K9FORCE | FEBRUARY 2025
These worms are spaghetti-like in their appearance, and infection
occurs when dogs come in contact with eggs from the parasite. In
some cases, roundworms migrate away from the gastrointestinal tract
encyst and then lay dormant in muscle and mammary tissue. This
becomes a risk for puppies to contract this parasite shortly after birth as
they become active shortly after whelping due to a drop in the dam's
immunity, allowing them to be passed on to the puppies when nursing
—making deworming protocols essential for young dogs! Medications
used to treat these parasites include pyrantel pamoate, fenbendazole
and macrocyclic lactones.
An Explanation of Veterinary Anti-Parasitic
Hookworms are common across North America, especially in regions
with warm to moderate climates. Adult hookworms live in the small
intestines, where they attach to the wall of the intestine and consume
blood. If left untreated, it will eventually cause clinical signs associated
with blood loss, anemia, weight loss, dry coat and tarry diarrhea.
Similar to the roundworms, these parasites can be transferred to
puppies at nursing.
The last group of parasites to discuss are the intestinal parasites, which
include roundworms, hookworms and tapeworms. Roundworms are
one of the most common intestinal parasites, and it has been estimated
that 80% of newborn puppies in the United States will be infected at
birth.
Intestinal Parasite Prevention
As one can imagine, having a heavy load of these parasites within the
heart and its vasculature can result in chronic coughing, difficulty
breathing, edema of the limbs and abdomen, fluid accumulation in the
chest, weakness, exercise intolerance and collapse. Treatment is
complex and expensive and requires the use of melarsomine, an
arsenic derivative, to treat the infection. Therefore, early treatment
before larvae reach maturity through preventative medication is the
easiest and most cost-effective option.
The medication used is under the drug class macrocyclic lactones,
which includes products such as ivermectin, milbemycin and
moxidectin. The main formulations are available as a monthly oral
chewable (Heartgard®, Interceptor®, etc.) or as a long-lasting
injection (ProHeart®). Macrocyclic lactones work by disrupting the
parasite's nerve and muscle cells, resulting in paralysis and eventual
death.