The most important parasitic mite species on cattle are Psoroptes ovis that causes prosoptic mange, Sarcoptes scabiei var. bovis (also called scabies) that causes sarcoptic mange, and Chorioptes bovis that causes chorioptic mange. Another less frequent and rather benign cattle mange mite species is Demodex bovis, responsible for demodectic mange worldwide. All species occur worldwide and attack cattle of all ages and breeds.
Infestations with mites are technically called acariosis or acariasis, both on animals and humans.
Cattle mites are not vectors of other pathogens, i.e. they do not transmit microbial diseases as many other livestock parasites do.
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Biology and life cycle of cattle mites
In the past it was called Psoroptes bovis, because it was thought that Psoroptes mites that attack several domestic animals were individual species. Nowadays it is believed that they are only species-specific strains of Psoroptis ovis, the sheep mange mite. Adult Psoroptes mites are 0.75 mm long, i.e. they are usually only recognizable under the microscope. As for all mites, development goes through various larval and nymphal stages. A female mite lays 1 to 3 eggs a day, a total of about 50 to 100 eggs in her lifetime. Adult life lasts for about 50 days. The shortest life-cycle duration from eggs to eggs of the next generation is about 14 days.
Psoroptes mites do not dig tunnels in the skin. In the past it was thought that they pierce the skin of their hosts. Today it is believed that they do not pierce the skin, but that the mite feces cause an allergic reaction of the host's skin, which reacts producing exudations and skin thickening and hardening (lichenification) with formation of papules, scales and crusts (excoriations), often with hair loss. The mites than suck the exudates and secretions produced.
As all mite species, Psoroptes mites spend their whole life on the same host. Transmission within a herd is mostly by physical contact. The mites do not actively jump or crawl from one host to another one, but are passively transmitted when animals come in close contact. Nevertheless, Psoroptic mites and eggs can survive 2 to 3 weeks off the host by suitable conditions (maximum to 12 weeks by cold weather), i.e. animals can pick mites or eggs from their environment or can be transmitted by fomites. But there are no external vectors that transmit the mites, e.g. insects, worms, rats, mites, birds, etc., as it happens with many other parasites.
In regions with a cold winter (Canada, most of the USA and Europe, etc.) psoroptic mange is a typical winter pest, favored by livestock crowding due to indoor confinement during the cold season.
Psoroptic mange is a serious and harmful disease for cattle. Lesions often start at the tailhead, at the base of the horns or around the neck, and quickly spread to the rest of the body. Affected animals suffer from intense itching (pruritus) and react vigorously scratching, biting and rubbing against objects, which can cause injuries that can be infected with secondary bacteria. All this leads to weight loss, reduced milk production, and general weakness that makes the affected animals more susceptible to other diseases. Left untreated it can be deadly for severely affected calves. Hides of affected animals may be downgraded or rejected at slaughter.
Diagnosis has to be confirmed examining skin scrappings of affected parts under the microscope for visualization of the mites.
Psoroptic mites of cattle are not infectious for humans, dogs and cats.
Sarcoptes scabiei var. bovis
Sarcoptic mites of cattle are a species-specific strain of Sarcoptes scabiei, a mite species that infests also sheep, pigs, other livestock and also humans. This means that it can be transmitted to humans.
Sarcoptic mites are very small (0.3 to 0.5 mm) and can be seen only under the microscope. As all mite species, sarcoptic mange mites spend their whole life on the same host. The mites do not actively jump or crawl from one host to another one, but are passively transmitted when animals come in close physical contact. However, cattle can pick mites from the immediate environment or fomites. There are no external vectors that transmit the mites, e.g. insects, worms, birds, etc., as it happens with many other parasites.
The mites dig tunnels beneath the skin. Their saliva has potent digestive enzymes that dissolve the skin tissues. They feed on the resulting liquids. They do not suck blood. Adult females deposit their eggs in tunnels, which hatch in 3 to 5 days. The whole development through several larval and nymphal stages can be completed in less than 2 weeks. Adults live for 2 to 3 weeks. Off the host the mites survive only a few days.
Harm to cattle can be substantial. Mite digging causes skin irritation, which is enhanced by allergic reactions to the saliva that develop a few weeks after infestation. The affected skin develops pimples and papules that become crusty, with massive hair loss, progressive hardening and thickening, and building of large folds. Infestations start often on the head, the neck and the shoulders and may cover the whole body in about 7 weeks.
Affected animals suffer intense itching (pruritus) and react vigorously scratching, biting and rubbing the affected parts against whatever object. This caused injuries that can become infected with secondary bacteria. All this results in reduced weight gains, decreased milk production and general weakness that makes the affected animals more susceptible to other diseases. Outbreaks affect mostly groups or animals in close contact, seldom individual animals. It can be deadly for young cattle left untreated. Hides of affected animals may be downgraded or rejected at slaughter.
Sarcoptic mange is also a typical winter pest in regions wilt a cold winter. Outbreaks usually peak in late winter and early spring.
Diagnosis has to be confirmed examining skin scrappings under the microscope for visualization of the mites.
Chorioptic mites of cattle (also called "leg mites", or "barn itch") are less harmful than psoroptic or sarcoptic mites. They are not transmitted to humans.
They are also very small (0.4 to 0.6 mm) and can only be seen under the microscope. They have chewing mouthparts and neither suck blood, nor dig tunnels as sarcoptic mites, but bite the outer skin layers and feed on skin debris, fat, lymph or exudates. The whole development through several larval and nymphal stages can be completed in about 2 weeks. Off the host the mites survive only a few days.
Preferential sites or chorioptic mites are hoofs, lower part of the legs, and tail, from where it can spread to the udders and the between the hind legs. Affected parts show formation of scales and crusts.
Itching is not as severe as with psoroptic and sarcoptic mange, and the reactions of affected animals are also less vigorous. Secondary bacterial infections are seldom. As a consequence, economic impact on animal productivity (weight gain, milk production, etc.) is lower than for sarcoptic or psoroptic mange.
Chorioptic mange is also a typical winter pest in regions wilt a cold winter. Outbreaks usually peak in late winter and early spring. Once the animals leave the winter confinement, chorioptic mange mostly recedes spontaneously.
Cattle demodectic mange mites are even smaller (~0.25 mm) than psoroptic or sarcoptic mites. They get into the hair follicles and sebaceous glands and build nodules and papules that can become infected with secondary bacteria. The life cycle can be completed in about 2 weeks, but is poorly understood. Demodex mites can survive up to 4 months off the host.
Lesions of the host's skin consist of papules and nodules, especially over the neck, the back, and the flanks. It is more common in livestock kept under intensive conditions with close contact between animals. Demodectic mange can develop year-round, not only during the cold season.>
Unlike psoroptic and sarcoptic mites, demodectic mites do not cause itching and the affected animals are not severely affected. Therefore demodectic mange is usually rather benign and does not lead to significant economic losses due to weight loss or reduced milk production. However, the hides may be downgraded adt slaughter.
Prevention and control of cattle mites
As already mentioned, cattle mange is mostly a winter problem in regions with a cold season (e.g. Canada, most of the US and Europe, etc.). Crowding during indoor confinement means closer physical contact between the animals, which makes mite transmission easier. It also means a more humid hair coat, which is also favorable for mite development. Feeding is often deficient during the cols season, and confinement stresses the animals. These factors make the animals less resistant to the disease, especially to sarcoptic and prosoptic mange.
For all these reasons, keeping the animals well fed and in good health and hygienic conditions is crucial to reduce the risk of winter outbreaks, or at least to limit the harm that such outbreaks can cause.
As soon as the animals go back to pasture in spring symptoms recede quickly. Exposure to sun reduces the humidity in the hair coat, which slows down mite development, and without crowding mire transmission is significantly reduced.
For reasons yet unknown, a few mites often survive such unfavorable summer conditions in a few animals within a herd, without showing any clinical signs. Once the herd goes back to the winter quarters in fall, these animals will transmit the mites to the rest of the herd if preventive measures are not taken.
Therefore it is highly recommended to preventively treat the herds in late autumn. All animals in a herd must be treated, because it is impossible to know which are the carrier animals.
If a herd is free of mites, contamination can only com from cattle brought in. Consequently, to avoid contamination treat all incoming animals against mites, especially during the winter months. Two injections with a macrocyclic lactone (e.g. doramectin, ivermectin, moxidectin) with 7 to 10 days interval should do the job, but keep the animals isolated until 10 days after the second injection. Remember that cattle may be infected with mites without showing clinical signs! Topical products (sprays, dips, pour-ons, see below) can be used to treat incoming animals as well: they are cheaper, but les convenient and less reliable than injectables.
For the time being there are no vaccines that will protect cattle by making them immune to the mites. There are no repellents, natural or synthetic that will keep mites away from cattle.
There are no biological control means for controlling cattle mange mites (or any other mites of livestock and pets). Learn more about biological control of ticks and mites.
There are no traps for catching mites, for the simple reason that they spend their whole life on the animals.
To control established infestations it is crucial to treat all the animals in the herd, regardless of whether they show clinical symptoms or not.
A common practice in regions with a cold winter is to preventively treat all the animals in late fall when they leave the pastures for winter confinement indoors. Such treatments are also recommended to prevent lice infestations, which are also a winter pest in such regions. It is also important to treat with acaricides the premises, objects, and equipment that have been in contact with the sheep (e.g. boxes, pens, fencing, trailers, etc.) because mites or mite eggs may survive off the host for several weeks (depending on the species).
There are a number of products for dipping or spraying cattle against mites, whereby dipping is more likely to ensure coverage of all body parts that can carriy mites. Such products contain contact acaricides (i.e. non-systemic) effective against most mite and lice species: mainly organophosphates (e.g. chlorfenvinphos, chlorpyrifos, coumaphos, diazinon), amitraz or synthetic pyrethroids (e.g. deltamethrin, cypermethrin, flumethrin).
More convenient ready-to-use pour-ons are also available. They contain contact acaricides, mostly synthetic pyrethroids (e.g. deltamethrin, cypermethrin, flumethrin), or systemic macrocyclic lactones (e.g. doramectin, eprinomectin, ivermectin, moxidectin). Among the macrocyclic lactones only eprinomectin is approved for use on dairy cows. Non-systemic pour-ons may not provide complete protection because they not always ensure coverage of all body parts that can harbour mites (e.g. ears, udders, the legs), especially in the case of chorioptic mange.
Injectables for mite control contain always a macrocyclic lactone (e.g. doramectin, ivermectin, moxidectin). They are excellent against psoroptic and sarcoptic mange, but may not adequately control chorioptic mange.
Topical acaricides have a short residual effect, i.e. there efficacy does not last more than a week, if ever. And they often do not kill mites remaining deeply inside thick scabs and crusts. Therefore it is highly recommended to repeat the treatment once or twice with an interval of 2 to 3 weeks. This is also important because mites can survive off the hosts for several weeks and re-infest the herd, and because acaricides do not kill the eggs, which will hatch and re-start the infestation.
Drenches with macrocyclic lactones (e.g. with ivermectin) are mostly unsuited for mite control. The reason is that after oral administration the blood concentration achieved is lower than after injection, often insufficient to ensure mite control.
|If available follow national or regional recommendations or regulations for mite control.|
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Resistance of cattle mites to parasiticides
So far there are no reports on serious problems of cattle mites resistance to parasiticides.
This means that if a product fails to achieve the expected efficacy, it is extremely unlikely that it may be due to resistance of the mites to the product. Either the product was used incorrectly, or it was not appropriate for mange mite control.