Systemic Hypertension, Pericardial Effusion, HW Disease Flashcards
What two factors determine MAP?
CO (SV & HR) and SVR
What BP value is considered hypertensive?
Systolic > 160 mm Hg
What BP value is dangerous and can lead to target organ damage?
Systolic > 180 mm Hg
Top 5 diseases associated with hypertension in dogs
1) Renal disease - esp protein-losing nephropathies
2) Hyperadrenocorticism
3) Diabetes mellitus
4) Pheochromocytoma
5) Hyperaldosteronism
- Others = acromegaly, hypertensive meds (PPA, palladia)
Top 3 diseases associated with hypertension in cats
1) Renal disease of any variety
2) Hyperthyroidism
3) Diabetes mellitus
*Age is no a risk factor for HT, but it is a risk factor for the above diseases
Is idiopathic hypertension common in dogs and cats
No - more common in people, usually suspected in cat and dogs because the underlying disease hasn’t been found
What are the target organs that can be damaged with hypertension? (4)
- Brain = HT encephalopathy
- Eye = HT choroidopathy
- Kidney = functional decline
- Heart = adaptation like hypertrophy and diastolic dysfunction
What clinical signs do we see because of target organ damage (4)?
1) Eye = hemorrhage, retinal detachment, photophobia, acute onset blindness
2) Brain = intracranial signs (with very severe HT)
3) Kidney = proteinuria
4) Heart = new mitral murmurs, new gallop rhythms
Which patients do we measure BP and perform a fundic exam in? (2)
1) Presenting clinical signs of hypertension
2) Confirmed compatible and causative disease, Ex: diabetes mellitus
At what age, in cats, do we start to worry about hypertension?
> 10 years - risk factor for diseases that cause HT
What things should we ensure when measuring BP of our patients? (5)
- Ensure the animal is as unstressed as possible
- Utilize the same measurement method for every patient
- Patient should be conscious, unsedated, sitting/recumbent
- Measure after a period of acclimation
- Measure before any stressful procedures
How do we treat hypertension in general?
1) Treat any underlying diseases
2) Medications that modify the RAAS and vasodilate
a) RAAS = ACE-i
b) Vasodilator = amlodipine
3) Discontinue any BP elevating meds
4) Monitor fluid administration
What do we use to prevent proteinuria with renal disease?
ACE-inhibitors
What do we use to treat the cardiac abnormalities with hyperthryoidism?
Beta blockers
What drug do we use to modify the RAAS system to control hypertension?
> ACE inhibitor
- Blocks formation of AG II = blocks vasoconstriction and formation of aldosterone
- Returns vasoconstriction to normal tone = less proteinuria
What type of patient do we never want to use ACE inhibitors in?
Dehydrated patients
What is the hypertensive drug of choice in cats?
> Amlodipine = Ca++ channel blocker
- Vasodilator
+/- Add ACE-I if proteinuric
What is the hypertensive drug of choice in dogs?
> ACE-inhibitor
- Add on amlodipine if needed after one week
Clinical signs of pericardial effusion
\+ Hypotension \+ Weakness \+ Cough \+ Vomiting \+ Dyspnea \+ Collapse \+ Death
+ Chronic = lethargy, weakness, exercise intolerance, weight loss
PE findings of pericardial effusion
\+ Muffled heart sounds \+ Muffled lung sounds \+ Ascites \+ Jugular vein distension \+ Weak pulses
Diagnostics for pericardial effusion
- History and PE
- ECG
- Echocardiograph to visualize the effusion
- Thoracic radiographs
Abnormalities seen on ECG with pericardial effusion (4)
- Tachycardia
- Ventricular arrhythmias
- Attenuated QRS complexes
- Electrical alternans
Abnormalities seen on chest rads, with pericardial effusion (4)
- Large globoid cardiac silhouette
- Enlarged vena cava
- Pleural effusion
- Loss of abdominal detail
Abnormalities seen on echo with pericardial effusion (2)
+/- Masses, esp in the right atrium or heart base
- Right atrial tamponade
What is troponin I and what does it tell you?
Cardio-specific biomarker that is released from the myocardium - elevated in dogs with pericardial effusion
What do you always want to submit along with performing thoracocentesis?
CYTOLOGY - often non-diagnostic, but may lead exfoliated cells
What is the most common cause of pericardial effusion in cats?
FIP (exudative)
- Other = CHF (transudate)
What are the most common causes of pericardial effusion in dogs?
1) Idiopathic (hemorrhagic)
2) Neoplasia - HSA, heart base tumors, mesotheliomas
How do we treat first time pericardial effusion?
Pericardiocentesis
What do we recommend with repeat pericardial effusion?
Pericardectomy - subtotal or window
Life cycle (L1 to L5) of heartworm
- L1-infected dog is bit by a mosquito
- Microfilaria infect the mosquito and spread in the bloodstream, mature to L3
- L3-infected mosquito bites a dog
- Matures through juvenile L4 to adult L5 in the dog (migrates from blood > pulmonary artery right heart)
- Adult HW’s produce infective L1 microfilaria
- Mosquito bites infected dog…
Lesions seen with heartworm (4)
> Vascular = endothelial cell hypertrophy, pulmonary artery endarteritis from worm byproducts, produce thromboemboli
Pulmonary = (eosinophilic) pulmonitis, granulomas
Heart = right ventricular hypertrophy (pulmonary hypertension), caval syndrome
Renal = immune mediated glomerulonephritis, glomerulosclerosis from microfilaria
Aberrant migration systemically
What is caval syndrome?
> High worm burden that the worms overwhelm the right atrium and cause tricuspid regurgitation
- Hemolysis due to blood flowing through the worms, acting as a sieve
- Blood backs up systemicaly due to high right atrial/ventricular pressures
+/- Renal and hepatic failure due to hemolysis
What pathogen accompanies the heartworm and what problems can it cause?
> Wolbachia
- Surface antigen induces IgG response, thought to contribute to pulmonary and renal inflammation
- Released when you kill the HW
True or false - infected and asymptomatic dogs will not have microfilaria in their blood
False - need to examine blood smears at low power
Clinical signs of HW disease in dogs
+ Cough
+ Exercise intolerance = pulmonary HT and lung lesions
+ Weight loss
+ R-CHF = ascites, etc.
+ Severe = dyspnea, syncope (pulmonary HT), hemoptysis, ascites (caval syndrome)
Findings on blood smear, CBC, and chem panel with HW positive animals
- Microfilaria in the blood
- Hyperproteinemia = hyperglobulinemia
- Eosinophilia and basophilia
- Anemia from chronic disease
- U/A = proteinuria from glomerulonephritis, casts, RBC’s
+/- Abnormal renal and liver values
Findings on chest rads with HW disease
- Right caudal lung lobe interstitial to alveolar infiltrates
- Lung granulomas
- Tortuous or blunted pulmonary vessels
+/- SEVERE = enlarged pulmonary arteries
+/- Right sided heart failure
ECG findings with HW disease
Right axis deviation from right ventricular enlargement
Why is ID of microfilaria a poor choice for HW diagnosis? (5)
- Seasonality and daily periodicity complications
- Dogs may or may not be shedding microfilaria if on tx
- Dogs with pneumonitis may not have microfilaria (may be concentrated in lung parenchyma)
- Need to differentiate D. immitis from Dipetalonema reconditum
- Unisex infection may create an amicrofilaremia
What is the number one diagnostic tool for HW in dogs?
> Antigen testing
- Good sensitivity after 6 months of infection (don’t test puppies < 6 mo)
- Should still confirm positives with blood smears, thoracic rads, CBC (eosino/basophils), or Ab test
Why might an antigen test be negative (falsely)?
- Worms aren’t mature enough to shed microfilaria (too early)
- Too low of worm burden
- Unisex infection of only male worms
Treatment of canine HW (4)
- Melaromine, 3 doses = adulticide, kills L4-L5, deep lumbar injection
*Strict cage rest for 6-8 weeks - Monthly avermectin microfilariacide to kill L1
- Doxycycline = against Wolbachia to reduce arterial lesions
+/- Surgical worm removal with caval syndrome + heparin therapy
+/- Steroids - Sildenafil for hypertension
How do we prevent HW?
Monthly preventative, starting at 8 weeks of age (kill L1, L3, and L4)
*Test prior to using preventative
How does cat HW infection differ from dogs?
- Cats = infected with only 1-4 worms
- Worse arteritis
- Longer pre-patent period
- Cat HW’s live longer
What do we suspect with coughing cats?
Respiratory disease - ddx = HW or asthma
Clinical signs of feline HW
\+ Coughing \+ Gagging \+ Dyspnea \+ Tachypnea *Looks like asthma *Can die suddenly due to HW embolization
Is caval syndrome common in cats?
No - don’t have high worm burdens
PE findings of feline HW
- Abnormal lung sounds
- Cough
- Open mouth breathing
+/- Murmur
+/- Jugular distension with right CHF
Findings on CBC, blood smear, and chem with feline HW
- Microfilaremia
- Hyperproteinemia, high globulins
- Eosinophilia
- Basophilia
- Anemia from chronic disease
- U/A = proteinuria, casts, RBC’s
+/- Renal and hepatic values
What might you see on tracheal washes in feline and canine HW?
Eosinophils
Radiological findings of feline HW
- Peribronchial cuffing
- Diffuse or focal interstitial infiltrates
- Focal alveolar infiltrates
- Pleural effusion
- Enlarged caudal pulmonary arteries and pruning of pulmonary arteries
Do we use ID of microfilaria to diagnose feline HW?
No - few cats are persistently microfilaria
Do we use antigen testing to diagnose HW in cats?
No - high rate of false negatives
Reason for false negatives in antigen testing with feline HW (4)
1) Worms are not mature enough to shed microfilaria
2) Low worm burdens = difficult to detect Ag
3) Only male worms present
4) May take up to 170 days for cats to test Ag-positive post-infection
What is the first line diagnostic for feline HW?
> Antibody testing
- Negative Ab test rules it out but - Positive Ab test only confers exposure
- Highly sensitive for detecing HW Ab’s 3 months post-infection
- Use Ag testing in conjunction
Treatment of feline HW
*Assess each cat as an individual
+/- Tx with subclinical animals
> Prednisone (clinical signs are due to inflammatory reactions)
+/- Doxycycline for Wolbachia
Do we use melarsomine in cats?
NO - really only a last ditch effort
How do we prevent feline HW?
Monthly prophylactics for cats in endemic areas
