Large Animal Sx- Lameness Diagnosis 2

untimely's version from 2015-09-19 23:45

Diagnostic Anesthesia (blocks)

Question Answer
three types of diagnostic anesthesia?Perineural anesthesia (regional), Local anesthesia, Intrasynovial anesthesia
SAFETY is the primary goal. what are some ways you should control the environment?NO OBSTACLES, NO DISTRACTIONS, NO ESCAPE, NO OTHER HORSES MOVING NEARBY
who should restrain a horse with diagnostic anesthesia?a skilled assistant- NOT THE OWNER!
It is important to Communicate your actions to the restrainer. How do you let them know what you're doing when you're going to perform the block?Count 1,2,3 and stick. (Restrainer diverts attention of horse on count of 2)
do you stand on same or opposite side of the horse from the restrainer? Why?Stand on the same side as restrainer- This gives the horse an escape route without forcing the horse to trample over someone
how should you hold yourself when you are going to perform a block?do NOT kneel on the ground, Keep your head as high as possible, Pick the limb to be blocked up whenever possible
what are some tools you can use to physically restrain the horse for the block?Nose twitch, Skin twitch, Ear twist, War bridle. However, it is Some horses behave better without any form of restraint besides halter and lead rope
If you wish to restrain a horse with sedation, what should you keep in mind about the effects of these drugs?Many common sedatives are also analgesics and administration may reduce degree of lameness (but Small amount of xylazine will not eliminate obvious lameness)
Xylazine 100 mg IV (vs) Xylazine 250-400 mg IV. you'd use each amount for....100mg: Calm nervous horse. 250-400mg: For fractious horses
If you need to, how can you reverse the effects of the xylazine?Can reverse with tolazoline at 4 mg/kg IV
aside from xylazine what other sedative can you use in horses?Acepromazine 10 mg
****looking at a horse's leg from dorsal to palmar, what is the order of the bundle of vessels and nerves?VAN- vein, artery, nerve.
what gauge needle do you want to use for a block?small needle- 22-25G
how do you go about doing the actual injection for the block?use a rapid motion to pop the needle through the skin (on the count of 3 for your restrainer to be ready) and THEN attach the syringe to the needle (so if horse pulls away the needle and syringe don't wiggle around and cut the inside structures)
what are some complications of nerve blocks?Broken needles, Infection, Hemorrhage, Local edema, Makes primary condition worse, Inadvertent penetration of a joint or tendon sheath, Failure to enter joint, Hemarthrosis, Broken needles, Makes primary problem worse, **SEPSIS
how might a nerve block make a primary problem WORSE? (ie what major caution is there about using diagnostic nerve blocks)think twice about blocking an acute onset lameness- that is possibly a fracture. If the fracture is incomplete or non-displaced, you have a chance of de-stabalizing it by numbing the supportive soft tissue structures in that area
how common is post-injection sepsis?22% of joint infections in horses are caused by joint injection
Sources of infecting bacteria which can cause post-injection sepsis?Skin of the horse (lots of bact on it), Surgeon (many vets are positive for MRSA), Contaminated medication or equipment (multidose vials, Reuse of syringes or needles)
what is MRSA?methicillin resistant staph aureus
what is the most likely culprit for a joint sepsis? (causative agent)prolly staph
do you need to shave the injection site?Presence of hair does not inhibit ability of antiseptics to “effectively” reduce bacterial flora to an acceptable level
which is usually better- chlorhex or iodine solutions?Chlorhexidine scrubs are superior to iodophors for reducing infections
what's the Perdue skin prep for joint block regimen?Use chlorhexidine in 2 phase scrub- (1) Rough prep with non-sterile gloves (2) Final prep with sterile gloves and sterile gauze sponges. Finally, Rinse with sterile saline or alcohol (Alcohol decreases residual effect, Alcohol is good disinfectant)
can skin be sterilized?NO! Bacteria can be cultured from scalpel blades following surgical preparation
what are some problems associated with using needles to perform blocks?Most needles result in some coring of skin and/or transfer of hair into tissues :(
which needles are most likely to core hair?spinal needles (so remove hair if using 20G spinal needles)
when do you not need to remove hair when worried about hair coring?Hair removal not necessary for sharp cutting needles
how can you Clear needles of debris following insertion into joints?Allow synovial fluid to clear needle by dripping out or by aspiration
if you are concerned about contamination, do you want to insert the needle perpendicular to skin, or at an angle?Angled insertion Decreases OR for both tissue and hair by >60%
if you are concerned about contamination, would you prefer a 20 or a 22G needle?22G spinal needles Decreases OR for tissue and hair by >60% (or smaller- 20 seems too big)
Palmer digital nerve block--> what are the structures desensitized?Toe region of sole, Heel region of sole, Frog, Palmar 1/3 of foot, Navicular apparatus, DIP joint, PIP joint, Distal DDFT
*know all the things about which two blocks?Palmar digital block, abaxial sesamoid block
Technique for PD (palmar digital) Block--> what type of needle? how much anesthetic do you inject? 5/8 inch 25 g needle. 1.5-2 ml anesthetic
where do you insert the needle for the PD (palmar digital) nerve block?Insert needle just above ungular cartilage
what does the PD block look like?
what DOESNT the PD block desensatize?doesnt desensitize dorsal lamina
Diagnostic Analgesia in the Foot--> PD block--> diagram of what is blocked and where and why
Abaxial Sesamoid Block--> where do you inject for this block?Palmer/plantar nerves at level of base of the sesamoid bones (LOW NOT HIGH)
which block for subsolar abscesses?PD-- more specific than abaxial
which tissues does the abaxial sesamoid block effect?Sesamoid bones, Palmar fetlock joint, Distal and palmar part of proximal phalanx, PIP joint, Middle phalanx and soft tissues (including Distal sesamoidean ligaments), Entire foot
what type of needle do you use for an abaxial sesamoid block? and how much anesthetic do you use?5/8inch 25 gauge needle.... 3ml
do you direct needle distally or proximally for the blocks?distally
Palmar nerve block is aka?low volar
what does the abaxial sesamoid nerve block look like?

diagnositc imaging / Ancillary Tests for Lameness Evaluation / Treatment for Lameness

Question Answer
If you have a racehorse, do you wanna do imaging or blocks first?IMAGING FIRST- racehorses have high likelyhood of fx, you don't want to block with a fx (can make it worse)
what are the Diagnostic Imaging things you can do to a horse?Radiology, Ultrasonography, Thermography, Nuclear imaging, Computer Tomography, Magnetic Resonance Imaging
what is the one imaging thing that tells you WHERE something is but not WHAT it is?Nuclear Imaging (everything else tells us what but not where)
explain Nuclear Imaging a littleRadiopharmaceutical - Technetium 99m labeled phosphonates, which Bind to hydroxyapatite crystals, which means Concentrates rapidly at the site of increased bone metabolism. Then, Gamma rays emitted by Technetium 99m are counted with highly sensitive gamma cameras
downside to MRI?takes FOREVER to get image
when do you use Synovial fluid analysis?usually only if you suspect septic joints
if you want to dx with a treadmill, what should you keep in mind?can only go straight-- if lame when turning, not very helpful
list off some Ancillary Tests for Lameness EvaluationSynovial fluid analysis, Arthroscopy, Treadmill examination, Diagnostic acupuncture, Force Plates, Kinematics (Video analysis), Lameness Locator
if you see Hemarthrosis, what are you thinking?probably intraarticular fracture- do NOT block and then jog the horse
#1 treatment to consider for lameness?rest/retire
examples of Alternative therapies you can use for tx of lameness?Acupuncture, laser, homeopathy, chiropractic, massage
examples of Regenerative Therapy you can use to help tx lameness? Stem Cells, PRP (platelet rich plasma), IRAP(interleukin receptor antagonist protein), Bone marrow

Know ya joints

Question Answer
label the damn carpus
label the damn tarsus TA = Tarsus. CA = Calcaneus. CE = Central. i, ii, iii, iv = Other tarsal bones. Ti = Tibia. Fib = Fibula
which joints communicate in the hock?proximal two in the back- tarsocrural w/ proximal intertarsal
which joints communicate in the carpus?carpus is distal two: carpometacarpal w/ intermediate carpal
which synovial sacs communicate in the stifle?synovial sacks for the stifle are femoral-patellar w/ the medial femoral-tibial
what are the joints of the tarsus?
what are the joints of the carpus?antebrachiocarpal, middle carpal, carpometacarpal

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