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© 2017 ASPCA®. All Rights Reserved.
Enjoy the music! • The webinar will begin at its scheduled time.
• Join the webinar using built-in computer audio or dial 669-900-6833 or 646-558-8656
Webinar ID: 145-807-572
Takin’ It To The Heart: New Insights on Managing
Heartworm Disease in Shelter Animals
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© 2017 ASPCA®. All Rights Reserved.
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© 2017 ASPCA®. All Rights Reserved.
© 2019 ASPCA®. All Rights Reserved.© 2019 ASPCA®. All Rights Reserved.
Brian A. DiGangi, DVM, MSDiplomate, ABVP (Canine & Feline Practice, Shelter Medicine Practice)
Senior Director, Shelter MedicineShelter Outreach, ASPCA
Takin’ it to the heart:New insights on managing heartworm disease in shelter animals
© 2019 ASPCA®. All Rights Reserved.© 2019 ASPCA®. All Rights Reserved.
When should spay-neuter surgery be performed?How should we prepare dogs for relocation?
What does “activity restriction” mean and is it really that important?
What are the long-term effects of HW infection?When will a treated dog be cleared?
Frequently Asked Questions…
© 2019 ASPCA®. All Rights Reserved.
• All dogs, cats and ferrets are at risk• Administer preventives year-round
Part 1
Review
Test for antigen and microfilaria• On intake• Annually
Treat with 3 doses of melarsomine• Safest• Most effective• Most cost-effective
© 2019 ASPCA®. All Rights Reserved.
I currently have several heartworm positive dogs in my rescue. They are
all in various stages of treatment.
Some of the vets involve want to spay before injections. Others refuse
surgery until after treatment.
What is your recommendation?
© 2019 ASPCA®. All Rights Reserved.
Peterson et al., 2014• 15 HW + mixed breed dogs• No or mild clinical signs• Cardiovascular-sparing anesthesia• No clinically relevant complications • 24 hours • 7-10 days post-op
Heartworm Treatment & Spay-Neuter
© 2019 ASPCA®. All Rights Reserved.
Heartworm Treatment & Spay-Neuter
12.6%
44.9%
20.2%
5.6%7.6% 8.1%
Prior to diagnosis After diagnosis, prior totreatment
After beginningdoxycycline
After completingdoxycycline
After melarsomine Other
When is spay-neuter performed in relation to adulticidal therapy?
© 2019 ASPCA®. All Rights Reserved.
Heartworm Treatment & Spay-Neuter
12.6%
44.9%
20.2%
5.6%7.6% 8.1%
Prior to diagnosis After diagnosis, prior totreatment
After beginningdoxycycline
After completingdoxycycline
After melarsomine Other
When is spay-neuter performed in relation to adulticidal therapy?
© 2019 ASPCA®. All Rights Reserved.© 2019 ASPCA®. All Rights Reserved.
But what happens when…
I am fostering a Yorkie that came in with heartworms 4 months ago
which have now been treated. She needs to be spayed, she has 3 mammary gland tumors that need
to be removed and needs a dental.
When can we start to get this all taken care of?
© 2019 ASPCA®. All Rights Reserved.© 2019 ASPCA®. All Rights Reserved.
Peterson et al., 2014…heartworm-positive dogs with an ASA patient classification score greater than 2 were treated for their heartworm disease, including a minimum 4-week convalescent period prior to re-evaluation and surgical sterilization.
AHS, 2018Surgery can then be performed 6 months after adulticidal treatment if the dog has recovered sufficiently.
© 2019 ASPCA®. All Rights Reserved.© 2019 ASPCA®. All Rights Reserved.
Hirano, 1992• 4 weeks after dead HW insertion…• Pulmonary arterial pressure (PAP) recovered• Blood flow between thromboemboli recovered• Effects depended on severity of lesions before insertion
•In HW + dogs….•Clinical signs and laboratory findings worsened until week 4
© 2019 ASPCA®. All Rights Reserved.
What 2 components of the life cycle are needed for transmission?
WisconsinDept. of Agriculture Trade and Consumer Protection
Heartworm positive dogs are generally not eligible for import.
© 2019 ASPCA®. All Rights Reserved.
© 2019 ASPCA®. All Rights Reserved.
© 2019 ASPCA®. All Rights Reserved.
Minimizing Transmission During Relocation
Microfilaria Status Treatment Rationale
NegativeAdminister heartworm preventive Prevent mf development
Begin doxycycline Inhibit mf developmentRepeat mf test in 7 days Confirm lack of circulating mf
© 2019 ASPCA®. All Rights Reserved.
Minimizing Transmission During Relocation
Microfilaria Status Treatment Rationale
Positive or Unknown
Apply topical moxidectin ORAdminister heartworm preventive
+Apply topical insecticide
Eliminate most mfPrevent infection of mosquitoes & larval transmission
Begin doxycycline Inhibit mf development, render L3 non-infective
© 2019 ASPCA®. All Rights Reserved.
Do we need to exercise restrict non-treated heartworm positive dogs? The issue then is
that staff is still exercise restricting these untreated dogs by keeping them out of play
group.
What about exercise right after heartworm treatment is completed? I have a dog that
wants to run.
© 2019 ASPCA®. All Rights Reserved.
• Delays onset and extent of clinical disease
Rest and Recovery
Right heart failure
Increased cardiac
workloadCapillary damage
Increased blood flow
Aerobic
activ
ity
© 2019 ASPCA®. All Rights Reserved.
• Provide safe physical and mental stimulation• Meet needs for socialization• Reduce stress and anxiety
Rest and Recovery
© 2019 ASPCA®. All Rights Reserved.
• Begin upon diagnosis• Clinical signs ≈ restriction
• Greatest risk 7-10 days after injection• Crate, small room, leash walks
• Continue for 6-8 weeks
Rest and Recovery
© 2019 ASPCA®. All Rights Reserved.
My sister, a vet tech, heard that I was planning to adopt a dog who had heartworm, and she told me it was a huge
mistake.
She told me that even if caught and treated early, the dead heartworms still wreak havoc on the dog’s heart and lungs. She told me “It’s not a matter of ‘if’ the dog
experiences complications, it’s ‘when.’”
She went on to say that dogs living a full life after having heartworm is the exception, not the rule, and that she
could almost guarantee me that any dog with heartworm, even after being treated, will have a short life and a sudden death. She told me that a year from
now, I could be taking her out to go to the bathroom and she could just drop dead. She told me it was very likely.
© 2019 ASPCA®. All Rights Reserved.
Long-term Effects
Right heart failure
Increased cardiac
workloadCapillary damage
Increased blood flow
Blood clots (PTE)
Worm death +
Inflamma-tion
© 2019 ASPCA®. All Rights Reserved.
Even if caught and treated early?
S. Jones
S. JonesNormal pulmonary artery <6 mos. after experimental infection
© 2019 ASPCA®. All Rights Reserved.
Number of worms+
Duration of infection≈
Significant pathology+
Clinical diseaseS. Jones
Mummified adult worm remnants
S. Jones
Scarring
Irreversible chronic obstructive disease
© 2019 ASPCA®. All Rights Reserved.
Duck, ~1.5 year old MN Pittie, presented to me after newly being adopted. He was
transported from South Carolina to a rescue in Pennsylvania. In South Carolina, Duck tested positive for HW disease, was started on doxycycline and treated with
melarsomine on 10/8/18 and 10/9/18. He has been on monthly HW prevention since
then. We retested Duck 3/16/19 and he remains positive.
Should I retreat this dog?
© 2019 ASPCA®. All Rights Reserved.
• Antigen tests can’t distinguish between dead and living worms
• Melarsomine only affects adult stages• Preventives + doxycycline mask detection
• Worms may continue to die for >1 month
Should I re-treat?
© 2019 ASPCA®. All Rights Reserved.
Give 2 doses melarsomine
• Antigen test 9 months after last injection
Should I re-treat?
Positive
Re-test in 6 months
Negative
© 2019 ASPCA®. All Rights Reserved.
Should I re-treat?
X X=
X=
X=https://cheezburger.com/7826984448
© 2019 ASPCA®. All Rights Reserved.
Should I re-treat?
=
https://cheezburger.com/7826984448
X
X= XX= XX
© 2019 ASPCA®. All Rights Reserved.
Hoerauf 2003• >95% loss of Wolbachia and
microfilaremia after 12 months(Humans, 200 mg/day x 6 wks)
Rossi 2010• Wolbachia and microfilaria numbers
remain low for 12 months (Dogs, 10 mg/kg/day x 21 days, every 6 mos)
Should I repeat doxycycline?
McCall 2014
© 2019 ASPCA®. All Rights Reserved.
Hoerauf 2003• >95% loss of Wolbachia and
microfilaremia after 12 months(Humans, 200 mg/day x 6 wks)
Rossi 2010• Wolbachia and microfilaria numbers
remain low for 12 months (Dogs, 10 mg/kg/day x 21 days, every 6 mos)
Should I repeat doxycycline?
McCall 2014
To prevent rebound of Wolbachia populations, the course of doxycycline should be repeated every 12 months.
© 2019 ASPCA®. All Rights Reserved.
When are they “negative”?
9 mos. 6 mos. 6 mos.
© 2019 ASPCA®. All Rights Reserved.
When are they “negative”?
9 mos. 6 mos. 6 mos.
© 2019 ASPCA®. All Rights Reserved.
Key Resource
https://www.sheltervet.org/assets/docs/ASV.Heartworm%20Management.pdf