Internal helminth parasites are potential causes of primary disease in dogs and cats and zoonotic diseases in humans. Canine and feline parasite surveys frequently list roundworms (Toxocara canis, Toxocara cati, Toxascaris leonina) and hookworms (Ancylostoma caninum, Ancylostoma tubaeforme, Ancylostoma braziliense, Uncinaria stenocephala) as common helminths. Numerous anthelmintics, representing several chemical classes, are available for treatment and control of canine and feline roundworm and hookworm infections.

1. A NEWSLETTER OF PRACTICAL MEDICINE FOR VETERINARY PROFESSIONALS
DECEMBER 2004 VOLUME 2, NUMBER 4
Roundworms, Hookworms,
and Pyrantel Pamoate
Byron L. Blagburn
Distinguished University Professor
Department of Pathobiology
College of Veterinary Medicine
Auburn University
Internal helminth parasites are Among them are the benzimidazoles T. leonina can infect both dogs and cats.
potential causes of primary disease in dogs (fenbendazole), the macrocyclic lactones Both T. canis and T. cati usually undergo
and cats and zoonotic diseases in humans. (ivermectin, milbemycin oxime), the hepatotracheal migration before becoming
Canine and feline parasite surveys tetrahydropyrimidines (pyrantel pamoate), established in the small intestine. In older
frequently list roundworms (Toxocara and the heterocyclic compounds dogs and cats, a greater number (but not
canis, Toxocara cati, Toxascaris leonina) and (piperazine). Pyrantel pamoate has treated all) of migrating larvae are diverted to
hookworms (Ancylostoma caninum, roundworm and hookworm infections extraintestinal tissue. T. leonina does not
Ancylostoma tubaeforme, Ancylostoma safely and effectively for many years. undergo extraintestinal migration. The
braziliense, Uncinaria stenocephala) as Specific knowledge of both parasites and time from exposure to the parasite until
common helminths. Numerous parasite control products is essential for mature worms are present in the intestine
anthelmintics, representing several successfully controlling parasitic diseases
chemical classes, are available for and preventing their transmission to
treatment and control of canine and feline humans. This article reviews the behavior IN THIS ISSUE:
roundworm and hookworm infections. of common canine and feline ascarids and Roundworms, Hookworms,
hookworms, as well as the properties of and Pyrantel Pamoate................. 1
pyrantel pamoate.
The American Kennel Club
ROUNDWORMS Welcomes Two New Breeds ...... 5
Roundworms affecting dogs and cats
(T. canis, T. cati, T. leonina) are large (up to Ask the Vet ................................ 7
4.5 inches), stout worms that live as adults Hartz Mountain Partners
Figure 1— Toxocara canis (on in the lumen of the small intestine (Figure with the AKC to
bottom) and Dipylidium caninum 1). T. canis are commonly found in dogs, Benefit Veterinarians ................. 8
from a dog’s intestine. while adult T. cati are restricted to cats.

2. A NEWSLETTER OF PRACTICAL MEDICINE FOR VETERINARY PROFESSIONALS
DECEMBER 2004 VOLUME 2, NUMBER 4
Consulting Editors
Albert Ahn, DVM
Corporate Vice President
Figure 4— Ancylostoma caninum Chief Scientific Officer
from a dog’s intestine.
The Hartz Mountain Corporation
Bruce Truman
completely effective in parasitic elimination.
Figure 2— Unembryonated egg T. canis is important because of its Divisional Vice President
of Toxocara canis from dog feces. ability to produce primary disease in dogs Animal Health and Nutrition
as well as several extraintestinal disease The Hartz Mountain Corporation
syndromes known as larva migrans in
many hosts, including humans. When HARTZ® COMPANION ANIMALSM
ingestion of embryonated eggs (Figure 3) is produced for The Hartz Mountain
results in migration and damage to Corporation by Veterinary Learning
internal organs, the syndrome is referred Systems, 780 Township Line Rd.,
to as visceral larva migrans (VLM). VLM Yardley, PA 19067.
is observed most often in children
Copyright © 2004 The Hartz Mountain
younger than 3 years of age. Encysted Corporation. All rights reserved.
larvae induce nodules in such organs as
the liver, lungs, kidney, and brain. These Hartz® and other marks are owned by
infections generally manifest as profound The Hartz Mountain Corporation.
eosinophilia, pneumonitis, and
Figure 3— Embryonated egg of Printed in U.S.A. No part of this
Toxocara canis from a public park. hepatomegaly. In older children (generally
3 to 13 years), the larvae apparently have a publication may be reproduced in any
more pronounced predilection for the form without the express written
varies based on the infection route but is posterior chamber of the eye. The permission of the publisher.
generally 2 to 5 weeks. resulting granulomatous retinitis is the For more information on The Hartz
Recent surveys show that T. canis and T. hallmark of this second syndrome, known Mountain Corporation, visit
cati remain prevalent in pets. One survey of as ocular larva migrans (OLM). OLM can www.hartz.com.
6,458 dogs from U.S. shelters indicated that result in severe ocular damage and
T. canis eggs (Figure 2) were present in the subsequent retinal detachment, loss of
feces of almost 15% of the sample vision, and even blindness. Interestingly, environmental conditions, can increase
population. Although the prevalence was OLM can occur in the complete absence exposure and infection risks to both pets
less in adult dogs, the survey results indicate of eosinophilia and signs or evidence of and humans.
that T. canis is not restricted to puppies. VLM. Although T. cati is thought to be
Regardless of geographic location, T. less-often associated with these HOOKWORMS
canis is a common parasite of dogs because syndromes, recent research indicates that Hookworms are small (up to about
there are several routes for potential it, too, can cause them. 0.75 inch), whitish or reddish-brown
infection. These include embryonated eggs Adult female roundworms are prolific worms with hooked anterior ends (hence
(Figure 3), transplacental transmission, egg producers. For example, T. canis females the name). Adults reside in the small
transcolostral transmission (less common are estimated to produce between 25,000 intestine of dogs or cats (Figure 4).
for T. canis), and ingestion of transport and 85,000 eggs/day while T. cati females Ancylostoma spp include A. caninum (the
hosts such as rodents and rabbits. can produce between 19,000 and 24,000 universally distributed canine hookworm),
Transplacental transmission accounts largely eggs/day. Given these egg-production rates, A. tubaeforme (the feline hookworm), and
for the prevalence of T. canis in neonatal it is easy to see how environments can A. braziliense (found in both dogs and cats
and juvenile dogs. Although age-associated eventually harbor large numbers of eggs. in the subtropical United States). In the
immunity aids in the expulsion of some T. Parasite reproductive rates, combined with aforementioned survey, almost 20% of
canis adults as dogs mature, it is not resistance of embryonated eggs to adverse 6,458 fecal samples from shelter dogs
2 HARTZ COMPANION ANIMAL
® SM
• DECEMBER 2004 • VOL. 2, NO. 4

3. HO2C OH
N
CH CH CH2
S
N
CH3
2
Figure 5— Unembryonated eggs Figure 7— Chemical structure of pyrantel pamoate (embonate).
of Ancylostoma caninum from dog
feces.
transmammary route of infection can lead pamoate (also called pyrantel embonate;
to the establishment of very high worm Figure 7) is the derivative currently
burdens in neonatal dogs in a short time. marketed in several formulations for use
The remaining species are less significant in dogs and cats (Table 1). It is poorly
but not always innocuous pathogens. absorbed from the stomach and intestine
A. caninum, similar to T. canis, is a prolific following oral administration. Between
egg producer. It is estimated that mature 50% and 70% of pyrantel pamoate appears
A. caninum females can produce up to unchanged in feces, which accounts for its
Figure 6— Severe hookworm 20,000 eggs/day, resulting in substantial efficacy and safety (it does not enter the
disease caused by Ancylostoma environmental reservoirs of infective blood system). Pyrantel pamoate is found
tubaeforme in a cat. larvae in a rather short period. in the blood of treated animals at a rate of
Free-living infective larvae of some less than 1 µg/ml of blood. Another
yielded A. caninum eggs. A single Ancylostoma spp may penetrate human benefit of poor absorption is that efficacy
Uncinaria species (U. stenocephala) occurs skin and subsequently migrate for brief is enhanced because pyrantel pamoate
in dogs (but rarely in cats) living in periods, causing reddish, pruritic, remains in contact with the parasites
temperate regions worldwide. serpentine lesions. This condition is targeted for removal.
The hookworm developmental cycle referred to as cutaneous larva migrans Pyrantel pamoate kills parasites by
includes a free-living phase in which larvae (CLM) or creeping eruption. Although attacking their nervous system, resulting
hatch from eggs (Figure 5) and develop less significant than the larva migrans in irreversible paralysis of the parasite’s
through three distinct stages. The third syndromes caused by roundworms, the musculature. This is important because
environmental larval stage (infective stage) hookworm-related cutaneous syndrome parasites can recover from brief exposure
enters the host by either oral ingestion or remains a concern for veterinarians and to other parasiticides but not from
skin penetration. Most (but not all) orally pet owners. A. braziliense larvae appear to exposure to pyrantel pamoate. When
ingested larvae establish in the intestine be the most common cause, although dogs and cats are allowed to eat before
without extraintestinal migration. Those cases of A. caninum– and U. stenocephala– treatment, the passage of pyrantel
that penetrate the skin follow a vascular or induced CLM have been documented. pamoate through the intestinal tract is
pulmonary migration before becoming slowed, permitting prolonged contact time
established in the small intestine. In PYRANTEL PAMOATE: with parasites and thus increasing efficacy.
addition, both prenatal (transplacental) CHEMICAL PROPERTIES, Pyrantel pamoate is available as a
and transmammary transmission can EFFICACY, AND SAFETY flavored suspension, tablet, or chewable
occur. The reservoir for such larvae is Pyrantel salts have been used tablet (Table 1). It is 95% effective against
somatic, as is the case with T. canis. effectively for parasite control for almost ascarids (T. canis, T. leonina) and
Hookworms may cause dermal, four decades. Although initially hookworms (A. caninum, U. stenocephala) in
pulmonary, and intestinal diseases (Figure introduced to control sheep parasites, dogs at a dose of 5 mg/kg. Because efficacy
6). The latter is most common in dogs. subsequent formulations were produced might be decreased in puppies weighing
In young dogs, A. caninum–related for cattle (not currently FDA approved), less than 2.2 kg, a dose of 15 mg/kg
hemorrhagic enteritis can be a peracute, swine, horses, dogs, and cats. Pyrantel is a given 30 minutes after a light meal is
life-threatening disease. The tetrahydropyrimidine compound. Pyrantel recommended. Pyrantel pamoate may be
HARTZ® COMPANION ANIMALSM • DECEMBER 2004 • VOL. 2, NO. 4 3

4. TABLE 1: Examples of Parasite Control Products Containing Pyrantel Pamoate
Product Name Host Species Formulation Ingredients Target Parasites
D-Worm 60, D-Worm Dogs Chewable Pyrantel pamoate Toxocara canis, Toxascaris leonina, Ancylostoma
120 (Farnum) tablet caninum, Uncinaria stenocephala
Hartz® Rid Worm™ Dogs Chewable Pyrantel pamoate Toxocara canis, Toxascaris leonina, Ancylostoma
(Hartz) tablet caninum, Uncinaria stenocephala
Nemex Tabs, Nemex-2 Dogs Tablet/ Pyrantel pamoate Toxocara canis, Toxascaris leonina, Ancylostoma
Suspension (Pfizer) Suspension caninum, Uncinaria stenocephala
Heartgard Plus (Merial) Dogs Chewable Pyrantel pamoate, Toxocara canis, Toxascaris leonina, Ancylostoma
tablet ivermectin caninum, Ancylostoma braziliense, Uncinaria
stenocephala, Dirofilaria immitis
Iverhart Plus (Virbac) Dogs Chewable Pyrantel pamoate, Toxocara canis, Toxascaris leonina, Ancylostoma
tablet ivermectin caninum, Ancylostoma braziliense, Uncinaria
stenocephala, Dirofilaria immitis
Tri-Heart Plus Dogs Chewable Pyrantel pamoate, Toxocara canis, Toxascaris leonina, Ancylostoma
(Schering Plough) tablet ivermectin caninum, Ancylostoma braziliense, Uncinaria
stenocephala, Dirofilaria immitis
Drontal (Bayer) Cats Tablet Pyrantel pamoate, Toxocara cati, Ancylostoma tubaeforme, Taenia
praziquantel spp, Diplydium spp
Drontal Plus (Bayer) Dogs Tablet Pyrantel pamoate, Toxocara canis, Toxascaris leonina, Ancylostoma
praziquantel, caninum, Uncinaria stenocephala, Trichuris vulpis,
febantel Taenia spp, Diplydium spp, Echinococcus spp
combined with other compounds (e.g., bitches and queens before they whelp or spectrum of activity. Few anthelmintics
ivermectin, febantel, praziquantel) to queen reduces the number of eggs shed have retained their utility and widespread
prevent heartworm infection and eliminate into the environment, which in turn use in the companion animal market for
tapeworms and whipworms as well as decreases the challenge rate from 40 years. Continued success of pyrantel
ascarids and hookworms (Table 1). environmental eggs and larvae. pamoate is testimony to its safety,
Formulations containing ivermectin and However, most ascarid and efficacy, and convenience.
pyrantel pamoate are available as chewable hookworm infections are acquired
tablets and are effective against A. either transplacentally or via milk and SUGGESTED READING
braziliense. Though pyrantel pamoate is not colostrum. Pyrantel pamoate is approved Blagburn BL, Lindsay DS, Vaughan JS, et al: Prevalence
of canine parasites based on fecal flotation. Compend
approved for use in cats as a stand-alone for use in puppies as young as 2 weeks of Contin Educ Pract Vet 18:483–509, 1996.
product, it is used safely and effectively in age. This, too, is important because Clark JN, Daurio CP, Barth DW, Batty AF: Evaluation
cats at a dose of 20 mg/kg. Pyrantel treating puppies regularly at a very early of a beef-based chewable formulation of pyrantel
pamoate against induced and natural infections of
pamoate is combined with praziquantel in age (i.e., at 2, 4, 6, and 8 weeks) can both hookworms and ascarids in dogs. Vet Parasitol
a tablet formulation for removal of ascarid prevent acute ascarid- and hookworm- 40:127–133, 1991.
(T. cati), hookworm (A. tubaeforme), and related disease and reduce or eliminate Lynn RC: Antiparasitic drugs, in Bowman DD (ed):
tapeworm infections (Table 1). the shedding of ascarid and hookworm Georgis’ Parasitology for Veterinarians, ed 8.
Philadelphia, WB Saunders, 2003, pp 244–286.
The safety of pyrantel pamoate is eggs in feces. The latter is important in
Nolan TJ, Hawdon JM, Longhofer SL, et al: Efficacy of
exceptional. The toxic dose in dogs preventing the transmission of ascarids an ivermectin/pyrantel pamoate chewable
exceeds the therapeutic dose by almost and hookworms from pets and their formulation against the canine hookworms Uncinaria
stenocephala and Ancylostoma caninum. Vet Parasitol
140 times. Pyrantel pamoate can be environments to humans. 41:121–125, 1992.
administered to dogs at four times the In summary, pyrantel pamoate is Reinemeyer CR, Courtney CH: Antinematodal drugs, in
recommended dose daily for up to 3 among the safer and more effective Adams HR (ed): Veterinary Pharmacology and
months without inducing adverse events. anthelmintics for removing ascarids and Therapeutics, ed 8. Ames, Iowa State University
Press, 2001, pp 947–979.
Another safety attribute is that it can be hookworms from dogs and cats. It is
Vanden Bossche H, Theinpont D, Janssens PG (eds):
safely administered to pregnant animals. available in convenient formulations and Chemotherapy of Gastrointestinal Helminths. New
This is important because deworming combination products, which extends its York, Springer-Verlag, 1985.
4 HARTZ COMPANION ANIMAL
® SM
• DECEMBER 2004 • VOL. 2, NO. 4

5. The American Kennel Club Welcomes
Two New Breeds
I
n the ever-changing landscape of companion animal ownership,
it can often be challenging to discern just what that furry
quadruped is on the other end of a client’s leash. As of May 1,
2004, The American Kennel Club (AKC) officially recognizes 152
breeds of dogs within seven groups: Sporting, Hound, Working,
Terrier, Toy, Non-Sporting, and Herding. Counting nine breeds Neapolitan
that are divided into varieties (a division of a breed based on coat, Mastiff
color, or size), the grand total of distinct breeds that are eligible to
compete for championship points at AKC shows climbs to an
impressive 164 breeds and varieties. Newest to join the ranks of the reliable.” Black Russian Terriers thrive in every clime, from the
Working Group are two formidable breeds: the Black Russian Arctic to Australia. The breed’s tousled, double coat is not known
Terrier and the Neapolitan Mastiff. to shed profusely. Grooming fashions for this dog may call to
The Black Russian Terrier (below) is a relatively new breed mind the Bouvier or the Giant Schnauzer, but the Black Russian
created in the 1930s in the then Soviet Union to meet the need Terrier is unmistakably a breed unto itself.
for security dogs. The main crosses of the breed’s development The Neapolitan Mastiff (above) is an ancient breed dating
were made among Giant Schnauzers, Rottweilers, and Airedale from the time of Alexander the Great. Also known as the
Terriers. The Black Russian Terrier also bears traces of “Mastino,” he is a heavy-boned, massive dog bearing loose skin all
Newfoundlands, Great Danes, and several Russian breeds, such as over the body, abundant wrinkles and folds on the head, plus a
the Ovcharka. Once known as the Black Pearl of Russia, the voluminous dewlap. Referenced in the works of Greek and Latin
“Blackie” is a loyal companion and loving pet, a nimble black flash writers and artists, the ancient molossus developed by Alexander
on the agility course, a keen-witted obedience dog, and a guardian the Great is believed to be the forefather of the modern
without peer. Mature dogs measure between 27 and 30 inches, Neapolitan Mastiff. While the molossus was used to fight tigers,
while mature bitches are between 26 and 29 inches. According to lions, elephants, and men in battle, today’s Mastino is a calm,
breed experts, elbows and hips are the breed’s only significant docile creature—not a fighting dog. Breed lore holds that the
health issues. The breed standard describes the temperament: “The dog’s unique type was developed purposely as an alarmingly ugly
Black Russian Terrier is a calm, confident, and dog whose looks alone were enough to intimidate any intruder.
courageous dog with a self-assurance which is Fanciers of the breed report that Neapolitan Mastiffs are
sometimes rather aloof toward strangers. They courageous but not aggressive, wary yet approachable. In addition
are highly intelligent, to considering its massiveness (average weight of mature dogs is
(and) extremely 150 lb), potential owners must also take into account the breed’s
tendency to drool and a distinctive odor characterized as a
“woodsy” smell. Clients seeking a canine jogging partner should
look elsewhere, as the Mastino was not bred for endurance.
FREE POSTER OFFER
Consult the Hartz/AKC Guide to Purebred Dogs poster to see
these new breeds within the context of the American purebred
universe. To obtain a free copy for your office, call the Hartz
Consumer Affairs Department at 1-800-275-1414,or email us
at feedback@hartz.com. Call today; quantities are limited.
Black Russian Terrier
HARTZ® COMPANION ANIMALSM • DECEMBER 2004 • VOL. 2, NO. 4 5

7. Albert Ahn, DVM, is a veterinarian, Corporate Vice President, and
Chief Scientific Officer of The Hartz Mountain Corporation.
ASK TH E VET
Q Can pyrantel pamoate be used in
pregnant or nursing animals? Q What types of products should be
included in a home dental care routine?
A Pyrantel pamoate, a pyrimidine anthelmintic, is
commonly used to treat and prevent hookworm
(Ancylostoma caninum, Uncinaria stenocephala) and
A In addition to regular veterinary examinations and
teeth cleaning, home dental care is an important
part of maintaining a pet’s oral health. Studies show
ascarid (Toxocara canis, Toxascaris leonina) infestation that brushing a dog’s teeth on a regular basis is the
in dogs. Pyrantel causes paralysis in susceptible best method of removing plaque and preventing its
parasites through neuromuscular blocking effects. buildup.
According to veterinary pharmacology references,
pyrantel is considered safe to use during pregnancy Rawhide dog treats have been used for many years
and in nursing animals. to satisfy a dog’s natural chewing needs. The
abrasive action of rawhide chewing also helps
Q How will Hartz be observing Pet Dental
Month in February?
reduce plaque and calculus. Hartz® Dental™
Flavor Infused™ Chew-Dent™ chews are made
through a patented process that allows flavor to
A To help celebrate Pet Dental Month, Hartz has
created a dental care brochure for pet owners that
details the many benefits of regular veterinary visits,
permeate throughout the beef hide. Dogs chew
longer, helping to remove plaque up to 54% and
tartar up to 68%.
teeth cleaning, and home dental care. Hartz will also
be giving away sample packs of Hartz Breath Strips. Chew toys are another option. Most have raised tips
To order brochures and breath strips for your clinic, that massage gums and help decrease plaque
you can call the Hartz Consumer Relations buildup. They also provide the necessary chewing
Department at 800-275-1414 or email exercise to strengthen gums as well as providing
feedback@hartz.com. relief from boredom, frustration, or anxiety.
Articles found in the Hartz Companion Animal SM newsletter can be copied and distributed to your colleagues, staff, and clients.
Additional newsletters may also be obtained by contacting us at feedback@hartz.com or by phone at 800-275-1414.
WE WANT TO HEAR FROM YOU!
• Have questions or comments? Call our Consumer Relations Department at 800-275-1414 and ask to speak to a Hartz staff
veterinarian or email us at feedback@hartz.com.
• To obtain a Hartz Veterinary Catalog of products, please call 800-999-3000 x5118 or email us at feedback@hartz.com.
HARTZ® COMPANION ANIMALSM • DECEMBER 2004 • VOL. 2, NO. 4 7

8. Hartz Mountain Partners with
The AKC to Benefit Veterinarians
This summer, The Hartz Mountain Corporation became the two organizations that brought the “DOGNY Help a Hero”
the official sponsor of The American Kennel Club’s Veterinary toy series to market. Hartz’ sales of the popular dog toy, bearing
Outreach Program. Uniting the world of purebred dogs with the likeness of real-life search and rescue dogs, have contributed
the veterinary community, the program offers resources in sup- over $1 million to the AKC CAR Canine Support and Relief
port of veterinary students, practitioners, and researchers, creat- Fund to support professional and volunteer canine search and
ing a forum for the exchange of information about canine health rescue organizations throughout the United States.
and welfare and providing scholarships for future practitioners AKC President Dennis B. Sprung stated, “The AKC is
and researchers. delighted to be working with The Hartz Mountain Corporation
“The Hartz Mountain Corporation values its relationship on the many programs that heighten the appreciation and
with the veterinary community as evidenced by the creation of awareness of the role that dogs play in our lives, whether they
the Veterinary Outreach Program,” said Albert Ahn, DVM, be search and rescue dogs, working service dogs, show dogs,
Corporate Vice President and Chief Scientific Officer at Hartz. or household pets. Now, their sponsorship of the Veterinary
“We are committed to providing high-quality pet products and Outreach Program allows us to bring a greater level of support
celebrating the human–animal bond.” to the professionals who uphold the human–animal bond—our
The sponsorship of the AKC’s Vet Outreach Program by current and future veterinarians, veterinary researchers, and vet-
Hartz comes on the heels of a very successful venture between erinary technicians.”
Veterinary Learning Systems PRESORTED STANDARD
780 Township Line Road U.S. POSTAGE
Yardley, PA 19067
PAID
BENSALEM, PA
PERMIT #118
400861