Table 1.

Dietary strategies for stress alleviation in cats and dogs.

Active Ingredients	Resources	Mechanism	Species	Dosage	Measurements	Supportive/Negative	Reference
Gallic acid	Fruits, vegetables, and medicinal plants	Antioxidants; intestinal health	Dog	500 mg/kg	SOD and CAT ↑; TNF- α ↓; IL-1 β ↓; diarrhea rate ↓; SCFAs-producing bacteria ↑; serum cortisol and HSP70 ↓	Regulate intestinal flora to alleviate oxidative stress and inflammatory reaction	[32]
Tannic acid	Gallnut	Antioxidants; intestinal health	Dog	2.5 g/kg	Serum COR ↓; GC ↓; ACTH ↓; HSP70 ↓; beneficial bacteria ↑; pathogenic bacteria ↓; fecal butyrate ↑	Regulate intestinal flora to alleviate stress injury	[106]
Pinus taeda hydrolyzed lignin (PTHL)	P. taeda (tree)	Antioxidants	Dog	/	SOD, CAT, and GPx activity ↑	Antioxidation	[107]
Curcumin	Curcuma longa	Antioxidants	Dog	32.9 mg/kg	ROS ↓; CAT, SOD and GPx ↑; total antioxidant capacity ↑; lymphocytes and globulin levels ↓	Enhance antioxidant capacity and alleviate inflammatory reaction	[108]
A blend of essential oils and vitamin E	Essential oils (cloves, rosemary, and oregano)	Antioxidants	Dog	/	Non-protein self-sustaining group ↑; glutamate S-transfer ↑; ROS ↓	Antioxidation	[109]
Vitamin E	Commercial sources	Antioxidants	Dog	500 mg	Prevent the decrease in PON1 activity and EMF, and the increase in plasma MDA.	Alleviate oxidative stress	[110]
Vitamin C	Commercial sources	Antioxidants	Dog	/	SOD, GPx, and CAT ↑;	Antioxidation	[111]
			Dog/cat	/	ROS ↓; improve the blood flow distribution, promote the synthesis of catalamine and arginine vasopressin, regulate immunity, and inhibit the activity of cytotoxic T cells	Relieve the damage caused by oxidative stress and inflammatory reaction	[112]
VE and VC and beta-carotene	Commercial sources	Antioxidants	Cat	VE: 742 mg/kg; VC: 84 mg/kg; beta-carotene: 2.1 mg/kg	Serum 8-OHdG ↓	Reduce DNA oxidative damage	[113]
Selenium	Selenium yeast	Antioxidants	Dog	0.3 mg/kg	MDA ↓; GPx, SOD, and CAT ↑	Antioxidation	[114]
Radioiodine	Commercial sources	Antioxidants	Cat	/	Urinary free 8-isoprotenates ↓	Alleviate lipid peroxidation	[115]
Saccharomyces cerevisiae fermentation product	S. cerevisiae fermentation	Antioxidants	Dog	0.13%	Serum MDA and 8-isoprotenates ↑; the expression of blood COX-2 and MPO mRNA ↓	Inhibit innate immune activation to alleviate inflammation	[116]
Fish-oil-based foods	Commercial sources	Antioxidants	Dog	/	GPx and CAT activity ↑; blood glucose and total and LDL cholesterol ↓	Antioxidation and reduce blood sugar and blood lipid	[117]
Melatonin	Commercial sources	Antioxidants	Dog	0.3 mg/kg	Serum SOD, GPX, and CAT ↑; MDA ↓	Enhance antioxidant capacity to relieve oxidative damage	[118]
α-casozepine	A tryptic bovine αs1-casein hydrolysate	Anxiolytic agents	Dog	/	Anxiety behavior ↓; serum cortisol ↓	Relieve anxiety and improve behavior; reduce stress hormone secretion	[119]
			Dog	Closely 15 mg/kg BW	Score of emotional disorder evaluation in dogs ↓;	Relieve anxiety and improve behavior	[120]
			Cat	15 mg/kg BW	anxiety score ↓; different items (fear of strangers, contact with familiars, general fears, fear-related aggressions, and autonomic disorders) ↓	Relieve anxiety and improve behavior	[121]
α-casozepine and tryptophan	Commercial diet	Anxiolytic agents	Cat	α-casozepine: 15 mg/kg; tryptophan: 3.6 g/kg DM	The ratio of plasma tryptophan to large neutral amino acids ↑; urinary cortisol ↓	Promote tryptophan utilization and reduce stress hormone secretion	[122]
			Cat	/	The duration of cat inactivity decreases when placed in unfamiliar positions	Relieve anxiety and improve behavior	[123]
Tryptophan	Commercial sources	Anxiolytic agents	Dog	5.7 g/kg DM	Plasma Trp ↑; Trp/(large neutral amino acids) ↑	Promote tryptophan utilization; the impact on anxiety and behavior remains to be determined	[124]
			Dog	Trp: LNAA = 0.075:1	Serum serotonin ↑; improved stool scores	Relieve anxiety and reduce diarrhea	[125]
			Dog	Add extra 1.45 g/kg	Attacks related to territorial domination ↓	Reduce the stress of territorial competition	[126]
			Dog	/	Stress-related abnormal behavior ↓	Relieve anxiety and improve behavior	[127]
L-theanine	Commercial sources	Anxiolytic agents	Dog	50 mg (less than 10 kg), 100 mg (10–25 kg), 200 mg (more than 25 kg)/day	Anxiety scores ↓; drooling, following people, pacing, panting, and hiding ↓	Relieve anxiety and improve behavior	[128]
			Dog	50 mg (less than 10 kg), 100 mg (more than 10 kg)/day	Interactive behavior ↑	Relieve anxiety and improve behavior	[129]
			Cat	50 mg/day	Stress score ↓; inappropriate urination/defecation, fear-induced aggressiveness, hypervigilance/tenseness, or physical/functional manifestations of stress ↓	Relieve anxiety and improve behavior	[130]
Medium chain triglyceride diet	Commercial diet	Anxiolytic agents	Dog	5.5%	ADHD-related anxiety behavior ↓	Relieve anxiety and improve behavior	[131]
Medium chain triglyceride and Brain Protection Blend (BPB)	BPB including B vitamins, antioxidants, omega-3 fat acids, and arginine	Anxiolytic agents	Dog	6%/9%	Blood DHA, EPA, total omega-3 PUFAs, and omega-3/omega-6 ratio ↑; symptoms of cognitive dysfunction syndrome ↓	Promote brain health and improve behavior	[132]
Fish hydrolysate and melon juice concentrate	Commercial sources	Anxiolytic agents	Dog	F: 500 mg, M: 11 mg; double (BW more than 10 kg)	Interactive behavior ↑; stress behavior ↓	Relieve anxiety and improve behavior	[133]
Lemon balm, fish peptides, oligofructose, and L-tryptophan	Commercial diet	Anxiolytic agents	Cat	L: 0.1%; F: 0.1%; O: 0.5%; Trp: 0.08%	Average 24 h urinary cortisol/creatinine ratio ↓	Reduce stress hormone secretion	[134]
Bacillus amyloliquefaciens CECT 5940	Commercial bacteria	Intestinal Health	Dog	1 × 106 CFU/g DM	The bacillus ↑; the coliforms ↓	Regulate intestinal flora	[135]
Polyphenols and omega-3 fatty acids	Fish oil and a polyphenol blend (citrus pulp, carrot, and spinach)	Intestinal Health; anxiolytic agents	Dog	/	Plasma 4-EPS ↓; anxiety-related metabolites ↓; Blautia, Parabacteroides, and Odoribacter ↑	Regulate intestinal flora to relieve anxiety	[136]
S. boulardii	Commercial bacteria	Intestinal Health	Dog	1 × 109 CFU di/kg of feed	Fecal calprotectin ↓; IgA ↓; fecal cortisol ↓	Reduce intestinal inflammation and stress hormone secretion	[137]
A fiber–prebiotic–probiotic blend	Commercial sources	Intestinal Health	Dog	/	Fecal score ↓; blood lipid ↓; fecal IgA ↑	Enhance intestinal immunity and improve stool quality	[138]
Enterococcus faecium SF68	Commercial bacteria	Intestinal Health	Cat/Dog	2.1 × 109 CFU/day	Diarrhea rate ↓	Reduce diarrhea	[139]

↑, increase; ↓, reduction; IgA, immunoglobulin A; NO, nitric oxide; COR, cortisol; GC, glucocorticoid; ACTH, adrenocorticotropic hormone; HSP70, heat shock protein 70; SOD, superoxide dismutase; CAT, catalase; GST, glutathione-S-transferase; GPx, glutathione peroxidase; ADHD, attention-deficit/hyperactivity disorder; ROS, reactive oxygen species; GSH, reduced glutathione; MDA, malondialdehyde; PON1, paraoxonase-1; EMF, erythrocyte membrane fluid; 4-EPS, 4-ethylphenyl sulfate; PUFA, polyunsaturated fatty acids; COX-2, cyclooxygenase-2; MPO, myeloperoxidase; LNAA, large neutral amino acids; Trp, tryptophan.