Health update

Our Old Dominion ride photo by Becky Pearman. Good thing she took the photos in the first 2 miles!!

Sunny is doing great at home, you would never know he had a problem last week. He is running around the field having fun, and we have enjoyed some light bareback riding at home.  His 1 week recheck bloodwork showed his CK value normal and his AST returning to normal as anticipated (The AST has a much longer half-life of 7-8 days in the horse, so in 1 week the value was about 50% decreased).  However his CBC, checking his white blood cell counts and red blood cell counts, showed decreases in two types of white blood cells, neutrophils and lymphocytes.  This raised a red flag in my mind for Anaplasmosis. Both Poptart (http://poptartthearabian.blogspot.com/search?q=anaplasma) and Rogan tested postive and were treated for this in 2016, so I know it is present at my home.  Anaplasma phagocytophilum is a tick borne disease that can cause a variety of symptoms including fever, lethargy, muscle stiffness, anorexia, edema, and skin hemorrhage/petechia, and low neutrophils and lymphocytes among other signs.  It is carried by Ixodes (Deer) ticks.  I also found a 2008 case-report (http://onlinelibrary.wiley.com/doi/10.1111/j.1939-1676.2008.0115.x/full) of a horse having a severe episode of tying up at the same time as an acute infection of Anaplasmosis; this association would have to be studied more to know if Anaplasma can cause tying-up or if it was just a coincidence, but it is certainly on my radar!  Anaplasmosis is typically treated with oxytetracycline or doxycycline and most horses respond well.

So, being the veterinarian that I am, who likes to have solid data, I sent out testing for Anaplasmosis, Vitamin E and Selenium blood levels, and genetic testing for type 1 PSSM (polysacchride storage myopathy) which is found in Rocky Mountain Horses.

Shockingly (LOL), I also have spent a lot of time researching PSSM and horses that have exertional rhabdomyolysis in general.  I hypothesize that "normal" horses do not have episodes of tying-up unless caused by external factors such as exhaustion, dehydration, or electrolytes abnormalities (ie potentially after 50-100 miles of riding).  Otherwise, I think research will eventually show underlying abnormalities in all other horses that have exertional rhabdomyolysis. Unfortunately medical research is not at that point yet, so many episodes are labeled idiopathic (or we don't know).  It could be genetic abnormalities as identified with PSSM or an infectious cause that may temporarily affect muscle such as with Anaplasma, or something else.  Currently, research with muscle biopsies group the causes of expertional rhabdomyolysis into different causes including PSSM 1, PSSM 2, and RER (recurrent exertional rhabdomyolysis); there is genetic testing for PSSM 1. The PSSM types are found in 20+ breeds, most commonly in QH and stock types as well as drafts and warmbloods (but also in gaited breeds). The RER types are found in thoroughbreds, arabians, and standardbreds. The underlying mechanism that causes the tying-up is different depending on the underlying abnormality.

Currently the management recommendations are similar for all types of exertional rhabdomyolysis, but essentially every horse is an individual with their particular needs and responses to different diets and exercise regimens.  Diet -- as low NSC (starch + sugar) as practical and add fat as needed for calories(the goal being 20-25% of daily calories in the form of fat).  Exercise-- every day is the best, even if it is only for 10 minutes and 24/7 pasture turnout is a must as well, which is easy as my horses live out with run-in stalls.  I can manage the diet readily enough, but the daily exercise will be tough; hopefully several times a week will suffice as it has for the last 10 years of his life before this episode.   I will admit that I started jogging with the horses on Friday as I certainly don't have time to exercise myself and Sunny after a full day of work.  And if I take Sunny, why not also take Rogan who is fat and needs exercise!  I also figured I would be more balanced with a lead rope in each hand, LOL!  I will have to get a photo next time.  They did better than expected (we only went 2 miles) and I think with a little practice I will have some reliable jogging partners, LOL!

On the diet, after obsessively researching all the locally/readily available options I have decided on Triple Crown Senior which is 11.7% NSC and 10% fat by weight. I decided to err on a lower NSC with a lower fat, rather than returning to Purina Ultium which as an NSC of 16% and fat of 12.4%; however the Ultium is still certainly a good option depending on availability and Sunny's taste preferences.  The food I was feeding, Nutrena ProForce Fiber has about a 20% NSC and 12% fat, good for most horses, but I would rather go lower on the NSC since Sunny had a tying-up episode.  I plan on feeding 3 qts (about 3 lbs) of the TC Senior, 1 qt Alfalfa pellets (about 2 lbs), 2 cups (1/2 lb) of stabilized flax, and 1 oz of California Trace Supplement am and pm.   This doesn't quite meet the 20-25% fat recommendation, but is certainly within the low NSC recommendations, and it is a big change from the Omolene 500.  I may end up reducing the alfalfa pellets and replacing with more senior to increase the portion of daily calories from fat, but I like the alfalfa pellets for the extra calcium to help buffer the stomach and hopefully reduce ulcers.  I will at least keep the alfalfa on hand for the rides!  The flax adds additional Omega-3 fatty acids and extra fat.   And, of course, I will adjust accordingly based on his current body condition score.

So that is the plan for now, and I continue to wait for test results... If he is positive for Anaplasmosis I will treat and continue to ride him lightly at home, but will hold off on heavy conditioning until after treatment.  If he is negative, then I will slowly and progressively resume conditioning in the next week or so.   For now I am thoroughly enjoying the bareback gaiting and dressage.  I love riding him bareback during our learning about gaiting, as I can really feeling his back change as he speeds up or slows down, or tenses and relaxes. The nicest gait so far is a 4-beat rhythmic gait about 5-6 mph, where his head and neck are relaxed but lifted in a natural posture and as he relaxes I can really feel his loin and back lift.   Hopefully this summer I will be able to submit a video to the Kentucky Mountain Horse Association for certification and permanent registration!