Prevalentdiseases of ostrich chicks farmed Canada · 2017-07-02 · ostrich farming is highest in chickunits. Anincreased chicksurvival rate impactspositively onpro-ductionandprofit.

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Prevalent diseases of ostrich chicks farmedin CanadaJudith Samson

Abstract- In Canada, ostriches are now slaughtered for their meat and hides. The mortality rate inostrich farming is highest in chick units. An increased chick survival rate impacts positively on pro-duction and profit. This paper will focus on common health disorders that affect chick productioncosts. These are discussed under the following categories: digestive, orthopedic, respiratory, and integu-mentary disorders. Methods for elimination or reduction of these mortality factors are also discussed.

Resume - Prevalence des maladies chez les autruchons eleves au Canada. Les autruches sontmaintenant abattues pour leur viande et leur cuir. Le plus haut taux de mortalite dans les elevagesse situe chez les autruchons. Une augmentation du taux de survie des autruchons a un effet positifsur la production et le profit. Les principaux problemes de sante qui influent sur le cou't de productiondes autruchons sont discutes selon la classification suivante: problemes digestifs, orthopediques,respiratoires et maladies des teguments. Des methodes pour eliminer ou reduire ces facteurs de mortalitesont aussi discutees.

(Traduit par docteur Andre Blouin)Can Vet J 1997; 38: 425-428

Ostrich farming is an alternate agricultural enterprise,which started in western Canada in the early 1990s.

Today, ostriches are being slaughtered at approximately1 y of age for their meat and hide. This relatively newindustry will be viable as long as farmers produce goodquality birds for market in the most economical andhumane way. At present, however, 1 of the weakestareas in ostrich farming is the relatively high chickmortality rate experienced when the birds are less than3 mo of age. Although early mortality is a characteris-tic of most livestock, it is particularly prevalent inostrich chicks, due to prolonged confinement over the falland winter. Additionally, high morbidity results in areduced growth rate during that time.

This paper focuses on the most common conditionsaffecting ostrich chicks raised in Canada. These problemsare divided into digestive disorders, orthopedic problems,respiratory disorders, and integumentary anomalies.Immediate post-hatching problems are not discussed.

Digestive disordersImpactionThis condition is characterized by an excessive accu-mulation of ingested material in the proventriculus and

Ratite Health Management Services, Box 13, Site 1, R.R. #1,Calgary, Alberta T2P 2G4.This paper has been peer-reviewed.

Figure 1. Distended and impacted proventriculus contain-ing fiber and pebbles.

ventriculus that is not being propulsed normally into thesmall intestines (Figure 1). Impactions may be classifiedas acute (blockage that leads to debilitation within a fewdays) or chronic (blockage that leads to debilitationwithin weeks to months), hard (rocks, sand) or soft(fibrous material, such as, alfalfa hay and grass), andpartial or complete.

Eighty-five percent of impactions are observed inbirds 6 mo old or less (1). Impactions can lead to gastricstasis, whereby the contractions of the ventriculus stop,and koilin hypertrophy develops along the ventricularsurface (2).

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The most common clinical signs include failure tothrive, abnormal passage and quantity of feces, and a dis-tended proventriculus, which can be palpated on theleft side of the abdomen, cranial to the leg. Diagnosis canbe made by palpation, especially in the case of a hardimpaction, and by radiography or ultrasonography.Mild impactions can be relieved by flushing the proven-triculus with water, mineral oil, or diluted propylene gly-col (1:10). Severe impactions can only be relieved witha proventriculotomy (3) or an esophagostomy to removethe impacted material. The prognosis following surgeryis very good, if the impaction is detected early and hasnot yet caused excessive distension of the proventricu-lus. If the latter has existed over an extended period oftime, gastric atony will likely ensue after surgery, lead-ing to starvation and death.Common materials to be found in impacted proven-

triculi include long-stemmed alfalfa hay, grass, straw,rocks, and wood stems. Impactions appear to be stress-related (4), and thus are more common when chicksare exposed to such stressors as confinement; high pendensities; loud irregular noises, such as from nearby con-struction; and excessive human handling. Ostriches feda fibrous nonpelleted diet must always have access tosome form of grit to assist in the prevention of impaction.A chick relieved of an impaction will impact again if thestressors or the offending materials are not removedfrom the environment. As ostrich chicks thrive on socialfacilitation and mimic one another's behavior, all birdsin a pen must be checked when an impaction has beendiagnosed. If 1 chick has ingested too much material,other chicks are likely to have imitated the same abnor-mal ingestive behavior.

Hardware diseaseThis disease, well documented in cattle and ostriches,involves the ingestion of sharp metal objects with anensuing perforation of the gastrointestinal tract. Thecondition can be difficult to diagnose. Clinical signsinclude inappetence, loss of body condition, and scantpassage of feces (5). Undetected hardware disease inostriches can lead to gastric stasis. I have seen birds pre-senting no pain on abdominal palpation and havingnormal hemograms, even in the face of peritonitis.Metal detectors and radiographs can be used to detect thepresence of some items, but are not reliable in ascer-taining that these are causing abdominal problems.Surgical removal is the only therapeutic choice forhardware disease.

Cloacal prolapseThis condition is usually seen in birds less than 3 mo oldand is generally associated with intestinal problems (5).I have observed the condition most often in chicks notdrinking enough water, resulting in the passage of dryfeces with dyschezia, followed by a prolapse of thecloacal tissue (Figure 2). Cryptosporidial enteritis alsohas been implicated in cloacal prolapse in young ostrichesin South Africa, as well as in adults imported intoCanada from Botswana (2). Depending on the causeand severity of the condition, therapy will involveapplication of an anti-inflammatory antibiotic oint-ment, replacement of the swollen tissue into the cloaca

Figure 2. Cloacal and rectal prolapse in a 4-week-old chick.

under anesthesia, and placement of a purse-string suturethat will allow defecation. Adequate hydration can bemaintained with regular gavage if affected birds arenot drinking enough, and oral or parenteral antibiotictherapy may be warranted.

Bacterial enteritisThis condition is most commonly observed in ostrichchicks less than 6 wk old. Affected chicks exhibitdepression, diarrhea, and dehydration. Bacterial enteri-tis is most prevalent when management practices areinadequate, that is, when hygiene is poor, overcrowdingexists, and stressful factors, such as, improper temper-ature and excessive handling, are present (5). Necroticenteritis is a common form of bacterial (Clostridium spp.)enteritis diagnosed in Alberta. The pathology involvesnecrosis of the intestinal wall, characterized by a cheese-like lining and contents (2,5). Gas in the intestineswithout lesions is not indicative of enteritis.

Since coprophagia is a normal behavior in ostrichchicks, bacterial enteritis rapidly becomes contagious.Treatment and control of this condition includes cor-rection of the inadequate management practice, optimalsanitation to prevent spreading of the disease betweenpens, and the use of proper antibiotics based on cultureof the intestines. The use of probiotics immediatelyafter hatch, based on the principle of competitive exclu-sion, seems beneficial in curtailing the problem (2,5) andI have used them successfully.

Orthopedic disordersRolled toesThis condition is most often observed in chicks lessthan 6 wk old, where 1 or both main toes roll laterally.The etiology is unknown but may include genetic

aberrations, incubation problems, or an inadequate sub-strate that causes slipping (1). Huchzermeyer (2) hasreported riboflavin deficiency as a cause for rolled toesyndrome. Rolled toes can easily be corrected by applyingcorrective shoes (6). I recommend regular nail trimming,since once a toe has rolled, the nail will overgrow and pre-vent the affected toe from returning to its normal position.

Rotational deformities of the legThis syndrome most often involves a thickening and a lat-eral deviation of the tibiotarsometatarsal joint in chicks

426Can Vet J Volume 38, July 1997426 Can Vet J Volume 38, July 1997

Figure 3. Deformed rib cage of a 9-week-old chick that alsosuffered from a chronic angular leg deformity.

Figure 4. A 3-week-old chick with an acute lateralrotation of the left leg.

less than 3 mo old (Figure 3). The deviation can cause

1 foot to rotate as much as 180° from the dorsoplantaraxis of the normal leg in only a few days. In general, only1 leg is severely affected. Several etiologies have beensuggested: low serum calcium (7), rapid weight gain froma high protein starter ration (8,9), and genetic aberra-tions (1). Deformation of the chest wall with a skewingto 1 side has been noticed coincident with leg rota-tions (5) (Figure 4). I have observed hatchlings withskewed chest walls that have subsequently developed a

leg rotation, likely as a result of an abnormal stancecaused by the chest deformation.A prevalence of chicks with leg deformities greater

than 5% of the chick population on a farm usually indi-

cates a mismanagement problem that requires correc-

tion (10). Observations from Canadian ostrich farmsexperiencing severe leg rotation problems shared somecommon characteristics: chicks growing too fast with-out proper exercise (body weight exceeding 4.5 kg at28 d of age); hard substrate, such as cement floors,with high indoor pen densities, leading to frequent fallsand presumably traumatic injuries to growth plates of thetibiotarsometatarsal joints; malnutrition due to defi-cient diets; and impaction problems.

Surgical corrections of leg deformities have beenattempted but with poor results (1). These include dero-tational osteotomy and periosteal stripping. Conservativetherapy, such as the use of anti-inflammatory drugsand increased exercise, may work if the leg is only min-imally rotated outward (less than 150). Consideringpresent market prices, breeders generally euthanize anybirds exhibiting leg deformations and forego expen-sive treatments.

Slipped tendonsThis term is used to describe a lateral slip of the gas-trocnemius tendon over the tibiotarsometatarsal joint.The condition is most often observed in birds that are lessthan 6 mo old, but it can occur in older birds. The prog-nosis is fair for young birds, provided that the skinover the tibial condyles has not ruptured. If a rupture hasoccurred, euthanasia is usually recommended. Treatmentinvolves replacing the tendon in the tibial groove andholding it there with bandages on either side of thejoint but not across the cranial aspect to prevent skin lac-eration. Birds older than 6 mo suffering from a slippedtendon are euthanized immediately, as the prognosisfor recovery, whether the skin is ruptured or not, isextremely poor.The Achilles tendon can also slip medially over the

tarsometatarsophalangeal joint in young chicks. Thereis usually no successful treatment, unless detectionis early, in which case bandaging the tendon back inits normal position may resolve the problem. Mostaffected chicks will develop an abnormal stance withensuing leg deformities or poor growth, presumablydue to pain.

Respiratory disordersRespiratory problems are common in ostriches of allages, especially when they are confined for long periodswith inappropriate ventilation (1 1). Lower respiratoryproblems, such as, unilateral or bilateral air sacculitis andpneumonia, present with similar clinical signs, suchas, open-mouth breathing at rest, chest excursion withinspiration, and exercise intolerance.A specific antemortem diagnosis can be reached by

culture for bacterial growth and a smear of the sputumto check for fungal hyphae. Sputum can be obtainedby massaging and putting pressure on the trachea toelicit a cough. Other diagnostic techniques, such as

transtracheal and air sac washes, are also valid but usu-

ally cost-prohibitive for farmers.I have recovered the following bacteria from the

trachea and air sacs of affected birds: Klebsiella spp,

Escherichia coli, Pseudomonas spp, Corynebacteriumspp, and alpha Streptococci, and fungi (Aspergillus

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Can Vet J Volume 38, July 1997 427

spp). Chronic respiratory diseases in chicks less than6 mo old usually have a poor prognosis, regardless of theinfectious agent involved, since affected birds soonbecome anorexic or, at best, inappetent. Gavage may beattempted if affected birds are not cyanotic. If they arecyanotic, the stress from handling and tube-feedingoften terminates these birds.High ammonia levels from urine excretion and high

dust levels in indoor pens will exacerbate respiratoryproblems. This explains why the prognosis for recoveryis often worse in winter, when birds are confined, thanin summer, when birds are continuously outside.

Integumentary disordersFeather peckingIn ostriches, feather pecking is a social behavior; that is,birds will peck the feathers of penmates rather thantheir own. This abnormal behavior seems precipitated byovercrowding, boredom, or sleep disturbances, such asexcessive lighting at night (12). In juveniles and adults,feather pecking is strongly seasonal, with severe occur-rences in the winter when confinement is prolonged (13).

In young chicks, this aberrant behavior seems con-tagious. Since social facilitation is a strong behavioraltrait in ostrich chicks, feather pecking soon becomes con-tagious within a pen. Therefore, as soon as a chick isobserved feather pecking penmates, it should be movedto a pen with older and larger birds.

Pantothenic acid deficiencyClinical signs of pantothenic acid deficiency include lossof appetite and reduced growth, dermatitis with inflam-matory changes in the corners of the beak and eyelids,and roughening and loss of feathers (14). Althoughthese abnormalities have been experimentally induced,they rarely occur in poultry (14), whereas they are notuncommon in ostriches (1,15). I have observed signs inmalnourished ostrich chicks, that is, chicks that werechronically impacted or had ingested excessive amountsof grass and dirt. They can be resolved by correction of themalnutrition problem, in addition to daily injectionsof vitamin B complex.

Currently, farms with excellent husbandry techniquesshould aim for a chick mortality no greater than 20% (10).This, however, includes post-hatching losses, such as,inappropriate weight loss during incubation, congenitalanomalies, omphalitis, and yolk sac retention, whichwere not discussed in this paper. Most producers ven-turing into ostrich farming have difficulty in under-standing the deleterious effects of stress and confine-ment, and hence the prevalence of the above disorders.Large exercise pens are mandatory to raise healthyostrich chicks. When ostrich chicks are allowed to exer-cise properly, they are less likely to behave abnor-mally. Coprophagia, dietary indiscretion that leads toimpaction, hardware disease, and bacterial enteritiswill be reduced. Additionally, the prevalence of legproblems, such as, rolled toes and rotational deformities,are less likely to occur, and respiratory disorders aremuch reduced in the summer when birds are exercisedoutside. Ostrich rearing in a cold climate can be suc-cessful but requires excellent husbandry techniquesand sound infrastructures. cv.

ReferencesI. Stewart JS. Ratites. In: Ritchie BW, Harrison GJ, Harrison LR, eds.

Avian Medicine: Principles and Application. Fort Worth, Florida:Wingers Publishing Inc, 1994: 1284-1326.

2. Huchzermeyer FW. Ostrich Diseases. Agricultural ResearchCouncil, Onderstepoort, Republic of South Africa, 1994.

3. Gamble KC, Honnas CM. Surgical correction of impaction of theproventriculus in ostriches. Compend Contin Educ Pract Vet 1993;15: 235-244.

4. Hicks K. Ostrich pediatric disorders. Ostrich Rep 1992; August:13-18.

5. Foggin CM. Veterinary problems in ostriches. In: Hallam MG, ed.The Topaz Introduction to Practical Ostrich Farming. Harare:Ostrich Producers Assoc Zimbabwe 1992: 61-95.

6. Wade J. Ratite pediatric medicine and surgery neonatal prob-lems. Proc Annu Conf Assoc Avian Vet 1992: 343-353.

7. Chang PH, Chang CF, Liul MRS, Wang KP. Bow leg syndrome inostrich (Struthio camelus). J Chin Soc Vet Sci 1988; 14: 17-21.

8. Guittin P. Croissance de l'autruche en parc zoologique. Can J Zool1987; 65: 3056-3061.

9. Jensen JM, Johnson JH, Weiner ST. Husbandry and MedicalManagement of Ostriches, Emus and Rheas. College Station,Texas: Wildlife and Exotics Animal Teleconsultants, 1992:124-127.

10. Samson J. Targets of performance in ostriches. Proc Annu ConfAssoc Avian Vet 1996: 14 1-147.

11. Samson J. Ostrich diseases and management in northern climate.Proc Annu Conf Assoc Avian Vet 1996: 149-15 1.

12. Stewart JS. Ostrich behavior and behavioral problems. Proc AnnuConf Assoc Avian Vet 1994: 103-109.

13. Samson J. Behavioral problems of farmed ostriches in Canada.Can Vet J 1996; 37: 412-414.

14. Jordan FTW. Poultry Diseases, 3rd ed. London: Bailliere Tindall,1990: 305-306.

15. Foggin CM. Pathology of common diseases of ostriches. Proc S AfrVet Assoc Bien Natl Cong 1992: 149-153.

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428 Can Vet J Volume 38, July 1997