Farm animal CV disease

Question 1

Most common cause of pericarditis - cattle?

Answer 1

Bacterial

Question 2

Most common cause of pericarditis - horses?

Answer 2

Idiopathic

Question 3

Define septic pericarditis

Answer 3

Bacteria but from a different original location to the heart

Question 4

Outline the different causes of pericardial disease -5

Answer 4

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.

Question 5

Pathogenesis - traumatic pericarditis

Answer 5

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.

Question 6

Clinical signs - traumatic peridcarditis

Answer 6

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

Question 7

Describe the Williams test

Answer 7

Listen to the rumen, when this contracts the animal grunts due to pain (positive result)

Question 8

Describe the Bar Test

Answer 8

Put metal bar under cow and lift up against xiphoid process - positive if there is a painful reaction to this.

Question 9

Describe the Pinch Test

Answer 9

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.

Question 10

Diagnosis - Traumatic pericarditis

Answer 10

Mostly done on clinical exam (finances)
Radiography - high value animals
Ultrasound - most farm vets
Pericardiocentesis (only with ultrasound!)

Question 11

Treatment - traumatic pericarditis

Answer 11

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.

Question 12

Why shouldn’t you ever use >1 ruminal bolus?

Answer 12

They repel each other!

Question 13

Outline lymphosarcoma in cattle

Answer 13

Animals positive for bovine leukaemia virus (BLV)

Lymphoma masses may develop in right atrial wall or pericardium.

Question 14

Causes of pericarditis in pigs? 2

Effects?

Answer 14

Haemophilus parasuis (Glasser's disease) - commonest
Strep. suis

EFFECTS: fever, depression, fibrinos poly-serositis (in joints), effusions (CNS, pleura, peritoneum and synovia)

Question 15

Pathogenesis - pericardial effusions in horses

Answer 15

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.

Question 16

Clinical signs - pericardial effusions - horses - 5

Answer 16

• 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)

Question 17

Diagnosis - pericardial effusions - horses - 3

Answer 17

ECHO: fluid +/- fibrin in pericardial sac, compression of cardiac chambers
ECG: small complexes, main differential is obesity
CYTOLOGY OF PERICARDIAL FLUID

Question 18

Treatment - pericardial effusions - horses

Answer 18

Repeated pericardial drainage and lavage +/- ABs esp if RA is collapsing (i.e. cardiac tamponade)

Question 19

Prognosis- pericardial effusions - horses

Answer 19

Good - if Tx is early and aggressive

Constrictive disease may occur in chronic cases - poor

Question 20

Outline 2 features of bacterial endocarditis

Answer 20

Usually secondary to bacteraemia (ruminants/FAs common. Horses - less common) and can involve any of the valve.s.

Question 21

Site of infection of bacterial endocarditis - cattle versus horses

Answer 21

RUMINANTS/OTHER FAs = liver abscess, traumatic reticulitis, metritis, mastitis, navel abscess, joint ill
HORSES: site of sepsis often not identified, septic jugular thrombophlebitis

Question 22

Diagnosis - bacterial endocarditis

Answer 22

CS: CHF with murmur, fever, cardiac murmur, tachycardia, tachypnoea
LAB: hyperfibrinogenaemia, anaemia and leucocytosis
BLOOD: repeat 3*, sterile procedure

Question 23

Why is prognosis of bacterial endocarditis poor?

Answer 23

(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).

Question 24

Name 2 cardiopulmonary diseases

Answer 24

Cor pulmonale

EIPH

Question 25

What is cor pulmonale secondary to? | What does it lead to? 3

Answer 25

Secondary to pulmonary hypertension and leads to hypertrophy, dilation and ultimately failure of the RV

Question 26

Causes of cor pulmonale - 3

Answer 26

Chronic pulmonary disease Pulmonary vascular disease High altitude (causes vasoconstriction, aka 'brisket disease' or 'high altitude disease')

Question 27

Clinical signs - cor pulmonale

Answer 27

Clinical signs of right-sided HF: - SC oedema - Jugular venous distension and pulsations - Dyspnoea and tachypnoea - Tachycardia and cardiac murmur

Question 28

Why is the prognosis of cor pulmonale usually hopeless?

Answer 28

Due to underlying chronic, irreparable lung pathology - if high altitude disease move to lower pastures

Question 29

Define EIPH

Answer 29

Exercise-induced pulmonary haemorrhage

Question 30

Pathogenesis - EIPH

Answer 30

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.

Question 31

What is the main problem in EIPH leading to pathology?

Answer 31

Capillary stress failure

Question 32

What is capillary stress failure in EIPH?

Answer 32

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.

Question 33

T/F: even with thin-walled capillaries, normal TBs become hypoxic and hypercapnic during exercise

Answer 33

True

Question 34

By how much do CO and pulmonary vascular pressures increase during exercise?

Answer 34

5-10 fold.

Question 35

What is the pressure failure point of equine pulmonary capillaries?

Answer 35

75-100mmHg (these are similar to the pressures generated during exercise)

Question 36

Why does EIPH originate in the caudodorsal lung lobes of horses?

Answer 36

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.

Question 37

Predisposing conditions - EIPH - 3

Answer 37

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).

Question 38

Clinical significance - EIPH | What is your job as the vet in cases of EIPH?

Answer 38

VARYING OPINIONS: 60-705 horses are endoscopically positive post-racing S JOB: rule out underlying respiratory or cardiac disease.

Question 39

Clinical signs - EIPH

Answer 39

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.

Question 40

Diagnosis - EIPH

Answer 40

CLINICAL EVIDENCE ENDOSCOPY BALV - RBCs and haemosiderophages RADIOGRAPHY - localised regions of interstitial opacity in caudodorsal lung fields but this is non-specific.

Question 41

What are haemosiderophages?

Answer 41

WBCs that 'eat' blood pigments

Question 42

Case management - EIPH - 2

Answer 42

- 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).

Question 43

Medication - EIPH

Answer 43

* **FEI guidelines - horses cannot be competed in the UK when on drugs *** - Furosemide - Diuretic and vasodilator - Vasodilators (NO, arginine, ACEI)

Question 44

Prognosis - EIPH

Answer 44

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.