Food Ani. Med- Bovine- Musculoskeletal Disorders (Lameness) 1

drraythe's version from 2016-04-29 15:28

so lame: intro and stuff

Question Answer
lameness is the #1 ___ issue on dairy farmsWELFARE
what is the Economic Impact of Lameness? (Dairy, Beef, & Sm. Ruminants)(!) Decreased production (meat & milk) (2) Decreased reproduction (Increased days open) (3) Culls are increased ( ~16% due to lameness / injury) (4) dec BCS
reminder of cow BCS (1-5)
reminder of cow BCS (1-9)
examples of various lameness scoring guides
explain what leg conformation is, what is normal, what are 2 possible abnormalitiesshould be straight down for the most part, shouldnt be cowhocked/splayfooted or bowlegged/pigeon toed
where does most lameness come from?90% of all lameness is in the foot (dairy-- beef is 75-80% which is still majority)
*Which feet are more commonly lame-- rear or front?REAR FOOT MORE COMMONLY
*If the front foot is lame, is the L or M claw more commonly affected?MEDIAL CLAW
*if the rear foot is lame, is the L or M claw more commonly affected?LATERAL CLAW
a sign of difficulty in rising with small rumis is...walking on carpi
for your hands on exam, do you work prox to distal or distal or prox? Work distal --> Proximal
anatomy review of foot
hoof growth is formed from what structure...what are the diff areas of the structure (pic)corium!
what are normal hoof dimensions (just a pic, not sure how important)3" dorsal wall, 5-7mm sole.
how does pressure distribution differ between normal and overgrown hoof?normal distributes over front half of sole. abnormal overgrowth puts pressure on heel
how does a camelid foot differ from a cow or small rumi?Two digits on each foot, Soft pad over corium and digital cushion--> nail is non-weight-bearing
these are the zones of soft tissue around the hoof. What tends to happen in zone 10? zone 0?0= between the claws= foot rot. 10=between heel bulbs= Hairy Heel Wart
SO if you needed to place a statistic bet, where is most lameness (specific area)90% in foot --> REAR foot--> LATERAL claw
why is lameness in the front limbs less common? Why is it more common in the rear? Lameness is less frequent in the front limbs due to cushioning provided by the soft tissue connection of the limb to the body, Unlike the hind limb which has a rigid connection to the skeleton.
*remember if the front foot is lame, its almost always the _________ claw, because--MEDIAL claw, bc it bears 80-90% of the weight of the limb
Nerve blocks are not commonly used in cattle (this is more a lameness check in horses) however 2 regional anesthesias commonly used when doing sx procedures for lameness in cattle are...(1) Bier block (2) ring block
what is a bier block? Ring block?Bier: Inject directly into vein. . Ring: Inject into tissues above area to be worked on.
If a ring block, do you inject a ring around the tissues above or below where you will be working on?above
explain regional limb perfusion--> bier block procedureTourniquet--> Place 19 ga. butterfly catheter with extension--> Inject slowly (20cc of 2% Lidocaine for bier block, typically for foot so midway between carpus and foot- could do this with abx too but its not a bier then lol) --> wait--> remove tourniquet.
(i think he said FYI) IVRA of the Digit--> 3 vessels in the front limb you can use?Dorsal metacarpal vein., Plantar metacarpal vein., Radial vein.
(i think he said FYI) IVRA of the Digit--> 2 vessels in the rear limb you can use?Cranial branch of lateral saphenous vein., Lateral plantar digital vein.
injection sites for IVRA? (what is the arrow in the pic pointing at)arrow is in his best opinion where to try to hit for this. Just above the medial sulcus of the claws.
IV Regional Analgesia of the Digit is best performed with the animal in what position? Best performed in an animal that has been cast (put into recumbency) but can be in a sedated or standing animal
if you need to perform IV regional analgesia of the digit in a smaller animal, how can you avoid toxicity from the lidocaine? In smaller animals, release tourniquet for short periods to avoid toxicity. Release tourniquet for ~10 seconds, then re-tighten for a few minutes & repeat.
what is the toxic dose of lidocaine according to him? Lidocaine toxicity ~6-10mg/kg (7 mg/kg).
Maximum duration for tourniquet application with IV regional analgesia?2 hours
(said in class, had a pic on the slide) how do you position the top and bottom leg when you have the animal in lateral recumb? and what's the reasoning for this?radial nerve can go over point of shoulder or elbow, which means it puts pressure on nerve when we tie them down. try to put pad under shoulder and pulling down leg FORWARD instead of BACK

Foot disorders: Interdigital Necrobacillosis (footrot), CHRONIC FOOT ROT/ SMALL RUMI foot rot

Question Answer
foot rot is an infectious dz which causes deep dermatitis of what part of the foot?INTERDIGITAL SPACE (0 on pic)
how common is foot rot, and which systems is it most common in? Leading cause of lameness in feedlots & confinement dairies. (Occasionally diagnosed in pasture cattle)
foot rot affects all ages, but is most commonly dx at what age/stages?most commonly Dx’d in mature or weaned cattle.
when first examining the cattle, where is the most likely place you are gonna see footrot first on the body? (medial dorsal cleft area-- can show up in rear cleft too)
what is the causative agent of footrot, and how does it infect the moo? Trauma to the interdigital space allows entry of Fusobacterium necrophorum.
what are some predisposing factors to footrot?Maceration of the skin of the interdigital space will predispose the animal to injury & infection. Rough surfaces, wet, & unsanitary conditions are important factors in infection.
what is the specific inflammatory problem F. necrophorum causes, and what is a virulence factor it has? F. necrophorum causes a suppurative Necrotic Cellulitis. F. necrophorum produces a leukocidal exotoxins --> Reduces phagocytosis
Secondary bacterial infections are common with foot rot. what is a common 2* agent and what is a virulence factor it has?Bacteroides produces proteases that damages connective tissue & tendons.
what are the clinical signs of foot rot?Painful lameness., Swelling & erythema of interdigital space. Fissure between claws is moist, red, and necrotic with a foul odor. Claws may be spread apart (from swelling), Sloughing of skin between claws. in SEVERE CASES, Swelling proximal to coronary band (possible joint infxn)
what are some appropriate antimicrobials for tx footrot?PPG (procaine penicillin G), oxytetracycline, Ceftiofur, Sulfonamides, among many others. Debride any dead tissues
If there is no response in 7d to treatment, consider/do what? Re-examine: May have spread to deeper structures – may need surgical debridement.
what are some ways you can help prevent foot rot?Prevent with clean environment, provide foot baths. There is a vx but it is of questionable efficacy
when footrot becomes very chronic, what happens to the limb?Septic Arthritis of Coffin Joint (+/- Pastern)
Lame cows with swelling proximal to coronary band should be examined for...septic arthritis
what is a useful thing for dx and px of chronic foot rot (septic arthritis of coffin and pastern)?radiographs!
what are you looking for dx/px-wise when radiographing a chronic footrot case? Osteomyelitis of P2, Osteitis of P3 & Navicular bone
what are your tx options for chronic foot rot/ septic arthritis? Anesthetize foot. Then Open infected joint, debride, --> Facilitated Alkalosis/Amputation
(explained in class with pictures) how do you go about amputation of a digit?use wire saw... want to angle it to hit the joint space. better to be too above it than too below it.
how do you perform facilitated ankylosis? what is very important that you do?Curette or drill away infected bone. to Get rid of the “hiding places” for bacteria, and Allow for drainage.. LOTS OF LAVAGING HE WROTE IT LIKE 7 TIMES
where do you aim if you wanna do facilitated ankylosis of the coffin joint?The coffin joint is located 1/3 the length from the coronary band to the sole and midway between the front and back of the hoof.
once you have drilled through the coffin joint for facilitated ankylosis, how do you do post-op management/ what do you do to the other claw?Hoof Block on opposite claw. Bandage/cast. Stall rest in clean, dry area. Antibiotics
(said in class) why do you use hoofblocks, what is a downside to them?Use to take pressure off of bad/affected claw, such as after you do a facilitated ankylosis on a chronic foot rot. However, can sometimes cause them to be lame with this bc now have all this pressure on the toe which isnt used to the pressure.... might have to take it off and try sthing else
What is the etiological agent of footrot in SHEEP? Primary agent of Infectious Footrot in sheep is Dichelobacter nodosus.
Cattle footrot agent vs sheep foot rot agent?CATTLE: fusobacterium necrophorum. SHEEP: dichelobacter nodosus
sheep may have inc susceptibility to footrot caused by dichelobacter nodosus if they are co-infected with?Susceptibility may be increased by infection with T. pyogenes.
how long does dichelobacter nodosus last in the environ?Bacteria survive a short time in the environment but for years in carrier sheep.
clinical signs of footrot in sheep?(dichelobacter nodosus) Lameness in one or more limbs (cattle is usu one limb) Numerous animals in the flock are affected. Inflammation & necrosis of interdigital tissue.
small rumi footrot--> what topical antimicrobial would you wanna use?Tetracycline
topical antiseptics (foot baths) can be used to help tx footrot...2 exs?Copper sulfate, Zinc sulfate

Papillomatous Digital Dermatitis (Hairy Heel Warts)

Question Answer
which population of cattle are most affected by PDD?Most commonly found in dairy cattle.
etiological agent of PDD?Thought to be caused by the spirochete Treponema.
what kind of conditions predispose to PDD? Usually found in herds with wet conditions. and Herds with recent additions to the herd
where is PDD most commonly found upon PE?bulb of heel or interdigital cleft. it is where interdigital cleft in the back is (10 on pic)
PDD/HHWs... compare what early versus late lesions look like(1) Early lesions: Sharply demarcated, Round to oval, Moist, strawberry-like (2) MAtURE lesions: Larger; up to 2 cm, Raised, Long, hair-like projections
you can use topical abx to tx HHW. What abx did he recommend, and what are two ways you can admin them?(1) Spray oxytetracycline on feet while in milking parlor. (Once daily for 5 d then repeat the next week; repeat in one month ) (2) Wrap foot with antibiotics (impractical in large herds with >5% prevalence)
what should you keep in mind about the effectivity of foot baths?too much organic material in them will inactivate them
what dimensions did he recommend for a medicated foot bath? What is the goal of these dimensions (as in what do they want covered)10 – 12 feet long, 4" deep. This is bc they want the whole foot up to the dewclaws submerged.
4 options for "health maintenance" foot bathsCopper sulfate, Zinc sulfate, Formalin, Tetracycline
Potential Footbath Problems (5)(!) Antibiotic Residues- like tetracycline/lincomycin. This might fall under ELDU. (2) Disposal of Formalin/Formaldehyde. (3) Effectiveness: Copper sulfate inactivated by organic matter. Hose feet off prior to entering bath. Tetracycline/Lincomycin have to be changed every 300 cows. (4) Ice in winter. (5) TOXICITY: Cows will ingest bath water (during hot spells, is there is no other water, if it is left standing)/ Acute copper toxicity (hemolysis).
main CS of acute copper toxicity (and when are we worried about ACT?)if they are drinking footbath water...see hemolysis