Final Exam Flashcards
What are causes of acute colitis in adult horses?
Salmonella Clostridum difficile and perfringens Enterotoxemia Potomac Horse Fever (late spring to early fall) Antimicrobial induced diarrhea
What are causes of acute colitis in foals?
Salmonella Clostridium difficile and perfringens Gastric ulcers Rota virus Compromised GIT Antimicrobial induced diarrhea Foal heat diarrhea Equine proliferative enterotoxemia (L. intracellularis)
What are causes of chronic colitis in adult horses?
Cyathostomiasis
Sand impaction
IBD**
What are causes of chronic colitis in foals?
Villous atrophy (secondary to clostridium) Lactose intolerance
What are clinical signs of acute colitis?
Explosive watery diarrhea Malodorous feces Colic Dehydration (skin tent, prolonged CRT and jugular refill) Depression (electrolyte imbalances in the neurons) Laminitis Anorexia Pyrexia Tachycardia Dry or toxic mucous membranes
In what percent of adult colitis cases is a definitive diagnosis reached?
Definitive diagnosis is obtained in only about 30-50% of cases
Clinical pathology, biochemistry, and hematology abnormalities with acute colitis (same as for salmonellosis)
Leukopenia (left shift, toxic neutrophils, lymphopenia)
Metabolic acidosis (losing bicarb, hyponatremia, hypochloremia, hypokalemia, hypocalcemia)
Increase PCV and lactate
Protein and fibrinogen may be up or down
Azotemia
Salmonella colitis
ALWAYS has to be ruled out due to zoonotic potential and risk of hospital outbreak
Associated patient abnormalities with Salmonella
Acute profuse diarrhea Endotoxemia CV shock Vascular leaking Coagulopathy
Clinical signs of salmonellosis
Febrile
Tachycardic (± tachypnic)
Dehydrated
How can we test for Salmonella?
Multiple culture or PCR as it is shed intermittently, each sample needs to be minimum 5-10g of feces
Treatment and prevention of salmonellosis
Aggressive supportive care Antimicrobials Endotoxemia therapeutic protocol High biosecurity Repeat fecal culture and PCR
Potomac Horse Fever causative agent
Neorickettsia risticii
Clinical signs of Potomac Horse Fever
Biphasic fever
Laminitis
Colitis
Diagnosis of PHF
Paired serum titers and IFAT; confirmation with identification of parasite in WBCs in acute phase
Treatment of PHF
IV oxytetracycline
Supportive therapy
Laminitis prevention (ice bandages)
T or F: There is a vaccine for PHF.
True
Etiology of Equine Proliferative Enteritis
Lawsonia intracellularis
Clinical signs of Equine Proliferative Enteritis
Lethargy Depression Peripheral edema Diarrhea Colic Weight loss
Typical age for horses affected by Equine Proliferative Enteropathy
Young (6 months old)
Diagnosis of EPE
Clinical signs
Ultrasound showing thickening of SI wall
Hypoproteinemia
Positive serology or molecular detection in feces
Treatment of EPE
Antimicrobial (macrolide + oxytetracycline/chloramphenicol) for 2-3 weeks
Correct hydration, electrolyte derangements, and azotemia if present
Etiology of pyogranulomatous pneumonia
Rhodococcus equi
If Rhodoccus equi is causing enterocolitis, where in the GIT is the lesion?
Ulcerative enteritis in the Peyer’s patches of the ileum (may extend to cecum and colon)
Treatment of Rhodoccus equi
Macrolides
Supportive therapy
Clostridial colitis (antimicrobial associated enterocolitis) histories
Farm outbreak in foals
Horse recently treated with antimicrobials
Mares when foal is being treated for R. equi
Untreated horse with diarrhea
Clostridial toxin A does what?
Induces release of substance P (neurotransmitter) at the dorsal root ganglia
This is cytotoxic
Clostridial toxin B does what?
Enterotoxigenic activity and is cytotoxic (necrotizing and hemolytic)
What might be visible on a radiograph of clostridial colitis?
Gas and fluid distended intestine with intramural gas
Diagnosis of clostridial colitis
Quantitative culture (normal flora) PCR
How can we differentiate C. difficile from other clostridium?
Immediate submission of samples
Sending in large samples
Transportation of sample frozen and in air-tight containers
Cytotoxin assay [differentiates from C. perfringens]
Treatment of clostridial colitis
Supportive care
Metronidazole (or vancomycin if resistant to metronidazole)
Which two organisms are more commonly associated with neonatal enterocolitis than with adult acute colitis?
Cryptosporidium spp
Giardia spp
Inflammatory bowel disease is named based on what?
Histopathological findings
Clinical presentation of IBD
Progressive diarrhea Weight loss Good appetite Intermittent colic Dermatitis Peripheral edema (hypoproteinemia)
Treatment of IBD
Steroids
Probiotics
Blister beetle toxicosis is caused by what?
Cantharidin absorption consumed in beetle infested alfalfa
What is the fatality rate of blister beetle toxicosis?
> 50%
How does cantharidin cause ulceration?
It is an irritant causing cell damage and necrosis on contact
What electrolyte derangements associated with cantharidin toxicosis have not been explained?
Hypomagnesemia
Hypocalcemia (may be loosely associated with hypoalbuminemia)
Diagnosis of cantharidin toxicosis via…
Beetle ID
History
Concentration of cantharidin in gastric juice, intestinal content, and urine
Treatment of cantharidin toxicosis
Supportive care Electrolyte supplementation Oral absorbents (mineral oil) Laminitis prevention Endotoxemia treatment protocol
Other things that can cause diarrhea
Acorn toxicity NSAID toxicity Grain overload Intestinal LSA Peritonitis Heavy metal toxicosis Sand colic Enteric pythiosis Anaphylaxis Stress (don't we all know it...)
When treating a colitis patient, after normovolemia has been attained what are two tests that can help us determine adequate fluid delivery?
Serial central venous pressure
Serial lactate
Endoserum (endotoxin neutralizer) is made how?
Horses are vaccinated with a recombinant mutant of S. typhimurium and the antibodies are harvested
How does Polymyxin B work?
Polymyxin B binds to the lipid A region of the endotoxin, thus neutralizing it
What is the most effective NSAID for preventing endotoxin-induced prostanoid synthesis?
Flunixin meglumine
What drug may be beneficial in preventing laminitis?
Pentoxifylline
What are functions of the liver
Process nutrients from food
Store glucose, vitamins, and minerals
Maintain immune function
Remove toxins from the blood
What percentage of the liver has to be damaged for clinical signs to present?
70-80% of the liver being damaged will result in abnormal function or failure
Clinical abnormalities associated with liver damage
Icterus Photosensitization Hepatoencephalopathy Coagulopathies Colic Pruritus Ascites Weight loss Diarrhea Rectal prolapse Fecal color change Dyspnea (pharyngeal or laryngeal collapse)
Clinical signs of acute liver dysfunction
Depression Hepatic encephalopathy Icterus Colic Anorexia
What substance can be used to test the excretory function of the liver?
Bromsulphalein dye
Liver enzymes and how to interpret
SDH: elevation may indicate ongoing parenchymal damage
ALP: not liver specific
AST: not liver specific
GGT: elevation my indicate chronic liver disease
What coagulation factors are produced in the liver?
I, II, V, VII, IX, X
What toxicity and disease have been associated with type III photosensitization in horses?
Pyrrolizidine alkaloid toxicity
Theiler’s disease
Treatment of photosensitization
Eliminate photodynamic agent
Provide cover from the sun
Treat as a skin burn (fluids, electrolytes, antibiotics, anti-inflammatories, pain control)
Hepatic encephalopathy clinical signs
Frequent yawning Abnormal behavior Aimless wandering (apparent blindness) and foot stomping Head pressing Circling Seizures
How might aromatic amino acids cause hepatic encephalopathy?
Increase inhibitory neurotransmitters (GABA and L-glutamate)
Alter catecholamines
Alter MAOs
What drug (and class) improves the neurologic state of hepatic encephalopathy?
Flumazenil (benzodiazepine antagonist)
Etiologies of Idiopathic Acute Hepatic Disease aka “Serum sickness” aka “Theiler’s Disease”
Viral infection with Theiler’s disease
Hypersensitivity type III
Dietary factor (pastured horses)
Pyrrolizidine alkaloid toxicosis
Clinical signs of IAHD
6-8 weeks post-vaccination CNS signs Icterus Yawning (early sign) Photodermatitis Intravascular hemolysis w/ or w/o hemoglobinuria Weight loss Ventral edema
What liver enzyme is helpful to monitor in outbreaks of IAHD
GGT (increased before onset of clinical signs)
Histopathology of IAHD
Hepatocellular central and mid-zonal necrosis
Accumulation of mononuclear cells and neutrophils in the portal region
Bile ductule proliferation
On necropsy, how is the liver of a patient with IAHD often described?
Flaccid liver or “Dishrag liver”
Signalment for cholelithiasis
Middle age to older
No sex or breed predilection
Define choledocholithiasis
Stone found in the common bile duct (most common biliary obstruction in equine patients)
Composition of choleliths includes…
Bilirubin Bile pigment Cholesterol esters Ester of cholic and carboxylic acid Calcium phosphate Sodim taurodeoxycholate
Pathogenic mechanisms proposed for cholelithiasis
Ascending biliary infection (cholangitis) Parasitism (ascarid) Biliary stasis Change in bile composition Foreign body
Clinical signs of cholelithiasis
Colic with pyrexia and icterus ongoing for 2 weeks
Diagnosis of cholelithiasis
Ultrasound (75% diagnosed via this method) of the R 14-16 ICS
Hepatomegaly
Increased hepatic echogenicity
What bacteria can be cultured in cases of cholelithiasis?
Bacterioides vulgatus
E. coli
Histopathology with cholelithiasis
Periportal fibrosis
Bile duct hyperplasia
(Suppurative cholangitis)
Treating cholelithiasis
Medical: -broad spectrum abx -fluids -NSAIDs -DMSO -Diet Surgical: -choledocholithotomy -choledocholithotripsy
With which liver disease can we see moist exfoliative dermatitis and necrotic leathery skin along the coronary band?
Chronic active hepatitis
Moist exfoliative dermatitis: aseptic vasculitis
Treatment of chronic active hepatitis
Supportive care
Corticosteroids (if LPC infiltrate seen on biopsy)
Antimicrobials
Anti-inflammatories
Colchine (inhibit collagen production and reduce inflammation caused by macrophages/cytokines)
Etiology of Tyzzer’s disease
Clostridium piliformis (gram - anaerobic spore forming intracellular rod shaped)
Who is most commonly affected by Tyzzer’s disease
Foals (7-14 d old) ESPECIALLY foals born in the spring
Rapidly fatal
Hematology abnormalities with Tyzzer’s disease
Elevated liver enzymes Severe hypoglycemia (<20mg/dL)
Diagnosis of Tyzzer’s disease
PCR
Necropsy (Warthin-starry stain)
What medications can decrease blood ammonia?
Mineral oil Oral neomycin Oral lactulose Metronidazole Low protein diet and small meals
Atopic dermatitis type of reaction and clinical signs
Type I (IgE) Pruritus, alopecia, erythema, urticaria, papules
Erythema multiforme is death of what type of cells?
Keratinocytes
Where does leukocytoclastic vasculitis occur and what is the age of the patient?
Lower extremities (pasterns) lacking pigment, mature horses
Pemphigus foleaceus definition
Intra-epidermal acantholysis and intracellular deposition of immunoglobulins
With pemphigus foleaceus, what are type of antibodies are involved and what do they target?
Autoantibodies targeting transmembrane proteins (releases proteolytic enzymes which destroy cell attachments causing vesicles and intraepidermal clefts)
How is pemphigus treated?
Immunosuppressives
Pemphigus vulagaris, what immunoglobulin and what is is directed against?
IgG against epidermal transmembrane proteins (same as pemphigus foliaceous)
What is the common name of dermatophytosis?
Ringworm
What is the causative agent of ringworm in horses?
Microsporum equine and Trichophyton verrucosum
How is ringworm spread and what is the incubation period?
Direct contact (or grooming equipment) Incubation period is 1-6 weeks
What is the prognosis of dermatophytosis?
It is a self-limiting infection, lasting 1-4 months
What is the treatment for dermatophytosis?
Topical ketoconazole shampoo
Anti-inflammatory agents
Systemic griseofulvin
Equipment disinfection
What is the common name for dermatophilosis?
Rain rot
What is the causative agent of rain rot in horses?
Dermatophilus congolensis, a gram +, branching, filamentous anaerobic bacteria
What are the three conditions required for development of rain rot?
- Carrier animal
- Moisture
- Skin abrasion
When is dermatophilosis seen most commonly?
Fall and winter months
Where are dermatophilosis lesions located on the patient?
Dorsal aspect
What is the treatment for dermatophilosis?
Remove from wet environment
Remove all crusts
Wash patient with ionophores or lime sulfur
Prescribe antimicrobials
What part of the body is affected by equine staphylococcal cellulitis?
Usually the hind limbs, one limb at a time
Clinical signs of equine staphylococcal cellulitis
Prominent limb swelling, warm and painful to the touch, ± pitting edema Lameness Pyrexia (Lethargy) (Anorexia)
What leads to equine staphylococcal cellulitis?
Injury or trauma (including procedures)
Treatment of staphylococcal cellulitis
Eliminate infection (broad spectrum abx)
NSAIDs (pain modulation)
Hydrotherapy
T or F: surgical debridement is necessary for the treatment of equine staphylococcal cellulitis
If medical management fails, surgical debridement and drainage is necessary
Who is affected by chronic progressive lymphedema most commonly
Draft horses
Where on the patient is chronic progressive lymphedema noted?
Distal limb
What is the causative agent of Pigeon fever?
Corynebacterium pseudotuberculosis (gram +)
Where on the patient are Pigeon fever lesions found?
Pectoral region (rupture in 1-4 weeks)
What is the common name for Pythium infection?
Swamp cancer/Florida horse leech/Kunker
Casused by Pythium insidiosum (protozoa)
Cutaneous habronemiasis lesions are found where
Wound sites
When there is a cutaneous habronemia lesion at the medial canthus of the eye, what is it called?
Dracocystitis
Papillomatosis affects what age group and what is the etiology
Young animals most affected
BPV 1-10
What causes aural plaques
Possibly viral papilloma
T or F: aural plaques resolve spontaneously
F
How are aural plaques treated?
Imiquimod topical
Cryosurgery
How is SCC treated in the equine patient
Surgical excision
5-FU (5-flurouracil)
Intralesional cisplatin
What is the most common tumor in horses?
Equine sarcoids
What organism is associated with pathogenesis of equine sarcoids?
Bovine papilloma virus
What is equine sarcoids?
Fibroblastic tumor, slow growing, no metastasis; NOT a benign tumor
What are the types of equine sarcoids and what do the lesions look like?
Occult (circular alopecia)
Verrucous (sessile or pedunculate)
Nodular (invasive, destroying adjacent tissue)
Treatment of equine sarcoids
PCR for BPV 5-6 on margin after surgical excision Topical caustic ointment 5-FU Intralesional chemo Radiation
Equine melanoma is associated with what horses
Gray horses
Where are melanoma lesions commonly found
Ventral tail, perineum, external genitalia, lip, udder, periocular
Treatment of melanoma
Excise dermal tumors
Cimetidine PO for 16wk
Cisplatin intralesional
How is eosinophilic granuloma diagnosed?
Biopsy histopath reveals collagen surrounded by granulomatous inflammation (eosinophils, lymphocytes, histiocytes)
Who is affected by hereditary equine regional asthenia
QH and related breeds
What is the cause of HERDA
mutation in the pro collagen I N-proteinase (cyclophilin B–PPIB defect)
What is a clinical sign of HERDA?
Skin on back/neck easily torn or stretched (seroma, hematoma)
Equine B cell LSA has been demonstrated to be caused by what?
Estrogen secreting ovarian tumor
What scale is used to body condition score horses?
Henneke (1-9)
