It is spring time in the Northwest and time to make sure
your equine partner is healthy and ready for the adventures you have planned
this season. We are blessed to live in
an area that offers boundless wonderful places to enjoy our horses in the great
outdoors as well as an active local equine community offering a staggering
variety of clinics, lessons, shows and play days to attend with all of your
horse crazy friends. Here is what you
need to know about equine health as you plan your events this summer!
Vaccinations
We are so lucky to live in a time when vaccinations can be
viewed as superfluous by a great number of the population. Because of vaccinations we no longer see the
deadly diseases that our parents and grand parent’s generations had to endure. Many of the life-threatening illnesses are
rarely seen in this modern world thanks the to technology of vaccinations and
preventative medicine. With that said,
there is such a thing as too much of a good thing and the old standard of twice
yearly 5-way administration to all horses is no longer appropriate. Designing your vaccination protocol should
take into consideration not only the age and health of the horse to be
vaccinated but what that horse’s likely exposure is going to be for the
year. We have the option of combining
all of those products into a single shot for those needle shy or difficult to
vaccinate horses and we also have the ability to split the products into
multiple vaccinations to minimize overloading the immune system at one go. For many of the respiratory diseases we also
have the option of going with an intra-nasal vaccination which further
diminishes the introduction of adjuvants into the system. Here is a brief overview of the vaccinations
to consider for your horse.
Core Vaccinations:
These are the vaccines that are recommended annually to all healthy
horses regardless of travel or living conditions in the contiguous United
States.
Tetanus: The gold standard back bone of almost all the
combo vaccinations. Tetanus vaccine protects
against the toxin produced by clostridium tetani, a bacteria that is prevalent
in the soil. Because this bacterium is
ubiquitous and lives for long periods in the soil, our horses are exposed to
this disease in their own back yards.
Horses that contract tetanus disease are very likely to die and
treatment is rarely effective and always very expensive.
Eastern/Western
Encephalomyelitis: Often referred to
as Sleeping Sickness this disease is spread by mosquitos and biting flies from
infected birds to horses. This is two disease types lumped into one
category. These diseases are named
according to the areas in which they were first identified and most commonly
seen. There is a third encephalomyelitis
in horses called Venezuelan Encephalitis that we do not typically vaccinate for
in the US and certainly not in the Northwest.
While this is a disease that a concentrated vaccination program has made
fairly rare we do occasionally see cases that pop up in the summer months. Like most of the other diseases in our core
vaccination protocol the mortality for these diseases is very high. 50% mortality rate for WEE and 90% mortality
rate for EEE. This along with tetanus is
the backbone of most of the combination vaccinations. Even horses that do not travel are at some
risk for this disease as it is spread by insects traveling from one place to
another.
West Nile Virus: First identified in the United States in 1999
this disease is a great example of the effectiveness of an active and
aggressive vaccination program. Almost
as soon as the cause of this emerging disease was identified, Fort Dodge went
to work developing a vaccine to attempt to stem the cases of this deadly virus. West Nile Virus causes neurologic symptoms
and tremors which can progress rapidly to recumbency and once down these horses
do not tend to recover. The mortality
rate is reported to be between 30-40% of cases.
In those horses that recover, gait and behavioral abnormalities are
often seen 6 months after infection. We have seen both a decrease in disease
incident as well as an increased likelihood of survival in our vaccinated
population. West Nile Virus was slowed
in it’s spread across the United Stated both by climate and mountains as well
as vaccination. In the Western states we watched in
trepidation as this disease marched across the country then after about 10
years when we didn’t see emerging cases people began to stop vaccinating for
this disease. That was about the time we
started seeing cases here in the Northwest.
In our practice area we have had several cases of confirmed West Nile
Virus in horses. Three of the confirmed
cases that I treated personally happened to survive the disease and one horse
succumbed to the paralysis and had to be euthanized. None of those horses had any history of
vaccination. For some reason, this
vaccine gets the most bad press and love or hate social media that seems to be
where most if it occurs. In my own
personal history of vaccinating thousands of horses annually since 2002 (my
first year in practice the West Nile Virus vaccine was required to be
administered by a veterinarian due to conditional licensing.) I have had only one horse that had what would
be considered a moderate reaction characterized by diarrhea and cramping. He also received a 3 way vaccination and an anthelmintic
that day so there isn’t any way to be sure what he reacted to. Currently the recommendation from the AAEP
for vaccination against West Nile Virus in our area is for every adult horse to
receive annual boosters prior to the onset of bug season.
Rabies: Rabies is also ubiquitous and present in most
mammalian species. Across the United
States we see reservoirs of rabies in certain wildlife populations. In our area the rabies virus seems to be
carried by our bat population. This does
not mean that this is the only way to contract rabies, but it is the most
likely source of wild rabies. There is a
vaccination for all large animals for this disease. AAEP currently recommends annual vaccination
for adult animals. Because in the
Northwest we see very little wild type rabies and because this is one of the
vaccines that in horses seems most likely to cause muscle soreness, our
recommendation for horses that are housed in rural parts of North Idaho to be
vaccinated every 3 years or every other year, following the protocols commonly
used in our small animals.
Risk Based Vaccines: These are vaccines that you and your
veterinarian may deem necessary in order to keep your horse healthy based on
his exposure rate to these diseases.
Equine Herpes Virus
(Rhionpneumonitis): There are two
types of virus associated with equine herpes in horses. Equine Herpes Virus Type 1 (EHV 1) and Equine
Herpes Virus Type 4 (EHV 4). Like the
common cold, this is a disease that varies quite a bit in severity from
individual to individual and circumstance to circumstance. This can be a subclinical mild fever of 24-48
hour duration which may go unnoticed to more serious cases of lethargy,
anorexia, upper respiratory infection and cough. Most horses will be exposed to EHV 1 during
their first weeks or months of life and recover without incident. Recurrent infections occur when young horses
are housed together and entered into competition or training, just like kids
passing a cold around when school starts.
EHV1 also is associated with abortion in pregnant mares as well as weak
non viable foals and it is in this capacity that most aggressive vaccinations
protocols have been implemented in an attempt to reduce viral shedding among
pregnant mares.
More recently this virus has been in the news for the wild
type mutation of the EHV 1 virus that causes debilitating neurologic
disease. The neurologic form of this
viral disease is associated with a much higher mortality rate. Unfortunately this disease is as easy to
spread as our common cold and once it is identified in a population of horses
it becomes a biosecurity challenge to control.
Current recommendations are for horses that are in populations in close
confines (boarding facilities) competing or traveling to areas where many
horses congregate are vaccinated twice annually for EHV. For some horses competing in USEF events,
more frequent vaccination may be recommended. There is no vaccine available for the
neurologic form of this disease. Our
best tool for protecting our populations of horses is to mitigate shedding and
passing of the virus among the population leading to increased risk of the
formation of the wild type virus.
Equine Influenza: This virus is one of the most common
infectious diseases identified in the respiratory track of horses. There are three distinct strains in the
equine population in North America. It
is endemic in the equine population and is most commonly spread by infected
horses. Horses are rarely subclinicaly
infected but may shed virus before the onset of clinical signs. This is why quarantine of all new horses
entering a population for at least 14 days is recommended to be sure you do not
introduce the virus into a new herd.
Like in the human population antigenic drift does occur and as the
equine population immunity waxes and wanes new strains of the virus are
occasionally identified. Vaccine
companies work hard to make sure their vaccines provide optimum protection for
the strains active in the population.
Horses that are traveling and are exposed to other horse populations
should be vaccinated every 6 months for equine influenza.
Strangles: Caused
by the bacterium Streptococcus equi this disease is an upper respiratory and
lymph node infection causing significant fever, lethargy and purulent nasal
discharge as well as swelling of the retropharyngeal lymph nodes that may
impair breathing (hence the name). This
disease is highly contagious and has a long life in the environment and may be
spread from feed bunks, grooming equipment, water tanks etc. There is a very effective intranasal vaccine
for strangles. Horses that have
experienced the disease and recovered have variable immunity but are generally
considered protected at that time.
Vaccination of adult horses annually after initial 2 dose vaccination
schedule is based on exposure. We have
seen an uptick in Strangles cases in our area in the past few years.
How do I decide what
to vaccinate my horse for? There are
many variables to consider when you are planning your vaccination program with
your veterinarian. Your veterinarian
will want to examine the horse to determine if he is healthy and able to be
vaccinated. Horses that are ill, weak,
malnourished, struggling with any disease process or have a history of serious
vaccine reactions are poor candidates for vaccination. Vaccinations rely on a healthy immune system
to be effective. Your vet will also
want to know all of your plans for your horse for the year and the type of
activities you are likely to participate in.
If you are taking part in organized shows or part of a show circuit you
may have vaccine requirements that are established by the governing body or
show management. Understanding equine
vaccinations and your horse’s risk is an integral part of the Veterinary client
patient relationship and helps to ensure your horses are protected to the best
of our ability.
What are the risks? The vaccine’s job is to activate the immune
system to recognize the antigen that has been placed in the body. There is a product called an adjuvant (which
for anti-vaccine folks is the major source of contention) that is added to the
antigen to flag the immune system. For
some individuals this will cause local muscle soreness and in some cases a
transient low grade fever. Somewhere
between 2-5% of horses vaccinated will have some reaction of this type. The veterinarian and the vaccination company
like to be aware of this occurrence rate as we are always trying to maximize
protection while minimizing risk for our equine patients. This is another benefit to using a
veterinarian for your vaccinations (besides assuring your horse is healthy and
receiving the recommended vaccinations).
If your horse does have a reaction your veterinarian can help guide you
through that reaction and ensure that we minimize the risk of a repeat reaction
the following year. Most mild reactions
are managed with anti-inflammatories.
Occasionally, we see injection site reactions due to vaccinations. In over 15 years of vaccinating horses I have
had one of these cases from a vaccine I administered and 2 cases from client
administered vaccines. The very worst
reaction to the vaccine is anaphylactic shock.
Anaphylaxis is a severe immune reaction to something encountered in the
body. It can occur with vaccines,
medications and supplements. Typically,
injectable substances are associated with the most severe cases of
anaphylaxis. This is a very rare
occurrence but can be fatal and usually occurs directly after the
administration of the vaccine (ie before the vet’s truck is pulling out of your
driveway).
How are vaccines
administered? Almost all equine vaccines
are going to be given intramuscularly or intranasally. Intramuscular vaccines are generally
administered in the neck before the shoulder and above the cervical
vertebrae. A 20 g 1 – 1 ½ inch needle is
inserted deep into the muscle. The
veterinarian ensures a vein has not been involved in the injection and
administers the entire vaccine.
Intramuscular injections may also be given in the pectoral region or the
in the back of the hind leg. The
pectoral region is a good place for horses that are needle shy though it is
often associated with some dependent swelling.
The back of the leg is a great choice for some of the larger thicker
vaccines (such as pneumobort) but can be an inconvenient vaccination placement
for many of our patients. The neck is the
safest place for the administration of vaccines.
The intranasal vaccine has several benefits. Firstly, it provides excellent immunity for
some of our respiratory diseases.
Strangles, Rhino and Flu can all be administered intranasally. Secondly, it reduces our risk of vaccine
reactions from adding adjuvants to the horse’s system. Thirdly, giving these vaccinations outside of
the combination (in a 5-way or similar) allows us to better time vaccination
with exposure maximizing immunity. It is
more difficult to administer but as the products and applicators evolve we can
teach our patients that this administration is painless if not entirely
pleasant.
What is the minimum I
am required to give my horses? Because
the majority of the core vaccination protocol is limited to diseases that are
not spread horse to horse and do not pose a risk to the general population
other than to your own individual horse, the choice to vaccinate against these
potentially deadly diseases is entirely your own as long as you understand the
risk that if your horse were to contract any of these diseases his risk of
death is high with West Nile Virus having the highest percentage of
survivability at 2/3 of the horses that contract the disease surviving. If I were to choose just one of the core
vaccinations to administer to my horses it would be tetanus. Tetanus is everywhere and once contracted is almost
impossible to treat. If your horses are
isolated and stay home and do not commingle with other horses they are not
endangering the equine population.
However, if you take your horse to events and gatherings of horse people
where they are within 14 feet of each other, stabling overnight or sharing a water
source, it is your responsibility to help to ensure the health of the equine population
at large by vaccinating your horse for the respiratory viruses. One unvaccinated horse shedding virus and
entering into a population of horses can cause an outbreak of a disease that
can derail the equine activities in that area forcing closure of barns,
cancellation of events and at worse, the death of other horses. You do not have to inject your horse with
anything if you are opposed to the practice, but please, for the sake of my
patients, my own horses, my friends horses and my fellow competitors out there,
administer at least an intranasal flu vaccine prior to going out with your
horse.
What about titers? “Titers” refers to a test that measures levels
of protective antibodies in the horses blood and estimates their protectivity
to certain diseases. Titers are
currently available for many of our common disease including West Nile Virus,
Strangles, Rhino and Influenza.
Unfortunately we do not currently have good population data that is conclusive
as to what levels of titers in the blood are considered protective. So, for a horse that has vaccination
reactions, especially serious ones, running titers may give us some information
about that horse’s immune status and at least give a sense of comfort as to the
choice not to vaccinate. I believe as we
move into the future these titers will become better understood and more
readily available so that we can better adapt our vaccination protocols for
maximum benefit. Just as our deworming
protocols have changed and the frequency and ease of fecal egg counts have increased,
titers are likely to be tool of the future.
Traveling
In the state of Idaho we are required by law to have a
current brand inspection on any horse in our possession. This is especially important when traveling
with our horses. In addition to this
requirement, the majority of the neighboring states also require either a
health certificate or a current coggins test or both depending on the state of
destination.
What is Coggins?
Coggins is a blood test for Equine Infectious Anemia. This is a debilitating and sometimes life threatening
disease that was first recognized in the early part of the 20th
century. Because the disease causes
untreatable anemia it can severely impact the performance of the animal. In an attempt to stem the spread of the disease
the federally regulated testing was implemented in the 1970’s using a test
developed by Dr. Leroy Coggins. Equine
infectious Anemia is spread in the population from infected horses which may or
may not be showing signs of disease by biting horse flies. Currently the incidence rate in the United
States is fairly low but we do see pockets of the disease appear in populations
from time to time. Recently there was a
herd of infected horses in the Gallatin Gateway area of Montana.
You are required to have a negative Coggins within either 6
months or 12 months of entry into a state and the requirement varies quite a
bit from state to state. You can
research the state requirements yourself by visiting the APHIS website https://www.aphis.usda.gov/aphis/ourfocus/importexport
For Washington, Oregon and Montana we can issue a joint health
and Coggins that is good for 6 months.
Each state requires an individual permit number and Montana requires a few
extra steps and a 5$ fee/horse as well as notification or travel into the
state.
It is not unusual for events or facilities to require negative
Coggins from horses prior to an event even if the horses are in state. Plan ahead for your travel and be sure you
have your paperwork in order well before your departure date. I don’t know about other vets, but I’m sure I’ve
lost years of my life stressing about other folk’s emergency travel papers on
Friday evenings before a Saturday departure.
There is no reason not to plan ahead for those events. Your veterinarian will thank you.
That sums up the needs for horses that will be hitting the
road with their adventurous owners this season.
Stay tuned for another installment about biosecurity and minimizing your
horse’s exposure to the disease that are out there ready to put a serious
damper on your summer of fun!
