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5 Viral Respiratory Diseases of Horses
1. Equine Influenza
2. EHV (Rhinopneumonitis)
3. EVA
4. Equine Adenovirus
5. Equine Rhinovirus
Transmission of EI
Envelope in EI contains...
Contains Neuroanimnase and Hemmagglutin
Rare sequele to EI
Why do you always have to update vaccines with EI?
Antigenic Shift
EI: more severe in young or old?
Diagnosis of EI
1. Virus Isolation
2. FA or ELISA
3. Serology (4 fold incr.)
common sequele to EI
Post Viral Allergic Pneumonitis: chronic pneumonitis, COPD, bact. and guttural pouch infections, bronchitis and pneumonia
How often do you vaccinate against EI?
Every 3-4 months
Booster 2-4 wks before show because if only 10 days or less then could have transiet dz.
Transmission of EHV
Inhalation or Ingestion
MC age for EHV
Stain of EHV that can cause abortion and CNS signs
Dx of EHV
Virus Isolation
FA Stain
(note: ELISA can't disting. between EHV 1 & 4
When to vaccinate pregnant mares against EHV?
5,7, 9 months gestation
How often to vaccinate foals against EHV?
Every 3 months
EVA is most prevelent in this breed?
Transmission of EVA
Respiratory Secretions and Venereally
Carriers of EVA
CS are febrile, serous nasal discharge that may become purulent, leukopenia, pharyngeal lymphoid hyperplasia, abortions and CNS signs
CS are acute onset of fever, coughing and nasal discharge
CS are fever, limb edema and stiffness, palpebral edema, rhinitis, conjunctivitis, urticaria, papular eruptions on muc mem., abortions
What 3 things do you worry about in an overweight horse?
1. Lipidosis
2. Laminitis
3. Arthritis
What 3 things do you worry about in an underweight horse?
1. Not enough feed
2. Parasites
3. Teeth
where do teeth get sharp on the maxilla?
on the mandible?
buccal surface on the maxilla and lingual surface on the mandible
(on the top the teeth are sharp on the cheek side and on the bottom the teeth are sharp on the tongue side)
EHV-1 Causes
EHV-2 causes
EHV-3 causes
Coital Exanthema
EHV-4 causes
Respiratory probs
Exuberant Granulation Tissue aka
proud flesh
cause of proud flesh?
poor wound management
An inflammatory response involving the DORSAL lamina of the hoof
4 Causes of Laminitis
Carb overload
Retained Placenta
Excessive Work or Stress
Stance with Laminitis
Sawhorse Stance: rear limbs are placed under body
With Laminitis, where is the positive hoof test at?
The Toe
MC place for laminitis to occur?
Forelimbs (toe pain)
Chronic CS of Laminitis?
Feet Cool to the Touch
No digital pulse
Dropped Sole
Diverging Hoof Growth Lines
Rotation on P3
Dx of Laminitis?
Rads showing rotation of P3
Nerve Block that shows improvement
Nerve Block to Dx Laminitis?
Palmar Digital Nerve Block
Tx/pain relief for acute laminitis?
Bute, Banamin
Frog Support used with Acute Laminitis?
Lily pads
Heart Bar Shoe
Way to reduce stress on lamina with laminitis
Wedge pad heel that reduces the pull of the DDF
Vasodialators used with Laminitis?
Nitroglycerin Patches
Why is heparin used to treat laminitis?
Activates reticuloendothelial system
Decreases clotting in foot microvasculure
Used to reduce inflammation in laminitis?
General Treatment for Acute Laminitis?
Pain Meds, Frog Support, Heels that reduce strain on DDF, Vasodialators, Heparin, Anti-inflammatories
Surgical Treatment for Chronic Laminitis?
1. Dorsal Hoof Wall Resection
2. Full thickness hoof wall resection
3. DDF Tenotomy
4. Inferior Check Ligament Desmotomy
Dorsal Hoof Wall Resection
remove toe and reshape hoof parallel to P3
Full thickness hoof wall resection
drain necrotic debris, allows for new hoof growth
DDF Tenotomy
For pasture soundness only
Inferior Check Ligament Desmotomy
Reduces the pull of the DDF

Allows for an athletic career
MC cause of lameness
Subsolar Abcess
cause of subsolar abcess
1. Puncture wounds at the frog
2. Puncture wounds at the white line from gravel
where do puncture wounds at the frog drain?
At the heel between the sensitive and insensitive frog
where do puncture wounds at the white line drain?
At the coronary band
Tx of Subsolar Abcesses?
Estab. Ventral Drainage
Maintain Drainage with Epson Salt and Ichthammol
Antibiotics in foals
Mares repro barriers
1. Vulva lips
2. Vestibular Sphincter: vulvovestibular junction
3. Cervix
Normal Vulvar Conformation
The dorsal commisure of the vulva should be even or tightly below the bony floor of the pelvis
pustules or ulcerations on the labia of mares or the penis of stallions
Equine Coital Exanthema
safe to breed horse with Coital Exanthema when?
3 weeks after lesions go away
Treat Melanoma (small nodules that can metastisize) of the vulva with?
Treat ACC (granulomatous or plaquelike lesions, rarely metastisizes)
MC psuedohermaphrodite?
Male Psuedohemaphrodite: Hypoplastic testicles, elongated rudimentary vulva with penile homologue instead of clitorus, XX, male behav
Location of Persistant Hymen?
Vulvovestibular Junction
Tx of Persistant Hymen?
should be broken down to allow fluid to exit, can breed 2-3 wks later
First Degree Perineal Laceration
Laceration thru the dorsal vulvular commisure and mucosa of the vestibule
Tx for Primary Perineal Laceration
Second Degree Perineal Laceration
Laceration thru the dorsal vulvular commisure, vestibular mucosa, submucosa, muscular layer
Third Degree Perineal Laceration
Laceration thru the rectal floor, vestibular ceiling, and anal sphincter
Vericose Veins in the Mare?
Chronic slow loss of blood from the vulva late in gestation
Tx for vericose veins in the mare?
Can be surgically ligated
Cause of urine pooling?
During estrus, the cervix relaxes and uterine tone decreases so urine pooling can occur
Urine Pooling can cause these 3 things?
1. Endometritis
2. Vaginitis
3. Cervicitis
Treatment for urine pooling?
Flush large volumes of saline or antibiotics before cover, Caslicks, or surg correction with a urethral extension
Asending infection can result in endometritis
Uterine Infection
Desending infection
Benign Portions of mesonephric tubules may be a rare cause of secondary infections
Gartner's ducts
Dx degnerative uterine disease
Endometrial biopsy
Seen on endometrial biopsy with degen uterine dz
1. Glandular degen
2. lymphatic abnorm
3. endometrial atrophy
4. endometrial cysts
Uterine Neoplasm (rare)
Caused by contamination after breakdown in uterine defense mechanisms due to breeding, examination, and poor perineal conformation
Uterine Defense Mechanisms
1. Uterine Contraction
2. Phagocytosis by neutrophils
3. Repro anatomy barriers (vulva, vestib sphincter, cervix)
MC cause of endometritis
Streptococcus zooepidemicus
Absolute prognostic indicator of active inflammation
Presence of neutrophils in the lumen when doing endometrial cytological eval.
Seen on ultrasound with Endometritis
Demonstration of uterine fluid by ultrasound (7-12 days after ovulation)
Tx of Endometritis?
Lavage enhanced by Oxytocin
Antibiotic therapy
Reportable venereally transmitted bacterial endometritis
Contagious Equine Metritis
Etiology of CEM
Taylorella equigenitalis
Asymptomatic carrier of CEM
Discharge with CEM
Copious Grey Exudate for short duration
CEM is localized in the mare where?
the Clitorus
Media to grow CEM
Chocolate Agar
Tx for CEM
Scrub clitorus with chlorhex then pack with nitrofurazone or chlor hex ointment
Cervix location during Diestrus
Closed and lies in the middle of the cranial face of the vagina with a round rosette appearance
Cervix location during Estrus
Softens and opens, dropping toward the vaginal floor as it relaxes
when are pregnancy losses the greatest in the mare?
before day 35 (before the embryo enters the uterus)
Pediculosis aka
Sucking Louse found on the mane, tail, and distal legs
Haematopinus asini
Biting louse found on the dorsolateral trunk
Damalinia equi
Season that lice is most common?
Dx lice
acetate tape
Psoroptic aka
Body Mange
Psorpties equi
Otitis Externa
Psoptes caniculi or hippotis
Quarantine how long with psoroptic mange?
7-12 wks
Tx for psoroptic mange and sarcoptic mange
Don't use this in the horse for mange because it causes depression, ataxia, and progressive large intestinal impaction
Rare, reportable mange in horses that has been eradicated?
Sarcoptic mange
Chorioptic mange aka
Leg Mange
Quarantine for how long with chorioptic mange
10 wks
Causes pruritis, erythema, alopecia and crust formation along legs
Chorioptic mange
MC breed affected with Chorioptic mange: feathers in fetlock region
Draft horses
Chorioptic: surface mange or deeper?
Etiology of demodex in horses?
Demodex caballi and equi
Rare mange associated with immunosuppressive conditions or therapies?
Trobiculosis aka
Free living larva that normally feed on small rodents: associated with pruitic papules and wheals on horses
Dx Chiggers?
Colorful larvae id in the center of a wheal or papule
More common in cows, but seen in horses that live close to cows
Hypodermiasis aka?
stage of warbles that penetrate the skin and produce a breathing hole?
CS: SQ nodules and cysts over the dorsal back
aka for summer sores
Etiology for Habronemiasis
Habronema musca
Drashia megastoma
Summer sores life cycle
Adults live in the stomach
Eggs and larva are passed in the feces
Ingested by maggots of flies
Flies deposit larva on horse mouth
CS occur when the larva are deposited in other places (prepuce)
Summer sores may cause this reaction
Common findings with habronemia
Nonhealing wounds
Proud flesh (exuberant granulation tissue)
Discharge and granules with habronemia?
Serosanginous or hemorrhagic

Yellow granules
DX habronemia?
id larva on granule exam or tissue biosy
Onchocerca of nuchal ligament
O. gutturosa
Onchocerca of CT of flexor tendons and suspensory ligaments of the fetlock
O. reticulata
Onchocerca of the funicular portion of the nuchal ligament
O. cervicalis
Intermediate host for Onchocerca
Cullucoides gnats
Onchocerca: hypersensitivity to the microfilaria along the ...
the *ventral midline*, face and neck
ocular lesions with Onchocerca
keratitis, uveitis, peripaular choroidal sclerosis
depigmentation of the bulbar conjunctiva
Dx of Onchocerca
Micro exam of skin biopsy with an eosinophilic granulomatous reaction to the parasite around the microfilaria
Oxyuriasis aka
where does pinworm adult female lay her eggs
out of the horses anus
CS of pinworms
Rubbing tail on fence posts, trees, etc
Dfdx of pinworms (4)
1. Food allergy
2. culicoides hypersensitivity
3. lice
4. stable vice
Premature/dysmature foal
any sick foal
barker foal, hypoxiod ischemic
Neonatal maladjustment syndrome
lymphopenia, decreased IgM, lymphoid hypoplasia
Combined immunodeficiency
COPD aka
Allergic Airway Disease
COPD signs can appear after this vaccine
Flu vax
COPD: allergy to...
spores of hay molds=indoor
pollens in pasture=outdoor
type of dyspnea due to bronchitis from COPD
Expiratory dyspnea
heave line is hypertrophy of these muscles
External abdominal oblique
Seen on TTW with COPD
Healthy neutrophils (segs)
lg amnt of mucous
(curschmann's spirals)
response to this with suspected COPD means postive dx
atropine or glycopyrolate
Corticosteroids (dex, triamcilinolone, beclamethasone)
Bronchodialtors (brethine, clenbuteral, albuterol)
Hyposens test
Infectious degen disease of the frog that results in black necrotic material in this region
Thrush associated with these 3 things..
1. filthy stalls
2. failure to clean frog reg.
3. lack of frog pressure
Tx of Thrush?
Debride diseased frog
Pick feet daily
Mild Antiseptics
Shock aborber between cartilage and cortical bone
Subchondral bone
_________(incr. or decr) PG's and HA's with Arthritis
_________(incr. or decr) vol., protein count with Arthritis
Configuration of collagen fibrils with arthritis
Arthritis: inflamm. induces
Cytokines, kkinins, PG E, thromboxanes, leukotrienes, and prostacycline
Synovial fluid analysis with aseptic arthritis
total leukocytes: norm or slightly elevated
increased lymphocytes
increased protein
Synovial fluid analysis with septic arthritis
Predominance of segmented neutrophils
Pathogneum of septic arthritis
Segs greater than 30,000 in synovial fluid
Seen with septic arthritis on rads
subchondral bone reabsorption
periosteal bone formation
uses 90m-methylene diphosphonate isotope and reflects relative blood flow in tissue
Neuclear scintigraphy
Tx of Arthritis
Antiarthritics like PSGAG's (adequan)
joint lavage
Ocular trauma can result in
How much of their body wt shuld foals consume in a day?
Uses to assess malnutrition
If foal can't suckle, how do you feed
Nasogastric tube
Why shouldn't you force feed with foals?
Aspiration pneumonia
Common condition associated w/ severe straining or tearing of flexor tendons
Bowed Tendons
Causes of Bowed Tendons
1.Hyperextension of the fetlock
2.Trauma w/ exercise
3.Muscle fatique w/ exhaustion
4.External trauma
5.Improper bandaging
MC Cause of Bowed Tendons
Hyperextension of the fetlock
3 types of Bowed Tendons
1.High bow – w/in carpal sheath
2.Mid bow – between carpal and digital sheaths
3.Low bow – caudal to P1
MC limbs for bowed tendons
rule outs for bowed tendons
Cellulitis and suspensory desmitis
Immed tx for bowed tendons
1.For three days
2.Ice 20 minutes every 6 hours
5.Stall rest
7.Poultice bandages
Follow up therapy for bowed tendons
1.U/S 4 days post injury and then every 30 days
2.Stop DMSO and possibly bute
3.Stall rest until heat is gone
4.Support bandages and controlled hacks for 4-8 weeks
Surgical treatments for bowed tendons
1.Proximal check ligament desmotomy
2.Tendon splitting
3.Volar ligament transection
Tendon splitting
Allows for collagen reconstruction of core tendon- In association w/ proximal check desmotomy
Volar ligament transection
-SDF tendinitis-Restricted movment of SDF through fetlock canal- Notching of sheath over volar annular ligament
prognosis with bowed tendons
20% return to previous level of training
aka lumpy wool and Strawberry fot rot, cutaneous streptotrichosis, rain rot, rain scald, dew poisoning
Dermatophilosis etiology
Dermatophilus congolensis
Infection of the epidermis characterized by exudative dermatitis w/ scab formation
·Seen in cattle, sheep and goats most commonly (occasionally horses)
causes of Dermatophilosis
Prolonged wetting by rain, high humidity, high temp and flies and ticks can increase it
Dermatophilosis: how do scabs look?
Scabs look raised and circular
Dermatophilosis: Lumpy wool
pyramid-shaped masses of scabs on wool
Dermatophilosis:· Strawberry foot rot
skin from coronet to carpus or hock
Tx of Dermatophilosis
PPG or streptomycin injections
where is dermatophysis seen?
·In horses it is seen on the rump, limbs and face
Bacterial pneumonia in foals: common primary
Primary – Streptococcus zooepidemicus and Rhodococcus equi
Bacterial pneumonia in foals
Secondary to sepsis
E coli, Actinobacillus equuli & suis, Klebsiella pneumonia, and Salmonella
Bacterial pneumonia in foals
Secondary to virus
Influenza, EAV, EHV-1,2,4, or Rhino
Bacterial pneumonia in foals
Others often seen in combination with above organisms are
Pasteurella multocida and Bordetella bronchiseptica
bacterial pneumonia of the foal caused by
overcrowding, poor housing, transportation, rough handling, inadequate nutrition, dehydration, poor ventilation, FPT, poor vaccination of mare
Clinical signs of bacterial pneumonia of the foal
a.Fever – early
b.Resp rate > 30 bpm
c.Flared nostrils, exaggerated rib movement and abdominal effort
d.Exercise intolerance, cyanosis, weakness and reluctnce to move – esp R. equi infection
e.Mucopurulent nasal discharge
f.Coughing – exacerbated by exercise or restraint
g.Auscultation shows increased bronchial and tracheal sounds, esp in cranioventral lungs
h.R. equi foals may show nonseptic synovitis, D+ and uveitis
Rhodococcus equi
8-10 weeks old, when passive immunity declines
Two clinical forms of Rhodococcus equi
a.Subacute – diffuse miliary pyogranulomatous pneumonia, usually die w/in days
b.Chronic – pneumonia, compromised resp fxn and untrhiftiness
Inflammation of the pleural surface w/ exudation into the pleural space
Horses are ...more prone or less prone... to pleural fluid accumulation b/c arterial supply to pleura is from sytemic circulation (not pulmonary circulation)
more prone
In the horse (not other spp), it is...
secondary to pneumonia or pulmonary abscesses
Pleuritis/pleuropneumonia MC secondary to...
most common Pleuritis/pleuropneumonia in horses recently transported
Clinical signs with Pleuritis/pleuropneumonia
·Clinical signs
a.Fever, ADR
b.Nasal discharge – mucopurulent to serohemorrhagic
c.May see halitosis, wt loss and edema and pleural pain
d.Dyspnea, Tachypnea
e.O may complain of low grade colic or laminitis signs
f.Auscultation – can hear all but bronchial sounds
best prognostic indicator for Pleuritis/pleuropneumonia
ODOR – , can detect putrid smell (anaerobic bactreial infection)
Dx of Pleuritis/pleuropneumonia
Thoracocentresis for cell cont, cytology, protein, Gram stain, bacterial culture and senstivity, aneaerobic bacterial culture and mycoplasmal isolation
Tx of Pleuritis/pleuropneumonia
antimicrobial therapy and drains
Etiology of Tuberculosis in horses
Mycobacterium avium, bovis or tuberculosis
how is tb in horses spread?
Ingestion and inhalation, hematogenous spread causing acute miliary tuberculosis in lung or specific organ involvement w/ nodular lesions
Nutritional D+ in foals caused by
Caused by overfeeding milk or sudden intro of grain or roughage, or ingestion of sand, dirt or wood
Gastroduodenal ulcers in foals caused by
a. High grain diet or severe malnutrition
b. May be other causes including stress, NSAIDs, infectious agents
Clinical signs of Gastroduodenal ulcers
Clinical signs are bruxism (grinding teeth), ptyalism, low volume D+, colic and anorexia, lie in dorsal recumbancy
tx of Gastroduodenal ulcers
- H2 blockers (Cimetidine & Ranitidine)
- antacids (Aluminum hydroxide)
- Sucralfate
- proton pump inhibitor Omeprazole
- Prostaglandin E analog Misoprostel
- Metoclopromide – stimulate GI motility and enhance gastric empyting
- Bethanechol – cholinergic agonist
cause of septicemia in foals
Caused by bacteria through the blood stream from resp, GI, umbilicus, placenta or locatlized infection (jt ill, navel ill, pneumonia, encephalitis)
MC cause of septicemia in foals
E. coli
Clincial signs with septicemia in foals
a.ADR – depression, lethargy
b.Petechial and echymotic hemorrhaging in MM and ears
c.Shock or coma
d.Pneumonia, D+, ecepthalitis, uveitis, septic arthritis
e.Owner will think mare stepped on her foal
f.Neutropenia most often with toxic changes
Dx of septicemia in foals
IgG of < 800
Tx of septicemia in foals
colostrum IV if less than 12 hours old, Ab therapy
Parturition problems in the mare Number one cause is
presentation problem
Causes of prolonged gestation are:
a. Draft breeds
b. Mule crosses
c. Fescue
sequela of dystocia in a mare
a. Laminitis
b. Retained placenta
c. Metritis
fatal problem in older mares
ruptured middle uterine artery
low calcium
indications for induction on partuition in the mare
a.Owner conventince
b.Prolonged gestation
c.Urterine atony
d.Periparturent colic
e.Impending prepubic tendon rupture
f.Problem mare (steps on foal)
g.Preparturent leakage of colostrum
h.Nurse mare – used for colostrum only
guidelines for induction of partuition in the mare
a.Foal is in correct PPP
b.Gestation over 320 days
c.Full mammary development
d.Cevix is dilated at least 3-4 findgers
e.DO NOT induce if the mare has a systemic dz, there is a foul smelling discharge, or will have an abortion
DOC for induction of partuition in the mare
watch for this during partuition in the mare
‘red bag’ or premature placental separation
Moldy sweet clover – contains
dicurmarol which inhibits blood clotting
botulism occurs with
large round bales and ensilted forage w/ inadequate storage
tall fescue toxicity
N. coenophialum causes prolonged gestation, thickened placenta, abortion and agalacia
red clover toxin and CS
slaframine, slobbering (black spots on leaves and stems)
blister beetle toxin and CS
cantharidine, contaminate of alfalfa hay; causes D+, colic and synchronous diaphragmatic flutter
problem with Corn grain mold: Fusarium moniliforma
Corn and CSM
aflotoxins w/ Aspergillus

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