HEALTH

Fleas, , Lice, , and Flies By Lynn P. Schmeitzel and Peter J. Ihrke

Fleas are wingless, brown, fleas move rapidly on the skin bloodsucking insects that and are most easily found on may infest dogs and cats, and the rump and in the groin other warmblooded . area. Fleas transmit several dis- Sticktight fleas {Echidno- eases (for example, plague) phaga gallinácea) are found and parasites such as tape- on birds (especially chickens) worms. Young animals heav- and may attack dogs and cats ily infested with fleas may die exposed to infested birds. This from severe blood loss. Fleas flea attaches to the face of the prefer certain species of ani- animal and moves slowly. mals but will attack any The human flea (Pulex source of blood if the preferred irritans) may attack dogs and animal is not available. cats. The cat flea (Ctenocephal- Flea eggs laid on the host ides felis) and the dog flea are smooth and quickly fall off iCtenocephalides canis) both into the animal's environ- infest dogs and cats. C. felis is ment. The eggs are oval, the most common flea found white, and glistening. on dogs and cats. Cat and dog Small larvae hatch from the eggs and feed on the feces from adult fleas. After several molts, the last larval stage Lynn P. Schmeitzel is Assistant forms a pupal case. While in Professor of Dermatology, College the case, the larva develops of Veterinary Medicine, University of Tennessee, Knoxville. Peter J. into an adult flea. The adult Ihrke is Assistant Professor of flea emerges from the pupal Dermatology and Allergy, School case and searches for an of Veterinary Medicine, University animal. of California, Davis. Time required for the flea

464 Dogs and Cats ANIMAL HEALTH to develop from egg to adult have fleas. Therefore, all ani- may be as short as 16 days mals in the household must be during periods of warm tem- treated. All animals, the peratures and high humidity. house, and premises should be A small amount of flea sa- treated with appropriate in- liva is deposited in the skin secticides at frequent inter- each time the adult flea bites vals to prevent reinfestation. an animal. This saliva is very Contrary to recent folk- irritating and an allergic reac- lore, brewers yeast (a thia- tion can cause severe itching, mine or B^ source), garlic, or resulting in the skin disease sulfur are not effective in termed flea allergy dermatitis. either repelling or killing Biting and scratching fleas. around the rump and groin areas is the most common Ticks, Hard and Soft sign of flea allergy. Hair loss, Ticks are bloodsucking arthro- a red rash, and thickening of pod parasites of the skin. the skin are commonly seen. They transmit many diseases Fleas may be difficult to find such as Rocky Mountain Spot- in allergic animals since very ted Fever to people and ani- few flea bites are needed to mals. Severe blood loss may cause an allergic reaction. In result from heavy infestation. areas of the United States paralysis is a rare dis- where fleas are common, flea ease caused by a toxic sub- allergy dermatitis is the most stance in the saliva of some common itchy disease of the ticks. Recovery is rapid if the skin. ticks are removed. Flea feces (flea dirt) in Ticks have a four-staged the haircoat confirms the pres- life cycle including an egg, a ence of fleas. Flea dirt consists six-legged larva (seed tick), an of dehydrated blood from the eight-legged nymph, and an dog or cat and is reddish-black eight-legged adult. Ticks are and comma-shaped. identified as one-host, two- Successful treatment of host, and three-host ticks flea allergy dermatitis re- depending on the number of quires the absolute elimina- hosts required to complete tion of fleas from contact with their life cycle. the affected dog or cat. If one Hard ticks () and dog or cat in a household has soft ticks () are the fleas, it may be assumed that two main families of parasitic all animals in the household ticks.

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Hard ticks have a hard dog but also can parasitize shield on their backs distin- humans, wild animals, cattle, guishing them from soft ticks and horses. Adult American which do not. Most hard ticks Dog Ticks have white mark- require three different hosts ings on the shield on their to complete their life cycle backs. Outdoor areas such as and each stage only feeds fields are the major sources of once. American Dog Ticks. Thirteen species of eco- Removal. Hard ticks usu- nomically important ticks are ally are found securely at- in the hard tick (Ixodidae) tached by their head to the family. Most of these ticks are skin. Before removal, these acquired outside except for the ticks should be sprayed with Brown Dog Tick {Rhipice- an insecticide safe for use on phalus sanguineus) which can animals, or soaked with alco- infest buildings. hol. The head should be The Brown Dog Tick is grasped with an instrument widely distributed in North such as tweezers and pulled America. Since this tick sur- on gently until removed. Ciga- vives indoors, it can infest rettes, lighters, gasoline and kennels and households. The kerosene can severely injure Brown Dog Tick is a three- the skin and should never be host tick but all three stages used to remove ticks. If the can parasitize the dog. This ticks are Brown Dog Ticks, tick also parasitizes cats, the kennels and household horses, rabbits, and humans. premises may need repeated The Brown Dog Tick has no treatment with pesticides. white markings on the shield Soft ticks (Argasidae) on its back. have a leathery outer cover- The American Dog Tick ing. The Spinose Ear Tick {Dermacentor variabilis) is (Otobius megnini) is the only widely distributed in North medically important soft tick. America but is most common This tick is most common in on the Atlantic coast. These the southwestern parts of the ticks, unlike the Brown Dog United States. The young Tick, live only in grasses and stages (larvae and nymphs) shrubs. live in the outer ear canal of The larval and nymphal dogs, cats, cattle, and horses. stages of the American Dog Adult soft ticks do not feed Tick parasitize field mice. The and do not live on animals. adult tick usually infests the The Spinose Ear Tick can

466 Dogs and Cats I ANIMAL HEALTH cause severe irritation to the mouthparts for obtaining a ear canal and may occasion- blood meal, and have pincer- ally cause paralysis and sei- like claws for clinging to the zures in some animals. The hairs of their hosts. These lice animal should be taken to a are grey to red depending on veterinarian for removal of the amount of blood they have these ticks since the eardrum ingested. Sucking lice may may be damaged by improper cause severe anemia in heav- removal of the ticks, espe- ily infested young or debili- cially by sharp instruments. tated animals. Sucking lice can infest The Louse most domestic animals (except Lice are wingless insects that birds and cats). Infested ani- are uncommon parasites of mals are usually itchy and dogs and cats and are common often have rough dry coats. parasites of livestock and Sucking lice move slowly. birds in the United States. Biting lice usually are Lice spend their entire life yellow with a large rounded cycle on the host and are not head and mouthparts adapted readily transmitted from one for chewing and biting. Some animal species to another species have legs for clasping, (they are host specific). In others have legs for moving other words cat lice will not rapidly. These lice may cause usually infest dogs and vice severe hair loss from scratch- versa. Lice are spread from an ing and rubbing. Biting lice animal to another by direct can infest dogs, cats, cattle, contact. sheep, goats, horses, and Female lice attach their birds. eggs (nits) to the hairs or Specific identification of feathers on their hosts. The lice is difficult and is less im- young lice undergo several portant than being able to de- molts before becoming adults. termine if the louse is a biting Development from egg to species or the more harmful adult takes about 19 to 28 blood-sucking species. days. The dog has one common The two main types of lice biting louse (Trichodectes include sucking lice (Ano- canis) and one common suck- plura) and biting lice (Mallo- ing louse (Linognathus seto- phaga). sus). The cat has only one Sucking lice are larger common species, a biting louse than biting lice, have piercing (Felicola subrostratus).

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Adult lice and eggs at- onstrated by a veterinarian tached to hair and feathers performing a skin scraping, may be seen with the unaided removing the superficial layer eye. Lice and nits may be of a small area of skin with a found more readily by using a scalpel blade. The debris is magnifying hand lens with placed on a glass slide with good lighting. mineral oil and examined Many pesticides will kill with a microscope. adult lice but the eggs are Affects Dogs. Demodi- quite resistant. Consequently, cosis is a potentially serious animals should be treated and disease in the dog. If large then retreated two weeks numbers of Demodex canis later to kill the lice that have mites are found in several hatched from eggs not affected skin scrapings a diagnosis of by the first treatment. demodicosis may be made. There are two forms of All About Mites demodicosis in the dog—local- Demodectic mites {Demodex ized and generalized. Patchy spp.) parasitize many domestic hair loss on the head, forelegs, animals. These mites live in and trunk is called localized hair follicles in the skin. They demodicosis. In generalized crawl from the mother to the demodicosis hair loss, redden- nursing puppy or kitten dur- ing, and crusts may involve ing the first few days of life. the entire body. These ani- They do not cause any harm mals also may develop severe in small numbers and are con- bacterial infections in the skin. sidered normal inhabitants of An inherited defect in the the skin. These mites are not animal's immune system al- contagious from animal to an- lowing the mites to multiply imal, or animal to human. is believed to be an important The skin disease caused by an factor in development of gen- increased number of mites is eralized demodicosis. Since it called demodicosis or demo- is believed that the defect of dectic mange. the immune system is inher- Demodex spp. are elon- ited, dogs with demodicosis gated mites with short stubby should not be used for breed- legs. The life cycle includes an ing. Demodicosis is not a egg, a six-legged larva, an contagious disease. Affected eight-legged nymph, and an puppies were born with a pre- eight-legged adult. disposition to develop demodi- These mites can be dem- cosis.

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Diagnosis and treatment temic diseases such as diabe- of localized and generalized tes mellitus or feline leukemia demodicosis should be super- virus infection. Diagnosis and vised by a veterinarian. Local- treatment of feline demodi- ized demodicosis often does cosis should be supervised by not require any treatment and a veterinarian. usually will spontaneously cure in six to eight weeks. Oc- Sarcoptic Mites casionally the localized form The family Sarcoptidae in- will become generalized, so cludes the spp. and the affected areas and normal Notoedres spp. of mites. These skin must be closely observed. mites may affect many species No one can predict if a dog of animals but usually prefer with localized demodicosis will one species. They are spread spontaneously cure or develop by direct contact from one ani- generalized demodicosis. mal to another. A veterinarian usually This family of mites bur- will treat generalized demodi- row within the superficial lay- cosis with a series of parasiti- ers of the skin and the entire cidal rinses after clipping the life cycle is spent on the host hair. Antibiotics may be animal. The life cycle includes needed for a secondary bacte- an egg, a six-legged larva, two rial infection that is often eight-legged nymphal stages present. and an eight-legged adult. Rare in Cats. Demodicosis The development from egg to is a rare disease in cats. There adult takes about 17 days. are two types of demodectic The common skin disease mites in the cat: Demodex cati caused by sarcoptic mites is and an unnamed Demodex called scabies or sarcoptic spp. In localized demodicosis mange. The variety Sarcoptes there is patchy hair loss, red- scabei is named after a partic- dening, and occasionally ular host (for example, Sar- crusting on the neck, ears and coptes scabei var. canis—the head. In generalized demodi- sarcoptic of dogs). In all cosis hair loss, reddening, and animals, scabies is an in- crusting may involve the en- tensely itchy disease causing tire body. the animal to scratch, chew, Generalized demodicosis and rub constantly. may develop in cats secondary Canine scabies is a com- to suppression of the immune mon, contagious skin disease. system associated with sys- The most common signs are

Fleas, Ticks, Lice, Mites, Flies 469 ANIMAL HEALTH scaling, crusting, and a red United States yet may be rash on the head, ears, and common in certain local areas. abdomen. The entire body These mites are highly conta- may be affected. Many of the gious to other cats and occa- skin lesions are self-induced sionally may be transmitted since dogs with canine scabies to people and dogs. In the cat are almost constantly scratch- there is hair loss, thickening ing, chewing, and rubbing and crusting of the skin, usu- their skin. Severe itching is ally affecting the head and induced by very few mites and forelegs. These areas are se- may be due to an allergic re- verely itchy. action to the mites. Notoedres mites have Scabies is highly conta- morphologic characteristics gious from dog to dog. Dogs similar to Sarcoptes scabei obtained from sources with mites. These mites may cause large numbers of animals a red rash in humans. Usually housed together such as this rash spontaneously re- pounds, large puppy producing solves in people since No- establishments, and some pet toedres cati mites cannot com- shops are more likely to be af- plete their life cycle in human fected by scabies. skin, Scabies mites may be Parasiticidal rinses are transmitted to a human, re- used to treat . sulting in a red rash. Usually Since many parasiticides are the disease in humans is self- highly toxic to cats, a veteri- limiting since canine scabies narian always should super- mites apparently cannot com- vise the use of any parasiti- plete their life cycle in human cides in cats. skin. Ear Mites. The Psoroptic Since these mites often family of mites usually are are difficult to find by multi- parasites of cattle and sheep. ple skin scrapings, response to The life cycle includes an egg, treatment with parasiticidal a six-legged larva, two eight- rinses is often used by veteri- legged nymphal stages, and narians to diagnose canine an eight-legged adult. scabies. One member of this fam- Cat Scabies, Mange. ily, Otodectes cyanotis, the ear Feline scabies or notoedric mite, is a common cause of mange caused by Notoedres ear problems in the dog and catiis an uncommon skin cat. These mites generally are disease in many parts of the found in the outer ear canal

470 Dogs and Cats ANIMAL HEALTH but may rarely be found on The North American other parts of the body. The Chigger (Trombicula alfred- mites are readily transmitted dugesi) is the most common between dogs and cats. chigger that affects animals Ear mites cause severe ir- and people. On animals they ritation and thick, dry, black cause an itchy, red rash on crusts in the ear canals. The the belly, face, feet, and legs. mites may be seen with a Chiggers are orange-red in magnifying instrument called color. They may be found in an otoscope. They are large, the ears of cats. white, and mobile. Eardrops The larval mites remain usually are prescribed by attached to the skin for only a veterinarians to treat this few hours, so the larvae often disease. are difficult to find on the ani- Walking Dandruff. Cheyle- mal. Since chiggers leave vol- tiella spp. or Walking Dan- untarily, the only treatment druff Mites are contagious that may be needed is some- mites that live on the surface thing to stop the itching. of the skin. These mites cause Chigger infested areas should severe scaling, usually on the be avoided during summer back. Some itching may be and fall months to prevent seen but this disease usually recurrence. is not as itchy as the other Flies. The larvae of Cuter- skin diseases caused by mites ebra spp. flies infest cats, in dogs and cats. The mites dogs, rabbits, squirrels, and commonly affect dogs, cats, small rodents in the summer. and rabbits. They may be seen Pets acquire the larvae by in- with a magnifying hand lens vestigating rodent burrows. or in skin scrapings. Consequently the neck is most Chiggers are larval commonly affected. stages of the Trombiculid The larva penetrates the mites. Only the larval stages skin and forms a cavity under are parasitic. The nymphs and the skin. A breathing pore adults are free living. Chig- communicates with the out- gers are seen most often in side. Cuterebra larvae should the late summer and early fall be removed surgically by a and are obtained by contact veterinarian. with heavy underbrush.

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