Q: I have a TB mare who has nice conformation and a good temperament, but unfortunately, went unsound around the age of eight which we eventually worked out was due to navicular disease; she was trialled but unraced and I competed her at low-level eventing and show jumping before retiring her as a paddock mate. I’d like to know, ethically, if is she a suitable broodmare. Firstly, is the navicular issue likely to be passed on and secondly, would the additional weight of pregnancy cause her problems? She is on-and-off lame, generally more so when the ground is hard, and her symptoms are easily controlled with small doses of bute.
Sandra B, Hauraki
Vet Dave replies:
Is she ethically suitable for a broodmare? Yes, and then no. Firstly, the yes. She is young enough to be expected to have normal fertility, and should have no problem with the internal medicine side of things with regard to carrying a foal. From an orthopaedic perspective, she should most likely carry a pregnancy with minimal issues, as long as you are happy to treat her with bute during the pregnancy to maintain her comfort levels. There is minimal data on the safety of bute during pregnancy; however, it is a relatively commonly-used drug during pregnancy, and anecdotally there are no major issues with its use. The same would be true for her treatment during lactation, and looking after her foal on the ground.
Then the no. There is definitely a genetic component to navicular disease. It is not a black and white link; as with most things in life it is more a shades-of-grey; however, her needing to retire at eight is less-than ideal and doesn’t bode as well for her progeny.
Secondly, I would get you to question why you are thinking of breeding her. If she has only competed to a low level, and was not a racing prospect, then her future progeny is a longer shot at best to be of good genetic merit, either as a sport horse or a racehorse. I would want her to have an excellent temperament under saddle for her to be producing a future nice horse to ride, and also choose a stallion who has excellent strengths, to counter her weaknesses.
