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110 Cards in this Set
- Front
- Back
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What is a common parasitic cause of otitis externa, especially in cats?
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Otodectes cynotis
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Is cytological examination of ear discharge a useful diagnostic test in otitis externa?
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Yes
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When are culture and antimicrobial susceptibility essential diagnostic tests for otitis externa?
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1. When rod shaped bacteria are found on cytology
2. With cases of recurrent otitis that have shown a poor response to therapy 3. If otitis media is suspected |
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A dog is presented for ear scratching. A swab of the ear canal is taken and Gram stained. Gram + bacteria are present. Is this bacteria the cause of the ear infection?
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Maybe - Streptococcus bacteria can be found in a normal ear and also be a pathogen in otitis externa
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What are 2 most common microbes isolated from a healthy dog’s normal ear canal?
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1. Malassezia otitis (yeast)
2. Staphylococcus intermedius (pseudintermedius) |
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What is otitis externa?
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* Acute or chronic inflammation of the epithelium of the external ear canal
* Pinna may be involved * Multifactoral problem |
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What are some predisposing factors for otitis externa?
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1. Anatomic: conformational predispositions of certain breeds
2. Environment: swimming, foreign material 3. Medications: chronic antibiotic and glucocorticoid therapy for yeast infections 4. Hypersensitivity diseases |
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What are some good diagnostic tests for otitis externa?
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1. Otoscopic exam
2. Ear swab (cytology, culture and sensitivity) **** Those are the most practical if problem persists you can do the following 3. CBC and Chem 4. X-ray 5. CT 6. Biopsy |
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What gram + bacteria are most common in healthy dog ears?
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****Staphylococcus (9-20%)
* Streptococcus (16%) *** If abnormally high population could be causing otitis externa |
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3 most common gram - bacteria found in dogs with otits externa?
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* Pseudomonas sp. (20%)
* Proteus sp. (11%) * E. coli (14%) |
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What funji is found commonly in both dog and cat ears?
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* Malassezia sp. (yeast)
** A few yeast is normal but if you see an abundance on cytology it could be the cause of otitis externa |
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What metazoana is commonly the cause of otitis externa in cats?
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Otodectes cynotis
* Can cause problems in dogs but rare |
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What should always be used when taking a sample for an ear culture?
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Individual sterilized otoscope cones
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Which microbe of otits externa can be spread from animal to animal?
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* Otodectes cynotis (cats, dogs, ferrets)
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3 microbes that commonly cause otitis media in large animals?
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1. Mannheimia haemolytica
2. Pasteurella multocida 3. Histophilus somni |
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3 common foot infections in sheep?
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1. Ovine interdigital dermatitis
2. Ovine footrot (contagious footrot of sheep) 3. Strawberry footrot |
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Cause of Ovine interdigital dermatitis
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Fusobacterium necrophorum
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Cause of ovine footrot (contagious footrot of sheep)?
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**Dichelobacter nodosus** plus Spirochetes and Arcanbacterium pyogenes
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Cause of strawberry footrot in sheep?
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Dermatophilus congolensis
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How quickly does ovine interdigital dermatitis resolve?
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Most cases resolve spntaneously in about a week as the immune response overcomes the Fusobacterium necrophrum and its toxin
** Hoof usually not involved |
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What are the general characteristics (gram stain, O2 requirements, spores) of Fusobacterium necrophrum?
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* Gram Neg ROD (pleomorphic filaments)
* Obligate ANAEROBE * Non-spore forming |
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What virulence factors does Fusobacterium necrophrum have?
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1. Lipopolysaccharide (LPS)- endotoxin
2. Cytotoxin- leukotoxin |
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What is the natural environment for Fusobacterium necrophrum?
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Mucus membranes and GI tract
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3 common foot infections in sheep?
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1. Ovine interdigital dermatitis
2. Ovine footrot (contagious footrot of sheep) 3. Strawberry footrot |
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Cause of Ovine interdigital dermatitis
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Fusobacterium necrophorum
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Cause of ovine footrot (contagious footrot of sheep)?
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**Dichelobacter nodosus** plus Spirochetes and Arcanbacterium pyogenes
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Cause of strawberry footrot in sheep?
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Dermatophilus congolensis
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Contagious ovine digital dermatitis is also known as what?
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Ovine footrot
* Cause by Dichelobacter nodosus |
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Gen. characteristics for Dichelobacter nodosus?
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* Gram Neg
* Obligate anaerobe * Non-spore forming |
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Clinical signs of a sheep with ovine footrot caused by Dichelobacter nodosus?
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* Moist, red interdigital area
* Invasion of hoof sole (undermining and separation of hard horn especially from rear) * Foul smell |
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Virulence factors of Dichelobacter nodosus?
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* Adhesin- Fimbriae (higly immunogenic)
* Extoxin- extracellular proteases * Lipopolysaccharide (LPS) endotoxin |
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What is the difference between the virulent and benign strain of Dichelobacter nodosus?
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Virulent strains produce potent extracellular proteases
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What is the major virulent factor for Dichelobacter nodosus?
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Fimbria- it has affinity for interdigital epidermis
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What does the exotoxin (extracellular proteases) of Dichelobacter nodosus cause to sheep foot?
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* Damage to interdigital epidermis
* Cause separation of horn from underlying lamina |
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7 major events for a bacterial pathogen to cause damage to host
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1. Entry
2. Adherence 3. Avoidence of host defenses 4. Multiplication 5. Spread 6. Evasion of host defenses 7. Damage to cells, tissues, and/or organs |
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What predisposes a sheep to foot infections?
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Predisposing conditions are environmental moisture resulting in maceration of the interdigital skin ans sand or stones that may cause mechanical skin damage
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How would a predisposed sheep get a would colonized with Dichelobacter nodosus? Fusobacterium necrophorum?
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* Dichelobacter nodosus from subclinically, acutely and chronically infected sheep
* Fusobacterium necrophorum from the environment |
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How long does it take from infection by Dichelobacter nodosus or Fusobacterium necrophorum to see clincal signs in sheep?
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10 to 20 days
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What are the gen. characteristics of Dermatophilus congolensis (cause of strawberry footrot)?
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* Gram POS rod or filamentous
* Aerobic |
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Reservoir for Dermatophilus congolensis?
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Obligate parasite, so infected animals
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Environment for Dermatophilus congolensis?
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Skin
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5 other diseases caused by Dermatophilus congolensis in large animals
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1. Dermatiohilosis
2. Greasy heel 3. Rain rot 4. Rain scald 5. Lumpy wool |
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Characteristic appearnace of Dermatophilus congolensis under the microscope?
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gram positive with railroad track appearance
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How do you diagnose strawberry footrot caused by Dermatophilus congolensis?
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* Clinical signs- when you peal off scabs there should be a red (strawberry) mark
* Culture- interpretation difficult because contamination by opportunistic and environmental bacteria * Use scabs or crusts for diagnostic testing |
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How do you prevent foot infections in large animal herds?
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* Foot health
* Foot baths * Segregate * Avoidance * Vaccinate * Minimize skin trauma * Antibacterial shampoo *** Dont put treated sheep back on infected pasture |
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3 common foot infections of cattle
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1. Interdigital dermatitis
2. Bovine footrot (bovine interdigital necrobacillosis) 3. Digital dermatitis |
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Cause of Interdigital dermatitis in cattle
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Dichelobacter nodosus
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Cause of bovine footrot
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* Fusobacterium necrophorum
* Prevotella melaninogenica * Arcanobacterium pyogenes |
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Cause of digital dermatitis in cattle
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* Fusobacterium necrophorum
* Prevotella melaninogenica * Spirochetes |
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other names for digital dermatitis in cattle
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* papillomatous digital dermatitis
* hairy heel warts * strawberry foot |
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Surface virulance factor for Fusobacterium necrophorum
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* Cell wall- Lipopolysaccharide
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Secreted virulance factor for Fusobacterium necrophorum
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Exotoxin: cytotoxin - leukotoxin
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Pathogenesis for Fusobacterium necrophorum causing bovine footrot
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1. Disruption of normal skin
2. Colonization of wound 3. Development of anaerobic conditions |
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What term is used to describe any disease or lesion with which for Fusobacterium necrophorum is associated?
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necrobacillosis
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Other common diseases caused by for Fusobacterium necrophorum in cattle
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* necrotic layrngitis of calves (calf diphtheria)
* Necrobacillosis * Necrotic rhinitis |
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What does for Fusobacterium necrophorum cause in the horse hoof?
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Thrush of the hoof
* Localized inflammation, usually hind feet |
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Treatment of digital dermatitis in cattle
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* Debridement of skin flaps and overrun sole horn
* Topical treatments (antibacterial agents) * Foot trimmings * Foot baths |
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Prognosis of digital dermatitis in cattle
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Good with proper care and management
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Complication associated with digital dermatitis in cattle?
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Can progress into distal interphalangeal joint and become septic arthritis
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How long can Fusobacterium necrophorum survive in the soil?
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* Up to 10 months
* Normal constituent of ruminal flora and in the environment |
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How long can Dichelobacter nodosus survive in the environment?
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* Survive warm, muddy environment for 4-14 days
* obligate pathogen of clinically affected or chronic carrier feet |
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Corynebacterium pseudotuberculosis is the causative agent for what disease in horses?
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Pigeon fever
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A Gram stain of a direct smear from a lesion caused by C. pseudotuberculosis would show what?
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Gram-positive pleomorphic rod shaped bacteria that is intracellular
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Corynebacterium pseudotuberculosis is the causative agent for what disease in goats?
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Caseous lymphadenitis
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Although the location of abscesses caused by C. pseudotuberculosis in the horse can be found
anywhere on the horse, where is the most likely location? |
Chest
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Why is it called piegon fever?
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It gets its name from the abscess lumps that often appear on the pectorals, making the horse look
like it has a pigeon's breast. |
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How does a horse become infected with Corynebacterium pseudotuberculosis causing piegon fever?
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* The bacteria enter through skin abrasions and insect bites
* Can also be spread through horse to horse contact, horse to cow contact, through the soil, or through a break in the skin. |
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Geographically where is piegon fever common?
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Pigeon fever is more common in dryer climates and is prevalent in California, but in recent years has
been spreading northward. |
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Is piegon fever fatal in horses?
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Rarely is this disease fatal, but recovery can take months and the disease can reoccur.
** There is no vaccine for this disease, so if a horse contracts pigeon fever, the course of action is to prevent the spread of the infection to other horses. |
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Clinical signs of piegon fever
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* Lameness
* Fever * Lethargy * Weight loss * Very deep abscesses and multiple sores along the chest, midline, and groin area and, sometimes, the back * Abscesses also can develop internally. |
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What is the definitive test to diagnose an infection with C. pseudotuberculosis?
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Culture (isolation)
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How is serologic testing used to diagnose an infection with C. pseudotuberculosis?
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Serological testing is a screening procedure
determining exposure to the bacterium. It does not indicate, however, whether an animal is currently infected or whether it will develop clinical signs of the disease. |
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What neurologic diseases are reportable in horses?
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* EEE, WEE, VEE
* West Nile * Equine Herpes Myeloencephalopathy (EHM) * Rabies |
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What type of virus causes EEE, WEE, and VEE?
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Toga viruses
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What is commonly seen as a result to the toga viruses causing EEE, WEE, or VEE?
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* Perivascular cuffing with mononuclear and neutrophilic infiltrates
* Gliosis * brain and spinal cord affected equally |
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What type of virus causes west nile virus?
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Flavivirus
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What is commonly seen as a result to the flavivirus causing West Nile?
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Nonsuppurative encephalomyelitis
* Spinal cord is more commonly affected |
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What virus causes Equine Herpes Myeloencephalopathy (EHM)?
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Equine Herpes Virus 1
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What is commonly seen as a result to equine herpes virus 1 causing Equine Herpes Myeloencephalopathy (EHM)?
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CNS vasculitis with hemorrhage
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What virus causes Rabies?
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Rhabdovirus
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What is commonly seen as a result to the Rhabdovirus cauing rabies?
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Viral inclusions (negri bodies)
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5 common respiratory signs in horses
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1. Fever
2. Malaise 3. Nasal discharge 4. Cough 5. Dyspnea |
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6 reportable respiratory diseases in horses
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1. Equine Herpes Virus 1&4 (EHV)
2. Equine Viral Arteritis (EVA) 3. Influenza 4. African Horse Sickness 5. Tularemia 6. Glanders |
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Besides respiratory disease, what other manifestations can EHV 1 cause?
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Neurologic disease and abortion
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Besides respiratory disease, what other manifestations can equine viral arteritis (EVA) cause?
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* Edema
* Conjunctivitis * Abortion * Infertility |
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Clinical signs of hematologic diseases in horses?
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* Pallor (anemia)
* Icterus * Pigmenturia * Malaise * Edema * Petechia/ecchimosis |
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4 reportable hematologic diseases in horses
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1. Piroplasmosis
2. Equine Infectious Anemia (EIA) 3. Surra 4. Dourine |
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What infectious agent causes equine Piroplasmosis?
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* Babesia caballi
* Babesia equi ** Causes hemolysis |
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What are the 3 populations of horses that piroplasmosis is commonly seen?
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* South Texas ranch
* Horses imported before Aug 2005 * Racing horses (esp. quarter horse) |
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What type of virus causes EIA?
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Lentivirus
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3 clinical syndromes of EIA
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1. Acute: fever, thrombocytopenia
2. Chronic: weight loss, periods of acute 3. Inapparent |
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What is the trend in the number of cases of pigeon fever seen in horses at Texas A&M?
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Has gone from no cases 4 years ago to about 45 cases this year.
* Increasing each year! |
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How do you diagnose Corynebacterium psudotuberculosis (piegon fever)?
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* Clinical signs/history
* Ultrasound * Synergistic Hemolysis Inhibition Test (>512= internal infection) * Culture |
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How do you treat Corynebacterium psudotuberculosis (piegon fever)?
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* Incision and drainage
* Antimicrobials (internal) |
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How do you prevent Corynebacterium psudotuberculosis (piegon fever)?
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* Dispose of pus
* Manure removal * Insect control |
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2 types of fungi
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Molds and Yeasts
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Molds vs. yeasts
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Molds: Multicellular,m filamentous (fuzzy)
Yeast: Single cell, reproduce by budding |
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When are dimorphic fungi molds? yeast?
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Molds: 25'C
Yeasts: 37'C |
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Transmission of Fusobacterium necrophorum causing ovine interdigital dermatitis
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* Usually occurs when there has been heavy rainfall for several weeks and temperature above 50 degrees F.
** Pathogens are transmitted between sheep via soil contact. |
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Fusobacterium necrophorum zoonotic?
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yes
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What is the reservoir host for the Equine Encephalomyelitis virus?
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Birds
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EEE, WEE, VEE, and WNV are all transmitted via what type of vectors?
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Mosquitoes
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EPM is transmitted how?
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the ingestion of infected opossum feces
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most common infectious cause of cysitis and pyelonephritis in cattle and swine
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Corynebacterium renale
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Corynebacterium renale characteristics
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Gram + rod, piliated, non-motile
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Dysuria
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painful or difficulty urinating, straining
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Pollakiuria
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more frequent voiding of small amount
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Clinical presentation of Cystitis
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* Dysuria
* Pollakiuria * +/- hematuria * +/- pyuria * Distended atonic bladder on palpation with firm thick walls * UA: blood, protein and variable pH * Usually no generalized signs, no fever |
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Stranguria
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painful urging to urinate, spastic dysuria
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Clinical presentation of Pyelonephritis
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* Dysuria
* Pollakiuria * Stranguria * Tail swishing * Treading on hindlimbs * Scalding of the perineum * Distended atonic bladder with firm thick walls * Dilation of the ureter and enlargement of the kidney * Urine reddish-brown in color, cloudy, pyuria, hematuria * UA: more blood and protein than with cystitis and a variable pH * Urine specific gravity low * Presence of bacteria C. renale, E. coli, A. pyogenes * Generalized signs, fever * Usually worse than cystitis |
