the lumbosacral trunk exits the pelvis and travels down the caudal thigh. It then splits into the tibial nerve and common peroneal nerve further distal down the thigh.
A couple comes in frantic to your hospital with their two Labrador retrievers. Both dogs are unable to walk and need to be carried into the hospital. The owners had been camping with the dogs over the weekend and report that one of the dogs started to show signs of weakness in the hind end near the end of the trip. They assumed he was tired from running around as their other dog seemed more quiet on the way home as well. This morning when they woke up neither dog could stand and one of the dogs had trouble eating breakfast. Both dogs are up to date on vaccinations and preventatives.
The dogs are non-painful, tetraplegic, hypo-reflexive in all four limbs, superficial and deep pain intact, and their tails continue to wag. One of the dogs has decreased tongue tone. You do not find any external lesions. Initial complete blood count, chemistry panel and urinalysis are normal.
Of the following options, what is the most likely diagnosis for both dogs?
Myasthenia gravis
Botulism
Tick bite paralysis
Intervertebral disc disease
Coonhound paralysis
Explanation
When two patients are affected with the same symptoms your first thoughts should be something contagious, a toxin, or an environmental factor. All of the options are reasonable explanations for worsening paralysis; however, the history of camping and two patients being affected make something infectious high on your list of differentials. Intervertebral disc disease would be highly unusual to affect two large-breed dogs at the same time, and pain is often initially noticed on spinal palpation. Coonhound paralysis or idiopathic polyradiculoneuritis is often preceded by raccoon bite, systemic illness or vaccination, and no external wounds were seen on either patient. Tick bite paralysis resolves when the tick is removed. Myasthenia gravis can show similar signs (especially the difficulty with eating and swallowing), but it tends to show some improvement after rest and would be unlikely to spontaneously occur in two patients at the same time. Botulism is contracted from eating contaminated food containing the Clostridium botulinum type C neurotoxin. It can be found in carrion and spoiled food. Given that the dogs were out camping, they likely ate contaminated food when the owners weren’t looking and therefore became ill at the same time. The difference in severity between patients is likely related to the quantity of toxin ingested.
A 3 year old male neutered Doberman presents for weakness and difficulty walking. Your physical exam shows the dog is ataxic in all limbs, has conscious proprioception deficits in all limbs, and has a stiff, stilted gait in all limbs. All spinal reflexes are hyper-reflexive, and all limbs have increased muscle tone. Where is the anatomic localization of the lesion?
C6-2 of the spinal cord
C1-C5 of the spinal cord
T3-L3 of the spinal cord
L4 and caudal of the spinal cord
The correct answer is C1-C5 of the spinal cord. All 4 limbs are showing signs of an upper motor neuron lesion, which would be consistent with a C1-C5 myelopathy or multifocal spinal lesions. A C6-2 lesion would manifest as lower motor neuron signs in the thoracic limbs and upper motor neuron signs in the pelvic limbs. A T3-L3 lesion would manifest as upper motor neuron signs in the pelvic limbs with normal thoracic limbs. A L4 and caudal lesion would manifest as lower motor neuron signs in the pelvic limbs with normal thoracic limbs.
Remember that multifocal lesions in different areas of the spinal cord can make neuroanatomic localization trickier.
This 4-year old male castrated Chinese Crested presented with an acute onset of being down in the hind end. On neurological examination, the patient’s cranial nerves are intact, there is bilateral hind limb conscious proprioceptive deficits, no motor function in either hind limb, superficial pain is absent in the hind limbs. There are normo-reflexive gastrocnemius reflexes bilaterally, hyper-reflexive patellar reflexes bilaterally, and no obvious pain on palpation of the spine. The patient was hesitating to move the neck to the left and right on manipulation, but when offered a treat to the side the patient did not seem to have trouble moving the head from side to side. The most likely diagnosis is intervertebral disc herniation. Based on the neurological exam where is the site of your laminectomy most likely to be?
C2-С3
C7-T1
L4-L5
T13-11
The neurological exam findings, signalment, and history are all consistent with intervertebral disc disease. All small breed dogs are predisposed to disc herniation as compared to larger breeds. The most over-represented breed is the Dachshund.
The findings in the neurological exam that help determine the location are the following:
1) Conscious proprioceptive deficits only in the hind
2) Hyper-reflexive patellar reflex
3 Loss of motor in the hind
4) Lack of superficial pain in the hind
These findings should help you realize that the lesion is between T3-L3 or L3-S1. However, hyper-reflexia in the hind should stand out.
Hyper-reflexia in the hind limbs is an upper motor neuron sign and is supportive of a T3-L3 lesion. Therefore, L4-L5 is not the best answer.
Approximately 80% of T3-L3 herniations are located in the T13-L1 region.
There is no indication of forelimb involvement or neck pain which makes neck involvement less likely.
An 8 year old female spayed Labrador presents to you for progressive muscle loss on the skull. You examine the dog and see the changes visible in the photograph. The changes appear to be confined to the right side only. Which of the following conditions is most likely?
Right trigeminal neuropathy
Idiopathic polyradiculoneuritis
Myotonia
Right facial neuropathy
Masticatory muscle myositis
The correct answer is right trigeminal neuropathy. Hopefully, you were able to identify the presence of significant muscle atrophy of the right masseter and temporalis musculature. The nerve innervating these muscles is the trigeminal nerve. Recall that the trigeminal nerve (cranial nerve V) has primarily a sensory function, with the exception of innervating the muscles of mastication. The facial nerve (CN VII) innervates the muscles of facial expression and is the main motor nerve innervating the face but is not responsible for the muscles that are atrophied in this case. Masticatory muscle myositis is an autoimmune condition that chronically leads to atrophy of the same muscle group, but what differentiates this case is that the signs are unilateral. Idiopathic polyradiculoneuritis is the medical term for a condition sometimes referred to as Coonhound paralysis, which is a condition that diffusely affects all motor nerves.
A 9-year old male Queensland Heeler presents with a four day history of progressive tetraparesis. Physical exam showed him to be weakly ambulatory with support. As part of your initial workup, you take chest X-rays which are shown below. Which of the following next steps is the most appropriate test to confirm your clinical suspicion about the cause of the dog’s signs?
CT scan of the thorax
Tension response test
Bronchoalveolar lavage and culture
MRI of the brain
Myelogram
The correct answer is a Tensilon (edrophonium) response test. Hopefully, you were able to identify the mass in the cranial mediastinum on the chest radiograph, as this was one of the keys to this case. This, in conjunction with the dog’s other signs, are suggestive that this dog has a thymoma and associated secondary myasthenia gravis. Tensilon (edrophonium) is a rapidly acting anticholinesterase that reverses signs of myasthenia within minutes in most dogs.
A chest CT would be a valid test to confirm the presence of the mediastinal mass and might be an appropriate test before surgery but would not bring you closer to a diagnosis if you already have identified the mass. An MRI of the brain would assess a CNS cause of the dog’s signs, which are unlikely, given the other findings. Similarly, a myelogram would assess if a spinal cord lesion caused the dog’s signs, but the rest of the findings in this case should point you in a different direction.
A 5 year old male castrated German Shepherd Dog presents for a right thoracic limb monoplegia after jumping out of the back of a moving pickup truck. On physical exam, you observe superficial abrasions over his body, a right sided Horner’s syndrome, and dragging of his right thoracic limb. He has no conscious proprioception, motor function, or deep pain anywhere in the right thoracic limb. What should you tell the owner?
The dog has damage to the radial nerve. Electrodiagnostic procedures should be run to determine how much nerve function remains in the limb.
The dog has a brachial plexus avulsion but will likely regain function in the limb in several months.
The dog suffered a brachial plexus avulsion and will most likely need to have the leg amputated.
Physical therapy will greatly improve the chances that the dog will regain function of the limb.
The correct answer is the dog suffered a brachial plexus avulsion and will most likely need to have the leg amputated. Dogs that are hit by cars or who jump out of moving cars often suffer brachial plexus avulsions. Complete nerve root avulsions are not treatable and usually require amputation of affected limbs. Partial avulsions carry a better prognosis but require large amounts of time and physical therapy before seeing any improvement. The lack of deep pain and motor function in the limb is a negative prognostic indicator supporting the diagnosis of a complete brachial plexus avulsion.
Which of the following is the most common presentation for a patient with idiopathic epilepsy?
A 5-month old Yorkshire Terrier that has generalized tonic-clonic seizures, often after eating. The dog is sometimes obtunded between seizures.
X A 2-month old Chihuahua that presents in status epilepticus after vomiting and not eating for a day. This is the first seizure the dog has been observed having.
A 3-year old Labrador Retriever that recently began having generalized tonic-clonic seizures approximately once weekly, most frequently at night when resting. The dog appears and behaves normally between seizures.
A 9 year old Bexer that recently began having focal meter seizures that began weekly but are now becoming mere severe and frequent
Despite the term, idiopathic epilepsy refers to a specific condition and should not be applied to any patient with seizures of unknown cause. Most dogs with idiopathic epilepsy begin having seizures between 1 and 5 years of age. Breeds commonly affected include Beagles, Keeshonds, Dachshunds, Labrador and Golden Retrievers, Shetland Sheepdogs, Irish Wolfhounds, Vizslas, and English Springer Spaniels.
Idiopathic epilepsy is much less common in cats.
While not always the case, the classic descriptions of patients with idiopathic epilepsy describe generalized tonic-clonic seizures without interictal abnormalities with seizures beginning during the 1 to 5 year age range.
The Yorkshire Terrier described shows signs most consistent with a portosystemic shunt.
The Chihuahua described shows signs most consistent with hypoglycemia.
The Boxer’s signalment and signs are most consistent with intracranial neoplasia.
You have a 6-kg cat that you wish to raise his PCV from 15 to 25%. You plan to administer packed red blood cells. How many milliters of packed red blood cells will this cat need?
30 ml
60 ml
15 ml
120 ml
The correct answer is 60 ml. In order to raise the PCV 1% you will need to give 1ml/kg of packed red blood cells. So it takes 6mls to raise this cat’s PCV by 1%. If we are going to increase it by 10% we will need 60ml of packed red blood cells.
A 12-year-old female spayed Siamese cat presents for weight loss and progressive vomiting of 2 months duration. On physical exam, the intestines feel diffusely thickened and the cat has a body condition score of 2/9. Blood work shows a low albumin of 1.9 g/dL (normal 2.4-3.9 g/dL), and normal kidney and thyroid values. Abdominal ultrasound confirms the diffusely thickened intestines. There are also several mildly prominent and hypochoic mesenteric lymph nodes. You suspect the cat has cancer. What is the most appropriate treatment for the type of cancer you suspect in this patient?
Chlorambucil and prednisolone
Radiation therapy
Cyclophosphamide, vincristine, doxorubicin, and prednisone
Surgical resection
Carboplatin
The cat most likely has small cell or low-grade intestinal lymphoma based on the history and clinical findings. This is considered an indolent or slowly progressive form of lymphoma and can be effectively treated with chlorambucil and prednisolone. This form of lymphoma is sometimes thought to develop from the progression of inflammatory bowel disease in cats. Chlorambucil is an oral alkylating agent that is usually well tolerated with few side effects. Many cats can live several years with this form of lymphoma and this treatment.
Cyclophosphamide, vincristine, doxorubicin, and prednisone are the drugs in a CHOP chemotherapy protocol used to treat dogs and cats (and people) with high grade or large cell lymphoma, which more commonly manifests as a large focal mass rather than diffusely thickened intestines.
Surgery and radiation therapy are not good treatment options due to the diffuse nature of the cancer.
Carboplatin is not known to be an effective chemo agent for low-grade lymphoma in cats.
A 7 year old Bull Mastiff presents to your clinic with a complaint of lethargy. Physical exam is unremarkable. A CBC shows a markedly elevated white blood cell count of 150,000/ul (5,000-14,100/ul), consisting mostly of lymphocytes and unclassifiable circulating cells. You are concerned about the possibility of leukemia and elect to perform a bone marrow aspirate. You decide to use propofol for sedation/anesthesia in order to perform the brief procedure. Which of these should you monitor most carefully at induction with this agent?
Heart rate
Eye position
Respiration
Blood pressure
Propofol’s most common adverse side effect is temporary apnea. You should always be prepared to intubate and ventilate a patient when administering propofol due to the potential for severe apnea. It is certainly not wrong to monitor blood pressure and heart rate to assess anesthetic depth and vital signs, even for a brief procedure; but by far, the most important thing to watch is respiration.
For what type of surgery would nitrous oxide be contraindicated for use as part of an anesthetic protocol in a dog?
Splenic surgery
Open chest surgery
Hepatic surgery
Renal surgery
Gastrointestinal surgery
Explanation
The correct answer is gastrointestinal surgery. Nitrous oxide moves into closed gas spaces such as the intestines. As such, its use is contraindicated in bowel surgeries.
You should also be aware that nitrous oxide decreases fractional inspired oxygen levels although this can be managed and monitored in most instances. Nitrous oxide is contraindicated when pathology such as pulmonary bullae are present.
You ask your technician to give a 1 ml/kg dose of lidocaine to a dog that is having ventricular premature complexes. You realize after it is too late that she miscalculated the dose and gave 10 times what you asked for. What is the most common early sign of lidocaine toxicity in dogs?
Peripheral neuropathy
Central nervous system depression
Profound bradycardia
Anaphylaxis
Apnea
In dogs, toxicity of lidocaine is manifest primarily as CNS signs. Drowsiness or agitation may progress to muscle twitching and convulsions at higher doses. This occurs before respiratory or cardiac depression. Hypotension may develop if an IV bolus is given too rapidly.
Cats are more sensitive to lidocaine toxicity and may show cardiac suppression and CNS excitation.
You have just arrived at the clinic at which you are working, and a clinician promptly approaches you and informs you that your Bichon Frise patient’s CVP (central venous pressure) is -1 cmH2O. What is your assessment of the animal’s condition?
CVP is not a good measure of circulating volume
The animalis hypovolemic
Normal
Overhydrated
The correct answer is the animal is hypovolemic. CVP is a decent measure of circulating volume. A normal CVP can range from 0-10 mH2O. It is important to interpret the CVP in light of your patient’s clinical signs and to observe the trend in CVP measurements.
Which anesthetic agent is implicated in malignant hyperthermia?
Ketamine
Nitric oxide
Halothane
Acepromazine
The correct answer is halothane. This is mainly an entity in swine but may be seen in other animals. It is a rare induction of a hyper-metabolic reaction in skeletal muscle of susceptible individuals by halothane. The syndrome is characterized by muscle rigidity, increased body temperature, increased oxygen consumption and production of CO2.
Which of the following drugs and potential side effects are paired correctly together?
L-asparaginase - anaphylaxis
Doxorubicin - cystitis
Vincristine - cardiac toxicity
Lomustine - pancreatitis
L-asparaginase is a protein enzyme and therefore may elicit an immune response. Anaphylaxis is rare but usually would occur only after a patient had received a prior dose and developed antibodies to it.
Vincristine is associated with paralytic ileus.
Lomustine is associated with hepatotoxicity.
Doxorubicin is associated with cardiotoxicity.
Cystitis is associated with cyclophosphamide.
Pancreatitis is associated with L-asparaginase or doxorubicin.