“So, what do you really do at work?”
This is the most common question my Facebook ‘friends’ ask me when I see them face-to-face.
Contrary to what they’d usually see on their FB newsfeed, I don’t just
simply drive to the airport, hop on a plane and visit places for work. There are actually more than a thousand
things happening behind those photographs of beautiful destinations, delicious
and great-looking dishes as well as drinks (well, I only order apple or orange
juice most of the time).
Actually, my FB friends
just can’t believe that in between my FB and Instagram postings, I’ve also been
seriously mastering the art of visiting a piggery, speaking with the farm
owner, manager, staff or their consulting veterinarian, listening and counting
the pig’s cough, checking the herd’s poo, collecting some blood samples,
cutting dead pigs up, closely examining their internal organs and saving some
thumb-size tissue samples if necessary—keeping these in small, transparent jars
containing formalin solution and submitting these to the laboratory… Then when
the test results come in, interpreting and coming up with a comprehensive
case report.
Of all the activities I’d enumerate, listening to and counting the pig’s
cough has been the most interesting and exciting thing for my friends, so far! Some curious ones would innocently ask if I’d
auscultate a pig’s chest using a stethoscope like what their GP would do to them while being asked to deeply inhale and exhale when they or their kids are examined for
respiratory issues. I’d politely reply
that because my patients love to squeal when manually handled, and modern-day
pig farming involves hundreds or thousands of pigs on one site, herd
examination is more appropriate—thus attentively listening to the pigs’
cough—whether it’s dry or moist, long or short episode, and at the same time
counting them are equally important.
IN THE PHILIPPINES, there’s this dish with Spanish origin called bopis
which is made out of boiled pork lungs and heart—patiently cut into bits and
pieces and sautéed in onion, tomatoes and chilies. Unlike most of my friends, I, honestly, don’t like
eating bopis and my repulsion from this Filipino-favourite pulutan (a dish that
is slowly eaten while enjoying some bottles of beer or shots of spirits)
started even before I became a veterinary student. I just can’t handle chewing a spoonful of
this smooth, soft and rubbery dish with those tiny, cartilaginous prickles from
the pieces of offal tickling my tongue.
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| http://pulmonaryfibrosisresearch.org/nsip-2 |
Only when I enrolled in vet school and started studying veterinary
anatomy did I learn that those rubbery portions that I felt when I chewed a
spoonful of bopis were part of the functional tissues of the lungs that, when
examined under the microscope, are actually tiny sacs made up or lined with
flat and cuboidal cells. These are
called alveoli, which are perfectly known as air sacs because this is exactly where
blood oxygen and carbon dioxide exchange occurs!
Oxygen,
the life-supporting gas in animals, is actually taken in by the pig as it
inhales air through its nostril. The air
will then pass through the left and right nasal passages—each of these contains
lower and upper curled bones called turbinates. Dr. Lumbao, my Veterinary Anatomy lecturer said they’re like turbines, while
Muirhead and Alexander in their book Managing Pig Health described these
turbinates as four hair curlers strategically placed inside the pig’s nose;
these nasal ‘scrolls’ warm the inhaled air and at the same time creates air
turbulence as the pig breathes. As a
result, larger particles (such as dust) are thrown out and attached to the
mucous lining the airways.
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| https://www.pig333.com/pathology-atlas/rhinitis-and-turbinate-atrophy_94 |
Toxins produced by bacteria called Pasterurella multocida in synergy with
the Bordetella bronchiseptica can lead to failure of the turbinate-bone growth
and at the same time promoting its destruction—in the end the pigs’ snout will
look distorted, affected pigs may be heard sneezing—a disease called atrophic
rhinitis.
The pigs’ airway, like other mammals, starts off as a series of 30
cartilaginous rings making up a windpipe or trachea. This tube gradually branches down into three
smaller tubes (bronchi)—actually unique for pigs because other domestic farm
animals only have two. These tubes continue
to branch in right angles until it gets very tiny and microscopic pipes
(bronchioles) that terminate into each of the air sacs. These cartilaginous airways, I’ve learned,
are the spikes that actually tickled my tongue the first and last time I had some
bopis!
The airways are lined with mucous membrane where there are microscopic
structures that resemble a pedantic display of 'goblets in a cupboard' thus aptly
called ‘goblet cells’. These cells
produce mucous which, with the help of another microscopic feature of the
airway—the hair-like projections (cilia) moving in a wavy manner, helps carry
the nasty particles out from the lungs to the throat. This is called 'mucociliary escalation'.
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| https://www.studyblue.com/notes/note/n/chapter-4-the-tissue-level-of-organization/deck/5452448 |
A PIG’S COUGH IS A DEFENSIVE REFLEX, considered protective as it aims to
clear the lungs and the airways from irritants and foreign particles including
harmful microbes that cause diseases.
Unfortunately however, coughing is also an excellent way of spreading
pig respiratory diseases especially when the animals at risk and with varying status of immunity are sharing the same air space.
Viruses are too small; they can survive the mucociliary escalation and
still reach and invade the pigs’ air sacs.
Mycoplasma hyopneumoniae (Mhyo), a pig respiratory pathogen, loves to
colonise and infect those tiny projections (cilia) lining the airways— so these will eventually stop
moving, and start clumping together. The first branch of the windpipe that's closest to the external environment— the extra-bronchus that is unique in pigs supplies the right cranial lung
lobe which is most commonly affected by this disease initially (photo above).
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| http://www.allwidewallpapers.com/swine-disease-prrs/ |
I knew what you're thinking, the pig’s immune system naturally secretes antibodies
against Mhyo [Em-hayO] but these supposedly counteracting proteins can’t reach
their ‘targets’ that are comfortably sitting on top of the clumped respiratory
cilia. So Mhyo will progressively multiply,
white blood cells that serve as soldiers turn feeble and can’t keep up, and the
mucosal lining will eventually peel off leaving the pigs’ airway devoid of
goblet cells. Loss of goblet cells
simply means loss of mucous production resulting to a pig suffering from a dry,
non-productive cough with very long episodes!
SO WHENEVER OUR competent technical representatives and I are doing our
job in the pig sheds or shelters, we’d wake the pigs up, continuously disturb
them to stimulate them to cough. With
our tally counter and stop watches on, we’d then patiently listen to and count
the coughing bouts within nine minutes.
Based on previous studies that checked the DNA of the microbes and the
specific antibody level in a herd, a hundred pigs that cough twenty-four times
or more in nine minutes would simply mean that a herd is unhealthy.
Sometimes it could get a bit complicated, as Mhyo is a primary invader—the
damaged pig airways are now open to secondary respiratory pathogens! Glasser’s disease, mostly occurring in weaners, is caused by a bug
that damages the walls of the blood vessels in the lungs and other vital organs. 'Leaky' blood vessels result in a chest cavity containing fluids and appear like they're covered in feta cheese or spider
web. APP (Actinobacillus
pleuropneumoniae) infection can also occur, mostly in grower or finisher pigs, and the toxins produced by this bug
shatter the red blood cells, and create injury to the smooth covering (or pleura) that lines the
chest cavity and the lungs. The clinical signs could start as quick as 12 hrs after the disease agents have been inhaled by the pig... and with the characteristic feature of the condition where parts of the lungs are attached to the rib cage, this pleuropneumonia is obviously very painful— the pigs adopt a dog-sitting position while gasping for air and can only manage to cough once or twice per episode! Microscopically, the air sacs will then be filled and densely packed with
white blood cells; so to sum it all up— these are basically the reasons why a pig's lungs are dark, firm and swollen, uncollapsed, attached to the rib cage, and most of the time the cut surface is oozing with blood upon
examination!
Yes, pig veterinarians, unlike companion animal and equine vets, or even
unlike physicians, are highly privileged to be able to see the changes secondary
to disease (or lesions) in their patients' internal organs by cutting up a
representative pig—either dead or alive then euthanised—from a sick herd. We can conveniently examine their 'plucks' while on the field
or even in the abattoirs—just like what the vets and meat inspectors in the
slaughter lines would routinely do as part of their post-mortem check to ensure that meat, including edible offal are fit for human consumption.
BY VISITING THE herd, listening to their cough, looking at the lung
lesions, and interpreting the lab test results, swine veterinarians can formulate
solutions and give recommendations which, I believe, can provide assistance in
promoting pig health and in producing more ‘pork’ for Australia and the
world.
…and when I say ‘pork’ it includes a healthy lung, as well. That would mean more pork lungs for the bopis
recipe of my friends, too!
.
