Page 112 - Problem-Based Feline Medicine

104 PART 2 CAT WITH LOWER RESPIRATORY TRACT OR CARDIAC SIGNS

Treatment Pathogenesis

Bacterial pneumonia – antimicrobial therapy, par- Dirofilaira immitis larvae (L3) infect the cat follow-
enteral if debilitated or septic, and oral if cat is an out- ing a bite from an infected mosquito.
patient. Antibiotic selection best based upon specific
Larvae molt and migrate to the pulmonary arteries,
culture and sensitivity testing.
arriving as immature heartworms (L5) approxi-
Fungal pneumonia – systemic itraconazole at 5–10 mately 100 days or more after initial infection.
mg/kg PO daily is the drug of choice. If there are CNS
Cats typically have fewer adult worms than dogs.
signs with cryptococcosis, fluconazole (2.5–5.0 mg/kg
Less than six adults is usual and often only one or two
PO daily) crosses the blood–brain barrier.
worms are present. Adult worms live shorter lifespans
Viral pneumonia – mostly supportive. in cats compared to dogs, typically 18 months to 3
years.
Supportive care is essential. Adequate airway and sys-
temic hydration are essential for mucociliary clearance. The prevalence of heartworm infection in cats is approx-
Intravenous crystalloids are important for systemic imately 5–10% of the infection rate in dogs in the same
hydration, but should be used judiciously to avoide location, although the ratio may be higher in some areas.
over-hydration. Nebulization with saline may be help- A recent report from Florida showed 5% of necropsied
ful. Physical therapy, oxygen enrichment and bron- cats were positive for the parasite, and 17% of tested cats
chodilator therapy may be helpful. were seropositive. In a similar study in Georgia, D. immi-
tis were found in four of 184 cats (2.1%).
Prognosis Indoor cats are as likely to be infected as outdoor cats.

Prognosis depends on the etiological agent and the In some studies, male cats had a higher incidence of
severity of the infection. infection and had a higher worm burden.
Bacterial pneumonia has a fair to good prognosis, but Cats infected with heartworm may be asymptomatic,
the prognosis is worse in patients with pre-existing ill- have chronic coughing, acute respiratory distress or
nesses or patients on immunosuppressive therapy. die suddenly.

The prognosis for aspiration pneumonia depends on Clinical signs are most likely to occur at the time of
the degree of tissue damage. arrival of the immature heartworms in the lungs or with
death of adult worms.
Cryptococcal pneumonia generally has a fair to good
prognosis, although it is poor if CNS signs are present. Initial arrival of the immature worms results in a
marked inflammatory response, and signs similar to the
feline asthma/bronchitis complex may occur. With mat-
uration to the adult worm, signs may improve or
Prevention resolve.
Avoid the source of infectious agents (i.e., aspergillus Death of adult heartworms may produce acute severe
from bird droppings) and risk factors (i.e., aspiration). pulmonary inflammation with edema, and an acute res-
piratory distress syndrome characterized by general-
ized respiratory failure.
FELINE HEARTWORM DISEASE
Clinical signs
Classical signs
Harsh and productive coughing is the most common
● Cough.
sign.
● Acute-onset dyspnea.
● Vomiting together with respiratory signs. Dyspnea may be acute and life threatening. Acute
dyspnea is associated with pulmonary thromboem-