Exam 2 - Lecture 19 Flashcards
Lecture 19
Dirofilaria immitis Infection in Cats
-Cats may also be infected with heartworms
* Being a “suitable host” is not the same as being a “preferred” or “competent” host
-Parasite load is small with only 1 or 2 worms
-Microfilaria are usually not
produced
-Do not significantly contribute to maintenance of the parasite in host populations
Dirofilaria immitis Infection in Cats Information
-Usually only 1 worm is
present‐heart is so small
-Cats commonly have
heartworms in ectopic sites
and fall victim to sudden
death
-Worms may migrate to the
brain
HARD aka “Heartworm Associated Respiratory Disease”
-Clinical disease associated with inflammation in pulmonary vasculature
-Occlusion of airways!
-Asthma‐like disease
-Clinical signs include: dyspnea, coughing, vomiting, tachypnea (rapid open mouth breathing), anorexia, lethargy
-Eosinophilia, basophilia
-Serology pos/neg based on host response to infection
Feline Heartworm Disease
-Wolbachia well established as facilitating factor for inciting bronchial reactivity w/ HARD
-3 phases of HARD:
-Phase 1 w/ clinical signs
-Phase 2 w/out clinical signs due to immunomodulatory activity by parasite
-Phase 3 w/ clinical signs as parasite control of host response diminishes
-Diagnostic implications!
Serologic Testing in Cats
-Antibody testing:
-High sensitivity
-Early exposure (Phase 1)
-Late‐stage disease (Phase 3)
-Antigen testing:
-High specificity
-Sensitivity compromised by low worm burden, low circulating antigen
-Requires adult worms (~2+)
-Good for Phase 2 and Phase 3 disease process
-Symptomatic infected cats may test negative 25%‐50% of time
Management of Feline Heartworm Disease
-No approved adulticidal regimen
-Manage symptomatically:
-Corticosteroids +/‐ based on recent studies
-Important to stay abreast of clinical literature
-Monthly HW prophylaxis:
-IVM & MOX have shown minor long‐term adulticidal properties
-Not FDA Approved treatment
-Prevention of further infection w/CHW
-Doxycycline to manage Wolbachia
-Open communication with client about risk and prognosis
Why Felines Should Receive Heartworm Prophylaxis
-Cats are susceptible to infection the same as dogs
-Heartworm disease in cats is more severe than dogs and often fatal
-No safe and effective adulticide therapy is available
-Heartworm disease/infection is 100% preventable:
-Heartgard for cats (Ivermectin)
-Advantage Multi for cats (Moxidectin)
-Both drugs work retroactively to kill HW L3 acquired in 30 days prior to treatment-
Heartworm in Ferrets
-Caused by Dirofilaria immitis:
-Obligate mosquito transmission just like dogs and cats
-Previous experience suggested that expression of disease was similar to cats
-Now recognized to be a blend of characteristics seen in dogs and cats:
-Ferrets are highly susceptible
-Recovery of adult worms similar to dogs
-Low & transient microfilaremia
-Similar to cats
Clinical Significance
-Respiratory:
* Coughing
* Dyspnea
* Exercise Intolerance
* Pleural effusion
-Cardiovascular:
* Heart murmur
* Cyanosis
* Caval syndrome
-Billiary/Urinary:
* Liver/abdominal enlargement
* Billirubinuria
* Hemoglobinuria
-General ADR:
* Vomiting (similar in cats)
* Lethargy
* Anorexia
* Weight loss/emaciation
* Posterior paresis
Expression of Heartworm Disease and Chemotherapy in Ferrets - Compared to Dogs
-Highly susceptible, worms likely to mature to adult stage (~14 worms, male & females)
-Antigen test accurate but susceptible to worm #’s, low antigenemia, etc.
-Adulticidal therapy tolerated & effective:
-Low dose 2.5mg/kg IM, q 24 hrs
(x2), 70% efficacy w/ cardiac/respiratory effects
-Higher dose, 3.25mg/kg IM, q 24 hrs @ or AHS split dose: 81 to 83% effective
-Prevention w/ macrocyclic lactone drugs @ monthly administration is effective for prevention
Expression of Heartworm Disease and Chemotherapy in Ferrets - Compared to Cats
-Microfilaremia often transient (short duration), or absent
-Disease expression primarily inflammatory w/ respiratory involvement
-Adulticidal therapy not FDA approved
-Ivermectin & Moxidectin administered monthly recognized safe and effective for prevention of disease
