Avian reproduction Flashcards
Successful reproduction requires a combination of:
External (proximate) stimuli to trigger the…
… internal (ultimate) hormonal cascade required to induce the necessary physiological reproductive response
Discuss Behavioural seasonal reproductive disorders?
–Misplaced natural ‘wild’ reproductive behaviour e.g.
–Pair bonding (often with an owner/self/inanimate object)
–Courtship regurgitation
–Cavity seeking and nest building
–Territorial aggression
Behaviour – seasonal reproductive disorders
Which leads in turn to maladjusted behaviour within the home ‘flock’ these behaviours can be?
–Aggression
–Territoriality
–Biting
–Excessive vocalisation – screaming!
–Feather plucking
–Regurgitation
–Self-mutilation
–Masturbation
»Leading to Prolapse cloaca
What is the treatment for reproductive disorders in the bird?
•Treatment
–Isolate (and remove) the “Hormone Button”
- What is initiating the hormonal cascade?
- What is flicking on the ‘proximate’ switch?
–Adjust the photo period
»Birds start to get into breeding mode when light increases – but this isn’t true for majority of birds in Britain, it isn’t the increase in light, it’s the decrease in light in autumn – just takes about 4 months to work!
–Curtail cavity seeking
–Prevent nesting stimuli
»Remove shredable material -
–Downgrade the amount and calorie (fat) level of food
–Increase exercise and foraging time (Take their mind off sex!)
»Give them something else to do!
What (if anything) is the owner doing to incite the trigger
What do we see here?
The bird – its missing feathers and toes – so chewing things! This bird has an issue and could well be that this issue is to do with unrequited love!
It’s having mating behaviour with it’s owner.
What is making the bird behave like this?
- What is initiating the hormonal cascade?
- What (if anything) is the owner doing to incite the trigger
–Stroking and petting (inducing copulation soliciting)
»Keep off the erogenous zones!! Back of the neck (a lot of nerves there) and base of the tail (if its bum comes in the air, its copulatory)
»Going to excite the bird! Then you put the bird in the cage and the bird is frustrated and this can lead to other behaviours
–Mouth to mouth feeding (inducing copulation soliciting)
–Carrying around on shoulder! (inducing bonding … etc)
»When birds are interacting, they sit side by side for eye to eye contact and they mutually groom and feed
ADJUST/MODIFY the owners approach to handling etc
How should you treat abnormal reproductive behaviour?
- Modification should be the primary approach
- Hormonal Control (Last resort in most cases)
- Synthetic GnRH antagonists (Lupron)
- Deslorelin implants
What are the reproductive problems diagnostic methods?
Bloods
•Birds (females) that are in reproductive mode tend to have:
–Increased serum proteins (mainly globulins)
–Increased TOTAL (not ionised) Ca levels
–Increased uric acid levels
–Increased cholesterol
Be aware of these when interpreting (all) bloods – especially if you are testing for something else!
(Know the sex of your patient!)
- Increased medullary bone can often be seen on X-ray
- in reproductively active female birds
Discuss chronic egg laying?
–Chronic egg laying (esp. Cockatiels, lovebirds, budgies) occurs when, without regard to the presence of a mate or accurate breeding season, a hen lays:
•Multiple clutches
–Removing the eggs as they are laid can ‘induce’ the bird to lay more – ‘double clutching’
–Pigeons lay 2 eggs, usually one of each sex
–Canaries lay 3, 4 or 5
–Chickens lay one a day
Discuss Determinate and Indeterminate layers?
- Determinate – a set number
- The amount they lay is often due to their brood patch
- Parrots are indeterminate, so if you keep removing the eggs, they often keep laying
- Large number of eggs in succession can lead to: (issues)
–Uterine inertia – Prolapse
–Calcium depletion
»Egg binding
»Yolk ceolomitis
»Osteoporosis (fractures)
Discuss Predisposing factors to chronic egg laying:
- Increased photoperiod (approximate)
- Food type availability (High fat) (prox)
- Presence of actual or perceived mates
–Toys, owners, mirrors, other birds (prox)
Chronic egg laying
–Treatment options?
Environmental changes
–Move cage*
»Why would this make any difference? Potentially differing light. It has a territory, feels settled where it is, if you move somewhere – its lost nesting site and has to keep reprograming, if you keep doing this – bird will think something has gone wrong with breeding cycle and hormone cascade changes
–72hrs continual light then decrease photoperiod (8-10 hrs) (Q: Why/how might this work?)
»It’s the decreasing daylight that makes them breed, at end of summer – birds have that much light that they become refractive and they stop – deplete whole of the GnRH and take them back to square 1 – photorefractive
–Remove all nesting material
–Rearrange the cage ‘furniture’
»Move food bowls, take mirror away, give it another toy to chew up
Behavioural modification
–Remove real/perceived mates
–Discourage territorial behaviour*
–Prevent ‘petting’
Allow?? a limited period of brooding – because of determinate and indeterminant layer, if we allow to brood – prolactin kicks in, responsible for milk production in pigeons (crop milk) and male birds get prolactin. Stimulate for prolactin is brood patch, pressure here sends signal to pit gland – so limited amount of brooding is okay
Discuss further treatment for chronic egg laying?
Diet modification (Prox)
–Important to ensure health
–Reduction of high fat foods–seeds
Pharmacological actions (Ult)
–GnRH antagonists
»Deslorelin
Surgical salpingohysterectomy
–Ovaries regress on their own – remove uterus
What can cause –Abnormal eggs – soft-shelled; abnormal shell texture; small size?
- Reproductive tract abnormalities
- Nutritional – Deficiencies Ca; Vit A; Vit D; trace mins
- Chronic oviductal pathologies
Case scenario:
7 y.o single pet hand-tame African Grey, Charlie, presented as an OOH emergency.
Main presenting symptoms: Owners came home to find Charlie on cage floor gasping; legs splayed behind it and wings out; mild tremors
What would be your DD?
–Respiratory/Cardiovascular
–Neurological (Undoubtedly but is it primary?)
- Trauma (cage injury – free-flying?)
- Toxins
–Heavy metals – Pb; Zinc; Teflon; Plant
- Hypocalcaemia
- Terminal seizures (e.g.– granuloma, TB, Asper, aBV)
–Bleed – abdomen/cerebral
•Stroke (common for birds)
–Reproductive
- Egg-binding etc.
- We have an acute problem but could be a chronic cause!
Assess you treartment priorities for this case?
–Oxygen – Air-sac tube?
–Antibiotics
–Food
–Fluid
–Pain relief
–Warmth and quiet
–Other? (Anticonvulsants?)
–Diazepam is an easy go to for parrots – anti-convulsant
You need a basic history – what questions?
- Sex of bird – is it known?
- Diet
- Previous problems
- Is the bird allowed out of the cage unsupervised?
Have the owners taken the bird anywhere recently?
What does a BCS of 4/5 look like?
What does a BCS of 3/5 look like?
What does a BCS of 5/5 look like?
What does a BCS of 2/5 look like?
What does a BCS of 1/5 look like?
Discuss –Egg retention and Egg-binding (dystocia)?
•Any bird but most common in smaller species
–Budgies, cockatiels, finches, canaries, conures
»Presenting sign generally = dead bird!! Especially in the little birds
–but also African Greys, Macaws and Amazons
Where presenting signs are:
»Early and generally without the hypocalcaemic fits
»Fluffed up (could be almost any bird illness)
»Hunched back
»Straining but intermittent and not always observed may have blood
»Lack of faeces: constipation not an issue in birds
»Off food - ????
More advanced +/- hypoCa.
»Varying degrees of the case scenario
»Prolapsed cloaca
»Dead!
Egg retention and egg binding (dystocia)
Most common causes?
–Malnutrition (deficiencies Ca, Vit A and E and obesity)
–Chronic egg laying
–Malformed eggs (oviductal disease)
–First-time layers
–Systemic disease
–Genetic predisposition
–Oviductal disease
–Lack of exercise
–Lack of hormonal preparedness
–Low temperatures (muscle relaxation)
Egg retention and egg binding (dystocia)
Why is it a problem?
An egg lodged in the pelvic canal may compress the
–pelvic blood vessels, kidneys, ureters and ischiatic nerves, causing:-
»Circulatory disorders (hence the fluids!)
»Retention of urine and faeces
»Lameness, paresis or paralysis
»Pressure necrosis of the oviductal wall may occur (if it lives long enough!)
»+ Pain and Distress
Dystocia may cause Metabolic disturbances by:
- Interfering with normal defecation and micturition, and cause ileus and renal disease, respectively
- Dehydration
Egg retention and egg binding Treatment?
Dependent on clinical presentation –
Judgement call: However…
»Should always be considered an emergency
»Stabilise before attempted egg removal -
Heat, fluids, calcium, +/- analgesia (diazepam)
»Prolapsed tissue should be lubricated and rehydrated and replaced where possible
This may be sufficient to induce oviposition – if not:
»Topical Prostaglandin E dramatically relaxes the utero-vaginal sphincter and stimulates oviductal contractions. Potentiates oxytocin
»Oxytocin (0.5iu/kg IM) repeated up to 3x @30-60m (readily available but no relaxation)
If the egg is visible through cloaca what can you do?
–Wait and see
–Milk out through cloaca
–Implode egg and wait – if can see egg but cannot move it
- Stab egg through visible area with a large gauge (21g-16g) syringe needle draw back to remove yolk and then physically implode it – if we can see it and cannot remove it, the reason its causing a problem is due to pressure.
- May then be possible to gently remove imploded shell with forceps – will have removed pressure on nerves and blood vessels. If bird not distressed, can sit back and wait
- Wait and see. 36h not unreasonable (The pressure is off!)
Any other thoughts?
Repeating Ca/oxytocin (2-4) hours; Fluids
Lubricant?
If supportive and medical treatment fail to deliver the egg what can you do?
Ovocentesis
–Use a 21g-16g syringe needle on a syringe and pierce the egg either via the cloacal opening if visible or directly through the abdominal wall.
–Aspiration of the contents will usually collapse the egg (assist with manual pressure) which should be passed ~36 hrs
–Not without risk – but not too much risk attached, more risk attached in leaving the egg there! Options limited
Look at this image of a normal and imploded egg?
Discuss Oviductal prolapse
(Can include uterus, partial vagina and cloaca, egg)?
Cause
»Excessive or chronic straining due to egg laying
»Loss of uterine tone (hypocalcaemia)
»Metritis
Treatment (+ fluids, abs, pain relief)
»Determining the viability of the prolapsed tissue is critical in prognosis and treatment options
»Keep moist and reduce swelling with 50% dextrose
»Replace and hold in place with suture (ensure bird able to defecate)
»Amputation
»Replace by abdominal surgery (Uterus)
Discuss Coelomitis – egg yolk peritonitis?
Causes
–Ectopic eggs
–Ovarian neoplasia
–Cystic ovarian disease
–Salpingitis and oviductal disease
Clinical signs
–Abdominal distension
–Dyspnoea
–Depression
–(History of prior egg laying)
Support diagnostics
–Heterophilia, hyperglobulinaemia, hypercolesterolaemia
What is going on here?
Ventrodorsal radiograph of a cockatiel hen with reproductive-associated coelomitis.
Note the severely enlarged fluid/soft tissue density, cranial displacement of the grit-filled ventriculus, obliteration/compress-ion of the caudal thoracic and abdominal air sacs, and increased density of both femurs
Coelomitis – egg yolk peritonitis what is treatment?
–Therapeutic abdominocetesis to alleviate abdominal distress and dyspnoea
–Supportive care
–Antibiosis
–Analgesics
–Hormone therapy
–Surgery
Discuss Prolapsed phalluses?
•The only birds with an intromittent phallus are
–Ratites (ostrich, emu etc), Tinamous, and Anseriformes (ducks, geese)
•Most commonly seen in Anseriformes during the breeding season
Discuss the Prolapsed phallus further?
Issues
–Necrosis due to physical trauma (being pecked!)
–Congestion leading to inability to empty cloaca
Treatment
–Reduction (generally not easy)
»Lubrication, warm water baths, + stay sutures
–For recurrent prolapse or necrotic phallus – amputation (will prevent breeding!)
»Simply done with GA, scissors and haemostasis
•
What are the reasons for Salpingohysterotomy/ectomy (C-section)?
–Egg retention
–Egg binding
–Chronic egg laying
–Egg related coelomitis
–Oviductal disease
–Ovarian cysts and tumours
–Sterilisation to prevent breeding
–Diagnostics
How is a Salpingohysterotomy (C-section) performed?
For precise surgical procedure consult relevant texts
Approach
–Left lateral or Midline can be used
–Close with 6-0, 8-0 absorbable suture with atraumatic needle, inverting continuous pattern
–Endoscopic
Consideration
–If coelomic irrigation is to be used consider open air sacs and pulmonary exposure
ALWAYS CONSIDER ALTERNATIVES -
NUTRITIONAL, BEHAVIOURAL AND HORMONAL THERAPY
When is a vasectomy or orchidectomy indicated?
Vasectomy
–Prevention of breeding
–Research
Orchidectomy
–Tumours
–Hormonally derived adverse behaviour (ethics?)
Discuss Paediatric Medicine?
- The majority of problems with young birds are related to husbandry
- Ensure these are fully investigated before looking for infectious agents
Most chicks are presented at the vets either:
As incubator hatched hand reared
–Early husbandry (brooder/incubator) induced problems
–Hand rearing related problems
Parent hatched and removed for hand rearing quite early in life
–Mainly hand rearing problems
Parent hatched and problem(s) found at weaning/leaving nest
–Parent husbandry (diet)
–Genetic
Discuss Therapeutic considerations for paediatric patients?
Do use fluids and antimicrobials in young birds
- Be aware of drugs metabolised by the liver/kidneys
- S/C injections are preferable
–Muscle trauma
–Accidentally pushing needle through keel bone
Discuss Surgical considerations in the paediatric patient?
Major concern is thermoregulation during anaesthesia
- Keep surgery time short (15mins)
- Orthopaedic procedures can possible be delayed until later
Commonly presented conditions of paediatric patient?
–Dehydration
- Brooder temperature
- Direct lack of fluids
- Osmotic effect of hand rearing food
–Unretracted yolk sac
–Stunting
- Brooder temperature
- Disease
- Genetics
- Underfeeding/Quality of hand rearing formula
–Foreign body ingestion or impaction
•Bedding substrate
–Aspiration pneumonia
–Brooder pneumonia (Aspergillosis)
Discuss leg and toe abnormalities in the paediatric patient?
Leg and toe deformities
•Metabolic bone disease (common)
–Poor nutrition of parent or hand rearing formula
–‘Plastic pot’ rearing places undue pressure on legs
–Severe cases easily diagnosed as have
»Folding fractures (tibiotarsal)
»Postural problems
–X-rays will reveal extent
–Consider quality of life and euthanasia – painful!!
–Re-fracture and pin
–If mild and bird can perch possibly leave alone
Discuss Constricted toe syndrome?
–Low brooder humidity?
–Usually need amputation – simple with scissors
Discuss Spraddle or splay leg?
–Nutritional
–Poor footing
–Genetic
–If caught early (and not a involve a genetic malformation of the stifle or hip) can be corrected by use of soft – foam hobbles and improving the footing
Discuss Beak malformations in paediactric patient?
•Trauma
–Siblings
–Self
–Parents
–During hand feeding
•Scissor beaks
–Imbalanced Calcium
–Genetic
•Mandibular prognathism (Underbite)
–Correction of the above conditions can be tried with acrylics to correct bite or more elaborate surgery
Pic shows scissor beak
Discuss Regurgitation in the peadiatric patient?
- Over feeding
- Often a consequence of crop stasis (Sour crop–often outbreaks)
Discuss crop stasis in the paediatric patient?
Primary
–Infections mainly yeasts (Candida)
»Crop wash to confirm
»LOOK AT HUSBANDRY HYGEINE feeding protocols, brooder temperature
»Treat by use of antifungals; crop acidifiers – cider vinegar; improve husbandry; Ensure crop emptying at each feed; use pre-digestive enzymes to permit thinner hand rearing formula (Avizyme)
–Crop atony due to overstretching
»Crop bra
Discuss crop burns in the paediatric patient?
Crop burns
»Diagnosed when a scab or fistula forms
»Caused by too hot food or…
»Hot ‘pockets’ due to microwave heating
»Heat lamps
»ALLOW to fistulate prior to surgery(delay at least 5 days)
»Surgery too soon will result in dehiscence of wound
»Close in 2 layers. Inverted for crop; simple for skin
»Support with antifungals, antibiotics, smaller more frequent feeds, pain relief in early part of disease
»Ensure adequate hydration
Egg retention and egg binding (dystocia) Clinical signs?
Clinical signs = FEMALE!
–Egg bound
»Depression, drooped wing, anorexia, dyspnoea, abdominal straining +/- blood from vent, broad stance, hunched back
»Leg paresis or paralysis (cf trauma) due to pressure on the ischiatic nerves; especially when hypocalcaemia present
»Egg usually palpable (confirm with x-ray, ultra sound) – Do not confuse gizzard!
»Sudden death (found dead!)
–Egg retention
»Less severe – possibly only abdominal distension
»Consider ectopic egg – x-ray
Discuss Egg retention and egg binding treatment?
If supportive and medical treatment fail to deliver the egg:-
–Manual manipulation
»‘Milking’ the egg into the pelvic canal
–Ovocentesis
»Imploding the egg to reduce pressure on the nerves and organs
»Use a 21g-16g syringe needle on a syringe and pierce the egg either via the cloacal opening if visible or directly through the abdominal wall. Aspiration of the contents will usually collapse the egg (assist with manual pressure) which should be passed ~36 hrs
– Surgery
