Angular Limb Deformities in a Giant-Breed Puppy
A 6-month-old male, 47-kg Tosa-Ken was presented for lameness with bilateral carpal valgus.
History
Beginning 2 months prior to presentation, the dog demonstrated signs of worsening bilateral angulation of the distal extent of the antebrachia; the right forelimb was more severely affected than the left (Figure 1). The patient was being fed a homemade diet of raw whole chicken, vegetables, vitamins, and minerals. With onset of forelimb deformities, the dog was treated with 1500 mg vitamin C Q 12 H; there was no improvement.
Physical Examination
Carpal valgus was present bilaterally but worse on the right side. The dog was moderately overweight with a body condition score (BCS) of 7/9. Pain was present on flexion of the right carpus and right forelimb manus; the right carpus and digits knuckled over when the patient walked.
Imaging
Radiographs of both antebrachia were obtained. Bilateral mild carpal valgus centered at the antebrachial carpal joint with foreshortening of the ulnas was present (Figure 2). The right third and fourth metacarpals had distal valgus deformities involving the distal physes (Figure 3).
ASK YOURSELF...
Given the age and breed of the dog presented here, what are the most appropriate diet changes you would recommend to the client?
A. Continue with the current diet of raw chicken, vegetables, vitamins, and minerals.B. Recommend the addition of vitamins C and D to the home diet.C. Recommend an adult maintenance commercial diet for large/giant breed dogs that is fed in accordance with the dog's calculated energy requirements.D. Recommend a puppy-stage commercial diet for large/giant breed dogs that is fed in accordance with the dog's calculated energy requirements.
CORRECT ANSWER:
C. Recommend an adult maintenance commercial diet for large/giant breed dogs that is fed in accordance with the dog's calculated energy requirements.
Developmental orthopedic disease has multifactorial causes, including excess calcium and phosphorus intake, genetics, overnutrition, trauma, and ischemia.1 The homemade diet was most likely not balanced for this giant-breed puppy's energy, calcium, phosphorus, and vitamin D requirements.
In one study, overnutrition and excess energy consumption in Great Dane puppies increased the incidence of developmental orthopedic disease.2 Calorie restriction has been implemented in commercial large-breed puppy foods by limiting the energy density to 3.5 to 4 kcal/g and 12% fat content, which limits growth rate and fat deposition.
Bone Disorders & Diet
High-fat diets may result in increased levels of insulin-like growth factor-1 and increased bone formation, leading to bone deformities such as those seen in the case presented here.3
In addition, developmental bone diseases, such as angular limb deformities, have been linked to excess dietary calcium intake as well as calcium-phosphorus ratios greater than 1.2 to 1.1,4,5 Many home-cooked and raw-food diets have high phosphorus contents but restricted calcium content, which causes nutritional secondary hyperparathyroidism.1 The result is asynchronous growth of the long bones due to imbalance of mineral accretion and resorption.1
Vitamin supplementation can also result in developmental bone disease in large-breed puppies. Excess vitamin D supplementation can alter skeletal development, but more research is needed to determine the mechanism of this process. Commercial diets contain ample levels of vitamin D and no additional supplementation is recommended at this time.1
Treatment
Since this puppy was overweight, the recommended diet was a large-breed maintenance adult dog food fed according to the following formula:
RER = 30(body weightkg) + 70
1.6 ¥ RER = maintenance energy requirement (kcal/day)
If the puppy had not been overweight (eg, BCS less than 4.5/9), the recommended diet would have been a large-breed puppy food fed at 2 ¥ RER until 1 year of age.1
In addition to the diet changes, bilateral distal ulnar ostectomies and T-plate fixation of distal third and fourth right metacarpal angular deformities were performed (Figure 4).6
Follow-Up & Outcome
Determination of BCS and body weight were performed every 2 weeks. The energy intake and amount of food consumed by the puppy were altered as needed. Within 4 months there were no signs of angular deformities in either forelimb and all lameness had resolved.
Carpal Laxity Syndrome
This dog may have had a component of carpal laxity syndrome, which results in hyperextension or hyperflexion of the carpal joints in puppies. Carpal laxity syndrome may be the result of unbalanced growth or poor muscle tone between the carpal flexors or extensors.7,8 It most commonly occurs in large- and giant-breed dogs; immature dogs often develop this condition as a result of excessive weight gain before adequate bone development.7,8
Treatment for carpal laxity syndrome is multimodal and includes feeding a balanced diet, applying splints and/or Robert Jones bandages, and limiting exercise to surfaces with good traction. The prognosis for most dogs is good, and the condition is often self-limiting with resolution of clinical signs within 1 to 4 weeks of treatment.7,9
Take-Home Messages
• Dietary requirements of large-breed puppies are markedly different from those of other breeds. A strict feeding regimen prevents or at least decreases the incidence of developmental orthopedic diseases.• Calorie as well as dietary fat, calcium, and phosphorus requirements must be carefully regulated. BCS should be monitored closely in order to decrease the incidence of orthopedic disease.