Infrared skin temperature measurements for monitoring health in pigs: a review

Table 2 Studies showing relationship between surface (measured by infrared devices) and body temperature in pigs

Source	N	Breed	Size/Age	Surface area(s)	Thermal window (X: yes)	T _ambient [°C]	Correlation (r) ( ^A )	Remarks
Zinn et al. [33]	15	York × Landrace (LR) × Duroc	225 kg	Eyeball	X	N/A	0.14 → 0.51	Before → after parturition. Hairy sites were trimmed.
				Ear (outer side, 5 cm from base)	X		0.12 → 0.39
				Tail head			0.23 → 0.29
				Shoulder			0.18 → 0.47 (*)
				Flank			0.28 → 0.42
				Perineum	X		0.21 → 0.30
				Vulva	X		0.16 → 0.23
				Udder (cranial)	X		0.06 → 0.27
				Udder (middle)	X		0.12 → 0.44
				Udder (caudal)	X		0.13 → 0.39
Loughmiller et al. [2]	24	Crossbred	30 kg	Loin		21 ± 2	0.52 (***)
Warriss et al. [7]	384		~91 kg	Inner side of ear pinna	X^B	21	0.71 (***)	(^C)
Traulsen et al. [32]	42	Crossbred	1st–6th parity	Eyes	X	20.5–24.3	0.33 (*)
				Udder	X		0.41 (*)
				Inner ear	X		0.31 (*)
				Ear base	X		0.32 (*)
				Vulva region (lying)	X		0.49 (*)
				Vulva region (standing)	X		0.32 (*)
Magnani et al. [4]	108		10–17 days	Eye	X	22–30	0.02
				Side, back and womb	X^B		0.02–0.33
				Axilla	X		0.33
Chung et al. [38]	10	Yorkshire × LR (Gnotobiotic)	Piglets	Central abdomen	X	21 ± 1	0.58 (***)
				Central dorsum			0.30 (***)
				Perianal region	X		0.43 (***)
Malmkvist et al. [31]	39	Danish LR × Yorkshire	1st–3rd parity	Snout		15–25	0.21 (**)	(^D)
				Eye	X		0.49 (***)	(^D)
				Udder (caudal third)	X		0.60 (***)	(^D)
Sykes et al. [14]	32	Yorkshire × LR	~85 kg	Vulva (estrus)	X	1.5–25.8	−0.099 to 0.011
Sykes et al. [14]	32	Yorkshire × LR	~85 kg	Vulva (diestrus)	X	1.5–25.8	−0.115 to −0.068
Tabuaciri et al. [39]	485	Large White (LW) × LR, LW × Duroc	<2 kg	Ear base	X	N/A	0.85
				Ear tip			0.27
				Back (crown to rump)			0.75

^AIf only the coefficient of determination (R²) was provided in the article, the magnitude of the correlation (r) between body and IR measured skin temperature was calculated by taking the square root of R². *:P < 0.05, **:P < 0.01, ***:P < 0.001.
^BIndicates measurement sites that are both thermal windows and not thermal windows.
^CTemperature was the mean of the 3 spots of the ear (base, middle, and tip). Body temperature was measured by aiming IR spotmeter on blood on concrete floor, lost from sticking neck vessels.
^DNumbers provided from personal communication.

ISSN: 1751-0147