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Myofascial Pain Syndrome, myofascial trigger points and trigger points in Veterinary Medicine

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Myofascial Pain Syndrome (MPS) a is a painful condition related to myofascial trigger points (TP) in skeletal muscle. The aim of this study was to perform a literature review on the etiology, pathophysiology, diagnosis and treatment of MPS in veterinary medicine. The research sites used for this purpose were: Scientific Electronic Library, PubMed and Medline. The inclusion criteria for the papers were: must be written in English; published between 1990 and 2018; include the following keywords: myofascial pain syndrome veterinary/dog/canine/cat/feline/horse/equine, trigger points veterinary/dog/canine/cat/feline/horse/equine. Through the review, it was observed that veterinary clinical studies are scarce, and the articles found lack information such as MPS description, incidence and specific treatment techniques in dogs and horses, and no studies in cats were found.
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Braz J Vet Res Anim Sci. 2020;57(2):e164351
https://doi.org/10.11606/issn.1678-4456.bjvras.2019.164351
REVIEW ARTICLE
ISSN Online 1678-4456
Myofascial Pain Syndrome, myofascial trigger points and trigger
points in veterinary medicine: a review
Revisão: Síndrome Dolorosa Miofascial, pontos gatilhos miofascial e
pontos gatilhos na medicina veterinária
Nadia Yuri Shimosaka Sato1 ; Bárbara Bu Blumer Bastos2 ; Marco Aurélio Amador Pereira1 ;
Karina D’Angelo Campos1 ; Aline Magalhães Ambrósio1 ; Maira Rezende Formenton1 ;
Denise Tabacchi Fantoni1
1 Universidade de São Paulo, Faculdade de Medicina Veterinária e Zootecnia, Departamento de Cirurgia, São Paulo – SP, Brazil
2 Hospital Veterinário São Sebastião, São Sebastião – SP, Brazil
ABSTRACT
Myofascial Pain Syndrome (MPS) a is a painful condition related to myofascial trigger points (TP) in skeletal muscle.
e aim of this study was to perform a literature review on the etiology, pathophysiology, diagnosis and treatment of
MPS in veterinary medicine. e research sites used for this purpose were: Scientic Electronic Library, PubMed and
Medline. e inclusion criteria for the papers were: must be written in English; published between 1990 and 2018;
include the following keywords: myofascial pain syndrome veterinary/dog/canine/cat/feline/horse/equine, trigger points
veterinary/dog/canine/cat/feline/horse/equine. rough the review, it was observed that veterinary clinical studies are
scarce, and the articles found lack information such as MPS description, incidence and specic treatment techniques in
dogs and horses, and no studies in cats were found.
Keywords: Myofascial Pain Syndrome. Trigger points. Horses. Dogs.
RESUMO
Síndrome Dolorosa Miofascial (SDM) é uma condição dolorosa relacionada aos pontos gatilhos miofasciais (PG) no
músculo esquelético. Este trabalho tem como objetivo realizar uma revisão bibliográca sobre a etiologia, siopatogenia,
diagnóstico e tratamento na medicina veterinária. Foram utilizados sites de pesquisas Scientic Electronic Library,
Pubmed e Medline. Os critérios de inclusão estabelecidos foram: ser escrito em inglês; no período de 1990 a 2018;
ter as palavras chaves para busca: myofascial pain syndrome veterinary/dog/canine/cat/feline/ horse/equine, trigger points
veterinary/dog/canine/cat/feline/horse/equine. Após a revisão observa-se que faltam estudos clínicos em medicina
veterinária, sendo que os artigos encontrados se limitam à descrição, incidência e técnicas pontuais em cães e equinos,
não sendo encontradas referencias em felinos.
Palavras-chave: Síndrome Miofascial Dolorosa. Pontos gatilhos. Equinos. Cães.
Correspondence to:
Nadia Yuri Shimosaka Sato
Universidade de São Paulo, Faculdade de Medicina Veterinária
e Zootecnia, Departamento de Cirurgia
Av. Prof. Dr. Orlando Marques de Paiva, 87, Butantã
CEP: 05508-900, São Paulo – SP, Brazil
e-mail: nadiayuriss@usp.br
Received: November 26, 2019
Approved: February 22, 2020
How to cite: Sato NYS, Bastos BBB, Pereira MAA, Campos
KD, Ambrósio AM, Formenton MR, Fantoni DT. Myofascial
Pain Syndrome, myofascial trigger points and trigger
points in veterinary medicine: a review. Braz J Vet Res
Anim Sci. 2020;57(2):e164351. https://doi.org/10.11606/
issn.1678-4456.bjvras.2019.164351
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Braz J Vet Res Anim Sci. 2020;57(2):e164351
Introduction
Myofascial Pain Syndrome (MPS) is described in
medicine as a painful condition related to the presence
of myofascial trigger points (TP) in the skeletal muscular
system. Its presentations may be isolated, associated with
concomitant chronic diseases, active or latent (Borg-Stein
& Iaccarino, 2014; Fernández-de-Las-Peñas & Nijs, 2019).
In humans, it aects muscles, connective tissue and fascia,
especially in the cervical, scapular and lumbar regions
(Teixeiraetal., 2001; Yengetal., 2001).
TP or myofascial trigger point is dened as a focus of
muscle hyperirritability that generates a painful stimulus
to the skeletal muscle system. TPs might be palpable and
are associated with strained muscle bands or “knots”.
If manual pressure is applied to the TPs, the patient feels
local and referred pain (Borg-Stein & Iaccarino, 2014;
Fernández-de-Las-Peñas & Nijs, 2019; Gerwin, 2014;
Simons, 2002; Teixeiraetal., 2001).
In humans, the prevalence of MPS ranges from 21% to 30%
in the general population or even 85% to 90% in people
with chronic pain (Borg-Stein & Iaccarino, 2014). MPS is
described as a strong limiting condition by people who
have it, since it is related to work absence and increased
time of low back pain treatment. Furthermore, in oncology
patients, it may increase morbidity and mortality due to
its intrinsically associated low blood levels of magnesium
and 25-hydroxyvitamin D (Landis & Koch, 1977; Teixeiraetal.,
2001; Yengetal., 2001).
e rst study describing TP was published in 1991 and
was performed in dogs by Janssens (1991). Hong & Simons
(1998) later used rabbits as an experimental model to study
the pathophysiology of TP and demonstrated that TP, also
referred pain and muscle contracture, are linked to integrative
spinal cord mechanisms and excessive acetylcholine release.
e growing interest of veterinary professionals in
emerging disciplines such as physical rehabilitation and
sports medicine, as well as the increasing incidence of
chronic diseases that aect the locomotor system in horses
and companion animals, knowledge about MPS and TP is of
great importance (Simons & Dommerholt, 2006; Wall, 2014).
is study aims to present a literature review on the etiology,
pathophysiology, diagnosis and treatment of Myofascial
pain syndrome and myofascial trigger points in veterinary
medicine, with an emphasis on dogs, cats and horses.
Materials and Methods
e literature review was performed in 3 steps: search
for journals, eligibility evaluation and development of
the discussion based on the selected articles. e search
for journals was performed by a reviewer, within a three
month period, by electronically searching the Scientic
Electronic Library research sites (Scientific Electronic
Library Online, 2019), PubMed (National Center for
Biotechnology Information, 2019) and Medline (Centro
Latino-Americano e do Caribe de Informação em Ciências
da Saúde, 2019) for articles and scientic papers related to
MPS in veterinary patients.
e inclusion criteria were: the articles must be written
in English; published between 1990 and 2018; and include
the following keywords: myofascial pain syndrome
veterinary/dog/canine/cat/feline/horse/equine, trigger
points veterinary/dog/canine/cat/feline/horse/equine.
Sixty articles and references were selected, 30 of which in
PubMed and the other 30 in Medline. Exclusion criteria were:
theses references, book chapters and citations, abstracts or
references of congress proceedings, studies in other species
and outside the proposed period.
Eligibility evaluation was performed in two stages:
quantitative and qualitative selection. In the quantitative
selection, 45 articles had to be excluded as they were
duplicated, and one was excluded since its publication date
was not within the proposed period.
In the qualitative selection, two reviewers read the 15 articles
and classied each one as: strong, weak or unrelated to the
topic (including articles that were not available). Aerwards,
Fleiss’s Kappa agreement analysis was performed and it
was found that 13 articles showed substantial relation to
the study’s topic (kappa = 0.761468), according to Landis
& Koch (1977). e process of research and eligibility
evaluation is illustrated in Figure1. Technical les of the
articles were prepared containing information on author,
title, species, type of article, results and conclusion. e two
reviewers then developed the discussion.
Figure 1 – Stages of article selection with Electronic Search,
exclusion, quantitative and qualitative eligibility.
Legend: (n): sample number.
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Results
ree observational clinical studies, two prospective
clinical studies, three original articles, four bibliographic
reviews and one case report were selected. One of them
addressed horses, dogs and cats; two were about dogs and
cats; three regarded dogs only; and six concerned horses.
No articles specically addressed cats.
Table 1 details of the technical le used to guide the
discussion on Myofascial Pain Syndrome and Myofascial
trigger point in horses, dogs and cats.
Table 1 – Technical le summarizing the major publications on Myofascial Syndrome and Trigger Points in Horses, Dogs and Cats
Author Title Article
Modality
Species
Materials and Methods Results and Conclusion
Brockman
(2017)
A case study
utilizing
myofascial release,
acupressure
and trigger
point therapy to
treat bilateral
“ stringhalt” in
a 12 year old
Akhal-teke horse
Case Report Horse A 12-year-old Akhal-teke horse
with high exion of the right pelvic
limb underwent treatment with
myofascial release of cervical, sacrum
and ilium muscles, bladder meridian
acupressure (including spine, spine,
lumbar hamstrings) and TP release
from the iliac region. Frequently twice
a week for 1 hour and a half each
session
Massage therapy with myofascial
release, acupressure and TP release
proved to be an alternative for
horses with high limb exion.
In this case report there was a
decrease in the frequency and
intensity of muscle spasms and an
improvement of 50 to 85% in the
incidence of high exion of the
aected pelvic limb.
Downing
(2011)
The role of physical
medicine and
rehabilitation
for patients in
palliative and
hospice care
Original
article
Dog
Cat
Review of the types of rehabilitation
and their benets in palliative
care patients. Therapies such as
heat / cold therapies, massage
therapy, chiropractic, acupuncture and
myofascial TP release were addressed.
Patients in palliative care are most
often carriers of chronic diseases
and dierent rehabilitation
modalities can bring pain relief,
reduce medication use and bring
comfort to terminally ill patients.
Frank (1999) Myofascial trigger
point diagnostic
criteria in dog
Prospective
clinical study
Dog 600 dogs were evaluated according
to the evaluation and diagnosis
criteria of MPS used in humans
with assessment of restricted range
of motion, band palpation, local
sensitivity, jumping signal, contractile
response, muscle weakness or loss of
proprioception, pain recognition and
referred pain in sensitized areas.
The evaluation and diagnosis
criteria of myofascial painful
syndrome used in humans have
proven to be eective in developing
a diagnostic and therapeutic
approach for this syndrome in dogs.
Fryetal. (2014) Acupuncture
for analgesia
in veterinary
medicine.
Review article Horse
Dog
Cat
Review of the indication and
mechanisms of action of acupuncture
Many acupuncture points are near
or associated with regions with
musculoskeletal dysfunction, such
as TP.
Acupuncture should be part of the
multimodal approach for treating a
wide variety of painful conditions,
including TP release.
Formentonetal.
(2017)
Small animal
massage therapy:
a brief review
and relevant
observations
Review article Dog
Cat
This is a review of the main aspects
of massage therapy described in
human physiotherapy, extrapolating
such techniques to small patients
(dogs and cats).
The benets of massage therapy seen
in dogs and cats can be compared
to those seen in humans with pain
relief and applicability in orthopedic
rehabilitation, canine sports medicine,
intensive care and treatment of
nonspecic edema. It is a promising
therapy modality that needs studies
in domestic animals.
Bowenetal.
(2017)
Investigation of
myofascial trigger
points in equine
pectoral muscles
and girth-aversion
behavior
Cross-
sectional
study
Horse Thirty-eight horses with Girth-
Aversion Behaviors were selected for
physiotherapeutic investigation of
myofascial trigger points in equine
pectoral muscles and to correlate TP
pain score with behavioral changes.
Incident of TP in the pectoral region is
described in the armpit region in the
laryngeal portion of the ascending
pectoral muscle, to the right of the
sternum and across the circumference
region and towards the edges of the
muscles.
And horses that presented severe
pain with the manipulation
of TPs showed more evident
Girth-Aversion Behaviors.
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Author Title Article
Modality
Species
Materials and Methods Results and Conclusion
Janssens (1991) Trigger points
in 48 dogs with
myofascial pain
syndromes
Prospective
clinical study
Dog Forty-eight dogs were studied for
TP recognition and treated with dry
needling technique and anesthetic
inltration. The dogs were divided
into 2 groups and the treatment was
performed weekly for 8 weeks.
Seven points of TPs were identied:
brachial triceps, infraspinatus,
pectineus adductor, long bular,
middle gluteus, iliopsoas and
quadriceps femoral muscles
35 to 60% of the animals showed
favorable response to the treatment
performed.
MacGregor &
Von Schweinitz
(2006)
Needle
electromyography
activity of
myofascial trigger
points and control
sites in equine
cleido-brachialis
muscle--an
observational
study.
Prospective
clinical study
Horse Four horses with signs of TP in the
cleido-brachial muscle underwent
spontaneous electrical activity
evaluation of the muscle at the TP
point (acupuncture point L16) and
control point (acupuncture point
L17 or ST10).
The study demonstrated
spontaneous electrical activity
(SEA) in the equine cleido-brachial
muscle, sites determined by
palpation to be active PT compared
to SEA at control sites.
There is incidence of TP in equine
cleido-brachial muscle
Pellegrinietal.
(2020)
Equine
acupuncture
methods and
applications: A
review
Review article Horse Review that discusses the applications
of acupuncture and its eastern
medical philosophy in equine health,
as well as the main techniques used
to stimulate acupuncture points in
equine practice.
The techniques used in acupuncture
are based on endogenous /
homeostatic mechanisms to lead
to ‘self-healing’. Acupuncture can
be considered complementary and
integrative in a setting of equine
clinical practice.
D.
Ridgway (1999) Acupuncture as a
treatment modality
for back problems
Original
article
Horse Discusses acupuncture techniques
and methods, including dry needling,
electro acupuncture, acupuncture
using hypodermic needles, and
injection of various solutions at
acupuncture sites in patients with
radiculopathy and MPS.
Acupuncture treatment may have
benets for horses with diuse MPS,
but it is essential to combine other
therapies for the recovery of horses
with radiculopathies.
Rogers (2012) Acupuncture for
Equine Paraspinal
Myofascial Pain
Prospective
clinical study
Horse Study on the incidence and treatment
with acupuncture of TPs in purebred
horses in the neck paraspinal muscles,
thoracolumbar area, croup (sacroiliac,
gluteal and hip area) and triceps and
hamstring muscles with identication
of pressure-reactive zones with
assistance probe (ZRPS).
Acupuncture treatment following
ZRPS standards presents
favorable response with improved
performance of animals in a short
time. In this study, a higher incidence
of right hip pain was observed, with
compensatory pain in the left neck
over the C5-C7 vertebrae.
Von Schweinitz
(1999)
Thermographic
diagnostics in
equine back pain
Original
article
Horse Description of the thermographic
diagnostic method in low back pain
horses.
Thermography is a fast, safe,
noninvasive complementary
assessment method that can assist
in monitoring response to low back
pain treatment in horses.
Wall (2014) Introduction to
myofascial trigger
points in dogs
Review article Dog Review of etiology, clinical
manifestations, diagnosis and
treatment of TP in dogs.
The presence of TP in dogs leads to
pain and locomotor dysfunction.
Thus, the development of
identication skills, as well as
familiarity with the most aected
regions of TP and nally the
knowledge of treatment techniques
are necessary for the eective
management of TP in dogs.
Table 1 – Continued...
Discussion
Dogs and cats
Although the term MPS is not routinely used in companion
animals medicine, the existence of TP in dogs has been known
since the 1990s. TP have been described in the following muscle
groups that are overloaded by the hip joint: exor (including
iliopsoas), adductor and extensor muscles (Wall, 2014), pectin,
long bular, middle gluteal and quadriceps femoris muscles
(Janssens, 1991). ere are also reports in muscles overloaded
by the thoracic limbs: infraspinatus, deltoid and triceps brachii
muscles (Janssens, 1991; Wall, 2014).
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e clinical manifestations of patients with MPS or
TP may include sensory, motor or autonomic alterations.
Its sensory characteristics are related to pain. Human patients
report diuse and deep pain that is hard to locate when
the tense band (TB) is palpated. Dogs can show behavior
changes such as limb withdrawal or vocalization when TP
are manipulated (Wall, 2014).
Motor characteristics may be related to muscle atrophy,
muscle weakness, decreased range of motion and local
twitch responses (LTR). e presence of a TP in a muscle
can inhibit the contractile strength of adjacent muscles,
leading to muscle weakness. Muscle atrophy may be due
to disuse of the limb. LTR is a spinal cord response, where
contraction of a taunt band is observed aer direct TP
stimulation with manual palpation or introduction of
a needle. e presence of LTR in dogs corroborates the
existence of TP (Wall, 2014).
TP consist of muscle bers with intensely contracted
sarcomeres with increased diameter and are usually
called “knots”. However, the pathophysiology involving
the formation of these “knots” is not yet well understood.
However, in 2004 a hypothesis was raised and suggested
that muscle injury leads to high intracellular calcium
concentrations (outside of the sarcoplasmic reticulum) and
excessive acetylcholine release due to a motor end-plate
dysfunction, which results in the shortening of sarcomeres
(Wall, 2014).
e factors described as having the greatest impact on TP
and MPS formation and perpetuation are postural changes
due to orthopedic problems, postoperative or post-traumatic
complications, pain related to neuropathies and arthropathies,
especially osteoarthritis, and most frequently it is associated
with stress mechanisms due to chronic muscle overload
(Fryetal., 2014). It is not known whether nutritional or
metabolic factors may contribute to the formation of TP
and MPS (Wall, 2014), however Formentonetal. (2017)
suggests that cancer patients undergoing surgical treatment
with extensive manipulation show myofascial adhesions,
as described in humans.
Very oen, MPS and TP are neglected and may cause
behavior changes or clinical signs related to pain chronication
processes. In these cases, peripheral or central sensitization
mechanisms are activated, which result in decreased pain
threshold and increased peripheral receptor response or
in physicochemical changes in the central nervous system
that increase neuron excitability, respectively (Wall, 2014).
e criteria for identication of TP are well established
in humans, as described in Table 2. us, Frank (1999)
applied these criteria to dogs with general lameness, without
specifying the studied muscle groups and conrmed the
presence of TP in dogs, showing the similarity between
the diagnosis in both species.
e animal’s reaction to TP manipulation varies according
to the severity of the problem and the response of each
patient, however some behavioral ndings may lead to a
denite conclusion that the animal is in discomfort, such
as looking toward the palpated region, aggressiveness,
physiological changes such as pupil dilation and/or if the
owner reports falling down or tiredness aer exercise
(Frank, 1999).
Referred pain in animals is controversial, as most
authors point out that animals cannot describe the intensity
and the delimitation of the aected area, leading to a
compromised assessment (MacGregor & Von Schweinitz,
2006). On the other hand, Frank believes that animals may
exhibit behavior changes such as self-mutilation, licking
the aected area, rubbing their ears or shaking their heads
as reported by the owners, or may show limb withdrawal
aer applying non-painful tactile stimuli, in a similar way
to the assessment of tactile allodynia in the region adjacent
or caudal to the TP performed by the veterinarian during
the physical examination (Frank, 1999).
Some TP palpation techniques can be employed by
physiotherapy professionals, such as at palpation, in
which an evaluation is performed with nger pressure
along the muscle ber in a right angle supported by a rm
Table 2 – Modied from Simons (2002)
Clinical criteria for diagnosis of active trigger points
Clinical history
Complaint of pain or observation of behavioral changes
related to acute, chronic symptoms or repetitive muscle
overload of some region.
Pain of mild to moderate intensity related to some movement,
positioning or even severe intensity when the pain is
persistent.
Diagnostic Findings
Restricted range of motion with painful component
Presence of palpable taut band
Sensitivity to palpation at the site of muscle straining bands
Reproduction of pain in the patient
Referred pain
Weakness
Autonomic signs (skin heat or erythema, tearing, piloerection)
Conrmatory Findings
Local contraction induced by palpation or needling when
manipulated TP observed on physical or ultrasound
examination.
Referred pain
Visualization of “terminal plate noise” when electromyography
TP needling
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adjacent structure, such as the bone used for palpation of
the infraspinatus, supraspinatus or psoas major muscles.
Another technique is pincer palpation, in which the
evaluation of part of a muscle is performed by holding it
like a pincer and sliding the muscle bers with the nger
tips. is technique is used to evaluate the triceps, sartorius
and tensor fascia lata muscles, and professional qualication
is necessary to familiarization with the TP recognition
(Wall, 2014). Studies relating thermography, TP or MPS
algometry in dogs are scarce.
e treatment of MPS and TP can be divided into
noninvasive and invasive techniques. Noninvasive treatments
consist of laser therapy, electrotherapy and massage therapy.
According to Wall, low-level laser therapy is widely used
in humans to treat MPS and may also be applicable to
dogs. Electrotherapy is employed in acute and chronic
pain management in dogs, and even though studies on
this topic are scarce, it is believed that it may also benet
MPS and TP patients (Wall, 2014).
Massage therapy is a recent modality with little scientic
evidence in dogs and cats, however Formentonetal. (2017)
reported that manual techniques such as Eeurage, kneading,
petrissage, rubbing, tapping, vibration and shaking can
be applied to dogs and cats and produce benecial eects
such as pain relief. is modality of therapy is applicable to
orthopedic rehabilitation, canine sports medicine, intensive
care and treatment of nonspecic edema. Furthermore,
in cancer patients, massage therapy can produce pain
modulation and consequently increase their quality of life.
e invasive techniques consist of dry needling or
inltration with local anesthetics or saline solution. Regarding
the dry needling technique, acupuncture needles are oen
employed and once the tense band is recognized, the TP
needling is performed until one or more LTR are observed.
e depth of needle insertion ranges from 0.5 to 5 cm
according to the patient’s TP and body condition score, and
the recommended duration of the needling is 5 minutes
(Janssens, 1991).
As for the drug inltration technique, hypodermic
needles and 1% lidocaine are used. e volume ranges
from 0.25 to 2 ml per TP. e recommended interval between
applications in chronic cases is once a week, however it
may be performed aer smaller intervals in cases of acute
low back pain (Janssens, 1991; Wall, 2014). Comparing
the techniques, Janssens observed that the dry needling
technique brought discomfort to dogs, especially due to
its duration, and drug inltration was better tolerated
(Janssens, 1991).
A clinical study performed weekly dry needling or drug
inltrations in dogs diagnosed with MPS for 8 weeks and
it was observed that 60% of them showed improvement.
Moreover, it was found that the dogs responded in two
dierent ways; the group of dogs that had isolated TP located
in the triceps, infra-spinal, quadriceps or adductor and
pectineus muscles showed a good response to treatment.
However, the other group that showed symmetrical TP in
the pelvic limbs or multiple TP presented a poor response
to treatment, and these dogs were even compared to human
patients with bromyalgia (Janssens, 1991).
at study also observed that four points frequently
identied as TP coincide with some acupoints used in
Chinese medicine: the peroneus longus bladder-34, the
adductor-pectineus point liver-10 or 11, the gluteus
medius point bladder-29 and the infraspinatus point
small intestine-10 infraspinatus point. It is unclear what
is the correlation between TP and acupoints and even if
patients undergoing dry needling due to TP may benet
from acupuncture analgesic mechanisms complementarily
(Downing, 2011; Fryetal., 2014; Janssens, 1991).
Horses
In horses, MPS and TP are related to behavioral
changes linked to riding aversion or poor performance
(Bowen et al., 2017; Rogers, 2012). TP in horses have
been described in the cervical and pectoral muscles as
well as in the cleido-brachial muscles (MacGregor & Von
Schweinitz, 2006), axillary region in the laryngeal portion of
the ascending pectoral muscle (Bowenetal., 2017), triceps,
ischio-tibial muscles, neck paraspinal muscles, muscles
aecting the gluteus and hip areas (Rogers, 2012), or they
even aect the muscles adjacent to the thoracolumbar and
sacroiliac spine (Brockman, 2017). Figure2 illustrates the
mapping of TP observed in the pectoral region of horses.
e etiology involves mechanical and nervous stresses,
such as compression, poor posture, chronic or acute
muscular overload and metabolic diseases, due to reduced
local circulation, low oxygenation and pH acidication and
consequent onset of inammation and pain (Bowenetal.,
2017; Landis & Koch, 1977). It may be related to some
diseases such as chronic low back pain in horses, in which
the incidence of TP and neurological changes may perpetuate
local pain, leading to peripheral and central sensitization
processes (Ridgway, 1999).
Based on the diagnostic criteria for MPS in humans,
3 of 5 criteria were observed in equine cleido-brachial
muscles: the presence of palpable taut bands (TB), painful
tense bands upon manual palpation and the presence of
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Braz J Vet Res Anim Sci. 2020;57(2):e164351
LTR aer palpation and application of dry needling in
the studied TP. Furthermore, it was shown that there is
spontaneous electrical activity in the muscle with TP,
corroborating with the Integrated Trigger Point Hypothesis
(2004) (Gerwinetal., 2004; MacGregor & Von Schweinitz,
2006; Wall, 2014).
e electrical activities observed in the study by MacGregor
& Von Schweinitz (2006) are similar to those observed
in rabbits and humans with MPD. Given the release of
acetylcholine, there is depolarization of muscle membranes,
thus resulting in the propagation of negative and positive
potentials. Sarcomere contracture may occur because
depolarization occurs continuously and consequently the
formation of tensioned bands is perpetuated (MacGregor
& Von Schweinitz, 2006).
e diagnosis of TP in a thoroughbred horse was
described aer identifying areas called “probe-assisted
pressure reactive zones” (ZRPS). Rogers (2012) describes
as “probe” a rigid consistency and smooth surface material
that aids in the identication of TP aer promoting a slight
homogeneous pressure on the patient’s skin. ZRPS mapping
extended to all muscles of the dorsal cervical region and
to the muscles adjacent to the thoracic, thoraco-lumbar
and lumbar spine. ZRPS regions with muscle spasms were
considered, or regions where, aer manipulation, the
animal responded with pain-related behavioral changes,
such as grunts, looking at the area, kicking or moving away
from the evaluator, extending from 10 to 30 cm in length.
according to its location (MacGregor & Von Schweinitz,
2006; Rogers, 2012).
Behavior changes are common in patients with TP. Horses
with Girth-Aversion Behavior and TP showed behaviors
such as turning their heads towards the waist area, biting,
beating, kicking, attening their ears, wagging their tail
(Bowenetal., 2017), as well as horses evaluated for ZRPS
identication as described previously (Rogers, 2012). ey
may also be related to shoulder muscle spasms or thoracic
limb ataxia when they have TP in the scapular region, for
example (Pellegrinietal., 2020).
Other instruments, such as algometer or thermography,
may help with the diagnosis of MPS and TP. Although
thermography did not show a strong correlation with focal
TP, it was useful to identify areas of TP with changes in
acupuncture-treated vasomotor tone (Von Schweinitz, 1999).
For the treatment of MPD in horses, the authors
emphasize the importance of correctly identifying TP
in order to implement preventive strategies that aim to
improve sport horses’ comfort, optimize performance
and reduce riding aversion behavior (Bowenetal., 2017).
As described in dogs, the treatment for MPS and TP includes
noninvasive and invasive techniques that can be used alone
or in combination (Ridgway, 1999).
Bowenetal. (2017) observed that as pectoral region TP
were released with stretching, horses improved Girth-Aversion
behaviors. Brockman (2017) described a favorable response
from the combination of massage and acupuncture in
a horse with high exion of the pelvic limbs, showing a
decrease in the frequency and intensity of muscle spasms
and a 50 to 85% improvement in the incidence of high
limb exion that aected the pelvic limb. Laser therapy
has anti-inammatory and analgesic properties and it is
a noninvasive, painless technique that may be associated
with acupuncture (Pellegrinietal., 2020).
e present study observed that from the 6 articles
selected for the equine species, 5 were studies performed
by professionals trained in Traditional Chinese Medicine.
ese data may be related to the fact that acupuncture
professionals participate in the horse rehabilitation process
or also because they are familiar with the occurrence of
TP, since studies have shown that about 70 to 75% of the
points coincide with each other, that is, there is a strong
Figure 2 – Modied from Bowen et al. (2017). Map of the
transverse and ascending pectoral muscles seen
ventrally; frequency and severity of TPs in 38 horses.
Degree of severity correlated with shade of transparent:
light 0-1, light gray: moderate> 1-2, and dark gray:
severe> 2-3.
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Braz J Vet Res Anim Sci. 2020;57(2):e164351
correlation between acupuncture points and TP (Bowenetal.,
2017; Fryetal., 2014; MacGregor & Von Schweinitz, 2006;
Pellegrinietal., 2020; Ridgway, 1999).
e limitation found by the present study was the scarcity
of studies addressing the theme MPS and TP. Although
studies on canine and equine species have shown good
clinical applicability, prospective and randomized studies
are lacking. In addition, the feline species was not addressed,
due to the total scarcity of articles contemplating the
particularities of the species.
Conclusions
In dogs, the occurrence of TP was related to other
comorbidities, assuming a chronic character. For horses, the
occurrence of MPS and TP is linked to poor performance.
Understanding the diagnostic methods, either clinical or
with the aid of instruments, as well as noninvasive and
invasive treatments, is fundamental for professional training.
Overall, the present study suggests further studies are needed
in order to meet the growing demand of professionals
with emphasis on rehabilitation, palliative care or sports
medicine, and thus improve the quality of life of dogs and
horses with MPS and TP.
Conict of Interest
No conict of interest.
Ethics Statement
e present study is a bibliographic review, so there is
no protocol from the ethics committee.
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