Exotics endocrinology Flashcards
List the common endocrinopathies of ferrets
- Hyperadrenocorticism
- Insulinoma
- Persistent oestrus
- Diabetes mellitus
- Hypothyroidism
- Phaechromocytoma
List the common endocrinopathies of guinea pigs
- Cystic ovaries
- Alopecia of pregnancy and lactation
- Diabetes mellitus
- Hyperthyroidism
- Hyperadrenocorticism
What are the most common endocrinopathies of the following species?
a: rat
b: syrian hamster
c: chinese hamster, degu and chinchilla
d: gerbil
e: rabbit
a: pituitary gland adenoma
b: hyperadrenocorticism
c: diabetes mellitus
d: cystic ovaries, diabetes mellitus, HAC
e: diabetes mellitus, adrenal gland tumours
Compare insulinomas in ferrets and dogs
Tend not to be malignant in ferrets unlike in dogs, but often recur following surgery
What are insulinomas?
Small tumours of pancreatic beta-cells that produce excess insulin resulting in hypoglycaemia
What condition is often concurrent with insulinomas in ferrets?
Hyperadrenocorticism
What has been suggested as a cause of insulinomas in ferrets?
Feeding of processed dry foods high in carbohydrate
Describe the clinical signs of insulinomas in ferrets
- Varying degrees of hindlimb weakness
- Hypersaliation and pawing at mouth (nausea, but oral obstruction is a differential)
- Collapse
- Coma
How are endocrine diseases diagnosed in exotic pets?
- Lack of specific hormone tests for many species
- Thorough clinical exam and diagnostics to rule out other causes
Outline the diagnosis of ferret insulinomas
- Blood glucose <3.4mmol/l following 4hr fast considered diagnostic if compatible clinical signs
- Insulin:glucose ratio may help but false +ves and -ves occur
- Exploratory surgery
What is the key consideration if using human glucometers on ferrets?
Give falsely low reading, up to 25% lower
Discuss the surgical treatment of ferret insulinomas
- Nodulectomy or partial pancreatotomy may give 12mo remission
- Often magnification or touch to find nodules
- Lack of ability to feel does not preclude presence
- Not all nodules on pancreas are insulinomas
- Surgery ideal, often for younger ferrets, less for older ferrets or where surgery previously failed
Describe the medical treatment of ferret insulinomas
- Feed small, frequent meals
- Prednisolone +/- diazoxide
- Often give 6-18 months control
Identify the common disorders of calcium metabolism in birds
- Vit D3 deficiency from diet or lack of UV-B
- Egg laying leading to hypocalcaemia
- Medullary hyperostosis in laying female
- Hypocalcaemia
- Hypercalcaemia
Explain the role of UV-B in vit D3 deficiency in birds
- UV-B acts on vit precursors in cutaneous tissues and preen gland to obtain vit D3
- Often lack UV-B as windows filter this out
- Requirement for UV-B is species dependent
Outline the role of medullary bone in the production of eggs
- 30-40% of calcium for eggs from medullary bone
- Some birds prepare for laying by storing additional calcium in bones
Describe medullary hyperostosis
- Occurs in laying female ~6 weeks before laying of eggs
- lay down additional calcium to use later
- Under influence of oestrogen and vit D
- Can be normal or abnormal
Give causes of abnormal medullary hyperostosis in birds
- Cyst on ovary
- Lack of egg production
- male budgies with testicular tumours
List the potential causes of hypocalcaemia in birds
- Seed based diet
- Carnivorous diet
- Insectivorous diet
- UV-B deficiency in some birds
- Multiple clutching
Explain how a seed based diet can lead to hypocalcaemia in birds
Seed based diets deficient in calcium and vit D3, contain excessive phosphorous
Explain how a carnivorous diet can lead to hypocalcaemia in birds and reptiles
Neonatal prey or too large prey results in inverse Ca:P ratio
Explain how an insectivorous diet can lead to hypocalcaemia in birds and reptiles
Captive farmed insects, or incorrect insects for the species, may have an inverse Ca:P ratio
Explain how multiple clutching can lead to hypocalcaemia in birds
- Remove each clutch after laying, hens lay another clutch
- Get progressive decrease in quality of eggs, and hen will become deficient
- May cause bone disease in offspring
Describe the clinical signs of hypocalcaemia in adult birds
- Lethargy
- Ataxia
- Seizures
- Diarrhoea
Describe the clinical signs of hypocalcaemia in breeding females
- Egg binding
- Soft-shelled eggs
- Infertility
- Osteomalacia
Describe the clinical signs of hypocalcaemia in growing birds
Skeletal abnormalities and/or fracture (osteodystrophy)
Describe a dermatological sign that may occur in birds of all ages as a consequence of hypocalcaemia
Feather picking due to bone and joint pain
Describe the treatment of hypocalcaemic seizures in birds
- Calcium gluconate 10% IM or slow iv
- Diazepam
- Isoflurane anaesthesia to control seizures and facilitate diagnostic procedures such as blood sampling
Describe the treatment of fractures in birds
- Cage rest, analgesia, splint in some cases
- Fixation with implants usually contraindicated due to fragility of bones
- Provide padded floors and lowered perches
List the causes of hypercalcaemia in birds
- Increased oestrogen levels
- production of calcium binding proteins in reproducing females
- Hypervitaminiosis D and excessive dietary calcium intake
What are the potential outcomes of pathological hypercalcaemia in birds?
- Soft tissue mineralisation
- Nephrocalcinosis
- Visceral and articular gout
Outline the diagnosis of hypocalcaemia in birds
- History (diet, access to UV-B, egg laying)
- total and ionised calcium, albumin, ALKP
- Whole body radiographs
- Serum PTH and vit D3 analysis
- Bone and eggshell analysis in some cases
Evaluate the significance of radiographs in the diagnosis of hypocalcaemia in birds
- Normal radiograph does not mean normal calcium
- Need to lose 30% calcium from bone to show radiographic changes
Describe how vit D3 is obtained by reptiles
- Some from diet, but not enough for many
- Main source is by action of UV-B on precursors in cutaneous tissue, essential for proper calcium metabolism in these species
Explain the importance of temperature in vit D3 synthesis
Reaction is temperature dependent, suboptimal will result in inadequate vit D3 synthesis and subsequent deficiency. Light and heat source need to be together
Compare the calcium metabolism at egg laying in birds and reptiles
Similar, other than that medullary hyperostosis does not occur in reptiles
Explain what is unusual about calcium storage in geckos
- Many gecko species have endolymphatic calcium sacs in pharynx
- More pronounced in reproductively active females
Explain how herbivorous diets may lead to hypocalcaemia in reptiles
- Often have inverse Ca:P ratio
- Or contain phytates and oxalates which may further reduce calcium availability in the diet
What is the most common endocrine condition in captive reptiles?
NSHP - nutritional secondary hyperparathyroidism
What conditions are associated with hypocalcaemia in reptiles
- Nutritional secondary hyperparathyroidism
- Renal secondary hyperparathyroidism
Describe the clinical signs of hypocalcaemia in reptiles
- Muscle tremor, fasciculations, toe twitching
- Abnormal gait, weakness, dysecdysis
- Constipation, egg binding, cloacal organ prolapse
- Tongue dysfunction in chameleons
- Skeletal deformity and pathological fractures
Describe the diagnosis of hypocalcaemia in reptiles
- History: diet, UV-B, egg laying
- Total and ionised calcium, albumin and ALKP
- Whole body radiographs (2)
- (Vit D3 analysis)
Describe the treatment of hypocalcaemia in reptiles
- Provide access to appropriate UV-B lamp with access to unfiltered sunshine whenever possible
- Convert to an appropriate supplemented diet
- Consider ovariosalpynghysterectomy once stable esp. in prolific egg layers e.g. bearded dragon, yeme chameleon
- Clacium gluconate 10% IM
- Calcium glubionate/lactobionate PO
Describe the treatment of hypocalcaemic bone disease in reptiles
- Cage rest, analgesia (tramadol, meloxicam), splints
- Fixation with implants contraindicated
- May require euthanasia
List the causes of hypercalcaemia in reptiles
- Increased oestrogen levels and production of calcium-binding proteins in reproducing females
- Hypervitaminosis D
- Excessive dietary calcium
- Primary hyperparathyroidism
- Osteolytic bone lesions
What are the potential consequences of pathological hypercalcaemia in reptiles?
- Soft tissue mineralisation
- Nephrocalcinosis
- Visceral and articular gout
How does the calcium metabolism of rabbits differ to that of most other mammals?
- Rabbits passively absorb majority of ingested calcium in gut independently of vitamin D
- Excrete excess calcium
What may hypercalcaemia be indicative of in rabbits?
Renal disease (reduced excretion)
What may happen to the urine in rabbits with excessive dietary calcium and/or complexes with inflammatory proteins?
Urine “sludge” and uroliths may develop
What conditions predispose rabbits for the formation of urine “sludge”
- Urinary tract stasis due to urinary tract obstruction
- Pain
- Degenerative joint disease
- Obesity
- Confinement
What may cause hypocalcaemia in rabbits?
- Altered Ca:Phos ratio
- Calcium deficient diet
Describe the consequences of hypocalcaemia in rabbits
- Demineralisation of the skull, teeth and skeleton, lumbar vertebrae first
- Spine fractures and dental disease common
- PTH increases RBC osmotic fragility causing anaemia
In what normal period may hypocalcaemia be seen in the rabbit?
In the periparturient period
List potential causes of hypercalcaemia in rabbits
- Increased dietary intake
- Renal disease
- Primary hyperparathyroidism
- Hypervitaminosis D
- Osteomyelitis
- Paraneoplastic syndrome e.g. thymoma
Describe the potential outcomes of hypercalcaemia in rabbits
- Persistently raised calcium may result in dystrophic calcification, particularly in aorta and kidneys
- Hypermineralisation of skeleton may also occur
Describe the common history for a hypercalcaemic rabbit
- Losing weight
- Painful
- Lethargic
Compare the radiographic bone density of cats and rabbits
Rabbits have normally lower bone density than a cat (therefore need to compare to rabbit radiographs to identify excessive calcification of bones in rabbits)
Describe the pathophysiology of nutritional secondary hyperparathyroidism in exotic pets
- Decreased calcium leads to increased PTH, PTH gland hyperplasia
- Increased PTH increases calcium mobilisation from bone leading to demineralisation of bone, replaced with fibrous connective tissue
Describe the biochemistry and haematology abnormalities that may be noted as a result of nutritional secondary hyperparathyroidism in exotic pets
- Total ionised calcium low or normal
- Serum alkaline phosphatase often raised
- Exception: adults, esp. African Greys presenting with hypocalcaemia may have normal skeleton and normal serum ALKP
Provide an explanation for the presentation of secondary hyperparathyroidism in adult african grey parrots
- Hypocalcaemia, normal skeleton, normal serum ALKP
- Low calcium and vit D in diet resulting gin reduced bone mobilisation and osteoclast dysfunction
Outline the treatment for nutritional secondary hyperparathyroidism in exotic species
- Convert to appropriate diet for species
- Use Ca/Vit D supplement if unable
- Provide access to unfiltered sunshine and/or avian UV-B lamp
_ educe reproductive drive
How can reproductive drive be reduced in birds?
- Shorten day length
- Remove nest sites
- Remove mates (may be the owner)
- Improve diet
- +/- pharmacological intervention
