
These are some notes that the Tax Office use:
http://webarchive.nationalarchives.gov.uk/20100512173947/http://www.hmrc.gov.uk/bens/ben14.htm"Breeding economics
The principal factors which determine the possible income generated from any breeding unit are basically similar and can be summarised as follows.
Breeding capability of female
Average size of litter or batch of eggs
Length of gestation
Average maturity rate, which is age at which offspring become independent.
The young, of course, are not sold or ready to leave the breeder as soon as they are born. The breeder has the task of nurturing the young until they are mature. During this delicate period the breeder will incur
cost of feeding, and special dietary requirements
veterinary bills for examinations, treatments, vaccinations and so on
heating and bedding costs
cost of nursing and possible additional staff costs.
Once the litter or fledglings have reached maturity, the breeder may then also incur costs of any pedigree registration and advertising.
This expenditure will be in addition to the normal maintenance and feed expenditure incurred in the breeding establishment, which typically will include most of the following.
Operating expenditure and associated costs
Cost of new stock
Stud fees
Food costs
Heating costs
Maintenance to accommodation
Staff wages
Transportation costs - attending shows and so on.
Miscellaneous small equipment and consumables
Sterilising fluids/disinfectants
Bedding - ordinary and special bedding for welping
Printing stationery and advertising
Miscellaneous equipment such as bowls, brushes, towels, bins, collar, leads, and so on.
Fees and subscriptions
Breeding licence fees
Veterinary fees
Show/exhibition or other competition fees
Journals and other breed circulations
Registration fees - Clubs, Societies or Associations, for example, registration of puppy with the Kennel Club.
In considering the level of bona fide business expenditure relating to the establishment, a common problem revolves around the head count of productive animals. That is, animals which are actively used for breeding or showing, or are in any other way essential to and make an active contribution to the establishment.
A substantial number of breeders, especially in the dog world, become very attached to members of their stock and contrary to good business practise may continue to keep and maintain animals that have become non-productive. They, in essence, revert strictly to the status of `pet' rather than a business asset.
Ascertaining the true position appertaining to business stock or private pet, in the majority of cases will not be clear cut and where relevant will require careful consideration of the facts in each individual case.
Hobby or business
Most people involved with breeding, whether it be dogs, cats, pigeons and so on, take their activities seriously. This is not to say, however, that they also take the commercial side of breeding seriously or are motivated by a prime objective to make profits. As is often the case, the process of selective breeding can be a slow and costly exercise. The breeder will retain young that show promise. These will, in turn, depending on their eventual quality, be bred from, further enhancing the blood line and so the process will continue.
Inevitably, the creation of a blood line will result in a gradual increase in stock of animals and ensuing costs. Depending on the success of the breeder, demand should also increase, for use of stud animals or for young stock, thereby increasing the potential for profit.
It must be said, however, that this is not always a natural progression and even if success is eventually achieved, the time scale can be variable. A breeder may have to support a growing establishment, with no realistic prospect of enjoying an equally good inflow of receipts, for the foreseeable future.
The breeder may, of course, have been content to subsidise his/her interest and enthusiasm, but as costs increase, may be forced to consider one of two options.
To trim down stock of animals, selling off stock to other breeders or as pets
Increasing breeding activities in order to raise the required flow of receipts by selling young into the pet market.
Depending on individual circumstances, such additional breeding purely to increase income may become a permanent feature or be undertaken at different times, either to cover expenditure peaks, fund capital expenditure and so on.
Whether the activities amount to the carrying on of a trade profession or vocation so that the profits are assessable under Cases I or II of Schedule D or is merely a hobby, is a question that can only be determined on consideration of the relevant facts in individual cases. "
So yes I'd certainly say that keeping a bitch to only the end of her breeding life at say 7 will outweigh any excess income over rearing etc costs of her litters.