Small Ruminants and Camelids

Internal parasites are arguably the most important aspect of small ruminant production. The most important internal parasite is the Barber Pole Worm (Haemonchus contortus) and can be found in sheep, goats, alpacas, and llamas. The widespread anthelmintic (“dewormer”) resistance displayed by the Barber Pole Worm should be a forewarning to equine producers as to how big of a problem they might be soon facing. A modified McMaster Fecal Egg Counting protocol can be applied to small ruminants and camelids in order to assess the internal parasite burdens of these animals.

THE EGGZAMIN™ SMALL RUMINANT AND CAMELID KIT

We have designed a Modified McMaster Fecal Egg Counting kit for small ruminants and camelids that provides you with everything you will need in order to accurately assess the internal parasite burdens of your animals. This customized testing kit will allow you to determine the type of parasite eggs and level of infection in the absence of costly shipping and laboratory fees that are typically associated with acquiring fecal egg count results. This tailored kit will allow you to:

Quickly administer a dewormer to individual animals based on a treatment threshold (which will reduce/slow the progression of anthelmintic resistance on your operation)
Test the effectiveness of your chosen dewormer that can potentially save lives of animals in dire situations (by conducting a Fecal Egg Count Reduction Test)
Make important culling and breeding decisions based on parasite tolerance (based on the 80:20 Rule).

Working in conjunction with the American Consortium for Small Ruminant Parasite Control (ASCRPC) to bring fecal testing to small ruminant owners and breeders, we gratefully link to their site for the latest in: Managing Internal Parasites in Sheep, Goats and Camelids.

MANAGING INTERNAL PARASITES IN SHEEP, GOATS, AND CAMELIDS.

Fecal Egg Counts: A Valuable Diagnostic Tool

Fecal Egg Counts (FEC) are an efficient diagnostic tool that can be used for many things. First and foremost, FEC will allow you to diagnose and determine the level of parasitisms that are infecting your flock or herd. In order to effectively and functionally administer parasite control methods, whether it be a dewormer, culling, or some other management strategy, you first must understand what is going on inside of your animals. FEC give you a bird’s eye view of their parasitisms and allow you to closely monitor the situation as the grazing season progresses.

Fecal Egg Count Reduction Tests

Fecal Egg Count Reduction Tests (FECRT) play a pivotal role in determining the effectiveness of anthelmintic treatments. By assessing the FEC fecal egg before a single dewormer is administered and again two weeks later from the SAME animal(s), then applying the counts to a simple equation (see below), you will be able to determine almost immediately the level of anthelmintic resistance on your operation. It is essential that you only use a single dewormer at a time when conducting a FECRT; this is so that you will be able to determine exactly which dewormers are working, and more importantly, not working. This information allows for informed decisions regarding treatment protocols, reducing/slowing the development of drug resistance.

Culling and the 80:20 Rule

A natural phenomenon that occurs in any given livestock group, such as your operation, is the 80:20 Rule. Here about 80% of the parasites are found in about 20% of the animals. This is true for any closed population of animals that has been allowed to come to an equilibrium with their parasites. (It should be noted that if you bring new animals on to your operation frequently, this rule does not apply.) Through FEC, a producer can determine the 20% of animals that are responsible for the 80% of parasitisms that are occurring on their place, cull these 20%, and they will have taken care of the majority of their worm problem.

Once you have identified the animals that harbor the highest parasitisms and removed them from your operation, the 80:20 distribution will still be in effect, however the intensity of the parasitisms will be reduced, making the parasite situation easier to manage. Following the FEC regularly will allow you to determine if any more animals need to be culled from your herd or flock.

Timely Detection and Targeted Treatment

Conducting FEC enables producers to identify animals that require treatments; typically treatments are only considered if the FEC is 1000 epg or higher, and then only if the animals is displaying other signs of parasitisms. This is called a “Treatment Checklist” (high FEC, pale eyelids <FAMACHA Score>, poor body condition, poor production status <poor milk production, poor weight gain, small babies that are not growing, etc.>) and should be applied each and every time a deworming treatment is considered. This information facilitates targeted treatments, ensuring that individuals that are heavily parasitized receive the necessary attention while minimizing unnecessary deworming treatments. By treating only the animals that require it, farmers can optimize their parasite management strategy, slow anthelmintic resistance on their operation, and reduce treatment costs.

Monitoring Parasite Population Dynamics

Regularly performing FEC and FECRT over time in a set population of animals helps in monitoring the population dynamics of internal parasites. By tracking the efficacy of anthelmintic treatments, farmers can identify any signs of reduced drug efficacy or emerging resistance in the parasite population in a very short amount of time. This knowledge allows for proactive adjustments to treatment protocols, preventing potential future outbreaks and minimizing the spread of drug-resistant parasites.

“Conducting FECRT in small ruminants and camelids is crucial for effective parasite management and should be conducted every time a dewormer is given.”

Comprehensive Parasite Management Strategy

Incorporating FEC tests into an overall your parasite control management plan enhances its effectiveness. Developing a Treatment Checklist used for determining deworming applications and combining other preventive measures such as pasture rotation, grazing management, and co-species/alternate species grazing, farmers can develop a comprehensive strategy to combat better manage internal parasites. FEC serve as an essential diagnostic tool within this integrated approach, enabling farmers to make data-driven, informed decisions for the health and long-term productivity of their small ruminants and camelids.

Conducting FECRT in small ruminants and camelids is crucial for effective parasite management and should be conducted every time a dewormer is given. By regularly assessing the efficacy of anthelmintic treatments, targeted and timely interventions can be implemented, ensuring optimal health and productivity. Monitoring parasite populations and making informed decisions based on the test results contribute to the reduction/slowing of drug resistance and the overall well-being of your animals. As responsible farmers, embracing FEC and FECRT as part of a comprehensive parasite management strategy is key to safeguarding the welfare of our small ruminants and camelids, and maximizing their productivity.

Parasites in Small Ruminants and Camelids

—Haemonchus contortus (Barber Pole Worm)

Small ruminants are highly susceptible to internal parasites, primarily gastrointestinal nematodes (worms). The most important of these gastrointestinal parasites is the Barber Pole Worm (Haemonchus contortus) and has become a major problem on a worldwide scale. These parasites are found in the abomasum (“true stomach”) and can cause significant damage and blood loss in your animals, leading to subsequent production losses: poor growth, reduced feed efficiency, anemia, poor milk production, iron and other mineral deficiencies, and even often times death. These issues are intensified if parasite burdens are left unchecked or if dewormers are used in absence of diagnostics (i.e. by using fecal egg counts). Recognizing the prevalence and impact of these parasites is the first step in effective parasite management. This parasite is a hot weather parasite and undergoes a seasonal arrestment (i.e., “hibernation”) during the cold winter months; it invades the abomasum wall and waits until conditions outside the animal are conducive for survival. The Barber Pole Worm produces about 5000 eggs per female worm in a single day, making pasture contamination and reinfection rates very high, especially in situations where animals are not grazed on a large amount of land and/or are confined to small paddocks or lots. In order to create an effective parasite management program in your operation, regardless of how many animals you have, it is vital that you recognize the prevalence of these parasites and impact that they have on your animals.

The Barber Pole Worm is a member of a group of gastrointestinal nematode parasites whose eggs are morphologically indistinguishable (i.e. they look the same and cannot be differentiated) called “Strongyles”. Strongyle parasites are found in all grazing livestock and different parasite species are important depending on the host animal. In small ruminants and camelids, the Barber Pole Worm is the most economically important strongyle parasite, and likely the only parasite that is causing both animal and monetary losses.

However, there are other strongyle parasites that can be commonly found in small ruminants and camelids. These include:

—Trichostrongylus colubriformis (Bankrupt Worm)

The Bankrupt Worm is a nematode that is found in most small ruminants and camelids and rides the coattails of the Barber Pole Worm, so to speak. Though the name elicits an image of a pathogenic worm, the Bankrupt Worm does not take a lot from the host animal and does not produce very many eggs per day (>100/day/female worm). This worm is typically susceptible to most dewormer classes, though it is not recommended to use dewormer to control this worm.

—Oesophagostomum venulosum/columbianum (Nodular Worm)

The Nodular Worm is found in the intestinal lining of the end of the small intestine and beginning of the large intestine of ruminants. It invades the intestinal lining as a natural part of the life cycle and can cause significant pathology in animals when found in high numbers. The parasite is typically found in low numbers on roughly 30-50% of operations and generally does not cause a problem. However, due to penetrating the skin as an infection route, if your operation has consistently wet conditions (i.e., heavy and constant rain, dairy operations, etc.), this worm might become an issue. The success of this parasite generally requires a “chronic carrier” host; this is a host animal that will always harbor a heavy infection and persistently seed the pastures with Oesophagostomum eggs.

—Teladorsagia circumcincta (Brown Stomach Worm)

The Brown Stomach Worm of small ruminants is a parasite that is found in the abomasum and is present in the more temperate regions of the world. This parasite can cause issues as it is in the same organ where the Barber Pole Worm resides (where there is geographical overlap), so a concurrent infection with both species could potentially create a more immediate problem. This parasite eats blood and can cause anemia, lesions, poor weight gains, poor milk production, and a poorly functioning organ. It also undergoes a seasonal arrestment (like the Barber Pole Worm), but the seasons are different depending on the geographic region and the intensity of the winter/summer. In the Northern US, the arrestment occurs in the winter and its larvae cycle on pasture during the warmer months. In the Southern US, arrestment occurs during the hotter months of the year and its larvae and persist on pastures during the winter. In the Western US, arrestment season is mixed between the winter and summer. The Brown Stomach Worm has also displayed resistance to Benzimidazoles and Avermectins.

—Chabertia ovina (Large Bowel-Mouthed Worm)

The Large Bowel-Mouthed Worm is a parasite that is found in the more temperate regions of the world, though is typically considered to be of lesser concern when compared to the Barber Pole Worm. It can contribute to economic losses when found in large numbers, such as reduced growth weights. Chabertia displays a seasonal arrestment during the cold winter months where it invades the large intestine lining and has displayed resistance to Benzimidazoles.

—Cooperia curticei (Sheep Cooperiad)

Cooperia curticei can be found in small ruminants but is rather rare in the US and is not typically found in fecal samples. When it is present, the pathology is mild and typically does not cause health problems.

Other Internal Parasites

Other internal parasites that infect small ruminants and camelids that can be important in certain situations (i.e. found in high numbers, immunocompromised animals, etc.) are:

—Eimeria spp. (Coccidiosis)

Coccidiosis is a protozoon parasite that is found in the small intestines and typically causes significant pathology in young and immunocompromised animals. Small to moderate amounts of cocci oocysts can be found in nearly all fecal samples but should only be treated if the infections are extremely high. Generally, coccidiosis is only a problem in birthing or winter barns where young animals are housed on soiled bedding. Coccidiosis is a ‘self-limiting’ disease, meaning if you remove an infected animal from the contaminated environment and get them on a good plane of nutrition, they will clear the infection without treatment in about 7-10 days. If the animal needs to be treated, amprolium or a sulfa drug is sufficient. There are cocci preventatives that can be added to the feed, as well.

—Nematodirus spp. (Intestinal Thread-necked Worm)

The Intestinal Thread-necked Worm is a large worm that is found in the small intestines of ruminants and is found in roughly 10-30% of operations. This parasite can cause significant pathology due to it strangling the intestinal villi, which are very important to the digestion process, as a means to stay in place. This action, called Thigmokinesis, causes the host to reject the villus from the intestinal lining and can cause significant damage. This can lead to weight loss/skinny animals and profuse diarrhea/dehydration. There is no treatment threshold for Nematodirus; if a single egg is seen during a fecal egg count, a Benzimidazole dewormer should be administered. It should be noted that the Benzimidazole dewormer will have no action against an infection of Barber Pole Worms.

—Trichuris spp. (Ruminant Whipworm)

The Ruminant Whipworm is an internal parasite that is found in the large intestine of ruminants and eats blood. This worm threads 2/3 of its body into the intestinal lining and is very anchored in place, making it difficult to kill with dewormers. The female parasites do not release eggs at a steady interval, instead coordinating the population’s egg output every few days. This coordinated egg dumping makes it difficult to accurately detect if only a single fecal egg count is performed; an egg count must be performed every day for 3-5 days in order to confirm infections. It is typically found in low numbers on roughly 10-25% of operations and generally does not cause significant pathology. The Ruminant Whipworm is typically disregarded and tolerated due to the general failure of dewormers and difficulty to detect via fecal egg counts.

—Strongyloides papillosus (Intestinal Threadworm)

The Intestinal Threadworm is found in the small intestine of ruminants and can be found on the majority of operations and typically does not cause significant pathology. Due to the complexity of its life cycle, its nearly permanent presence in the environment, and the fact that there is no good treatment for it, this parasite is generally disregarded and tolerated.

—Moniezia expansa (Sheep Tapeworm)

The sheep tapeworm is found in the small intestines of small ruminants and is of very little concern. Deworming treatments for tapeworms in ruminants are generally not advised as they do not cause significant pathology and, as such, treatments generally are not required.

—Parelaphostrongylus tenuis (Meningeal/Deer/Brain Worm)

The Meningeal/Deer/Brain Worm is a nematode that is found on the brain of gastropods (except cattle) and can cause significant neurological issues. The natural definitive host is the white-tailed deer; all other hosts are accidental/incidental and experience a plethora of neurological pathology. There are no good treatments for this nematode; anti-inflammatories and steroids are advised in order to reduce swelling of the brain. The infected animals either clear the infection or they don’t, and there is little in-between. This parasite cannot be detected in a fecal egg count and is diagnosed based on necropsy.