Abstract

Backyard hens are continuing to grow in popularity for their appeal as a local source of fresh eggs. However, they often become a beloved pet and part of the family. When these hens present for being sick, families want veterinary care but are often not prepared to spend as much as for other companion species. This masterclass will review the most common presentations for sick pet hens and present some quick diagnostics to help guide owners’ decisions in treatment options.

Introduction

Backyard chickens are increasingly being allowed in cities, and clients are keeping them for fun and eggs. Urban clients will often develop strong emotional bonds and consider them pets on the same level as their companion cats and dogs. However, preventative care is not common, so these pets will usually present very sick without any prior medical history. Chickens are adept at hiding signs of disease, and novice keepers will likely miss subtle clinical signs of disease¹; because of this, sick chickens should be considered an emergency. Please note: Many “traditional” infectious diseases are not going to be covered in this class, as there is a plethora of literature, treatments, and quarantine recommendations from the production poultry literature. This talk will be focusing on the hen with generalized symptoms, which often presents on emergency.

Veterinary Examination and Diagnostics

History

Collect all history from the owner—may be a clue to the current condition or can spur a husbandry conversation for after the crisis. Be sure to ask the following:

• Signalment: Age, breed, standard or bantam
• Acquisition:
• When was the bird obtained?
• From private party or hatchery? Did the previous owner get from a hatchery?
• If from a hatchery, were any vaccinations given?
• How long (and where) did the owner quarantine after obtaining?
• Husbandry (ideally house visit, or ask for pictures):
• Winter housing (temperature, humidity, substrate, roosts, nest boxes, frequency of cleaning, airflow, etc.)
• Summer housing (temperature, humidity, substrate, roosts, nest boxes, frequency of cleaning, airflow, etc.)
• Free range, fenced, netting top, other?
• How many birds in flock, age, sex, size, breed, and personalities; where is this bird in the pecking order?
• Last time a new bird was added to flock
• Food and water
• Clean water available and changed daily? How many places? Out of sun/cold?
• Fresh feed offered daily? How many places?
• What kind of feed?
• Calcium supplement offered?
• Any other foods offered?
• How often/how much treats? Table scraps, etc.?
• Laying history:
• For how many years?
• Frequency of egg laying?
• Last time hen laid?
• Size of egg?
• Any abnormalities on the eggs (blood on shell, calcium deposits, abnormal shape or size, shell-less eggs)?
• Recent broodiness?
• Prior medical issues?
• When did owner first start to notice something off with hen? What was noticed?
• Appetite?
• Feces/urates?
• Activity level?

Physical Exam

Perform as in any other species and pay attention for any of the following abnormalities:

• Hands-off exam: Watch for any dyspnea (tail bobbing, any obvious/exaggerated inhalation/exhalation, OMB, etc.)
• Beak, mouth: Look for any plaques, stringy saliva, color of mucous membranes, beak discoloration
• Eyes: Clear, open and bright? Or half-closed, sunken, dull? Ensure no swellings around eyes
• Comb/wattle: Color and size—ask owner if it is redder/larger or paler/smaller vs. when the hen is laying normally
• Feathers/skin: Look for lice, mites, any areas of feather loss or wounds? All feathers preened and out of sheaths? In good condition and fresh or worn and damaged? Stress bars?
• Crop: Is it full? Distended? Palpate, and what do you feel—feed? Hay? Mats? Liquid? Gas?
• Auscultation: Listen to heart for murmurs. Listen to each air sac individually, as each can insulate sounds from the others
• Vent: Clean? Feathers around vent full of feces? Diarrhea?
• Caudal/ventral coelom: Palpate—is it enlarged/distended? With fluid or soft tissue? Painful?
• Ascites and/or coelomic distention is an incredibly common abnormal physical exam finding in the ADR hen

Two-View Radiographs

Ventrodorsal and lateral views are required with any ADR hen. They can quickly be done in a low-stress manner without anesthesia. Sedation (0.5 mg/kg midazolam IM ± 2 mg/kg butorphanol IM) is great to use in any hen, but especially necessary in stressed individuals or those in respiratory distress.

Evaluate the entire radiograph and be sure to evaluate the opacities of the caudal coelom and relative location of the ventriculus to the rest of the coelomic contents.

Ultrasound

Great for internal examination and for therapeutic coelomic centesis

Blood Lead Levels

Lead is in surprising places in the environment, and many chickens may have detectable blood lead levels. Any blood lead level above 10 µg/dl should be chelated, and the eggs should be discarded, as lead can pass into the egg and onto humans if eaten.²

Common Diagnoses

Secondary Comorbidities

Owners may come in with the following as a primary problem, but they are almost always a secondary comorbidity. Search and find the primary pathology!

• Gastrointestinal parasites
• Lice, mites
• Crop stasis
• Diarrhea of unknown origin

Primary Pathology

• Neoplasia: Is common in any area, but often will arise in the reproductive tract
• Hard to diagnose; it is a diagnosis of exclusion usually
• Exploratory celiotomy can sometimes reveal carcinomatosis
• Reproductive problems:
• Ectopic eggs (yolks only or partially/completely shell) are when developing egg(s) enter the coelomic cavity through an oviductal rupture or reverse peristalsis from oviductal (masses, impactions, salpingitis), cloacal, or unknown reasons.³ Ectopic eggs are often termed “internal laying” and may result in a sterile or non-sterile coelomitis.
• Impacted oviduct: Salpingitis (sterile,³ caused by E. coli or E. coli found secondarily⁴), cystic hyperplasia, metritis, neoplasia, or unknown etiologies may cause caseated material to form—often in layers around misshapen/ruptured/soft-shelled/partially formed egg pieces.³ This material can cause oviduct impactions if it gets big enough. This material can be laid whole or in pieces if small enough and are often termed “lash eggs.” Lash eggs are most common in older, prolific-laying breeds.
• (Less common) gout/urolithiasis⁵
• Often due to laying feed fed to hens (or rooster) not in lay
• Predisposing factors: Infectious bronchitis, prior renal damage, water deprivation
• (Less common) elevated blood lead levels: Chickens are stoic and often do not have overt clinical signs related to mildly elevated lead levels, but they likely have subclinical/underlying problems caused by the lead. Lead will also make recovery from any other condition more difficult, so it should be chelated whenever >10 µg/dl.

Uncommon Diagnoses

• Egg-binding, dystocia: Uncommon in poultry (occur in small bantams)³
• Primary crop impaction: Crop stasis or GIT stasis is almost always due to an underlying disease process, unless the hen is a meat breed

Treatments

Legalities

In the United States (and in many other countries⁶), all chickens are considered meat animals even if owned by a vegan on a farm sanctuary. It does not matter if the bird or eggs will never be used as food; in the U.S., simply being this species makes it a food animal in the eyes of the FDA.⁷

Below is the list of drugs that are prohibited from extralabel use; these drugs may never be used in chickens:

• Antivirals
• Cephalosporins
• Chloramphenicol
• Clenbuterol
• Diethylstilbestrol
• All fluoroquinolones, including enrofloxacin (any -oxacin)
• All glycopeptides, including vancomycin
• All nitroimidazoles, including metronidazole
• All nitrofurans, including nitrofurazone
• Indexed drugs
• Example: Suprelorin F (Virbac)

FARAD has addressed egg residues.⁷

Supportive Care

Necessary with any diagnosis and will make an incredibly huge difference in the attitude of the hen.

• Subcutaneous fluids: 50 mg/kg/day (great to add in vitamin B complex 1–3 ml/L, and if patient has been inappetent for a few days, 30 mEq/L KCl). Monitor hydration BID and supplement SC fluids as needed.
• Analgesia: Recommended in all conditions. The author prefers meloxicam (1 mg/kg BID), recognizing this can make a gout case worse.
• Nutrition: Oftentimes these hens will be anorexic for some time. Switching to a higher-quality feed or moistening the food may entice hens to eat. Feel free to use insects (mealworms, earthworms, etc.) to entice, as well as fresh fruits and vegetables. Monitor weight daily, and if patient is losing weight or is anorexic, gavage feeding is necessary. If prolonged anorexia, start with recovery formulas for birds. If only off feed for a few days, moisten high-quality feed, blend, and gavage 30 ml/kg/feeding. Feeding BID is usually adequate.

Treatments of Specific Conditions

• Neoplasia:
• Supportive care
• Coelomocentesis if ascites; ultrasound can help guide
• If legal in one’s country, deslorelin may help slow the progression of some neoplasias,^8,9 but it is not legal to use in the U.S. for species other than ferrets for adrenal disease.
• Reproductive problems:
• Supportive care
• If legal in one’s country, deslorelin is implanted as soon as possible. This will put the hen out of lay,¹⁰ stopping the problem from compounding and buying some time.
• Two weeks after implantation, exploratory celiotomy may be required to “clean out” any eggs laid internally, lash eggs, or other gross pathology.
• Owners must be warned that implantation with deslorelin is often needed for the rest of the hen’s life, as most disorders will recur after the implant wears off.
• Salpingectomy may be needed for recurrent lash egg/salpingitis.

Conclusion

Unfortunately, the most common disorders in the aging backyard hen are chronic, terminal conditions that will require lifelong treatment, care, and possibly surgery. With a dedicated owner, these hens can go on to live years, but may not if neoplasia is resistant to deslorelin. Regardless, it is important to have a conversation with the owner to determine the relationship the hen has in the family; being open and honest about prognosis, cost, and treatment options from the first visit is important.

References

1.  Crespo R, Senties-Cue G. Postmortem survey of disease conditions in backyard poultry. J Exot Pet Med. 2015;24:156–163.

2.  Leibler JH, et al. Lead exposure to children from consumption of backyard chicken eggs. Environ Res. 2018;167:445–452.

3.  Echols MS. Soft tissue surgery. In: Greenacre CB, Morishita TY, eds. Backyard Poultry Medicine and Surgery. Wiley Blackwell; 2015:220–262.

4.  Morishita T, Porter R. Gastrointestinal and hepatic diseases. In: Greenacre CB, Morishita TY, eds. Backyard Poultry Medicine and Surgery. Wiley Blackwell; 2015:181–203.

5.  Applegate TJ. Backyard poultry nutrition. In: Greenacre CB, Morishita TY, eds. Backyard Poultry Medicine and Surgery. Wiley Blackwell; 2015:72–81.

6.  Whitehead ML, Roberts V. Backyard poultry: legislation, zoonoses and disease prevention. J Small Anim Pract. 2014;55:487–496.

7.  Marmulak T, et al. FARAD Digest. Egg residue considerations during the treatment of backyard poultry. J Am Vet Med Assoc. 2015;247:1388–1395.

8.  Keller KA, et al. Long-term management of ovarian neoplasia in two cockatiels (Nymphicus hollandicus). J Avian Med Surg. 2013;27:44–52.

9.  Mans C, Pilny A. Use of GnRH-agonists for medical management of reproductive disorders in birds. Vet Clin North Am Exot Anim Pract. 2014;17:23–33.

10.  Eusemann BK, et al. Influence of a sustained release deslorelin acetate implant on reproductive physiology and associated traits in laying hens. Front Physiol. 2018;9:1–11.