Born in 1835 he qualified MRCVS (Edinburgh) in 1855 and as Veterinary Officer to the 17th Lancers regiment came to Natal in 1879. He was wounded at the battle of Ulundi that same year. He also completed a second tour of duty in Natal with the Army Veterinary Department in Natal from March 1881 to 1882. For a period of 10 months during his first period of duty he served as Principal Veterinary Surgeon (P.V.S.) to the A.V.D. in succession to S. Longhurst. During 1880 the A.V.D./A.V.C. had no representatives in South Africa, but by the time his second tour of duty commenced in Natal in 1881 he had 7 veterinarians serving under him viz. F. Duck, J. Reilly, G. Durrant, W.D. Sartin, W. Pallin, C. Rutherford and T. Caldecott.
On 22 July 1881 (GN 315 of 1881) he published a paper on Glanders and Farcy for general information. On 1 November 1881 (GN 448 of 1881) he published a further paper on "Horsesickness or Anthrax" in South Africa. In this article he stated that "Horsesickness is Anthrax". Like Duncan Hutcheon, S. Wiltshire and other he considered the two conditions to be one single disease. He returned to England in 1882 and was succeeded by F. Duck and P.V.S. of the A.V.D. in South Africa. On 28 June 1890, he was appointed P.V.S. of the A.V.C. in England in succession to Flemming, although he should have retired the day before Flemming. However, some scandal caused Flemming's retirement instead.
J.D. Lambert continued to served as Director-General, A.V.C. until June 1897 when he retired and was succeeded by F. Duck who had also succeeded him as P.V.S. (Natal) in 1882. (The title of the post was changed in 1981 from P.V.S. to Director-General). He died on 3 March 1905. Lambert took part not only in the Zulu War of 1879, but also in the Transvaal Campaign of 1881/82. He was appointed Companion of the Bath in 1891.