LAM: Exam 1

Immunization protocols in horses

• What

  • Core: Tetanus, EEE, WEE, WNV, Rabies

    • tetanus toxoid and killed viruses

  • Risk-based: influenza, herpesvirus, strangles, EVA, VEE, botulism, rotavirus, PHF, anthrax

• When

  • Mares: re-immunized during 3rd trimester

  • Foals: colostral Ab, then vax 4-6, 7, 12m

  • Adults: priming series then annual boosters

    • 2-3 injections at 1m intervals

• Rxn: purpura hemorrhagica (Strep  equi), clostridial myonecrosis (bad technique)

  • Record lot/serial # + report to USDA/manufacturer

GI Parasite Control in Horses

• Major Types: ascarids (foals), strongyles (adults), tapeworms

• Tx: Use FEC & treat high-shedder adults, don't treat resistant individuals, pasture management

  • Nematodes: Benzimidazoles, ivermectin, moxidectin, pyrante

    • Adults: Treat all yearly w/ macrocyclic lactone for S  vulgaris

    • Foals: benzimadazoles q 60 d for first 1y for ascarids

    • Larvicidal deworming: high-dose benzimidazoles x multiple days

  • Tapeworm: Praziquantel & pyrantel

Fluid Loss in Horses

• MOA: water is drawn into intravascular space leading to hypovolemic shock

  • Normal: urine, respiration, skin evaporation

  • Pathologic: enteritis/colitis, hemorrhage, gradual reduced intake, effusions, sweating, rapid

• Cs: dry MM, concentrated/decreased urine, low GFR, tachycardia, vasoconstriction, poor perfusion, organ failure/death

• Tx: IV or Oral fluids

  • Adult: 50 ml/kg/d 

    • 25 L/day for 500 kg horse = 1 L/hr

  • Neonate: 100 ml/kg/d 

    • 5 L/day for 50 kg foal = 200 mL/hr

  • Shock: 40L/500kg horse

  • Ongoing: 60-120 L/day

Oral fluids in Horses

• Use: Minor fluid loss

• Equipt: NG tube

  • gravity safer than pump

• Rx: plain water, hypotonic electrolyte solution (Lg amounts)

• Dose: 5 L/500kg

IV fluid use in Horses

• Dose: fluid challenge principle (give ¼  deficit rapidly, reassess, repeat)

• Isotonic crystalloid fluids: 280-320 mOsm/L

  • BES (#1): alkalinizing, added Na, Ca, Cl, K, organic anions 

  • NS (0 9%): acidifying, use for hyperkalemia/Na depletion

• Colloids:

  • Hetastarch: rapid expansion, oncotic support, follow w/ isotonic crystalloids, limits edema, retained in IV space

  • Plasma: Ig, albumin, clotting factors, antitoxins, FPT, Hypoproteinemia

  • Whole blood: acute anemia (transfuse if PCV <20% in acute, <12% chronic; 6-8 L from Qa neg, un-sensitized gelding)

    • Monitor for HS Type I rxn

IV Catheters in Horses

• Site: Jugular, lateral thoracic & cephalic v 

  • Transverse facial artery: palpate arterial pulse, arterial blood gas collection

• Material: 14g, 5”

  • Short-term: Teflon, rigid, thrombogenic, crack

  • Long-term: polyurethane, pliable

• Rxn: phlebitis, thrombophlebitis, cellulitis

Sedative-analgesic drugs in Horses

• Alpha-2 agonists

  • Xylazine: short-acting, brief restraint, pre-anesthetic, first-line for colic

  • Detomidine: more potent, longer acting, CRI or oral gel, good for standing procedures 

• Butorphanol: Opioid of choice in horses, used w/ alpha-2s 

• Acepromazine: Tranquilizer, prolonged sedation,“drop penis” (risk of priapism in stallions)

Pain Management in Horses

• Colic pain: xylazine, butorphanol, flunixin

• MSK pain: NSAIDs (phenylbutazone)

• Peri-op pain: 

  • CRI: alpha-2, butorphanol, lidocaine, ketamine

  • Epidurals: lidocaine, alpha-2, morphine

NSAIDs in Horses

• MOA: inhibit COX → block prostaglandins/thromboxanes

• Rx: 

  • Flunixin meglumine: general, common

  • Phenylbutazone: ortho pain, cheap

  • Firocoxib (Equioxx): less ulcer risk

• Rxn: GI ulcers, Renal crest necrosis/interstitial nephritis, clostridial myonecrosis/injection rxn

Corticosteroids in Horses

• MOA: inhibit phospholipase A2 → shut down arachidonic acid cascade

• Uses: equine asthma, allergic skin dz, pemphigus foliaceus, uveitis, purpura hemorrhagica, IM polymyositis, IMHA, IBD, osteoarthritis (intra-articular)

  • Antiinflam + immunosuppression 

• Rx: prednisolone (oral), dexamethasone (oral/injectable), beclomethasone (inhaled), fluticasone (inhaled), triamcinolone (intra-articular)

• Rxn: laminitis, infection, impaired wound healing, cartilage degeneration, adrenal suppression

  • Avoid long acting types, use short acting

Empiric Guidelines for Antibiotic use in Horses

• Strep: penicillin, 1st-gen cephalosporins, ceftiofur

  • S  equi equi/zooepidemicus

• Anaerobes: penicillin

  • if resistant → oral metronidazole

• G - aerobic: gentamicyn 

• Rhodococcus equi: macrolide + rifampin (foals)

  • causes colitis in adults

• Clostridia: penicillin G, metronidazole

• Ehrlichial: Tetracyclines

• Potentiated sulfas: EPM, practical for alot

• Oral: potentiated sulfas, doxycycline

• Special combos: rifampin + sulfa/doxy 

  • chronic abscesses, off-label

Misc PE in Horses

• Airway Exam

  • Upper: obstruction, distress, noise, cough, discharge

    • Dt: endoscopy

    • Misc: alnar for increased airflow

  • Lower: faired nostrils, wheezing, discharge

    • Thoracic inlet: lower airway sounds auscultation

  • Normal Airway Cytology

    • Macrophages 40-70%

    • Lymphocytes 30-60%

    • Neutrophils  <5%

• Cardiac Exam

  • Valve areas: left ICSs 3,4,5; right ICS 4

  • HR: 28-44 BPM

    • high vagal tone

    • Resting 2^nd degree AV block is normal

Equine Herpes Viruses

• Et: EHV1-4, ubiquitous, latency

• Types:

  • Rhinopneumonitis: resp dz in weanlings/yearlings 2-5y (adults immune)

    • Cs: fever, malaise, serous nasal discharge, dry cough, lymphadenopathy

  • EHV-1 abortion: “abortion storms” at 7-11m (3rd trimester)

    • Cs: placental/fetal vasculitis, none pre-abortion or to mare

  • EHV-1 neuro 

    • Cs: acute ataxia, tetraparesis, sacral signs, spinal vasculitis 

• Dt: bld/nasal PCR/VI, fetal lesions, IHC post mortem

• Tx: rest, shelter, NSAIDs, antivirals, quarantine, report, vax (reduces shedding)

Equine Influenza

• Et: contagious, Type A H3N8, no carrier state 

  •  Invades resp epithelium, short incubation (1-3d)

• Cs: malaise, high fever, cough, serous nasal discharge, pneumonia, myocarditis, pericarditis, myositis, vasculitis, death

• Dt: PCR (#1), ELISA, VI, paired serology 

• Tx: Rest >21d, NSAIDs, good enviro, encourage feed/water intake, IM killed vax or MLV nasla vax

  • High-risk horses vax biannually

Streptococcus equi subsp  zooepidemicus

• Et: Opportunistic
  Cs: rhinitis, pharyngitis, sinusitis, pneumonia, peritonitis, abscesses, endometritis, keratitis, wound infections 

• Tx: penicillin

Streptococcus equi subsp  equi (Strangles)

• Et: Incubation 3-14d, M-protein (SeM) inhibits lysosomes, host adapted, Gram-positive, beta hemolytic

• Cs: purulent lymphadenitis of head & neck, airway obstruction, guttural pouch empyema, abscess, systemic metastasis, purpura hemorrhagica, fever, depression, anorexia, mucoid nasal discharge, vasculitis 

  • submandibular, medial retropharyngeal LN

• Dt: neutrophilia w/ L shift, high fibrinogen, PCR/culture (swabs, guttural pouch wash, pus), imaging (US/scope/Rads)

  • Evaluate guttural pouches 

• Tx: warm compresses, drainage, NSAIDs, Penicillin, quarantine, M-protein subunit/ Mod-live IN vax

  • Risk of purpura hemorrhagica post-vax, immunity not permanent

Nasal & Paranasal Disorders in Horses

• Epidermal inclusion cyst: nasal diverticulum, cosmetic; sx removal curative 

• Redundant alar folds:“floppy nostrils,” stertor, obstruction on inspiration; Dt mattress suture test; elective resection 

• Nasal septum deformities: congenital, trauma, rare, amyloidosis; may need resection 

• Choanal atresia: dev failure of nasopharyngeal perforation; neonatal resp distress

• Wry nose: lateral maxillary deviation, malocclusion, nasal occlusion; sx correction

• Progressive ethmoidal hematoma: benign mass, mild intermittent epistaxis; Dt w/ CT; Tx w/ sx bone flap, endoscopic laser ablation, formalin injection

Sinus Disorders in Horses

• Sinusitis

  • Et: 

    • Primary: bacti, viral, fungal

    • Secondary: dental disease (M1 tooth root abscess), trauma, ethmoidal hematoma, cysts, neoplasia 

  • Cs: unilateral mucopurulent discharge, malodor ( w/ tooth root infection), swelling/facial distortion 

  • Dt: endoscopy (nasomaxillary drainage), rads (fluid lines), CT, culture, cytology

  • Tx: drainage via trephination/lavage, antibiotics, tooth extraction, bone flap sx

• Paranasal sinus cyst

  • Et: Lg, multiloculated, congenital, slow-growing

  • Cs: facial deformity, mild discharge 

  • Dt: rads(cyst cavity), mucinous fluid on centesis

  • Tx: sx removal via bone flap

Pharynx & Larynx Developmental Conditions in Horses

• Cleft palate: milk in nostrils from birth; aspiration pneumonia; Dt w/ endoscopy; Tx w/ Sx

• Pharyngeal cysts: congenital; obstructive noise/choke; Tx w/ Sx removal 

• Hypoplastic/flaccid epiglottis: congenital or neuropathic; recurrent DDSP, resp nosise, epiglottis entrapment; Tx w/ epiglottic augmentation via Teflon injection

• 4th branchial arch defect: rare; resp noise, poor performance, cough, aspiration; Dt: “rostral displacement of palatopharyngeal arch”; No Tx

Dynamic Airway Obstruction in Horses

• Dynamic DDSP (soft palate)

  • Sig: 2-3y racehorses 

  • Cs: acute obstruction + “choking down ” at speed, 

  • Dt: treadmill/overground endoscopy 

  • Tx: fitness, tongue tie, myotenectomy, partial staphylectomy

• Left laryngeal hemiplegia (“roaring”)

  • Et: left recurrent laryngeal nerve failure, QHs/Tbs/Drafts

  • Cs: inspiratory noise + exercise intolerance 

  • Dt: Endoscopy 

  • Tx: prosthetic laryngoplasty “tieback” (Good return to full performance)

• Epiglottic entrapment

  • Et: Epiglottis enveloped by aryepiglottic fold

  • Cs: poor performance, noise, cough, DDSP, inflamed mucosa 

  •  Dt: endoscopy 

  • Tx: sx axial division of fold, anti-inflam sprays

• Dynamic pharyngeal collapse

  • Et: High insp neg pressures, narrow pharynx, neuropathy, fatigue, lymphoid hyperplasia, laryngeal hemiplegia, nasal obx

Inflammatory Pharynx & Larynx Conditions in Horses

• Pharyngeal lymphoid hyperplasia

  • Et: Normal in young horses, associated w/ immune dev

  • Cs: sore throat/cough, DDSP

  • Tx: rest, soft feeds, NSAIDs/steroids, throat sprays 

• Laryngitis/chondritis

  • Et: Persistent inflam, high-speed work, hemiplegia, epiglottic entrapment, coarse feeds 

  • Cs: obx, insp noise, dysphagia, aspiration, stenosis,  DDSP

  • Tx: rest, NSAIDs, antibiotics, partial arytenoidectomy, tracheostomy 

    • Poor prognosis for performance

• Pharyngeal cicatrix: Idiopathic inflam scarring, Texas pasture horses 

• Pharyngeal neuropathies: GP disease (mycosis), trauma, EPM, encephalopathy, toxins (lead, botulism), myopathies (HYPP, white muscle dz)

Guttural Pouch Disorders

• Tympany

  • Et: Air distension, foals, congenital or acquired

  • Cs: soft swelling throatlatch, resp distress 

  • Dt: endoscopy, rads

  • Tx: Sx fenestration of septum (unilateral), resection, decompression

    • Good prognosis 

• Mycosis

  • Et: Aspergillus, plaques near arteries/nerves 

  • Cs: aneurysm, rupture, epistaxis (fatal), neuropathy, aspiration, cough, dysphagia, Horners

  • Tx: stabilize hemorrhage, sx arterial occlusion (balloon/coil), antifungals

• Empyema

  • Et: strangle, carrier state

  • Cs: Purulent exudate, nasal discharge, fever, depression, airway obx

  •  Dt: endoscopy, culture/PCR 

  • Tx: lavage, antibiotics, Sx removal, Modified Whitehouse procedure (ventral drainage)

• Trauma/stylohyoid disease

  • Et: Avulsion of longus capitis/rectus capitis ventralis, fracture, Temporohyoid osteoarthropathy

  • Cs: hemorrhage, neuro signs, vestibular dx, facial paralysis

Conditions of the Trachea in Horses

• Et: infectious (EHV, strangles), trauma, stenosis, granulomas, FB, collapse (old ponies), neoplasia (SCC, melanoma)

• Tx: Tracheotomy

  • Incision: junction of upper 1/3 and lower 2/3 of neck, above sternomandibularis split 

    • Initial ventral midline incision

    • Horizontal incision of <50% annular ligament 

      • DO NOT Cut cartilage rings = chondroma/stenosis risk 

  • Healing: second intention

Bacterial Pneumonia

• Et: Strep  zooepidemicus (#1), Staph, E  coli, Klebsiella, Pasteurella, Actinobacillus, Pseudomonas, Bacteroides, Clostridium, Fusobacterium 

• Sig: performance horses, travel

• Cs: Fever, depression, anorexia, toxemia, dehydration, ventral lung sounds, shallow breathing, stilted gait, pain on percussion, purulent exudate, consolidation, necrosis  

• Dt: Inflam leukogram (↑ fibrinogen), US/rads w/ ventral consolidation, endoscopy/tracheal wash, thoracocentesis

• Tx: penicillin + gentamicin, metronidazole, NSAIDs, O₂, fluids, dust-free enviro, thoracotomy, chest tubes ± lavage

  • Aggressive, early intervention

Rhodococcus equi

• Et: G+ facutive intracellular, fecal/resp transmission, soil, vapA causes resistance

• Sig: foals 1-5m

• Cs: Hilar lymphadenitis, suppurative bronchopneumonia, intestinal signs, pulmonary parenchymal abscessation, synovial distention, septic arthritis 

• Dt: high fibrinogen/neutrophils/globulins), tracheal wash, culture 

• Tx: O₂, fluids, dust-free enviro, Azithromycin + rifampin, hyperimmune plasma 

  • Aggressive, early intervention

Fungal Pneumonia in Horses

• Et: antibiotic tx, Neutropenia, steroid tx

  • Opportunists: Aspergillus, Candida, Fusarium, Pneumocystis 

  • Primary: Histoplasma, Blastomyces, Coccidioides, Cryptococcus, Conidiobolus 

• Cs: Fever, depression, anorexia, toxemia, dehydration, abnormal/reduced lung sounds ventrally, shallow breathing, reluctance to walk, stilted gait, pain on percussion 

•  Dt: airway cytology, culture, biopsy; rads w/ patchy multifocal infiltrates, peripheral granulomas 

• Tx: amphotericin B, azoles, iodides

  • guarded prognosis

Aspiration Pneumonia in Horses

• Et: inhalation of saliva, feed, milk, oral meds (oil), choke, pharyngeal paresis, URT obstruction, cleft palate, bottle-fed neonates 

• Cs: Fever, depression, anorexia, toxemia, ventral lung sounds, shallow breathing, stilted gait, pain on percussion 

• Dt: Inflam leukogram, US/rads w/ ventral consolidation, endoscopy/tracheal wash w/ suppurative tracheal exudate, thoracocentesis

• Tx: penicillin + gentamicin, metronidazole, NSAIDs, O₂, fluids, dust-free enviro, chest tubes ± lavage

  • Aggressive, early intervention

Equine Asthma Spectrum

• Inflammatory Airway Disease

  • Et: dust, particulates, endotoxins, ammonia, air pollution, post-infectious inflam

  • Cs: no resp distress at rest, poor performance, exercise intolerance, cough, mild discharge 

  • Dt: performance issues, normal CBC, BAL, neutrophilic inflam

  • Tx: envirol control, steroids, bronchodialators 

• Recurrent Airway Obstruction (“Heaves”)

  • Et: Summer pasture, allergens, genetics

  • Sig: Older horses

  • Cs: cough, exercise intolerance, abnormal lung sounds, acute attacks, mucopurulent discharge, flared nostrils, expiratory effort (“heave line”)

  • Dt: normal temp/BW, BAL w/ non-septic neutrophilia, mucus plugs (Curschmann’s spirals), allergy testing

  • Tx: enviro control, steroids, bronchodialators 

Exercise-Induced Pulmonary Hemorrhage

• Et: hemorrhage from dorsal lungs during max exertion 

• Sig: racehorses

• Dt: Endoscopy w/in 45 min post-exertion, BAL cytology w/ hemosiderin-laden macrophages

• Tx: furosemide, nosebands

Heart Failure in horses 

• Et: poor myocardial  ventricular pumping efficiency

  • Myocardial injury/myopathy, Volume overload (valvular insufficiency, High afterload (pulmonary/systemic hypertension), Acute tachyarrhythmias (AF, VT)

• Types: 

  • Left: pulmonary hypertension/edema, poor systemic arterial circulation

    • Cs: weakness, exercise intolerance, cough, dyspnea, tachycardia, weak pulses

  • Right: systemic venous backup

    • Cs: jugular distention, edema

• Dt: murmurs, prerenal azotemia, high hepatic enzymes, high CVP, echo w/ chamber enlargement + poor function, rad w/ cardiomegaly + pulmonary edema

• Tx: Furosemide (diuretic), Digoxin (positive inotrope), Benazepril (ACE inhibitor)

Myocarditis in Horses

• Et: Influenza, bacti, parasitic, toxins #1 (Ionophores, venom, plants), IM, thromboembolic

• Cs: weakness, exercise intolerance, cough, dyspnea, tachycardia, weak pulses, fever

• Dt: High CK, high cardiac troponin, echo w/ poor contractility or abnormal motion, Stomach contents exam 

• Tx: Rest, furosemide, digoxin, benazepril, lidocaine, MgSO4, antibiotics, lavage, charcoal, mineral oil, smectite, Antivenom, Corticosteroids

  • Prognosis guarded

Cardiomyopathies in horses

• Adults: no primary cardiomyopathies; most secondary to myocarditis/valvular disease

• Foals: selenium deficiency (white muscle disease)

Acquired Valvular Disease in horses

• Et: degenerative change (#1), bacti endocarditis, ruptured chordae tendineae

  • Leads to regurgitation → volume overload → chamber enlargement → CHF

  • Mitral & aortic insufficiencies (#1)

• Sig: performance horses 

• Cs: #1 cause of pathologic murmurs, benign murmur, afib

  • AV valve insufficiency → systolic murmur 

  • Aortic insufficiency → diastolic murmur 

• Dt: echo (valve function, high L arterial pressure, chamber size, Doppler)

• Tx: retire from work

Bacterial Endocarditis in horses

• Et: bacti adhere to valves, rare

  • aortic > mitral > tricuspid > pulmonic

  • Strep equi zoo, Actinobacillus equuli

• Cs: intermittit fever, weight loss, murmur, inflam leukogram

• Dt: Neutrophilia, high fibrinogen, Echo (visualize lesion, regurg), Bld cultures

• Tx: Long-term IV antibiotics 

  • Prognosis poor

Pericarditis in horses

• Et: Inflam of pericardium, Actinobacillus, Strep zoo, influenza, EVA, AHS

  • Fibrinous or Effusive

• Cs: fever, depression, exercise intolerance, weakness, tachycardia, muffled heart sounds, weak pulses, circulatory collapse

• Dt: Echo (effusion), Pericardial tap, ECG w/ Low QRS amp

• Tx: Pericardial drainage + lavage, Antibiotics, Corticosteroids

  • Prognosis poor 

Congenital Heart Disease in Horses

• Et: VSD (#1), ASD, PDA, valve lesions, tetralogy of Fallot

• Sig: Arabians, STB, QH

• Cs: systolic murmur loudest on R, Growth stunting, lethargy, exercise intolerance, CHF, premature foal death

• Dt: echo/Doppler

• Tx: palliative only

Cardiac Arrhythmias in Horses

• Atrial fibrillation:

  • Et: #1 arrhythmia, high vagal tone, low K from GI dx, mitral insufficiency, atrial enlargement, CHF, low resting HR

  • Cs: exercise intolerance, poor performance, distress, collapse

    • asymptomatic at rest if benign 

  • Dt: ECG w/ no P waves, irregular R-R 

  • Tx: quinidine (oral), electrical cardioversion

    • Good prognosis 

• Ventricular tachycardia:

  • Et: systemic illness, endotoxemia, electrolyte disorders (↓ K+), myocarditis

  • Cs: syncope, resp distress, acute CHF, myocardial injury, HR >100 BPM

  • Tx: lidocaine (bolus + CRI), Mg sulfate

Hyperkolemia

• Et: Depresses impulse conduction

  • renal failure, post-renal obstruction, uroperitoneum, acidosis, severe rhabdomyolysis or hemolysis, over-supplementation, IV fluids

• Cs: atrial flutter, atrial standstill, asystole/cardia arrest

• Dt: K >6 mEq/dL, broad flat P, wide QRS, tall T

• Tx: dextrose, insulin, bicarbonate

Jugular thrombophlebitis in Horses

• Et: venipuncture, injections, catheterization, sepsis, endotoxemia

• Cs: thick vein, pain, swelling, venous congestion proximal, fever, facial swelling, pulmonary embolism, thrombophlebitis, occlusion

• Dt: inflam leukogram, high fibrinogen, US, culture

• Tx: remove catheter, warm compresses, anti-inflam, antibiotics, good catheter technique, asepsis, avoid bad veins, aspirin prophylaxis

Verminous arteritis

• Et: S vulgaris L4 larvae migrates in cranial mesenteric artery

• Cs: arteritis, stenosis, aneurysm, intestinal ischemia, infarction, colic, aortic root lesions, rupture, coronary artery migration,  thrombophlebitis

Aneurysm/rupture in Horses

• Et: mesenteric (hemoperitoneum), middle uterine artery (postpartum mares), internal carotid/maxillary (GP mycosis), aorta, sinus of Valsalva

• Cs: hemoperitoneum, hemopericardium, death

Arterial thrombosis in Horses

• Et: S vulgaris arteritis, idiopathic aorto-iliac thrombosis in athletes, sepsis, toxins

• Cs: sudden pain/lameness, cool limb, absent pulse, ischemic lameness

• Dt: rectal exam, US

• Tx: thrombolytics (TPA, streptokinase)

Acute bronchointerstitial pneumonia of foals

• Et: hot weather 

• Cs: high fever, respiratory distress, cyanosis, & high mortality

  • Sporadic 

• Dt: diffuse interstitial pattern, hypoxemia, hypercapnea

• Tx: O2, steroids

  • emergency

White Blood Cells in Horses

• Fibrinogen: coagulation/fibrin formation, acute phase reactant

  • High = active inflam, within 24h of infection, chronic bacti infections

• Serum amyloid A: same as fibrinogen

• Neutrophils: 

  • Stress: mature neutrophilia (no bands) + lymphopenia

  • Acute: high levels + left shift, high fibrinogen

  • Chronic: mature neutrophilia + hyperfibrinogenemia

  • Neutropenia: LPS (endotoxemia), GI dx, G- sepsis; left shift + toxic changes

    • Caused by margination

• Lymphocytes

  • Lymphopenia: Stress, steroids, acute infections

  • Lymphocytosis: Physiologic, lymphoid neoplasia

    • Lymphoblasts in peripheral blood = diagnostic

• Monocytes: high in chronic infection/convalescence, rarely neoplasia

• Eosinophils: Type HS, airway dz, parasites, eosinophilic enterocolitis, MEEDs

• Basophils: high w/ allergic dx

Leukogram Patterns

• Stress: mature neutrophilia + lymphopenia, normal fibrinogen, no bands

• Physiologic: mature neutrophilia + lymphocytosis, no left shift

• Inflam: Left shift, high fibrinogen

Lymphosarcoma

• Et: Malignant lymphoid neoplasia

  • Generalized, intestinal, mediastinal & cutaneous forms

• Cs: malabsorption, diarrhea, colic, organ dysfunction, fever, pleural effusion, resp issues, masses, anemia, inflam leukogram, atypical lymphoblasts, pancytopenia, 

  • LN enlargement not typical

• Dt: Blasts on bld smear (#1), LN aspirates, biopsy, BM aspirate

• Tx: Steroids, chemo, excision of cutaneous nodes 

  • Grave prognosis, Cutaneous better prognosis

Myeloproliferative Diseases in Horses

• Et: BM infiltrated w/ neoplastic granulocytic/monocytic cells, atypical cells in blood, leukemia, myelophthisis, pancytopenia

• Sig: young (~5 y)

• Cs: depression, fever, lymphadenopathy, splenomegaly, edema, mucosal hemorrhage

• Dt: CBC, BM aspirate

  • Prognosis is poor

Polycythemia

• Et: high PCV, RBC count, Hb

• Types:

  • Relative: fluid deficit or splenic contraction

  • Absolute: uncommon

    • Primary = polycythemia vera (rare, idiopathic, normal PO2, ↓ EPO)

    • Secondary appropriate = chronic hypoxia 

      • COPD, heart dx, high altitude

    • Secondary inappropriate = rare 

      • hepatic, renal, endocrine neoplasia

Red Blood Cells in Equines

• Unstable PCV: Lg splenic reserve

• Rouleaux formation: normal, must differentiate from autoagglutination

• Regeneration: not apparent on smear, need BM

• Howell-Jolly bodies: normal in sm #

• Mild plasma icterus: normal

Acute Hemorrhage in Horses

• Et: trauma, organ/artery rupture, coagulopathies, lung laceration, rib fracture, diaphragmatic tear, GP mycosis

• Cs: Pallor, tachycardia, tachypnea, hypovolemic shock, trembling, sweating, distress, white MM (>1/3 blood loss)

• Dt: low RBCs and plasma protein, US

• Tx: pressure bandage, nasal packing, suture/ligate, tie off vessels, crystalloid fluids, transfusions (PCV <20% w/i 12h or <12% 1-2d), autotransfussion 

  • Stop hemorrhage and volume expansion

Chronic Hemorrhage in Horses

• Et: GI bleeding, NSAID ulcers, platelet disorders, tumors, external parasites, urinary tract bleeding, clotting disorders

• Cs: animal stable unless stressed, adapted to hypoxemia 

• Dt: CBC, clotting studies, fecal occult blood, parasitology

• Tx: feed quality forage, avoid iron dextrans

Hemolytic Diseases in Horses

• Types: 

  • Intravascular: Free hemoglobin; Rapid; Schistocytes on smear

  • Extravascular: No gross hemoglobinemia/uria, gradual PCV drop

• Immune-mediated hemolytic anemia (IMHA)

  • Et: 

    • Primary: rare;  idiopathic autoimmune

    • Secondary: most common; infection, drugs lymphosarcoma, Alloimmune (neonatal isoerythrolysis, bad transfusions)

  • Cs: fever, jaundice, hemoglobinemia/uria, hyperbilirubinemia 

  • Dt: Acute anemia, normal TP, slide agglutination, Coombs, flow cytometry, 

  • Tx: Oxygen, transfusions, steroids (dex)

• Oxidative hemolysis (Heinz body anemia)

  • Et: oxidative injury, dry red maple, onions, Brassica, phenothiazine, pistaia trees

  • Cs: brown plasma, pigment nephropathy, heinz bodies, intravascular hemolysis, methemoglobinemia, Tachypnea, tachycardia, weakness

  • Tx: aggressive fluids, transfusion, supportive care

    • Prognosis is guarded

Neonatal Isoerythrolysis

• Et: Secondary IMHA, colostral Ab against foal’s RBC antigens

• Sig: Foals <1w, multiparous mare, mules 

• Cs: weakness, lethargy, pallor, tachypnea, tachycardia, anemia, jaundice, dehydration, metabolic acidosis, hypoglycemia, hyperbilirubinemia 

• Dt: Acute anemia, normal TP, jaundice foal agg, Coombs, flow cytometry, test mares for Aa/Qa, mare serum vs stallion RBCs, colostrum screen

• Tx: Rest, correct fluids/electrolytes/glucose, transfusion, donor colostrum

Coagulation disorders in horses

• Thrombocytopenia

  • Et: blood loss, destruction, decreased production, high consumption

    • Idiopath, BM suppression, potentiated sulfas, IMTP, hemmorage

  • Cs: petechiae, epistaxis, GI bleeding, mucosal hemorrhage 

    • Spontaneous bleeding if platelets <30,000/µL

• DIC:

  • Et: Triggered by endotoxemia, SIRS, G- sepsis, burns, trama, neoplasia

    • Generalized activation of the coagulation cascade

    • consumption of platelets, factors, fibrinogen

  • Cs: petechiae, ecchymoses, microvascular thrombosis, hemorrhagic diathesis

  • Dt: low platelets/fibrogen, high PT/APTT/FDPs

• Hepatic failure: 

  • Et: decreased clotting factors

  • Tx: frozen plasma 

• Rodentaside/sweetcover:

  • Et: decreased clotting factors

  • Cs: epistaxis, hematomas, hemarthroses, bleeding, hyphema, anemia

  • Dt: prolonged PT/APTT, normal platlet count, no FDP

  • Tx: Vit K

• Genetic (rare): Hemophillia A (TB/QH/STB/Arab), vWB dx, Prekallikrein deficiency (draft/mini)

• Production issues: chronic dx, BM suppression, sulfas, Erythropoietin deficiency, GI bleeding, iron seq

Vasculitis

• Et: Inflam of sm vessels, immune mediated, infectious, Purpura Hemorrhagica

  • Vascular and hemostatic 

• Cs: pitting edema, mucosal hemorrhages, petechiation, serosal hemorrhages, jaundice, thrombocytopenia, anemia, fever

• Tx: report if EVA/EIA/prioplasmosis

Purpura Hemorrhagica

• Et: IM, post-Strep equi equi infection or vax

  • leukocytoclastic vasculitis, fibrinoid necrosis

• Cs: limb/ventral/facial edema, petechiation, urticaria, fever, necrosis/sloughing, myocarditis, laminitis, infarctive myopathy

  • multisystem involvement

• Dt: history of strangles/vax, high SeM titers for Strep, high globulins 

• Tx: drain abscesses, antibiotics, immune suppression, hydrotherapy, eliminate Ag, compression

  • Prognosis is fair-good; relapses possible

Equine Viral Arteritis

• Et: RNA virus, resp & venereal (semen) transmission

  • Cell associated viremia, accessory sex glands, placenta 

• Cs: fever, edema, urticaria, resp dx, nasal discharge, lacrimation, icterus, leukopenia; abortions (3-10 m gestation), vasculitis 

  • Subclinical common

• Dt: PCR/virus isolation, serology (bld, nasal, fetal)

• Tx: MLV vax (stallions before breeding, annual boosters), test semen, reportable

Equine Infectious Anemia (“Swamp Fever”)

• Et: Retrovirus; transmitted by biting flies, iatrogenic, in utero, colostrum

  • Unregulated QH racing in North america 

• Cs:

  • Acute (30 d): fever, thrombocytopenia, lethargy, vasculitis, high viremia

  • Chronic: ill-thrift, recurrent fever, anemia, thrombocytopenia, jaundice, low viremia

  • Carrier (#1): lifelong infection, no signs

• Dt: Coggin’s test (AGID gold standard), ELISA

• Tx: permanent quarantine, test before travel, euthanasia, report, persistent infection

Equine Piroplasmosis

• Et: Protozoal RBC parasites (Babesia caballi, Theileria equi), Dermacentor ticks 

  • Endemic South america, europe, mediterranean

  • Unregulated QH racing in North america  

• Cs: hemolytic anemia, fever, icterus, edema

  • Permanent subclinical 

• Dt: blood smear (parasites in RBCs), cELISA/CF for carriers

• Tx: imidocarb, report, quarantine

Equine Granulocytic Anaplasmosis

• Et: Anaplasma phagocytophilum, tick-borne, Ixodes, North america

• Cs: fever, depression, ataxia, edema, petechiation, icterus, anemia, thrombocytopenia, leukopenia, vasculitis

  • worse in adults

• Dt: morulae in neutrophils on smear, PCR, serology

• Tx: tetracyclines

Corynebacterium pseudotuberculosis (Pigeon Fever)

• Et: Gram+ facultative anaerobe, intracellular, soil organism, wounds, insects

  • Inhabits macrophages 

• Sig: arid N America, late summer/fall, post drought + rain

• Cs: classic pectoral abscesses (#1), external/internal abscesses, ulcerative/purulent lymphangitis, cellulitis, severe limb swelling

  • 3 forms: External/Internal abscesses Ulcerative lymphangitis

• Dt: Culture, inflam leukogram, high fibrinogen/globulins, SHI titer, US

• Tx: allow maturation, lance/drain, antibiotics, Sx

  • Antibiotics before drainage = delays healing

  • Internal worse prog than external