Farm animal CV disease Flashcards
Most common cause of pericarditis - cattle?
Bacterial
Most common cause of pericarditis - horses?
Idiopathic
Define septic pericarditis
Bacteria but from a different original location to the heart
Outline the different causes of pericardial disease -5
SEPTIC PERICARDITIS - traumatic and embolic causes, commonest form in cattle
IDIOPATHIC (SPONTANEOUS AND NON-SEPTIC) - pericardial effusions, most common form in horses
PRIMARY BACTERIAL PERICARDITIS - most common form in pigs
NEOPLASTIC - uncommon in LAs
VIRAL - uncommon in LAs.
Pathogenesis - traumatic pericarditis
Ingestion of wires/nails –> forced through wall of reticulm into peritoneal cavity, through diaphragm into pericardial sac –> septic fluid, fibrous ‘cheesy’ exudate, adhesions (bread and butter pudding), gas within pericardial sac. May also have reticular abscesses, liver abscess, peritonitis.
Clinical signs - traumatic peridcarditis
EARLY: 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: right -sided (Constrictive) HF, venous congestion, peripheral oedema
CVS EXAM: tachycardia, muffled heart sounds, +/- splashing washing machine murmurs, venous distension (enlarged milk vein), raised jugular pulse, weak pulse
Describe the Williams test
Listen to the rumen, when this contracts the animal grunts due to pain (positive result)
Describe the Bar Test
Put metal bar under cow and lift up against xiphoid process - positive if there is a painful reaction to this.
Describe the Pinch Test
The whithers are pinched and an audible groan and/or sound in the trachea is heard if the animal is in pain and this is a positive result.
Diagnosis - Traumatic pericarditis
Mostly done on clinical exam (finances)
Radiography - high value animals
Ultrasound - most farm vets
Pericardiocentesis (only with ultrasound!)
Treatment - traumatic pericarditis
Must animals culled
Treatment = surgical in expensive animals: remove via a rumenotomy OR marsupialise the pericardial sac, debride and lavage via a rib thoracotomy approach.
Why shouldn’t you ever use >1 ruminal bolus?
They repel each other!
Outline lymphosarcoma in cattle
Animals positive for bovine leukaemia virus (BLV)
Lymphoma masses may develop in right atrial wall or pericardium.
Causes of pericarditis in pigs? 2
Effects?
Haemophilus parasuis (Glasser's disease) - commonest Strep. suis
EFFECTS: fever, depression, fibrinos poly-serositis (in joints), effusions (CNS, pleura, peritoneum and synovia)
Pathogenesis - pericardial effusions in horses
Majority are idiopathic
Minority are pericarditis (EVA, EIV, Strep. pneumoniae, E.coli, Actinobacillus equili, tend to develop fibrinous effusion)
Penicillin is the drug of choice initially.
Clinical signs - pericardial effusions - horses - 5
- Venous distension
- Ventral oedema
- Muffled heart sounds
- Pericardial friction rubs (squeaky, easy to miss)
- Pleural effusion (dyspnoea, dullness on percussion, smaller lung field on auscultation)
Diagnosis - pericardial effusions - horses - 3
ECHO: fluid +/- fibrin in pericardial sac, compression of cardiac chambers
ECG: small complexes, main differential is obesity
CYTOLOGY OF PERICARDIAL FLUID
Treatment - pericardial effusions - horses
Repeated pericardial drainage and lavage +/- ABs esp if RA is collapsing (i.e. cardiac tamponade)
Prognosis- pericardial effusions - horses
Good - if Tx is early and aggressive
Constrictive disease may occur in chronic cases - poor
Outline 2 features of bacterial endocarditis
Usually secondary to bacteraemia (ruminants/FAs common. Horses - less common) and can involve any of the valve.s.
Site of infection of bacterial endocarditis - cattle versus horses
RUMINANTS/OTHER FAs = liver abscess, traumatic reticulitis, metritis, mastitis, navel abscess, joint ill
HORSES: site of sepsis often not identified, septic jugular thrombophlebitis
Diagnosis - bacterial endocarditis
CS: CHF with murmur, fever, cardiac murmur, tachycardia, tachypnoea
LAB: hyperfibrinogenaemia, anaemia and leucocytosis
BLOOD: repeat 3*, sterile procedure
Why is prognosis of bacterial endocarditis poor?
(even after bacteriologic cure) due to permanent structural damage to valve, in horses, some right-sided lesions may have return of performance.
ALSO, SEPTIC EMBOLI - lungs (from right hear), kidneys/joints (from left heart).
Name 2 cardiopulmonary diseases
Cor pulmonale
EIPH
What is cor pulmonale secondary to?
What does it lead to? 3
Secondary to pulmonary hypertension and leads to hypertrophy, dilation and ultimately failure of the RV
Causes of cor pulmonale - 3
Chronic pulmonary disease
Pulmonary vascular disease
High altitude (causes vasoconstriction, aka ‘brisket disease’ or ‘high altitude disease’)
Clinical signs - cor pulmonale
Clinical signs of right-sided HF:
- SC oedema
- Jugular venous distension and pulsations
- Dyspnoea and tachypnoea
- Tachycardia and cardiac murmur
Why is the prognosis of cor pulmonale usually hopeless?
Due to underlying chronic, irreparable lung pathology - if high altitude disease move to lower pastures
Define EIPH
Exercise-induced pulmonary haemorrhage
Pathogenesis - EIPH
Pulmonary haemorrhage during strenuous exercise. Volume varies (local pulmonary, traces of tracheal blood, copious tracheal blood, epistaxis)
Horses, dogs and humans
Haemorrhage is from pulmonary rather than bronchial vessels
Horses - haemorrhage typically originates in the caudodorsal lung lobes.
What is the main problem in EIPH leading to pathology?
Capillary stress failure
What is capillary stress failure in EIPH?
Mechanical pressures (breathing, CV and locomotor) generated in pulmonary capillaries during exercise exceed their stress failure point.
Pulmonary capillaries are an inevitable anatomical weak point because they are thin-walled.
Haemorrhage causes local inflammation which further increases regional resistance and pressures.
T/F: even with thin-walled capillaries, normal TBs become hypoxic and hypercapnic during exercise
True
By how much do CO and pulmonary vascular pressures increase during exercise?
5-10 fold.
What is the pressure failure point of equine pulmonary capillaries?
75-100mmHg (these are similar to the pressures generated during exercise)
Why does EIPH originate in the caudodorsal lung lobes of horses?
HIGH BF - lower intrinsic vascular resistance
DIAPRAGMATIC DISPLACEMENT - causes transient falls in alveolar pressure. Lower alveolar pressure leads to greater transmural pressure: failure.
Mechanical forces transmitted to lung are greatest in caudodorsal lobes.
Predisposing conditions - EIPH - 3
YOUNG TBs - this is a physiological response to exercise
AGE - prevalence increases with age
CONDITIONS WHICH INCREASE PULMONARY VASCULAR RESISTANCE: lower resp. tract disease (RAO), upper resp. tract obstruction (RLN), cardiac disease (AF, MVD).
Clinical significance - EIPH
What is your job as the vet in cases of EIPH?
VARYING OPINIONS:
60-705 horses are endoscopically positive post-racing
S JOB: rule out underlying respiratory or cardiac disease.
Clinical signs - EIPH
Depends on volume of haemorrhage and whether underlying disease is present:
often no CS OR poor performance, sudden onset exercise limitation, swallowing after exercise, epistaxis, other signs of URT, LRT or cardiac disease.
Diagnosis - EIPH
CLINICAL EVIDENCE
ENDOSCOPY
BALV - RBCs and haemosiderophages
RADIOGRAPHY - localised regions of interstitial opacity in caudodorsal lung fields but this is non-specific.
What are haemosiderophages?
WBCs that ‘eat’ blood pigments
Case management - EIPH - 2
- ID and treat predisposing URT, LRT or cardiac disease
- BREAK the haemorrhage - inflammation cycle (modify training to reduce episodes, dust-free environment, furosemide to reduce pulmonary capillary pressure).
Medication - EIPH
- **FEI guidelines - horses cannot be competed in the UK when on drugs ***
- Furosemide - Diuretic and vasodilator
- Vasodilators (NO, arginine, ACEI)
Prognosis - EIPH
GOOD TO FAIR: if spontaneous and having minimal impact on performance OR if associated with respiratory infection OR other predisposing cause that can be identified and treated.
POOR: for idiopathic bleeders with performance limitations.
