Sarcoptic Mange (Scabies):
Sarcoptes scabiei var bovis is a highly contagious disease spread by direct contact between infested and naive animals or by contaminated fomites. Lesions caused by this burrowing mite start on the head, neck, and shoulders and can spread to other parts of the body. The whole body may be involved in 6 wk. Pruritus is intense, and papules develop into crusts; the skin thickens and forms large folds. Diagnosis is made by deep skin scrapings, skin biopsy, or response to therapy. S scabiei var bovis can be transmitted to people and result in a transient, self-limiting dermatitis.
The following compounds are approved for use against sarcoptic mange mites in cattle at the labeled injectable and pour-on dosages: doramectin, eprinomectin, and ivermectin. Hot lime sulfur dips or sprays may be used, following the label instructions for species-specific dilution, with treatment repeated at 12-day intervals as needed, usually for a maximum of three treatments. Phosmet is also labeled for use against sarcoptic mange mites in cattle; two treatments may be required. Label instructions for dilution (multiple dilutions are listed) should be followed as appropriate. Certain spray formulations of permethrin are labeled for use against sarcoptic mange mites, but it is generally not considered the compound of choice. If permethrin is used, the animals should be wet thoroughly with the product and re-treated in 10−14 days.
Practitioners and producers should take care to note whether the compound, dose, and formulation are appropriate for the age of the animal and the production system in use. Eprinomectin and moxidectin pour-on formulations, as well as hot lime sulfur, are approved for use on dairy animals in the USA.
Psoroptic mange in cattle is caused by infestation with Psoroptes ovis. Current taxonomic and systematic classification of Psoroptes spp indicates that P ovis and P cuniculi (ear canker in rabbits, ear mange in sheep and goats) are strains or variants of the same species, with P ovis being found primarily on the backs and flanks of infested animals and P cuniculi in the ears. P ovis is not zoonotic.
P ovis is a nonburrowing mite that lives on the skin surface. All stages of the mite are found on the host, and transmission is through direct contact of infested and susceptible hosts. Transmission is also possible through contact with contaminated environments or fomites, because P ovis can survive off the host for ≥2 wk under the right conditions.
P ovis is a common parasite of cattle with a distribution limited to continental Europe and parts of the USA. It can be found in range and feedlot beef cattle from the central and western states, with the largest numbers of outbreaks historically reported from Texas, New Mexico, Oklahoma, Kansas, Colorado, and Nebraska. Clinical signs of P ovis infestation are rare in dairy cattle. These mites pierce host tissue and feed on serum and other fluid secretions from the bite wound. Exudates coagulate to form thick, scabby crusts. Alopecia is common with exudative dermatitis. Infestations are intensely pruritic, with papules, crusts, excoriation, and lichenification on the shoulders and rump initially, spreading to cover almost the entire body. Secondary bacterial infections are common in severe cases. Death in untreated calves, weight loss, decreased milk production, and increased susceptibility to other diseases can occur.
Treatment can be done by spray dipping or vat dipping; topical application of nonsystemic acaricides; and oral, topical, or injectable formulations of systemic drugs. Spray dipping is time consuming but useful for small herds, whereas vat dipping has fallen out of favor in the USA because of expense and the difficulty in managing proper concentrations of therapeutic compounds and proper cleanup. Toxaphene spray (0.5%–0.6%) was used historically; however, all uses of toxaphene were banned in the USA in 2001 and prohibited internationally through the Stockholm Convention on Persistent Organic Pollutants, effective 2004.
In the USA, the following treatments are labeled for use against P ovis in cattle at the labeled dosages: injectable doramectin, injectable ivermectin, and moxidectin (pour-on and injectable formulations). Hot lime sulfur dips or sprays may be used, following the species-specific dilution labeled on the package, with treatment repeated at 12-day intervals as needed, usually for a maximum of three treatments. Of these, only pour-on moxidectin and hot lime sulfur are approved for use on dairy animals. Certain spray formulations of permethrin are labeled for use against mange mites in cattle, but it is generally not considered the compound of choice. If permethrin is used, the animals should be thoroughly wet with the product and re-treated in 10−14 days. Outside the USA, other treatments are available and labeled for the control of mange, including flumethrin pour-on (2 mg/kg, repeated 10 days later), 0.3% coumaphos, 0.1% phoxim, 0.075% diazinon, and 0.025–0.05% amitraz. There are currently no amitraz products labeled for use on cattle in the USA. Diazinon is available for use on cattle only in an ear tag formulation in the USA; it is not labeled for treatment or prevention of mange. Products labeled for treatment and control of sarcoptic mange in cattle are considered effective against P ovis.
Chorioptic Mange (Leg Mange, Foot and Tail Mange, Symbiotic Mange, Barn Itch):
Chorioptic mange in cattle is caused by infestation with Chorioptes bovis or C texanus. Species of Chorioptes are not host specific, and C bovis can be found on domestic ruminants and horses throughout the world. Chorioptic mange caused by infestation with C bovis is the most common type of mange in cattle in the USA. C texanus has been reported on cattle from Brazil, China, Germany, Israel, Japan, Malaysia, South Korea, and USA. C bovis and C texanus are not zoonotic.
C bovis live on the skin surface and do not burrow. Life cycle stages include egg, larval, two nymphal, two female, and one male stage. Eggs are deposited on the skin, and secretions from female mites help secure eggs to the surface of their hosts. Eggs require 5–6 days to hatch, whereas each larval and nymphal stage requires 3–5 days for development. The entire life cycle may be completed in 21–26 days and depends on temperature and humidity. Transmission is by direct contact of infested and naive hosts. C bovis can live off their host for up to 3 wk and can be transmitted to cattle through contact with contaminated fomites and housing.
C bovis likely feeds on sloughed skin cells and other surface debris. While feeding, C bovis irritates the host skin, causing abrasions that become contaminated with secretions and feces from the mites. Most cattle are subclinically infested with C bovis. However, C bovis may cause an allergic, exudative, mildly pruritic, flaky dermatitis. Lesions include nodules, papules, crusts, and ulcers that typically begin at the pastern and spread up the legs to the udder, scrotum, tail, and perineum. Self-trauma and alopecia may be evident. Lesions and clinical signs appear in late winter and spontaneously regress during summer months. Chorioptic mange is less pathogenic than sarcoptic or psoroptic mange in cattle. Diagnosis is by observation of mites in skin scrapings.
In the USA, the following treatments are approved for use against C bovis at the labeled dosages: pour-on doramectin, eprinomectin (both pour-on and injectable formulations), and pour-on moxidectin. Hot lime sulfur dips or sprays are labeled for use against chorioptic mites and may be used following the label directions for species-specific dilution. Lime sulfur treatment should be repeated at 12-day intervals if needed. Of these, the pour-on formulations of eprinomectin and moxidectin as well as hot lime sulfur are approved for use on dairy animals in the USA.
Demodectic Mange (Follicular Mange, Bovine Demodicosis):
Three species of Demodex are known to infest cattle: D bovis, D ghanensis, and D tauri. D bovis is the most common and infests hair follicles of cattle worldwide. D ghanensis infests meibomian glands of cattle from Ghana, and D tauri has been recovered from hair follicles and sebaceous glands of cattle from Czechoslovakia. Species of Demodex are host specific and not zoonotic.
Demodex spp are unique among parasitic mites, because they are elongated with short, stumpy legs. Their distinct morphology is a presumed adaptation to living in hair follicles and sebaceous glands of their hosts. All life cycle stages are found on the host and include egg, larvae, two nymphs, and adults. These mites feed on sebum, protoplasm, and epidermal debris. Transmission of D bovis occurs through close contact of infested and naive hosts, with the transfer of mites from infested dams to neonates being the primary route.
Lesions consist of follicular papules and nodules, especially over the withers, neck, back, and flanks. Invasion by D bovis results in chronic inflammation, with formation of ulcers, abscesses, and fistulae due to follicular rupture or secondary staphylococcal infection. Pruritus is absent. Infestation of D bovis may result in considerable damage to hides. Cattle of any age are susceptible to demodectic mange, although disease is more evident in the young. Most cases are seen in dairy cattle in late winter or early spring. Infestation with D bovis is usually subclinical, and infestation may extend for many months. Diagnosis is by observation of mites in deep skin scrapings. Recovery is usually spontaneous; consequently, treatment is rarely performed. If therapy is instituted, the macrocyclic lactones listed for treatment of Sarcoptes scabiei var bovis or Chorioptes ovis should be considered.
Psorergatic Mange (Itch Mite):
Psorobia bos (formerly Psorergates bos) is a small mite that lives in the superficial layers of cattle skin. In most instances, P bos is nonpathogenic, and few cattle exhibit clinical signs of infestation. On rare occasions, mild pruritus, alopecia, and increased licking and rubbing have been attributed to infestation with P bos. This mite has been reported from cattle in the USA, Canada, the UK, and South Africa. P bos is not zoonotic. The disease does not cause significant economic losses; therefore, animals are usually not treated. The macrocyclic lactone products labeled for use for sarcoptic, chorioptic, and psoroptic mange likely control this infestation effectively.