Large Animal Cardiovascular Disease, Royal Veterinary College University of London

Learning Objectives

Students should be able to:

• explain the pathogenesis of pericardial disease in large animals
• be able to advise on the prevention of pericardial disease in cattle
• discuss the pathogenesis of bacterial endocarditis in large animals and outline treatment options and prognosis
• understand the pathogenesis of cor pulmonale in cattle
• understand, diagnose and treat thrombophlebitis
• understand, diagnose and treat exercise induced pulmonary haemorrhage in horses

Approach to the Cardiac Patient

• Often non-specific clinical complaint
  • Decreased muscle mass or milk production
  • Increased respiratory rate/effort
  • Decreased exercise tolerance
• Crucial information
  • Signalment
  • Onset, duration and progression of chief complaint
  • Diet and supplements
  • Housing environment
  • Reproductive status
  • Deworming programme
  • History of illness
  • Presence of other animals with similar signs

Physical Exam Findings

• Mucous membranes
  • Pale - anaemia, decreased cardiac output
  • Hyperaemic - secondary to sepsis, peripheral vasodilation, hyperdynamic output
• Capillary refill time
  • Prolonged - diminished cardiac output and/or shock
• Jugular fill and pulses
  • Pulses > lower 1/3 neck are abnormal
  • Distension and increased pulsation - right heart abnormalities/arrythmias
• Ventral (brisket) oedema
  • Common sign heart failure (R>L)
• Arterial pulse rate and pressure
  • Hyperkinetic pulses - increase systolic pressure, decreased diastolic pressure or both
  • Hypokinetic pulses - diminution of cardiac output, systemic vasodilation in shock
• Auscultation
  • Can hear 3 to 4 sounds normally
  • Muffled sounds - pericardial/pleural effusion
  • 'Washing-machine' murmur' - gas/fluid/fibrin within pericardium

Normal Heart Rate Range (bpm)

Animal Adult Calf Adult Lamb Adult Kid Adult Cria

Cattle Sheep Goat Llama

Normal heart rate range (bpm) 60-120 40-80 100-140 120-160 70-110 120-160 60-90 80-120

Mark, W.H. (2017). Ruminant and Camelid Cardiology. In Cardiology for Veterinary Technicians and Nurses, H.E. Durham (Ed)

Pericardial Disease

Pericarditis

• Inflammation of the pericardium
  • Results in fluid/exudate accumulation between visceral and parietal pericardium
• Causes:
  • Trauma
    • Penetration ingested objects or external wound
    • Haematogenous spread (septicaemia)
  • Extension of lung/pleural infection
  • Viral infections
    • Eg. Influenza
  • Neoplasia
  • Mare reproductive loss syndrome (MRLS)
  • Actinobacillus
  • Idiopathic

Fibrous pericardium Myocardium Parietal layer of serous pericardium Pericardial cavity Endocardium Epicardium (visceral layer of serous pericardium)

https://microbenotes.com/pericardium-structure-functions/

Traumatic Reticuloperitonitis (TRP) and Pericarditis

TRP results from penetration of reticulum by a foreign body

• Possible outcomes of ingested object:
  1. Attachment to previously administered magnet
  2. Penetration of reticular wall without entering peritoneal cavity causing focal reticulitis and mild clinical disease
  3. Perforation of reticular wall and entrance to peritoneal cavity causing acute localised TRP
  4. Perforation of reticular wall and entrance to peritoneal/thoracic cavity resulting in pericarditis, myocarditis, abscessation, vagal indigestion or other secondary disease

Traumatic Pericarditis: Clinical Signs

• Early signs
  • Fever, anorexia, depression
  • cranial abdominal, reticular and thoracic pain:
    • stand with elbows abducted
    • reluctant to move or grunt/groan when moving
    • positive Williams test, 'Bar test' and 'Pinch test'
• Later signs:
  • right-sided (constrictive) heart failure
  • venous congestion, peripheral oedema

Traumatic Pericarditis: Cardiovascular Clinical Signs

• Tachycardia
• Muffled heart sounds
• + splashing "washing machine" murmurs
• venous distension
• raised jug pulse
• weak pulses

A B 10 10 RV RA LV LA PE Fluid in pericardial sac leads to cardiac compression

• when pressure in sac exceeds that of the heart:
  • Reduced ventricular filling and diastolic dysfunction
  • Main consequence on 'lower pressure' chamber - ie. right-side
  • Clinical signs of right-sided congestive heart failure

Journal of the American Veterinary Medical Association 241, 3; 10.2460/javma.241.3.315

Traumatic Pericarditis: Diagnosis and Treatment

• Bloodwork
  • suggestive but absence of abnormalities doesn't rule out
• Radiography
  • Limited to referral practices
  • Useful to identify foreign body
• Ultrasound
  • Detecting abnormal reticular motility
  • Pericardial effusion

Treatment

• Removing foreign body or preventing further trauma/penetration (magnet)
• Thoracotomy and marsupialisation of pericardial sac with lavage and debridement

Neoplasia

• Cardiac neoplasia uncommon
• Can be primary or secondary from adjacent structures
  • lung, pleural, lymph nodes, diaphragm
• Most common primary tumour is lymphosarcoma
  • Mesotheliomas, melanomas, lipomas, fibrosarcoma and adenocarcinomas, haemangiosarcoma also occur

11:34:07 1 LOGIQ E9 - 10- - 20- 30-

Clinical Signs of Neoplasia

• Non-specific
  • Depend on the site of the tumor and other sites of tumor manifestation
  • Anorexia, depression, weight loss, fever
• Pericardial involvement
  • Tachycardia, pain, jugular distension, peripheral edema, weak pulses
• Myocardial involvement
  • Tachycardia, cardiac arrhythmias, cardiac murmur
  • CHF: peripheral edema, ascites, diarrhea

Lymphosarcoma in Cattle

• Bovine leukaemia virus (BLV) NOTIFIABLE IN THE UK CURRENTLY ERADICATED PRESENT IN THE USA AND CANADA
  • More than 50% cattle in parts of USA positive for BLV but only 1-5% develop lymphosarcoma
  • Cardiac involvement common with adult/enzootic form
  • Commonly in cattle > 4yo
• Lymphoma - predilection for right atrial myocardium
  • RAP increases, jugular distension
  • Can also occur in RV myocardium
  • LA/LV myocardium rarer
• Pericardium
  • Pericardial effusion (often hemorrhagic)
  • Right sided heart failure
  • Cytology reveals neoplastic cells

Smith, Large Animal Internal Medicine

Pericarditis in Pigs

• Haemophilus/Glaesserella parasuis (Glasser's disease), Strep. suis
  • fever, depression, fibrinous poly serositis, effusions in CNS, pleura, peritoneum, and synovia

3 3 3 11

Pericardial Effusions in Horses: Aetiology and Pathology

• the majority of cases are idiopathic pericardial effusions
• minority are infectious pericarditis
  • equine viral arteritis (notifiable), equine influenza
  • Strep. pneumoniae, E.coli, Actinobacillus equuli
  • tend to develop fibrinous effusion

Table 1 Potential etiologies of pericardial disease (effusion, pericarditis, mass lesions) in horses Etiology Reference Viral Equine herpes Virus-1 8 Bacterial Actinobacillus spp. - has been associated with mare reproductive loss syndrome 8,13,15 Pasteurella spp. 8 Streptococcus spp. 16 Mycoplasma felis 17 Clostridium perfringens 18 19 Rhodococcus equi Other reported results from pericardial culture: Escherichia coli, Staphylococcus aureus, Pseudomonas spp., Acinetobacter, Enterococcus faecalis, fungi Neoplasia 20 Lymphoma (most common), mesothelioma, hemangiosarcoma Mass lesion (intra- or extrapericardial) compressing the heart Pericardial effusion following systemic neoplastic disease 21-23 Trauma: external, foreign body from gastrointestinal tract or iatrogenic during bone marrow aspiration Pericardial effusion associated with myocardial disease (see Box 1) or congestive heart failure Immune-mediated (or virus-induced) - occasionally associated with vasculitis and hemolytic anemia 8 Idiopathic - often associated with respiratory disease 8,24 Hemopericardium following rib fracture or aortic root rupture 13,14 Corynebacterium pseudotuberculosis

Pericardial Effusions in Horses: Clinical Signs

• venous distension
• ventral oedema
• muffled heart sounds
• pericardial friction rubs (difficult to hear/easy to miss)
• pleural effusion
  • dyspnoea, dullness on percussion, smaller lung field on auscultation

Pericardial Effusions in Horses: Diagnosis

• Echocardiography
  • fluid ± fibrin in pericardial sac
  • compression of cardiac chambers
• Electrocardiogra
  • small complexes
  • Low voltage complexes
  • Distance?
  • main differential is obesity
• Cytology of pericardial fluid

20 Feb 2000 2D: Abdomen 3: 0.4

Pericardial Effusions in Horses: Treatment and Prognosis

Treatment

• repeated pericardial drainage and lavage ± antibiotics, esp if the right atrium is collapsing (i.e. cardiac tamponade)

Prognosis

• good provided treatment is early and aggressive
• constrictive disease may occur in chronic cases

Cor Pulmonale

• Secondary to pulmonary hypertension
  • leads to RV hypertrophy, dilation or failure.
• Causes
  • High-mountain disease / high-altitude disease / brisket disease
  • Hypoxic vasoconstriction from high-altitude dwelling
  • Certain cattle more genetically susceptible
  • Chronic Pulmonary disease
  • Bronchopneumonia or lungworm infection
  • Equine - chronic/severe asthma

Cor Pulmonale: Clinical Signs

• Clinical signs: Subcutaneous edema of the brisket, ventral thorax, submandibular area and limbs
• Lethargy, weakness, bulging eyes, diarrhea, collapse and death may occur
• Jugular pulses/distension may be present
• Dyspnoea and tachypnoea frequent
• Split S2
• Pulmonary hypertension seperates closing of Aortic and Pulmonic valves

Murmur

• Tricuspid regurg or pulmonary ejection

Cor Pulmonale - Treatment and Prevention

• Prognosis usually hopeless because of underlying chronic, irreparable lung pathology
• if high altitude disease, move to lower pastures

Vascular Disease

• Aneurysms:
  • Vascular dilations - weakening of outer elastic coat of blood vessels
  • Causes: trauma, sepsis, parasites, ageing, degenerative vascular disease
  • Friesians - underlying connective tissues disorder
• Embolism:
  • Foreign material carried in bloodstream
  • Frequently arise from thrombus but can include catheters and other foreign bodies
• Thrombosis
  • Formation of clot that obstructs blood flow in the circulatory system
  • Trauma, venous stasis, catheterization, needle penetration, thrombogenic solutions, bacterial contamination
  • Secondary thrombosis: cellulitis, lymphangitis