Distal forearm fractures in dwarf breeds and methods of treatment.

Distal forearm fractures in dwarf dog breeds.

Inbreeding in the name of a breed standard provokes the consolidation of traits that are not the best from the point of view of evolution. The correlation is ironclad - the more popular, smaller and cuter, the more genetic diseases are found in the representatives. In many favorite small breeds (Toy Poodle, Chihuahua, Toy Terrier, Spitz, Yorkshire Terrier, etc.) we regularly encounter pathologies of the musculoskeletal system, namely Perthes disease, patellar instability, rupture of the anterior cruciate ligament, dislocation or subluxation of the shoulder and fractures of the limbs, especially the bones of the forearm.

Statistics. About 84% of all fractures in small dog breeds are distal forearm fractures. Unfortunate jumps from chairs and couches, falls from hands, and similar injuries are the most common cause of fractures in the smallest dog breeds.

Etiology. Why does this happen?The culprit is an anatomical peculiarity - a decrease in the diameter of the intramedullary canal or its complete absence. As an analogy, you can see the appearance of a rod and tube slice (see picture). Such bone structure of dogs of that breed contributes to non-physiological increase of specific stress in the bone, and accordingly its fragility even under relatively small loads.

Clinical symptoms. Dogs with fracture of the paw enter the clinic with pain syndrome, deformity of the limb, pathological mobility and swelling (not always) of the limb, sometimes bare bone is visible, there is no bearing on the diseased limb.

Diagnosis. It is necessary to perform a clinical examination and exclude life-threatening injuries, orthopedic examination and necessarily radiography of the limb in at least two projections. Sometimes a computed tomography (CT) scan may be required.

The most common fracture in this breed of dog is a distal, transverse simple fracture of the lower third of the diaphyseal segment of the ulna/radius (23A3 AO).

Treatment options for fractures A fracture is a serious problem! The earlier surgery is performed, the better the prognosis.

Conservative treatment. Many authors do not recommend the use of conservative treatment in that breed of dog (namely splints, bandages) as monotherapy. The probability of non-union is higher than 80%.

Why plaster immobilization is not recommended:

• Lack of compression;
• Bedsores and other soft tissue injuries with trophic disorders;
• Deterioration of blood circulation as a result of a significant reduction in the functionality of the injured limb;
• Muscle atrophy;
• Muscle and joint contracture;
• Reduced function of the injured paw;
• Secondary displacement of bone fragments;
• Instability of the connected fragments (plaster bandage does not exclude mobility of the fragments);
• Impossibility of accurate and complete juxtaposition of the fragments;
• Inconsistent with the principles of functional treatment of fractures;
• Discomfortable for the animal and the owner;
• Lack of fusion, pseudoarthrosis, lysis (resorption) of the bone.

The standard of care is osteosynthesis (surgical treatment) of forearm fractures in dogs of all breeds.

Types and benefits:

1. Extrafocal fixation

• Provides stable fixation of the fragments = early bearing capacity;
• Atraumatic technique with preservation of blood supply to fragments and bone fragments;
• Early functional loading;
• Treatment of open fractures (good opportunity to care for an infected wound);
• Can be used almost always;
• Faster osteosynthesis than periosteal osteosynthesis;
• Budget-friendly option;
• Biologic type of osteosynthesis with closed technique = early fusion;

2. Periarticular (with LCP plates - locking compression plate).

• Periarticular fractures (small fragment);
• Multifocal fractures (bridge fixation);
• Poor bone quality (young patient, hyperparathyroidism);
• When other techniques are ineffective.

Complications in the treatment of fractures in that dog.
Physiological factors associated with delayed fracture healing: reduced blood flow to the lower third of the radius (anatomical features), lack of soft tissue, lack of intramedullary canal, unwillingness to use the limb and the ability to do without it.

Non-physiological factors associated with delayed / non-union of bone: additional traumatization of tissues during surgical intervention (skeletonization, thermal necrosis of bone during drilling), non-compliance with the basic principles of osteosynthesis, use of inappropriate implants for osteosynthesis (large size).

We do not deny that fracture union can occur with a bandage, but it will be spontaneous, with unpredictable results. The statistics of fracture healing with single spoke fixation is less than 2 out of 10 dogs. The probability of complications with these methods of treatment is high: displacement of the spoke, non-union of the fragments, deformity of the limb, lysis (resorption) of the bone, amputation.
Consequently, osteosynthesis with a plate or bilateral single-plane external fixator is the only comfortable, predictable and reliable method of treatment of forearm fracture in that breed, which gives maximum clinical effect if the basic principles of osteosynthesis are observed.