BCSE 15 Days For Test Day Flashcards
Which one of the following choices best describes the use of Digital Imaging and Communication in Medicine (DICOM) in digital radiology?
A universal digital image format that allows sharing of images between clinics
A technique that transforms digital images into hard copies for storage purposes
A method of obtaining digital radiographs with less radiation exposure
A means of converting traditional x-ray film into digital images
A mechanism that prevents artifacts from occurring on digital images
Answer: A universal digital image format that allows sharing of images between clinics.
Digital Imaging and Communication in Medicine (DICOM) is a universal digital image format that allows sharing of electronic images with hospitals, specialists and other locations (teleradiology).
DICOM is the standard image format for medical image generation and storage.
DICOM allows storage of images from a variety of different modalities (e.g., digital and computed radiography, computed tomography (CT), MRI, ultrasonography, digital fluoroscopy).
The DICOM image file contains patient identification, date and time of the examination, and display formats.
Link: Radiography on Animals. Filmless Radiography for Diagnostic Imaging in Animals.
https://www.merckvetmanual.com/clinical-pathology-and-procedures/diagnostic-imaging/radiography-of-animals?redirectid=4195?ruleredirectid=30#v3298717
Filmless Radiography in Animals
Overview
Filmless radiography, also known as digital radiography, has become the standard in veterinary diagnostic imaging due to its numerous advantages over traditional film-based methods. Digital radiography eliminates the need for film, screens, and processing chemicals, and offers several significant benefits for veterinary practices.
Types of Digital Radiography
1. Computed Radiography (CR)
• Mechanism: Uses a semiconductor plate in a cassette, exposed in the same manner as traditional film, which is then read electronically by a special reader.
• Advantages: Portable cassettes, cost-effective compared to DR systems, high resolution, and suitable for multiple imaging locations.
• Disadvantages: Requires periodic replacement of plates due to wear, intermediate reading step can be cumbersome.
2. Direct Digital Radiography (DR)
• Mechanism: Utilizes a cesium iodide scintillator array to absorb x-rays, which are then detected by an array of photodiode/transistor elements to create a digital image.
• Advantages: Faster image acquisition (available within 30 seconds), no need for intermediate reading steps, reduced wear and tear, better suited for high-volume practices.
• Disadvantages: Higher initial cost, sensitivity to electronic interference and physical shock.
Abdominal ultrasound of a dachshund reveals bilaterally enlarged adrenal glands (an example of one of the images is shown below). What clinical signs would you expect to see in a dog with these findings?
Lethargy, tragic facial expression, tail alopecia
Pruritis, alopecia of lower back, cold intolerance
Polydipsia, seizures, watery diarrhea
Polyuria, pendulous abdomen, truncal alopecia
Gastroenteritis, bradycardia, exercise intolerance
Answer: Polyuria, pendulous abdomen, truncal alopecia.
This is likely to be pituitary hyperadrenocorticism (HAC). Signs might include polyuria, pendulous abdomen, truncal alopecia.
This dog might also have polydipsia, polyphagia, muscle weakness, and recurrent urinary tract infections.
Roughly 80%-85% of canine HAC cases are pituitary-expect bilateral enlargement greater than 8mm on ultrasound.
Roughly 15%-20% of canine HAC cases are adrenal-expect unilateral adrenal enlargement greater than 8mm, with possible atrophy in the contralateral gland.
You can also see unilateral adrenomegaly with an incidental, nonfunctional adrenal mass or due to pheochromocytoma. This disease is relatively rare and difficult to diagnose.
Signs are non-specific, but intermittent weakness and collapse are commonly reported in diagnosed case-patients
Tail alopecia, tragic facial expression, and lethargy are signs of hypothyroidism.
Refs: Cote, Clinical Veterinary Advisor-Dogs and Cats, 3rd ed. pp. 525-7. Image courtesy, Dr Kalumet.
Link: Cushing Syndrome
https://www.merckvetmanual.com/endocrine-system/the-adrenal-glands/cushing-syndrome-hyperadrenocorticism
Link: Pheochromocytomas
https://www.merckvetmanual.com/endocrine-system/neuroendocrine-tumors/pheochromocytomas
Link: Hypothyroidism in Animals
https://www.merckvetmanual.com/endocrine-system/the-thyroid-gland/hypothyroidism-in-animals
A five-year-old female spayed domestic shorthair cat is presented with a month-long history of anorexia and lethargy. On physical examination she is 5-7% dehydrated. Which one of the following choices is apparent form these thoracic radiographs?
Hypovolemia
Normal radiographs
Hypertrophic cardiomyopathy
Allergic pneumonitis
Heartworm diseases
Answer: Hypovolemia.
This cat has hypovolemia (secondary to hepatic lipidosis).
The heart is small and lifted off of the sternum. The pulmonary vasculature, aorta, and caudal vena cava are reduced in size.
The pulmonary structures appear within normal limits. Within the viewable abdomen the liver appears enlarged, extending past the costochondral arches.
When circulating blood volume is reduced through blood loss, dehydration, or shock, the cardiac and vascular structures in the thorax can appear on radiographs.
In this case, the heart is small, giving the appearance of lifting from the sternum. The heart often appears more angular and less rounded than usual. The reduced pulmonary circulation also makes the lungs appear more lucent.
In this case, hepatic lipidosis (causing the apparent hepatomegaly) was the primary disease with secondary dehydration.
Link: Feline Hepatic Lipidosis
https://www.merckvetmanual.com/digestive-system/hepatic-disease-in-small-animals/feline-hepatic-lipidosis
Link: Normal Feline Thoracic Radiographs
https://vetmed.illinois.edu/imaging_anatomy/feline/thorax/ex03/thor03-f%20.html
A draft horse is presented whose left forefoot radiograph looks like the image below. What is the diagnosis?
Sidebone
Low ringbone
Navicular syndrome
Osselets
High ringbone
Answer: Sidebone.
This is an example of sidebone, an ossification of the cartilages of the third phalanx seen most often in heavy working horses.
Navicular syndrome (also called caudal heel pain) involves the navicular bone (distal sesamoid) and looks like this on radiographs (note the lollipops).
Periostitis & osteoarthritis of the proximal or distal interphalangeal joints leading to exostoses is called ringbone (high or low). Usually brought on by faulty conformation, improper shoeing, repeated concussion on hard surfaces, trauma, and infection.
Osselets is ringbone (arthritis, periosteitis) around the metacarpal/metatarsal phalangeal joint (fetlock).
Image courtesy of Nora Grenager, VMD, DACVIM.
Link: Sidebone in Horses
https://www.merckvetmanual.com/musculoskeletal-system/lameness-in-horses/sidebone-in-horses
Link: Navicular Disease in Horses
https://www.merckvetmanual.com/musculoskeletal-system/lameness-in-horses/navicular-disease-in-horses
Link: Osteoarthritis of the Proximal Interphalangeal Joint in Horses
https://www.merckvetmanual.com/musculoskeletal-system/lameness-in-horses/osteoarthritis-of-the-proximal-interphalangeal-joint-in-horses
A twelve-year-old female spayed rottweiler is presented for an acute onset of difficulty breathing. For the past month the dog has been lethargic with decreased appetite and weight loss.
A lateral thoracic radiograph is shown below.
What is the most likely diagnosis?
Left-sided heart failure
Aspiration pneumonia
Pneumothorax
Lymphoma
Diaphragmatic hernia
Answer: Lymphoma
This dog has pleural effusion caused by intrathoracic lymphoma.
Note the soft tissue density in the ventral chest with rounded lung lobe margins and widened interlobar fissures consistent with pleural effusion. The cardiac silhouette is obscured.
Confirm the presence of effusion with thoracic focused assessment with sonography for triage, trauma, and tracking (TFAST).
Perform thoracocentesis for both diagnostic and therapeutic purposes. Submit fluid for analysis and cytology to potentially identify neoplastic cells. If fluid cytology does not reveal an etiology, consider further imaging of the chest such as thoracic ultrasound or CT scan.
CGPT: Comprehensive Summary on Lymphoma in Dogs
A guinea pig is presented with inappetence, oculonasal discharge, and dyspnea. The clients also have a pet rat, and a pair of rabbits, and these animals all have frequent contact with each other.
Which of the following agents is the most likely cause?
Staphylococcus aureus
Dromaius novaehollandiae
Hymenolepis diminuta
Clostridium difficile
Bordetella bronchiseptica
Answer: Bordetella bronchiseptica
Rabbits can be subclinical carriers of Bordetella bronchiseptica, which is highly_pathogenic in guinea pigs. Because of this cross-species pathogenicity, rabbits and guinea pigs should not be kept together as pets.
Hymenolepis diminuta is a dwarf tapeworm in gerbils. It is possibly zoonotic to humans.
CGPT: Comprehensive Summary on Guinea Pigs
CGPT: Comprehensive Summary on Gerbils
A two-week-old calf is presented for colic and hemorrhagic diarrhea. It is one of the fastest-growing calves in the pasture and was normal yesterday.
The calf has abdominal distention, cyanotic mucous membranes, an upper eyelid skin tent of five seconds, and eyeball recession of six mm. During the physical exam the calf collapses and shows signs of opisthotonus.
What is the most likely diagnosis?
Coccidiosis
Cryptosporidiosis
Enterotoxemia
Coronavirus
Salmonellosis
Answer: Enterotoxemia
Peracute colic, hemorrhagic diarrhea, and neurologic signs in a two-week-old fast growing calf is a classic presentation for enterotoxemia (Clostridium perfringens type C). The findings of cyanosis along with skin tent and eyeball recession indicate moderate to severe dehydration and cardiovascular compromise.
Treatment consists of fluid therapy, Clostridium perfringens type C antitoxin, and antimicrobials. Oral penicillin can be used in food animals. Oral metronidazole is recommended in horses but is prohibited for use in food animals in the U.S.
Prognosis is poor even with treatment so best to prevent through vaccination of dams and subsequent passive transfer of immunity to calves.
Colibacillosis is a possible cause of peracute diarrhea but is typically seen in very young calves less than five days of age.
In general, remember the AGE, SEVERITY, and # AFFECTED for calf diarrheas.
The EARLY diarrheas are due to:
Escherichia coll - less than 5d old, multiple cases Rotavirus - 5d-2 wks old, self limiting, multiple calves Coronavirus - 4-30d, multiple calves
Enterotoxemia - (Clostridium perfringens type C) 2 wks old, healthiest, fastest growing calf, hemorrhagic diarrhea, sudden death
Cryptosporidia -1-4 wks, diarrhea, tenesmus, emaciation
LATER diarrheas are:
Neonatal salmonella - 1-2 mos, fever and diarrhea, septicemia, sudden death
Coccidiosis - older than 21 days and in ALL ages, bloody diarrhea, tenesmus
CGPT: Enterotoxemias in Animals
CGPT: Diarrhea in Neonatal Ruminants
CGPT: Cryptosporidiosis in Animals
CGPT: Salmonellosis in Animals
CGPT: Coccidiosis of Cattle
A cow showing chronic cerebral neurologic signs is presented for euthanasia.
You submit the brain for histopathology. Microscopically the brain tissue appears vacuolated (see image below).
Which one of the following choices is the most likely diagnosis?
Malignant catarrhal fever
Rabies
Bovine spongiform encephalopathy
Actinomycosis
Haemophilus somnus thromboembolic meninogencephalitis
Answer: Bovine spongiform encephalopathy
These are the typical histopathology findings highly suggestive of bovine spongiform encephalopathy. (BSE). The misfolded proteins (prions) cause vacuolization (“spongiosis”) of the brain.
BSE causes variant Creutzfeldt-Jakob disease (vCJD) in humans
(ZOONOTIC) and a progressive, fatal, infectious neurologic disease of the central nervous system of cattle.
Contact the proper regulatory personnel (REPORTABLE) while the lab performs a confirmatory diagnostic test (e.g., immunohistochemistry, Western immunoblot).
A characteristic histopathologic appearance of rabies is the presence of intracytoplasmic inclusions known as Negri bodies.
CGPT: Bovine Spongiform Encephalopathy (BSE)
The best place to take a horse’s pulse is to place fingers over
which one of the following structures?
Vena Cava
Jugular vein
Facial artery
Carpus
Heart
Answer: Facial Artery.
The most convenient location for taking the pulse of a horse is to place two or three fingers over the facial artery, in the notch of the mandible (lower jaw) just in front of the masseter (cheek) muscle.
Click here to see a to see a video of a vet taking a horse’s pulse.
Click here to see a Table of normal heart-rates of different animals.
Table of normal respiration-rates of different animals.
Which one of the following choices can be added to the diet of sheep and goats to reduce the incidence of frothy bloat?
lonophores
Vitamin E
Antiparasitics
Sulfa antibiotics
Minerals
Answer: Ionophores
The inclusion of ionophores in the diet decreases the formation of free ruminal gas, which can then get trapped in a stable foam leading to frothy bloat.
Frothy bloat occurs when chloroplast proteins liberated by digestion coat gas bubbles produced normally by rumen microbes.
The bubbles become stabilized by the proteinaceous froth. The animal cannot eructate the froth, which leads to rumen tympany.
The froth also cannot pass through a needle or a stomach tube.
Frothy bloat usually occurs after the ingestion of a lot of legumes (e.g., clover, alfalfa), and/or ingestion of lush pasture. Slow introduction to these feedstuffs, providing supplementatal feed, and feeding poloxalene can also help prevent.
CGPT: Bloat in Ruminants
Pediculosis is correctly described by which one of the following choices?
Invasion of fly larvae
Colonization with protozoa
Infection of a dog’s paw
Infestation with lice
Answer: Infestation with lice
CGPT: Lice in Animals
Which one of the following choices is the best way to prevent o
grain overload?
Ensure adequate water supply
Transfaunate the rumen
Give penicillin when concentrates are increased
Introduce dietary changes slowly
Restrict movement and access to legume hay
Answer: Introduce dietary changes slowly.
Grain overload results when ruminants ingest too much feed with readily digestible carbohydrates at one time.
Excessive carbohydrate causes a shift to gram-positive organisms in the rumen, especially Streptococcus bovis, which proliferate excessively.
These organisms produce large amounts of acid which damage the rumen and are absorbed, causing acidosis, dehydration, ileus, and eventually cardiovascular collapse and death.
Transfaunation of the rumen fluid is helpful after grain overload is resolved to help restore the normal flora of the rumen.
CGPT: Grain Overload in Ruminants
According to current American Association of Feline Practitioners (AAFP) recommendations, which three vaccines should pet cats routinely receive in addition to rabies and feline leukemia vaccinations?
Intranasal feline herpesvirus, feline parvovirus,
pneumonitis
Panleukopenia, feline herpesvirus-1, calicivirus
Bordatella bronchiseptica, feline immunodeficiency virus, dermatophyte
Feline infectious peritonitis, dermatophyte, calicivirus
Feline viral rhinotracheitis, Mycoplasma felis,
Chlamydophilia felis
Answer: Panleukopenia, feline herpesvirus-1, calicivirus
The American Association of Feline Practitioners (AAFP) vaccination guidelines recommend three “core” vaccines for ALL cats, +/- other vaccines depending on the circumstances (i.e.: household pet, shelter).
The three core feline vaccines are:
1. Feline herpesvirus-1 ( FHV-1)
2. Feline panleukopenia (feline parvovirus, FPV)
3. Feline calicivirus (FCV)
The AAFP states that rabies is “essential in regions where required by statute/law,” and is required in most states in the US and Canada. So, cats should receive rabies vaccination in addition to the core three.
Other vaccines to consider, depending on circumstances:
- Feline leukemia virus (FeLV) vaccination is recommended for group-housed cats and is considered a core vaccine for pet cats <1
yo
- For shelters consider intranasal FHV-1 and FCV on admission for high-risk populations and kittens >4 wo. Provides more rapid protection.
Here are the 2020 AAFP feline vaccination guidelines.
https://journals.sagepub.com/doi/pdf/10.1177/1098612X20941784
CGPT: Feline Panleukopenia
CGPT: Feline Respiratory Disease Complex
CGPT: Feline Leukemia Virus (FeLV)
Which one of the following diseases/syndromes is NOT reportable?
Avian psittacosis (Chlamydia psittaci)
Johne’s disease
Pthiris pubis infestation
Any vesicular disease of livestock
Answer: Pthiris pubis infestation.
Although the presence of Pthiris pubis (Human pubic lice) on a pet may be alarming to the owner, human pubic lice are NOT reportable. Psittacosis IS reportable because it is infectious and a serious cause of zoonotic respiratory disease in birds and humans.
Johne’s disease IS reportable in cattle. Brucellosis IS REPORTABLE. Basically, ANY vesicular disease of livestock IS REPORTABLE.
There are a number of things you should do in the face of a vesicular disease outbreak,
but the most important is to report the incident to the state vet/federal authorities.
The most important rule out is Foot and Mouth disease, which is difficult to distinguish from Swine vesicular disease, Vesicular exanthema of swine, and Vesicular stomatitis.
Because FMD is NOT present in the US, suspicion of it in a domestic swine herd is cause for state/federal government concern because of the potential agro-economic consequences. DDX via blood tests, primarily PC and biopsy.
Refs: Merck Veterinary Manual online edition.
Link: Avian Chlamydiosis
https://www.merckvetmanual.com/poultry/avian-chlamydiosis/avian-chlamydiosis
Link: Paratuberculosis in Ruminants
https://www.merckvetmanual.com/digestive-system/intestinal-diseases-in-ruminants/paratuberculosis-in-ruminants?redirectid=3156?ruleredirectid=30
Link: Overview of Brucellosis in Large Animals
https://www.merckvetmanual.com/reproductive-system/brucellosis-in-large-animals/overview-of-brucellosis-in-large-animals
Link: Foot-and-Mouth disease in Animals
https://www.merckvetmanual.com/generalized-conditions/foot-and-mouth-disease/foot-and-mouth-disease-in-animals?autoredirectid=14225
Link: Swine Vesicular Disease
https://www.merckvetmanual.com/generalized-conditions/swine-vesicular-disease/swine-vesicular-disease?autoredirectid=16670
Link: Vesicular Exanthema of Swine
https://www.merckvetmanual.com/generalized-conditions/vesicular-exanthema-of-swine/vesicular-exanthema-of-swine?autoredirectid=14240
Link: Vesicular Stomatitis in Horses
https://www.merckvetmanual.com/horse-owners/disorders-affecting-multiple-body-systems-of-horses/vesicular-stomatitis-in-horses
Which of the following is the correct description of pre-emptive analgesia?
Use of an antagonist to reverse dangerous side effects of an analgesic medication
The combination of different types of analgesic medications and procedures to treat pain
Treatment with pain medication during surgery and prior to recovery of a patient
Administration of pan medication prior to elective surgery and stimulation of the pain response
Use of higher doses of pain medication given previously to a patient to achieve adequate analgesia
Answer: Administration of pain medication prior to elective surgery and stimulation of the pain response.
Administration of pain medication prior to elective surgery / stimulation of the pain response is preemptive analgesia. Giving analgesics before the pain starts is the best way to minimize the pain response in a healthy patient who is not painful prior to surgery.
Fewer complications and shorter hospital stays are seen when patients are comfortable following painful procedures.
Analgesic therapy should be continued perioperatively and postoperatively for a few days to weeks depending on the procedure. Dosing should be decreased gradually and then stopped.
Tolerance is seen when higher doses of pain medications are required. This occurs with opioids. Using combinations of different types of analgesic medications and procedures is multi- modal analgesia/anesthesia.
Better analgesia and sedation are usually seen with combination therapy; lower doses can often be utilized as synergistic effects are common.
Click here to see a good summary on pain management, courtesy of the American College of Veterinary Surgeons (ACVS).
https://www.acvs.org/small-animal/pain-management
Refs: Bassert, Beal and Samples, McCurnin’s Clinical Textbook for Veterinary Technicians, 9th ed., p. 988, Gaynor & Muir Handbook of Vet Pain Mgt 2nd ed. pp.57, 349, 482, Tranquilli, Grimm, & Lamont Pain Mgt for the SA Practitioner 2nd ed. p. 10 and Greene’s Vet Anes & Pain Management Secrets, pp. 331-3.
Link: Small Animal Health Topics
https://www.acvs.org/small-animal
For what condition is dogs is the parotid duct sometimes translocated to the lateral canthus of the eye?
Imperforate lacrimal puncta
Refractive glaucoma
Diabetes-associated cataracts
Cherry eye
Keratoconjunctivitis sicca
Answer: Keratoconjunctivitis sicca.
Parotid duct translocation is indicated for chronic, nonresponsive cases of keratoconjunctivitis sicca (KCS). The parotid gland then lubricates the eye with saliva.
KCS is due to aqueous tear deficiency in dogs (and less so, cats and horses). Causes in dogs: Autoimmune dacryoadenitis (most common), distemper, idiopathic (removal of nictitans), drug-induced (NSAIDs and sulfonamides), neurogenic, traumatic, or congenital.
Clinical signs: Persistent, painful mucopurulent conjunctivitis with corneal ulceration and scarring. Corneas look dull.
Medical Tx: Topical artificial tears and antibiotic-corticosteroid combinations (if no corneal ulceration); increase tear production with topical cyclosporine A, tacrolimus, or pimecrolimus. Can give enteral pilocarpine for neurogenic KCS and topical acetylcysteine to lyse excess mucus and allow other topical medications to spread.
Lifelong Tx typically necessary.
Click here to see images and read more on KCS from the American College of Veterinary Ophthalmology.
https://www.acvo.org/common-conditions-1/2018/2/2/dry-eye-keratoconjunctivitis-sicca
Refs: The American College of Veterinary Ophthalmology website, Côté, Clin. Vet. Advisor: Dogs and Cats, 3rd ed. pp. 577-8,.
Link: Nasolacrimal and Lacrimal Apparatus
https://www.merckvetmanual.com/eye-diseases-and-disorders/ophthalmology/nasolacrimal-and-lacrimal-apparatus?redirectid=27591
Which one of the following is true regarding bovine leukosis virus?
Most infected animals have no outward clinical signs
The mosto common consequence of infection is lymphosarcoma
Feces of infected cattle are a major source of transmission
Passage in milk has been linked to human adult T cell leukemia / lymphoma
Beef cattle are more frequently infected that dairy cattle
Answer: Most infected animals have no outward clinical signs.
The most common outcome of infection with Bovine leukosis virus (BLV) is persistent infection with no outward clinical signs or lymphocytosis.
About a 1/3 of infected cattle develop a persistent benign lymphocytosis and <5% develop lymphosarcoma.
BLV infection is more common in dairy cattle than in beef cattle.
BLV is not a zoonosis. There is no treatment.
Risk is minimized by preventing the transfer of blood (and therefore infected lymphocytes) between cattle. Vertical transmission can also occur.
Refs: The Merck Veterinary Manual online edition.
Link: Overview of Bovine Leukosis
https://www.merckvetmanual.com/generalized-conditions/bovine-leukosis/overview-of-bovine-leukosis
Bovine Leukosis: Comprehensive Information for BCSE Test
Definition
• Bovine Leukosis (Bovine Lymphosarcoma): A cancerous disease caused by Bovine Leukemia Virus (BLV), an oncogenic retrovirus.
Etiology and Transmission
• Causative Agent: Bovine Leukemia Virus (BLV), a C-type oncogenic retrovirus.
• Transmission: Primarily horizontal through blood transfer (e.g., contaminated needles, dehorning tools), and rarely vertical (transplacental or via colostrum).
Epidemiology
• Prevalence: High in US dairy herds (~46.5%) and lower in beef herds (~10.3%).
Pathogenesis
• Infection Outcomes:
• Asymptomatic: Most animals show no signs.
• Persistent Lymphocytosis: ~29% develop this benign condition.
• Lymphosarcoma: <5% develop cancerous tumors.
Clinical Findings
• Juvenile Lymphosarcoma: Weight loss, fever, dyspnea, bloat, and posterior paresis.
• Thymic Lymphosarcoma: Cervical swelling, dyspnea, bloat, jugular distention, tachycardia.
• Cutaneous Lymphosarcoma: Cutaneous plaques, enlarged lymph nodes.
Diagnosis
• Serology: ELISA and PCR for BLV detection.
• Cytology/Histology: Biopsy for diagnosing lymphosarcoma.
Treatment and Control
• No Treatment: No effective treatment; symptomatic care with corticosteroids.
• Control Measures: Testing and culling infected animals, disinfection of equipment, using single-use needles.
Prevention
• Blood Precautions: Avoiding exposure to blood from infected animals.
• Colostrum Management: Using colostrum from seronegative cows.
• Farm Practices: Cleaning equipment and facilities, controlling flies.
Zoonotic Risk
• Human Risk: Potential, but not well-established, zoonotic risk through ingestion of unpasteurized dairy products.
Which of the following opioids is more potent than morphine, given most often via continuous intravenous infusion, or can be administered via transdermal patch?
Fentanyl
Naloxone
Oxymorphone
Buprenorphine
Tramadol
Answer: Fentanyl.
Fentanyl is very lipophilic, so it is absorbed and eliminated quickly. It is therefore not useful for pain control via single doses given intramuscularly (IM) or intravenously (IV).
However, it produces good analgesia when given continuously via intravenous infusion and, in many patients, via a transdermal patch. Serum levels can be variable in some patients with patches.
Absorption is affected by temperature; the use of heating blankets can increase levels, hypothermia will decrease levels.
Fentanyl is less likely to cause nausea and vomiting compared to morphine and other mu-agonist opioids. It does cause respiratory depression and dysphoria in some patients.
Other analgesics that can be administered via transdermal patches are lidocaine and buprenorphine.
Use of patches in patients at home must be evaluated carefully - toxicity and death has been seen in children and small animals that have ingested fentanyl patches.
See very nice articles on pain management and opioids in small animals: Murrell J. Clinical use of opioids in dogs and cats: Part 1. Companion Animal 2011; 16(4): 35-8, and Part 2, 16(5): 44-9.
The American Animal Hospital Association (AHA) provides this chart on Opioids and their actions
https://www.aaha.org/aaha-guidelines/2020-aaha-anesthesia-and-monitoring-guidelines-for-dogs-and-cats/drug-combinations/opiods/
Refs: Bassert, Beal and Samples, McCurnin’s Clinical Textbook for Veterinary Technicians, 9th ed., p. 993, Gaynor & Muir Handbook of Vet Pain Mgt 2nd ed. pp. 118-9, 244-5, 169, 348, 422, Greene, Vet Anes & Pain Mgt Secrets pp. 78-9, 336-7.
Link: Analgesic Pharmacology
https://www.merckvetmanual.com/management-and-nutrition/pain-assessment-and-management/analgesic-pharmacology
Comprehensive Summary on Analgesics Used in Animals for BCSE Test Preparation
Opioids
• Mechanism: Bind to opioid receptors (mu, kappa, delta) altering pain perception.
• Examples:
• Morphine, Hydromorphone, Fentanyl: Strong mu agonists.
• Buprenorphine: Partial mu agonist.
• Butorphanol: Agonist-antagonist.
• Effects: Analgesia, sedation, euphoria, dysphoria, respiratory depression.
Nonsteroidal Anti-inflammatory Drugs (NSAIDs) and Corticosteroids
• NSAIDs:
• Mechanism: Inhibit COX enzymes, reducing prostaglandin synthesis.
• Examples: Meloxicam, Robenacoxib (cats), Carprofen, Deracoxib (dogs).
• Effects: Analgesia, anti-inflammatory, antipyretic.
• Corticosteroids:
• Mechanism: Inhibit phospholipase A2, reducing inflammation.
• Examples: Prednisone, Dexamethasone.
• Effects: Anti-inflammatory, immunosuppressive, analgesic.
Alpha2-Agonists
• Mechanism: Bind to alpha2-adrenergic receptors, providing analgesia and sedation.
• Examples: Xylazine, Dexmedetomidine.
• Effects: Sedation, analgesia, muscle relaxation.
• Risks: Bradycardia, hypotension, arrhythmias.
Ketamine
• Mechanism: NMDA receptor antagonist, preventing central sensitization.
• Effects: Somatic analgesia, poor visceral analgesia, prevents wind-up.
• Uses: As part of multimodal analgesia.
Other Analgesic Agents
• Tramadol:
• Mechanism: Weak mu agonist, inhibits serotonin and norepinephrine reuptake.
• Effects: Analgesia, anti-anxiety.
• Risks: Seizure threshold reduction.
• Gabapentin:
• Mechanism: Binds to alpha2-delta subunit of voltage-gated calcium channels.
• Uses: Neuropathic pain, chronic pain.
• Amantadine:
• Mechanism: NMDA receptor antagonist.
• Uses: Chronic pain, opioid tolerance.
• Acetaminophen:
• Mechanism: Unclear, possibly COX-3 inhibition.
• Uses: Breakthrough pain in dogs (not cats due to toxicity).
• Maropitant:
• Mechanism: NK-1 receptor antagonist.
• Uses: Anti-emetic, visceral analgesia.
• Monoclonal Antibodies:
• Examples: Frunevetmab (for osteoarthritis in cats).
• Mechanism: Target NGF, reducing pain.
Which part of a tooth is the occlusal surface?
Towards the roof of the mouth
Toward the cheek
Toward the tongue
Chewing surface
Above the gum line
Answer: Chewing surface.
The occlusal surface of the tooth is the chewing surface. The crown is the visible tooth above the gum line. Buccal means the surface toward the cheek. Lingual is the surface toward the tongue. Palatal is towards the roof of the mouth.
Refs: Bassert, Beal and Samples, McCurnin’s Clinical Textbook for Veterinary Technicians, 10th ed., p. 1118-20.
Which one of the following phrases is the correct explanation of polychromasia?
An abnormal white blood cell count
Changes in shape of the nuclei of red blood cells
An abnormal red blood cell count
Variable color intensity of red blood cells
The presence of parasites inside the red blood cells
Answer: An abnormal red blood cell count.
Polychromasia is present when the color of red blood cells on a blood smear varies, usually from increased numbers of cells with more or less color than usual.
The highly colored cells are immature RBCs released into circulation too early; the color is from cellular organelles that are still present.
A small amount of polychromasia is not abnormal but large numbers means that immature red blood cells are present in circulation.
In anemic animals, this indicates that a regenerative response is present. Polychromatic cells can be seen best on a smear stained with new methylene blue.
Click here to see an image of polychromasia at Cornell’s eClinPath website.
https://eclinpath.com/hematology/morphologic-features/red-blood-cells/color/
Refs: McCurnin and Basset’s, Clin Textbook for Vet Technicians, 9th ed. pp. 380.
A horse is presented in severe respiratory distress in southern California after a suspected rattlesnake bite. There is significant nasal swelling, flared nostrils, abdominal movement with each breath, stridor, and tachypnea.
The veterinarian is concerned about local tissue damage, upper airway obstruction, and coagulopathy.
In addition to routine CBC and a blood chemistry panel, what tests will be ordered to assess for coagulation problems?
Prothrombin time, partial thromboplastin time
Baseline cortisol levels
Refractometry to estimate plasma protein, including fibrinogen
Lipase and amylase assays
Serum amyloid A acute phase protein assay
Answer: Prothrombin time, partial thromboplastin time
A coagulation panel should be run, which generally includes these standard tests for coagulation: prothrombin time (PT), activated partial thromboplastin time (aPTT), and sometimes activated clotting time (ACT).
Coagulopathies are common in association with pit viper (crotalia; e.g., rattlesnake) envenomation. Additional concerns include thrombocytopenia, neurotoxicity, and cardiovascular toxicity.
In contrast, expect hemolysis, lower motor neuron paralysis, and mental depression with coral snake (Micrurus spp.) envenomation.
Clinical signs with pit viper envenomation typically develop rapidly (w/in 15 minutes), whereas onset of clinical signs with coral snake bites can be delayed up to 36 hours (though usually progress extremely rapidly (within minutes)).
A two-year-old female spayed great Dane dog is presented with a one-month history of focal alopecia, scaling, and crusting around the ears and face.
Cytology of a skin scraping is shown below.
What is the most effective systemic treatment?
Praziquantel
Lufenuron and milbemycin oxime
Amitraz and ivermectin
Amphotericin-B
Terbinafine
Answer: Terbinafine
Terbinafine is the drug of choice for canine dermatophytosis (ringworm). One treatment regimen is 30-40 mg/kg PO q 24h or week on/week off until cured.
Itraconazole is the drug of choice for cats, but may be cost-prohibitive in dogs. Amphotericin-B is a systemic antifungal, but is not used to treat ringworm.
Dermatophytosis is a fungal infection of keratinized tissue (skin, hair, and claws), usually caused by Microsporum canis in cats and dogs. The incidence of disease is higher in cats than dogs and it is most common in young animals.
Look for focal/multifocal, sometimes circular, regions of alopecia, scaling, and crusting with variable inflammation and pruritus.
Confirm Dx with fungal culture of hair and skin scale.
Tx can be local or systemic and is generally recommended to minimize spread and shorten the clinical course of disease.
Dermatophytosis is a zoonosis (so wash your hands or wear gloves)!
CGPT: Dermatophytosis in Dogs and Cats
In addition to daily insulin injections, which interventions are important for treatment of non-ketotic diabetes mellitus in dogs (and cats)?
Glipizide; restrict activity; urinary acidifiers
Antidiuretic hormone; Florinef®; fluid restriction
Glucotrol®; high calorie/low fiber diet; promote water consumption
Balanced diet; exercise; treat concurrent diseases
Omeprazole; low sodium/highly digestible diet;
free choice water
Answer: Balanced diet; exercise; treat concurrent diseases
Treat uncomplicated diabetes mellitus (DM) with insulin, a balanced diabetic-appropriate diet (typically fed q12h), exercise (decreases insulin requirement), and treatment of concurrent diseases.
Diet formulation depends on an animal’s body condition, species, and concurrent diseases. In dogs, consider a diet higher in complex carbohydrates (i.e., fiber). In cats, consider a low-simple carbohydrate diet.
Note - glipizide and Glucotrol® are the same oral hypoglycemic drug, no longer recommended for the treatment of DM in cats.
CGPT Comprehensive Summary on the Treatment of Diabetes Mellitus (DM) in Dogs and Cats
What does it mean if a cat has physiologic nystagmus?
Head shaking related to inner ear disturbance
Abnormally loud gastrointestinal sounds in the absence of a recent meal
Genital malformation
Loss of balance
Normal, rapid, involuntary movement of eyes as head moves side to side
Answer: Normal, rapid, involuntary movement of eyes as head moves side to side
Physiologic nystagmus is a normal, rapid, involuntary movement of both eyes that occurs when an animal’s head is moved from side to side.
You can see it easily if you try it on your own dog or cat. Click here to see a short demonstration video of nystagmus (human eye).
Nystagmus can also be abnormal due to disease processes that may cause nystagmus when the head is stationary, or make the eyes move in abnormal directions as the head moves.
Vestibular disease can be peripheral (e.g., otitis media and otitis interna or nasopharyngeal polyps) or central (e.g., FIP, toxoplasmosis, neoplasia).
CGPT: Comprehensive Summary on Feline Infectious Peritonitis (FIP)
CGPT: Comprehensive Summary on Toxoplasmosis in Animals
A mature goat presents with drooling, left-sided ptosis, a droopy left ear, and positional nystagmus. The goat is also febrile, lethargic, and circling to the left.
Which one of the following choices is the best treatment for the presumptive diagnosis?
Ponazuril (PO, 28 days), sulfadiazine with pyrimethamine
Thiamine (TID, IV 1st dose, then IM), dexamethasone and supportive care
Clarithromycin (PO, BID) and rifampin
High dose oxytetracycline or penicillin
Specific botulinum antitoxin, NSAIDs, and B-lactam antibiotics
Answer: High dose oxytetracycline or penicillin
Treat this likely case of listeriosis with high doses of tetracyclines or penicillin. Isolate the goat and take it off silage, +/- IV fluids.
Some of the signs are subtle in this image, but classically look for unilateral ipsilateral signs of brainstem and facial nerve dysfunction
-swelling of cheek due to accumulation of food in the buccal space, drooling, ptosis (lowered eyelid), drooping ear, collapsed nostril, flaccid lip.
Typically listeriosis presents as encephalitis (depressed, fever) with unilateral limb signs (circling, leaning) and unilateral cranial nerve signs as discussed above. Also can see sporadic ABORTIONS with listeriosis at any time in gestation, though more common in 3rd trimester.
Listeria is ZOONOTIC. Highest risk is handling aborted fetus or performing necropsy of septicemic animal.
With polioencephalomalacia, think opisthotonos, headpressing, blind, ‘star-gazing’ (dorso-medial strabismus via thiamine deficiency).
Caprine arthritis encephalitis (CAE) presents as a polyarthritis in adults, progressive paresis in kids.
Key Information on Listeriosis in Animals
Definitions
• Listeriosis: A bacterial infection caused by Listeria monocytogenes, leading to encephalitis, abortion, septicemia.
Causative Agent
• Organism: Listeria monocytogenes, a gram-positive, motile, nonspore-forming coccobacillus.
Epidemiology
• Reservoirs: Soil, GI tracts of mammals, silage.
• Transmission: Ingestion of contaminated feed, especially spoiled silage; fecal-oral route.
Clinical Findings
• Ruminants: Encephalitis, asymmetric brain-stem dysfunction (circling, head tilt, facial paralysis), abortion, septicemia.
• Other Animals: Septicemia in monogastric animals, abortion in all domestic animals.
Diagnosis
• Clinical Signs: Asymmetric neurologic signs, abortion without prior symptoms.
• Tests: CSF analysis (increased protein, mild pleocytosis), bacterial culture, PCR, immunofluorescence.
Treatment
• Antimicrobials: High doses of penicillin G, oxytetracycline, ceftiofur, erythromycin.
• Supportive Care: Fluids, electrolytes, corticosteroids.
Control and Prevention
• Silage Management: Avoid feeding spoiled silage, use acidic silage additives.
• Vaccination: Efficacy varies; not always recommended.
Zoonotic Risk
• Human Infection: Handling of contaminated materials; can cause severe illness in immunocompromised individuals.
CGPT: Comprehensive Summary on
Polioencephalomalacia (PEM) in Ruminants
CGPT: Comprehensive Summary on Caprine Arthritis and Encephalitis (CAE)
Which of the following choices is the correct description of guttural pouch tympany?
Viral infection of the guttural pouch
Bacterial infection of the guttural pouch
Air trapped in the guttural pouch
Fungal infection of the guttural pouch
Fracture of the stylohyoid bone within the guttural pouch
Answer: Air trapped in the guttural pouch
Guttural pouch tympany is trapping of air in the guttural pouch typically seen in foals. Look for a non-painful fluctuant swelling on one or both sides of the throat.
Guttural pouch empyema is a bacterial infection of the guttural pouch. It is most often seen with or following strangles infection.
Guttural pouch mycosis is a fungal infection of the guttural pouch.
Epistaxis is the most common clinical sign.
Fracture of the stylohyoid bone within the guttural pouch can be part of a disorder called temporohyoid osteoarthropathy.
Comprehensive Summary on Guttural Pouch Tympany in Horses
Definition and Etiology
Guttural Pouch Tympany (GPT) is a condition characterized by the distension of one or both guttural pouches with air. It primarily affects young horses from birth to 1.5 years of age and is more common in fillies than in colts. The exact cause is often unknown, but it may involve a congenital defect or inflammation affecting the mucosal flap at the pharyngeal orifice.
Pathophysiology
• Abnormal Air Accumulation: Dysfunction or malformation of the plica salpingopharyngea creates a one-way valve effect, allowing air to enter the pouch but preventing its escape, leading to tympany.
• Potential Secondary Causes: In some cases, upper respiratory tract inflammation might contribute to the dysfunction.
Clinical Signs
• Characteristic Swelling: Nonpainful, fluctuant swelling in the parotid region (behind the jaw).
• Unilateral/Bilateral Tympany: Usually unilateral, but bilateral cases can occur.
• Respiratory Signs: Stertorous breathing, nasal discharge, and head carriage extension in severe cases.
• Complications: Dysphagia, dyspnea, secondary empyema, and aspiration pneumonia in complicated cases.
Diagnosis
• Clinical Signs: Based on observable swelling and respiratory signs.
• Radiographic Examination: X-rays of the skull to confirm the presence of air in the guttural pouch.
• Endoscopy: To confirm diagnosis, rule out other conditions, and distinguish between unilateral and bilateral disease.
Treatment
1. Conservative Management:
• NSAIDs: Nonsteroidal anti-inflammatory drugs to reduce inflammation.
• Antibiotics: Broad-spectrum antimicrobials if secondary infection is suspected.
2. Decompression:
• Percutaneous Needle/Catheter: Temporary relief by releasing air via a needle or catheter.
• Surgical Intervention:
• Fenestration: Creating a window between the affected and normal pouch to allow air escape.
• Foley Catheters: Long-term placement to remodel the mucosal flap and prevent air trapping.
Prognosis
• Good Prognosis: Most cases respond well to treatment, particularly if there are no secondary complications.
• Surgical Cases: May require repeated procedures, especially for bilateral tympany.
A nine-year-old female spayed cat is presented for polydipsia, polyuria and weight loss in spite of a voracious appetite. The cat has an unkempt coat and a rapid heart rate. The thyroid is palpably bilaterally enlarged.
What is the most common cause of feline hyperthyroidism?
Pituitary hyperplasia
Thyroid carcinoma
Hypercalcemic secondary parathyroidism
Functional thyroid adenoma
latrogenic
Answer: Functional thyroid adenoma
The most common cause of feline hyperthyroidism is a functional thyroid adenoma (adenomatous hyperplasia). In roughly 70% of cases, both thyroid lobes are affected.
Thyroid carcinoma is the primary cause of hyperthyroidism in dogs, but it is rare in cats (1-2% of hyperthyroidism cases).
Comprehensive Summary on Hyperthyroidism in Animals for BCSE Test Preparation
Definition and Etiology
Hyperthyroidism is a condition caused by excessive thyroid hormone production, primarily thyroxine (T4) and triiodothyronine (T3). In cats, it is usually due to thyroid adenomas or adenomatous hyperplasia. Thyroid carcinoma is a rare cause in cats but more common in dogs.
Pathophysiology
• Excessive Hormone Production: Leads to increased metabolic rate. • Adenomatous Hyperplasia: Most common in cats, leading to bilateral thyroid enlargement. • Thyroid Carcinoma: Common in dogs, causing similar clinical signs.
Clinical Signs
• Common Signs in Cats: • Hyperactivity, excessive vocalization, weight loss despite good appetite. • Vomiting, polyuria, polydipsia, tachycardia, and possible thyroid nodule. • In Dogs: Often associated with thyroid carcinoma; signs include weight loss, increased appetite, and possible palpable thyroid mass.
Diagnosis
• Clinical Signs and History: Key to initial suspicion. • Serum Thyroid Hormone Testing: Elevated total T4 or free T4 (fT4) concentrations confirm diagnosis. • Additional Tests: CBC, serum biochemistry, urinalysis to assess overall health and rule out concurrent diseases.
Treatment
1. Radioiodine Therapy: Preferred curative treatment; selectively destroys hyperactive thyroid tissue. 2. Antithyroid Medications: • Methimazole: Initial dose of 1.25–2.5 mg/cat every 12 hours, adjusted based on T4 levels. • Carbimazole: Similar to methimazole, converted to methimazole in the body. • Propylthiouracil: Not recommended due to severe side effects. 3. Surgical Thyroidectomy: Option for definitive treatment, especially in cases not suited for radioiodine therapy. 4. Iodine-Deficient Diet: Lifelong dietary management to limit iodine intake and reduce hormone production.
Medications
• Methimazole: Blocks thyroid hormone synthesis; dose adjustment based on response and side effects. • Carbimazole: Prodrug converted to methimazole; used where methimazole is tolerated. • Beta-Adrenoceptor Blockers (Propranolol, Atenolol): Used to control tachycardia and hypertension but do not affect thyroid hormone levels.
Monitoring and Follow-Up
• Regular Monitoring: Essential to adjust treatment and monitor for side effects or development of hypothyroidism. • Renal Function: Monitor as hyperthyroidism can mask underlying kidney disease.
Immediately after breeding, a three-year-old male poodle is unable to retract his penis back into the prepuce.
On exam, the penis is cyanotic and engorged and the dog is uncomfortable. The skin surrounding the preputial orifice is inverted, constricting the penis. No other abnormalities are observed.
What is the best treatment?
Do nothing; penile swelling will resolve and the penis will retract into the prepuce naturally
Gently cleanse and lubricate the penis; attempt to replace the penis into the prepuce
Administer general anesthesia; perform partial penectomy and orchiectomy
Administer local anesthesia, place a urinary catheter and perform a perineal urethrostomy
Administer a tranquilizer; surgically enlarge the preputial orifice and replace the penis into the prepuce
Answer: Gently cleanse and lubricate the penis; attempt to replace the penis into the prepuce
Paraphimosis is a medical emergency; gently cleanse and lubricate the penis and attempt to replace it into the prepuce.
Recognize and Tx quickly to prevent permanent damage to the penile and urethral tissue.
Tx goals: Reduce swelling, restore normal blood circulation, and replace the penis back into the prepuce. Use cold compresses or topical hypertonic solutions to reduce swelling. Administer sedation/pain medications as indicated.
In case such as this where the dog is presented immediately medical therapy may be successful. However, some cases require incision of the preputial skin to examine the preputial cavity and relieve venous obstruction.
https://www.merckvetmanual.com/reproductive-system/reproductive-diseases-of-the-male-small-animal/paraphimosis-in-dogs-and-cats
What part keeps exhaled gasses moving away from the patient in a circular rebreathing anesthetic delivery system?
One-way valves
Rebreathing bag
Oxygen flush valve
Y-valve on endotracheal tube
Passive scavenger
Answer: One-way valves
One-way valves help direct gas flow. Expired gasses pass through a CO2 scavenger canister to remove CO2.
STRATEGY HINT: See how the word “valve” occurs in 3 choices? Chances are that the correct answer contains this word.
To what approximate value should the anesthetic dial initially be set, in order to help most patients reach a surgical plane of anesthesia with an inhalant anesthetic agent such as
isoflurane? (Note: MAC = minimum alveolar concentration)
0.4 × MAC
2.0 x MAC
3.0 × MAC
Equal to MAC
1.5 × MAC
Answer: 1.5 x MAC
For most anesthetics and most patients, utilize a dial setting of approximately 1.5 x MAC as a guideline to help the patient reach a surgical plane of anesthesia. Adjust as needed based on how the patient is responding.
The minimum alveolar concentration (MAC) of an anesthetic agent is the percent concentration at which 50% of patients would not respond to surgical stimulation.
1.5 x MAC is a guideline only: assess the patient and use the appropriate MAC for the situation depending on the patient’s condition and pre-operative medications. It is critical to closely monitor patients under anesthesia and dose the anesthetic “to effect.”
What nerve or nerves need to be blocked in order to dehorn cattle?
Auriculopalpebral
Cornual and infratrochlear
Infratrochlear
Auriculopalpebral and infraorbital
Cornual
Answer: Cornual.
Typically a cornual nerve block (branch of the trigeminal- midway between eye and base of horn, just below temporal line) will anesthetize most cows for dehorning.
If that is not enough, do a ring block around the base of the horn.
In contrast, for goats you need to block BOTH the cornual nerve (caudal ridge, root of zygomatic arch of frontal bone) and infratrochlear nerve (dorsomedial to eye, close to edge of bony orbit) before dehorning.
This is because the goat horns lie more rostral on the skull and closer to the bony orbits than the horns of a cow.
A four-year-old Andalusian gelding is presented three days post-routine open castration performed in the field. The owner is concerned about the amount of swelling in the inguinal region.
The horse is eating, urinating, and defecating normally. Physical exam parameters are within normal limits.
The scrotal region and prepuce have moderate swelling with no drainage from the incisions.
What is the appropriate course of action?
Aseptic aspiration of this hydrocele, tell owner if it recurs surgery is indicated
Open and stretch the incisions, systemic NSAIDs, increase exercise
Identify hemorrhage source, place crushing forceps, pack incision w/ gauze
Ultrasound to confirm inguinal hernia, place support bandage, refer immediately for surgery
Institute systemic antimicrobials and anti-inflammatories, limit horse’s movement
Answer: Open and stretch the incisions, systemic NSAIDs, increase exercise.
This horse has routine postoperative swelling and the appropriate course of therapy is to open and stretch the incisions using sterile technique, administer systemic NSAIDs, and increase exercise to promote drainage.
Scrotal and preputial swelling and edema that peak at day 3-4 and resolve by day 10-12 are the most common complication following castration. In the absence of fever or significant pain/reluctance to move or urinate, the therapy noted above can be performed on the farm.
Between 20-38% of geldings experience a complication post-operatively. The 2nd-most common is hemorrhage.
The most serious is eventration of intestine through the incision. Additional complications include peritonitis, penile damage, and hydrocele (occurs months to years later).
Click here for an excellent article on the complications of castration, courtesy of Dr. Liberty Getman and the AAEP.
Intestinal Eventration after castration refers to the prolapse of intestinal contents through the surgical site. This condition is an emergency and is more likely in draft breeds, Tennessee Walking Horses, American Saddlebreds, Standardbreds, and adult stallions due to their larger inguinal rings.
Pathophysiology
• Post-Surgical Complication: Typically occurs within 4 hours to 6 days post-castration.
• Herniation Mechanism: Intestinal loops or omentum protrude through the inguinal canal.
Clinical Signs
• Visible Prolapse: Intestine or omentum hanging from the surgical site.
• Acute Pain: Due to stretching and possible strangulation of the intestine.
Diagnosis
• Physical Examination: Identification of protruding structures.
• Transrectal Palpation: To assess the extent of the prolapse.
Treatment
1. Omental Evisceration:
• Restraint and Sedation: Ensures the horse remains calm.
• Emasculation: Removal of the omentum if involved.
• Scrotal Packing and Closure: Sterile gauze and suturing.
• Antibiotics and NSAIDs: Prevent infection and manage pain.
2. Intestinal Evisceration:
• General Anesthesia: For safe examination and treatment.
• Intestinal Lavage: Clean and assess the intestine.
• Reduction or Surgical Referral: Depending on the damage, intestine may be reduced or referred for surgical resection.
Medications
• Broad-Spectrum Antibiotics: To prevent or treat infections.
• NSAIDs: For pain and inflammation control.
• Tetanus Prophylaxis: To prevent tetanus infection.
What is the function of the objects highlighted by the arrows below?
Remove red blood cell parasites
Engulf bacteria
Prevent phagocytosis
Help blood clot
Transport immunoglobulins
Answer: Help blood clot
These are thrombocytes (platelets), which help blood clot.
Formation of the platelet plug is the first step in hemostasis (“primary hemostasis”).
Platelets are also critical in formation of the fibrin plug (“secondary hemostasis”).
Follow these links to see clumps of bovine platelets and scattered feline platelets (and rouleaux formation - i.e., stacked up erythrocytes).
Res: McCurnin & Bassert, Clin Textbook for Vet Technicians, 9th ed. p. 384. Image courtesy of Dr. Seth Chapman.
Platelets in Animals - Key Points for Veterinary Professionals
Definition and Function
• Platelets: Cell fragments derived from megakaryocytes in the bone marrow.
• Role: Form initial hemostatic plug during hemorrhage, source of phospholipid for coagulation factors to form fibrin clots.
Physiopathology
• Production: Influenced by thrombopoietin, involves megakaryocyte membrane invagination and cytoplasmic fragmentation.
• Structure: Dense granules (ATP, ADP, calcium), serotonin, lysosomes, glycogen, mitochondria, intracellular canalicular system.
Hemostasis Process
1. Vessel Damage: Exposes collagen and tissue factor.
2. Platelet Adhesion: Via von Willebrand factor.
3. Shape Change: Release of ADP.
4. Aggregation: Forms primary platelet plug.
5. Fibrin Clot Formation: Consolidated by platelet contractile proteins.
Disorders
• Thrombocytopenia: Low platelet count (<30,000/μL), increased hemorrhage risk.
• Causes: Consumption (hemorrhage, DIC), destruction (immune-mediated), sequestration (hypersplenism).
• Symptoms: Petechiae, ecchymoses, mucosal bleeding.
• Thrombocytosis: Rare, often idiopathic or related to marrow disease.
• Thrombocytopathies: Normal count, impaired function (e.g., von Willebrand disease, aspirin-induced thromboxane inhibition).
Medications and Management
• Treatment for Thrombocytopenia: Address underlying cause, immunosuppressants for immune-mediated cases.
• Thrombocytosis: Address primary condition, if identified.
• Platelet Function Disorders: Avoid causative drugs, supportive care.
An adult ewe is presented after she was found wandering aimlessly and pressing her head into the walls of the barn. Now she is recumbent.On presentation the ewe has no menace response. Her pupillary light reflex (PLR) is intact bilaterally and she displays opisthotonos and nystagmus. Which one of the following conditions is the top differential diagnosis?
Answer: Poliencephalomalacia
This is most consistent with polioencephalomalacia, which can affect all ruminants sporadically or occasionally in herd outbreaks.
Remember cortical blindness (i.e., no menace, positive PLR bilaterally) in a ruminant is highly suggestive of polioencephalomalacia.
The signs seen with polioencephalomalacia are due to a disruption in cerebral energy metabolism, which causes swelling and necrosis of neurons within the central nervous system.
Can be due to thiamine deficiency, sodium/lead/sulfur toxicosis, or water deprivation. Dx usually based on clinical signs and positive response to thiamine administration.
Listeriosis may cause similar signs of disorientation/recumbency, but usually also unilateral cranial nerve deficits (e.g., head tilt, ear droop) and continuous salivation and food impacted in the cheek of the affected side.
Thrombotic meningoencephalitis (TME) caused by Histophilus somni (formerly Haemophilus somnus) is a common cattle disease in North America which may present with only depression, or sudden death in multiple animals. Histophilosis it is NOT common in sheep though it can occur. Click here to see a report on Histophilus somni in bighorn sheep.
Polioencephalomalacia in Ruminants - Comprehensive Study Guide
Definition
• Polioencephalomalacia (PEM): A neurologic disease in ruminants, characterized by cerebrocortical necrosis.
Causative Agents
• Primary Causes: Thiamine deficiency and high sulfur intake.
• Other Causes: Acute lead poisoning, sodium toxicosis, water deprivation, and toxic plants containing thiaminase.
Pathophysiology
• Thiamine Deficiency: Thiamine is essential for glucose metabolism in the brain. Deficiency leads to impaired glucose metabolism, energy depletion, and neuronal necrosis.
• High Sulfur Intake: Sulfur is reduced to hydrogen sulfide (H2S) in the rumen, which interferes with cellular energy metabolism, particularly in the CNS.
Clinical Signs
• Acute Form: Blindness, recumbency, seizures, coma, high mortality.
• Subacute Form: Separation from group, incoordination, cortical blindness, head pressing, opisthotonos, recumbency, seizures, potentially recovery with minor neurologic impairment.
Lesions
• Gross Lesions: Brain swelling, gyral flattening, cerebellar coning, yellowish discoloration of cortical tissue, autofluorescent necrotic bands.
• Microscopic Lesions: Necrosis of cerebrocortical neurons, cortical spongiosis, vascular hypertrophy and hyperplasia, cavitation of cortical tissue.
Diagnosis
• Clinical Signs: Blindness, head pressing, seizures.
• Necropsy: Autofluorescent bands in the cerebral cortex under UV light.
• Histology: Characteristic neuronal necrosis and cavitation.
• Differential Diagnoses: Lead poisoning, sodium toxicosis, histophilosis, rabies, vitamin A deficiency, pregnancy toxemia, clostridial enterotoxemia, listeriosis.
Treatment
• Thiamine Administration: 10 mg/kg IV initially, then IM for 3-5 days.
• Supportive Therapy: Dexamethasone or mannitol for cerebral edema, symptomatic therapy for seizures.
• Response to Treatment: Improvement usually seen within 24 hours; continued treatment for ≥3 days if no initial response.
Prevention
• Dietary Management: Thiamine supplementation (3-10 mg/kg feed).
• Sulfur Management: Monitor and control sulfur intake from water and feed, especially during hot weather.
Lymnaeid snails are intermediate hosts for which parasite of ruminants?
Answer: Fasciola hepatica
Lymnaeid snails are the intermediate hosts for trematode flukes like Fasciola hepatica and Fascioloides magna.
Link: Fasciola hepatica in Ruminants
https://www.merckvetmanual.com/digestive-system/fluke-infections-in-ruminants/fasciola-hepatica-in-ruminants
https://www.merckvetmanual.com/multimedia/image/fasciola-hepatica-adult
https://en.m.wikipedia.org/wiki/Fascioloides_magna
Fasciola hepatica in Ruminants - Comprehensive Study Guide
Definition
• Fascioliasis: Liver fluke disease caused by Fasciola hepatica, affecting cattle, sheep, alpacas, and llamas.
Causative Agent
• Fasciola hepatica: A liver fluke causing chronic, subacute, and acute infections, with adults residing in bile ducts.
Pathophysiology
• Transmission: Ingestion of metacercariae on vegetation.
• Life Cycle: Eggs hatch in water, miracidia infect snails, asexual development to cercariae, which encyst on vegetation as metacercariae. After ingestion, young flukes excyst in the duodenum, migrate to the liver, and mature in bile ducts.
• Damage: Immature flukes cause hepatic necrosis and hemorrhage, mature flukes cause bile duct fibrosis and calcification.
Clinical Signs
• Acute Disease: Painful abdomen, anemia, sudden death in sheep.
• Subacute Disease: Anemia, hemorrhage, extended survival with hepatic damage.
• Chronic Disease: Anemia, weight loss, decreased milk production, submandibular edema, especially in cattle.
Lesions
• Acute: Enlarged, friable liver with fibrinous deposits.
• Chronic: Cirrhosis, enlarged bile ducts, fibrosis, calcification in cattle.
Diagnosis
• Fecal Sedimentation: Detects eggs.
• ELISA: Detects antibodies in serum or milk.
• Necropsy: Identifies adult flukes and liver damage.
Treatment
• Anthelmintics: Triclabendazole, clorsulon, albendazole, nitroxinil, closantel, rafoxanide, oxyclozanide.
• Resistance: Documented resistance to albendazole, clorsulon, and triclabendazole.
Control
• Pasture Management: Reduce snail habitats, avoid grazing high-risk pastures.
• Snail Control: Molluscicides (historically used, now mostly banned).
A three-month-old male shelter puppy is presented with a three-week history of diarrhea with pale, malodorous stools that contain mucus. On physical exam the puppy appears thin but bright and alert. Wet-mounts, shown below, after zinc sulfate fecal flotation reveal cyst-like structures, roughly 12-18 micrometers in length, stained with trichrome. What is the diagnosis?
Answer: Giardia lamblia
This is a cyst of the flagellate protozoan Giardia lamblia found in the intestinal tracts of humans and most animals. Most infections do not cause clinical signs, but diarrhea and steatorrhea can occur, particularly in puppies and kittens.
Giardiasis must be differentiated from exocrine pancreatic insufficiency (EPI) and other malabsorption syndromes.
Amebiasis due to Entamoeba histolytica presents as an acute or chronic colitis, with persistent diarrhea or dysentery (mucus, blood in the stool, fever, abdominal pain).
More prevalent in tropical and subtropical countries than in North America. Click here to see an image of Entamoeba histolytica.
Link: Exocrine Pancreatic Insufficiency in Dogs and Cats
https://www.merckvetmanual.com/digestive-system/the-exocrine-pancreas/exocrine-pancreatic-insufficiency-in-dogs-and-cats?redirectid=31744
Link: Malabsorption Syndromes in Small Animals
https://www.merckvetmanual.com/digestive-system/diseases-of-the-stomach-and-intestines-in-small-animals/malabsorption-syndromes-in-small-animals
Link: Entamoeba histolyticaAmebiasis
https://www.merckvetmanual.com/digestive-system/amebiasis/entamoeba-histolytica-amebiasis?autoredirectid=19848
https://www.merckvetmanual.com/multimedia/image/entamoeba-histolytica-cyst
https://www.cdc.gov/dpdx/giardiasis/index.html
A one-year-old Angus cow, shown in the image below, is presented with multifocal, circular, alopecic, and crusty lesions, mainly affecting the head and neck. Three other cows have also recently developed similar skin lesions. Dermatophytosis is the suspected problem. Which one of the following choices is the primary dermatophyte in cattle?
Answer: Trichophyton verrucosum
Trichophyton verrucosum is the primary dermatophyte in cattle, most commonly seen in calves as periocular lesions although it can become generalized. More common among younger animals and is non-pruritic.
Tx is not usually required as cattle often spontaneously recover.
There are no approved antifungal agents in cattle. Antifungals approved in other animals or humans could be used if a meat and milk withdrawal time can be determined.
Microsporum canis is commonly found in dogs and cats, and Trichophyton mentagrophytes in rodents.
Link: Dermatophytosis in Cattle
https://www.merckvetmanual.com/integumentary-system/dermatophytosis/dermatophytosis-in-cattle
Dermatophytosis in Cattle - Comprehensive Veterinary Information
Definitions and Terminology:
• Dermatophytosis (Ringworm): A fungal infection affecting the skin of cattle.
Causative Agents:
• Primary: Trichophyton verrucosum.
• Others: Trichophyton mentagrophytes, Trichophyton equinum, Microsporum gypseum, Microsporum nanum, Microsporum canis.
Physiopathology:
• Transmission: Direct contact with infected animals or fomites.
• Pathogenesis: Fungi invade keratinized tissues, causing characteristic lesions.
Clinical Findings:
• Lesions: Discrete, scaling patches of hair loss with gray-white crusts.
• Locations:
• Calves: Periocular areas.
• Cows/Heifers: Chest and limbs.
• Bulls: Dewlap and intermaxillary skin.
Diagnosis:
• Clinical Signs: Visual inspection of characteristic lesions.
• Laboratory Tests: Fungal culture, microscopic examination of hair/skin scrapings.
Treatment:
• Topical Therapy: Lime sulfur (1:16), enilconazole (1:100).
• Improving Husbandry: Reducing overcrowding, improving hygiene.
• Vaccination: Live-attenuated fungal vaccine (not available in North America).
Prevention:
• Hygiene: Regular cleaning, burning infective material.
• Isolation: Separate infected animals to prevent spread.
A nursing lamb has multiple vesicles, pustules, and large coalescing crusts on the lips and oral mucosa. The ewe has large friable crusts and granulation tissue on the teats and udder. What is the most likely diagnosis?
Answer: Contagious Ecthyma.
If you hear “crusty lips/ears” on a goat or sheep, think of contagious ecthyma, also called “orf” or “soremouth.”
Caused by a parapoxvirus which enters the body through cuts. See papules, pustules, and thick friable scabs on the lips, mouth, nose, ears, and feet; and on the udders of lactating does and ewes.
Treatment is supportive. Orf/soremouth is common, very contagious, and zoonotic, so be careful when you handle infected animals, as humans are also at risk of developing crusty sores. In endemic areas, young animals are most susceptible.
Goat and sheep-pox are serious, foreign animal diseases. Follow this link to see sheep-pox: NOT found in North America and reportable.
For good refs on Foreign Animal Diseases (FADs), download the newly revised 7th edition of The Gray Book (Note- this is a large PDF file, it will take a minute to load), available free online courtesy of the U.S. Animal Health Association.
For a fast online search, try the Center for Food Security and Public Health (CSFPH) Zoonosis website.
Link: Contagious Ecthyma in Sheeps and Goats.
https://www.merckvetmanual.com/integumentary-system/pox-diseases/contagious-ecthyma-in-sheep-and-goats?autoredirectid=21714
https://www.merckvetmanual.com/multimedia/image/sheeppox-lesions
Link: Foreign Animal Diseases
https://www.usaha.org/upload/Disease Info/FAD.pdf
Link: Zoonotic Diseases
https://www.cfsph.iastate.edu/zoonoses/
Contagious Ecthyma in Sheep and Goats - Detailed Veterinary Summary
Etiology and Pathogenesis
• Causative Agent: Parapoxvirus
• Transmission: Direct contact, fomites; virus highly resistant in the environment
• Pathogenesis: Entry through skin abrasions, viral replication in keratinocytes causing cytoplasmic swelling and degeneration, leading to vesicle formation and subsequent pustules.
Clinical Findings
• Symptoms: Papules, vesicles, pustules primarily on lips, face, feet, teats, occasionally buccal cavity and feet; anorexia, weight loss, secondary infections
• Lesions: Progress from macules to papules, vesicles, pustules, and scabs; most common at mucocutaneous junctions
Diagnosis
• Tests:
• PCR: Gold standard for detecting viral DNA in scabs
• Electron Microscopy: Identification of characteristic viral particles
• Histopathology: Intracytoplasmic inclusion bodies
• Differential Diagnosis: Foot-and-mouth disease, bluetongue, ulcerative dermatosis
Treatment and Control
• Medications:
• Antimicrobials: Prevent secondary bacterial infections
• Topical Treatments: Prevent myiasis, soothing ointments for lesions
• Vaccination: Live virus vaccines, typically prepared from infected scab material; administered by scarification, providing immunity but with caution due to zoonotic risk
Prevention
• Hygiene and Management: Regular disinfection of equipment, isolation of infected animals, proper handling of infected materials
• Biosecurity: Prevent introduction from new animals, quarantine measures
• Environmental Control: Reducing contamination of grazing areas, maintaining dry conditions to minimize virus persistence
Key Points
• Zoonotic Potential: Can cause orf in humans, characterized by painful pustules, particularly on hands; use of gloves and proper hygiene essential during handling
• Resilience: Virus can survive in scabs for years; thorough cleaning and disinfection required to prevent environmental persistence
• Public Health Considerations: Inform handlers of zoonotic risk, ensure proper wound care and protection when dealing with infected animals
A budgerigar is presented that looks like the image below. What is the diagnosis?
Answer: Knmidocoptes pilae.
This is Knemidocoptes pilae, the scaly face (or leg) mite and this appearance is considered pathognomic. Confirm Dx with facial scraping if indicated.
Tx with ivermectin (0.2 mg/kg IM or PO) or moxidectin (0.2 mg/kg PO) repeated in two weeks. Tx is generally curative but beak deformity may persist.
In passerine birds (esp. canary, European goldfinch), look more for crusts on legs, digits (“tassel foot”). Do not perform leg scrapings for diagnosis as this can result in excessive hemorrhage.
Link: Parasitic diseases of Pet Birds.
https://www.merckvetmanual.com/exotic-and-laboratory-animals/pet-birds/parasitic-diseases-of-pet-birds
A small kitten is presented with an open wound in the right ventral neck containing a 1.2-inch (3-cm) long parasite covered in tiny black spines. What is the organism?
Answer: Cuterebra.
Cuterebra (a.k.a. rabbit botfly larva) is occasionally found in outdoor-roaming cats and dogs. In North America, cases are usually seen during late summer and fall. The visible fistula is a breathing hole for the larva which eventually exits, pupates and becomes a fly.
The normal hosts are rabbits, squirrels, chipmunks and mice. Cuterebra flies lay eggs near the nests, burrows, and traffic pathways where they can attach to the body of hosts. The eggs hatch in response to body heat and larvae enter the body via the mouth or nostrils during grooming, but may also enter through a wound. They penetrate the tissues and travel to specific subcutaneous areas where they mature.
Extract the larva carefully in one piece to avoid a severe local inflammatory reaction that can result from a ruptured grub. Do not squeeze the area as that might damage the larva.
Anaphylaxis in response to rough removal has also been reported anecdotally.
If there is only a swelling without an obvious breathing hole (yet), an abscess or foreign body are ruleouts for this lesion.
Cattle grubs (Hypoderma spp.) are generally lighter colored with less prominent spines and are rarely found in pets.
The larvae that cause cutaneous habronemiasis are tiny - they emerge from infected flies feeding on wounds and invade the damaged tissue.
Horse bots (Gasterophilus spp.) live in the stomach and are not known to infect dogs and cats.
ies feeding on wounds and invade the damaged tissue.
Sheep nose bots (Oestrus ovis) are smaller than cuterebrae larva. They live in the nares and only affect sheep and goats.
- Cuterebra larvae: seen in outdoor cats/dogs, late summer/fall.
- Larvae enter through grooming wounds, mature subcutaneously.
- Extract larvae carefully to avoid severe inflammation, anaphylaxis.
Link: Cuterebra infestation in Dogs and Cats.
https://www.merckvetmanual.com/integumentary-system/cuterebra-infestation-in-dogs-and-cats/cuterebra-infestation-in-dogs-and-cats
Link: Hypoderma spp.
https://www.merckvetmanual.com/integumentary-system/cattle-grubs/hypoderma-spp
Link: Cutaneous Habronemiasis in Animals.
https://www.merckvetmanual.com/integumentary-system/helminths-of-the-skin/cutaneous-habronemiasis-in-animals
Link: Gasterophilus spp Infection in Horses
https://www.merckvetmanual.com/digestive-system/gastrointestinal-parasites-of-horses/gasterophilus-spp-infection-in-horses?redirectid=27858
Link: Sheep Nasal bot myiasis
https://www.merckvetmanual.com/respiratory-system/respiratory-diseases-of-sheep-and-goats/sheep-nasal-bot-myiasis?autoredirectid=19854
A three-year-old female spayed mixed breed dog is presented for recheck of idiopathic epilepsy diagnosed one month previously. The dog has had two seizures in the past two weeks and is currently receiving phenobarbital at 3 mg/kg PO q 12 h and potassium bromide at 30 mg/kg PO q 24 h. Physical exam is unremarkable. What is the most appropriate next step?
Answer: Discontinue phenobarbital in this dog.
Discontinue phenobarbital in this dog with neutropenia, thrombocytopenia, and mild anemia. This is a rare side effect of treatment, seen most commonly in the first three months of treatment. Monitor the CBC during this period because changes are typically reversible when detected early.
Taper phenobarbital over seven days to reduce the risk of breakthrough seizures, which could result in status epilepticus.
Add another anti-epileptic drug (e.g., levetiracetam) in this dog because of continued seizures and the need to discontinue phenobarbital.
Monitor liver enzymes and serum phenobarbital concentration every 6 to 12 months in dogs receiving chronic phenobarbital therapy because liver enzyme increase is common. While it does not necessarily indicate hepatic dysfunction, ALT or ALP > 5 x reference range, increased GGT, hyperbilirubinemia, or increased serum bile acid concentration is concerning for phenobarbital-induced hepatic dysfunction.
If these chemistry changes occur consider tapering/discontinuing phenobarbital and adding another anti-convulsant. Hepatic dysfunction/failure are typically seen with higher serum phenobarbital concentrations.
Other potential side effects of phenobarbital include polyuria/ polydipsia/polyphagia. Phenobarbital can affect the results of thyroid testing and falsely lower total and free T4 and increase TSH. Dogs with these findings do not have hypothyroidism, so do not initiate Tx based on thyroid hormone measurement in patients on phenobarbital.
Link: Phrnobarbital
https://www.merckvetmanual.com/pharmacology/systemic-pharmacotherapeutics-of-the-nervous-system/maintenance-anticonvulsant-or-antiepileptic-therapy#Phenobarbital:_v4502428
Phenobarbital:
Phenobarbital has a long record of safety, efficacy, low cost, and convenience in regard to monitoring serum concentrations. For longterm maintenance in cats and dogs, phenobarbital may be given at 2-4 mg/kg/day, PO, bid.
In all species, it takes ~2 wk to approach a steady-state plasma concentration, because oral absorption is extremely variable and the half-life is long. Drug levels are monitored 2 wk after initiation of therapy, 2 wk after any dosage change, and usually every 6-12 mo once seizure control is achieved. Serum therapeutic concentrations are 15-45 mcg/mL. The dosage should be adjusted on the basis of serum level and the history of seizure control. Tolerance to phenobarbital therapy may develop in dogs treated continually for months to years and may result in decreased seizure control; however, an increase (25%) in the dose usually will result in improved seizure control.
Phenobarbital causes physical dependence, and thus abrupt withdrawal may cause “barbiturate withdrawal” seizures. Hepatotoxicity and liver failure in dogs have been associated with high serum concentrations (>35 mcg/mL), necessitating the serum level checks every 6-12 mo. Adverse effects such as sedation, polydipsia, polyuria, and polyphagia are common but may decrease within the first few weeks. Other, less common adverse effects are idiosyncratic hyperexcitability, dermatitis, anemia, neutropenia, thrombocytopenia, gingival hyperplasia, and osteomalacia. Phenobarbital has also been used to treat episodic dyscontrol syndrome (rage) in dogs when seizure activity is demonstrable via electroencephalogram recordings.
Oral phenobarbital has been used in ruminants at 11 mg/kg/day and in horses at 3-11 mg/kg/day. Serum concentrations should be checked periodically.
Which one of the following findings is normal on a complete blood count (CBC) in a cat?
High red cell concentration (polycithemia)
Wanthochromic (yellow) serum
Irregularly shaped red cells (schistocytosis)
Clumped platelets
Lipemic (fatty) serum
Answer: Clumped platelets.
Feline platelets (thrombocytes) clump easily. When counting platelets in cat blood, either manually or with an automated cell counter, this must be taken into account.
Feline platelets, essential in hemostasis, are produced in the bone marrow and have a typical lifespan of about 5-7 days. They play a crucial role in primary hemostasis, adhering to damaged endothelial cells and forming a platelet plug. In addition, they contribute to secondary hemostasis by providing a surface for coagulation factor activation. Platelets also have functions beyond clot formation, including roles in immune responses and maintaining vascular integrity. Their production, structure, and function are complex, involving various cytokines and cellular processes. For veterinary professionals, understanding the nuances of feline platelet physiology is crucial, particularly in diagnosing and managing hematologic and vascular disorders.
Feline platelets no clumping, but normal rouleaux formation is clearly demonstrated.
https://www.merckvetmanual.com/multimedia/v4730684
Equine platelets (hard to see-they don’t stain well
https://www.merckvetmanual.com/multimedia/v4730819
Bovine platelets on a blood smear.
https://www.merckvetmanual.com/multimedia/v4730756
Refs: Bassert, Beal and Samples, McCurnin’s Clinical Textbook for Velerinary Technicians, gthed, pp. 373. Duncan and Prasse’s Clinical Pathology, 4t! ed. p.105.
Platelets - Comprehensive Study Guide
Definitions and Production
• Platelets: Anucleate cell fragments produced in the bone marrow from megakaryocytes, essential for hemostasis.
• Production: Stimulated by thrombopoietin from the liver and bone marrow stromal cells. Other cytokines like IL-6, IL-11, GM-CSF also play roles.
Physiopathology
• Formation: Megakaryocytes undergo endomitosis and cytoplasmic maturation, extending proplatelets into vascular sinuses.
• Senescence: Platelets circulate for 5-7 days, undergoing desialylation and apoptosis, removed by liver Kupffer cells and spleen macrophages.
Functions
• Hemostasis: Platelets adhere to damaged endothelium, aggregate, and form a hemostatic plug. They also release granules containing ADP, thromboxane A2, and other factors to promote coagulation.
• Vascular Integrity: Platelet-derived factors maintain endothelial junctions and support angiogenesis.
• Immune Roles: Platelets phagocytize pathogens and modulate immune responses.
Medications
• Thrombopoietin Receptor Agonists: Used in treating refractory thrombocytopenia in humans.
Structure
• Granules:
• Alpha Granules: Contain proteins for adhesion, inflammation, and coagulation.
• Dense Granules: Contain ATP, ADP, serotonin, calcium.
• Lysosomes: Contain hydrolytic enzymes.
