Viral, Rickettsial, and Protozoal Skin Diseases Flashcards
What is the meaning of IgM versus IgG titers in toxoplasmosis
If IgM titers are greater than 1:64, this is potentially indicative of active toxoplasmosis infection.
IgG tiers (increased by 4 fold or greater) is indicative of seroconversion, this would be seen I cases where cats have previously been exposed to toxoplasma but they were not actively infected.
Equine VIral Arteritis
Recognized in many parts of the world
Transmission via coitus and inhalation
Caused by an Arterivirus (Arteriviridae) previously classified as a Togaviridae
Reportable in the United States
Affected horses develop edema of the distal limbs (especially pelvic), scrotum, prepuce, ventrum, and periorbital or supraorbital areas; less frequently, edematous swelling on the sternum, shoulder, mammary glands and intermandibular space
Histopathology: lesions in the media of the arteries with well-developed muscular coat
Early changes include fibrinoid necrosis of the media, accompanied or followed shortly by edema and lymphocytic infiltraton
Lymphocytes infiltrate the media and undergo karyorrhexis as well as accumulate in an edematous adventitia
Viral antigen can be demonstrated in affected vessels
Canine distemper is caused by what virus?
paramyxovirus
The classic skin manifestion of distemper is the so-called ‘hard pad disease’, in which the dog develops nasal and footpad hyperkeratosis of varying severity.
IHC detection of canine distemper virus in haired skin and footpad epithelium was reported to be very reliable for the antemortem diagnosis of distemper.
Contagious viral pustular dermatitis (Orf) is caused by what virus?
This disease is primarily found in goats and sheep and is caused by the paradox virus.
humans can get it
What is an acute fatal viral disease caused by an alpha-herpesvirus. Pigs are the main reservoirs of infection. Dogs and cats can be infected by contact with an infected animal or, more typically, by eating raw pork products.
Pseudorabies
Common clinical sign is ptyalism - followed by restlessness, ataxia, anorexia. If pruritus is present, its usually the head and ears that are mostly affected. Mainly neurological signs in cats.
Confirmed with virus isolation.
Feline rhinotracheitis is caused by what virus?
It is caused by a feline alpha-herpes virus-1 and is a double stranded DNA virus with glycoprotein-lipid envelope.
The major of recovered cats are latently infected and have virus preset in their trigeminal ganglia.
The virus can be seen in keratinocytes using electron microscopy.
A unique feature on biopsy is necrosis of the epitrichial sweat glands.
PCR is VERY accurate (highly sensitive and specific)
What is a small, unenveloped, single-stranded RNA virus belonging to the genus Vesivirus. Many different strains of this virus exist. Cats can be sequentlly infected with different strains, with varying degrees of clinical illness. Prevalence is highest in multicast households.
Feline calicivirus
This virus is shed in ocular, nasal, and oral secretion and ornery spread by direct contact with an infected cat. Vaccination produced protection against disease caused by most commons trains (FCV-F9, FCV-255) - it doesn’t prevent infection or common carriage.
What are the most common clinical signs associated with FCV infections?
Oral vesicles, ulcers, depression pyrexia, sneezing and conjunctivitis with ocular and nasal discharges. Ulcers are frequently found on the tongue and may also be present on the lips, gingival mucosa and nose.
Chronically infected cats may develop lymphoplasmacytic gingivitis sand stomatitis; this is especially common in cats that are co-infected with FIV.
Some stains have an affinity for joints, resulting in lameness that resolves after a few days.
A severe hemorrhagic and highly virulent biotype of FCV has emerged.
What is a small double-stranded DNA virus that infects many different animal species? They are usually species specific and belong to the Papovavirus family. Six different syndromes have been associated with these infections in dogs.
Papillomavirus infection
Papillomaviruses infection keratinocytes in what layer of the epidermis, undergo genome replication in what two layers of the epidermis and where does this virus release new infectious virus in keratinocytes squames?
Papillomaviruses infect keratinocytes in the stratum basal, undergo genome replication in the spinous and granular layers, and release new infectious virus in keratinized squames.
Cytopathic effects include increased mitotic rate resulting in acanthoses and hyperkeratosis, formation of koiliocytes in the upper stratum spinosum and giant keratihyalin granules in the stratum granulosum.
What are keratinocytes with clear cytoplasm and pyknotic nuclei associated with papilomavirus infections?
koiliocytes
Describe the pathogenesis of papillomavirus regression in lesions skin?
Although antibodies are produced, cell-mediated immunity is more important in the regression with CD4 cells producing cytokines to activate macrophages that inhibit viral replication, and kill infected keratinocytes.
What macrolide antibiotic has been shown to sometimes be effective in the treatment of both oral and cutaneous papillamatosis in dogs?
Azithromycin
The mode of action in the treatment of papilloimatosis has bot been elucidated.
Exophytic cutaneous papillomas occur more commonly in older dogs. What two breeds may have an increased incidence?
Kerry blue terrier and cocker spaniels
Cutaneous inverted papillomas are small, form, raised masses that appear as cup-shaped lesions with small pore opening at the skin surface, Affected dogs may be multiple lesions where? What breeds have an increased incidence?
ventral abdomen
Beagles, Bernese Mountain dogs, cocker spaniels, Great Danes, Irish Setters, Kerry blue terriers and whippets.
Canine viral plaques are most common in what two breeds?
Miniature Schnauzers and pugs (autosomal dominant?)
The majority of feline fibropapillomas (sarcoids) have been positive on PCR for papillomavirus, with strong similarity to which virus type?
bovine papillomavirus type 1
Why can’t 5-fluorouracil be used on cats for bowenoids in situ carcinomas?
neurotoxicity
Rocky Mountain Spotted fever is caused by what rickettsial agent and is transmitted by which ticks?
Rickettsia rickettsia and is transmitted by Dermacentor andersonii (Rocky Mountain Wood tick) and Dermacentor variablis (American Dog tick).
Approximately 20% of dogs will develop skin lesions
Edema of the extremities is frequently seen and may the the realist cutaneous signs. The epidymus of the male dogs may be painful and woolen.
Biopsy reveals necrotizing vasculitis.
Ehrlichiosis is caused by the tick-trasntitted gram-negative obligate intracellular bacterial agent ____. Originally classified as a rickettsial organisms, recent molecular analysis has shown that Ehrlichia being to the family ______.
Ehrlichia canis
Anaplamataceae.
Skin lesions are very are rare and include a crusting facial dermatitis involving the bridge of the nose, pustular and purpuric lesions due to vasculitis and an intensely pruritic papulocrustous dermatitis.
How do you diagnose Ehrlichia?
Diagnosis is based on findings of thrombocytopenia, anemia, leucopenia, hyperproteinemia, hyperglobulinemia, finding either morulae in leukocytes or positive results on serology (IgG > 1:80).
What is the arthropod vector for Ehrlichia canis?
Rhipcephalus sanguineous - Brown Dog Tick
Feline hemotrophic mycoplasmosis (aka feline infectious anemia) is an acute or chronic disease of domestic cats. It is characterized bu severe, depression, anorexia, and macrocytic hemolytic anemia. What is the causative organism?
Haemobartonella felis
What is an obligate intraceullar coccidian parasite where cats are the definite host and excreted infectious oocyst in their feces. Most cats and dogs become infecting by infesting the intermediate hosts (small mammal) continuing the encysted bradyzoites?
Toxoplasnosis- Toxoplasma gondii
Nodular pyogranulomatus dermatitis has been reported in dogs and cats developing disseminated toxoplasmosis.
How do you diagnose toxoplasmosis?
Cytologic analysis of fine-needle aspirate fro nodules may demonstrate the presence of protozoal organisms inside macrophages.
PCR-based techniques are available.
Paired serum samples showing a fourfold rise in titer over 2 to 3 weeks.
What disease has a complicated life cycle involving coccidia infection affecting rodents, reptiles and raptors. Infection occurs by ingestion of an infected host and results primarily in diarrhea?
Canine caryosporosis
What is the definitive host for Neospora caninum? What are the intermediate hosts?
The definitive host are dogs and coyotes which shed the oocytes for several months following ingestion of N. caninum-infected tissues.
Intermediate hosts include cattle, diet, dogs, goats, horses and sheep.
Infection in pregnant animals usually leads to abortion.
What are the most common clinical signs of Neosporosis?
Dogs of any age can be infected, but clinical signs are more severe in young dogs,Neurologic and muscular signs predominate, but pneumonia, hepatitis, myocarditis or dermatitis can also be seen.
Skin disease has been described in small number of dogs. Most had widespread draining nodules
How do you diagnosis Neosporosis?
Histologically, nodular lesions are characterized by pyogranulamatous dermatitis. Tachyzoites can be seen within keratinocytes, macrophages, neutrophils and rarely in endothelial cells.
To differentiate from toxoplasmosis, IHC, or PCR are needed.
A titer of greater than 1:8000 by indirect fluorescent anitbody testing is considered strongly suggestive of active infection.
GSD, GSP, Labs and goldens, boxers, bassets and greyhounds.
**A strong statistical correlation has been found between infections on dairy herd and the density of dogs on the farms.
How do you treat Neosporosis?
Dermatitis and myositis can be treated with clindamycin
If neurologic disease is present, TMS should be used due to better penetration into the CNS.
Infected bitches will transmit the disease repeated through successful litters and therefore should not be bred.
Sarcocystis dermatitis has been reported several times in which breed?
Rottweilers
Canine babesiosis (piroplasmosis) is a tickbourne disease caused by the hemoprotozoan parasite of the genus babes. These organisms primarily cause ____ destruction.
erythrocyte destruction = anemia
The two species causing disease are Babesia canis (more common in Gulf States) and Babesia gibsoni.
Babesia canis = Greyhounds (Florida) - titers 1:80 are diagnostic
Babesia gibsoni = Pitbulls (fighting dogs) - titers 1: 320 are diagnostic
Skin lesions are uncommon and due to leukocytoclasic vsculittis with or without vascular necrosis.
How is Leishmaniasis transmitted to humans and animals?
It is transmitted by bloodsucking sandlots of the genus Lutzomyia in the New world and Phlebotomus in the Old World.
The frequency of infection increasing during warm months with the vector load is high.
What is the reservoir for Leishmania?
Domestic and wild dogs, rodents, and other wild mammals are th reservoirs.
20% of seropositive symptomatic dogs have Leishmania organisms in clinical normal skin.
How long is the incubation period for Leishmania?
It varies from weeks to several years with a gradual onset of signs and continual progression.
Dogs can be infected at any age, but the prevalence of infection has a bimodal distribution, with a first peak in dogs younger than 3, then a second peak between 8 and 10 years of age.
What breeds appear to be predisposed to developing Leishmaniasis?
German Shepherd and Boxers may has an increased risk.
What is the most common clinical sign of Leishmaniasis?
The most common finding is an exfoliate dermatitis with salivary white asbestos-like scaling. Exfoliation can be generalized but usuallyy is most pronounced on the head, pinnae and extremities.
Nasodigital hyperkeratosis may accompany scaling and involved skin can be hypotrichotic to alopecia.
Periocular alopecia (lunettes) is common.
The next most commonprjsentation is an ulcerative dermatitis.
Generalized lymphadenopathy and hepatosplenomegaly, renal failure are common.
Describe the immunologic response to Leishmaniasis
Dogs with Leishmaniasis show an immunologic response to the organisms. Resistance or susceptibility to clinical leishmaniasis appears to be associated with stimulation of Th1 or Th2 cell response. IL-2 and TNFa seem to play a protective role. With infection, serum levels of anti-Leishmania IgG, IgM,IgA and circulating immune complexes increase and with high titer predisposing to renal disease.
With infection, the number of CD21, CD5, CD4 and CD8 cells decrease and the degree of incompetence seems to influence the severity of clinical signs.
With persistent cell-mediated response, the dogs clinical signs are absent or milder, and the number of organisms found in the tissues is fever.
Describe the cytology of Leishmania
Amastigoes can be detected within MACROPHAGES in the affected tissue.
Amastigotes are easiest to detect using Geimsa stain and are most often found in smears from lymph nodes and bone marrow.
Although Leishmania is visible in routine stains, Leishmania organisms are best seen when what stain is used?
Geimsa
IHC techniques facilitate identification of the organism.
Can you culture Leishmania?
Specialized labs utilizing blood agar -based media cultures proceed the most specific assay fro Leishmania through demonstration of promastigotes. However, limited availability and long incubation time (30 days) limit the use of this diagnostic method.
Which method of PCR for Leishmania has the highest specificity?
Quantitative PCR
It’s also useful in monitoring effectiveness of treatment.
Bone marrow/LN > skin > conjunctiva > buffy coat > whole blood
Fresh tissue is always better!
Which test for Leishmania has been recommend by The Who for Animal Health as the reference serologic method?
IFAT - immunofluroesence antibody test
False positive tests are due to cross-reaction with Trypanosoma Cruz.
ELISA and rapid ICS can differentiate between those two organisms BUT the testing is less sensitive than IFAT.
How do you treat Leishmaniasis?
This is basically an incurable disease.
Megluamine is the commonly used for the treatment of Leishmaniasis in dogs and humans. Transient elevation of ALT and amylase may occur with treatment once daily for a month. It reduces the parasite load, increases Leishmania-specific IgG and improved the cell-mediated immunologic response.
You can add in Allopurinol. Longer period of clinical remission than when treated with wither drug as a single agent.
Aminosidine (paromomysin) is a FDA-approved ____ for the use in dogs with Leishmaniasis, it has both antimicrobial AND antiprotozoal activity. Side effects can include renal and vestibular damage.
aminoglycoside
What are the effects of Marbofloxacin on Leishmania?
Marbofloxacin is a third generation synthetic fluoroquinolone. It has direct TNFa and indirect (generation of NO) abasing Leishmania. Enrofloxacin may also enhance macrophage killing of Leishmaniasis through NO generation.
Which two parasiticides have NO effect on sandflies?
pyriprole and metafluminzone
Canine leishmaniasis by what species of Leishmania?
L. infantum (syn. L. chagasi) with zoonotic potential, and dogs are the main reservoir
In susceptible dogs a humoral response cannot provide protection against parasites, whereas in resistant dogs ___ dominates and cytokines secreted by activated T cells induce macrophage activity and intracellular parasite elimination due to the production of nitric oxide
Th1
What is a oncogenic immunosuppressive virus. It can induce skin tumors (lymphoma, fibrosarcoma); however, most commonly affects the skin by its cytosuppressive actions.
feline leukemia virus (FeLV)
Clinical signs may include chronic or recurrent gingivitis or pyoderma, poor wound healing, seborrhea, and generalized pruritus.
FeLV-infected cats have an increased susceptibility to generalized dermatophytosis, demodicosis, Malassezia dermatitis and bowenoid in situ lesions.
**cutaneous horns and giant cell dermatosis are additional cutaneous syndrome associated with FelV
Biopsy of FeLV-associated cutaneous horns contain scattered brightly eosinophilic keratinocytes, some of which are apoptotic, mutinucleated and vacuolated. IHC may be able to demonstrate the presence of what within the lesions?
gp70 positive FeLV antigens with lesions
FeLV-associated _____ dermatosis is a rare pruritus crusting dermatitis. the lesions are scaly, erosive, crusted and vary in distribution. All cases have some involvement of the face or head, either around the lips or perioral skin, pinnae or preauricular skin.
giant cell dermatosis
Cats at presentation are otherwise healthy.
On histopath, the epidermis is hyperplasic and heavily crusted. The characteristic feature is syncytial-type giant cell formation in the epidermis and ORS to level of isthmus. Keratinocytes within and around the giant cells are apoptotic.
What is the most common clinical signs of FIV?
The most common clinical sign is chronic or recurrent oral disease (gingivitis). They may also be at an increased risk for developing bowenoids in situ lesions and mutliple mast cell tumors.
What virus has been incriminated in muliticentric fibrosarcomas in young cats and also with the development of liposarcomas in kittens?
Feline sarcoma virus infection
Infections of Poxvirus in cats is most common during the summer and fall months, coinciding with the peak population of the _____ host.
rodent; cats typically become infected from wound inflicted while hunting rodents.
The primary skin lesion is generally a single ulcerated nodule not he head, neck or foreleg.
A leukocyte-associated viremic period occurs 1 to 3 weeks following the initial infection.
Feline cowpox (orthopoxvirus) has zoonotic potential for contact in cats, dogs and humans.
For diagnosis of poxvirus in cats, what is found within keratinocytes of the epidermis, hair follicles and sebaceous glands?
Eosinophilic intracytoplasmic inclusion bodies
What is the preferred method of making a precise diagnosis of cowpox infection in cats?
Virus isolation or PCR analysis are the preferred methods.
Contagious viral pustular dermatitis is caused b what virus?
Caused by Parapoxvirus ovis, it affects sheep, goats, and camelids. It typically occurs in young animals (2-4 months of age) and is due to contamination of skin abrasions. Lesions consist of pustules and vesicles that progress to heavy dark yellow to brown or black crusts around the lips and nostrils; this can result in transmission to teats via nursing. The lesions can be painful and lead to reduced feeding behavior. Lesions on other body regions (oral cavity, interdigital spaces, coronary bands) can also be affected. Typically lesions are self-limiting in 2-3 weeks though a chronic form that lasts weeks has been reported. This virus is zoonotic. In humans it has been called orf.
Cowpox (Feline cowpox) is caused by what virus?
An orthopoxvirus (same family as human smallpox), endemic in Europe and Asia, rodents are reservoir host, rarely produces disease in cattle but causes disease in cats, occasionally humans, has been reported in a dog. Clinical signs include ulcerated plaques and nodules, typically on the head/neck/forelegs (body regions exposed to rodents). There is usually no pruritus associated with the skin lesions. Other clinical signs are uncommon but can include fever, decreased appetite, oral/gastrointestinal ulceration, diarrhea, nasal discharge, pneumonia. Typically resolves without treatment in 6-8 weeks in an otherwise healthy animal, but viral co-infections or immunosuppressive therapy can lead to fatal pneumonia.
Describe the different variants and clinical signs of Bovine Papilloma virus
BPV-1: teat fibropapillomas - Sarcoids
BPV-2: head/neck/shoulder fibropapillomas - Sarcoids
BPV-3: ‘atypical’ warts, all ages, low, flat circular non- pedunculated, do not regress
BPV-5: ‘rice grain’ warts on teats, all ages, do not regress
BPV-6: conical to branch-like warts on teats with long surface projects that frequently break off, leaving ulcers behind, do not regress
BPV-7, 8, 9, 10, 11, 12, 13: no useful clinical information
