Treatment of lungworm infections in
cats
A
abstrusus
Treatment of
A abstrusus infection with off-label parasiticides has been described in
research papers and textbooks. For example, the use of ivermectin for
treating aelurostrongylosis is reported in single animals and limited
case series, but this macrolactone has inconsistent activity. Two doses are
described for off-label ivermectin, but care is required in kittens. Two
doses of off-label abamectin, 300 µg/kg subcutaneously (SC), 2 weeks apart,
have also been used for treating A abstrusus.
Several
studies have evaluated the efficacy and safety of feline parasiticides against A
abstrusus.
An oral
paste containing 18.75% fenbendazole (Panacur; MSD Animal Health) is
licensed in some countries (eg, UK) for the treatment of A abstrusus at
a dosage of 50 mg/kg PO for 3 consecutive days, and this treatment regimen has
an efficacy of 99.29%.
Two spot-on
parasiticides, one containing imidacloprid 10% and moxidectin 1% (Advocate;
Bayer Animal Health), and the other containing emodepside 2.1% and praziquantel
8.6% (Profender; Bayer Animal Health), were compared with the
formulation containing oral fenbendazole in treating feline aelurostrongylosis.
The emodepside 2.1%/praziquantel 8.6%
spot-on (Profender) and the
fenbendazole paste showed similar therapeutic performances (99.38% vs 99.29%),
while the imidacloprid 10%/moxidectin 1% spot-on (Advocate) was 100%
effective in stopping larval shedding and in curing clinical signs. This formulation (Advocate) is licensed
in some markets (eg, Australia) for the treatment of cat aelurostrongylosis.
Additionally, the adulticidal efficacy of emo depside has been demonstrated in
two randomised, placebo-controlled experimental trials to be up to 99.2%. These
studies showed that two spot-on administrations of emodepside 2 weeks apart are
safe and efficacious against cat aelurostrongylosis.
Another
macrocyclic lactone, selamectin (Stronghold; Zoetis), used topically at
18 mg/kg, reduced clinical signs after a single spot-on administration, while a
second dose after 1 month ensured improvement in respiratory function and
radiographic bronchial lesions. Selamectin at a topical dose of 6 mg/kg was
effective in eliminating larvae from the faeces of a cat after 30 days; the
same drug was effective in producing a clinical recovery and stopping larval
shedding in 9/10 cats infected with A abstrusus.
Milbemycin
oxime 4 mg/kg (plus praziquantel 10 mg/kg) (Milbemax; Novartis Animal
Health) PO at 2 week intervals was also effective in stopping L1 elimination
and resulted in resolution of clinical signs over a period of 6 weeks in a cat
with clinical aelurostrongylosis.
A novel
topical formulation containing fipronil 8.3% w/v, (S)-methoprene 10% w/v,
eprinomectin 0.4% w/v and praziquantel 8.3% w/v (Broadline; Merial) was
evaluated for efficacy against larval and adult A abstrusus in
experimentally infected cats. This formulation is licensed in some countries
for the treatment of A abstrusus. Using treatment time points based on
the life cycle of A abstrusus in the cat (ie, from inoculated L3s to
adult stages), the study demonstrated that eprinomectin has high efficacy
against all A abstrusus stages; for example, 99.6% efficacy against
adult stages in the feline definitive host. In cats naturally infected with A
abstrusus, this formulation showed 90.5% efficacy based on larval counts.
T
brevior
Information
on control options for troglostrongylosis in domestic cats is
incomplete. The adminis - tration of imidacloprid 10%/moxidectin 1% (Advocate)
in a cat appeared unsuccessful, but this may have been due to the severe
clinical signs and extensive lung lesions already present at the point of
referral. A kitten infected with T brevior returned negative scores upon
both copromicroscopic and biomolecular examinations for 3 months after a single
administration of Advocate and showed a corresponding improvement in
severe cardiorespiratory signs.
A single
administration of milbemycin oxime 2 mg/kg (Milbemax) was efficacious in
stopping larval shedding in one cat with a subclinical mixed infection of A
abstrusus and T brevior, but the same drug was effective only
against A abstrusus in another cat from the same litter, which died due
to infection with T brevior despite the treatment.
The topical
formulation containing emodepside 2.1%/praziquantel 8.6% (Profender)
recently showed promise in the treatment of two kittens with mixed lungworm
infections (T brevior and either A abstrusus or C aerophila).
Respiratory signs resolved after one or two administrations of the spot-on
solution, and larval (T brevior and A abstrusus) and egg (C
aerophila) shedding was also eliminated 2–4 weeks after treatment.
The spot-on
containing eprinomectin (Broadline) proved 100% efficacious in stopping
larval shedding in a few cats with natural T brevior infection. It
recently showed 100% efficacy against developing larvae and adults of T
brevior under experimental conditions.
C
aerophila
Available
data on the treatment of C aerophila infection in cats include reports
on the efficacy of repeated administrations of a variety of dosages of
injectable or oral levamisole and off-label abamectin.
Importantly,
the spot-on formulation containing moxidectin 1% (Advocate), which was
efficacious against aelurostrongylosis, demonstrated ~99.8% efficacy in
stopping egg shedding and eliminating clinical signs in cats with lung capillariosis.
The safety
and efficacy of the topical combination containing eprinomectin (Broadline)
was evaluated against helminths, including Capillaria species, in
domestic cats. An efficacy of 99.6% in reducing counts of Capillaria
eggs was reported after treatment. Although no morphological identification of
the eggs was performed, it was assumed that the vast majority were C
aerophila. A very recent study has demonstrated that a single treatment
with Broadline in naturally infected cats is able to reduce the C
aerophila parasite burden and to lower or eliminate faecal egg shedding.
Continued from page 14 Any respiratory sign in an at-risk cat (eg, free-roaming
or kitten) should ring an alarm bell for clinicians working in lungwormendemic
areas or with travelling pets.
In
general, easy-to-apply topical parasiticides are a suitable choice for treating
cat lungworms, because of safety and ease of administration, especially when
multiple dosing is required.
