Blog Archives

Splitting Prascend tablets

11/25/2013

The ECIR group recommends slowly increasing the dose of pergolide when introducing it, ideally in 0.25 mg increments - see www.ecirhorse.org - Pergolide.

And the Equine Endocrinology Group now also recommends introducing Prascend gradually:
"Some horses show a transient reduction in appetite. It is therefore recommended that PRASCEND be introduced gradually by giving partial doses for the first four days or by administering half the dose morning and evening."

Prascend comes in 1 mg tablets scored in half for easy division into 0.5 mg doses. If you need to divide tablets into 4 (for small ponies or for tapering the dose in 0.25 mg increments), talk to your vet to discuss options. It is important that tablets are split accurately, and vets sometimes suggest using a pill cutter/splitter.

Other suggestions for dividing Prascend tablets may not be safe or effective - always ask your vet and check the datasheet - NOAH Compendium - Prascend.

Half of a 1 mg Prascend tablet

The following suggestions for administering 0.25 mg Prascend (as seen on the internet) are not recommended:

Dissolving 0.5 mg tablet in a small quantity of water and giving half one day and the remaining half the next day - the datasheet states that if dissolving the tablet in liquid, the whole amount should be administered immediately.

Giving 0.5 mg every other day - the datasheet states that Prascend should be given once daily. As the average half life of pergolide has been found to be around 6 hours in horses (Abra Wright Pharmacokinetics of pergolide in normal mares, MSc thesis 2009), extending the time between doses seems counter-intuitive.

Cutting 0.5 mg half tablets into two with a knife - cutting the pills with a knife risks crushing/wasting some of the tablet (the datasheet states that tablets should not be crushed), as well as operator injury (and many horses seem to hate the taste of blood)!

Keep your fingers safe and your horse's medication effective - if you have to divide tablets, use a pill splitter.

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Measuring Collateral Grooves

11/6/2013

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What are collateral grooves and why measure them?

From Pete Ramey - Understanding the horse's sole:
"The seams between the sole and frog; the collateral grooves, are the most reliable and important guide we have for determining the needs of the foot. A full understanding of their significance and the information they offer will give you “x-ray vision” when you look at every hoof."

The pedal/coffin bone (P3) is dome-shaped on the bottom and covered with a 2-6 mm corium containing blood vessels and nerves. The sole covers this and provides protection - simply put, the thicker the sole, the more protection. So it is important to be able to estimate sole thickness.

In his book "Care and Rehabilitation of the Equine Foot", p 286, Pete Ramey suggests that the bottom of the collateral groove is fairly consistently around 10 mm (of sole) from the solar corium, so the collateral grooves can give an indication of the position of P3. In the few cases where we have been able to measure collateral groove depths and have x-rays taken, we have found the collateral groove measurements have given a good indication of the palmar angle of P3 - more on this another day!

How to measure collateral groove depths

Use something hard, flat and even, like a rasp or metal ruler, to lay across the top of the hoof from side to side, and a measuring stick or hoofpick to measure the depth from the bottom of the collateral groove to the flat object.

The collateral groove depth should be measured from the bottom of the collateral groove to the junction of the sole with the wall. So if you have wall height above the sole, you will need to take this wall height off the measured depth, to calculate the true depth.

The Precision Hoof Pick website has a good explanation of how to measure collateral groove depths with photos, and the Precision Hoof Pick is an excellent tool for taking accurate measurements.

You can make a collateral groove depth measuring stick very easily with a lolly stick, some coloured pens and a ruler - the stick below is coloured in 0.5 cm increments, the same on both sides.
Update: TLS now prefers to use something narrower to really get down into the collateral groove - such as a wooden kebab stick.

The Hoof Evaluator, although a bit expensive, looks very useful for measuring collateral groove depths and other measurements on the foot.

Another suggestion is to use a clench:
Alternative Uses of a Horseshoe Nail by Christoph Schork - EasyCare Inc

Measure the collateral grooves at the deepest part, which is normally towards the back of the foot, in line with the bars (deepest part/bars), and at the apex/tip of the frog (apex). Measure both sides of the frog - this tells you whether the foot is balanced from side to side.

The Precision Hoof Pick - cms marked along both arms of the pick, inches on the other side.

How deep should the collateral grooves be?

Pete Ramey suggests that collateral groove depth should normally be:
10 - 20 mm at the apex of the frog
15 - 30 mm at the deepest part towards the rear of the frog/beside the bars.

These are some of the ways TLS rehabs have recorded their collateral groove depths:

If you have less than 8 - 10 mm collateral groove depth, always use boots with thick pads or keep the horse on deep soft conforming bedding to protect the sole until the sole has thickened.

When trimming, always keep the rasp 15 mm above the bottom of the collateral grooves - this may mean floating the rasp in the air. For an excellent demonstration of floating the rasp above the toe, watch Linda Cowles' ml Trim4 video (from around 3.30 minutes in).

How collateral groove depths can be used to guide the trim

What if the collateral groove depths do not fall into the "ideal" 10-20 mm at the apex, 15-30 mm at the bars, the depth at the apex is less than the depth at the bars, or the measurements are not the same on both sides of the frog?

1. CG depth at the apex is greater than CG depth at the bars (so the "deepest part" isn't the deepest part!).
This could indicate a negative palmar angle, that the heel is too low, or that there is too much sole depth in front of the frog. Reassess the trim and if necessary have x-rays taken. See What to Know About Trimming the Toe... by Maria Siebrand - EasyCare Inc.

2. CG depth at the deepest part/bars is much greater than CG depth at the apex.
If the depth at the deepest part is much more than the depth at the apex (in our experience, usually more than around 1 cm difference), this could indicate too large a palmar angle, or rotation due to laminitis. Again, reassess the trim and if necessary have x-rays taken.

3. CG depth is not the same on both sides of the frog.
If the CG depth (this will usually be the deepest part/bars measurment) on one side of the frog is different to the CG depth at the same point on the other side of the frog, this could indicate medial-lateral imbalance. Again, reassess the trim and if necessary have x-rays taken (DP x-rays may be required). See All About Heels by Christoph Schork and Balanced Horse, Balanced Hoof - EasyCare Inc.

In some feet the collateral grooves cannot be easily identified at the front of the foot, because the frog has migrated forward into the sole. Reassess trim. See Live Sole and Then Some by Christoph Schork - EasyCare Inc.

The science

Researchers at Auburn University looked at the relationship between the external characteristics of the collateral grooves of the hoof capsule and the internal hoof structure on dissected feet. They noted that the collateral grooves appear to run parallel to and a fixed distance from the solar surface of P3 in the front (dorsal) half of the foot, and the same distance from the base of the lateral cartilages in the back (palmar) half of the foot, and that the orientation of the collateral groove in the front half of the foot parallels the palmar angle of P3. Based on Pete Ramey's findings, they suggested that in a healthy foot with adequate sole depth, the collateral groove depth at the frog apex should be around 10-20 mm from the ground.

They measured 96 feet and compared the measurements to lateral x-rays, and found that the depth of the collateral groove at the frog apex was highly associated with sole depth, distance of P3 from the ground, and palmar angle, as measured on the x-rays.

Rouben CM, Taylor DR, Degraves FJ, Schumacher J, Guidry LN
Evaluation of the shape and depth of the collateral groove of the foot as a method to predict the position of the distal phalanx within the hoof capsule
Phi Zeta Research Day Forum 2012 p 34

References and more information

Important - please read Pete Ramey's article Understanding the Horse's Sole thoroughly before you start using collateral groove depths to guide trimming, and/or chapter 16 Evaluating and Trimming the Sole in Care and Rehabilitation of the Equine Foot.
And ideally also One Foot For All Seasons? by Pete Ramey

See also:
Measuring Uniform, Adequate Sole Depth Using the Collateral Grooves - The Thoughtful Horseman

Collateral Groove Depth and Sole Concavity - Precision Hoof Pick

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General Laminitis Quiz

11/3/2013

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Here are the answers for TLS' first quiz - the General Laminitis Quiz - correct answers in bold:

Q1. Which is the most common "type" of laminitis
Endocrine laminitis - 61% got this correct
Supporting limb laminitis
Systemic Inflammatory Response Syndrome (SIRS) laminitis

Explanation:
www.thelaminitissite.org/laminitis
"It is currently thought that around 90% of cases of laminitis have an endocrine cause (Karikoski et al. 2011) , either Equine Metabolic Syndrome or Pituitary Pars Intermedia Dysfunction/Cushing’s,
and that pasture associated laminitis is an endocrine disorder in which horses (particularly ponies) have an abnormal insulin response to the sugars in grass."

Q2. A good daily check that can help early identification of laminitis?
Walking on hard ground/turning a tight circle - 72% got this correct
Checking body temperature/respiration rate
Walking a 20 m circle each way
Asking the horse to back up

Explanation:
www.thelaminitissite.org/laminitis
"Symptoms of laminitis include:
Feeling “footy” - preference for soft ground
Reluctance to turn"

"Daily checks that can help early identification of laminitis:

Walk on hard ground e.g. concrete - does the stride shorten, does he/she seem at all "pottery"?
Turn in a tight circle - normal or reluctant to turn/stiff behind?
Digital pulses - normal?
Regional fat pads - cresty neck, bulges in hollows above eyes, enlarged sheath, fat above tail? Hardening of neck crest or increase in any of these fat deposits can indicate imminent laminitis."

Q3. Which blood tests are recommended if a horse has a history of laminitis?
Insulin, ACTH, glucose - 65% got this correct
Glucose, cortisol, ACTH
Insulin, cortisol, TRH
Glucose, TRH, ACTH

Explanation:
www.thelaminitissite.org/laminitis
Management of laminitis:
"Diagnose the cause – test blood for insulin & glucose EMS plus ACTH for PPID"

Insulin provides information about hyperinsulinaemia/insulin resistance, which diagnoses EMS and indicates laminitis risk.
ACTH diagnoses PPID.
Glucose, although not essential, can add information - glucose can be raised in horses with PPID and in diabetes, which is very rare in horses.
Cortisol used to be considered diagnostic for PPID, but that has since been disproven.
TRH itself isn't tested, but the TRH stimulation of ACTH may be used to diagnose PPID - in which case it is ACTH that is tested.

Q4. Correct emergency treatment for laminitis?
Call vet, remove from grass, support feet if necessary, confine on deep supportive bedding - 93% got this correct
Call vet, allow access to grass, remove water, encourage to walk
Call vet, remove from grass, remove water, confine on bare concrete floor
Leave in field, give antibiotics and pain killers, encourage to walk

Explanation:
www.thelaminitissite.org/laminitis
"Emergency treatment for laminitis

call vet (and farrier/trimmer)
remove horse from grass (but move as little as possible/support feet before moving)
confine on deep supportive bedding e.g. sand, sawdust, pea gravel
support the feet if the bedding isn’t sufficient to do this, e.g. with styrofoam, impression material, boots and pads
give NSAIDs e.g. Bute, Danilon, Equioxx for the inflammation & pain (for as short a time as possible)
apply cold therapy to the feet to reduce inflammation and pain (but not if cold-induced laminitis/feet cold)"

Never encourage a horse with active laminitis to walk. There is no reason to remove water - laminitic horses should always have access to water. Antibiotics have no place in laminitis treatment, unless a bacterial infection is causing the primary illness leading to SIRS laminitis.

Q5. The Laminitis Site's philosophy for treating laminitis?
Identify and remove/treat the cause, support and realign the feet - 93% got this correct
Give the pills, raise the heels
Find the cause, shoe the horse
Support and realign the feet and the cause of the laminitis will disappear

No explanation needed here - TLS believes that if you identify and remove/treat the cause and support and realign the feet, you'll sort out most cases of laminitis - great that so many people got this one right!
www.thelaminitissite.org/

Q6. What is the maximum NSC % generally recommended when feeding a laminitic?
10% - 66% got this correct
5%
20%
25%

Explanation:
www.thelaminitissite.org/laminitis
Management of laminitis
"Feed low NSC (<10%) diet based on grass hay (+ protein, minerals, vitamins, linseed?) -do not starve"
The idea of 10% seems to have come from the ACVIM consensus statement on EMS - see under Dietary Management.

Q7. Which statement is true?
All/any feet can be affected by laminitis - 95% got this correct
Only the front feet are affected by laminitis
A single foot can't be affected by laminitis
Laminitis in all 4 feet is very rare

Explanation:
Nearly everyone knew that laminitis can affect all/any feet. Endocrine and SIRS laminitis are systemic, they affect the whole body, therefore all 4 feet have a chance of developing laminitis - more details here:
Can a horse get laminitis in any foot? - TLS forum

Q8. Signs of previous laminitis episodes in the feet include:
Hoof rings wider at the heel, stretched or deep white line - 83% got this correct
Hoof rings wider at the toe, tight white line

Explanation:
www.thelaminitissite.org/laminitis
"Symptoms of chronic laminitis:
Hoof rings wider at the heel
Stretched white line - deep black groove between wall and sole - laminar wedge"

Q9. What are the 3 components of EMS?
Obesity/regional adiposity, hyperinsulinaemia/IR, predisposition to laminitis - 56% got this correct
Diabetes, hyperglycaemia, predisposition to laminitis
Obesity/regional adiposity, hyperglycaemia, hirsutism
Diabetes, hyperinsulinaemia/IR, hirsutism

Explanation:
EMS was defined by the ACVIM consensus statement on EMS as including obesity/regional adiposity, IR or hyperinsulinaemia and a predisposition towards laminitis.
Diabetes is very rare in horses, and horses with EMS very rarely have above normal glucose (hyperglycaemia).
Hirsutism is diagnostic of PPID, not EMS.

Q10. PPID is initially thought to be caused by
The degeneration of dopamine-producing neurons that control hormone production in the pituitary gland - 54% got this correct
Excess cortisol production from the adrenal glands
A tumour in the pituitary gland
A tumour in the adrenal glands

Explanation:
www.thelaminitissite.org/ppid
"In a healthy horse, dopamine producing neurons from the hypothalamus release dopamine into the pars intermedia. The dopamine acts as a brake and stops hormone production.
With PPID the neurons are slowly lost (PPID is a neurodegenerative disease - it gets progressively worse) and the reduction in dopamine (there can be up to 9 times less dopamine in the pars intermedia of a horse with PPID than a healthy horse of the same age) causes:
the production of POMC peptide hormones (alpha-MSH, beta-endorphin, CLIP and ACTH) to increase - hormone levels may be more than 100 times greater than in a normal horse;"

It is now known that most horses with PPID don't have above normal cortisol production, and adrenal hyperplasia (increase in cells) and adrenal tumour formation is not commonly seen. Excess cortisol production is associated with Cushing's disease in humans and dogs - not horses, that's why the disease in horses is now called PPID.
Although a tumour or adenomas can develop in the pituitary gland, this is thought to be as a result of the loss of dopamine-producing neurons and the consequent increase in hormone production, so is not the initial cause. A difficult question that over half got right - well done!

Q11. Laminitis in the ................... is particularly suggestive of PPID
Autumn - 52% got this correct
Spring
Summer
Winter

Explanation:
www.thelaminitissite.org/s - see Seasonal Rise:
"Horses that are developing PPID often first present with unexplained autumn laminitis long before coat changes are seen, and any horse having unexplained laminitis for the first time in the autumn should be tested for PPID by testing ACTH". Sorry, should have said "Autumn/fall" to be international!

Q12. Cortisosteroids increase insulin levels - true or false?
True - 83% got this correct
False

Explanation:
Am J Vet Res. 2007 Jul;68(7):753-9. (PubMed)
Effects of dexamethasone on glucose dynamics and insulin sensitivity in healthy horses
Tiley HA, Geor RJ, McCutcheon LJ
"The study revealed marked insulin resistance in healthy horses after 21 days of dexamethasone administration. Because insulin resistance has been associated with a predisposition to laminitis, a glucocorticoid-induced decrease in insulin sensitivity may increase risk for development of laminitis in some horses and ponies."

And many more examples of corticosteroid causing increases in insulin levels and laminitis here:
http://www.thelaminitissite.org/d.html - under Dexamethasone Suppression Test
http://www.thelaminitissite.org/c.html - under Corticosteroids

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