Ancylostoma Caninum: The Canine Hookworm and Its Economic Impact

Ancylostoma caninum, also known as the canine hookworm, is a parasite that affects dogs worldwide. It's a significant problem in many regions, particularly in tropical and subtropical areas.

The parasite is usually acquired through contact with contaminated soil, feces, or the vomit of an infected dog. This often happens when a dog walks on contaminated ground or licks its paws after coming into contact with the parasite.

Ancylostoma caninum larvae can penetrate the dog's skin, causing an allergic reaction and leading to severe itching and skin irritation. This can be a painful and uncomfortable experience for the dog.

The economic impact of Ancylostoma caninum is substantial, with estimates suggesting that it costs the global dog population over $2 billion annually.

Ancylostoma caninum females are typically 14–16 mm long and 0.5 mm wide, while males are smaller at 10–12 mm in length and 0.36 mm in width.

The unique feature of A. caninum is its copulatory bursa, which consists of spine-like spicules positioned on three muscular rays that grasp the female during mating.

A different take: Ancylostoma Caninum Common Name

Males have a copulatory bursa, which is a useful means for identifying members of the Strongylida suborder and distinguishing between species within the suborder.

The vulva of A. caninum females is located at the boundary of the second and final thirds of the body.

The teeth of A. caninum are found in the buccal capsule and divided into three sets, with the ventral sets forming a lower-jaw equivalent and a dorsal set projecting from the dorsal side.

A. caninum bends its head end upward, which can be a potential source of confusion when determining how the hookworm is oriented.

A. caninum has an alimentary canal made up of an esophagus, intestine, and rectum, with the esophagus being highly muscular to pull intestinal mucosa into the body when it feeds.

Eggs are laid by the females, typically when at the eight-cell stage, and are 38–43 μm in width with thin walls.

In an environment of 23 degrees Celsius, the egg hatches into the first-stage juvenile in the soil in approximately one day.

The cuticle is molted twice and the infective third-stage juvenile emerges within four to five days.

As we dive into the world of morphology and development of gastrointestinal nematodes, it's essential to understand the current state of anthelmintic resistance in dogs.

Anthelmintic resistance among canine hookworms, specifically Ancylostoma caninum, is a growing concern in the USA, and it's likely to affect Canada as well.

The development of anthelmintic resistance in A. caninum is mainly driven by the arrival of resistant isolates via animal importation, primarily from the USA.

There are numerous anthelmintic formulations available in Canada for dogs, including single, double, and triple combinations of drug classes against helminths.

Many of these formulations also include a compound to treat arthropod parasites, which can be beneficial for dog owners.

The historical high efficacy of anthelmintic classes such as benzimidazoles (BZs), macrocyclic lactones (MLs), and pyrantel against gastrointestinal nematodes in dogs is a reassuring fact.

However, the emerging resistance among A. caninum in dogs highlights the need to verify the efficacy of current anthelmintic formulations in Canada.

Curious to learn more? Check out: Toxocara Canis Treatment in Dogs

A. caninum females are typically 14–16 mm (0.55–0.63 in) long and 0.5 mm (0.02 in) wide, while the males are smaller at 10–12 mm (0.39–0.47 in) in length and 0.36 mm (0.01 in) in width.

The males have a distinctive copulatory bursa, which consists of spine-like spicules positioned on three muscular rays that grasp the female during mating.

This unique feature is a key identifier for members of the Strongylida suborder, and it's also used to distinguish between species within the suborder.

A. caninum bends its head end upward (dorsally), which can be a potential source of confusion when determining how the hookworm is oriented.

If it has recently ingested blood, A. caninum is red in colour; if not, it appears grey.

The teeth of A. caninum are found in the buccal capsule and divided into three sets, with two ventral sets forming a lower-jaw equivalent and a further set projecting from the dorsal side.

Each ventral set has three points, with those furthest to the sides being the largest.

The vulva of A. caninum females is located at the boundary of the second and final thirds of the body.

Eggs are laid by the females at the eight-cell stage, typically when they are 38–43 μm in width, with thin walls.

The development of Ancyclostoma caninum is quite fascinating. The eggs of this parasite can hatch into the first-stage juvenile in just one day in an environment of 23 degrees Celsius.

This first-stage juvenile will molt twice within four to five days, emerging as the infective third-stage juvenile. The cuticle is shed each time, allowing the parasite to grow.

Infection can occur through ingestion or penetration of the unbroken skin. Either way, the parasite ends up in the small intestine of the host.

If ingested, A. caninum travels to the stomach, molts, migrates to the small intestine, molts a fourth and final time, and develops to maturity in about 5 weeks. This process is quite remarkable.

If entrance is via the skin, A. caninum makes its way through the dermal layers and enters the circulatory system, which takes it to the lungs. From there, it travels up the trachea and is swallowed.

Copulation occurs within the small intestine, and the female worms pass eggs in the feces. This is the final stage of the parasite's life cycle.

Transplacental and transmammary transmission are known for dogs infected with A. caninum. This means the parasite can be passed from mother to offspring during pregnancy or nursing.

Occasionally, an A. caninum juvenile will penetrate the skin of a human but cannot complete its life cycle in the inappropriate host. It will wander about in the upper layers of the skin, causing a condition called dermal larva migrans.

For another approach, see: Toxocara Canis Life Cycle

Ancylostoma caninum, the parasite responsible for causing hookworm infections, has a unique life cycle that involves transmission through the environment and habitat. This parasite is typically found in warm, moist climates, where it can thrive in a variety of habitats.

In the wild, Ancylostoma caninum larvae are excreted from the host in the feces and hatch within a day on moist, warm soil. The first larval stage lives in the soil where it molts twice and then emerges into its infectious third stage.

The third stage juvenile can enter the host through two routes: by direct ingestion of the parasite or by penetration of skin at hair follicles or sweat glands. The larvae then migrate through the dermis of the skin, enter the circulatory system, and are carried to the lungs.

If ingested, the third stage juvenile goes through the stomach and ends up in the small intestine, where it can feed on mucosa and blood of the small intestinal wall. The parasite is attracted to the host's mucosa and blood by a receptor-mediated response.

Ancylostoma caninum is found in various regions, including temperate, tropical, and terrestrial biomes. It inhabits habitats such as desert or dune, savanna or grassland, chaparral, forest, rainforest, scrub forest, and mountains.

Here are some specific regions where Ancylostoma caninum is found:

The rate of infection is temperature dependent, with temperate and warm climates being optimal conditions for the parasite to thrive.

As A. caninum larvae migrate through the skin, they often stimulate an inflammatory response, causing dermatitis, which can be exacerbated in hosts with hypersensitive responses.

The larvae's migration through the skin can leave a wound vulnerable to secondary infections.

A. caninum larvae enter the lung, causing damage that can lead to pneumonia and coughing.

In the gut, A. caninum attaches to and ingests the mucosal lining, compromising the body's defenses.

This damage can result in secondary infections by microbes.

A. caninum feeds from up to six sites in a 24-hour period, consuming up to 0.1 ml of blood.

The anticoagulant proteins called A. caninum anticoagulant proteins (AcAPs) help in the feeding process by preventing clotting and increasing blood loss.

These AcAPs are among the most powerful natural anticoagulants that exist.

Blood losses peak just prior to egg production by the females because their requirements for food are greatest during this time.

Maximal damage to the intestine is caused when the females are eating the most.

Take a look at this: Flea Larvae on Dog

Diagnosis of ancylostoma caninum infection is confirmed through microscopic analysis of a dog's faeces, where characteristic ovular, thin-shelled eggs are present.

Faeces sampling is the definitive method, but absence of eggs doesn't rule out infection, as a delay of at least 5 weeks exists between initial infection and egg excretion.

Signs of infection include lethargy, weight loss, and roughness of the hair coat, often accompanied by pale mucous membranes and black stools due to blood-derived haemoglobin.

Diagnosis can be challenging, especially in well-fed, older dogs with smaller infestations, which may present few or no symptoms.

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Diagnosis of Ancylostoma caninum infection is confirmed through the analysis of faeces, specifically looking for the characteristic ovular, thin-shelled eggs of the parasite.

The eggs are usually found microscopically in the faeces, but it's essential to note that absence of eggs does not rule out infection. It can take at least 5 weeks for the larvae to mature and reproduce, allowing eggs to be laid.

For your interest: Dog Flea Eggs Look like

Signs and symptoms of the infection include lethargy, weight loss, weakness, roughness of the hair coat, and pale mucous membranes indicative of anemia.

Diarrhoea is rare, but stools are typically black due to the presence of blood-derived haemoglobin.

Well-fed, older dogs with smaller infestations may show few or no symptoms.

Vaccination is a promising approach to combating A. caninum infections.

Numerous vaccines have been developed, but not all have been successful.

One vaccine uses an enzyme called AcCP2, which is important in the worm's feeding process. This vaccine gives a strong antibody response and reduces worm numbers and size in dogs.

A similar approach using another enzyme called AcGST1 didn't give the same results.

Using the AcASP1 protein of A. caninum has been successful in disrupting the worm's migratory ability. This results in increased antibody levels and a reduced worm burden.

Animals with prior exposure to A. caninum show enhanced resistance to the infection.

Diagnosis and treatment of A. caninum infections in dogs require a combination of medication and care.

The first step in treating A. caninum infections is to administer medication.

Drugs such as dichlorvos, fenbendazole, flubendazole, and mebendazole are commonly used to treat these infections.

These medications work by targeting the worms and killing them, thus eliminating the infection.

Other medications like nitroscanate, piperazine, pyrantel, and milbemycin can also be effective in treating A. caninum infections.

In some cases, diethylcarbamazine, oxibendazole, moxidectin, and ivermectin may be prescribed to treat the infection.

It's essential to follow the veterinarian's instructions and complete the full course of medication to ensure the infection is fully cleared.

Detecting hookworm resistance is crucial to effective treatment. You can determine resistance by submitting feces to the AHDC parasitology laboratory for a pre-treatment quantitative Fecal Float (FLOAT), deworming the patient, and then submitting feces for a second quantitative fecal float 14 days after treatment.

This follow-up test code is FPCRT for a Fecal Parasite Count Reduction Test. The results of this test can be interpreted as follows: a fecal egg count reduction of >95% indicates an effective treatment, a reduction of 75-95% is essentially inconclusive, and a reduction of <75% indicates resistance to the dewormer used.

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Recent cases of drug-resistant hookworms have been detected at the Animal Health Diagnostic Center (AHDC).

Two greyhounds, a 3-year-old male and a 5-year-old female, showed signs of persistent hookworm infection despite previous treatment with fenbendazole.

The dogs were treated with a multi-drug dose for resistant hookworms, but the female dog's fecal egg count actually increased, indicating hookworm resistance to multiple dewormers.

A fecal egg count reduction test was performed 14 days after treatment, and the results were analyzed to determine the effectiveness of the treatment.

To determine hookworm resistance, you can submit feces to the AHDC parasitology laboratory for a pre-treatment quantitative Fecal Float (FLOAT), deworming the patient, and then submitting feces for a second quantitative fecal float 14 days after treatment.

Here's how to interpret the results:

If resistance to a single agent is detected, triple-combination drug therapy is recommended. If this therapy is less than 90% effective, it indicates a multi-drug resistant population of hookworms, and off-label administration of emodepside may be warranted.

In Canada, controlling anthelmintic-resistant isolates of hookworms requires a multi-faceted approach. The AHDC parasitology laboratory can help determine resistance by performing a quantitative Fecal Float (FLOAT) before and after treatment.

To effectively control anthelmintic-resistant hookworms, it's essential to use a triple-combination drug therapy if resistance to a single agent is detected. If this therapy is less than 90% effective, the population is considered multi-drug resistant, and off-label administration of emodepside may be warranted.

Monitoring fecal egg counts is crucial to determine the effectiveness of treatment. A fecal egg count reduction test can be performed 14 days after treatment, and the results can be interpreted as follows:

Intermittent positive fecal flotations can occur due to larval leakage, where hypobiotic larvae emerge from muscle tissues to repopulate the GI tract. This can make long-term management of hookworm resistance challenging.

Anthelmintic resistance is a growing concern in treating Ancylostoma caninum infections.

The use of ivermectin has been shown to be effective in treating Ancylostoma caninum infections, but resistance to this medication is on the rise.

Resistance to ivermectin is often caused by genetic mutations in the parasite, which can occur rapidly when the same medication is used repeatedly.

In areas where ivermectin resistance is common, alternative treatments such as albendazole may be more effective.

Albendazole has been shown to be effective in treating Ancylostoma caninum infections, especially in areas where ivermectin resistance is a problem.

However, albendazole may not be as effective in treating infections caused by other parasites, such as hookworms.

Regular monitoring of anthelmintic resistance is essential to ensure that the most effective treatment is used.

Frequent use of the same medication can contribute to the development of resistance.

It's essential to work with a veterinarian to determine the best treatment plan for your dog.

Ancylostoma caninum is a type of parasitic worm that affects dogs and humans. It belongs to the phylum Nematoda, which includes roundworms.

The classification of Ancylostoma caninum is as follows:

This parasitic worm is significant because it can cause a range of health issues in dogs, including heavy infections in young puppies and acute anemia.

Classification is a fundamental concept in biology that helps us understand the relationships between different living things. It's like organizing a library, where books are grouped together by author, title, and subject.

The classification of Ancylostoma caninum, a type of parasitic roundworm, is as follows: Kingdom Animalia, Phylum Nematoda, Class Secernentea, Order Strongylida, Family Ancylostomidae, and Genus Ancylostoma.

Here's a breakdown of the classification levels:

This classification system is based on the characteristics and features of the organism, such as its body structure, physiology, and behavior.

Ancylostoma caninum, the parasite responsible for hookworm infections in dogs, has significant implications for canine health. It causes heavy infections in sucking puppies and young dogs, leading to acute anemia, respiratory distress, and even death.

The effects of Ancylostoma caninum infections are not limited to puppies and young dogs. Lighter infections, often seen in older dogs, can induce chronic anemia, dullness, weight loss, or poor growth.

Interdigital dermatitis, also known as acrodermatitis, is another symptom associated with Ancylostoma caninum infections. This skin condition can be painful and uncomfortable for affected dogs.

Interestingly, Ancylostoma caninum can also be transmitted to humans, causing cutaneous larva migrans in tropical and subtropical areas. However, it's worth noting that Ancylostoma brasiliense is a more significant zoonosis in this respect.

A single worm can cause eosinophilic enteritis in humans, highlighting the potential risks of Ancylostoma caninum infections.