"I AM," James Herriot says, "as soppy over my dogs as any old lady." A trait which, he assures us, "has always stood me in good stead in my dealings with clients." But he's not "soppy." Not a bit.

It was Herriot's love of dogs that first persuaded him to become a vet, back in a time when there were no small animal practices and large animal practices were shrinking with their mainstay -- the draft horse. Herriot's education, before he entered the Glasgow Veterinary College, was classical -- no science at all -- and perhaps that explains the grace of his prose in the series of books that begins with All Things Bright and Beautiful.

Now, in his twilight years, James Herriot returns to the animal that first inspired him and gives us, James Herriot's Dog Stores, a collection of 50 tales, several never before published in the United States. Some of the tales made me laugh out loud, some cut very close to the bone.

Dog stories tend to be interesting about dogs or interesting about men, rarely both. Either dogs or men are cartoons. Jack London's White Fang is a wonderful character, but his masters have all the depth of the Hardy Boys. Richard Adam's Plague Dogs are brilliantly drawn, his human characters less so. Mark Twain's dog, Aileen Mavoureen, and Thomas Hardy's Mongrel tell us more about their authors than about dogs. And, at the risk of outraging everybody's childhood memories, Albert Payson Terhune's dogs and men are both rather silly.

James Herriot writes about that place where two unalike species, Canis familiaris and Homo sapiens, encounter each other. "I could never take dogs for granted. Why were they so devoted to the human race? Why should they delight in our company and welcome us home in transports of joy? Why should their greatest pleasure be in being with us in our homes and wherever we were?"

More frequently than we think, dogs change men. Herriot tells about Wes, a boy from the roughest sort of home -- a boy destined to go bad. Wes finds courage, hope and even decency caring for his sick mongrel, Duke. Then there's Theo -- the jaunty pub terrier -- and his owner: witty, careless Paul whose "attractive casualness, the nonchalant good manners -- they all had their roots in the fact that nothing touched him very deeply." But nonchalance can conceal other, darker emotions, as Herriot learns when the dog, Theo, is diagnosed incurable.

And men can change dogs. Roy was chained up in a dark hovel for months. His "hindquarters were a welter of pressure sores which had turned gangrenous, and strips of sloughing tissue hung down from them. There were similar sores along the sternum and ribs. The coat, which seemed to be a dull yellow, was matted and caked with dirt." The Widow Donovan with her quack nostrums and kind heart adopts Roy and later with the magnificent Golden Retriever at her side, we share her pride as she says, almost fiercely, "Mr. Herriot, haven't I made a difference to this dog?"

Herriot reserves his anger for the dog abandoners, "Some time ago, the humans he had loved and trusted had opened the car door, hauled him out into an unknown world and driven merrily away. I began to feel sick -- physically sick -- and a murderous rage flowed through me. Had they laughed, I wondered, these people, at the idea of the bewildered little creature toiling vainly along behind them?" But for every human who abuses dogs and violates their trust, there's another, like Sister Rose, a soldier in "the selfless army which battle(s) ceaselessly and untiringly on the side of the great throng of dependent animals."

JAMES HERRIOT is one of the most widely read writers in our language. I don't know how many times some country person has shamefacedly confessed to me, "Oh, I don't get time to read much. Except for James Herriot. I've read all of him." I find Herriot's popularity encouraging.

Most of these dogs are light and charming. There's Tricky-Woo, the pampered pet who just wanted to be a real dog, and Cedric, the comically unaware, flatulent Boxer.

Some of these stories: "Have a Cigar," "Jock" and "Amber" are classics that will anthologized and reread so long as men and dogs love each other.

One of the questions Herriot addresses is the fear old people have for their pets. Who will care for them when they cannot? Do dogs have souls? The gallant Miss Stubbs knows she is dying, "You see, I know I'll be reunited with my brothers, but . . . but . . ."

"Well, why not with your animals?" Herriot asks.

" 'That's just it.' She rocked her head on the pillow and for the first time I saw tears on her cheeks. 'They say animals have no souls.'

" 'Who says?'

" 'Oh, I've read it and I know a lot of religious people believe it.'

" 'Well, I don't believe it.' I patted the hand which still grasped mine. 'If having a soul means being able to feel love and loyalty and gratitude, then animals are better off than a lot of humans. You've nothing to worry about there.'

" 'Oh, I hope you're right. Sometimes I lie at night, thinking about it.'

" 'I know I'm right, Miss Stubbs, and don't you argue with me. They teach us vets all about animals souls.' "

I suppose there's some who will find this "soppy." Me, I think it's true.