Which of these nerve blocks is used to examine the eyes of a horse?
A- Oculomotor nerve block
B- Trigeminal nerve block
C- Auriculopalpebral nerve block
D- Corneal nerve block
Give this one a try later!
C- Auriculopalpebral nerve block
The correct answer is auriculopalpebral nerve block. Blocking this branch
of cranial nerve VII (facial nerve) disrupts the motor innervation to the
orbicularis oculi, which is the muscle that closes the eye. In the horse, this
muscle is very strong and can prevent a thorough ocular exam. To perform
this block, lidocaine is injected subcutaneously at the caudal aspect of the
zygomatic arch where the nerve is palpable. Because this is a motor nerve,
the eye will not be able to close as well, but there is no anesthesia of the
tissue.
,A three-year-old female goat presents in poor body condition, slightly
depressed, and febrile. The goat is mildly pruritic.
The skin shows mild to moderate erythema and alopecia and marked
hyperkeratosis and crusting on all four extremities, as shown in the
image below.Skin scrapings are negative for mites.
A cytology taken from the underside of a crust shows parallel stacks
or rows of cocci ("railroad tracks") between keratinocytes, also shown
below.
Which one of the following choices is the most likely diagnosis?
A - Streptococcus infection
B - Malassezia dermatitis
C - Dermatophytosis
D - Pyoderma
E - Dermatophilosis
Give this one a try later!
, E - Dermatophilosis
Dermatophilosis is a crusting dermatitis caused by the filamentous bacteria
Dermatophilus congolensis, seen in all ruminants and horses. Also called
“lumpy wool” or “rain scald/rot.”
Infection is seen most often in younger or systemically
ill/immunocompromised animals. Many are housed in areas with poor
hygiene or without shelter. Excessive moisture, rainy conditions, skin
damage, and concurrent illness that results in immunosuppression are
predisposing factors.
Loss of the protective sebaceous film layer seen on healthy skin is thought
to be an important factor in the pathogenesis. Carrier animals and fomites
such as grooming tools are also important as this can be contagious in at-
risk animals.
Thick crusts, which usually contain the organism, look like the end of a paint
brush when removed from the animal and are a typical finding. On cytology
(impression smear of a crust) the "railroad track" appearance of the gram-
positive cocci is classic for dermatophilosis.
The infection self-resolves after a few weeks in most animals without
treatment. Can use topical and systemic antimicrobials in persistent cases.
A 4-year old female spayed Siberian Husky presents for further
evaluation as a result of developing crusting and hyperkeratosis
around the eyes, nose, and mouth. A skin scraping did not identify an
etiology. How would you treat this dog?
Daily wiping with chlorhexidine pads
Corticosteroids
Zinc supplementation
Ivermectin treatment
Give this one a try later!
, Zinc supplementation
Zinc responsive dermatopathy occurs most frequently in the Siberian
Husky. Other species such as cattle, goats, and humans have a similar
condition. The exact cause is unknown, but it has been linked to defective
intestinal absorption of zinc. Lesions may vary in severity. The response is
typically seen within days. The key to answering this question appropriately
was to recognize the signalment of the patient, the location of the lesions
which is characteristic of zinc responsive dermatopathy, and the fact that
there was no infectious etiology such as demodex identified.
In which species is the appearance of these red blood cells a normal
finding?
A - Equine, feline
B - Porcine, lagomorph
C - Ovine, reptile
D - Avian, caprine
E - Rodent, bovine
Give this one a try later!
A - Equine, feline
This is red blood cell (RBC) stacking, a.k.a. rouleaux formation, on a feline
blood smear; this is a normal finding in cats and horses.
Always differentiate normal rouleaux formation from RBC agglutination,
which is not normal.
Here is more useful information from Cornell's eClinPath website about
RBC agglutination and rouleaux formation).
Here is equine rouleaux formation (note the characteristic equine
eosinophil at the top).
Remember, normal goats may have marked poikilocytosis; camelids have
ellipsoid RBC; and normal RBCs in birds and reptiles are nucleated.
A- Oculomotor nerve block
B- Trigeminal nerve block
C- Auriculopalpebral nerve block
D- Corneal nerve block
Give this one a try later!
C- Auriculopalpebral nerve block
The correct answer is auriculopalpebral nerve block. Blocking this branch
of cranial nerve VII (facial nerve) disrupts the motor innervation to the
orbicularis oculi, which is the muscle that closes the eye. In the horse, this
muscle is very strong and can prevent a thorough ocular exam. To perform
this block, lidocaine is injected subcutaneously at the caudal aspect of the
zygomatic arch where the nerve is palpable. Because this is a motor nerve,
the eye will not be able to close as well, but there is no anesthesia of the
tissue.
,A three-year-old female goat presents in poor body condition, slightly
depressed, and febrile. The goat is mildly pruritic.
The skin shows mild to moderate erythema and alopecia and marked
hyperkeratosis and crusting on all four extremities, as shown in the
image below.Skin scrapings are negative for mites.
A cytology taken from the underside of a crust shows parallel stacks
or rows of cocci ("railroad tracks") between keratinocytes, also shown
below.
Which one of the following choices is the most likely diagnosis?
A - Streptococcus infection
B - Malassezia dermatitis
C - Dermatophytosis
D - Pyoderma
E - Dermatophilosis
Give this one a try later!
, E - Dermatophilosis
Dermatophilosis is a crusting dermatitis caused by the filamentous bacteria
Dermatophilus congolensis, seen in all ruminants and horses. Also called
“lumpy wool” or “rain scald/rot.”
Infection is seen most often in younger or systemically
ill/immunocompromised animals. Many are housed in areas with poor
hygiene or without shelter. Excessive moisture, rainy conditions, skin
damage, and concurrent illness that results in immunosuppression are
predisposing factors.
Loss of the protective sebaceous film layer seen on healthy skin is thought
to be an important factor in the pathogenesis. Carrier animals and fomites
such as grooming tools are also important as this can be contagious in at-
risk animals.
Thick crusts, which usually contain the organism, look like the end of a paint
brush when removed from the animal and are a typical finding. On cytology
(impression smear of a crust) the "railroad track" appearance of the gram-
positive cocci is classic for dermatophilosis.
The infection self-resolves after a few weeks in most animals without
treatment. Can use topical and systemic antimicrobials in persistent cases.
A 4-year old female spayed Siberian Husky presents for further
evaluation as a result of developing crusting and hyperkeratosis
around the eyes, nose, and mouth. A skin scraping did not identify an
etiology. How would you treat this dog?
Daily wiping with chlorhexidine pads
Corticosteroids
Zinc supplementation
Ivermectin treatment
Give this one a try later!
, Zinc supplementation
Zinc responsive dermatopathy occurs most frequently in the Siberian
Husky. Other species such as cattle, goats, and humans have a similar
condition. The exact cause is unknown, but it has been linked to defective
intestinal absorption of zinc. Lesions may vary in severity. The response is
typically seen within days. The key to answering this question appropriately
was to recognize the signalment of the patient, the location of the lesions
which is characteristic of zinc responsive dermatopathy, and the fact that
there was no infectious etiology such as demodex identified.
In which species is the appearance of these red blood cells a normal
finding?
A - Equine, feline
B - Porcine, lagomorph
C - Ovine, reptile
D - Avian, caprine
E - Rodent, bovine
Give this one a try later!
A - Equine, feline
This is red blood cell (RBC) stacking, a.k.a. rouleaux formation, on a feline
blood smear; this is a normal finding in cats and horses.
Always differentiate normal rouleaux formation from RBC agglutination,
which is not normal.
Here is more useful information from Cornell's eClinPath website about
RBC agglutination and rouleaux formation).
Here is equine rouleaux formation (note the characteristic equine
eosinophil at the top).
Remember, normal goats may have marked poikilocytosis; camelids have
ellipsoid RBC; and normal RBCs in birds and reptiles are nucleated.
