Table 2.

Characteristics of studies evaluating vegan diets in dogs.

Author	Signalment	Study Design	Sample Size	Diet Type	Duration of Feeding Diet	Comparator	Outcomes Assessed
Animal—Based Outcomes
Brown et al., 2009 [32]	Pure-bred Siberian huskies Racing sled dogs Age not stated	Non-randomized experimental trial	12	Meat-free diet	16 weeks	Compared a commercial meat-based diet with an experimental meat-free	Food intake Body weight Complete blood count
Cavanaugh et al., 2021 [33]	PB diet Median age = 2.9 years Median BW = 19.5 kg Mixed breed: 27 Siberian husky: 2 Pitbull: 2 Border collie: 1 Vizsla: 2 Pug: 1 Spayed females: 16 Castrated males: 1 Intact female and male: 1 Control diet: Median age = 3.8 years Median BW = 20.8 kg All mixed breed and spayed females and males	Non-randomized experimental study	PB = 34 Control = 4	Commercial plant-based diet Control diet (traditional dry commercial diet)	12 weeks 4 weeks wash in period	Compared to a traditional dry commercial diet	Clinical sign Biochemical profile Plasma amino acid panel Taurine Urinalysis Echocardiography Guardian-based acceptance
Cavanaugh et al., 2022 [34]	Adult mixed-breed dogs G1 and G2 average age = 3 and 2.8 years, respectively G1 and G2 average weight = 14.3 and 14.8 kg, respectively	Randomized controlled trial	16	Commercial extruded plant-based diet	4 weeks	Compared to commercial extruded traditional diet	Physical examination Blood analysis for TMOA, choline, betaine, and creatine
El-Wahab et al., 2021 [35]	Healthy female Beagle Average BW = 11.0 ± 1.31 kg Average age = 3 years	Experimental crossover design	8	Vegetarian basic diet Vegetarian basic diet with hydrolyzed feather meal and either corn meal, fermented rye or rye supplemented	10 days	N/A	Food and water intake Body weight Fecal score Digestibility
Ingenpaß et al., 2021 [36]	Unneutered female Beagle dogs Average BW = 9.64 ± 0.68 kg Average BCS = 4.98	Experimental crossover design	6 (n = 3 per diet)	Vegetarian diet containing wheat gluten (8.81%), rice protein (8.81%), sunflower oil (6.84%) and vitamin D3 (0.045 g/kg)	24 days	Compared to meat-based diet containing poultry meal (19.5%) and poultry fat (5.23%)	Fecal quality Apparent digestibility Crude protein Crude fat Nitrogen estimation
Kiemer 2020 [37]	Average age = 2.15 years Whippet, Golden retriever, mixed, Australian mini shepherd, cocker-mixed, German shepherd cross, Husky, Boston terrier, Daschund, Cavalier king Charles spaniel, French bulldog, Corgi	Randomized controlled trial	PB diet = 20 Control = 20 Feeding trial = 8 (vegan = 4, control = 4)	100% vegan diet for at least 3 months before the trial	6 weeks	Compared to meat-based diet	Blood chemistry Physical examination Guardian survey
Semp 2014 [27]	Not stated	Cross-sectional	20	Commercial plant-based pet food 27% supplemented diet 65% no supplemented diet	Average length of diet consumption: 2.83 years	N/A	Clinical examination Body condition score Blood hematology/biochemistry Pancreatic parameters Magnesium Calcium Total protein Folic acid Vitamin B12 Carnitine
Rankovic et al., 2020 [38]	Siberian husky Male neutered (n = 4) Female spayed (n = 5) Female intact = 2 Average age = 5.63 ± 0.57 Average BCS = 4.80 ± 0.66 Average BW = 24.94 ± 0.99 kg	Experimental crossover design	Study 1 = 6 Study 2 = 11	Three starch rich foods: white bread, cooked white long grain rice, and cooked Eston green lentils	150 min	Four commercial foods	Glycemic index Glycemic response Insulinemic response
Richards et al., 2021 [39]	Adult, client-owned Siberian huskies Neutered males = 4 Spayed females = 5 Intact females = 1 Average age = 5.63 ± 0.72 years Mean BW = 23.32 ± 1.15 kg	Non-randomized experimental	11	Vegetarian formula	Experimental day and 7 weeks wash out period	Four commercial foods	Gastric emptying
Guardian—Reported Outcomes
Dodd et al., 2022 [40]	Average age = 6 years 679 males 688 females MB diet = 665 PB diet = 357 118 specific breeds 162 crossbreds	Qualitative research	1189	Plant-based diet	9 months	Responses were compared to those of guardians feeding meat-based diets and to a combination of both	Guardian perception of health and wellbeing BCS Lifespan (previously owned dogs)
Knight and Satchell 2021 [26] *	Females 82%	Survey	2639 dogs (4057 guardians of dogs and/or cats)	Vegan	Mixed survey	Conventional diet Raw meat diet Mixture	Guardian -reported palatability
Knight et al., 2022 [41] *	Fed a conventional meat diet (54%) Raw meat diet (33%) Vegan diet (13%) Vegan diet animals with health disorders (36%)	Cross sectional survey	2639 dogs	Vegan diet	At least 1 year	Comparison between the three types of diets (meat, raw meat, and vegan)	Veterinary visits Medication use Guardian based health Seven general health disorders 22 specific health disorders
Semp 2014 [27]	M,F Not stated	Cross-sectional survey	38 guardians 174 dogs	Commercial plant-based pet food 27% supplemented diet 65% no supplemented diet	Average length of diet consumption: 2.83 years	N/A	Guardian-reported health Stool consistency Coat condition

BCS: body condition score; BW: body weight; MF: male, female; MB: meat-based diet; PB: plant-based diet. * These studies relate to the same survey dataset with different outcomes presented in the two studies.