Rockets is a relatively rare metabolic disease of cattle seen worldwide.
In cattle, the most common causes are a dietary insufficiency of phosphorus or vitamin D.
This disease is often associated with grazing low phosphorus pastures such as swedes (Brassica napus), although cattle feeding on calcium deficit or phosphate excess diets are not involved in the development of this disease.
An inadequate Ca:P ratios in feed plays an important role in pathogenesis. Subsidiary causes such as restricted movement of the animals and mechanical trauma may exacerbate the condition in cattle.
Clinically affected cattle are usually young and symptoms often appear 2 - 3 months after weaning. Spontaneous fractures, joint pain, sudden onset lameness and reluctance to walk are characteristic.
Diagnosis is based on presenting clinical signs and blood results showing hypophosphatemia and/or hypocalcemia. Radiographic examination usually reveals increased width and distortion of the metaphyses and decreased radiopacity of the epiphyses. In advanced cases, calves present with angular limb deformity.
A differential diagnosis would include congenital diseases which affected joint development such as osteopetrosis, achondrogenesis, arthrogryposis multiplex, complex vertebral malformation, congenital chondrodystrophy, contracted flexor tendons and contractural arachnodactyly (Fawn calf syndrome).
Treatment is usually aimed at correcting dietary deficiencies, supplementation with vitamin D, usually parenterally and palliative care of calves by providing soft bedding and restricting movement until bone remodelling occurs.
- Thompson KG & Cook TG (1987) Rickets in yearling steers wintered on a swede (Brassica napus) crop. N Z Vet J 35(1-2):11-13
- Seffner W et al (1979) Histometric studies of functional assessment of the parathyroid glands in healthy and sick cattle. Arch Exp Veterinarmed 33(6):809-818
- Lalov Kh et al (1976) Study of disorders in calcium and phosphorus metabolism in the intensive fattening of young cattle. Vet Med Nauki 13(1):8-22
- Merck Vet Manual