Veterinary external parasites; life cycle, effect, treatment, and control

25/03/2023

Ticks
Tick basics

Ticks are commonly found in wooded areas, brush, shrubs and wild undergrowth, and any animal (or human, for that matter) that enters these environments is at risk of becoming a tick’s host. Immature ticks often feed on small, wild animals found in forests, prairies, and brush. Adult ticks seek larger hosts like dogs and cats which venture into these habitats. Tick exposure may be seasonal, depending on geographic location. There are many different species of ticks that can affect dogs and cats.

Ticks are capable of spreading serious infectious diseases.

Diagnosis, risks and consequences

Ticks are most often found around your dog’s neck, in the ears, in the folds between the legs and the body, and between the toes, but they can be found anywhere on the body and are usually easily seen or felt. Cats may have ticks on their neck or face. Tick bites can cause skin irritation and heavy infestations can cause anemia in pets. An adult female tick can ingest up to 100 times her weight in blood! Ticks are capable of spreading serious infectious diseases (such as Lyme disease, Rocky Mountain Spotted Fever, and others) to the pets and the people on which they feed. They can also cause tick paralysis. Disease risk varies by geographic area and tick species.

Treatment and control

Prompt removal of ticks is very important because it lessens the chance of disease transmission from the tick to your pet. Remove ticks by carefully using tweezers to firmly grip the tick as close to the pet’s skin as possible and gently and steadily pulling the tick free without twisting it or crushing the tick during removal. Crushing, twisting or jerking the tick out of the skin while its head is still buried could result in leaving the tick’s mouth parts in your pet’s skin; this can cause a reaction and may become infected. After removing the tick, crush it while avoiding contact with tick fluids that can carry disease. Do not attempt to smother the tick with alcohol or petroleum jelly, or apply a hot match to it, as this may cause the tick to regurgitate saliva into the wound and increase the risk of disease if the tick is infected.

Pets at risk for ticks should be treated during the tick season with an appropriate preventive. Your veterinarian can recommend a product best suited to your pet’s needs. Owners who take their pets to tick-prone areas during camping, sporting, or hiking trips should examine their pets for ticks immediately upon returning home and remove them from their pets. If your pet picks up ticks in your backyard, trimming bushes and removing brush may reduce your pet’s exposure and risk of infestation. And, if you find ticks on your pet, don’t forget to check yourself for ticks, too!

25/03/2023

Fleas
dog scratching
Fleas thrive when the weather is warm and humid. Depending on your climate, fleas may be a seasonal or year-round problem. Your pet can pick up fleas wherever an infestation exists, often in areas frequented by other cats and dogs. Adult fleas are dark brown, no bigger than a sesame seed, and able to move rapidly over your pet’s skin.

Once the flea becomes an adult, it spends virtually all of its time on your pet. Female fleas begin laying eggs within 24 hours of selecting your pet as a host, producing up to 50 eggs each day. These eggs fall from your pet onto the floor or furniture, including your pet’s bed, or onto any other indoor or outdoor area where your pet happens to go. Tiny, worm-like larvae hatch from the eggs and burrow into carpets, under furniture, or into soil before spinning a cocoon. The cocooned flea pupae can lie dormant (inactive) for weeks before emerging as adults that are ready to infest (or re-infest) your pet. The result is a flea life cycle of anywhere from 12 days to 6 months, depending on environmental factors such as temperature and humidity.

Diagnosis, risks and consequences

You may not know that your pet has fleas until their number increases to the point that your pet is obviously uncomfortable. Signs of flea problems range from mild redness to severe scratching that can lead to open sores and skin infections (“hot spots”). One of the first things you may notice on a pet with fleas is “flea dirt”—the black flea droppings left on your pet’s coat. You may not actually see the fleas themselves, but they can still be on your pet and in the environment.

Fleas bite animals and suck their blood; young or small pets with heavy flea infestations may become anemic. Some pets can develop an allergy to flea saliva that may result in more severe irritation and scratching; these pets can become severely itchy from just one or two flea bites. Also, pets can become infected with certain types of tapeworms if they ingest fleas carrying tapeworm eggs (a pet using its teeth to scratch the flea bites often eats the fleas). In areas with moderate to severe flea infestations, people may also be bitten by fleas. While fleas are capable of transmitting several infectious diseases to pets and people, this is rare.

Treatment and control

Your veterinarian will recommend an appropriate flea control plan for your pet based on your needs, your pet’s needs and the severity of the flea infestation.

Pets at risk for fleas should be treated during the flea season with an appropriate preventive. Your veterinarian can recommend a product most suitable for your pet.

Your veterinarian will recommend an appropriate flea control plan for your pet based on your needs, your pet’s needs and the severity of the flea infestation.

Because much of the flea’s life cycle is spent off of your pet, treating only your pet will not eliminate the problem. If you kill the adult fleas and do not kill the eggs, larvae and pupae, your pet will become re-infested when these fleas become adults and the cycle will start all over again. Therefore, in addition to treating your pet, reduce the flea population in your house by thoroughly cleaning your pet’s sleeping quarters and vacuuming floors and furniture that your pet comes in contact with frequently. Careful and regular vacuuming/cleaning of the pet’s living area helps to remove and kill flea eggs, larvae, and pupae.

You may be advised to treat your house with insecticides to kill the fleas; consult with your veterinarian about products safe for use around pets and children. Flea larvae are more resistant than adult fleas to insecticides. With moderate and severe flea infestations, you may also be advised to treat your yard. Your veterinarian can recommend an appropriate course of action and suggest ways

25/03/2023

04/02/2023

02/10/2022

Dairy cattle
As in beef cattle, the overarching theme for the prevention strategy of parasitic infection is to reduce the animals’ exposure to parasites and their infectious forms. Because multiple animals will be exposed, any strategy will focus on entire groups of animals rather than individuals. So far, this is similar to prevention strategies for any other infectious diseases on farm. However, when thinking about the prevention of parasite infections on farm, the veterinarian must be aware of the infectious form of the parasite (for example, eggs versus larvae) and whether or not other hosts are involved in the life cycle. Then the best parasiticide is selected and management practices, such as grazing schedule, are properly timed to avoid exposure to infectious parasite forms in the environment. In most cases, prevention strategies therefore boil down to good on-farm hygiene and use of well-timed and correctly selected dewormers, as well as pasture management as described for beef cattle. There are different forms of deworming medications for dairy cattle. For simplicity of application, many are pour-ons or feed additives; some are injectables. Oral pastes or any formulation that requires you to handle the animals’ heads is rarely used because it is labor-intensive. Any product used in an animal that may be used for milk or meat has a specific withdrawal time. Withdrawal time is defined as the period from when the drug was used until the milk may be put in the bulk tank or the animal sent to slaughter for meat. How long the withdrawal time is and whether you can use a given drug in a lactating cow depends on the product. One thing that people might not be aware of – once a cow has calved for the first time, she is always considered to be a lactating animal, even if she’s not being milked (dry period). Always, always, read the label to know what the product will treat for, at what dosage and frequency it should be used, by what route it should be administered, what class of animals it is for, and withdrawal times.

02/10/2022

Insecticide sprays and pour-ons are effective for many different external parasites but have the drawback of increased animal handling costs and stress during the fly-season. Insecticide sprays are the only way to manage adult stable flies. Ear tags impregnated with insecticide can be effective in fly control. Maximizing control requires two tags per animal, and timing of application with peak fly numbers often requires a separate handling session of the animals. Ear tags provide good face fly control if applied properly.
Larvicides prevent fly larvae from developing in to adults and are administered through free choice mineral. To be effective cattle must consume an adequate amount and not be in the proximity of untreated cattle
Injectable products and pour-ons with systemic activity are mainly the macrocyclic lactones. These are effective against some flies as well as mites and lice. For mites and lice a second treatment may be needed in two to three weeks to kill newly hatched parasites unless using an extended duration product.
Sanitation or cleaning up of wasted feed or manure that serve as egg-laying sites for certain flies can greatly contribute to the control of certain flies locally. In addition, egg laying sites may be treated with a larvicide.
Environmental management may be a key component to tick control. The reduction of brushy areas and thick wooded areas reduces the habitat for the ticks and reduces exposure.
Certain native parasitic wasps are used as biological control agents of fly populations. Currently, farmers can buy parasitic wasps from commercial insectaries. These wasps emerge into adulthood from the pupal stage, where they develop wings. They fly from the release stations in which they have been held, hung from barn ceilings or other out-of-reach places. The wasps only target flies in their pupal stage. When the wasp finds a pupa in soil or litter, she inserts her stinger and withdraws it, drawing blood and paralyzing the pupa and inserting one egg. The egg hatches after 1 day, and the larva feeds on body fluids and organs for 2-4 weeks. Eventually, the wasp chews its way out of the dead host’s puparium and flies away as an adult.

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02/10/2022

Some pasture management activities may include leaving the pasture fallow, grazing other species, and dragging manure pats during the dry season to allow them to dry out.
Anthelmintics used to control internal parasites for beef cattle come in several forms including paste, injectable, drench, pour-on, bolus, and as a feed or mineral additive. Products have varying lengths of activity and costs, but fall into two main classes: benzimidazoles and macrocylic lactones. Benzimidazoles (white dewormers) available commercially contain albendazole, fenbendazole, or oxfendazole. Benzimidazoles are effective against most of the major adult gastrointestinal parasites and many of the larval stages. Products come in various oral formulations and have a short duration of efficacy. Macrocyclic lactones are the avermectins and milbemycins. Products in commercial use contain ivermectin, doramectin, eprinomectin, or moxidectin. The macrocyclic lactones have a potent, broad antiparasitic spectrum at low dose levels. They are active against many larval stages (including hypobiotic larvae) and are active against many external parasites as well. Products are available as oral, subcutaneous, and pour-on formulations for use in cattle. Duration of efficacy varies with the product and may be up to 35 days.
Approaches used to treat parasites in beef cattle are considered strategic deworming. This is the practice of treating cattle at times to not only get the benefit in that animal to prevent economic loss but also reduce environmental contamination for a period of time at least equal to the life cycle of the parasite removed.
Keys to strategic deworming are to place cattle that are not shedding eggs on pastures that are not infected; this is accomplished by deworming prior to spring turnout or fall treatment in the north (following killing frost). The benefit of treating in the fall is that cattle should be free of internal parasites all winter and going into the spring turnout (assuming an effective product was used). Cattle that go onto pasture at spring turnout are free of parasites, thus not shedding eggs, and will be consuming the infective larvae on the pasture if the pasture is contaminated. By consuming the infective larvae and not shedding new ones the cows will be reducing the load on the pasture (acting as vacuum cleaners). After a time the ingested infective larvae will mature and cows will start shedding eggs. Strategic deworming times the treatment so as to reduce the worm burden on the cattle and also decrease the parasite contamination of the pasture during the highest parasite period (spring/early summer).
The timing of these treatments can and should be timed with other management procedures such as summer vaccines for the calves and fall processing of calves and cows. Depending on the geographic location, such as in the south where the weather (moisture) is different, timings may be different, as well as the type of grazing program.
Calves and stockers should be considered within a strategic program while on a grazing program. Times of concern include prior to weaning while nursing the cow and while intensively grazing as a stocker. Calves should not be dewormed while being weaned. Preweaning treatment, prior to the stress of weaning, can reduce the potential negative impact on immune function as well as improve performance. Any time cattle are moving from pasture into a dry lot setting is a good time to deworm as this should clear cattle of parasite load for the time in the dry lot (similar to fall deworming) as there is no green grass to graze.
For the control of other types of internal parasites such as tapeworms (cestodes), flukes (trematodes), and protozoans (such as coccidia), similar concepts are applied. It is important to understand the different life cycles of these different types of parasites as well as the efficacy of products used to treat them.rin or an organophosphate. Strategies or combinations of strategies for delivery include: dust bags, back-rubbers (oilers), animal sprays, pour-ons, and insecticide impregnated ear tags. In addition, the use of injectable products or pour-ons with systemic activity work well to control lice and mites. Larvicides can also be part of control plan for certain types of flies as well as the use of predator wasps and environmental management. The use of dust bags and back-rubbers (oilers) can provide delivery of insecticides and economic fly control if located in an area that cattle are forced to move through such as a gateway or over a mineral feeder.

02/10/2022

Some pasture management activities may include leaving the pasture fallow, grazing other species, and dragging manure pats during the dry season to allow them to dry out.
Anthelmintics used to control internal parasites for beef cattle come in several forms including paste, injectable, drench, pour-on, bolus, and as a feed or mineral additive. Products have varying lengths of activity and costs, but fall into two main classes: benzimidazoles and macrocylic lactones. Benzimidazoles (white dewormers) available commercially contain albendazole, fenbendazole, or oxfendazole. Benzimidazoles are effective against most of the major adult gastrointestinal parasites and many of the larval stages. Products come in various oral formulations and have a short duration of efficacy. Macrocyclic lactones are the avermectins and milbemycins. Products in commercial use contain ivermectin, doramectin, eprinomectin, or moxidectin. The macrocyclic lactones have a potent, broad antiparasitic spectrum at low dose levels. They are active against many larval stages (including hypobiotic larvae) and are active against many external parasites as well. Products are available as oral, subcutaneous, and pour-on formulations for use in cattle. Duration of efficacy varies with the product and may be up to 35 days.
Approaches used to treat parasites in beef cattle are considered strategic deworming. This is the practice of treating cattle at times to not only get the benefit in that animal to prevent economic loss but also reduce environmental contamination for a period of time at least equal to the life cycle of the parasite removed.
Keys to strategic deworming are to place cattle that are not shedding eggs on pastures that are not infected; this is accomplished by deworming prior to spring turnout or fall treatment in the north (following killing frost). The benefit of treating in the fall is that cattle should be free of internal parasites all winter and going into the spring turnout (assuming an effective product was used). Cattle that go onto pasture at spring turnout are free of parasites, thus not shedding eggs, and will be consuming the infective larvae on the pasture if the pasture is contaminated. By consuming the infective larvae and not shedding new ones the cows will be reducing the load on the pasture (acting as vacuum cleaners). After a time the ingested infective larvae will mature and cows will start shedding eggs. Strategic deworming times the treatment so as to reduce the worm burden on the cattle and also decrease the parasite contamination of the pasture during the highest parasite period (spring/early summer).
The timing of these treatments can and should be timed with other management procedures such as summer vaccines for the calves and fall processing of calves and cows. Depending on the geographic location, such as in the south where the weather (moisture) is different, timings may be different, as well as the type of grazing program.
Calves and stockers should be considered within a strategic program while on a grazing program. Times of concern include prior to weaning while nursing the cow and while intensively grazing as a stocker. Calves should not be dewormed while being weaned. Preweaning treatment, prior to the stress of weaning, can reduce the potential negative impact on immune function as well as improve performance. Any time cattle are moving from pasture into a dry lot setting is a good time to deworm as this should clear cattle of parasite load for the time in the dry lot (similar to fall deworming) as there is no green grass to graze.
For the control of other types of internal parasites such as tapeworms (cestodes), flukes (trematodes), and protozoans (such as coccidia), similar concepts are applied. It is important to understand the different life cycles of these different types of parasites as well as the efficacy of products used to treat them.

02/10/2022

BEEF CATTLE
Parasites can have potential negative effects on beef cattle that can vary from subclinical immune suppression, irritation, annoyance, appetite suppression, and decreased production, to severe clinical disease and death. The management of parasites is a component of a preventive health program that should also include immunity management (vaccinations), management procedures, handling, and nutritional considerations that reflect an in-depth understanding of not only the beef production system but farm-specific issues and goals.
Internal Parasites
Internal parasites include roundworms (nematodes), tapeworms (cestodes), flukes (trematodes) and protozoans (such as coccidia). Roundworms are considered the most economically important, and many programs revolve around their management. This section regarding internal parasites in beef cattle will focus around roundworms. Understanding the parasite life cycle and the level of parasite pressure is key to the management of internal parasites.
The following is the basic life cycle of internal (gastrointestinal) parasites in cattle:
Adult parasites live in the gastrointestinal tract of cattle and lay eggs that are shed in the manure.
When a parasite egg is shed on the pasture in the f***s, this egg begins development, embryonating into a first stage larva (L1), then molting into a second stage larva (L2), and finally molting again into a third and infective stage larva (L3).
During the first two larval stages in the f***l pat, the larva are fairly immobile, feeding off the bacteria and other debris found in the f***s.
During the third larval stage the larva move out of the f***l pat and onto nearby grass where they are consumed by cattle.
L3 larvae maintain an external sheath covering that provides extra protection from environmental conditions allowing survival during winter or drought conditions. This sheath prevents feeding, thus L3 larvae have a limited life span.
Egg development is greatly dependent upon temperature and moisture. Eggs that are passed in the middle of winter will not develop until warm weather returns in the spring. Eggs passed in the middle of a drought or other unfavorable conditions may develop into infective larvae in the f***s but without moisture cannot move away from the pat where they can be consumed by a host animal when it eats grass. Eggs that are shed during favorable conditions can develop into infective larvae in just a few days if temperatures are warm and moisture is plentiful.
Once consumed by cattle, the infective larvae mature into adults over a period of 3-4 weeks (shorter in younger cattle, longer in adult cattle) and begin to lay eggs, which are shed onto pastures to start the cycle over again.
Some larvae can become inhibited or hypobiotic (go into hibernation) in the wall of the abomasum, sometimes referred to as L4 larvae. This process can occur during the winter in the north and in the summer in the south, with these larvae maturing and developing into adult worms when the environment for egg survival is more favorable.
Overall, the controlling of internal parasites has a significant positive return on investment for producers. The main focus of internal parasite control in beef cattle is roundworms. Diagnostics are needed to determine which specific worms are present. For beef cattle this is important because the roundworm life cycle depends on the shedding of the eggs on pasture, larvae development, and the ingestion of the larvae during grazing. Since much of beef cattle production depends on grazing of pastures, the management of roundworms is key. As long as cattle have access to grass, they will have an internal parasite challenge.
Control practices should consider the class (or age) of cattle, nutrition status, stress level, season, and likelihood of parasite contamination of the environment, and involve the use of pasture management options as well as the use of anthelmintic (dewormer) products for treatment.

02/10/2022

PARASITE INFECTION AND TOOLS FOR DIAGNOSIS
Parasites, either internal (for example, worms) or external (for example, fleas and ticks), draw nutrients away from the host, and can cause disease. This chapter will focus on demonstration of how your understanding of the life cycle of parasites for various species in different environments will help minimize infection or infestation and help with control of the parasite in the environment. The biggest difference appears to be in overall management between large animals and small animals. In large animals, there is concern about resistance of parasites to available deworming medications and great attention is paid to minimizing development of resistant parasites. This may include leaving a small population of worms untreated, so there always are susceptible worms in the overall population and we are not just continually killing off susceptible worms and leaving behind more and more resistant worms. In small animals, where parasites can be a significant public health concern, it is a goal to kill all internal and external parasites. This does not mean there are no concerns about resistance; in 2021, resistance in hookworms, one intestinal parasite of dogs
Gastrointestinal parasites are the class most commonly addressed. Some common tools used to evaluate presence of gastrointestinal parasites are f***l flotation tests and f***l egg counts. F***l egg counts are basically quantified f***l flotations. You will also hear f***l flotations called f***l floats. Dr. Erin Burton provides the following differentiation between these two kinds of tests and how they’re interpreted: A f***l flotation is a qualitative assessment of the eggs in a sample, while a f***l egg count (FEC) is a quantitative assessment. F***l flotations are lax on the amount of solution and f***s used for each float and so give at best a semi-quantitative assessment of egg burden. FECs use a measured amount of f***s and solution, and then plug the number into a formula to get the egg count. FEC usually is done more than once; in order to interpret them they are performed over time and because of that they are the test primarily used to definitively define the degree of drug resistance in an animal or herd. It is also important when evaluating a f***l float or FEC to be aware of how prolific of an egg layer the nematode is. For example, one Toxocara canis (roundworm) can produce over 20,000 eggs each day while a whipworm only produces about 1000 per day. Thus, having larger numbers of whipworm eggs on a float or FEC is more indicative of a heavy worm burden than abundant Toxocara eggs on float or FEC. Finally, be aware that not all gastrointestinal parasites can be identified by f***l flotation testing. For example, tapeworm eggs generally are released within tapeworm segments, or proglottids, and because the individual eggs are not in the f***s and the proglottids are too heavy to float, tapeworm infections generally cannot be diagnosed by f***l flotation testing.

02/10/2022

Demodectic mange mite basics
Demodectic mange caused by demodectic mange mites is mainly a problem in dogs. Demodectic mange mites are microscopic and not highly contagious. In general, demodex mites are not spread to other animals or across species. A mother dog, however, may pass the mites to her puppies.
Diagnosis, risks and consequences
Localized demodectic mange tends to appear in young dogs (usually less than 6 months old) as patches of scaly skin and redness around the eyes and mouth and, perhaps, the legs and trunk. Itching is not common with this type of mite infestation unless a secondary infection has occurred. Unlike other types of mange, demodectic mange may signal an underlying medical condition, and your pet’s overall health should be carefully evaluated. Less commonly, young and old dogs experience a more severe form of demodectic mange (generalized demodecosis) and can exhibit widespread patches of redness, hair loss, and scaly, thickened skin Dogs with demodecosis can develop secondary bacterial infections which require additional treatment.
Cats are rarely infected with demodex mites, and the cat demodex mite is not the same as the dog demodex mite. Affected cats develop hair loss, crusts and scaly skin around the face, neck and eyelids, and may excessively groom the areas. They may also be more itchy than dogs affected by demodex.
Demodectic mange is usually confirmed by taking a skin scraping and examining it under a microscope.
Treatment and control
Your veterinarian will discuss treatment options with you. Treatment of dogs with localized demodectic mange generally results in favorable outcomes. Generalized demodecosis is more difficult to treat, and aggressive, extended treatment may be necessary.

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02/10/2022

Ticks
Tick basics
Ticks are commonly found in wooded areas, brush, shrubs and wild undergrowth, and any animal (or human, for that matter) that enters these environments is at risk of becoming a tick’s host. Immature ticks often feed on small, wild animals found in forests, prairies, and brush. Adult ticks seek larger hosts like dogs and cats which venture into these habitats. Tick exposure may be seasonal, depending on geographic location. There are many different species of ticks that can affect dogs and cats.
Ticks are capable of spreading serious infectious diseases.
Diagnosis, risks and consequences
Ticks are most often found around your dog’s neck, in the ears, in the folds between the legs and the body, and between the toes, but they can be found anywhere on the body and are usually easily seen or felt. Cats may have ticks on their neck or face. Tick bites can cause skin irritation and heavy infestations can cause anemia in pets. An adult female tick can ingest up to 100 times her weight in blood! Ticks are capable of spreading serious infectious diseases (such as Lyme disease, Rocky Mountain Spotted Fever, and others) to the pets and the people on which they feed. They can also cause tick paralysis. Disease risk varies by geographic area and tick species.
Treatment and control
Prompt removal of ticks is very important because it lessens the chance of disease transmission from the tick to your pet. Remove ticks by carefully using tweezers to firmly grip the tick as close to the pet’s skin as possible and gently and steadily pulling the tick free without twisting it or crushing the tick during removal. Crushing, twisting or jerking the tick out of the skin while its head is still buried could result in leaving the tick’s mouth parts in your pet’s skin; this can cause a reaction and may become infected. After removing the tick, crush it while avoiding contact with tick fluids that can carry disease. Do not attempt to smother the tick with alcohol or petroleum jelly, or apply a hot match to it, as this may cause the tick to regurgitate saliva into the wound and increase the risk of disease if the tick is infected.
Pets at risk for ticks should be treated during the tick season with an appropriate preventive. Your veterinarian can recommend a product best suited to your pet’s needs. Owners who take their pets to tick-prone areas during camping, sporting, or hiking trips should examine their pets for ticks immediately upon returning home and remove them from their pets. If your pet picks up ticks in your backyard, trimming bushes and removing brush may reduce your pet’s exposure and risk of infestation. And, if you find ticks on your pet, don’t forget to check yourself for ticks, too!

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