This article appeared in a journal published by Elsevier. The attached
copy is furnished to the author for internal non-commercial research
and education use, including for instruction at the authors institution
and sharing with colleagues.
Other uses, including reproduction and distribution, or selling or
licensing copies, or posting to personal, institutional or third party
websites are prohibited.
In most cases authors are permitted to post their version of the
article (e.g. in Word or Tex form) to their personal website or
institutional repository. Authors requiring further information
regarding Elsevier’s archiving and manuscript policies are
encouraged to visit:
Author's personal copy
The examination of biophysical parameters of skin
(transepidermal water loss, skin hydration and pH
value) in different body regions of normal cats of
Marcin P Szczepanik PhD*, Piotr M Wilkołek PhD, Łukasz R Adamek MVD,
Zbigniew JH Pomorski PhD
Subdepartment of Clinical
Diagnostics and Veterinary
Dermatology, University of Life
Sciences in Lublin, Gleboka 30,
The purpose of this study was to evaluate transepidermal water loss (TEWL),
skin hydration and skin pH in normal cats. Twenty shorthaired European cats of
both sexes were examined in the study. Measurements were taken from ﬁve
different sites: the lumbar region, the axillary fossa, the inguinal region, the
ventral abdominal region and the left thoracic region. In each of the regions,
TEWL, skin hydration and skin pH were measured. The highest TEWL value
was observed in the axillary fossa (18.22 g/h/m
) and the lowest in the lumbar
region (10.53 g/h/m
). The highest skin hydration was found in the inguinal
region (18.29 CU) and the lowest in the lumbar region (4.62 CU). The highest
skin pH was observed in the inguinal region (6.64) and the lowest in the lumbar
region (6.39). Statistically signiﬁcant differences in TEWL were observed
between the lumbar region and the left side of the thorax region (P¼0.016), the
axillary fossa (P¼0.0004), the ventral region (P¼0.005), and the inguinal region
(P¼0.009). There were signiﬁcant differences in skin hydration between the
lumbar region and the left thorax (P¼0.000003), the axillary fossa (P¼0.002),
the ventral abdomen (P¼0.03), and the inguinal region (P¼0.0003) as well as
between the thorax and the ventral abdomen (P¼0.005). TEWL was higher in
females (15 g/h/m
) than in males (4.57 g/h/m
). Skin hydration was higher in
females (13.89 CU) than in males (12.28 CU). Signiﬁcant differences were not
found between males and females for TEWL and skin hydration. Skin pH was
higher in males (6.94) than in females (6.54), which was signiﬁcant (P¼0.004).
Date accepted: 4 November 2010 Crown Copyright Ó2010 Published by Elsevier Ltd on behalf of
ISFM and AAFP. All rights reserved.
Avariety of measurements of biophysical
parameters, such as transepidermal water
loss (TEWL), skin hydration (corneometry)
and skin pH have recently been used to complement
other methods of examining skin. These methods are
in human medicine and used, among
others, to examine skin in atopic dermatitis,
der to evaluate the effectiveness of locally applied
and in contact dermatitis.
rameters have also been studied in veterinary medi-
cine, most commonly in dogs.
Among the aforementioned parameters, TEWL has
been examined most frequently. TEWL is deﬁned as
outward diffusion of water through the skin into the
comparatively low relative humidity of the
atmosphere. Tewametry measures TEWL and de-
scribes the skin’s ability to retain water. This non-inva-
sive technique is widely held to be a sensitive
indicator of impaired barrier function of the skin
and epidermal damage.
has been observed in people
atopic dermatitis. In atopic dogs there are ultrastruc-
tural changes in the stratum corneum, including ab-
normalities in lipid lamellae organisation and wider
These changes in barrier func-
tion are responsible for increased permeability for en-
vironmental allergens and allow an enhanced
penetration of them, increasing the risk for
Corneometry, the evaluation of skin hydration, is
based on measures of electric capacitance of the stra-
tum corneum and indicates the relative hydration of
*Corresponding author. E-mail: email@example.com
Journal of Feline Medicine and Surgery (2011) 13, 224e230
1098-612X/10/040224+07 $36.00/0 Crown Copyright Ó2010 Published by Elsevier Ltd on behalf of
ISFM and AAFP. All rights reserved.
Author's personal copy
this epidermal layer. This method determines the wa-
ter content of the outer layer of the stratum corneum
at the depth of 10e20 mmto60e100 mm.
A decrease of the value of this parameter has been
conﬁrmed in atopic dermatitis in humans.
Changes in skin pH have been demonstrated in
people, with an increase in pH observed in atopic der-
matitis, seborrheic dermatitis, acne, ichthyosis, contact
dermatitis and Candida albicans infections.
creases in skin pH have also been demonstrated in
dogs with pyoderma.
Multiple factors such as age, sex, breed, and ana-
tomical site inﬂuencing the value of TEWL, skin hy-
dration and skin pH have been examined in dogs as
well as in humans.
With the exception of skin pH,
no studies have in-
vestigated TEWL or skin hydration in cats. The pur-
pose of this study was to examine these biophysical
parameters in normal cats of both sexes in different
Materials and methods
Twenty shorthaired European cats of both sexes
(12 females, including seven spayed, and eight males,
including three castrated), ranging in age from 6
months to 6 years (mean age 26 months) were in-
cluded in the study. The cats were privately owned.
All owners were informed about the details of the ex-
amination and signed permission forms to enrol their
pets in the study. The study was approved by the
University Ethics Commission (resolution number
32/2009 21.04.2009). All cats were given a complete
physical and dermatological examination before tak-
ing the measurements. Only clinically healthy ani-
mals with no history of skin or systemic disease
were included in the study. The animals were accli-
matised in the test room 1 h before the measurements
were taken. The temperature in the room ranged
from 25e28C and the relative humidity from
40e65%. The examination was performed from
March to November 2009. The temperature and rela-
tive humidity were similar to those reported by other
Measurements were taken from ﬁve different sites:
the lumbar region, the left axillary fossa, the right in-
guinal region, the ventral abdominal region and the
left lateral thorax region. In each of the regions,
TEWL, skin hydration and skin pH were measured. Be-
fore the measurement, hair was clipped to 1 mm length
using Metzenbaum scissors. In a study by Watson et al,
clipping did not inﬂuence the results of TEWL.
measurement was taken 2 min after hair clipping, a pe-
riod of time used by other investigators.
For each pa-
rameters six successive measurements were taken and
the mean value was calculated. The assessment of the
parameters was made by means of the Courage
Khazaka Multi Probe Adapter 5 and the appropriate
probes: the Tewameter TM 300 probe (to measure
TEWL), Corneometer CM 825 (to measure skin
hydration), Skin-pH-Meter PH 905 (to measure skin
pH). The same instrumentation was used in previous
studies in dogs.
For all parameters, the mean, standard deviation
(SD) and median were calculated. Statistical analysis
was conducted by the ManneWhitney Utest at
P-values of P¼0.05 (Statistica 6.0 software). For each
parameter, statistically signiﬁcant differences were
calculated between the results obtained in different
regions. Additionally, statistically signiﬁcant differ-
ences between the results for females and males
were calculated, taking into consideration the distri-
bution of parameters in the regions.
For TEWL, the lowest values were observed in the
lumbar region (15.53 g/h/m
), while the highest
values were observed in the axillary fossa (18.22 g/
). TEWL was statistically signiﬁcantly lower in
the lumbar region as compared to the left side of the
thorax region (P¼0.016), the axillary fossa
(P¼0.0004), the ventral region (P¼0.005), and the
inguinal region (P¼0.009) (Table 1,Fig 1).
Table 1. TEWL in different regions in cats.
Lumber region 10.53 10.70 3.05
Thorax 15.06 13.3 8.38
Axillary fossa 18.22 16.30 7.34
Ventral region 15 12.25 7.79
Inguinal region 15.34 13.60 5.73
Fig 1. TEWL in different regions in cats.
225The examination of biophysical parameters of skin
Author's personal copy
TEWL was higher in males (14.57 g/h/m
) than fe-
males (15.00 g/h/m
), but the differences were not
statistically signiﬁcant (P¼0.89). No statistically sig-
niﬁcant differences were observed between males
and females for TEWL in different body regions (lum-
bar region P¼0.97, thorax region P¼0.98, axilla
P¼0.91, ventral region P¼0.06, inguinal region
P¼0.57) (Table 2,Figs 2 and 3).
For skin hydration, the lowest values were observed
in the lumbar region (4.62 CU) and the highest values in
the inguinal region (18.29 CU). The value of this param-
eter was statistically signiﬁcantly lower in the lumbar
region than in the left thoracic region (P¼0.000003),
the axillary fossa (P¼0.002), the ventral abdomen
(P¼0.03), and the inguinal region (P¼0.0003). There
were also statistically signiﬁcant differences between
the results for the left thoracic region and the ventral
abdomen (P¼0.005) (Table 3,Fig 4).
No statistically signiﬁcant differences were ob-
served for the results between males and females for
skin hydration in corresponding body regions
(P¼0.81) (Table 4,Figs 5 and 6). In females, the values
were higher (13.89 CU) than in males (12.28 CU).
Skin pH ranged from 6.39 (the lumbar region) to
6.64 (the inguinal region). Statistically signiﬁcant dif-
ferences in skin pH were observed between the lum-
bar region and the axillary fossa (P¼0.02), and
between the lumbar region and the inguinal region
(P¼0.01) (Table 5 and Fig 7).
The mean skin pH value for males (pH 6.94) was
more basic than the mean female skin pH (pH 6.54)
(P¼0.004). A statistically signiﬁcant difference be-
tween males and females was found for skin pH
from the left thoracic region (P¼0.004) but not for
the ventral abdomen (P¼0.09), the lumbar region
(P¼0.39), the axilla (P¼0.18) or the inguinal region
(P¼0.49) (Figs 8 and 9).
TEWL, skin hydration and skin pH measurements are
considered to be useful techniques to assess the dam-
age of skin in humans and are widely used to evaluate
skin barrier function in patients with atopic dermatitis
as well as to evaluate the therapeutic efﬁcacy of
locally administered treatments.
The integrity of skin barrier function is important in
the aetiopathogenesis of atopic dermatitis. In dogs
with atopic dermatitis, there are numerous defects in
Table 2. TEWL in male and female cats.
Males 14.57650 12.80000 49.50281
Females 15.00100 12.70000 50.60481
Table 3. Skin hydration in different regions in cats.
Lumber region 4.62421 3.87000 4.35559
Thorax 14.18632 9.62000 15.02929
Axillary fossa 15.44421 13.08000 9.57414
Ventral region 13.38263 13.10000 7.51884
Inguinal region 18.29350 14.11500 10.75044
Fig 2. TEWL in different regions in male cats.
Fig 3. TEWL in different regions in female cats.
226 MP Szczepanik et al
Author's personal copy
skin barrier function. Marsella et al found ultrastruc-
tural changes in the epidermis in such animals.
Atopic dogs have abnormalities in lipid lamellae orga-
nisation and wider intracellular species containing ab-
normal lipid material.
Lamellar lipids are reduced in
number and highly disorganised.
Lipid lamella are
also markedly heterogenous compared to normal
It is hypothesised that these defects are re-
sponsible for enhanced penetration of environmental
allergens and increased risk of sensitisation in predis-
Reiter et al and Pin et al also ob-
served a decrease in the amount of ceramides in the
skin in atopic dogs.
Ceramides are the largest
group of stratum corneum lipids. A ceramide deﬁ-
ciency is associated with an increase in TEWL and
may be involved in impaired skin barrier function.
In veterinary medicine, information regarding these
biophysical parameters in different diseases is lim-
There is also little information concerning
the baseline values of these parameters in different an-
imal species with most information obtained from ca-
nine studies. With the exception of pH, TEWL and
skin hydration have not been investigated in cats.
Research conducted by other authors has pointed to
statistically signiﬁcant differences in the case of TEWL
between different dog breeds. Hestler et al determined
that TEWL values differ signiﬁcantly between Beagles
and Basset Hounds.
Differences in TEWL between
breeds have also been described by Young et al.
TEWL may vary in different body regions in people
Oh and Oh found that TEWL in Beagles is
the lowest for ear pinnae and for the lumbar region, as
compared to other body regions,
with the highest
values found on the head and the tail. Yoshihara et al,
who also took measurements with Tewameter TM
300, showed that the lowest values of TEWL are found
in the lumbar region.
A similar relationship was
found in the present study, in that TEWL was lowest
in the lumbar region, which was statistically
Fig 4. Skin hydration in different regions in cats.
Table 4. Skin hydration in male and female cats.
Mean Median SD
Males 12.28436 9.930000 9.04522
Females 13.89281 9.720000 12.05099
corneometry - ma
Fig 5. Skin hydration in different regions in male cats.
corneometry - female
Fig 6. Skin hydration in different regions in female cats.
227The examination of biophysical parameters of skin
Author's personal copy
signiﬁcantly different from values obtained for other re-
gions. In contrast, Watson et al, determined that the
lowest TEWL values were found in the ventrum in
Previous studies regarding values of this pa-
rameter have not been conducted in cats, therefore, a di-
rect comparison of results in the present investigation
and other studies cannot be made.
The inﬂuence of body region on skin pH in animals
was investigated by Meyer et al
In this investigation,
various animal species (cattle, horses, goat, sheep), in-
cluding dogs of different breeds and cats were stud-
ied. They concluded that there were no statistically
signiﬁcant differences in skin pH of different body re-
gions. This is in contrast with the results of the present
study. Similarly, research in humans has shown that
pH values vary according to site.
the values of skin pH, Mayer et al concluded that skin
pH obtained from most sites in cats was slightly acidic
at 5.94e6.81, as compared to the results in the present
study of 6.39e6.64.
Young et al assessed the inﬂuence of sex on TEWL,
skin hydration, and skin pH
in Beagles, Fox Terriers,
Labrador Retrievers and Manchester Terriers. In this
study, the sex did not signiﬁcantly inﬂuence the
parameters, although males exhibited a larger range
in skin pH than females.
These results correlate with
the results obtained in the present study in regards to
TEWL and the hydration of the epidermis. However,
in the present study a signiﬁcant difference in skin pH
between males and females was observed (6.94 in
males, 6.54 in females). The inﬂuence of sex on skin
pH was also examined by Mayer et al and Bourdeau
These authors also failed to observe any inﬂu-
ence of sex on skin pH in cats, but in cattle, the pH
values of males were more basic than in females.
Table 5. Skin pH in different regions in cats.
Mean (pH) Median SD
Lumber region 6.394000 6.340000 0.281395
Thorax 6.570000 6.480000 0.354933
Axillary fossa 6.628500 6.625000 0.452842
Ventral region 6.553684 6.460000 0.443123
Inguinal region 6.643158 6.600000 0.509826
Fig 7. Skin pH in different regions in cats.
Fig 8. Skin pH in male and female cats.
M - r a b m u L
F - r a b m u L
M - x a r o h T
F - x a r o h T
M - a l l i x A
F - a l l i x A
M - l a r t n e V
F - l a r t n e V
M - l a n i u g n I
F - l a n i u g n I
Fig 9. The distribution of skin pH in different regions for
male and female cats.
228 MP Szczepanik et al
Author's personal copy
Matousek and Campbell also found that male dogs had
a more basic pH than females in dogs.
We anticipate that the assessment of biophysical pa-
rameters of skin, especially TEWL, will be useful in
understanding atopic dermatitis in cats. Much re-
mains to be known about atopic dermatitis in cats,
and the diagnosis of this disease can be challenging.
The diagnosis is made on the basis of historical and
clinical features and immunological tests (positive
skin tests or increase of speciﬁc IgE) and the exclusion
of other skin diseases which exhibit similar clinical
In dogs, it is known that there are differences
in TEWL in non-lesional skin between healthy dogs
and dogs with atopy, with an increase in TEWL in
atopic dogs. It is possible that such a relationship in
cats exists, and disturbances in biophysical para-
meters of skin may be useful tools in the early diagno-
sis of atopy in this species.
The knowledge of skin pH in cats may also be use-
ful in topical therapy. It is known that in dogs a in-
crease of pH is found in pyoderma.
In dogs the
use of topical products containing ethyl lactate, ben-
zoyl peroxide, chlorhexidine, calicic acid, and sulfur
causes a normalisation in skin pH, and it is possible
to shorten the duration of topical therapy by using
agents with pH similar to dogs skin.
In cats, similar to dogs and humans, there are dif-
ferences between body regions in biophysical param-
eters of skin. Further research is necessary in order to
specify the range of values of the biophysical para-
meters in healthy cats, and to assess them in various
The authors thank Wiesław Sitkowski for statistical
1. Fluhr JW, Feingold KR, Elias PM. Transepidermal water
loss reﬂects permeability barier status: validation in
human and rodent in vivo and ex vivo models. Exp
Dermatol 2006; 15: 483e92.
2. Dirschka T, Tronnier H, Fo R, Holst L. Clinical and labo-
ratory investigations of epithelial barrier function and
atopic diathesis in rosacea and perioral dermatitis. Br J
Dermatol 2004; 150: 1136e41.
3. Gupta J, Grube E, Ericksen MB, et al. Intrinsically defec-
tive skin barrier function in children with atopic derma-
titis correlates with disease severity. J Allergy Clin
Immunol 2008; 121: 725e30.
¨nig B, Scha
¨fer T, Huss-Marp J, et al. Skin sur-
face pH, stratum corneum hydration, trans-epidermal
water loss and skin roughness related to atopic eczema
and skin dryness in a population of primary school
children: clinical report. Acta Derm Venereol188e91.
5. Rudolph R, Kownatzki E. Corneometric, sebumetric and
TEWL measurements following the cleaning of atopic
skin with a urea emulsion versus a detergent cleanser.
Contact Derm 2004; 50: 354e8.
6. Suk-Jin Choi, Min-Gyu Song, Whan-Tae Sung, et al. Com-
parison of transepidermal water loss, capacitance and pH
values in the skin between intrinsic and extrinsic atopic
dermatitis patients. J Korean Med Sci 2003; 18:93e6.
7. Lofﬂer H, Steffes A, Happle R, Effendy I. Allergy and ir-
ritation: an adverse association in patients with atopic
eczema. Acta Derm Venereol 2003; 83: 328e31.
8. Biro K, Thac¸ i D, Ochsendorf FR, Kaufmann R, Boehncke
WH. Efﬁcacy of dexpanthenol in skin protection against
irritation: a double-blind, placebo-controlled study. Con-
tact Derm 2003; 49:80e4.
9. Aschoff R, Schwanebeck U, Bra
¨utigam M, Meurer M. Skin
physiological parameters conﬁrm the therapeutic efﬁcacy
of pimecrolimus cream 1% in patients with mild-to-mod-
erate atopic dermatitis. Exp Dermatol 2009; 18:24e9.
nska H, Reduta T, Szmitkowska D. Evaluation of
skin barrier function in allergic contact dermatitis and
atopic dermatitis using method of the continuous
TEWL measurement. Ann Acad Med Bialost 2003; 48:
11. Oh W-S, Oh T-H. Measurement of transepidermal water
loss from clipped and unclipped anatomical sites on the
dog. Aust Vet J 2009; 87:409e12.
12. Shimada K, Yoshihara T, Yamamoto M, et al. Transepi-
dermal water loss (TEWL) reﬂects skin barrier function
of dogs. J Vet Med Sci 2008; 70: 841e3.
13. Bourdeau P, Taylor KW, Nguyen P, Biourge V. Evalua-
tion of the inﬂuence of sex, diet and time on skin pH
and surface lipids of cats. Vet Dermatol 2004; 15(suppl
14. Matousek J, Campbell KLA. Comparative review of
cutaneous pH. Vet Dermatol 2002; 13: 293e300.
15. Young LA, Dodge JC, Guest KJ, Cline JL, Kerr WW. Age,
breed, sex and period effects on skin biophysical param-
eters for dogs fed canned dog food. J Nutr 2002; 132:
16. Hester SL, Rees CA, Kennis RA, et al. Evaluation of cor-
neometry (skin hydration) and transepidermal water-
loss measurements in two canine breeds. J Nutr 2004;
17. Watson A, Fray T, Clarke S, Yates D, Markwell P. Reliable
use of the ServoMed Evaporimeter EP-2 to assess trans-
epidermal water loss in the canine. J Nutr 2002; 132:
18. Yoshihara T, Shimada K, Momoi Y, Konno K, Iwasaki T.
A new method of measuring transepidermal water loss
(TEWL) of dogs skin. J Vet Med Sci 2007; 69: 289e92.
19. Yoshihara T, Endo K, Konno K, Iwasaki T. A new
method for measuring canine transepidermal water
loss. Vet Dermatol 2004; 15: 39.
20. Beco L, Fontaine J. Corneometry and transepidermal wa-
ter loss measurements in the canine species: validation
of these techniques in normal beagle dogs [Corneometrie
et perte d’eau transepidermique: validation des tech-
nique chez des chiens sains]. Ann Med Vet 2000; 144:
21. Shimada K, Yoshihara T, Konno K, Nishifuji K. Increase
in transepidermal water loss and decrease in ceramide
content in the lesional and non-lesional skin of canine
atopic dermatitis. Vet Dermatol 2009; 20: 541e6.
22. Hightower K, Marsella R, Flynn-Lurie A. Effects of age
and allergen exposure on transepidermal water loss in
house dust mite-sensitized beagle model of atopic der-
matitis. Vet Dermatol 2010; 21:89
23. Shah JH, Zhai H, Maibach HI. Comparative evaporimetry
in man. Skin Res Technol 2005; 11:205e8.
229The examination of biophysical parameters of skin
Author's personal copy
24. Marsella R, Samuelson D, Doerr K. Transmission elec-
tron microscopy studies in an experimental model of ca-
nine atopic dermatitis. Vet Dermatol 2010; 21:81e8.
25. Schmid-Wendtner MH, Korting HC. The pH of the skin
surface and its impact on the barrier function. Skin Phar-
macol Physiol 2006; 19: 296e302.
26. Popiel J, Nicpo
n J. Relacje pomie
˛dzy ph sko
´ry w prze-
biegu pyoderm u pso
´w przed i po zastosowaniu prepar-
˛trznie. Acta Sci Pol Medicina
Veterinaria 2004; 3:53e60.
27. Marrakchi S, Maibach HI. Biophysical parameters of
skin: map of human face, regional, and age-related dif-
ferences. Contact Derm 2007; 57:28e34.
28. Mayer W, Neurad K. Comparison of skin pH in domesticated
and laboratory mammals. Arch Dermatol Res 1991; 283:16e8.
29. Piekutowska A, Pin D, Re
`me CA, Gatto H, Haftek M. Ef-
fects of a topically applied preparation epidermal lipids
on the stratum corneum barrier of atopic dogs. J Comp
Path 2008; 138: 197e203.
30. Inman AO, Olivry T, Dunston SM, Monteiro-Riviere NA,
Gatto H. Electron microscopic observations of stratum
corneum intercellular lipids in normal and atopic dogs.
Vet Pathol 2001; 38: 720e3.
31. Reiter LV, Torres SMF, Wertz PW. Characterization and
quantiﬁcation of ceramides in non-lesional skin of ca-
nine patient with atopic dermatitis compare with con-
trols. Vet Dermatol 2009; 20: 260e6.
32. Pin D, Popa I, Piekutowska A, et al. Biochemical analysis
of epidermal lipids in normal and atopic dogs, before
and after administration of an oral omega-6/omega-3
fatty acid supplement (Megaderm). Vet Dermatol 2008;
19(suppl 1): 68. [abstract].
33. Scott DW, Miler HW, Grifﬁn CE. Small animal dermatol-
ogy. 6th edn. Philadelphia: WB Saunders, 2001.
vailable online at www.sciencedirect.com
230 MP Szczepanik et al