Mange and Sarcoptic Mange in Animals

Mange

• Mange is a contagious condition marked by crusty or scaly skin, pruritus, and alopecia
• It is a term for cutaneous acariasis resulting from parasitic mite infestation
• Mites involved include Demodex, Sarcoptes, Otodectic, Cheyletiellosis, and Straelensiosis

Sarcoptic Mange (Canine Scabies)

• Etiology: Sarcoptes scabiei var canis
• Adult mites are 0.2-0.6 mm long, roughly circular with small triangular spines, and have 4 pairs of short legs
• Female mites are almost twice the size of males
• Their entire life cycle lasts 17-21 days on the dog, with females burrowing to lay eggs
• Clinical signs may appear 10 days to 8 weeks after contact with an infected animal
• It causes intense pruritus (itching) due to hypersensitivity to mite products

Scabies incognito

• Scabies incognito describes well-groomed dogs with sarcoptic mites
• These dogs are pruritic
• Demonstrating mites via skin scraping is difficult because crusts and scales are removed by bathing

Macroscopic Lesions

• Primary lesions are papulocrustous eruptions with thick, yellow crusts, excoriations, erythema, and alopecia
• Lesions start on the ventral abdomen, chest, ears, elbows, and hocks, and can generalize if untreated

Microscopic Lesions

• Dogs with chronic, generalized disease develop seborrhea and severe skin thickening with fold formation
• Other symptoms include crust buildup, peripheral lymphadenopathy, and emaciation

Transmission

• Mites are fairly host-specific, but can affect animals and people in contact with infected dogs
• Sarcoptic mange spreads readily between dogs through direct or indirect contact

Diagnosis of Sarcoptic Mange

• Based on history of severe pruritus with sudden onset, potential exposure
• Consider involvement of other animals or people
• Extensive superficial scrapings done in ears (non-excoriated), elbows, and hocks are needed
• Centrifugation fecal flotation using sugar solutions may reveal mites or eggs
• ELISA detects specific antibodies

Sarcoptic Mange Treatment

• Systemic scabies treatment involves macrocyclic lactones:
  • Selamectin: spot-on at 6mg/kg
  • Imidacloprid-moxidectin: spot-on for dogs 7+ weeks old, two doses of 2.5mg/kg, 4 weeks apart
• Endectocides:
  • Milbemycin oxime and Ivermectin: effective but not registered; dosage and route of administration dependent
  • Milbemycin oxime: 2mg/kg, PO, weekly for 3-4 weeks
  • Ivermectin: 200mcg/kg, PO or SC, 2-4 treatments 2 weeks apart

Otodectic Mange

• Otodectic mange etiology: Otodectes cynotis
• Mites from the family Psoroptidae are in the vertical and horizontal ear canals, sometimes on the body

Clinical Signs of Otodectic Mange

• Head shaking
• Constant ear scratching
• Ear drooping
• Pruritus, varying in severity

Macroscopic Lesions of Otodectic Mange

• Dark brown cerumen accumulation in the ear
• Suppurative otitis externa
• Perforation of the tympanic membrane in severe cases

Otodectic Mange Treatment

• Affected and in-contact animals should receive appropriate parasiticide treatment in the ears
• Topically apply selamectin and moxidectin
• Clean the ear with an appropriate ceruminolytic agent along with any therapy

Cheyletiellosis (Walking Dandruff)

• Etiology: Cheyletiella yasguri
• Highly contagious, especially in animal communities; frequent human infestation
• Mites have 4 pairs of legs, prominent hook-like mouthparts, live on the epidermis surface
• Entire life cycle lasts 3 weeks on the host

Clinical Signs of Cheyletiellosis

• Scaling
• Dorsal distribution
• Pruritus, varying from none to severe

Diagnosis of Cheyletiellosis

• Mites and eggs are hard to find, especially in bathed animals
• Acetate tape preparations, superficial skin scrapings, and flea combing aid diagnosis

Treatment of Cheyletiellosis

• Topical and systemic acaricides are effective, but no drugs are currently licensed
• Topical drugs: lime sulfur, fipronil spot-on/spray, permethrin, and amitraz
• Extra-label systemic drugs: oxime (PO) and ivermectin (SC)

Canine Demodicosis

• Etiology: Demodex canis
• Demodex canis inhabit hair follicles/sebaceous glands, small numbers are normal flora
• Overpopulation causes clinical disease
• Pathogenesis is complex, hereditary predisposition for generalized disease is strong

Forms of Demodicosis

• Localized demodectic mange: seen in dogs usually <1 year old
• Juvenile-onset generalized demodicosis: inherited immunologic defect with functional abnormality associated with the cell-mediated immune system
• Adult-onset generalized demodicosis: associated with/triggered by neoplastic process/debilitating disease with immunosuppression

Clinical Signs of Localized Demodectic Mange

• Lesions confined to lips, periorbital area, and forelimbs but may be elsewhere
• Juvenile-onset generalized demodicosis: severe disease, generalized erythema, papules, alopecia, and crusts
• Adult-onset generalized demodicosis: clinically similar to juvenile-onset, seen in adult dogs

Macroscopic Lesions of Localized Demodectic Mange

• One to five well-defined areas of alopecia, erythema, and scaling
• Pruritus usually absent or mild
• Juvenile-onset generalized demodicosis: oily seborrhea, edema, hyperpigmentation, secondary bacterial infections (pyodemodicosis)

Microscopic Lesions of Canine Demodicosis

• Systemic illness with generalized lymphadenopathy, lethargy, and fever when deep pyoderma, furunculosis, or cellulitis is seen

Transmission of Canine Demodicosis

• Mites are transmitted from dam to puppies during nursing within the first 72 hours of birth

Diagnosis of Canine Demodicosis

• Diagnosis is easy since deep skin scraping or hair plucking reveals mites, eggs, and larval forms in high numbers

Treatment of Canine Demodicosis

• Hair clipping and body cleansing with benzoyl peroxide shampoo (follicular flushing activity) is required
• Whole body amitraz dips (0.025%) every 2 weeks are the only approved demodecosis treatment
• Higher concentrations (0.05%) and shorter treatment (1 week) may be more efficient

Trombiculosis

• Etiology: Neotrombicula autumnalis and Eutrombicula alfreddugesi
• Seasonal, noncontagious acariasis caused by parasitic larval stage of Trombiculidae (Chiggers)
• Adults (harvest mites) and nymphs look like small spiders, live on rotting detritus
• Larvae (0.25mm) attach to host, feed, detach when engorged, become ovoid, 0.7mm, orange to red, immobile dots on head, ears, feet, or ventrum
• Pathogenicity is through traumatic and proteolytic activities

Clinical Signs of Trombiculosis

• Clinical signs include hair loss and crust
• Macroscopic lesions include erythema, papules, and excoriations
• Intense pruritus can persist for hours to days after the larvae has left the animal

Diagnosis of Trombiculosis

• Based on history and clinical signs
• Differential diagnosis includes other pruritic dermatoses
• Diagnosis confirmed by careful examination of affected areas
• Microscopic exam of skin scrapings identifies larvae, oval-shaped body, curved pedipalps with claws

Treatment of Trombiculosis

• Pyrethroids with repellent-like activity prevent infestation
• Fipronil and permethrin are used for prevention and treatment

Canine Distemper (Hard Pad Disease)

• Etiology: single-stranded RNA virus of the family Paramyxoviridae
• Closely related to the viruses of measles and rinderpest

Transmission of Canine Distemper

• Aerosol droplet secretions from infected animals

Clinical Signs of Canine Distemper

• Salivation and chewing movements of the jaw (“chewing-gum fits”)
• Localized involuntary muscle twitching (myoclonus, chorea, flexor spasm, hyperkinesia)
• Walking in circles, head tilting, nystagmus (uncontrolled, rapid eye movements)
• Focal to generalized seizures, paresis to paralysis

Prevention of Canine Distemper

• Vaccinate puppies with MLV vaccine at 6 weeks old, repeat every 3-4 weeks until 16 weeks old
• Administer MLV measles vaccine intramuscularly to pups 6-7 weeks old
• Follow with two+ doses of MLV distemper vaccine at 12–16 weeks old

Canine Parvo Virus 2 (CPV-2)

• CPV-2 is a highly contagious virus attacking white blood cells and the gastrointestinal tract in puppies, dogs, and wild carnivores.
• It damages the heart muscle in pups and was first identified in 1978
• Variants: CPV2a, CPV-2b, CPV-2c

Susceptibility to Canine Parvo Virus

• All dogs are susceptible, but puppies 6-20 weeks, unvaccinated dogs, and certain breeds have higher risk
• High risk breeds include Rottweilers, Doberman pinschers, Bull terriers, German shepherds, and English springer spaniels

Signs of Canine Parvo Virus Infection

• Signs vary depending on severity: lethargy, loss of appetite, vomiting
• Severe, often bloody diarrhea, abdominal pain and bloating, fever or hypothermia

Canine Parvovirus Severity

• Contact your veterinarian immediately if your dog shows any of the signs
• Persistent vomiting and diarrhea can cause rapid dehydration, damage to the intestines/immune system, and septic shock
• Severe reduction of leukocytes decreases the ability to fight infection and increases the risk of additional infections and possible death within 48-72 hours

Spread of Canine Parvo Virus

• Spreads through direct contact with infected dogs, contact with feces (stool) from infected dogs
• Virus-contaminated surfaces, kennels, food/water bowls, leashes, or hands/clothing of people handling infected dogs can cause spread
• Virus is resistant to heat, cold, humidity, and drying, and can survive in the environment for long periods

Isolation of Infected Dogs

• Highly contagious, dogs suspected/confirmed to be infected need isolation to minimize spread
• Strict infection control protocols are also necessary like cleaning and disinfecting of any areas

Diagnosis of Canine Parvo Virus

• Often suspected based on physical examination and laboratory tests. Fecal testing may confirm the diagnosis
• Fecal ELISA test: most common, ELISA is an acronym for enzyme-linked immunosorbent assay
• ELISA tests usually completed in <15 minutes
• Technicians immobilze antibodies to parvovirus
• Fecal sample is added to the chamber, and antibodies attach to parvovirus proteins that may be present in the stool
• A color-changing chemical is then added to see if parvoviruses have attached to the antibodies
• False positives/negatives are possible, necessitating more testing

Canine Parvo Virus Testing

• Veterinarians may also rely on PCR to diagnose CPV from fecal samples
• CPV fecal PCR test detects small pieces of viral DNA specific to CPV in the stool of an infected dog
• PCR testing is more accurate than CPV fecal ELISA but requires more time
• White blood cell count is often the clincher. Parvovirus infects bone marrow so low white blood cell counts can suggest CPV infection
• Dogs with positive ELISA and low white blood cell count can be diagnosed with a degree of certainty

Treatment of Canine Parvovirus

• Treatment is supportive and manages symptoms, varies depending on how sick the dog is
• Hospital stays are necessary so that the dog can receive intravenous fluids and nutrients to replace loss from vomiting and diarrhea
• Hospital stays utilize an IV drip because the digestive tract of stricken dogs is usually in distress and can’t tolerate or absorb what the dog needs
• Blood transfusions may also be helpful to boost low blood cell counts that may result from CPV infecting the bone marrow
• Antibiotics may be appropriate therapy, administered either intravenously or as injections, to help fight the infection
• Medications to control nausea and diarrhea are also warranted

Canine Parvovirus Treatment Notes

• No specific drug is available which will kill the virus in infected dogs
• Treatment aims to support the dog’s body systems until the dog’s immune system can fight off the viral infection
• Treatment should be started immediately and consists primarily of intensive and supportive care
• Goals of treatment are combatting dehydration, replacing electrolyte, protein and fluid losses, controlling vomiting and diarrhea, and preventing secondary infections
• Sick dogs should be kept warm and receive good nursing care even after aggressive treatment

Canine Parvovirus Outcomes

• Parvo treatment can be expensive, and death may occur despite aggressive treatment
• Early recognition and aggressive treatment are very important in successful outcomes and can approach a 90% survival rate
• CPV-2 is highly contagious so infected dogs must be isolated to minimize spread of infection
• It’s also essential to properly clean and disinfect contaminated kennels and other areas where infected dogs are (or have been) housed
• The virus is not easily killed, so consult your veterinarian for specific guidance on cleaning and disinfecting agents.

Canine Parvo Virus Prevention

• Effective canine vaccinations for CPV have made this infectious disease much less of a threat to dogs
• Vaccination of your dog is an absolute necessity b/c CPV remains remains a serious problem
• Veterinarians usually administer the CPV vaccine as part of a combination shot which includes distemper, canine adenovirus, and parainfluenza vaccines
• These shots are given every 3 to 4 weeks from the time a puppy is 6 weeks old until they are 16 weeks of age
• A booster vaccination is recommended one year later, and then one or three year intervals thereafter

Other Canine Parvo Virus Prevention Measures

• The tiny parvovirus defies eradication and can survive for months outside an animal even through the winter
• Hardy nature of the virus is due to virus resistant to most household cleaning products
• Infected dogs can shed vast numbers of viruses, making it difficult to disinfect an area to an animal once it has been exposed to an infected dog
• Because of infectious potential, isolate any dog that is infected with CPV from other dogs
• As most environments (including dog parks, lawns and even homes) are not cleaned with disinfecting products regularly, a puppy can be exposed to CPV without any warning
• Risk makes vaccine protection especially important vaccine
• Cleaning with a solution of one part bleach mixed with approximately 30 parts water is an acceptable method for disinfecting any indoor area
• Steps used in cleaning indoor surfaces once housed an infected dog include, bedding, food and water bowls, and all surfaces
• CPV loses some of its ability to infect an animal in an indoor environment after one month
• Outside environments contaminated with CPV can be hosed down with rain diluted the virus

Additional Measures to Prevent Against Infection form Canine Parvo Virus

• Exercise caution when bringing puppies to places where dogs gather until they complete their initial vaccination series.
• Limit bringing puppies to spots like pet shops, parks, puppy/obedience classes, doggy day cares, kennels, and groomers
• Choose establishments/training programs that require up-to-date vaccinations, health examinations, good hygiene, and that isolate sick puppies/dogs
• Keeping your dog away from other dogs when it feels sick
• Avoid contact with known infected dogs and their premises
• Keeping your dog away from other dog’s feces
• Routinely collect and properly dispose of your dog’s feces
• Wash hands and change clothes after potentially being in contact with dogs or those exposed to parvovirus

Heartworm (Dirofilaria)

• Mosquito-borne filarial disease capable of causing serious cardiopulmonary disease
• Has no age and breed predisposition, but dogs 3-8 weeks most at risk
• Male dogs are impacted more often than females

Prevalence of Heartworm

• Heartworm is common in tropical and subtropical areas, including:
  • North and South America
  • Southern Europe
  • India
  • China
  • Japan
  • Australia
• Infection rate is higher in dogs that are housed indoors
• Heartworm disease is often referred to as a “slow killer”

Disease Progression with Heartworm in Dogs

• The disease develops slowly, clinical signs often do not develop until many months post-infection
• Clinical progression is due ot initial years for the disease to mature

Canine Heartworm Etiology

• Dirofilaria immitis: a parasitic nematode that primarily affects dogs but can also infect wolves, coyotes, cats, and humans (rare)
• The parasitic nematode is long, slender, white-gray worm that measures 15-30cm
• Final host of the disease are dogs, fox, wild canids, - occasionally cats, and rarely humans
• Spread via transmission to dogs through bite of the bite of an infected mosquito

Canine Heartworm Treatment

• Melarsomine dihydrochloride (Immiticide® or Diroban®) is the gold standard
• Three-dose protocol:
• Initial injection
• Second injection 30 days later
• Third injection 24 hours after the second -Administered deep into lumbar muscles (2.5 mg/kg, 22-gauge needle)

Alternative Slow-Kill Method for Canine Heartworm

• Monthly ivermectin after 30 days of doxycycline
• Pre-Treatment with Doxycycline (10 mg/kg BID for 30 days), combined with monthly ivermectin to kill larvae before melarsomine
• Prophylactic macrolides administered given 2 months before melarsomine to eliminate larvae