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Equine Medicine
Anatomy
Gastrointestinal
- Herbivore
- Teeth
- Dental formula I3 C1 PM3 M3 (42 M & 38F) I3 C1 PM3 M3
- Wolf teeth are vestigial upper first premolars
- Males usually have canine teeth (Tushes), while females do not.
- Dental rasping (Floating)
- floating teeth by filing down irregular enamel points to prevent malocclusion
- Started after 4 years of age after permanent teeth have erupted.
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Equine Medicine
Anatomy
Aging by teeth
Aging by wear and shape of incisors and Galvayne's Groove
- Measure wear or smoothness of the indentations (cups) in the incisors
- Cups disappear lower central, intermediate and corner at 6,7,8 years of age.
- Cups disappear upper central, intermediate, and corner at 9,10,11 years of age
- By 10 years of age Galvaynes groove appears at the gum line of the upper corner incisor
- Half way down by 15 years
- Completely down at 20 years
- Gone at 30 years
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Equine Medicine
Anatomy
- Horses do not have a gall bladder
- most digestion and fermentation occurs in the cecum
- Swine- spiral colon
- Ruminants (bovine, sheep, goats) - 4 chambered Stomach and rumen
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Equine Medicine
Bots (Gastorphilis sp)
- Asymptomatic conidition of equine and nonpathogenic
- Commonly found in stomach
- Rarely can cause neurological signs
- Fly larvae (bots) found in the stomach during winter months, from horses grooming their legs
- Where the flies leave their eggs
- Not treated, although usually destoyed with routine deworming with ivermectin
- Horse size is expressed in a term called Hands
- Hand is 4 inches
- Mearure from ground to withers
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Hoof anatomy
- Hoof encases P3
- Toe
- Heel
- Sole
- Bars
- Frog
- Quarters
- White Line
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Hoof Anatomy
- Splint Bones
- Second and fourth metacarpal and metatarsal bones
- Cannon Bone
- Third metacarpal bone
- Coffine bone
- Third Phalynx (P3)
- Navicular bone
- distal sesmoid bone
- Fetlock
- Metacarpalphalangeal and metatarsalphlangeal joint
- Pastern
- Long pastern- Phalynx 1
- Short pastern - Phalynx 2
- Auditory tube diverticulum (Guttural pouch)
- Between the cranium and pharynx
- Diseases as infectious, mycotic, abscess and tympany
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Horse medicine
Physical exam
- TPR
- General condition and environment
- Rectal
- Restraint by twitch, stocks or chemical
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Horse medicine
Procedures
- Oral meication
- Nasogastric tube intubation
- Orally mixed in food
- Injections
- IV- Jugular
- IM- neck or semimembranosus and semitendinosis
- Muscles of the hind leg
- Not to exceed 20 ml in one location
- Should not give injections in butt or gluteal region
- Intravenous catheters are placed in the jugular vein
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Horse medicine
Diseases
Colic
- Etiology
- Multifatorial disease identified as acute abdominal pain in horses.
- Dietary changes
- Foreign body
- Peritonitis
- Obstruction
- Neoplasia
- Hernia
- Enterolith- stone
- Sand
- Volvulus- intestinal twisting
- Parasites- Strongylus vulgaris (Strongyles)
- Uterine torsions
Enterolith can cause colic, they are made up of plant material and build up over time.
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Horse medicine
Disease
Equine Viral Enteritis
- Equine Viral arteritis- Effects reproduction
- Etiology
- RNA virus of Togavirus
- Transmission via respiratory tract and venereal
- Clinical Signs
- Pyrexia
- Ocular and nasal discharge
- Stomatitis
- Hindleg edema and stiffeness
- due to vasculitis
- Abortions
- Scrotal and mammary edema
- Petechiations and leukopenia
- Diagnosis
- Serology
- Virus isolation
- Nasopharyngeal or conjunctival swabs
- Clinical Signs
- Treatment
- Symptomatic
- Prevention
- Vaccination- MLV
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Horse medicine
Disease
Equine Viral Rhinopneumonitis
- Etiology
- Equine herpes virus (EVH-1)
- Associated with respiratory and neurological disease, abortions, neonatal disease
- Transmission is through inhalation
- Clinical Signs
- Rhinitis and pharyngitis
- Tracheobronchitis
- Abortions
- Foals with pneumonia
- Pyrexia and anorexia
- Neurological
- Ataxia and paresis
- Head tilt
- Lymphadenitis
- Lymphopenia and neutropenia
- Diagnosis
- Differential diagnosis
- Equine influenza
- EVA
- Strangles
- Virus isolation
- Histopathology
- Treatment
- Sypmtomatic
- Prevention
- Vaccination
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Horse medicine
Disease
Equine Influenza
- Etiology
- Orthomyxovirus
- Acute epidemic respiratory disease throughout the world
- Effects all horses, but primarily young unvaccinated horses
- Transmission through inhalation
- Clinical Signs
- Pyrexia and anorexia
- Ocular and nasal discharge
- URI- Upper Respiratory Infection
- Diagnosis
- Clinical signs
- Virus isolation
- Serology
- Treatment
- Symptomatic
- Prevention
- Vaccination
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Horse medicine
Disease
Equine Strangles
- Etiology
- Streptococcus equi
- Condition that results in upper airway obstruction due to enlargement of lymph nodes of the head and neck and future lymph node abscess
- Transmission is inhalation
- Effects young horses
- 100% infection in horses with no previous exposure
- Primarily causes abscess in submandibular lymph node and retropharyngeal lymph node.
- Clinical SignsPyrexia and anorexia
- Nasal discharge
- Respiratory stridor
- Dysphagia
- Facial and neck swelling to abscess
- Diagnosis
- Clinical Signs
- Culture
- TreatmentLance and drain abscess
- Fluids and nutritional support
- Antibiotics
- Penicillin
- Prevention
- Vaccination
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Horse medicine
Disease
Equine Infectious Anemia- No Vaccine
- Etiology
- Retrovirus from lentivirus family
- Trasmission through blood
- Blood to blood products as flies and tabanids
- Iatragenic from needles, surgical instrument
- Transplacental and colostrum
- Once horses are infected with EIA they become permanent carriers of disease
- Clinical Signs
- Pyrexia and anorexia
- Epistaxis- Bloody nose
- Anemia and thrombocytopenia
- Edema
- Death
- Diagnosis
- Blood profile
- Agar gel immunodiffussion test (coggins test)
- Elisa
- Prevention
- USDA accredited veterinarian must draw blood sample
- If positive on Coggins test entire herd is quarantined and state veterinarian onlu one that can lift quarantine
- Persistent carriers
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Horse medicine
Disease
Neonatal Isoerytholysis
- Etiology
- Mare develops antibodies to the foals erythrocytes
- After foal nurses colostrum antibodies a hemolytic anemia develops in the foal
- Clinical Signs
- Normal at birth, signs develop 8 hours to 4 days after birth
- Icterus
- Weakness
- Seizures
- Diagnosis
- Cross Match
- Foals RBC to mares serum
- Positive agglutination give a diagnosis
- Blood Panel
- Anemia
- PCV <20%
- Treatment
- Blood Transfusion
- Prevent foals from nursing off mare
- Prevention
- Blood typing mares
- Alloantigens Aa and Qa are responsible for most cases
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Horse medicine
Disease
Equine Encephalitis
- Etiology
- Togavirus
- Transmission by mosquitos
- Venezuelan Equine Encephalitis (VEE)
- Southeast, but primarily Mexico, Central and South America
- Eastern and Western Equine Encephalitis (EEE) and WEE)
- Temperate and desert climates
- Epidemic and zoonotic disease
- Clinical Signs
- Pyrexia and depression
- Stiffeness
- Ataxia
- Head Pressing, circling, head tilt
- Seizures
- Recumbent in 2-7 days
- Death
- Diagnosis
- Clinical Signs
- Serology
- Treatment
- Supportive
- Corticosteroids and antibiotics
- Recovery Rates
- EEE- 0.25%
- WEE- 50-80%
- VEE- 20-60%
- Many have permanent neurological damages
- Prevention
- Vector control
- Vaccination
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Horse medicine
Disease
West Nile Virus
- Introduction
- Fatal disease in horses, birds and man causing neurological disorderm seizures and fever and death.
- Caused by a Flaviviridae
- WNV transmitted through vectos as mosquito
- The virus is transmitted by bite of mosquito
that eners blood stream and migrates to the brain causing menigioencephalitis - Clincal Signs
- Range from asymptomatic, ataxia, stumbling, seizures and eventually to acute death.
- Horses do not usually hace fever
- Incubation 24 hours to 2 weeks
- Diagnosis
- Virus isolation and Elisa
- PCR
- Treatment
- None
- High mortality
- Prevention
- Vector control
- Vaccine - controversial
- Fort- Dodge killed vaccine
- Zoonosis
- Zoonotic disease transmitted by mosquitos
- Humans
- No clincal symptoms to flu like symptoms
- Fever, headache, back ache to severe signs as convulsions, disorientation and loss of consciousness
- No human vaccine or testing
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Horse medicine
Disease
Laminitis (Founders)
- Pathophysiology
- Laminitis is not an inflammatory condition of the foot, but a peripheral vascular disorder caused by systemic disease
- Which ultimately leads to laminar ischemia in the horses foot
- Which causes ventral rotation of the third phalynx and perforation of the sole of the hoof
- Etiology
- Grain overload (Excessive carbohydrate diet)
- Over exercise on hard surfaces
- Colic
- Obesity
- Cushings disease
- Systemic disease
- Endometritis
- Pneumonia
- Enteritis
- Clincal Signs
- Lameness
- Febrile
- Generalized stiffenss and warm feet
- Grain overload
- Bounding digital pulse and warm around hoof wall
- Sinker- depression dorsal margin of cornary band
- Exercise intolerance
- Diagnosis
- Hoof tester
- Pain over the sole and dorsal wall
- Radiographs
- Downward rotation of the third phalynx
- Treatment
- Remove initial cause
- Mineral oil- block toxins
- Remove from pasture- feed hay and water only
- Antibiotics
- Treatment with peripheral vasodialators
- Acepromazine
- NSAIDS
- Phenylbutazone
- Banamine
- KCL
- Nerve Blocks
- Heart bar and egg bar corrective shoes
- Takes pressure off the sole
- Prognosis
- Early Laminitis
- Good with medical treatment and diet control
- Guarded when
- Acute phase and pain more than 10 dayss
- Digital pain uncontrolled
- Third phalynx has rotated
- Poor
- Sinking of third Phalynx
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Horse medicine
Disease
Navicular Disease
distal sesamoid -navicular bone in the horse
- Chronic degenerative condition of the navicular bone that damages the flexor surface of the bone and the overlaying deep digital flexor tendon, navicular bursitis, and osteophyte production on the proximal lateral surfaces of the bone.
- It is a disease of the front feet that rarely effects ponies and donkeys
- Multifactorial disease with unknown exact cause and pathogenesis
- Pathogenises
- Vascular theory- arteriosclerosis and thrombosis lead to ischemia necrosis and bone resorption
- Biomechanical theory- pressure and vibrational forces result in degenerative changes to the navicular bone
- Eiology
- Typically effects older horses 7-12 years of age
- Larger performance horses as Warmbloods and thoroughbreds
- Uncommon in Arabs
- Exact cause in unknown
- Clinical Signs
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Lameness - Lameness appears worse on hard surfaces
- Horses may stumble and resist trotting in circles, and reluctant to jump
- Lameness worse on distal limb flexion test
- Heat, Pain, swelling are not usually present
- Hoof test is normal
- Diagnosis
- Radiographs
- Degenerative changes in the navicular bone with the change of the shape of the vascular channels from the normal triangle shape to inverted flask shape
- Clinical Signs
- Regional Nerve Blocks
- Must test positive for at least 2 of the 3
- Lameness disappears after nerve block or animal becomes sound is a positive result
- Palmar digital nerve block
- Distal interphalangeal joint
- Intrabursal at navicular bursa
- Treatment
- Hoof Care
- Roll the toe and raise the heel
- Egg bar shoes
- Medical (60%) successful)
- NSAIDS - Phenylbutazone
- Intra-articular and intrabursal injections
- of corticosteroids or Adequan
- Controls inflammation of the bursa and synovitis only
- Does not prevent or stop degenerative changes
- Surgery
- Desmotomy
- Suspensory ligament
- Neurectomy
- Palmar digital nerves
- Surgery is pallative it relieves pain, but is only 50% succcessful
- Lameness due to degenerative may return in 6 months to 2 years
- Prognosis
- May be sound for trail riding, but not performance
- Prognosis poor long term
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