Common Management-related Diseases in Backyard Poultry
Birds are prey animals, so early signs of illness may be subtle and difficult to discern. Some early signs of illness include changes in eating and drinking habits; dull feathers; soiling of the feathers around nares, vent, shoulders, or eyes; swelling around or discharge around the eyes; discharge from the eyes or nares; abnormal feces; favoring or lameness in limbs; or decrease in activity.
Pecking or cannibalism (see Cannibalism in Poultry) is one of the most frustrating and common problems to control in floor-reared birds. Certain species such as pheasants and quail are notorious for cannibalism, often leading to individual cages as the only housing option. Certain breeds can be more aggressive than others within specific species. Cannibalism usually does not begin in chicks <2–3 wk old, although in young chicks, it is generally the result of insufficient feed or diarrhea (soiled or pasty vents). In mature birds, methods to control cannibalism include reducing lighting, reducing bird density, increasing the number of feeders, and trimming the beaks. If an individual bird has been pecked severely on the skin and separate housing is not available, spraying or painting the affected area with tree pruning tar (pruning sealer) is a quick remedy. After the sealer has been sprayed or painted on the affected area, the bird should be restrained until the sealant is dry. The tar protects the exposed area from fluid loss, is nontoxic on open wounds, and has the advantage of "identifying" the perpetrators by staining their beaks black. If small numbers of birds are the aggressors, these birds can be given red spectacles that attach to their nares, red contact lenses, or have their beaks retrimmed to reduce trauma in other birds.
This is the most common condition of backyard poultry and includes predator injury, entrapment of limbs in cages or other equipment, cannibalism, crushing injuries (stepped on, trapped in doors, etc), and self-mutilation (spurs, beak, nails). Most adult poultry are highly resilient and seem able to recover from severe injuries if the wound has not penetrated into the respiratory or abdominal cavity. Supportive therapy includes providing warmth (via brooder lamp), adequate hydration, and force-feeding warm molasses/sweetened feed. Hydration can be encouraged by offering a half concentration powdered milk instead of water. Superficial wounds can be treated with antibiotic cream and parenteral antibiotics. Most poultry will show evidence of recovery in 2–3 days. If there is no improvement after a few days, the prognosis for full recovery is generally poor.
Although all laying birds retain more fat in their livers than non-layers or males, fatty liver (see Fatty Liver Hemorrhagic Syndrome) is characterized by extreme fat deposition, sudden drop in egg production, and increased mortality. The hens are often obese and have pale combs, and the wattles and combs may be covered with dandruff. The cause is thought to be a combination of fatty feed and decreased exercise. Hens and poultry fed predominantly scratch diet (poultry treats, table scraps) are predisposed. Mortality is due to liver rupture and hemorrhaging, with large blood clots found in the abdomen on necropsy. Treatment is by prevention; most backyard birds have adequate outdoor access for exercise, but the diet must be controlled. Lipotrophic agents and dietary supplements (alfalfa, wheat bran, fish meal, dried brewer’s yeast, soybean mill feed, vitamin E, and torula yeast) have been used with inconsistent results.
Cage-layer fatigue (see Hypocalcemia, Sudden Death, Osteoporosis, or Cage Layer Fatigue (Poultry)) is common in chickens, Coturnix quail, and Khaki Campbell ducks. Birds are unable to stand and have brittle bones. The ribs are often deviated in a sigmoid shape or fractured at the junction of the sternum and vertebra. Paralyzed birds are alert and responsive unless dehydrated. Possible causes include vitamin D3, calcium, and phosphorus deficiencies and/or imbalances. Birds may die acutely (often from fractured spinal vertebrae and severed spinal cords) or can rapidly (4–7 days) recover after placement on the floor with easy access to food and water. With backyard poultry, treatment with vitamin D3 IM or calcium gluconate IV can be helpful. Oyster shells and other large particle calcium sources can be added to the diet ad lib to prevent this condition. The oyster shell must not be ground so small that it passes through the intestinal tract, because it is essential to have slow release of calcium from larger particles being ground in the gizzard. The strain of bird and type of housing also affect incidence. The key is to ensure good nutrition (and good cortical bone formation) just before onset of lay. However, prolonged increase in dietary calcium before production can result in urolithiasis and/or a permanent cessation of parathyroid gland activity.
The vent will prolapse temporarily during normal delivery of an egg. However, slow retraction due to obesity or in poorly developed hens (those that come into lay too early) will attract cannibalism, trauma, and edema formation, which will often prevent retraction. Typically, these chickens are culled, and prevention is practiced by controlling obesity, stocking density of cages, lighting schedules, precocious onset of lay, and proper beak trimming. For backyard poultry, stopping lay (reduced light, sharp reduction in feed), isolating from other birds, and keeping the vent clean until retraction are sometimes effective in mild cases. If chicks are hatched in the fall, increasing light in the spring can induce them to come into lay when they are physically immature. Controlling light is extremely important in this circumstance.
Egg binding is common in pullets brought into production too early or in obese hens. It can range from a temporary egg-binding observed in pullets that lay large eggs to complete obstruction of the oviduct. There can be eggs in the abdominal cavity (retropulsed); single or multiple eggs in the oviduct; or shell membranes, shells, and yolk/albumin concretions in the oviduct. The impaction can generally be identified on abdominal palpation, ultrasound, and/or radiographic examination. Commercial hens are culled. Backyard poultry can sometimes be treated by external reduction (smashing) of the egg within the oviduct and natural elimination, or by surgical removal of the entire oviduct (not ovary). Wrapping the bird in a warm towel and massaging the abdomen toward the vent after use of generous amounts of lubrication around the cloaca can sometimes induce propulsion if the binding is caught early enough. The surgical approach is generally midline; care should be taken to minimize damage to the air sacs. After removal of the oviduct, eggs deposited into the abdominal cavity will be absorbed. Most hens will assume male characteristics (crowing, aggression, spurs) after surgery and are called “pollards” (genetically female, phenotypically male).