Whinny, Author at Springhill Equine Veterinary Clinic

Breeding for dummies part 2….

Apr 15, 2012 | Breeding

I hope everyone had a great week and that you came out to say “Hi!” to the Springhill Equine folks at the Alachua Spring Festival. I know the staff and Doctors always look forward to the festival and its great vendors and activities. And continuing on our Spring theme, this week I am going to discuss the changes mares go through in Spring and Fall and during a normal cycle. These changes are very closely monitored by our Doctors by ultrasound to help them determine the best time to breed.

Last week I covered that horses are seasonal breeders during long daylight hours. Determining when that optimal amount of daylight happens to have our mares cycling is the tough part! To begin with our Doctors rectally palpate the ovaries and uterus. Normal ovaries are about half the size of a human fist, getting slightly small when the mare is out of heat and larger when in heat. During the winter the ovaries shrink down to the size of walnuts. The uterus on a normal cycling mare varies in tone during an estrous cycle (the period between ovulations). When your mare is in heat the uterus is very loose and floppy, when she is out of heat it is firm like a well toned muscle. If a mare is not yet cycling the uterus feels loose and floppy but the ovaries are small. So palpation is the first clue.

Next an ultrasound machine is used to look at the ovaries and uterus. Again our Doctors find that mares who are not cycling will have small ovaries with very small (less than 10mm) follicles and a uterus that feels like an in heat uterus but looks like an out of heat uterus (more on the difference later). If in doubt our Doctors will pull a progesterone level. A small amount of blood is taken and tested to determine if these levels are low, high or in the middle. Mares who are not cycling yet will be very, very low.

Now comes the tricky part….Before mares actually ovulate for the first time in a season they build a few big follicles which don’t ovulate, the uterus starts to have tone and everything looks like it is headed in the right direction only to stop just before ovulation occurs. This can mean several ultrasounds a few weeks apart to determine when your mare is finally ready for breeding!

Dr. Lacher and Dr. King have determined your mare is cycling and we can now work on breeding her. What the heck does that mean and what are they looking for to determine the perfect time to order semen or send her to the stallion? Three things have to happen for everything to be perfect: a follicle of 35-38mm in size, a uterus with a hint of edema, and an open cervix.

The ultrasound image below would be what Drs. Lacher and King would be looking for. They would measure across the black circles to determine when one reaches that magic 35-38mm.

Ovary

Uterus

They will also be looking at the uterus to see if there is any edema present. Edema is a very normal part of the cycle. The edema is seen in the image on the right and makes the uterus look like a wagon wheel or orange slice. Once at least a small amount of edema is present, a follicle of the correct size is seen, and the Doctors palpate an open cervix then an ovulatory timing drug such as deslorelin is given.

Drugs such as deslorelin help us precisely time ovulation. Once given 90% of mares will ovulate within a 36-48 hour window. This makes ordering semen from far away, making appointments with stallion owners, and timing of frozen semen insemination much easier.

Next week we will talk even more about the joys of the cycling mare and the fun of breeding! Until then may your litter box be clean and your food bowl full!

Horse Breeding for Dummies – Part 1. Seasonality

Apr 8, 2012 | Breeding

Let me tell you something – for a cat, Easter is heaven. There are all the usual joys of holiday snacking – cookies, delicious cakes, and other goodies flowing in from our wonderful clients. However, instead of having a cold winter day, surrounded by snowmen and the scary horned beasts in nativities, just think about Easter. Small, squeaky chicks, ducks and rabbits on a warm spring day, with many flowers to sniff and soft grass to roll in. And, of course, the always-popular Peeps in the microwave trick. I think it may be my favorite holiday.In celebration of spring (known to us in the Animal Kingdom as the season of the dreaded twitter-painting), I decided to begin a series on breeding your horse. It is a very complicated subject, and very different from what you know about people (or dogs or cats for that matter). In every discussion about equine reproduction, it is important to remember that all individuals are different, and so there can be (and usually are) exceptions to nearly every rule.Every species is unique when it comes to reproduction, and so I’ve learned that we classify many things about it – such if the species is ‘seasonal,’ or only breeds during one part of the year (horses are, cats and people aren’t!). If it is seasonal, when? Horses are considered seasonal breeders, and breed during the time of the year when the days are longest – eg. spring and summer. This is the opposite of say, sheep, who are seasonal but in the fall. Funnily enough, both end up having babies in the spring (as sheep are pregnant for about 5 months and horses are closer to 11). In Florida, we enjoy a prolonged breeding season due to our ample sunlight, so fall breedings and foalings are not uncommon.

Let’s talk more about seasonality. In winter, the mare generally is considered ‘seasonally anestrus.’ ‘Estrus’ (while many definitions exist) is the term scientists use to describe heat, or the period that the female is receptive to the male. In the horse, it is usually 3-7 days long, with an average of five days. ‘Anestrus’ is the term for when an animal does not experience heat cyclicity. This brings us to another classification for the horse – ‘polyestrus,’ or having multiple heat cycles in one season. All together, the horse is considered seasonally polyestrus (long-day breeder) with a period of winter anestrus. That was your check point – if you don’t understand that statement, please go back to the top of the blog.

Now let’s talk about the transition periods. Horses experience vernal (spring) and autumnal transitions – progressing from the anestrus period to the cyclic period, and back again. Spring transition is a matter of key concern for many people, most notably, the Thoroughbred racing industry. A Universal birth date of January 1^st is assumed for all Thoroughbred racehorses, and so the first baby born in the New Year is the oldest and the strongest in the pack. During these periods, the ovary is slowly adjusting to the new patterns. We will discuss more about ovarian activity and the corresponding changes in the uterus during our next blog, as we will about the specific changes that occur during the transitional periods. As always, thanks for reading! May your litter box ever be clean, and your food bowl full!

Heaves – What’s happening in your horse’s airways

Apr 1, 2012 | Ailments, Feed

From my counter, I watch Florida horse owners grapple with a number of issues that are particularly difficult to manage in our climate – from gnats to fungal infections, and of course the non-sweaters. Among these, there is one disease in particular that gets Florida horses (and their owners) down – heaves. I hear so much about it, that this week I stole Dr. King’s Naughty Pony article that explains heaves, inside and out!

Heaves, formally known as Recurrent Airway Obstruction (RAO), is an allergic respiratory disease similar to asthma in humans. Like with asthma, the primary symptom is that of respiratory distress. The high load of plant and mold allergens, exacerbated by the intense heat, makes life especially tough for a ‘heavey’ horse living in Florida. Heaves was first recognized as being associated with horses that were stabled in dusty barns and fed hay. The organic dusts associated with bedding and hay – containing molds, allergens, endotoxins, and small particulates, initiate the inflammatory cycle in the airways. In Florida, plant allergens alone can get your horse heavey – symptoms are usually worse in the fall for this reason (although the summer heat doesn’t help either).

The first response is for the airways to constrict – termed bronchospasm, which is the primary response with human asthma. The airways also produce mucus to try to trap the allergens, and move them back out of the airway. However, in the narrowed airways of the lungs, these mucus plugs lodge, closing off the path to the downstream air sacs (alveoli). As the horse attempts to move air into the alveoli, where oxygen can pass into the blood, the mucus plugs dislodge and re-lodge. This action is the root of the name Recurrent Airway Obstruction, changed from the old name COPD (chronic obstructive pulmonary disease). Over time, the muscle layer and fibrous scar tissue around the airways thicken, making the lungs less elastic, and less likely to recover. This means that the longer heaves goes unmanaged, the harder it will be to manage down the road. A recent study found that horses with RAO have a more intense response to the histamine control during Intradermal Skin Allergy Testing (ISAT), indicating that histamine is an important component of the allergic response with heaves.

Heave Line

Horses with heaves develop a characteristic appearance. The respiratory rate is increased (normally 12-24 breaths per minute), and the nostrils are wide open and flaring with each breath. The horse’s expression often appears anxious or distressed. With chronicity, the horse uses the abdominal muscles to try to move air, and a double breathing effort is seen in the flank. Over time, the horse develops a “heave line” just under the edge of the ribs from this motion (black arrow). Wheezing, first only heard with a stethoscope, becomes audible just by standing near the horse. The horse is losing weight by this point, and may extend the head and neck in its attempt to move air. Early signs may only be seen with exercise, particularly in dusty arenas. These include coughing, reduced exercise tolerance, and a delayed recovery from exercise (eg, respiratory rate does not return to normal in 5-10 minutes).

Diagnosis is generally straightforward, characteristic wheezing on expiration is heard with a stethoscope. A rebreathing exam (performed with a trash bag over the horse’s nose) and/or exercise may be required to bring these sounds out to an audible level. Definitive diagnosis is performed with a BAL (bronchoalveolar lavage), where a small amount of fluid is put into then recovered from the deep airways. The cells from the fluid are examined for the presence of inflammatory cells. Intradermal Allergy Testing, now offered by Springhill Equine, is an important diagnostic step to management and therapy of heaves.

Management of heaves is multi-factorial and challenging (that means there is no miracle shot). Housing is an important consideration – on pasture is usually preferable to stabled, however, it is important to know the source of the horse’s allergic response. For example, a horse who is allergic to dusts and molds should be managed differently from a horse allergic to trees and weeds – and this is where Intradermal Allergy Testing comes in (see story above). Another benefit of allergy testing is immunotherapy – an individualized prescription program developed based on the findings of your horse’s intradermal test. These tiny shots teach your horse’s immune system to hold its’ horses when responding to these everyday particles. Once we know what your horse is most allergic to, targeted avoidance also becomes easier. For example, you can walk your pasture knowing that it’s crucial to get up all the pigweed. Or, you can improve ventilation and soak your hay for 5-15 minutes prior to feeding to minimize molds and dusts. Other management techniques to reduce dusts include reduced sweeping (which stirs up dust), watering arenas, and removing roundbales. Rolled or processed grains should be replaced with soaked pellets. Alfalfa pellets and cubes, as well as whole grains, have lower amounts of dusts. However, consider your horse’s response to alfalfa during the allergy test – food allergies exist in horses too!

Finally, the mainstay of heaves management is steroid therapy. Whether using dexamethasone, prednisolone, or triamcinolone, our last desperate attempt to quiet the allergic response is to suppress the immune system with steroids. Side effects, which include worsening or inciting laminitis or infections, make steroid use less-than-ideal in many patients. However, they work much better than non-steroidal anti-inflammatories, like ‘bute’ (phenylbutazone) and ‘Banamine’ (Flunixin meglumine). We reach out to aerosolized steroids like Beclomethasone and Fluticasone in some cases – administered via a specialized horse mask. Attempts to manage heaves with other medications, such as antihistamines like hydroxyzine, have had variable success. Bronchodilators, like clenbuterol or albuterol, are generally only used as rescue medications for acute attacks, or prior to administering aerosol medications. However, the new evidence regarding the histamine response in ISAT indicates that antihistamine therapy may be worth reconsidering when managing the challenging heaves horse.

In summary, heaves (RAO) is a challenging and debilitating disorder to which horses in Florida are especially at risk. We hold renewed hope in managing it with the introduction of Intradermal Allergy Testing at Springhill Equine, allowing us to not only identify allergens to avoid, but also to provide an immunotherapy prescription for your horse.

Please contact Springhill Equine if you have any questions regarding management of heaves, or regarding allergy testing your horse! As always, may your litter box be clean and your food bowl full!

Horse Breeding for Dummies Part 5 – Management of Late pregnancy and Birth

Mar 15, 2012 | Breeding

Haylo! Thanks for dropping by for the next “Mare” chapter of our Repro edition blog! Last week we discussed confirmation of pregnancy, management of twins, and the ‘last ditch’ 25-30 day check. Now we are going to discuss the remainder of pregnancy and birth. There are many facets and approaches to pregnancy management – we are going to discuss what the Springhill doctors view is of ideal management.

Starting at breeding, you should be managing your mare in a variety of ways. She should be in a clean, comfortable space with companions who are not a source of stress. She should have ample access to plenty of high quality hay and clean water. Changing over to a higher protein (14%) grain is recommended (although Senior feed is always best for older mares), but please refer to my segment where I visited Dr. Lacher’s feed room! A mare’s demands change as the baby grows, as she can physically fit less fibrous feedstuffs, and has to rely more on concentrated grains.

We recommend starting pregnant mare vaccines at 3 months of pregnancy – particularly Pneumobort (Rhinopneumonitis). This vaccine is repeated at month 5, 7 and 9 of pregnancy. It helps to prevent abortions caused by specific strains of equine herpes virus (Rhinopneumonitis). Your mare should also receive her EWT vaccine every six months (starting prior to breeding), and should be boostered 4-6 weeks prior to foaling. Your mare should be vaccinated for Rabies and West Nile prior to breeding, and then again with the EWT vaccine 4-6 weeks prior to foaling. These vaccines will help boost her antibody levels just prior to producing the colostrum (first milk) that will supply the foal’s immune system for the first 4-6 months of life.

She should be checked regularly for any pus or other discharge from her vulva, which is sometimes seen underneath and/or in the tail. Discharge during pregnancy often indicates placentitis, an infection of the placenta that compromises the foal and the pregnancy. You should be monitoring your mare’s udder in late pregnancy for signs of development. Early development (5-9 months) can indicate placentitis as well. Please call if your mare exhibits these signs, so we can get your mare on antibiotics (often they use the free ones from Publix!)! If your mare does abort, please let us know and the vets can try to decipher the reason (eg, it could be one of two twins!)!

Ultrasounds can also give us information about the placenta and the foal. Dr. Lacher and Dr. King can attempt to determine if it is a boy or a girl between 59 and 65 days. We use ultrasound later in pregnancy (5-11 months) to determine the state of the placenta, the fluids surrounding the fetus, look for signs of infection (placentitis) – of which there are different forms and causes, and measure the heart rate of the baby. For example, we can measure the thickness of the placenta just in front of the cervix to see if it is thickened. This often indicates bacteria are ‘climbing in’ through a leaky valve – the cervix. This commonly occurs in mares that have had past foaling difficulty and damage to their cervix. If the foal’s heart rate is elevated, it indicates stress (like with placentitis), and if it is slowing down it may indicate impending death.

You should be monitoring your mare’s udder in late pregnancy for signs of development. First the udder begins to fill, but until the teats begin to fill and elongate the mare likely still has time. The first secretions will be a thin, watery drip, and over days to weeks it will change to a thick, sticky white milk. You can bring samples of milk to the clinic in a tube or cup (we can provide you) for us to test the relative concentrations of calcium and other ions, which gives us an idea of time until foaling. The closer she gets, the softer the muscles around her tailhead and the longer her vulva will appear. Remember that maiden mares can be much more unpredictable when it comes to pre-foaling development. When the incredible process finally begins, be ready for a few common issues.

A red bag is caused when placentitis makes the “bag” so thick the foal cannot break through. Once the umbilicus breaks, the foal has no source of oxygen. If a red velvety bag is protruding from your mare (Careful! The foal’s feet are behind it!), cut it with a knife ASAP! DON’T WAIT for us to get there! Call us as soon as you have cut the bag and have the foal’s nostrils clear of materials. Another birthing problem is dystocia (difficult birth), which occurs when the foal is malpostitioned, or sometimes with deformities. If your mare is actively foaling (following the water breaking) for more than 30 minutes, you should be calling us! DON’T try to pull a seemingly stuck foal yourself. If only one leg (with or without a nose), two feet but no nose, or feet whose soles face the sky are present, the foal is probably malpositioned. It is crucial to stay calm, and stand by for assistance. Keep the foal’s nose clear if it is visible.

If everything goes as quickly and smoothly as usual, the first thing to know after your mare gives birth is the 1-2-3 Rule. Your foal should stand within one hour of birth, and nurse within two hours. Within three hours of birth, your mare should pass the placenta—keep it (in a garbage bag and/or bucket)! If not, or it appears in any way incomplete, treatment for retained placenta should be started within six hours of birth. We should come see the foal in the first 12-24 hours after birth to do a physical exam (to check for congenital abnormalities, fractured ribs, signs of infection, etc.), and measure the IgG level (an antibody that tells us if the foal received adequate immunity from his mother’s colostrum).

Dr. King and Dr. Lacher absolutely love foals and are happy to discuss any questions you may have regarding management of your mare! Please let them know if you have any questions! If you find yourself still feeling nervous and unprepared for your mare to foal out at the end of this article, consider the Springhill Foaling Package. Thanks for stopping by! May your litter box always be clean, and your food bowl full!

Don’t Choke!

Mar 11, 2012 | Ailments, Feed

It seems to me that mammals other than horses – cats, humans, annoying dogs, mostly seem to have a really rough time when they are choking. But should you call Springhill to tell them your horse is choking, they will tell you to stay calm, and wait 30 minutes. How and why is this?? Choke in a horse is a completely different syndrome that the typical “choking” episode you think of in a person. The key difference is that choke in a horse results when there is a physical obstruction in the esophagus, not the trachea.

If you come upon a person who is choking, they will be doubled over, gasping for air. They are suffering from an obstruction of the trachea – the main tube connecting the larynx to the lungs. Horses are prone to obstructing at certain points along their esophagus, such as right behind the larynx (the junction of the mouth cavity, the trachea, and the esophagus). A horse that is choking will appear variably distressed, with feed material coming out of his nose. It usually occurs just after being fed grain, particularly if the horse is known to bolt (devour) his feed, or if feeding time is a bit later than usual. Dried beet pulp and pelleted grain have been implicated as well – water absorbs into these types feedstuffs and a bolus of food can expand mid-transport. Sometimes a mass is visible or palpable along the underside of the neck.

Call Springhill as soon as you notice your horse choking. Remove any feed, hay, and shavings if you think they will eat them, but leave the horse water. Often chokes resolve within 30 minutes of occurrence – the horse appears to get comfortable, the nasal flow stops, and he wants to go back to eating. So Springhill will tell you to wait and watch your choking horse for this amount of time, and then Dr. Lacher or Dr. King will be on their way!

When they get there, they will get ready a long tube, a bucket of water, and a particular sedative, butorphanol, that has a specific side effect of making the horse drop his head. With the head below the blockage, the feed can passively drain back out of his nose. The horse also has a more pleasant and less memorable experience during the next part. The vet will pass the tube through the nose to the larynx, where they will encourage the sleepy horse to swallow the tube (against their own good instinct). Once in the esophagus, they will pass the tube forward to the blockage, and then begin to pump. Slowly and steadily, they will have water pumped through the tube against the blockage, and they will move the tube forward and backward to break up the mass. The water may bring material back out through the nose, or the water may pass through the blockage to the stomach, and slowly carry it along with it (like a large leaf in a shallow stream).

Most chokes resolve this way. Complicated, recurring, and difficult chokes require referral to an equine hospital, where a 3 meter camera is used to examine the entire length of the esophagus. The gastroscope, as the camera is called, is passed to the entrance to the stomach (the cardiac sphincter), and the stomach and part of the small intestine is examined as thoroughly as possible (while we’re in there). This is the same exam used to diagnose gastric ulcers in horses, so don’t be surprised if you end up bringing some ulcer medication home from your visit. The esophagus is examined for abnormalities such as a stricture (narrowed section), diverticulum (pouch that develops off the main tube), or tumor. If a large object is obstructing the esophagus, such as a whole apple (just say no to feeding whole apples!), an instrument is passed through the gastroscope to attempt to retrieve the object.

After a choke, the horse will be uncomfortable and it’s best to give a small, warm soupy mash after a few hours. The vets will give re-feeding instructions when they are at your farm. A horse that bolts his feed can have some large, smooth river stones added to his bucket to make him slow down while he eats. If you are concerned, add some water to your feed and make it into a soup. Just don’t let your feed sit wet for too long – it could become rancid.

One of the most important things to be aware of with choke is the aspiration pneumonia that can result. As the horse attempts to breathe through its nose as the feed is passing out, some of the feed (and all the bacteria living on it) end up in the lungs. It’s called aspiration pneumonia, and it can cause a nasty chain of events if left untreated. Thick pus fills the lungs, and eventually the infection passes into the space between the lungs and the ribcage (the pleural cavity – resultantly called pleuropneumonia), or abscesses may form and can rupture into this space. These infections can end up with the horse being hospitalized for IV antibiotics, and drainage of the pleural cavity with a chest tube. Pneumonia that has advanced to this stage can be extremely difficult and expensive to treat, and many horses eventually succumb to the infection.

It is therefore very important to have us out at some point to check your horse’s lungs, at the very least pay close attention to your horse’s breathing for 3-5 days after the choke episode. This is especially important if the horse is a chronic choker. Look for increased rate and effort – normal respiration rate is 12 to 20 breaths per minute (watch the flank or put a hand a few inches from the nostril). You should be calling if you see significant nostril flaring, a large abdominal movement, or obvious rib excursions with breathing. Fever should also be reported (>102F). Horses with pleura-pneumonia will begin to act colicky – usually anxiously turning to look at their girth. Proper management of choke can be a smooth, simple experience or can be a fatal event.

On the lighter side, I am full-swing back into my Tony antics – cat-scanning trailers, running off the new neighborhood stray, and defending the clinic from other dangerous foes! I barely limp any more as I charge across the grassy yard toward the woods again. Keep me posted with ideas you want to see discussed on our blog! May your litter box be clean, and your food bowl full!