FC To Review Flashcards
There are 5 steps along the pain pathway to alert a patient to a painful stimulus.
Which of the following is the step that turns a noxious stimulus into an electrical signal in nerves, which then along the pathway is perceived as pain?
Transmission
Transduction
Perception
Projection
Modulation
Answer: Transduction
Transduction is the conversion of a stimulus, usually mechanical, thermal, or chemical, into an electrical signal by pain receptors located on nerve endings in the skin, subcutaneous tissues, viscera, etc.
The electrical impulse is transmitted via afferent sensory nerves to the dorsal horn of the spinal cord.
This is where the response to the painful stimulus is directed, when appropriate (e.g., a withdrawal reflex), or amplified, facilitated and/ or suppressed here (i.e., modulation).
The signal is then projected to higher centers, usually via the spinothalamic or the spinoreticular tracts. Further modulation occurs in the thalamus, reticular formation, and limbic system.
Finally, it reaches the cerebral cortex, where perception produces physical and emotional responses.
Which one of the following regional nerve blocks does not affect sensory function but blocks motor function of the upper eyelid, and is indicated to allow complete ophthalmic examination in the horse?
Supraorbital
Ocular
Zygomatic
Auriculopalpebral
Frontal
Answer: Auriculopalpebral
The auriculopalpebral nerve, located along the dorsal zygomatic arch of the eye, provides motor innervation to the upper orbicularis oculi muscle.
Anesthesia of this nerve prevents the horse from being able to blink the eye and facilitates complete ophthalmic examination.
The frontal nerve is a branch of the trigeminal nerve and provides sensory innervation to the upper eyelid.
Click here to see a good summary on ophthalmology surgical emergencies in horses, with images, courtesy of the American College of Veterinary Surgeons (ACVS).
Refs: Smith, Large Animal Internal Medicine, 4th ed. pp. 793-8.
Auriculopalpebral Block in Equine Medicine
Definition
• Auriculopalpebral Block: A local anesthetic technique used to block the auriculopalpebral nerve, facilitating ophthalmic procedures by preventing eyelid movement.
Purpose
• Indications: Used for ocular examinations, minor surgical procedures around the eye, and alleviating blepharospasm. • Mechanism: Blocks motor function of the orbicularis oculi muscle, causing temporary paralysis of the upper eyelid.
Procedure
• Technique: Administer local anesthetic (e.g., lidocaine) near the auriculopalpebral nerve at the zygomatic arch. • Effect: Immediate eyelid immobility lasting for approximately 1-2 hours.
https://www.acvs.org/large-animal/ophthalmology-surgical-emergencies-in-horses/
Which combination is the safest and most humane anesthetic protocol for ovariohysterectomy in a dog or cat?
Midazolam, ketamine, atropine
Lidocaine, carprofen, etomidate
Butorphanol, acepromazine, sevoflurane
Dexmedetomidine, glycopyrrolate,
bupivacaine, hydromorphone
Morphine, diazepam, propofol, isoflurane
Answer: Morphine, diazepam, propofol, isoflurane
Use a combination of an analgesic (e.g., morphine), anxiolytic (e.g., diazepam), intravenous induction agent (e.g., propofol), and inhalant anesthesia (e.g., isoflurane) to provide the safest, most humane protocol for ovariohysterectomy (OHE) in a dog or cat.
Combining multiple agents, known as multimodal anesthesia, greatly improves pain and stress control.
Examples of common analgesics include opioids and non-steroidal anti-inflammatories (NSAIDs). Commonly used anxiolytics include acepromazine, benzodiazepines (e.g., midazolam, diazepam), and alpha-2 adrenergic agonists (e.g., dexmedetomidine).
Remember, not all anxiolytics and anesthetics have analgesic properties. Failure to provide adequate analgesia results in pain and a requirement for higher doses of other anesthetic agents, which increases the risk of cardiovascular side effects.
Do not use inhalant anesthesia (i.e., mask induction) alone for induction. It causes increases both in patient stress and risk of significant cardiovascular depression and aspiration pneumonia due to an unprotected airway. Use inhalant agents for anesthetic maintenance following induction with an injectable anesthetic or consider total intravenous anesthesia.
What is the U.S. Drug Enforcement Agency controlled schedule for the anesthetic drug alfaxalone?
Answer: IV
Alfaxalone is a U.S. Drug Enforcement Agency (DEA) schedule IV controlled substance.
Alfaxalone is a neuroactive steroid used in cats and dogs for the induction and maintenance of general anesthesia. It may be administered IV or IM and, similar to propofol, it does not provide any analgesia.
The DEA schedules drugs into one of five categories based on their accepted medical use and the abuse/dependence potential.
Schedule I drugs have a high risk for abuse and are the most restricted. Schedule V drugs have the least potential for abuse.
Which part of a cow’s digestive system has many folds in the lining, like leaves or the pages in a book?
Abomasum
Omasum
Rumen
Reticulum
Cecum
Answer: Omasum
The omasum is composed of many layers of folds, which look like leaves or pages in a book. These increase fluid absorption.
There are four compartments in the ruminant stomach: reticulum, rumen, omasum (together comprising the “forestomachs”), and abomasum.
The rumen and reticulum contain microorganisms to ferment and digest nutrients (hence the term “forestomach” fermenters vs. horses are considered “hindgut fermenters” because their large colon and cecum serve this purpose). The abomasum is a glandular “true” stomach that contains acid for further digestion.
Which part of a cow’s digestive system has many folds in the lining, like leaves or the pages in a book?
Abomasum
Omasum
Rumen
Reticulum
Cecum
Answer: Omasum
The omasum is composed of many layers of folds, which look like leaves or pages in a book. These increase fluid absorption.
There are four compartments in the ruminant stomach: reticulum, rumen, omasum (together comprising the “forestomachs”), and abomasum.
The rumen and reticulum contain microorganisms to ferment and digest nutrients (hence the term “forestomach” fermenters vs. horses are considered “hindgut fermenters” because their large colon and cecum serve this purpose). The abomasum is a glandular “true” stomach that contains acid for further digestion.
A three-year-old Dachshund presents with acute onset of severe thoracolumbar pain, arched back, and hypermetria, ataxia, and weakness in the pelvic limbs. Ambulation is normal in the thoracic limbs.
The cutaneous trunci reflex caudal to T13 is absent on the right and absent caudal to L3 on the left.
Of the following choices, where is the likely location of this dog’s lesion?
T11-12, mostly right side
C7-T1 mostly right side
L7-S1 mostly left side
Cannot determine without more information
L2, mostly left side
Answer: T11-12 mostly right side
This dog’s lesion is roughly at T11-12, mostly on the right. The loss of the cutaneous trunci reflex occurs about 1-4 (usually 2) spinal cord segments caudal to the actual lesion.
Dorsal cutaneous branches do not exit the spinal cord at around
L3-4 so the the loss of the reflex on the left at L3 is normal.
The lateral thoracic nerve, which innervates the ipsilateral cutaneous trunci muscle, exits the spinal cord at C7-1. So with a brachial plexus avulsion you may see an ipsilateral loss of the cutaneous trunci response (“twitching”) while lightly pinching on the skin on the ipsilateral side, however the contralateral side will respond!
Cutaneous Trunci Reflex in Veterinary Neurology
Definition
The cutaneous trunci reflex is a test to assess the integrity of the spinal cord, particularly the thoracolumbar region.
Procedure
• Method: Gently squeeze the skin lateral to the spine with a hemostat, starting from the lumbosacral region and moving cranially. • Normal Response: Bilateral contraction of the cutaneous trunci muscles, resulting in a skin twitch over the thorax and abdomen.
Clinical Significance
• Lesion Localization: Absence of reflex caudal to a lesion, while the reflex remains normal cranial to it. • LMN Involvement: Indicates involvement of the lateral thoracic nerve (C8-T2 spinal segments).
Application
• Use: Useful for diagnosing spinal cord injuries and differentiating them from peripheral nerve injuries.
Which one of the following sites would be the most appropriate to place an intraosseous catheter in a bird?
Ulna
Humerus
Synsacrum
Femur
Coracoid
Answer: Ulna
The distal ulna is the site most frequently utilized for an intraosseous catheter in birds. The proximal tibiotarsal bone is another frequent site.
Do NOT use the humerus and femur. They are pneumatized bones and would deliver fluids into the respiratory tract, essentially drowning the bird.
What is clinical significance of the reciprocal apparatus?
Maintains balance when one leg is off the ground
Neuromotor mechanism behind pupillary light reflex
Allows a horse to rest while standing
Ensures coordination of movement between eyes
Flexion in stifle causes flexion in hock
Answer: Flexion in stifle causes flexion in hock
The reciprocal apparatus of the pelvic limb means that flexion in stifle causes flexion in hock. It consists of the fibularis (peroneus) tertius muscle on the cranial aspect of the crus and the superficial digital flexor on the caudal aspect.
Because of these two opposing “cords,” flexion or extension of the tarsus (hock) or stifle will cause a reciprocal flexion or extension of the other joint.
Don’t confuse the reciprocal apparatus with the STAY apparatus, a combination of non-tiring tendons and ligaments on both the fore and hind limbs that allow muscle bellies to bypass tension so that a horse may rest while standing with little fatigue.
Click here to see the stifle locking mechanism of the stay. apparatus, courtesy of the Atlanta Equine Clinic.
Which of the following structures is marked with the yellow circle?
Spermatids
Seminiferous tubule
Tunica albuginea
Leydig cell
Intersitium
Answer: Seminiferous tubule
The entire structure outlined in yellow is a seminiferous tubule of a testis, where spermatogensis occurs. #1 is the lumen of the tubule.
Leydig cells (#7, also called interstitial cells) are located in the intersitium between the seminiferous tubules.
The Leydig cells produce most of the body’s testosterone in response to luteinizing hormone secreted from the pituitary.
Sertoli cells are indicated by #5. These are also called “nurse” cells because they produce hormones and proteins to facilitate spermatogenesis.
What are the anatomic structures that comprise the umbilical o cord in a foal?
Two umbilical arteries, one umbilical vein, and two urachi
One umbilical vein, two umbilical arteries, and one urachus
One umbilical artery, two umbilical veins, and two urachi
Two umbilical arteries, two umbilical veins, and two urachi
Two umbilical veins, one umbilical artery, and one urachus
Answer: One umbilical vein, two umbilical arteries, and one urachus
The umbilical cord of a foal is comprised of one umbilical vein, two umbilical arteries, and one urachus.
The umbilical vein brings nutrient- and oxygen-rich blood from the placenta to the fetus; it enters the fetal liver to join the portal vein.
The umbilical arteries are the vascular return from fetus to dam.
They originate off of the internal pudendal artery and pass ventrally on either side of the bladder.
The urachus is the tubular connection present in the fetus between the bladder and the umbilicus. During gestation, urine flows from the bladder through the urachus into the allantoic sac.
As the fetus gets closer to term, more and more urine flows through the urethra, until ideally at birth all urine exits the bladder through the urethra and the urachus should involute.
Which one of the following organisms is typically implicated in verminous myelitis in horses?
Sarcocystis neurona
Stephanurus dentatus
Cuterebra spp.
Strongylus vulgaris
Baylisascaris procyonis
Answer: Strongylus vulgaris
Strongylus vulgaris is the most common helminth associated with verminous myelitis (aberrant helminth migration) in horses. Signs vary, but are usually acute and asymmetric and may be progressive.
Possible organisms include:
Strongylus vulgaris, Halicephalobus (Micronema) deletrix, and Setaria spp. - horses
Parelaphostrongylus tenuis - sheep, goats, llamas
Hypoderma bovis - cattle
Stephanurus dentatus - pigs
Cuterebra spp. - cats
Baylisascaris procyonis - dogs and humans
Don’t confuse equine protozoal myeloencephalitis (EPM), caused by Sarcocystis neurona (and, less commonly, Neospora hughesi) with verminous myelitis caused by helminths (worms).
How would you change exposure settings to make an x-ray film lighter?
Increase kVp, decrease mA, increase time
Increase kVp, increase mA, increase time
Decrease KVp, decrease mA, decrease time
Decrease kVp, increase mA, increase time
Decrease the film-focal distance
Answer: Decrease KVp, decrease mA, decrease time
To make a film lighter, decrease kilovoltage (KVp), milliamperes (mA), or time (seconds).
Decreasing milliampere-seconds (mAs) decreases the number of photons hitting the film, which exposes it less.
Lower kVp decreases photon energy (penetrating power of the x-rays through tissue).
Shorter time generates fewer electrons which also decreases exposure and therefore decreases darkness on the X-ray film once it is developed.
A four-year-old male neutered domestic shorthair cat is presented for left thoracic limb lameness. He is an indoor-outdoor cat who was normal four days ago. The owner noted the lameness upon returning from a trip out of town.
Physical exam reveals left carpal swelling, radiographs of the area are shown below.
What pathological process is most likely?
Neoplasia
Congenital malformation
Infection
Osteochondrosis
Projectile foreign body (shotgun pellet)
Answer: Infection
The joint-crossing lytic damage seen between the carpal joint and fourth and fifth metacarpal bones is consistent with osteomyelitis (infection), although biopsy for histopathology and culture is required for definitive diagnosis. Osteomyelitis may be bacterial or fungal in origin.
In chronic osteomyelitis that does not respond to medical management amputation maybe the best Tx option.
Bone tumors, such as osteosarcoma, usually do not cross the joint.
A four-year-old male neutered domestic shorthair cat is presented for left thoracic limb lameness. He is an indoor-outdoor cat who was normal four days ago. The owner noted the lameness upon returning from a trip out of town.
Physical exam reveals left carpal swelling, radiographs of the area are shown below.
What pathological process is most likely?
Neoplasia
Congenital malformation
Infection
Osteochondrosis
Projectile foreign body (shotgun pellet)
Answer: Infection
The joint-crossing lytic damage seen between the carpal joint and fourth and fifth metacarpal bones is consistent with osteomyelitis (infection), although biopsy for histopathology and culture is required for definitive diagnosis. Osteomyelitis may be bacterial or fungal in origin.
In chronic osteomyelitis that does not respond to medical management amputation maybe the best Tx option.
Bone tumors, such as osteosarcoma, usually do not cross the joint.
Which two organisms are most associated with early embryonic
loss and infertility in cattle?
Neosporosis, Listeria monocytogenes
Mycoplasma bovis, Foothill abortion
Actinomyces pyogenes, bovine viral diarrhea
Leptospira hardjo, Aspergillus fumigatus
Tritrichomonas foetus, campylobacteriosis
Answer: Tritrichomomas foetus, campylobacteriosis
Campyplobacteriosis and Tritrichomonas foetus are associated with early embryonic loss and infertility in cattle.
Bovine genital campylobacteriosis (Campylobacter fetus sbsp. venerealis) primarily causes venereal disease that leads to infertility. Occasionally it can cause late abortions too, but most commonly it causes infertility.
Bovine trichomoniasis ( Tritrichomonas foetus) causes early embryonic loss in cattle.
Both diseases have similar presentations.
Which of these organism choices has a reproductive cycle cats ?
Toxoplasma gondii
Haemophilus influenzae
Brachyspira hyodysenteriae
Neorickettsia helminthoeca
Mycobacterium avium sbsp. paratuberculosis
Answer: Toxoplasma gondii
Toxoplasma gondii has a reproductive cycle in cats.
Toxoplasmosis is a multisystemic protozoal disease that affects primarily young animals and the immunosuppressed (think cats with FIV, humans on chemotherapy).
T. gondi is an important cause of abortion in sheep, goats, and sometimes pigs.
A young calf is presented for lameness with a hot, swollen left hock.
What is the most likely etiology of this finding?
Staphylococcus aureus
Umbilical infection
Liver abscess
Damaged skin over lateral condyle
Kick wound from pen-mate
Answer: Umbilical infection
Cases of septic arthritis in calves/foals/lambs most often occur from hematogenous spread following an umbilical infection.
Also called “navel ill” or “omphalophlebitis,” infection of the umbilical stump/remnants is a common condition in neonatal large animals.
Treatment can be medical (long-term antimicrobials) or surgical (removal of infected structures + antimicrobials).
Arthritis in Large Animals - Comprehensive Study Guide
Definition
• Arthritis: Inflammation of joints, including traumatic arthritis, osteochondritis dissecans, subchondral bone cysts, septic arthritis, and osteoarthritis.
Types and Causes
• Traumatic Arthritis: Resulting from injuries like fractures, ligament tears, and cartilage trauma. • Osteochondritis Dissecans (OCD): Defect in endochondral ossification, leading to cartilage flaps and cysts. • Subchondral Bone Cysts: Result from osteochondrosis or trauma. • Septic Arthritis: Bacterial infection via hematogenous spread, trauma, or iatrogenic causes. • Osteoarthritis: Chronic degeneration due to wear and tear, untreated joint injuries, or infections.
Symptoms
• General: Lameness, joint pain, synovial effusion, joint deformity, and decreased range of motion. • Specific Signs: Depends on the type and severity of arthritis.
Diagnosis
• Methods: Clinical examination, radiography, ultrasonography, arthroscopy, synovial fluid analysis, and serologic tests.
Treatment
• Medical: Rest, NSAIDs (e.g., phenylbutazone), corticosteroids (e.g., betamethasone, triamcinolone), hyaluronic acid, polysulfated glycosaminoglycans (PSGAGs), antibiotics for septic cases. • Surgical: Arthroscopic removal of osteochondral fragments, repair of major fractures, and joint lavage for septic arthritis.
Prevention and Management
• Preventive Measures: Proper nutrition, controlled breeding, injury prevention, early treatment of joint injuries. • Long-term Management: Regular monitoring, appropriate use of medications, and possible surgical interventions.
CGPT: Specific Diseases Associated with Sepsis in Foals
Which one of the following nutritional factors is associated with the development of osteochondrosis in young horses?
Copper deficiency
Zinc deficiency
General undernutrition/starvation
Early weaning
Calcium deficiency
Answer: Copper deficiency
Copper deficiency has been associated with osteochondrosis.
Osteochondrosis is an important developmental disorder of articular cartilage in horses and many other animals.
Osteochondrosis is thought to be the result of a focal disturbance in endochondral ossification. The etiology is multifactorial, including rapid growth, overnutrition, mineral imbalance, genetic influences, and cartilage trauma. When the diseased cartilage is inflamed and separates from the underlying bone it is called OCD.
Clinical signs are effusion of affected joints and potentially lameness or, rarely, neurologic signs (if cervical lesion).
Management may be conservative for mild cases (restricted exercise, reduction in feed intake, correction of mineral imbalances) or surgical for more advanced lesions.
A 3-year-old female spayed Labrador retriever is presented in southern Alabama for a suspected snakebite. The owner thinks the bite may have occurred during their morning walk an hour ago.
The dog appears clinically normal. The owner killed the snake and brought it for identification: it is an eastern coral snake.
Which of the following abnormalities is most likely if envenomation happened?
Hemolysis, paralysis
Coagulopathy, severe swelling around the bite
Hypernatremia, hemorrhagic diarrhea
Seizures, hypoglycemia
Muscle rigidity, hyperkalemia
Answer: Hemolysis, paralysis
Expect hemolysis, lower motor neuron paralysis, and mental depression with coral snake (Micrurus spp.) envenomation. Clinical signs can progress extremely rapidly (within minutes) to the point of respiratory paralysis, necessitating mechanical ventilation. But onset of clinical signs can be delayed up to 36 hours!
In contrast, pit viper envenomation is most commonly associated with coagulopathy and rapid, severe swelling around the bite.
Coral snake bites are far less common than those of pit vipers (rattlesnakes, copperheads, cottonmouths) due to their limited geographic distribution.
Click here to see an image of an eastern coral snake. Think âRed-on-yellow, kill a fellow. Red-on-black, friend of Jackâ to remember which snakes are poisonous.
What is the definitive treatment for heartworm disease in a cat?
Melarsomine
None
Milbemycin
Ivermectin
Corticosteroids
Answer: None
There is no definitive treatment for Dirofilaria immitis (heartworm) infection in cats. In dogs, melarsomine is the treatment for adult heartworms and ivermectin or milbemycin are the treatments for microfilariae.
There is no safe dose of melarsomine in cats.
Corticosteroids may be used to help treat interstitial lung disease and vomiting in cats that can occur secondary to heartworm infections. However, steroids treat clinical signs, not the underlying disease.
Heartworm Disease in Cats - Comprehensive Study Guide
Definition
• Heartworm Disease: Caused by Dirofilaria immitis, primarily affects the pulmonary arteries, causing severe pulmonary inflammation and sometimes sudden death in cats.
Causative Agent
• Dirofilaria immitis: Filarial nematode transmitted by mosquitoes.
Pathophysiology
• Lifecycle: Microfilariae develop into infective larvae inside mosquitoes, transmitted to cats through mosquito bites. Larvae migrate to the pulmonary arteries, where they mature and cause inflammation. • Host Response: Cats can have a severe immune reaction to both juvenile and adult worms, leading to heartworm-associated respiratory disease (HARD).
Symptoms
• Early Signs: Coughing, dyspnea, vomiting, lethargy. • Advanced Signs: Acute respiratory distress, sudden death.
Diagnosis
• Tests: Antigen and antibody tests, thoracic radiography, echocardiography.
Treatment
• No Adulticides: Melarsomine is not used due to toxicity. • Management: Supportive care with corticosteroids, oxygen therapy, and bronchodilators. • Prevention: Monthly prophylaxis with macrocyclic lactones (ivermectin, milbemycin, moxidectin, selamectin).
Umbilical hernias may be more common in which one of the following bovine breeds?
Holstein
Hereford
Angus
Jersey
Brown Swiss
Answer: Holstein
Umbilical hernias are a common finding in neonatal calves, especially in calves of the Holstein breed.
They are typically easily reducible and uninfected. Infected masses may occur in any breed and be difficult to reduce and accompanied by other clinical signs such as heat in the area, drainage, fever, inappetance, and ill thrift.
It is possible to have infected umbilical remnants while the exterior umbilical structures appear completely normal, and deep palpation, ultrasound, and/or bloodwork may be necessary to rule out occult infections. Infections may also weaken the umbilical area and lead to hernias.
Tx: Surgical repair with resection of infected structures is the treatment of choice for umbilical hernias in the calf.
Click here to see a good summary on umbilical masses and hernias in calves, with images, courtesy of the American College of Veterinary Surgeons (ACVS).
A 17-year-old mare is presented for chronic left-sided nasal discharge of 2-3 months duration. The mare is bright and alert and in otherwise good body condition.
The discharge is white-yellow, thick, and malodorous. The left submandibular lymph node is mildly enlarged.
Which of the following would be an appropriate course of action?
Take skull radiographs
Antihistamines (hydroxazine); wet down hay prior to feeding
Obtain nasal swab for culture and PCR
Perform dental float
Submit serum to screen for strangles (Streptococcus equi equi)
Answer: Take skull radiography
Skull radiographs should be recommended for this horse with a likely sinus infection.
Radiographs may show fluid lines, abnormal tooth roots or fractured teeth, masses (e.g., sinus cysts, progressive ethmoid hematomas, tumors, granulomas), or abnormal bone associated with the underlying disease. Additional diagnostics include endoscopy, CT, sinoscopy, and thorough dental exam.
Chronic unilateral, malodorous (fetid), yellow-white discharge is highly suggestive of a sinus infection. Horses have six pairs of paranasal sinuses.
Sinus infections can be primary (associated with upper respiratory tract infection) or, more commonly, secondary (to tooth root infection, sinus cyst, sinus mass).
In horses, sinusitis is most often due to tooth root infections, since the roots of the four caudal-most cheek teeth extend into the maxillary sinus cavity.
Rx: Trephination and lavage of the sinus cavity with systemic antimicrobial therapy.
If sinusitis is secondary to a confirmed tooth root infection or mass (e.g., cyst) within the sinus, sinus flap with tooth repulsion or removal of abnormal material is indicated.
Click here for an excellent overview of sinusitis in horses with radiographic and surgical images, courtesy of the American College of Veterinary Surgeons (ACVS).
Omphalophlebitis in Foals - Comprehensive Study Guide
Definition
• Omphalophlebitis: Inflammation and infection of the umbilical vein, often leading to sepsis in neonatal foals.
Causative Agents
• Bacteria: Commonly include Escherichia coli, Klebsiella spp., Enterococcus spp., Streptococcus, and anaerobes like Bacteroides and Clostridium.
Pathophysiology
• Infection Process: Bacteria ascend through the umbilical stump into the umbilical veins, leading to local inflammation, abscess formation, and potential systemic infection.
Symptoms
• Clinical Signs: Swelling, heat, and pain around the umbilicus, purulent discharge, systemic signs of sepsis, fever, lethargy, and potentially signs of peritonitis or septic arthritis.
Diagnosis
• Techniques: Physical examination, ultrasonography to visualize umbilical structures, and bacterial culture from aspirated fluid or tissue samples.
Treatment
• Antibiotics: Systemic antibiotic therapy for 10-14 days based on culture and sensitivity results. • Local Treatment: Topical antiseptics such as silver nitrate or procaine penicillin G for the umbilical stump. • Surgery: Umbilical resection if there is significant abscessation or persistent infection.
Prognosis and Prevention
• Prognosis: Generally good with prompt and appropriate treatment, but severe cases with systemic involvement have a poorer prognosis. • Prevention: Good hygiene during and after birth, proper management of the umbilical stump, and regular monitoring of foals.
This 5-day-old calf was born normally to a primiparous dam, but was found down today.
The animal is stiff, has opisthotonos, and is hyperreactive to tactile, visual, and auditory stimuli.
There is no visual deficit, but the calf has inducible nystagmus which varies with changes in head position.
Movement of the neck triggers tonic clonic convulsions. Rectal temperature is 105.5°F (40.8°C)..[N=101.5-103.5°F, N=37.8-39.7°C].
Which one of the following choices is the most likely diagnosis?
Nervous coccidiosis
Polioencephalomalacia
Neosporosis
Bacterial meningitis
Bovine spongiform encephalopathy
Answer: Bacterial meningitis
Stiffness, inducible nystagmus, and intermittent tonic-clonic convulsions in a 5-day-old calf are indicative of bacterial meningitis.
These cases are hyperreflexive and extremely hyperesthetic.
Although this patient is still visual, blindness is often seen.
The fever is also typical of bacterial meningitis, and may be exacerbated by the seizures.
The causative agent is usually the bacterial organism E. coli which accesses the CNS hematogenously after entrance through the tonsils, especially in colostrum-deprived calves.
Failure of passive transfer is more common in calves born to primiparous dams.
A lumbosacral CSF tap can be performed to confirm the diagnosis.
Nervous coccidiosis is a disease of weaned calves approximately 3 to 5 months of age. The affected animals are usually comatose and non-visual.
This calf is young for polioencephalomalacia (PEM), and is not blind, a common clinical sign in PEM.
If the calf had neosporosis it might resemble this patient, but wouldn’t have a fever or hyperesthesia, and probably would have been born with the condition.
Bacterial Meningitis in Calves - Comprehensive Study Guide
Definition
• Bacterial Meningitis: Inflammation of the meninges due to bacterial infection, often leading to meningoencephalitis.
Causative Agents
• Common Bacteria: Escherichia coli, Streptococcus spp., Klebsiella spp., Salmonella spp., and Histophilus somni.
Pathophysiology
• Mechanism: Bacteria reach the meninges through hematogenous spread from primary infection sites like the umbilicus (navel-ill), respiratory tract, or gastrointestinal tract, causing inflammation, increased intracranial pressure, and neurologic damage.
Symptoms
• Early Signs: Fever, lethargy, poor suckle reflex, stiff neck, and hyperesthesia. • Advanced Signs: Seizures, opisthotonos, ataxia, and coma.
Clinical Changes
• Lesions: Purulent exudate on meninges, cloudy cerebrospinal fluid (CSF).
Diagnosis
• Methods: Clinical signs, CSF analysis (increased WBC count, protein concentration), culture, PCR.
Treatment
• Antibiotics: Broad-spectrum antimicrobials (e.g., ceftiofur, ampicillin) based on sensitivity. • Supportive Care: IV fluids, anti-inflammatory drugs (NSAIDs), and nutritional support.
Prevention
• Management: Good hygiene during birth, prompt treatment of primary infections, adequate colostrum intake, and vaccination where applicable.
What is the clinical presentation of human infection with Dirofilaria immitis?
Left-sided heart failure, congestion, ascites, weakness
Most have no obvious symptoms
Dirofilaria immitis does not infect humans
Acute type 1 hypersensitivity reaction
Renal insufficiency
Answer: Must have no obvious symptoms
Zoonotic transmission of heartworm (HW) to people does occur.
In humans infected with Dirofilaria immitis, dying worms in pulmonary artery branches can produce focal pulmonary. inflammation and granulomas. In spite of this, most people with pulmonary dirofilariasis show no obvious clinical signs.
Clinical signs in people may include cough (including coughing up blood), chest pain, fever, and pleural effusion. There are no reports of a human infection becoming patent.
Infective larvae may reach the lungs and become encapsulated before they die. This causes a granulomatous reaction known as
“coin lesions” appear similar radiographically to metastatic lung disease.
While vets should never advise their clients about diagnosis of human disease, it is important to understand zoonoses and be able to direct clients to seek medical attention.
A SNAP® heartworm antigen test with a reported sensitivity 96% and specificity of 98% is being used in dogs.
Assuming the prevalence of heartworm in the area is 10%, what is the predictive value negative (PVN) of the test?
99%
88%
92%
85%
80%
Answer: 99%
The predictive value negative (PVN) is 99%.
The trick with this kind of question is to pick an imaginary number of animals that you test, like 1000, and fill out your 2x2 table from there.
Follow the links to see diagrams step by step.
If prev is 10% then there must be 100/1000 dogs with heartworm and 900 dogs that are disease-free.
A 96% sensitive test will correctly call 96/100 positive (box “a”), and IN-correctly call 4/100 negative, (box “c”; these are the false negs).
If 100/1000 animals are infected, then 900/1000 are disease-free.
Your 98% specific test will correctly call 882/900 disease-free (box “d”: 0.98 X 900=882) and IN-correctly call 18/900 positive, (box “b”: these are the false pos).
Now your a,b,c, d boxes are all filled, it is easy to calculate PVN=d/ (c+d=882/882+4)=99%
A two-year-old range cow from a herd in Idaho is presented with beginning signs of high mountain disease (brisket edema, dyspnea).
The owner knows it’s important to bring the cow down below 6000 feet in altitude and to avoid locoweed in high pastures.
What else should the owner be told about this condition?
Stop herd access to Ponderosa pines
Don’t breed this cow
There’s no way to prevent this
Clear pasture of lupines
Prognosis for recovery is excellent if just move to lower altitude
Answer: Don’t breed this cow
Avoid breeding animals affected with high mountain disease (due to genetic component) and try to avoid pastures with locoweed in mountains over 6000 feet.
Do not return animals that have been affected to high altitudes - it will recur.
The prognosis is guarded to poor once signs of cardiac failure have begun.
Animals should be moved to lower altitudes with minimal stressors.
The single most useful treatment is thoracocentesis and drainage of pleural effusion.
Prevention is preferable: use genetic screening via measurement of pulmonary arterial pressure (PAP) to choose cattle resistant to the effects of hypoxia. This is mostly performed on breeding bulls and valuable cows.
Ponderosa pines are associated more with abortion. Lupine toxicosis in cattle affects either the nervous or hepatic systems.
Follow this link to a Merck table with images of toxic range plants.
Soon after introducing an adult male llama into a new pen with a prize female, the female llama is found down, in sternal recumbency. What is occurring?
Obturator paralysis
Aggression display
Female is in heat
Submission display
Back injury
Answer: Female is in heat
If a female llama or alpaca is in heat and receptive, the animal will usually assume a position of sternal recumbency (called “cush” or
“kush”) within seconds to minutes after introduction of a male and allow the male to breed. After intromission, the male llama often vocalizes, making a sound called “orgling.”
Reproduction of Llamas and Alpacas - Comprehensive Study Guide
Definitions and Reproductive Physiology
• Female Reproductive Anatomy: Small nonpregnant reproductive tract, short uterine horns, cervix with cartilaginous rings, and a suburethral diverticulum. • Male Reproductive Anatomy: Small testicles relative to body size, prepuce pointing backward, and a urethral diverticulum.
Physiology
• Females: Induced ovulators, seasonal breeders. Puberty at 10–12 months; first breeding typically at >24 months. Ovulation occurs 24–30 hours post-mating, with implantation around 30 days of gestation. Pregnancy mainly occurs in the left uterine horn. • Males: Androgen production begins before 8 months. Breeding age is 18-24 months. Ejaculate volume is small (2-5 mL).
Mating and Pregnancy
• Mating Behavior: Females assume a sternal recumbency when receptive. Males vocalize and ejaculate directly into the uterus. • Pregnancy Diagnosis: Based on progesterone levels, rectal palpation, and ultrasonography. Normal gestation is around 342 days.
Birth and Postpartum
• Stages of Labor: • Stage I: Lasts 1-6 hours, with increased urination and humming. • Stage II: Rapid delivery within 30 minutes. • Stage III: Placenta passage within 4-6 hours. • Postpartum: Females can conceive 14-21 days post-delivery.
Management of Reproductive Problems
• Issues: Fertility problems can arise from anatomical anomalies, infections, and dystocia. Proper diagnosis involves ultrasonography and hormonal treatments like hCG or GnRH for cervix relaxation.
A new AGID test kit for caprine arthritis and encephalitis (CAE) is being tested. Here are simulated test results, compared to a gold standard virus isolation test for CAE.
CAE pos CAE neg Total AGID positive 32 58 90 AGID negative 23 887 910 Total 55 945 1000
What is the predictive value positive of the new AGID test for CAE?
32/55
55/945
32/90
55/1000
90/1000
Answer 32/90
Predictive value positive (PVP) = 32/90 = a/(a+b) (36%, not great).
PVP is a way to state how much confidence you have in a positive result from the AGID.
It means “Of the goats my AGID says are positive (90), how many are truly positive? (only 32)”
Click here to see a Basic 2X2 table.
Caprine arthritis and encephalitis (CAE) is caused by a lentivirus in the Retrovirus family. Presentations vary. Most commonly, it is a subclinical disease of dairy goats, leading to production losses.
In adults with clinical disease, see a polyarthritis. Less commonly, see a progressive paresis in kids (leukoencephalomyelitis). Other presentations (not as common) include interstitial pneumonia, indurative mastitis (“hard udder”), and chronic wasting.
A skin scrape from a cow with pruritus and crusts around the caudal thighs and perineum shows the organism below.
What is the presumptive diagnosis?
Psoroptic mange
Chorioptic mange
Cutaneous onchocerciasis
Trombiculidiasis
Sarcoptic mange
Answer: Chorioptic mange
A winter presentation in the northeastern U.S. of crusty, pruritic skin disease around the perineum, caudal upper thigh is most likely to be chorioptic mange. Also called “leg mange.”
Rx: pour-on doramectrin or moxidectin, eprinometrin (injectible or pour-on), or lime-sulfur dips a 12 d.
On skin scrape, look for long legs and short UNsegmented pedicles with Chorioptes. In CONTRAST to the short legs and long UNsegmented pedicles of Sarcoptes.
Chorioptic Mange in Cattle - Comprehensive Study Guide
Definition
• Chorioptic Mange (Leg Mange, Foot and Tail Mange, Symbiotic Mange, Barn Itch): Caused by infestation with Chorioptes bovis or C. texanus.
Causative Agents
• Mites: Chorioptes bovis and C. texanus.
Pathophysiology
• Mechanism: Mites live on the skin surface, feeding on skin debris and causing irritation. They do not burrow. • Transmission: Direct contact and fomites; mites can survive off the host for up to 3 weeks.
Symptoms
• Clinical Signs: Nodules, papules, crusts, and ulcers. Lesions typically start at the pastern and can spread to the udder, scrotum, tail, and perineum. Mild pruritus, flaky dermatitis, self-trauma, and alopecia are common. • Seasonal: Lesions and clinical signs appear in late winter and spontaneously regress during summer months.
Diagnosis
• Methods: Clinical signs, microscopic examination of skin scrapings.
Treatment
• Medications: • Pour-on Doramectin • Eprinomectin (pour-on and injectable) • Moxidectin (pour-on) • Hot Lime Sulfur Dips or Sprays: Follow species-specific dilution and repeat at 12-day intervals if needed.
Which reportable disease has an identical clinical presentation. to foot and mouth disease (FMD)?
Bluetongue
Bovine viral diarrhea (BVD)
Bovine papular stomatitis
Vesicular stomatitis
Rinderpest
Answer: Vesicular stomatitis
Vesicular stomatitis (VS) can occur in epidemics and appears clinically identical to foot and mouth disease (FMD).
Can see VS in HORSES, pigs, cows. FMD is mainly in pigs and cows (NOT horses!!).
VS DOES occur in the U.S. and it is one of the big rule-outs among vesicular diseases (remember the big 8: BVD, IBR, BPS, MCF, bluetongue, VS, FMD, rinderpest).
In 2011, the United Nations Food and Agriculture Organization (FAO) and the World Organisation for Animal Health (OIE) officially declared that rinderpest was eradicated globally. But because it is a classic, severe, reportable, stomatitis-type disease, it’s unlikely that vets will be allowed to forget rinderpest on DDXs for years.
Vesicular Stomatitis in Cattle - Comprehensive Study Guide
Definition
• Vesicular Stomatitis (VS): A viral disease causing vesicular lesions on the mucous membranes and skin, primarily affecting horses, cattle, and sometimes pigs.
Causative Agents
• Viruses: Vesicular stomatitis virus serotypes New Jersey and Indiana, from the family Rhabdoviridae.
Pathophysiology
• Transmission: Direct contact with infected animals or via biting insects like black flies, sand flies, and midges. The virus infects mucosal surfaces, causing vesicles that rupture into ulcers.
Symptoms
• Clinical Signs: Fever, ptyalism (excessive salivation), vesicles, ulcers, erosions on the lips, tongue, teats, and coronary bands. Lesions can lead to secondary bacterial infections, mastitis in dairy cows, and lameness.
Diagnosis
• Methods: Clinical signs, serologic tests (competitive ELISA, virus neutralization, complement fixation), PCR assays, and viral isolation from lesions.
Treatment and Control
• Supportive Care: Softened feeds, antiseptic cleaning of lesions, and isolation of affected animals. • Prevention: Limit exposure to biting insects, maintain good hygiene, and report cases to animal health authorities. There are no commercially available vaccines in the US.
Zoonotic Risk
• Human Infection: Flu-like symptoms (fever, headache, myalgia), occasionally vesicles in the mouth and pharynx.
An adult Tennessee Walker gelding is presented for evaluation.
The hooves are pictured below.
The horse stands with the forelimbs stretched out and the hindlimb tucked underneath.
When asked to trot, the horse has an exaggerated leg motion, lifting the forelimbs high off the ground with each step.
The hair on the lower aspect of the forelimbs is curly and the horse is extremely sensitive to palpation of the dorsal pasterns.
What is the name of the illegal practice that has led to this horse?s presentation?
Docking or blocking
Alcohol blocking
Nicking or cutting
Velveting
Soring
Answer: Soring
This presentation is consistent with soring, which is an unethical and illegal practice of intentionally causing pain to exaggerate the leg motion of horses. The outcome is a chest-high stride called the
“big lick,” which unfortunately is desired in many competitions of gaited horses (esp. Tennessee Walkers).
Soring is achieved by application of chemical irritants to the lower limb, +/- use of “action devices” that make the horse pick up the leg faster, or mechanical/physical measures that make the feet incredibly sore.
The special shoes seen on this horse are called “stacks” - and they make the foot heavy to exaggerate the movement; unfortunately they can also hide application of items that cause pain/pressure on the bottom of the hoof.
The Horse Protection Act (HPA) of 1970 made soring illegal. The USDA enforces the HPA by having Designated Qualified Persons and/or Veterinary Medical Officers inspect horses at events. Any suspect cases should be reported to the USDA.
The American Association of Equine Practitioners (AAEP) and American Veterinary Medical Association (AVMA) support a ban on the use of action devices and performance packages in the training and showing of Tennessee Walking Horses.
Docking, blocking, nicking or cutting are are methods of tail alteration in horses, condemned by the AAEP. Alcohol nerve blocks are not illegal per se, but they tend to be long-term.
Velveting refers to the amputation of live growing antlers from cervids. The AVMA says that if velveting occurs, it must be conducted humanely, and within the bounds of a veterinarian-client-patient relationship.
Refs: The AVMA’s Policy Resources and the AAEP’s Policy on Soring. Image courtesy of Todd Behre, USDA APHIS.
The primary route of infection with Brucella abortus is:
Inhalation
Artificial insemination
Venereal (natural breeding)
Ingestion
Answer: Ingestion
Brucella abortus is primarily transmitted through INGESTION of contaminated milk, food and water, and via licking of genitals and contaminated uterine secretions.
Refs: The Merck Veterinary Manual online edition.
A two-year-old range cow from a herd in Idaho is presented with beginning signs of high mountain disease (brisket edema, dyspnea).
The owner knows it’s important to bring the cow down below 6000 feet in altitude and to avoid locoweed in high pastures.
What else should the owner be told about this condition?
Clear pasture of lupines
Prognosis for recovery is excellent if just move to lower altitude
There’s no way to prevent this
Don’t breed this cow
Stop herd access to Ponderosa pines
Answer: Don’t breed this cow
Avoid breeding animals affected with high mountain disease (due to genetic component) and try to avoid pastures with locoweed in mountains over 6000 feet.
Do not return animals that have been affected to high altitudes - it will recur.
The prognosis is guarded to poor once signs of cardiac failure have begun.
Animals should be moved to lower altitudes with minimal stressors.
The single most useful treatment is thoracocentesis and drainage of pleural effusion.
Prevention is preferable: use genetic screening via measurement of pulmonary arterial pressure (PAP) to choose cattle resistant to the effects of hypoxia. This is mostly performed on breeding bulls and valuable cows.
Ponderosa pines are associated more with abortion. Lupine toxicosis in cattle affects either the nervous or hepatic systems.
Bovine High-Mountain Disease (BHMD) - Comprehensive Study Guide
Definition
• Bovine High-Mountain Disease (Brisket Disease): A condition causing pulmonary hypertension and right ventricular heart failure in cattle at high altitudes.
Causative Agents
• Primary Cause: Hypoxia-induced pulmonary arterial vasoconstriction and hypertension. • Contributing Factors: Genetic predisposition, locoweed toxicity (swainsonine), and respiratory infections.
Pathophysiology
• Mechanism: Hypoxia at high altitudes causes pulmonary vasoconstriction and arterial hyperplasia, leading to pulmonary hypertension, right ventricular hypertrophy, and eventual heart failure. • Genetic Factors: High heritability; some cattle breeds and individuals are more susceptible.
Symptoms
• Clinical Signs: Brisket edema, jugular distension and pulsation, pleural effusion, ascites, depression, reluctance to move, labored breathing, cyanosis, and possible sudden death.
Diagnosis
• Methods: Clinical signs, elevated pulmonary arterial pressure (PAP) >50 mmHg, thoracic auscultation, and ruling out other causes of heart failure.
Treatment and Control
• Immediate: Move affected cattle to lower altitudes, supportive care (diuretics, antibiotics, thoracocentesis). • Prevention: Genetic selection for resistance, minimizing exposure to locoweed, and proper management of concurrent diseases.
Medications
• Supportive Care: Diuretics for edema, antibiotics for secondary infections, and appetite stimulators like vitamin B complex.
A 7-year-old female spayed DSH cat is presented with lacerations and bite wounds on her extremities. The owner saw a raccoon attack her cat in broad daylight.
This patient was seen 4 weeks ago when she received her annual booster shot for rabies.
What are the correct actions to take?
Booster on days 1, 3, 7; confine at home; 60 days observation
Immediate booster; confine at clinic; 10 days observation
Keep under owner control 45 days; booster on 46th day
Immediate booster; observe for 60 days; confine at home
Immediate booster; keep under owner control; observe 45 days
Answer; Immediate booster; keep under owner control observe 45 days
Immediate booster; Keep under owner control; Observe 45 days .
This cat is CURRENTLY vaccinated (remember: any rabies booster is considered IMMEDIATELY effective because of rapid anamnestic response).
According to the 2016 Compendium for Rabies Control, Dogs, cats, and ferrets that are currently vaccinated should be revaccinated immediately, kept under the owner’s control, and observed for 45 days.
Any illness in an isolated or confined animal should be reported immediately to the local health department. If signs suggestive of rabies develop, the animal should be euthanized and the head shipped for testing.
In general, both Canadian and U.S. guidance on rabies post exposure management conforms with Compendium guidelines.
Guidelines:
United States guidelines
2016 Compendium for Rabies Prevention and Control, JAVMA, Vol
248, No. 5., 505-517, courtesy, Natl. Assoc. State Public Health Veterinarians (NASPHV compendia).
For information on post-exposure prophylaxis in people see:
Human Rabies Prevention-US, 2008 ACIP Reccs: May 23, 2008 / 57(RRO3); 1-26,28.
Canadian guidelines
Canadian Food Inspection Agency (CFIA) rabies home page and rabies testing summary.
The Canadian Veterinary Medical Association (CVMA) on rabies guidance homepage.
Click here for a CVMA post-exposure management summary.
Click here for CVMA post-exposure management presentation.
Global guidelines WHO OlE World Health Organization Expert Consultation on Rabies (2nd Report, 2013).
A two-year-old Angus cow is presented with weakness of the hind limbs and a staggering gait.
On physical exam, the heart rate and respiratory rate are slow and irregular, and the pupils are dilated.
The cow’s breath and urine smell like the odor of mouse urine.
Suddenly the cow’s pulse becomes rapid and thready, she collapses, and dies of apparent respiratory failure.
Which one of the following plants is most likely to have caused this spectrum of clinical signs?
Tetradymia spp (Horsebrush)
Centaurea spp (Knapweed, Yellow star thistle)
Veratrum spp (False hellebore, Skunk cabbage)
Pinus ponderosa (Western yellow pine)
Conium maculatum (Poison hemlock)
Answer: Conium maculatum (Poison hemlock)
Poisoning with Conium maculatum (Poison hemlock) is responsible for the death of this cow.
At least eight toxic piperidine alkaloids have been isolated from poison hemlock.
Coniine is found in seeds and the mature plants; g-coniceine is found in young growing plants.
Poison hemlock is toxic to all livestock and humans. Signs of toxicity develop one to two hours after ingestion and are usually fatal.
Signs include nervousness, trembling, weakness especially of the hind limbs, weak pulse, irregular heart rate, recumbency, coma and death.
A mousy odor exuding from the urine and breath is pathognomonic.
Ingestion of poison hemlock during gestation causes arthrogryposis and other congenital defects in cattle, goats, and pigs.
A three-year-old female spayed domestic longhair cat is presented with hypersalivation, vomiting, diarrhea, tremors, ataxia, and a temperature of 105.2°F (40.7°C) [N=100-102.5°F (37.8-39.2°C)] Her pupils are normal size and responsive to light. The cat has a seizure while being examined.
The owner relates that he had treated her the night before with a flea dip originally bought for his dog.
What toxic ingredient most likely caused these signs?
Methylxanthine
Organophosphate
Carbamate
D-Limonene
Permethrin
Answer: Permethrin
Permethrin is a pyrethin common in topical flea and tick products. Pyrethrin toxicity in cats is relatively common occurrence after being treated with a concentrated pyrethrin-
containing flea product labeled for dogs.
RX: Methocarbamol (Robaxin®), a centrally-acting muscle relaxant, and (if needed) seizure control (e.g., diazepam). Unlike OPP/carbamate toxicities, do not treat permethrin toxicity with atropine.
Big DDXs are organophosphate (OPP) toxicity and carbamate toxicity which look similar. With OPP and carbamates, may see miosis, unlike permethrin/pyrethroid toxicity.
D-Limonene is a citrus-based anti-flea med that can cause vomiting in dogs.
Permethrin Toxicity in Cats - Comprehensive Study Guide
Definition
• Permethrin Toxicity: A type of pyrethroid poisoning, highly toxic to cats due to their inability to metabolize permethrin efficiently.
Causative Agents
• Permethrin: A synthetic pyrethroid commonly found in insecticides.
Pathophysiology
• Mechanism: Permethrin interferes with sodium channels in nerve cells, leading to prolonged depolarization and nerve hyperexcitability. • Metabolism: Cats lack glucuronidase enzymes, slowing the detoxification process and increasing toxicity.
Symptoms
• Clinical Signs: Hyperexcitability, tremors, seizures, hypersalivation, vomiting, dyspnea, weakness, and ataxia.
Diagnosis
• Methods: History of exposure, clinical signs, and detection of permethrin in body tissues.
Treatment
• Supportive Care: Bathe with mild detergent, control seizures with diazepam or methocarbamol, provide IV fluids, and administer activated charcoal. • Medications: Atropine sulfate for salivation control, methocarbamol for muscle tremors, phenobarbital for prolonged seizures.
This cow is off-feed, icteric and has raw irritated skin over the back, suggesting secondary photosensitization.
What is the underlying toxic agent that typically causes secondary photosensitization?
Gossypol
Aflatoxin
Ptaquiloside
Unconjugated bile acid
Phylloerythrin
Answer: Phylloerythrin
Secondary photosensitization is caused by plant-related hepatic damage, which releases photodynamic substances like phylloerythrin, a breakdown of product chlorophyll.
Failure to excrete phylloerythin due to liver dysfunction or bile duct lesions can lead to a build up in the blood and skin, where phylloerythin can absorb and release light energy,
causing phototoxicity.
Pyrrolizidine alkaloids are one cause of secondary photosensitization due to liver damage.
The plants most often implicated include ragwort (Senecio jacobea), woolly groundsel (Senecio redellii, Senecio longilobus), rattleweed (Crotalaria retusa), and seeds of yellow tarweed (Amsinckia intermedia).
Click here for a nice visual review of bovine skin conditions, courtesy of the Natl. Animal Disease Information Service (UK).
Overview of Photosensitization in Animals - Comprehensive Study Guide
Definition
• Photosensitization: Skin condition caused by interaction of photoactive substances with UV light, producing free radicals and reactive oxygen species leading to skin damage.
Types and Causes
1. Primary Photosensitization (Type I): Caused by ingestion or absorption of photodynamic agents like hypericin from St. John’s wort. 2. Aberrant Pigment Metabolism (Type II): Due to defective heme synthesis enzymes, leading to porphyrin accumulation. 3. Secondary (Hepatogenous) Photosensitization (Type III): Most common, due to impaired hepatic excretion of phylloerythrin, a chlorophyll by-product. 4. Idiopathic Photosensitization (Type IV): Unknown cause or unidentified photodynamic agent.
Pathophysiology
• Mechanism: UV light activates photodynamic agents, forming high-energy molecules that damage skin cells, leading to increased membrane permeability, cellular leakage, and enzyme release causing skin ulceration, necrosis, and edema.
Symptoms
• Clinical Signs: Photophobia, erythema, edema, vesicles, ulcers, necrosis, especially in non-pigmented skin areas.
Diagnosis
• Methods: Based on clinical signs, history, and detection of photodynamic agents or liver dysfunction. Elevated porphyrin levels in blood, urine, or feces confirm diagnosis.
Treatment
• Supportive Care: Shading, housing, corticosteroids for early stages, wound management, and preventing fly strike. Prognosis depends on the type, with primary photosensitization having a better outcome.
Fumonisin intoxication is primarily associated with neurologic disease in horses causing leukoencephalomalaci
What body system is primarily affected and what clinical signs occur in pigs with fumonisin toxicosis?
Reproductive; Estrogenism, vulvovaginitis
Circulatory/vascular; Terminal necrosis of extremities, gangrene
Respiratory; Pulmonary edema, death
Systemic; Vomiting, immunosuppression
Gastrointestinal; Salivation, retching
Answer: Respiratory, Pulmonary edema,death
Look for respiratory disease, with hypertension and pulmonary edema in pigs with fumonisin toxicosis. Porcine pulmonary edema (PPE) is usually acute and fatal. PPE appears to be caused by pulmonary hypertension with transudation of fluids into thorax, which leads to interstitial pulmonary edema and hydrothorax. Fumonisin is a Fusarium spp.
mycotoxin associated with moldy corn.
Think of reproductive dysfunction (estrogenism, vulvovaginitis) with zearalenone, the only known mycotoxin with primarily estrogenic effects.
Slaframine toxicosis causes profuse salivation, primarily in horses and occasionally in cattle. Due to the fungus Rhizoctonia leguminocola (black patch disease) on red clover
(Trifolium pratense) especially in wet, cool years.
Trichothecenes are a group of related cytotoxic mycotoxins associated with many fungi. Think of vomitoxin (and vomiting) and also of immunosuppression. Refusal to eat contaminated feed is a typical sign, due to taste aversion.
Macrocyclic trichothecene-related diseases have several specific names, including the best known, stachybotryotoxicosis.
Which of the following most correctly describes physiologic pain?
Pain that results when homeostasis is disturbed, as when dehydration is present
Pain that originates from damage to peripheral nerves or the central nervous system
A protective response to an actual or potentially damaging insult
The sensation that results when electrolytes or other biochemical compounds are imbalanced
Pain caused by stretching, tension, or inflammation of viscera
Answer: A protective response to an actual or potentially damaging insult
Physiologic pain is a protective response to an actual or potentially damaging insult. Basically, this is a normal healthy pain response - an automatic mechanism to avoid or minimize injury, which initiates the physiologic and physical response to pain.
Physiologic pain is also called nociceptive pain, as it involves the basic physiologic mechanisms of reception, transmission, and processing of stimuli that lead to perception of pain. Response to physiologic pain is behavioral, emotional, and physiologic; and both involuntary and voluntary.
Classic example - when a hand touches something hot, it unconsciously withdraws, moves away, and the heart rate increases, etc.
Withdrawal and tachycardia are involuntary responses that occur almost immediately. The next event is behavioral and voluntary, where one moves away, runs cold water on the burn, and changes how to handle the hot item, etc. The emotional component is when the person exclaims “OUC!.”
Stretching, tension, or inflammation of viscera causes visceral pain (e.g… colic in horses). Neuropathic pain is caused by damage to neural tissue.
What is the anatomic pathophysiology of founder in horses?
Chronic degeneration of the navicular bursa and bone
Failure of attachment between sensitive and horny laminae of hoof
Avulsion or periostitis of the third phalanx (PIII) extensor process
Thickening or bowing of the plantar tarsal ligament
Tarsal sheath distention of deep digital flexor
(DDF) tendon proximal to tarsus
Answer: Failure of attachment between sensitive and horny laminae of hoof
Founder, more properly known as laminitis, is characterized by failure of the attachment between the sensitive (dermal) and horny (epidermal or insensitive) laminae of the foot. These laminae are the “Velcro®”-like suspensory apparatus of the hoof that hold the third phalanx inside the hoof capsule and carry the weight of the entire horse.
Loss of the suspension mechanism of the third phalanx in the face of ongoing weight-bearing can result in rotation of the third phalanx within the hoof wall and/or ventral sinking of the third phalanx through the sole in severe cases.
There are 3 main etiologies of laminitis:
1) Systemic-inflammtory response syndrome (SIRS)-associated:
Laminitis is a common sequela to systemic inflammatory disturbances involving endotoxemia and elaboration of inflammatory mediators, including colonic torsion, grain overload, enterocolitis, pleuropneumonia, and metritis.
2) Endocrinopathic: Horses with insulin dysregulation and equine metabolic syndrome or pituitary pars intermedia dysfunction (PPID)
are at risk of laminitis. Events that can set off a case include grazing lush pasture, corticosteroid administration, and stress/ illness.
3) Support limb: Support limb laminitis in one hoof can occur when the limb is excessively loaded after to injury on the contralateral limb.
(A fourth, less common cause, is traumatic or “road founder.”)
Thickening or bowing of the plantar tarsal ligament is curb.
Distention of the tarsal sheath of the DDF tendon proximal to the tarsus is thoroughpin.
Avulsion/periostitis of the extensor process of PIll is called pyramidal disease.
Navicular disease is chronic degeneration of the navicular bursa and bone.
What is the anatomic pathophysiology of founder in horses?
Chronic degeneration of the navicular bursa and bone
Failure of attachment between sensitive and horny laminae of hoof
Avulsion or periostitis of the third phalanx (PIII) extensor process
Thickening or bowing of the plantar tarsal ligament
Tarsal sheath distention of deep digital flexor
(DDF) tendon proximal to tarsus
Answer: Failure of attachment between sensitive and horny laminae of hoof
Founder, more properly known as laminitis, is characterized by failure of the attachment between the sensitive (dermal) and horny (epidermal or insensitive) laminae of the foot. These laminae are the “Velcro®”-like suspensory apparatus of the hoof that hold the third phalanx inside the hoof capsule and carry the weight of the entire horse.
Loss of the suspension mechanism of the third phalanx in the face of ongoing weight-bearing can result in rotation of the third phalanx within the hoof wall and/or ventral sinking of the third phalanx through the sole in severe cases.
There are 3 main etiologies of laminitis:
1) Systemic-inflammtory response syndrome (SIRS)-associated:
Laminitis is a common sequela to systemic inflammatory disturbances involving endotoxemia and elaboration of inflammatory mediators, including colonic torsion, grain overload, enterocolitis, pleuropneumonia, and metritis.
2) Endocrinopathic: Horses with insulin dysregulation and equine metabolic syndrome or pituitary pars intermedia dysfunction (PPID)
are at risk of laminitis. Events that can set off a case include grazing lush pasture, corticosteroid administration, and stress/ illness.
3) Support limb: Support limb laminitis in one hoof can occur when the limb is excessively loaded after to injury on the contralateral limb.
(A fourth, less common cause, is traumatic or “road founder.”)
Thickening or bowing of the plantar tarsal ligament is curb.
Distention of the tarsal sheath of the DDF tendon proximal to the tarsus is thoroughpin.
Avulsion/periostitis of the extensor process of PIll is called pyramidal disease.
Navicular disease is chronic degeneration of the navicular bursa and bone.
In horses and ruminants, what lies between the sternocephalicus and brachiocephalicus muscles?
Jugular groove
Esophagus
Hyoid apparatus
Guttural pouch
External inguinal ring
Answer: Jugular groove
The jugular grooves lies between the sternocephalicus and brachiocephalicus muscles in ruminants and horses.
In horses, the omohyoideus muscle lies deep to the jugular vein in the cranial part of the neck whereas it is the sternomastoid muscle in ruminants. These muscles are clinically relevant because they make it safer to perform jugular venipuncture in the cranial one-third of the neck.
In this region they decrease the risk of inadvertent carotid artery puncture. Accidental administration of medications into the carotid artery can be dangerous, or even fatal.
A six-month-old Quarter horse colt is presented with an abnormal right forelimb, characterized by a steep dorsal hoof wall angle and a relatively short toe (i.e., a club foot).
What causes club foot, anatomically?
Congenital hyperextension of the metacarpophalangeal joint
Heel pain resulting from osteochondritis dissecans
Contractural deformity of the distal interphalangeal joint
Flaccidity of the flexor muscles
Rupture of the common digital extensor tendon
Answer: Contractural deformity of the distal interphalangeal joint
A club foot is caused by a contractural deformity of the distal interphalangeal joint, leading to a steep hoof wall angle and a relatively short toe, eventually leading to development of a boxy foot.
This can be a congenital deformity or an acquired deformity as a consequence of chronic pain due to nutritional imbalance resulting in developmental orthopedic disease, trauma, infection, etc.
Osteochondritis dissecans lesions can lead to pain, thus resulting in an acquired deformity. However, this is not a result of heel pain.
Flaccidity of the flexor muscles leads to the digital hyperextension seen in newborn foals. This problem usually corrects in a few weeks as muscle tone increases.
Rupture of the common digital extensor tendon results in a swelling in the tendon sheath at the dorsolateral aspect of the carpus. Foals are over in the knee and knuckle at the metacarpophalangeal joint while walking and potentially even standing.
