Equine I Flashcards
What is the function of platelets in hemostasis?
They form a platelet plug within about 5 minutes after vascular injury.
What are the three primary reactions of platelets after endothelial disruption?
Adhesion and shape change
What factor is necessary for platelet adhesion to the subendothelium?
Von Willebrand factor (vWF).
What is the final product of the coagulation cascade?
A cross-linked fibrin clot that stabilizes the platelet plug.
How does thrombin regulate clot formation?
Thrombin is absorbed into fibrin fibers and inactivated by anti-thrombin to prevent excessive clotting.
How does heparin work as an anticoagulant?
It binds to anti-thrombin and enhances its ability to prevent clot formation.
What are key clinical signs of platelet dysfunction?
Petechiae
What is the key test for primary hemostasis?
Platelet count and buccal mucosal bleeding time (BMBT).
At what platelet count do spontaneous bleeds typically occur?
Less than 30
What is the normal buccal mucosal bleeding time (BMBT)?
Less than 4 minutes.
What test is used to evaluate the intrinsic and common pathways?
Activated Clotting Time (ACT) and Activated Partial Thromboplastin Time (PTT).
What is the normal ACT range?
60-90 seconds.
Which clotting factors does ACT assess?
Prekallikrein
Which test is more sensitive for intrinsic pathway evaluation: ACT or PTT?
PTT is more sensitive than ACT.
What test is used to evaluate the extrinsic and common pathway?
Prothrombin Time (PT).
Which clotting factors does PT assess?
Factors X
What is the most common platelet disorder in Doberman Pinschers?
Von Willebrand’s Disease.
What is the inheritance pattern of Von Willebrand’s Disease in Dobermans?
Autosomal dominant with variable penetrance.
How is Von Willebrand’s Disease treated before surgery?
DDAVP (Desmopressin) 1μg/kg given 30 minutes before induction
What clotting factor is deficient in Hemophilia A?
Factor VIII.
What clotting factor is deficient in Hemophilia B?
Factor IX.
Which coagulation tests are elevated in Hemophilia A and B?
ACT and PTT.
What clotting disorder results from rodenticide toxicity?
Vitamin K deficiency.
Which clotting factors are affected by Vitamin K deficiency?
Factors II
Which coagulation tests are elevated in Vitamin K deficiency?
PT and PTT.
What is the half-life of Factor VII
making it an early indicator of Vitamin K deficiency?
How long does it take for clinical bleeding to develop in Vitamin K deficiency?
1-2 days.
What is the treatment for rodenticide toxicity?
Vitamin K1 for approximately 4 weeks.
Why should clotting times be rechecked after Vitamin K1 therapy?
To ensure the rodenticide has been completely eliminated.
What is the mnemonic for the common coagulation pathway?
2 x 5 x 1 = 10 (Factors II
What is the mnemonic for the intrinsic coagulation pathway?
I shop at Wal-Mart because everything is under $12. It is always $11.98 (Factors XII
What is the prognosis for hepatobiliary diseases in horses?
Variable; acute serum hepatitis has a guarded to poor prognosis
What is the most common cause of acute hepatitis and hepatic failure in horses?
Acute Serum Hepatitis (Theiler’s Disease).
What is Theiler’s Disease associated with?
Possible administration of tetanus antitoxin or other equine biologicals 4-10 weeks prior to onset.
What are the clinical signs of acute serum hepatitis?
Acute depression
What are the microscopic findings in acute serum hepatitis?
Widespread hepatic necrosis
What is the treatment for acute serum hepatitis?
Supportive therapy: fluid therapy
What necropsy findings are observed in acute serum hepatitis?
Severe decrease in liver size
What is the prognosis for acute serum hepatitis?
Favorable if no severe hepatoencephalopathy; poor if there are signs of bleeding or hepatic encephalopathy.
What is chronic active hepatitis in horses?
Chronic inflammatory liver disease of unknown etiology.
What are potential causes of chronic active hepatitis?
Plant or chemical toxins
What are the clinical signs of chronic active hepatitis?
Progressive weight loss
What are the diagnostic findings in chronic active hepatitis?
Fibrosis in portal areas
How is chronic active hepatitis treated?
Corticosteroids
What is the prognosis for chronic active hepatitis?
Fair to good if mild fibrosis and response to steroids; poor if chronic hepatic changes or hepatic failure.
What causes pyrrolizidine alkaloid (PA) toxicity in horses?
Consumption of plants containing pyrrolizidine alkaloids (PA)
What are common plants that contain pyrrolizidine alkaloids?
Senecio spp.
What is the pathophysiology of PA toxicity?
Toxin is absorbed
What is the characteristic cellular change in PA toxicity?
Megalocytosis: hepatocytes enlarge as their cytoplasm expands without nuclear division.
What are the clinical signs of PA toxicity?
Weight loss
How is PA toxicity diagnosed?
History of consumption of PA-containing plants
What is the treatment for PA toxicity?
Remove PA-containing plants
What is the prognosis for PA toxicity?
Dependent on the degree of hepatic change.
What are common risk factors for laminitis?
Metabolic disease (Equine Cushing’s
What is the pathogenesis of laminitis?
Inflammation weakens the laminar projections
What are clinical signs of laminitis?
Rocked-back stance
What radiographic changes are seen in laminitis?
Coffin bone rotation
What is the initial treatment for laminitis?
Icing feet
What breeds are predisposed to navicular syndrome?
Quarter Horses
What are clinical signs of navicular syndrome?
Bilateral front limb lameness that switches between limbs after blocking
What radiographic findings are associated with navicular disease?
Increased nutrient foramina
What are treatment options for navicular syndrome?
Corrective shoeing (shortening toe
What tendons and ligaments are most commonly affected in equine lameness?
Suspensory ligament (especially proximally)
What is Degenerative Suspensory Ligament Desmitis (DSLD)?
A progressive failure of collagen repair in the suspensory ligament
How is tendonitis diagnosed?
Ultrasound showing focal anechoic lesions
What is the treatment for tendonitis?
Rest
What are common names for osteoarthritis based on location?
High ringbone (pastern joint OA)
What radiographic changes are seen in OA?
Osteophytes
What are treatment options for OA?
NSAIDs (phenylbutazone
What are risk factors for hoof abscesses?
Wet or muddy conditions
What are clinical signs of a hoof abscess?
Severe acute lameness (sometimes non-weight-bearing)
How is a hoof abscess treated?
Hoof soaking (Epsom salts
What are common clinical signs of a septic joint?
Severe lameness
How is a septic joint diagnosed?
Arthrocentesis with WBC >30
What is the treatment for septic arthritis?
Joint lavage
What is the prognosis for untreated septic arthritis?
Poor; secondary osteoarthritis leads to long-term lameness.
What are risk factors for OCD?
Rapid growth
What are common sites of OCD in horses?
Tarsus
How is OCD diagnosed?
Radiographs showing subchondral bone cysts
What is the treatment for OCD?
Conservative management in young horses
What are common sites of congenital flexural limb deformities?
Carpus and fetlock.
What are clinical signs of flexural deformities?
Contracted tendons preventing full extension
How are mild flexural deformities treated?
Splinting
What is the treatment for severe flexural deformities?
Desmotomy if unresponsive to conservative treatment.
What are risk factors for septic arthritis in foals?
Failure of passive transfer (IgG <800 mg/dL)
What are clinical signs of septic arthritis in foals?
Joint effusion
How is septic arthritis diagnosed?
Arthrocentesis with WBC >30
What is the treatment for septic arthritis in foals?
Systemic and intra-articular antibiotics (amikacin
What is a malunion?
A healed fracture in which anatomical bone alignment was not achieved or maintained during healing.
What is a common consequence of malunions in the appendicular skeleton?
Angular deformity.
What is the difference between minor and major angular deformities?
Minor: <10% in any plane or <10% loss of original length; Major: anything beyond this
What is a common site for malunions
and what problem can it cause?
What are common causes of malunions?
Improper treatment of original fracture
How is a malunion diagnosed?
Radiographs to determine extent of angular
What is a varus deformity?
Deviation of the segment axis towards the median sagittal plane.
What is a valgus deformity?
Deviation of the segment axis away from the median sagittal plane.
What is procurvatus?
Cranial bowing deformity in the sagittal plane.
What is recurvatus?
Caudal bowing deformity in the sagittal plane.
What is pronatus?
Internal rotation deformity in the axial plane.
What is supinatus?
External rotation deformity in the axial plane.
What is the treatment for malunions that cause functional problems?
Corrective osteotomy.
What is an important step before corrective osteotomy?
Preoperative planning.
What type of fixator can be used for bone lengthening and angular corrections?
Ring fixator.
What is an advantage of using a ring fixator in malunion correction?
Allows gradual stretching of muscles
What is Neonatal Isoerythrolysis (NI)?
A type II hypersensitivity reaction where maternal antibodies destroy a foal’s red blood cells (RBCs) after colostrum ingestion.
Which foals are most at risk for NI?
Foals born to multiparous mares.
At what age do foals typically present with NI?
Less than 7 days old
What is a key clinical sign of NI?
Icteric mucous membranes and sclera.
Which erythrocyte antigens are most commonly implicated in NI?
Aa and Qa factors.
What type of hypersensitivity reaction is NI?
Type II hypersensitivity reaction.
How do foals acquire maternal alloantibodies leading to NI?
By ingesting colostrum containing antibodies against their RBC antigens.
What must be present for a foal to develop NI?
1) Neonatal RBC antigen inherited from the sire that the mare does not express
How does a mare develop antibodies against RBC antigens?
Previous exposure through blood transfusion
Why do mule foals have a higher incidence of NI?
Donkeys have a unique ‘donkey factor’ RBC antigen that horses do not express.
What are the clinical signs of NI?
Tachycardia
What determines the severity of NI in foals?
The amount of maternal antibodies absorbed via colostrum.
What are key diagnostic findings in NI?
Hyperbilirubinemia and anemia.
How is NI confirmed?
Cross-matching the foal’s RBCs with the mare’s serum (Jaundice Foal Agglutination Test).
What is the treatment for NI if recognized in the first 24 hours?
Withhold dam’s colostrum
What is the treatment for NI after 24 hours of age?
Monitor PCV; if PCV < 12%
What supportive care should be provided to foals with NI?
Minimize stress and exercise
What is the prognosis for foals with NI?
Good with proper treatment
Why is client education important in NI cases?
To prevent recurrence in future pregnancies.
What risk does severe anemia (<10% PCV) pose in NI?
Limited time to acquire blood for transfusion
What is the purpose of diagnostic nerve blocks in equine lameness exams?
To localize the source of lameness by desensitizing specific regions of the limb.
Where is the palmar digital nerve block administered?
Around the medial and lateral palmar digital nerves between the proximal sesamoid bones and just proximal to the cartilages of the foot.
What areas are desensitized by the palmar digital nerve block?
50-70% of the palmar/plantar aspect of the foot
Where is the abaxial sesamoid block administered?
Around the medial and lateral palmar digital nerves over the abaxial surface of the proximal sesamoid bones.
What areas are desensitized by the abaxial sesamoid block?
Skin over the palmar pastern
Which nerves are blocked in the low four-point block?
Medial and lateral palmar nerves and medial and lateral palmar metacarpal nerves.
Where is the low four-point block administered?
Palmar nerves: between the suspensory ligament and deep digital flexor tendon; Palmar metacarpal nerves: just distal to the end of the splint bones.
What areas are desensitized by the low four-point block?
Entire metacarpophalangeal (fetlock) joint and all structures distal to this joint.
Which nerves are blocked in the high four-point (subcarpal) block?
Medial and lateral palmar nerves and medial and lateral palmar metacarpal nerves just distal to the carpus.
Where is the high four-point block administered?
Palmar nerves: between the suspensory ligament and deep digital flexor distal to the carpus; Palmar metacarpal nerves: axial to the splint bones and abaxial to the suspensory ligament.
What areas are desensitized by the high four-point block?
Metacarpal region
If a horse’s lameness resolves by 85% after a low four-point block
what is the most likely location of the problem?
Why is a general understanding of equine nerve blocks important for the NAVLE?
To correctly answer questions about which block anesthetizes which area
What are common clinical signs of pneumonia in horses?
Cough
What history factors predispose horses to pneumonia?
Extended transport
What is pleuropneumonia?
Pneumonia with significant accumulation of fluid and fibrin in the pleural cavity.
What is aspiration pneumonia
and what causes it?
What are common bacterial causes of pneumonia?
Streptococcus zooepidemicus (Gram+)
What viruses predispose horses to bacterial pneumonia?
Equine Herpes Virus
What fungal pathogens may cause pneumonia?
Coccidiodes
What are common clinicopathologic abnormalities in equine pneumonia?
Leukopenia (acute) to leukocytosis (chronic)
What diagnostic tests are used for pneumonia?
Thoracic radiography
What radiographic findings are common in pneumonia?
Radiopacity of cranial-ventral or caudal-ventral thorax
What ultrasonographic findings are common in pleuropneumonia?
Free pleural fluid
What are key components of pneumonia treatment?
Antimicrobials
What antibiotics are commonly used for bacterial pneumonia?
Penicillin or cephalosporin + aminoglycoside; metronidazole for anaerobes.
What anti-inflammatory drug is commonly used for pneumonia?
Flunixin meglumine (Banamine) for fever
Why should laminitis prevention be considered in pneumonia cases?
Endotoxemia from bacterial infection can trigger laminitis.
When is thoracocentesis or an indwelling chest tube indicated?
When large amounts of pleural fluid accumulate in pleuropneumonia.
What is the prognosis for pneumonia in horses?
Fair to good with aggressive treatment; worse for anaerobic infections and complicated cases.
What factors worsen prognosis in pleuropneumonia?
Development of laminitis
What is another name for Recurrent Airway Obstruction (RAO) in horses?
Heaves
What age group of horses is typically affected by RAO?
Middle-aged to older horses (>7-8 years old).
What are the primary clinical signs of RAO?
Increased respiratory effort (especially expiratory)
What environmental factors contribute to RAO?
Exposure to molds
What is the primary pathological change in RAO?
Bronchoconstriction and accumulation of mucus and neutrophils in the airways
How is RAO typically diagnosed?
Based on signalment
What bronchoalveolar lavage (BAL) fluid findings support a diagnosis of RAO?
Increased neutrophils; normally
What are Curshmann’s spirals
and what do they indicate?
Are thoracic radiographs useful in diagnosing RAO?
No
What is a key finding on arterial blood gas analysis in RAO?
Significant hypoxemia.
What is the primary treatment approach for RAO?
Environmental control and medications to manage inflammation and bronchoconstriction.
What environmental changes help manage RAO?
Avoid stabling
Which corticosteroids are used for RAO treatment?
Dexamethasone and prednisolone to reduce airway inflammation.
Which bronchodilators are used for RAO treatment?
Clenbuterol and albuterol to relieve bronchoconstriction.
How can RAO medications be administered?
Orally
What is the long-term prognosis for RAO?
Good with proper management
What is the causative agent of Strangles?
Streptococcus equi ssp. equi.
How is Strangles transmitted?
Inhalation or ingestion of respiratory secretions from infected horses.
What are key clinical signs of Strangles?
Fever
What severe complication can occur with repeated exposure to Strangles?
Purpura hemorrhagica (immune-mediated vasculitis).
What is the best diagnostic test for acute Strangles?
PCR or bacterial culture from nasal swab
What is the primary treatment for uncomplicated Strangles?
Supportive care; antibiotics (penicillin
How does Equine Herpesvirus (EHV) persist in horses?
Latent infection reactivates during stress
What are key clinical signs of EHV?
Fever
How is EHV diagnosed?
PCR from nasal swab.
How is EHV prevented?
Vaccination every 6 months in high-risk horses; pregnant mares vaccinated at 5
What is the primary mode of transmission for Equine Influenza A?
Inhalation of aerosolized virus from respiratory secretions.
What are clinical signs of Equine Influenza?
Fever
How is Equine Influenza diagnosed?
PCR from a nasal swab.
What is the primary treatment for Equine Influenza?
Supportive care
How can Equine Influenza be prevented?
Vaccination every 6 months for high-risk horses.
What is the suspected pathophysiology of EIPH?
High capillary pressure from high cardiac output causes capillary wall failure and bleeding into airways.
What is the most common clinical sign of EIPH?
Epistaxis during or after intense exercise.
How is EIPH diagnosed?
Endoscopy within 2 hours of exercise or bronchoalveolar lavage showing hemosiderophages.
What is the primary treatment for EIPH?
Furosemide (Lasix) administered before events to reduce pulmonary capillary pressure.
What is the pathogenesis of RAO?
Inflammation and bronchoconstriction caused by dust
What are the classic clinical signs of RAO?
Chronic cough
How is RAO definitively diagnosed?
Bronchoalveolar lavage cytology showing increased neutrophils.
What is the most important aspect of RAO management?
Environmental modification to reduce dust exposure.
What is the most common cause of primary sinusitis in horses?
Dental disease (infection of cheek teeth).
What are the key clinical signs of sinusitis?
Unilateral mucopurulent nasal discharge
How is sinusitis diagnosed?
Radiographs
What is the treatment for sinusitis?
Tooth extraction and sinus lavage.
What is the cause of laryngeal hemiparesis?
Idiopathic neuropathy of the left recurrent laryngeal nerve.
What are clinical signs of laryngeal hemiparesis?
Inspiratory noise (roaring) during exercise
How is laryngeal hemiparesis diagnosed?
Endoscopy of the upper airway.
What is the treatment for severe cases of laryngeal hemiparesis?
Laryngoplasty (‘tie-back’ surgery).
What age group is most affected by Rhodococcus equi?
Foals 1-3 months old.
What are clinical signs of Rhodococcus equi pneumonia?
Fever
How is Rhodococcus equi diagnosed?
Transtracheal wash cytology and culture
What is the treatment for Rhodococcus equi?
Rifampin and a macrolide (azithromycin
What is a major risk factor for pleuropneumonia?
Extended transportation with poor ventilation and tied heads.
What are clinical signs of pleuropneumonia?
Fever
How is pleuropneumonia diagnosed?
Thoracic ultrasound showing pleural effusion
What is the treatment for pleuropneumonia?
IV antibiotics
What condition can mimic a respiratory disease but is actually gastrointestinal?
Esophageal obstruction (choke).
What are clinical signs of choke?
Bilateral nasal discharge with feed material
How is choke diagnosed?
Failure to pass a nasogastric tube into the stomach.
What is the treatment for choke?
Sedation
What is the primary age range for foals affected by Rhodococcus equi?
Foals between 1-6 months of age.
How is Rhodococcus equi typically acquired?
Inhalation of the organism from a dusty environment.
What is the primary pathogen causing Rhodococcus equi infection?
Rhodococcus equi
Where does Rhodococcus equi replicate in infected foals?
Inside alveolar macrophages
What are the main clinical signs of Rhodococcus equi infection?
Intermittent fever
What are the common clinicopathologic abnormalities associated with Rhodococcus equi?
Neutrophilic leukocytosis and hyperfibrinogenemia.
What imaging findings are characteristic of Rhodococcus equi pneumonia?
Ultrasonographic evidence of pulmonary abscesses or characteristic radiographic pulmonary abscesses.
What is the gold standard for confirming Rhodococcus equi pneumonia?
Transtracheal wash with bacterial culture of Rhodococcus equi.
What is the treatment of choice for Rhodococcus equi pneumonia?
A macrolide (erythromycin
What supportive care measures are important in treating Rhodococcus equi?
NSAIDs for inflammation
What are some complications of Rhodococcus equi infection?
Abdominal abscessation
What neurologic complication can Rhodococcus equi cause?
Intervertebral abscess resulting in neurologic deficits such as weakness and ataxia.
What is the prognosis for foals diagnosed and treated early for Rhodococcus equi pneumonia?
Fair to good
How can Rhodococcus equi infection be prevented in breeding farms?
Administer hyperimmunized plasma early in life
Why is prophylactic macrolide use no longer recommended for Rhodococcus equi prevention?
Due to potential antibiotic resistance and questionable efficacy.
What routine monitoring can aid in early detection of Rhodococcus equi pneumonia?
Regular measurement of body temperature and respiratory rate
What is neonatal sepsis in foals?
A systemic disease caused by circulating microorganisms and their products.
At what age does neonatal sepsis typically occur in foals?
During the neonatal period
What are the primary routes of bacterial introduction in neonatal foals?
Inhalation
What is the most important factor in preventing neonatal sepsis?
Adequate passive transfer of maternal antibodies (IgG >800 mg/dL).
What is the most common bacterial isolate in neonatal foal sepsis?
E. coli.
What are other common bacterial causes of neonatal sepsis?
Streptococcus
What are the primary clinical signs of neonatal sepsis?
Weakness
What are key clinicopathologic abnormalities in neonatal sepsis?
Leukopenia
What diagnostic test definitively confirms neonatal sepsis?
Positive blood culture with bacterial identification and antimicrobial susceptibility testing.
What is a sepsis score in neonatal foals?
A point-based system that assigns values to abnormalities such as hypoglycemia
What are the main components of neonatal sepsis treatment?
Fluid therapy
What is a key complication of neonatal sepsis?
Septic arthritis
What is the prognosis for neonatal sepsis?
Guarded to good with early aggressive treatment; complications may worsen prognosis.
What is a major concern regarding neonatal sepsis treatment?
The cost of intensive care can be substantial for the client.
What is the causative agent of Strangles in horses?
Streptococcus equi.
What type of bacteria is Streptococcus equi?
Gram-positive
What age group is most commonly affected by Strangles?
Young horses (<2-5 years old).
How is Strangles transmitted?
Direct contact with purulent discharge from infected horses or contaminated equipment.
Where does Streptococcus equi establish infection in horses?
Pharyngeal mucosa and local lymph nodes (intermandibular and retropharyngeal).
Why is Strangles named as such?
Severe lymphadenopathy may occlude the airway
What is the incubation period for Strangles?
2-7 days.
What are the hallmark clinical signs of Strangles?
Fever
Which lymph nodes are most commonly affected in Strangles?
Intermandibular
What clinicopathologic abnormalities are associated with Strangles?
Neutrophilic leukocytosis and hyperfibrinogenemia.
How is Strangles diagnosed?
History
When is penicillin recommended in Strangles treatment?
If the horse is febrile without lymph node abscessation or has been recently exposed.
Why should penicillin be avoided once lymph node abscessation has occurred?
It may slow abscess maturation; treatment should focus on abscess drainage.
How should mature abscesses be managed?
Hot packing to promote maturation
What additional management strategies are needed for a Strangles outbreak?
Isolation
What is Bastard Strangles?
A form of internal abscessation affecting mesenteric or other lymph nodes.
What are the clinical signs of Bastard Strangles?
Chronic intermittent colic
What is Purpura Hemorrhagica?
Immune-mediated vasculitis resulting in limb and head edema
What complication occurs when purulent material collects in the guttural pouch?
Guttural Pouch Empyema
What are the consequences of septicemia in Strangles?
Occasional CNS involvement leading to encephalopathy and poor prognosis.
What is the prognosis for Strangles?
Good; most horses recover uneventfully and develop strong immunity
