Winter – The Joys of Living in the Great White North.

Although winter has given us a break up until now, chances are that this will change soon.  Horses are very well adapted to cold weather, and the feral horse population in the Northern hemisphere survives without blankets and snow pads.

Researchers found out that the Prezwalski horse “Equus ferus Prezwalski”, which is a very close relative to our modern horse  “Equus caballus” has, apart from a thick hair coat, the ability to down regulate its metabolic rate in order to conserve energy when food is scarce in winter. Despite that, during the extreme cold winter 2009/2010 in the Gobi Desert in Mongolia the re-introduced wild P-horse population crashed dramatically.

The wild horse population in North America is also well established and makes it through the harsh winters out West. While the population survives, the unlucky individual animals who are, for whatever reason weakened, will perish in the cycle of life and death according to the laws of natural selection and survival of the fittest.

We took care of natural selection by breeding performance horses that can jump, do fancy dressage moves, or race around barrels. I am not going to start a “to blanket or not to blanket” discussion, but the fact that we did take control of the breeding selection of our horses, means that we also have to take control of our horses’ comfort requirements (not only) during the cold season:

• shelter from wind chill,
• keeping horses dry, 
• meeting the horse’s energy requirements,
• water supply,
• and foot care.

Shelter Size  
According to the University of Minnesota, a general rule-of-thumb for run-in or open-front shed size is 240 square feet for 2 horses (i.e. 12 x 20 feet), and 60 square feet (i.e. an additional 10 x 6 feet) for each additional horse. These recommendations assume horses housed together get along well.

Keeping Them Dry  
These are the UoM suggestions and guidelines to blanket a horse if:

• There is no shelter available during turnout periods, and the temperatures drop below 5°F, or the wind chill is below 5°F.
• There is a chance the horse will become wet (not usually a problem with snow, but much more of a problem with rain, ice, and/or freezing rain).
• The horse has had its winter coat clipped.
• The horse is very young or very old.
• The horse has not been acclimated to the cold (i.e. recently relocated from a southern climate).
• The horse has a body condition score of 3 or less.

Proper blanket size and fit is important, in order to avoid rub marks or even injury. The proper type of blanket according to outside temperature is essential, a rain sheet alone has no insulating properties and can make it even worse, by compression of the insulating air-cushion formed the horse’s hair coat.

Feeding Requirements
The temperature below which a horse needs additional energy in order to maintain body warmth is called the lower critical temperature. This lower critical temperature in a horse with winter hair coat is about -7°C, for a clipped or horse with summer hair coat, it is about +7°C. The energy demand will increase about 1% per degree below that temperature.

In young horses their growth can be “put on hold” at low temperatures with a lack of nutritional energy.

Sometimes a thick hair coat can mask a poor body condition, especially in older ponies,

Water
Unfortunately, we see an increased number of impaction colics at this time of the year. Horses consuming winter feeds, have increased water requirements. Hay and grain normally contain less than 15% moisture, while in contrast, pastures possess 60 to 80% moisture. Even if quality feed is offered, horses will consume less if not drinking enough water. Fecal contents must maintain adequate moisture levels. If fecal material becomes too dry, intestinal blockage or impaction might develop. A horse will most likely not develop an impaction in one day, but can over several days to several weeks of inadequate water consumption.
The water in the waterers needs to be heated above freezing, adding one or two tablespoons of salt per adult horse is a good idea, as this will stimulate drinking.
Waterers should be cleaned regularly, and clean, fresh water needs to be always be available, regardless of temperature.
Foot care
Snow pads are absolutely necessary if your horses are shod and there is snow on the ground, as snow will otherwise ball up under the shoes and sole, creating a significant injury risk. If bare foot, please consider that frozen ground can lead to sole bruises and foot concussions.

Having said all this, let’s hope it is going to be a short one!

Prepurchase Exams

A waste of money or piece of mind?

Every done a home inspection? It starts with you sitting down with the home inspector on a table and signing several pages of waivers and exclusions. Then you hand over your cash or cheque and the inspector starts getting his tools ready. A flashlight a moisture-meter, a ladder…

It was my first time last year do witness- and pay for a home inspection and the most important thing I learned was If I have to sign 5 times minimum in order to acknowledge there can be hidden defects and damages in an innate object, that are not readily detectable to the trained professional, I probably should “upt” the paperwork of my prepurchase forms significantly.

So what do you get and expect from a prepurchase exam for the horse you picked?

This is what I sometimes hear when talking to the prospective buyer:

“ I just want to make sure he doesn’t go lame further down the road”- or “ I once had a horse with navicular-I need to make sure this one stays sound” – or “ we love him so much, he needs to stay healthy”

Do you feel the pressure??

This is what you can expect from a prepurchase exam – or vet check as it is also called.

I try to get a concise history from the owner about the horse in question, not only the medical history but its workload, feeding program, supplements and routine medications.

Then the exam starts with a clinical exam of the horse at rest, I try to get an overview of type, conformation and  temperament. The head, ears, mucus membranes (conjunctiva, nasal mucusa and gingiva) are assessed, next I listen to his heart, lung sounds and gut sounds. Check temperature? The simple process of taking the temperature  can be challenging in some horses – and by now I have already learned a lot about that horse, if nothing else then to be more careful around it.

The eyes are examined with a flashlight and a special tool called ophthalmoscope.

Opening the mouth, holding the tongue in order to assess the teeth can be another challenge for some of my patients.

After that the body and skin is checked for lumps, scabs, injuries and scars.

All four legs are lifted, the joints are examined for swelling and range of motion and the tendons and ligaments are palpated.

The feet are tested for pain and sensitivity with a simple but very useful tool  called “ hooftester” and the horn quality of hoof wall, sole and frog is assessed.

This brings me to another comparison with everyday buying and selling. Ever tried to sell a car with worn and flat tires for a lot of money??

No ? Well, I have seen quite a few sale-horses, no matter how high the price tag was, that would have desperately needed a good trim or shoeing job before the vetcheck.

Once the initial exam is done, we look at the horse in motion. Walking on straight line in walk and trot, lunging on hard and soft ground. And again here is the challenge, how do you trot a horse in hand that never learned how to do so? Or doesn’t know how to lunge.

Welcome to my world…

Next step: Every ageing’s vet favorite- the flexion tests. One leg after the other is held in flexed position for approximately a minute, then the horse is trotted off.

We do this in order to detect joint pain often related to wear and tear, but we have also keep in mind that especially older horses, that perform perfectly well in the show ring, might not flex that pretty sometimes.

Now it is time to get the heart rate up, with lunging in trot and canter while listening for respiratory noise (roar), I will again look for any lameness. After that I will auscultate the lung and heart again, in order to check for irregular heartbeat or abnormal lung sounds.

We are coming towards the end of the basic exam, some other tests, like backing up the horse, circling in a small circle and checking the tail tone are part of my neurologic assessment.

Then it is time to talk…

All the findings are considered confidential and it is completely up to the buyer-my client, to share that information with the seller or not. As there is neither the perfect vet, nor the perfect horse there is always something to talk about.

If the buyer is happy with the findings, we will proceed with x rays if requested.
There is no standardization in Northern America about which views and how many x rays to take in the pleasure and sport horse world. As it is quite often a money issue – the x rays can be by far the moist expensive part of a prepurchase exam – only a limited number of x rays are taken, I try to do that on a risk based assessment in these cases. For example in an ex- race horse I will have a close look at the knees (carpus), whereas if it is a warmblood I probably spend my clients money better on feet and navicular rads. Although I xrays are an important part when buying a horse, it is important to realize that even after imaging every possible joint, there is no guarantee for future soundness of the horse, it will however give you an important baseline about the joints and bones at the time of the exam.

Depending on the situation other tests or diagnostics might be done, endoscopy of the airways, ultrasound, blood work, specific tests for hereditary diseases and blood for a drug screen. Due to the fact that “bute”, “banamine” or other “painkillers” are readily available there is of course the risk that you get a horse presented that  has “bute on board….”

Needless to say that this is a nightmare for the exam and the interpretation of it.

My personal advice to clients is, if we take blood it should be tested immediately.

It is possible to take blood and freeze it, and to only have it analyzed if a problem arises a problem down the road, but I will advise that, while it might unveil a

“dirty deal”, at that point the chances of successfully using the results in court – should it go that far - are slim, due to what is  called “ a broken chain of custody”. The opposite lawyer will argue that the blood sent to the lab 4 weeks later could be anybody’s.

There is a wide variation of how pre-purchases are done between veterinarians and also between countries all with the same goal, to gather as much information about the horse in order to reduce the risk that is involved in buying a horse.

But like may other things in life –“ no risk – no Fun” and every horse owner will tell you that owning your own horse is one of the most rewarding things in life.

And finally here is an example of a disclaimer and while nobody is a fan of reading disclaimers, mine is a lot shorter than our home inspector’s….

Disclaimer:

It is important to remember that the pre-purchase examination can only give us information about the horse’s health and condition on the day of the exam. While this information is very important, it can never be a complete picture. Many factors that impact a horse’s health are not necessarily detectable on the day of the exam. The veterinarian cannot predict the horse’s future, and no guarantee can be issued.

Our role as veterinarian in the pre-purchase examination is not to “pass” or “fail” the horse. Instead, it is to help you make an informed decision by providing information about the horse’s health. Ultimately, the decision to purchase this animal can only be made by the prospective buyer. Remember, your veterinarian is happy to discuss any questions the prospective buyer may have about the exam findings.

OUR STRANGLES FACT SHEET

Ø Highly contagious bacterial infection caused by Streptococcus equi

Ø First FEVER > 3 to 14 days after exposure NASAL SHEDDING 2-3 days later for 2-3 weeks

Ø SYMPTOMS: swollen lymph nodes in throat area, nasal discharge, fever, swallowing difficulties,

Ø Other SIGNS: noisy breathing, respiratory distress, draining lymph nodes

Ø Transmitted by DIRECT contact with nasal discharge or secretion from draining lymph nodes

Ø OR contaminated buckets, tack, brushes, halters, PEOPLE or anything else that had direct contact with the sick horses DISCHARGE

Ø Treatment: ISOLATION of horses , hotpack, Banamine,

Ø Antibiotics only for certain cases

Ø STRANGLES is NOT an AIRBORNE disease!

What to do?

HYGIENE – HYGIENE – HYGIENE -  ONE HORSE –  ONE BUCKET – NO SHARING!

STOP MOVEMENT of HORSES to and from BARN

SEPARATE into 3 groups:

1.       Infected horses

2.       Horses that have been exposed or contacted infected horses

3.       Clean horses with no exposure

 ALWAYS handle clean horses first if possible. Assign a separate person for infected horses

WASH YOUR HANDS - SEPARATE CLEANING EQUIPMENT – TACK -  PASTURES

 First CLEANING and then DISINFECTION (BLEACH) of all used equipment – DAILY

Bacteria can survive up to several weeks (months) in the environment   (UV light kills Strept.)

Recovered horses may be potential SOURCES of INFECTION for at least 6 weeks

There may be asymptomatic carriers!

 For more info see: www.aaep.org/horseowner

Update on Equine Cushings - now called Equine PPID

Equine Cushing's disease was first described in 1932. Until recently it was considered to be caused by a benign tumor leading to pressure on certain parts of the brain and thus causing changes in the horse's hormone levels. 


Recent research has shown that Equine Cushing's is nothing like Cushing's disease (Hyperadrenocorticism) in humans and dogs, for example. Therefore the name  equine Cushing's disease should be avoided and has been replaced with PPID, which stands for Pituitary Pars Intermedia Dysfunction. It is the name of the part in the horses brain that is actually affected by the disease. We know now that it is NOT caused by a tumor, but  it is now actually considered a " neurodegenerative" disease. The formation and accumulation of misfolded "neuroproteins"  seems  to cause the dysfunction in the pars intermedia of the equine pituitary gland. Although there is no resemblance to true Cushings disease, we know now that this neurodegenerative disease has in some aspects more similarity with human Parkinson's disease.

While me measure ACTH in blood to test for PPID in horses, the cortisol levels in the blood are hardly ever elevated in affected horses, because the ACTH that is produced in abundance by the pituitary gland is not partially not hormonally active and cannot trigger increased cortisol production of the adrenal glands.

Looking at the connection between laminitis and PPID and it seems that the increase of  blood Insulin levels is the trigger or better the biggest risk factor for laminitis. PPID increases the risk for these horses with Hyperinsulinemia
For more formation about  Equine Metabolic Syndrome check out our first blogpost and the link to UoM.

You can find more information and a list of possible clinical signs of PPID here

For more  in depth information visit: the Equine Endocrinology Group website



ref: Pathophysiology and clinical features of pituitary pars intermedia dysfunction
D.Mc Farlane EVE 11/14

Understanding and Managing Equine Heaves/Recurrent Airway Obstruction (RAO)

Lisa Costa

January 2015

 Definition

Equine Heaves is a disease of the equine airways, which has been described as early as 333 B.C. (Morgan & Folch, 2011). It is characterized by a reversible narrowing of the airways via bronchoconstriction through inflammation as well as excessive secretion and accumulation of mucous. This results in a decrease of function of the pulmonary system during episodes of the disease (Morgan & Folch, 2011). The term “heaves” has previously been described and interchangeable with the term Chronic Obstructive Pulmonary Disease (COPD), however, recently the comparison between heaves and COPD has proven that they are not the same disease. Current and recent research is suggesting that heaves is more homologous to asthma than to COPD, as allergenic responses are characteristic when the horse is challenged by the etiological agents. From this switch of theory, heaves is now more acceptably termed Recurrent Airway Obstruction (RAO) (Robinson, 2001). 

Symptoms and Physiology

RAO has a wide range of symptoms and clinical signs, which are as follows (but are not limited to):

-          decrease in performance

-          exercise intolerance

-          cough

-          mucopurulent nasal discharge

-          mucous accumulation in peribranchiolar alveoli

-          mineralized mucous (branchiolar and/or alveolar plug)

-          bronchoconstriction

-          submucosal fibroplasia and fibrosis

-          smooth muscle hyperplasia

-          abnormal lung sounds

-          enlarged lung percussion field

-          abdominal effort

-          “heave line”

-          low blood PaO₂ values at rest   less than 95 mm Hg at sea level

-          high Alveolar-Arterial O₂ gradient immediately and persisting after exercise (more than           7mmhg) (Robinson, 2001)

These symptoms all are due to, or result in, an increase in airway resistance therefore causing an overall decrease in the respiratory system fuction. Due to this decrease, gas exchange between the alveoli (lungs) and the blood cannot occur at sufficient rates to sustain the actions of a horse, especially in exercising horses. From this, it is often seen that the horse will induce extra effort in is breathing, otherwise known as “heaving”. This creates a muscular build of the abdominal muscles involved in the extra exertion resulting in the well-known “heave line” (Morgan & Folch, 2011). RAO Horses that are allowed to reach a severe stage of the disease will become unable to partake in any form/level of exercise and may have to become candidates for euthanasia due to the welfare of their situation.

Etiology and Pathology

RAO is a subject under constant research, as the etiology is not completely defined and universally concluded on. In basic explanation, the airways are narrowed due to inflammation, constriction, and mucous accumulation due to hyper-reactiveness (Morgan & Folch, 2011). There is a range and variety of etiological agents causing this pathology, with the similarity among them being that they are airborne agents which is breathed in.  These agents are mainly found in your general “stable dust”, which is shown to be the cause of the majority of stabled horses presenting RAO (Robinson, 2001; Morgan & Folch, 2011). Summer-Pasture-Associated-Obstructive-Pulmonary-Disease (SPAOPD) is a form of heaves resulting from agents found in the outdoor pasture environment (Robinson, 2001).

Agents found to cause or relate to RAO and SPAOPD are as follows (but are not limited to):

-          moulds

-          endotoxins

-          dust mites, forage mites (and their feces)

-          fungal spores

-          thermophilic actinomycetes

-          organic dusts (β-D-glucans)

-          inorganic dusts

-          pollens

(Robinson, 2001; Morgan & Folch, 2011)

RAO has a similar pathogenesis to asthma, this being that it is understood as an allergic reaction to any of these airborne agents. The horse’s airway walls are hypersensitive to these agents. When these agents contact and bind to the various receptors found on the epithelial wall, a hypersensitive response is triggered initiating an allergic reaction. Through the mobilization of specific cells and signals (Th2 cells, mast cells, neutrophils, eosinophils, cytokines, etc.) inflammation, bronchoconstriction and mucous secretion occurs throughout the airways. This restricts the overall airflow into the lungs/pulmonary system as the horse’s body tries to prevent any more of the agent from entering its system. RAO is also characterized by the reversible nature of these processes once the horse is removed from the challenging environment and agents, allowing the horse relief from these symptoms (Robinson, 2001).

There is no current described relationship between the probability of a horse having heaves and its gender. However, there is evidence suggesting that the condition is heritable, with possible relationships among breeds and lines (Robinson, 2001; Gerber, et al.  2009).

Treatment    

                                              

Treatments are aimed at providing immediate relief of the constricted and inflamed airways as well as reducing the hyper-responsiveness, i.e. the allergic response, of the epithelial tissue in the airways. This is done through β₂-adrenergic suppressors and corticosteroids. The β₂-adrenergic suppressors act as a bronchodilator, suppressing the inflammation of the airways and providing immediate relief. This will reduce the bronchoconstriction and allow for mucociliary clearance. Daily administration of a corticosteroid is aimed at suppressing the hyper-responsiveness of the airways, to help prevent future allergic reactions to the allergenic agents. The best drug therapy shown to have the highest effect with no significant side effects for RAO is the use of aerosolized corticosteroids (Robinson, 2001). However, changing the management practices of the susceptible horses by diminishing the contact with the allergenic agents is critical in preventing the onset of RAO (Ivester & Couëtil, 2014).

Preventative

Along with the daily administration of corticosteroids to the RAO susceptible horse, it is important to try and remove the horse from environments or situations which put the horse in contact of the agents. This is very difficult considering is it commonly the housing conditions which are what presents the etiological agents (i.e. “stable dust”) to the horse. However, there are many easy practices to help diminish the amount of stable dust from coming in contact with your horse and its respiratory system. As well, the feeding management of your horses can result in the onset of RAO due to the various organic dusts, moulds, and mites that can be present in hay and grain (Ivester, et al. 2014).

“Stable Dust” Management:

-          cleaning/dusting/sweeping your stable regularly

-          only cleaning/dusting/sweeping your stable when horses are not present in the building

-          allowing sufficient time for airborne “stable dust” to settle after cleaning before bringing horses back into the environment

-          sprinkling water in your aisles using a watering can before sweeping to prevent airborne dust

Feeding Management:

-          soaking hay to suppress dust

-          steaming hay to suppress dust and fungal spores, kill molds and mites

-          wetting/soaking grain

-          feeding hay on a clean ground free of shavings, dirt and dust

-          not feeding hay out of a manger

o   A manger traps the dusts and fungal spores which accumulate in the air of the manger.

-          not feeding hay out of a hay rack or hay bag

o   By keeping a horse’s head high, is counteracts the natural feeding physiology of a horse. When a horse’s head is down, the neck and airways are aimed, encouraging more effective mucosal removal of captured agents. Also, the act of ripping hay out of a rack or bag will produce airborne dusts and fungal spores

Although a horse may not currently present indications that it is susceptible to RAO, it is important to be preventative towards the unaffected horses as well, as the disease often shows up later in a horse’s life (>5 years) (Leguillette, 2003). Partaking in these management changes may seem simple enough, and maybe even a bit redundant, however can be proven very effective. Most of the etiological agents that cause RAO are microscopic, and although you may not see a significant amount of dust in the air, there will still be microscopic agents airborne, putting the horse at risk (Ivester, et al. 2014). Of course, no practice can achieve perfect environmental status to completely protect a horse, but every small effort made will result in some aid, prevention, and relief of RAO.

References:

Gerber, V., Baleri, D., Klulowska-Rötzler, J., Swunburne, J. E., Dolf, G. (2009). Mixed inheritance of equine recurrent airway obstruction. Journal of Veterinary Internal Medicine/American College of Veterinary Internal Medicine. 23(3), 626-630

Ivester, K. M., Couëtil, L. L. (2014). Management of chronic airway inflammation in the horse: A systematic review. Equine Veterinary Education. 26(12), 647-656

Ivester, K. M., Couëtil, L. L., Zimmerman, N. J. (2014). Investigating the Link between Particulate Exposure and Airway Inflammation in the Horse. Journal of Veterinary Internal Medicine/American College of Veterinary Internal Medicine. 28(6), 1653-1665

Leguillette, R. (2003). Recurrent airway obstruction - heaves. Veterinary Clinics of North America - Equine Practice. 19(1), 63-68

Morgan G., Folch, H. (2011). Recurrent airway obstruction in horses - an allergic inflammation: a review. Veterinarni Medicina. 56 (1), 1-13

Robinson, N. E. (2001). International Workshop on Equine Chronic Airway Disease. Michigan State University 16-18 June 2000. Equine Veterinary Journal. 33(1), 5-19

Metabolic Syndrome - Insulin Resistance

Equine metabolic syndrome ca be a frustrating disease for horse owners and veterinarians. A group of researcher from the University of Minnesota has developed a very informative website about this syndrom: Equine Genetics and Genomics Laboratory
Currently they are investigating the role of genetics in EMS.

The University of Minnesota has also developed DNA tests for PSSM and is looking into the genetics of melanoma developement in grey horses.