Like humans, animals also have metabolic disorders. Unlike humans, there are a wide array of metabolic conditions that can occur in various species. Reptiles, birds, horses, dogs and cats are just a few of the species that have species specific metabolic disorders. Metabolic storage disorders usually result from the body’s inability to break down some substance because of partial or complete lack of a certain enzyme. The substance can build up to a toxic level, or the body is unable to produce a substance that it needs. Although storage diseases are often widespread throughout the body, most clinical signs are due to the effects on the central nervous system. Metabolic storage disorders can be either genetic or acquired. Let’s give a few examples.
Metabolic Bone Disease (MBD). The bearded dragon is a well-known lizard currently considered one of the best pet lizards. There are eight species of bearded dragons, but the most popular one is the inland or central bearded dragon (Pogona vitticeps), from the arid to semi-arid southeastern parts of Australia. The information in this handout refers to the inland bearded dragon. Metabolic bone disease (MBD), or nutritional secondary hyperparathyroidism, is a complex disease and is probably the most common health problem of pet bearded dragons. It is most often seen in juvenile bearded dragons (less than 2 years old). MBD is generally caused by feeding an improper diet that is high in phosphorus and low in calcium or Vitamin D3 (caused either by a direct nutritional deficiency of vitamin D3 or a lack of exposure to UV-B light required for lizards to make vitamin D in their skin).
Common signs include swelling of the lower jaw, softening of the jaw and facial bones (‘rubber jaw’), and/or swelling of the hind limbs (fibrous osteodystrophy). Blood tests may show a low calcium level and an imbalance of calcium and phosphorus, with phosphorus being higher than calcium, instead of in the 2:1 calcium to phosphorus ratio desirable in reptiles. As the condition progresses, muscle twitching, seizures, loss of appetite, and loss of energy (lethargy) are seen. Having a discussion with the veterinarian over proper lighting and diet are essential in trying to prevent MBD in bearded dragons.
Birds—Psittacine and Passerine Birds
Metabolic Bone Disease (MBD). The metabolic bone disease complex is once again the winner in any contest of nutritional disease in birds. In juvenile, growing birds, MBD is manifested as rickets (similar to humans), and characterized by stunted growth, bowing of the legs, swollen joints, spontaneous fractures, inability to perch and poor plumage development
Mature birds develop osteomalacia, or demineralization of bone (softening of the bones). The clinical signs are usually more subtle and develop at a slower rate in adults as compared with immature birds. Nonetheless, the effects are severe. Some birds may not take flight as a result of this. Egg production may fail or soft shelled eggs are laid. Once again, diet and nutrition play a key role in treating and even preventing MBD.
Equine Metabolic Syndrome (EMS) is characterized by three main features: obesity or regional adiposity (accumulation of fat in certain areas, particularly the neck), insulin resistance (IR) a “pre-diabetic” like state, and laminitis in horses and ponies (which can be very serious in horses)
Laminitis (or “founder”) is a devastating feature of EMS. Laminitis is a painful and debilitating disease of the digital laminae (the tissue inter-connection between the coffin bone and hoof wall). Often by the time clinical signs are recognized, crippling body changes such as sinking and rotation of the coffin bone have occurred. Although there are several inciting causes of laminitis, the most common form of the disease is “grass founder” which occurs in horses and ponies kept on pasture.
Treatment for equine metabolic syndrome involves dietary management and, if diet and exercise is not enough to treat the disease, then medical therapy is warranted. Correction of the diet may be all that is needed to return the horse to normal body weight. Dietary carbohydrate restriction is very important to help decrease glycemic and insulinemic response. In addition, total calorie intake is restricted to help reduce body weight.
Hyperthyroidism. The hormones produced by the thyroid regulate many other body systems and play a key role in how quickly our pets’ bodies use energy. Cats with hyperthyroidism have an overactive thyroid, making for a lightning fast metabolism. Affected cats generally lose weight despite a voracious appetite. Before you call these cats lucky, remember that hyperthyroidism also has a negative impact on other body systems, such as the heart. A blood test, physical exam and some other diagnostics are needed to make the diagnosis. Treatment involves either radioactive Iodine-131, oral medication or prescription diet. Interesting fact, in general, cats are more prone to hyperthyroidism and dogs are more prone to HYPOthyroidism!
Vitamin A Responsive Dermatosis. Although this disorder can become irritating to dogs, it is not painful. While the cause is unknown, genetics are suspected, and while it is not related to a dietary deficiency, it is known to be a lack of the vitamin in the skin itself. The condition responds well to treatment with large doses of Vitamin A. This diagnosis may be a diagnosis by exclusion, meaning a full dermatologic database by the veterinarian is needed in order to rule this diagnosis in.
Vitamin A-Responsive Dermatosis is a rare condition that usually affects the skin predominately on a dog’s chest and abdomen, resulting in dermatitis-like scaly crusty skin.
While treatment with high doses of vitamin A does work to correct the disorder, providing the skin a chance to recover, careful dosage needs to be administered. An over supplementation can result in a toxic result causing further difficulty and harm to dogs.
Combining the Vitamin A supplements with a medicated shampoo that contains benzoyl peroxide will clear the follicular area and remove crusting. Using this shampoo two to three times per week will remove the debris from around the follicle and hasten healing.