special project combined
TRANSCRIPT
AN ASSESSMENT OF THE CLINICAL EFFICACY OF PYRANTEL PAMOATE AS THE ANTEHELMINTH TREATMENT OF CHOICE
IN AN OPEN ADMISSION SHELTER IN PASCO COUNTY, FLORIDA.
By JALEH KHORSANDIAN-FALLAH, DVM
SPECIAL PROJECT
DEPARTMENT OF GLOBAL HEALTH COLLEGE OF PUBLIC HEALTH
UNIVERSITY OF SOUTH FLORIDA TAMPA, FLORIDA
JULY 2015
APPROVED:
___________________________________ _____ Project Supervisor Name & Degrees Date
___________________________________ ______ Second Reader Name & Degrees Date
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TABLE OF CONTENTS
List of Tables ........................................................................................................... iii List of Figures .......................................................................................................... iv Abstract .................................................................................................................... v. Chapter One: Introduction ........................................................................................ 1 Background ..................................................................................................... 1 Setting ............................................................................................................. 6 Purpose ........................................................................................................... 7 Chapter Two: Methods ............................................................................................. 8 Collection ........................................................................................................ 8 Processing ....................................................................................................... 8 Chapter Three: Results ............................................................................................ 10 Chapter Four: Discussion ........................................................................................ 12 Chapter Five: Recommendations ............................................................................ 15 Deworming Protocols ................................................................................... 15 Intake Recommendations ............................................................................. 16 Monthly Recommendations .......................................................................... 17 Adoption Recommendations ........................................................................ 18 Screening Recommendations ....................................................................... 19 Environmental Control Recommendations .................................................. 19 Client and Staff Education Recommendations ............................................. 20 Recommendations for Further Study ............................................................ 21 Strengths of Study ........................................................................................ 21 Limitations of Study ..................................................................................... 21
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Chapter Six: Conclusions ........................................................................................ 23 References ............................................................................................................... 24
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LIST OF TABLES
Table 1: Drug Cost Comparison Chart ........................................................ 15 Table 2: Drug Comparison Chart ..................................................................... 16
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LIST OF FIGURES
Figure 1: Pasco County Vector Map .................................................................. 10
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Abstract
With the emergence of highly effective monthly anti-parasitic treatments in the United
States, the prevalence of intestinal parasites has fallen dramatically in the owned pet population
(Gates & Nolan, 2014)(Irwin, 2002). However, the stray animal population remains an untreated
group with high rates of exposure to parasitic organisms. Intestinal parasitism is common in
animal shelters; with roundworm, whipworm, and hookworms prevalent (Blaburn BL, Lindsay
DS, Vaughn JL, 1996) (Little et al., 2009)(Anna Ortuñoa, 2014). These parasites are classified as
zoonotic agents, although human infections are uncommon in the United States and are generally
associated with the young, elderly, and immunocompromised (I D Robertson, Irwin, Lymbery, &
Thompson, 2000). Treatment of intestinal parasites is necessary to ensure individual and herd
health, prevent environmental contamination, and limit exposure of the general public (Traversa
et al., 2014). Due to limitations in shelter resources, individual fecal screening at time of shelter
admission is not feasible (Giulia Simonato, Antonio Frangipane di Regalbono, Rudi Cassini,
Donato Traversa, Paola Beraldo, Cinzia Tessarin, 2015)(Little et al., 2009). The high presence of
parasitic infections in shelter animals(Blaburn BL, Lindsay DS, Vaughn JL, 1996) (Anna
Ortuñoa, 2014) is such that prophylactic anthelminthic treatment is considered a standard of care
for most public shelters. Effective treatment protocols for intestinal helminthes in the shelter
setting should be based on parasitic prevalence, ease of administration, and cost effectiveness.
The purpose of this study is to assess the efficacy of single dose pyrantel pamoate at 10mg/kg as
the sole anthelmintic agent in shelter dogs after admission to Pasco County Animal Services
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(PCAS). 58 of 67 sampled animals screened positive for intestinal parasites, indicating an 86.5%
intestinal parasite disease prevalence of the intake dog population. Pyrantel pamoate was found
clear 100% of all roundworm infections, 12.1% of all hookworm infections, and 0% clearance of
whipworms. Based on prevalence data and clinical efficacy findings, pyrantel pamoate at
10mg/kg as the sole anthelminthic agent at PCAS is ineffective intervention. Alternate
deworming protocols should be pursued based on spectrum effects, ease of compliance, and cost
considerations.
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CHAPTER 1
INTRODUCTION
Background
The presence of intestinal parasites in our companion animals is of human public health
importance, due to the intimate association of humans and animals (Zasloff & Kidd,
1994)(Waltner-Toews, 1993). Companion animals live in extremely close association with
people, often eating, defecating, sleeping and performing grooming behaviors within the
confines of the home and surrounding green areas (Robertson, Irwin, Lymbery, & Thompson,
2000)(Paoletti et al., 2015). The control of parasites in companion animals is necessary to limit
the exposure of humans to zoonotic disease. Zoonotic infections transmitted from the domestic
canine are varied and include but are not limited to the following: cutaneous larva migrans,
giardiasis, baylisascariasis, microsporidiosis, dipylidiasis, echinococcosis, visceral larva migrans,
ocular larva migrans, neural larva migrans, and trichuriasis (Gavin, Kazacos, & Shulman,
2005)(Georgi & Sprinkle, 1974)(Gavignet, Piarroux, Aubin, Millon, & Humbert,
2008)(Gavignet et al., 2008) (Patricia, Leonor, & Nelson, 2008). Although such infections are
rare, the immunocompromised, elderly, and young are most susceptible to infection. From a
public health perspective, failure to treat carrier animals results in an unnecessary exposure of
the general public (Traversa et al., 2014)(Sandhu & Singh).
Control of parasites in the domestic dog has additional public health consequences in the
instance of publicly funded public health agencies, such as animal services. The control and care
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of stray animals in our community is often an unappreciated public health service in the United
States. One has only to look to less developed nations to see that failure to treat and control the
stray animal population results in increased exposure of humans to zoonotic diseases such as
rabies, larval migrans, infections transmitted by fleas and ticks, and additional intestinal diarrheal
diseases (Mateus, Castro, Ribeiro, & Vieira-Pinto, 2014)(Traub et al., 2014).
Cutaneous larva migrans (also known as creeping eruption) is a human infection of
zoonotic hookworm species. Ancylostoma braziliense and A. caninum are the most common
agents associated with this disease, and are natural pathogens of canines and felines(Bowman,
Montgomery, Zajac, Eberhard, & Kazacos, 2010). The life cycle of Ancyclostoma begins when
eggs are passed in the stool of an infected cat or dog. Within 24 to 48 hours of excretion, the
larvae hatch. The released rhabditiform larvae thrive in moist soil or feces, and after 5 to 10 days
(and two molts) they transform into infective filariform (third-stage) larvae. These infective
larvae remain viable for 3 to 4 weeks under favorable conditions. On contact with the animal
host, the larvae penetrate the epidermis and are transported through the vascular system to the
lungs. The larvae ascend the pulmonary tree until they reach the pharynx, and are swallowed.
The larvae’s final destination is the small intestine, where maturation into sexually mature adults
occurs. Adult worms attach to the intestinal wall with piercing mouthparts and begin to feed and
reproduce. Some larvae become arrested in the tissues, and serve as source of recurrent
infections, known as larval leak. Humans may also become infected when filariform larvae
penetrate the skin. However with most species of hookworm, the larvae cannot mature further in
the human host, and migrate aimlessly within the epidermis. Some larvae may persist in deeper
tissue after finishing their skin migration. Manifestation of hookworm larval migrans may appear
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as a pruritic, erythematous creeping eruption. Most forms of infection are self-limiting. (CDC,
2015)(Traub, 2013)(Inpankaew et al., 2014)
Trichuriasis is caused by various species of Trichuris, also known as whipworms. This
family of nematodes does not undergo tissue migration, and larval and adult forms are normally
found only in the intestines. Generally, human cases are caused by Trichuris trichiura, with
zoonotic trichuriasis associated with animal parasites Trichuris vulpis and Trichuris suis.
Trichuris spp. have a direct life cycle, and mature in a single host. Infection of the host occurs
when it ingests embryonated eggs from the environment. The eggs hatch in the small intestine
before finishing their maturation in the large intestine. The adult whipworms are found in the
cecum and adjacent portions of the large intestine, and shed their eggs in the feces. T. vulpis
begins to produce eggs in approximately 70 to 90 days in dogs. Human infections of T. vulpis are
generally silent, but heavy infections may manifest as chronic diarrhea, which may be bloody.
Additional symptoms may include abdominal pain and distention, nausea, vomiting, flatulence,
headache, weight loss, malnutrition, and anemia. Nervousness, anorexia, and urticaria may also
be reported. Untreated and severe infections can lead to clubbing of fingers in children.
Complications from trichuriasis may include rectal prolapse, appendicitis, colitis, and proctitis.
Very rare cases of visceral larva migrans, due to T. vulpis, have been reported in humans (Health,
2005).
Toxocariasis is the parasitic disease caused by the larvae of two species of roundworms:
Toxocara canis and Toxocara cati. The dog is the definitive host of Toxocara canis, with human
acquired infection considered accidental(Gawor, Borecka, Marczyńska, Dobosz, & Żarnowska-
Prymek, 2014). Infected dogs shed unembryonated eggs in their feces, which transform and
become infective in the environment. Following ingestion by the canine host, the eggs hatch and
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larvae penetrate the gut wall. The age of the animal determines cycle of the parasite, with
younger dogs undergoing larval migration into the tissues, through the pulmonary tree and into
the gastrointestinal system, until the adult worms develop and oviposit in the small intestine. In
older dogs encystment of larvae into the tissues is more common. Transmammary and
transplacental infection occurs between bitch and pups when encysted stages are reactivated
during late pregnancy. Due to higher rates of shedding, puppies are the major source of
environmental egg contamination. In addition to ingestion of infective eggs, Toxocara canis can
also be transmitted through ingestion of paratenic hosts, via the ingestion of encysted larvae.
Humans are accidental hosts, infected through the ingestion of infective eggs in contaminated
soil, or infected paratenic hosts. After human ingestion, the eggs hatch, larvae penetrate the
intestinal wall and are carried by the circulation to a variety of tissues. (CDC, 2015) While the
larvae do not undergo any further development in these sites, they can cause severe local
reactions that are the basis of toxocariasis. The two main clinical presentations of toxocariasis
are visceral larva migrans and ocular larva migrans, although literature indicates that
toxocadiasis can affect many organs systems. (Carvalho & Rocha, 2011)(Fan, Liao, & Cheng,
2013)(Gavignet et al., 2008)
In the interest of public safety and animal welfare, control of the stray dog population
through rehabilitation and adoption of domesticated dogs is elected over euthanasia of stray
animals in Pasco County. The care of the homeless dog population requires special
consideration, as facilities are generally over crowded with insufficient sanitation practices and
constant influx of infected animals resulting in increased risk of disease transmission of the herd.
With animals coming in from the field daily, the practice of vaccination and deworming of every
animal at intake is vital to the continued health of the individual animals and herd. Failure to
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control infectious agents in the animal shelter results in increased morbidity, increased use of
medical resources of each animal, increased length of stay, and decreased adoptability(Litster,
Allen, Mohamed, & He, 2011). All these factors act to drain county resources, increase exposure
of the public to infectious agents, and affect the quality of life for the animals in the shelter.
The current deworming protocol consists of a single does of pyrantel pamoate on
admission, dosed orally at 10mg/kg. Pyrantel pamoate is a combination of pyrantel and pamoic
acid. This agent acts as a depolarizing neuromuscular blocking agent, causing sudden
contraction, followed by paralysis, of the helminthes. In addition, it acts as a cholinesterase
inhibitor and ganglionic stimulant. As a consequence of paralysis, helminthes are unable to
maintain their position in the intestinal lumen and are expelled from the body in the fecal stream
by peristalsis. Pyrantel pamoate is not vermicidal or ovicidal. Not systemically absorbed, this
medication is extremely safe in the young, pregnant, lactating and senior animals. In the dog,
total gut transit time ranges from 1,294 minutes to 3,443 minutes (Boillat, Gaschen, & Hosgood,
2010). This likely translates into an estimated time of oval shedding after deworming of 21.56 to
57.38 hours. Numerous studies have been performed, verifying the efficacy of pyrantel pamoate
against roundworms and hookworms (Kopp, Kotze, McCarthy, Traub, & Coleman, 2008)(Todd,
Crowley, Scholl, & Conway, 1975)(Dryden & Ridley, 1999)(Klein, Bradley, & Conway, 1978).
However, evidence of resistance to pyrantel pamoate has been reported(Kopp, Kotze, McCarthy,
& Coleman, 2007)(Kopp, Coleman, Traub, McCarthy, & Kotze, 2009). It is also of note that
pyrantel pamoate is not effective against whipworms, which is of zoonotic importance (Plumb,
2002).
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Setting
Pasco County Animal Services is an open admission shelter, meaning the facility will
accept any animal for any reason. The facility consists of 2 main buildings for the housing and
care of animals. The primary building (Building A) houses the adoption center and support staff,
large and small canine adoptions, feline adoption, feline isolation, feline freedom room,
veterinary services, and several small grass areas for potential adoptions meet and greet.
Building A was constructed with large windows, profuse natural light, and high volume air
turnover air handling systems. The general lighting, air quality, humidity levels, and sound
conduction is fair to good. The large dogs are housed in rectangular runs with coated metal
grates suspended over painted concrete with in-ground outflow drains beneath each run. Cement
block walls separate the lower 4 feet of the runs with chain link fencing extending from the 4 to
8 feet. The large dogs are able to physically interact with adjacent neighbors through the chain
link fence. Small dogs and puppies are housed in small kennels with cement barriers and
stainless steel bar doors. Time spent outside of the kennel is related to walking in a common
grass yard, free run in a common grass enclosure, and smaller communal grass enclosures during
kennel cleaning and adoption meetings.
Building C is the secondary animal housing facility constructed completely of concrete
and retrofitted with an insufficient air handling system. The large dog runs are grouped into 4
sections. Each run is separated from the neighbor with a shared stainless steel barrier extending
from the ground to 4 feet. Chain link extends up from 4 to 8 feet. The animals rest directly on a
painted concrete floor. The in-ground waste drains are positioned directly in front of the run
door. Air quality and lighting is significantly inferior to Building A, with an eye-watering
ammonia smell each morning before cleaning rounds. Time spent out of the runs included
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walking on common grass yard, free time in a common grass and dirt play yards, and separate
outdoor grass kennels which were rotated daily between all 4 animal sections.
Cleaning of all animal runs occurs in the morning by animal care technicians and work
release prisoners. Cleaning protocols, deep cleaning protocols, and disinfection protocols are
implemented based on length of animal stay, clinical disease, and movement of animals to
different locations. Fecal waste in the external yards is removed daily and disposed of. Cleaning
and disinfection agents include detergents, trifectant (Potassium peroxymonosulfate 21.41%,
Sodium Chloride 1.5%, Other Ingredients 77.09%), and alternate titrations of bleach. Animal
Care technicians are responsible for determining cleaning protocol (cleaning vs deep clean vs
disinfection) on a daily basis, with veterinarian involvement generally associated with disease
control and training events.
Purpose
The purpose of this study is to evaluate the efficacy of the PCAS’s current deworming
protocol. As the current helminthic prevalence of dogs at PCAS is unknown, a survey will be
conducted to establish baseline data. After prevalence data have been obtained and
geographically mapped within Pasco County, a risk map will be generated. The use of risk maps
and cluster analysis will highlight areas of human exposure to infectious ova produced by the
stray dogs. Establishing prevalence data is also necessary in the creation of an appropriate
deworming protocol.
The second portion of this project is to determine the efficacy of our current deworming
protocol in a clinical shelter setting. The hypothesis tested is that a dog dewormed with a single
dose of pyrantel pamoate at 10mg/kg will test negative for parasite ova in feces 5760- 7200
minutes after deworming event.
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CHAPTER 2
METHODS
Collection
Fecal samples were collected from 67 canine animals at intake into PCAS facility during
the month of May 2015, prior to deworming with pyrantel pamoate. Canine intakes include stray
animal, owner surrenders, adoption returns, and animal custody cases. Each animal was assigned
an identification number, and researchers were blinded to an animal’s intake category, location
of origin, previous medical history or fecal flotation results. Fecal samples were collected
directly from animal, or from individual animal housing. A range of 2 to 5 grams of fecal
material is required for analysis by flotation. After collection animals were dewormed as per
standard operating procedure of PCAS. Dosed at 10mg/kg orally, small volumes of pyrantel
pamoate were administered per os. Animals requiring larger volumes of pyrantel pamoate, who
exhibited fractious behavior, or who refused administration of the drug were offered canned diet
with pyrantel pamoate mixed in.
Processing
Fecal flotation was performed on each sample via a zinc sulfate flotation and
centrifugation method. Centrifugation was performed at 1300 rpm for 6 minutes for all samples.
Samples with displaced coverslips during the centrifugation process were floated an additional
10 minutes. All samples were evaluation under 40x microscopy by an experienced veterinary
technician or veterinarian. Animals were followed for 4 to 5 days and a 2nd fecal sample
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collected and flotation technique performed. Animals excluded from the study-included animals
treated with additional anthelminthic medications or were released prior to 2nd sample collection.
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CHAPTER 3
RESULTS
A total of 67 fecal samples were collected at intake. Of the 67 intake samples collected,
only 9 animals screened “no parasites seen” or NPS. The remaining 58 samples (86.5%)
screened positive for intestinal parasites. In regards to the positive samples; 45 (77.5%) screened
hookworm positive, 13 whipworm positive (22.4%) , 7 roundworm positive (12%), including a
single case of Baylisascaris (1.7%) grouped under roundworms. See figure 1.1
Figure 1 Pasco County Canine Zoonotic Vector Map
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A total of 50 samples sets were analyzed to evaluate the efficacy to pyrantel pamoate at
PCAS. Of the 50 intake samples collected, 14 (28%) samples screened NPS. The remaining 36
(72%) samples screened positive for intestinal parasites. In regards to positive samples; 33
(91.6%) screened positive for hookworms, 9 (25%) screened positive for whipworms, 6 (16.7%)
screened positive for round worms, including a single sample of bayliscorsasis. Co-infections
were found in 12 unique animals.
Of the 50 post-deworming samples 19 (38%) samples screened NPS. The remaining 31
(62%) samples screened positive for intestinal parasites. In regards to positive samples; 29
(93.5%) screened positive for hookworms, 10 (32.2%) screened positive for whipworms, 0 (0%)
screened positive for rounds worms, and 1 (3%) sample screened positive for tapeworms. Co-
infections were found in 12 unique animals.
The effectiveness of pyrantel pamoate at 10mg/kg as the sole deworming agent of dogs in
the shelter environment is not sufficiently effective in clearing all ova from stools 4 to 5 days
after deworming. In addition, the single use of pyrantel pamoate at time of intake fails to treat
occult whipworm infections. The failure to eliminate shedding of ova results in a highly
contaminated environment and chronic re-exposure of all kenneled animals, as well as staff,
volunteers, and adopters.
Although pyrantel pamoate displayed 100% clearance of all roundworm infections in this
study, varied levels of hookworm infections persisted. The failure of pyrantel pamoate to
completely eliminate hookworm ova from naturally infected animals appears significant.
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CHAPTER 4
DISCUSSION
In cases of most helminth infections, multiple dosing of appropriate anthelmintics are
strongly recommended in conjunction with environmental decontamination and concurrent
treatment of housemates in order to prevent recurrence of parasite infection. The sole use of
pyrantel pamoate for deworming of the canine population at PCAS fails to provide coverage for
prevalent whipworm species, fails to provide coverage for persistent infection via larval leak,
and fails to provide coverage for non-adult stages infection.
Of additional interest is the practical application of pyrantel pamoate in a high volume
shelter setting. The administration of pyrantel pamoate, in conjunction with vaccinations and
topical application of selamectin, occurs at time of admission. Animal control officers or animal
care technicians are generally responsible for application of these interventions. Unfortunately,
intake enrollment is an extremely stressful event for the animals and administration of the oral
medications can be especially challenging, with a high risk of under dosing or failure to medicate
at all. Elaboration of dosing concerns include; failure to appropriately weigh the animal resulting
in under dosages, difficulty administering large volumes of deworming agent, loss of medication
during administration, failure of animal to consume foods where medications are placed, and
failure to medicate fractious or bite quarantine animals. The difficulties of administering
medications are a recurring challenge in the shelter setting, and can significantly affect the
efficacy of our current deworming protocol.
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Ideally, an animal shelter-deworming agent would be inexpensive, highly palatable,
single dose, easy to administer, and have an extremely wide margin of safety. Several studies of
multidrug deworming medications have been analyzed in the scientific literature and show high
levels of efficacy against the 4 major intestinal parasites of zoonotic importance (excluding
protozoal organisms) roundworms, hookworms, tapeworms, and whipworms. Multiple studies
have been published, evaluating the efficacy of anthelminthic protocols. Multi drug approach to
anthelminthic treatment is often the most effective. (Lloyd & Gemmell, 1992) produced evidence
for the use of combination praziquantel, pyrantel embonate, and febantel against helminth
infections in dogs with naturally acquired infections. Based on the literature, treatment gave > 97
to 98% reductions in fecal egg counts attributable to Toxascaris leonina, T canis, and Uncinaria
stenocephala with efficacy against Trichuris vulpis at > 92%. Pyrantel pamoate, used in
conjunction with ivermectin as a monthly heartworm preventative gave 100% control of A.
braziliens (Shoop, Michael, Soll, & Clark, 1996) but was not analyzed for control of toxocara
species and is not labeled affective against whipworms or tapeworms. A comparative study
conducted by (Dryden & Ridley, 1999) highlighting pyrantel pamoate and fenbendazole in a
clinical setting showed Greyhounds administered fenbendazole had fecal egg count reductions
(FECRs) of 95.8 and 99.8% at 10 and 31 days following initial treatment, respectively.
Greyhounds administered pyrantel pamoate had FECRs of 85.8 and 88.3% at 10 and 31 days
after the first treatment, respectively. T. canis fecal egg counts conducted from Day 31 through
Day 128 were significant lower in those greyhounds administered fenbendazole as compared to
greyhounds administered pyrantel pamoate. This information highlights the range of efficiency
found in the clinical use of deworming agents. Rinaldi et al. performed a comparative study of
three combination drugs Milbemax® Drontal Plus Flavour® and , Nemex® POP for control of
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hookworms, roundworms, whipworms, and tapeworms. At Day -30 intestinal nematodes
(hookworms, Toxocara, Trichuris) and cestodes (Dypilidium caninum) were identified.
Milbemax® , a combination of milbemycin and praziquantel showed 100% efficacy against all
the helminths in all the kennels. Drontal Plus Flavour® , a combination of praziquantel, pyrantel
pamoate and febantel, was 100% effective against hookworms in all the kennels but gave lower
efficacy against T. canis (range#=#97.1-100%) and T. vulpis (range#=#95.6-100%). Nemex® POP,
combination of pyrantel pamoate, oxantel pamoate, and praziquantel was also 100% effective
against hookworms in all kennels but less effective against T. canis (range#=#95.7-100%) and T.
vulpis (range#=#95.7-100%). All three drugs were 100% effective against D. caninum. The use of
Febantel at 15mg/kg administered as a 3.4% paste completely cleared naturally infected dogs of
all nematode and cestode infections, including A. caninum, T. vulpis, Uncinaria stenocephala,
Toxocara canis, Toxascaris leonina, Taenia sp, and Dipylidium caninum. (Corwin, Mccurdy, &
Pratt, 1982).
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CHAPTER 5
RECOMMENDATIONS
Deworming Protocols
At this time the intake protocol for dogs at PCAS is based on a single deworming event
with pyrantel pamoate and topical application of selamectin ($9.54). The cost of this intervention
per 50lb dog is approximately $9.75. Based on my experiences at PCAS as staff veterinarian, and
looking at costs involved in treatment as well as dosing regimens I have the following
recommendations based on Table 1 and Table 2
Table 1: Drug Price Comparison Chart for a 50lb dog*
Trade Name Drug Name Dose frequency Cost Milbemycin + Lufenuron Sentinel Monthy $5.84 Milbemycin + Lufenuron + Praziquantel
Sentinel Spectrum Monthly $7.50
Ivermectin + Pyrantel pamoate Trihart Plus Monthly $3.48
Imidacloprid + Moxidectin Advantage
Multi Monthly $11.17 Fenbendazole Panacur 3 days $4.43 Epsiprantel Cestex Once Praziquantelv + Pyrantel + Febantel Drontal plus 1x and repeat $13.88 Febantel Rintal 3 days Pyrantel pamoate Strongid 1x and repeat $0.21 Spinosad + Milbemycin oxime Trifexis Once monthly $11.62 Nitenpyram Capstar as needed $3.18 Fipronil + (S)-methoprene Frontline Plus Monthly $10.81 Imidacloprid + Pyriproxyfen Advantage II Monthly $9.76 Selamectin Revolution Monthly $9.54
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*Pricing estimates based on quotes established 7/2015 by MWI Veterinary Supply Accounts
established with PCAS.
Table 1.2 Drug Comparison Chart
Trade Name Drug Name Route
Heart worm
Kills fleas
Round worm
Hook worm
Whip worm
Tape worm
Milbemycin + Lufenuron Sentinel oral + - + + + - Milbemycin + Lufenuron + Praziquantel
Sentinel Spectrum oral + - + + + +
Ivermectin + Pyrantel pamoate
Trihart Plus oral + - + + - -
Imidacloprid + Moxidectin
Advantage Multi topical + + + + + -
Fenbendazole Panacur oral - - + + + Epsiprantel Cestex oral - - - - - + Praziquantelv + Pyrantel + Febantel
Drontal plus oral - - + + + +
Febantel Rintal oral - - + + + - Pyrantel pamoate Strongid oral - - + + - - Spinosad + Milbemycin oxime Trifexis oral + + + + + - Nitenpyram Capstar oral - + - - - Fipronil + (S)-methoprene
Frontline Plus topical - + - - - -
Imidacloprid + Pyriproxyfen
Advantage II topical - + - - - -
Selamectin Revolutio
n topical + + - - - -
Intake Recommendations
• At time of intake animals 8 weeks and older shall be administered Trifexis
($11.62) for control of external and internal parasites.
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• In animals where oral dosing is not possible, topical use of Advantage Multi
($11.17) would be a reasonable intervention.
Based on the values of Table 11.2; treating a single 50lb dog at intake would cost
approximately $11.62 - $11.17. At this price point the control of parasites is excellent, with the
administration of a single or tablet given with a meal or a topical agent. Compliance with this
protocol by staff should be high, with a single agent given at time of admission. However,
emesis after administration of Trifexis is not an uncommon adverse reaction, and should factor
into decision making.
• Alternately, Sentinel Spectrum ($7.50) administered at time of intake with a
Capstar ($3.18) would control for external and internal parasites.
• In animals where oral dosing is not possible, topical use of Advantage Multi
($11.17) would be a reasonable intervention.
Based on the values of Table 11.2; treatment of a 50lb dog at time of intake would cost
approximately $10.68- $11.17. At this price point the control of parasites is good, but
compliance may decrease due to administration of two oral drugs.
Monthly Recommendations
Monthly external and internal parasite control should be included as an aspect of the
PCAS deworming protocol. Ideally parasite control should include heartworm prevention, flea
control, and intestinal parasite control.
• Sentinel flavor tabs ($5.84) administered monthly, with the addition of
Capstar ($3.18) as needed would be an ideal kennel treatment.
• Consider the use of Advantage Multi ($11.17) in animals where oral
mediation is not possible.
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Cost of monthly treatment per animal would range from $9.02 to $11.17 per 50lb animal.
• A less ideal, and more labor intensive, alternate protocol would involve the
use of ivermectin/pyrantel ($3.48) generic and fenbendazole ($4.43) as well as
a third flea control treatment. At intake all animals would be administered a
single dose of ivermectin/pyrantel generic and capstar ($3.18). Beginning on
day two of intake, medical staff would treat all new animals with 3 days of
fenbendazole.
The estimated cost per 50lb dog at time of intake would be $11.09. The entire herd would
be treated one monthly with ivermectin/pyrantel generic and fenbendazole, and flea control as
needed. Estimate cost of monthly parasite control would range from $7.91 to $11.09. The use of
fenbendazole as the deworming agent, although lower in price per animal, requires more labor of
veterinary services as well as increased risk of noncompliance. This protocol, although initially
more price competitive, is fraught with compliance issues and logistical challenges.
Adoptions Recommendations
• At time of adoptions, clients should be offered a purchase package of 3-month
supply of Sentinel or Trifexis, as well as a single dose of Capstar for control
of infectious parasitic agents.
The use of Sentinel or Trifexis for 3 months will cover for the lifecycle of whipworms
and prevent contamination of the new home environment and housemates with whipworms or
hookworms. The use of Sentinel or Trifexis will also control for any larval leak of hookworms
and roundworms. The single dose of Capstar will effectively kill adult fleas for a 24 to 48 hour
time frame, and break the tapeworm life cycle. By providing a post adoption package, for a
!19
reasonable fee, PCAS will be providing complete coverage for any infectious agents the adopted
animals may have been infected with while homeless or in the shelter environment.
Screening Recommendations
Monitoring of the prevalent helminth species in the shelter population is also a key aspect
of parasite control in the shelter setting. By monitoring our population on a regular basis, we can
note trends in helminth prevalence and well as evaluate the effectiveness of our protocols. The
regular sampling of the population also alerts the veterinary staffing to possible challenges in
compliance, drug efficacy, or possible shifts in parasite burdens in the population as a whole.
Environmental Control Recommendations
With access to so many effective deworming agents in the United States it would seem
that animal shelters should have the herd generally controlled with chemoprophylaxis. However,
animals found roaming and without medical care are often “unthrifty” and suffer from extremely
high worm burdens. In addition, the high rates of ova shedding results in extremely high rates of
parasitic exposure to all animals housed on the facility. Of particular concern as PCAS is the
continued use of dirt runs, grass play areas and grass lawns for dog walks, where
decontamination of sites is not possible. Removal of fecal material in individual and multi-use
areas is inconsistent at best. The subtropical climate of the Pasco Area also creates an idea
humid, moist environment for ova to mature. Desiccation from dry spells or challenges from
freezes do not occur at a level required to curtail parasite transmission. Pasco County’s climate
and location are generally ideal for the helminthes lifecycle. Ideally, dog runs and play areas
would be composed of concrete substrate, which are inhospitable to parasitic ova and larval
forms. Concrete structures may also be cleaned effectively with detergents and water, and be
fully decontaminated in instances of disease outbreaks. Alternate substrates include AstroTurf
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and gravel, both of which may be removed from the environment routinely as a part of sanitation
efforts. Removable substrates may also be replaced as needed during disease outbreaks or
quarantine efforts.
Client and Staff Education Recommendations
Controlling helminthic infections in pets is crucial to reduce infection risk for other
companion animals and to minimize public health hazards. Dissemination of understanding and
knowledge of transmission routes, at-risk categories and areas, and control methods are essential
to prevention efforts of humans and animals. Although virtually all of the majority of
roundworms and hookworms affecting dogs and cats may cause human diseases, the public risk
perception in general is poor.
It falls to the PCAS, as a public health agency, in conjunction with veterinarians, to
educate the public about zoonotic disease risk. The percentage of shelter animals examined by
veterinarians after adoption is unknown. However, it is possible to predict compliance based on
the socioeconomic status of the adopters. Educational and awareness interventions, generally at
the time of adoption, may be the only time a person will be exposed to messages regarding
zoonotic disease, basic hygiene, and deworming recommendations. Failure to provide basic
information regarding prevalent zoonotic diseases in shelter animals, especially parasitic
diseases, is a gross failure of the public health systems. Readily available zoonotic disease
pamphlets, verbal client education, and recommendations regarding continuous parasite control
are cost effective means of educating the public and providing the community with basic health
resources.
!21
Recommendations for Future Study
An anonymous staff survey evaluating compliance to current medical protocols as well as
barriers of compliance directed at all levels of staffing would greatly increase our understanding
of the barriers to work compliance found in the stressful shelter environment. A reassessment of
the current medical budget in light of public health concerns with higher levels of administration
including the ACA and additional stakeholders is absolutely necessary for the implementation of
a new deworming protocol. Multiple crossectional studies of parasite prevalence in the housed
population, as well as spot checks of nonclinical adopted animals will further reveal success and
failures in any deworming strategy PCAS implements. In a rapidly changing health environment,
where prevention of infectious diseases is a cornerstone of public health, consistent process
assessment, outcome assessment, and cost-benefit analysis will be necessary to keep the
homeless animals of Pasco County free from zoonotic infections and thereby reduce exposure of
said organisms to the general public.
Strengths of Study
The main strength of this study is in the analysis the efficacy of pyrantel pamoate in the
clinical settings of an animal shelter. This study is not created to argue the literature reviews,
which generally support the use of pyrantel pamoate as a safe and efficacious drug, but to
evaluate this medication in a high stress, high turnover, and highly disease endemic dog
population. This study is highly repeatable, cost effective, and requires no additional training for
veterinarians or veterinary staff.
Limitations Of Study
The current study, while shining a spotlight on ineffective public health practices at
PCAS, fails to address many of the underlying contributing factors. Limitations of this study
!22
include the lack of specification of parasite species based on microscopic analysis, failure to
include ectopic parasites, protozoal organisms and heartworm status of animals in order to
produce a complete profile of parasite burden. In addition, the use of fecal ova reduction counts
instead of binary data would have provided greater insight into the efficacy of the anthelminthic
agents. Statistical analysis of data was not included. The study design also fails to clarify the
cause of outcome. We cannot determine if failure of anthelminthic agent, failure in staff
compliance, or both factors contributes to the study outcome.
!23
Chapter 6
CONCLUSION
In summary, an economical and evidence –based deworming protocol is an essential
component of PCAS’s success as a public health facility. However, the importance of continued
environmental control paired with ongoing staff and volunteer education cannot be ignored.
Finally, providing educational materials to all potential adopters about zoonotic agents found at
PCAS in conjunction with opportunities to continue treatment of prevalent diseases via the
purchase of effective medication will positively impact the health of our human and companion
animal community.
!24
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