Pituitary Tumours

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jorats

Loving rats since 2002.
Joined
Jul 20, 2007
Messages
45,196
Location
Northeastern Ontario
Pituitary adenomas are very common in rats. It seems to affect them at any age whereas it used to be only seen in older rats.

My vet has done tons of research and post mortems with PTs and has come to the conclusion that there are at least three types or three occurrences.
1. Your typical pituitary tumour growth where as the usual symptoms of confusion, loss of rear end mobility, head tilt, knuckling, loss of sense of smell are a slow progression and can take several months for it to become fatal.
2. A bleeding pituitary tumour. The symptoms are sudden and leads to a quick death.
3. A pituitary tumour that presses against a vein on top of the gland. When this occurs, it usually causes a stroke in rats. Symptoms, loss of complete mobility or one sided, fetal postion in rats, loss of appetite usually occurs but some rats can and do recover from the stroke but don't recover 100% because they still have that pituitary tumour growth. The rat can have several strokes before finally succumbing to the tumour.

Dex/prednison/prednisolone works in some cases, it can help with just the pituitary tumour and also the strokes but not in a bleeding tumour.
It reduces the swelling in the brain to the point where the rat is given some quality of life before the tumour grows too big.
My vet has seen cases where the tumour has squished the brain like a pancake. In these cases the symptoms were severe: circling, complete loss of awareness and massive porphyrin.

In each case, I would say it's important to catch it early and to administer Dex or pred as soon as possible to give your rat a fighting chance and more good times with you before the inevitable end.

I'm not a vet but this is based on our discussions with my exotic vet.
If you suspect a PT in your rat the best course of action is seeing your vet and discussing the options with them.
 
Great to have this info on a sticky! I wish that I had been thinking PT earlier with my favourite ratty girl, who died in October. For the longest time her only symptom was slight occasional clumsiness. I noticed it right away, because she had always been active and very agile. The vet found nothing wrong with her, but we were looking for problems with joints, muscles or tendons.

A couple of months later some more typical symptoms appeared. She couldn't hold or eat solid food. She suddenly developed respiratory distress and had to be pts.

Now I have an eagle eye out for any sort of change in the girls. If I'd thought to try Pred earlier I'd have had my sweetie for a while longer.
 
I had a rat that seemed to be suffering from myco, went into respiratory distress then gasping. The post mortem showed clear healthy lungs but a huge PT.
 
Look into treating your rat that has been diagnosed with a pituitary tumor with Bromocriptine or Cabergoline. These medications work against prolactin-producing pituitary tumors to stop growth and shrink the tumor, sometimes to nonexistence. Melatonin is supposed to work in the same way and is considerably cheaper for those of you who cannot afford the others or whose vets are not interested.
 
Sure thing. It made signifcant improvements in Peanut even though her tumor was so far along when we started the Cabergoline. I think it's something that should be looked into more often! My vet did the research to find out dosages, etc. I'm going in tomorrow, so I'll see if she can email me the information she found and used.
 
Here's a very interesting study using Cabergoline to treat the PT.

Case Description—A 0.65-kg (1.43-lb) 24-month-old sexually intact male albino pet rat was examined because of a 3-week history of hypodipsia, apparent blindness, and sudden change in behavior.
Clinical Findings—The rat was able to move around its cage but appeared unaware of its surroundings, was visually unresponsive, and seemed unusually aggressive. The rat’s hind limbs appeared mildly paretic, and it had sporadic difficulty placing its hind limbs on a flat surface. Given the rat’s age, history, and physical examination findings, the primary differential diagnosis was a pituitary tumor. Magnetic resonance imaging (MRI) of the rat’s brain was performed and revealed a large pituitary mass, which was indicative of a tumor.
Treatment and Outcome—Cabergoline (0.6 mg/kg [0.27 mg/lb], PO, q 72 h) was administered. On follow-up MRI 2 months later, the pituitary mass had substantially decreased in size. For 6 months following the second MRI study, the rat continued to receive the same dosage of caber- goline and had no clinical signs of disease or unusual behavior. However, at 8.5 months after the start of the treatment, the rat was in poor condition and had clinical signs similar to those initially. A third MRI study was performed and revealed substantial regrowth of the mass.The rat was eutha- nized and a necropsy was performed; a histopathologic diagnosis of pituitary adenoma was made.
Clinical Relevance—Pituitary adenomas have long been recognized as a common finding in geriatric rats (> 18 months old). Affected rats may respond favorably to oral administration of cabergoline. (J Am Vet Med Assoc 2011;239:656–660)
For the rat of this report, cabergoline was adminis- tered in preference to bromocriptine for several reasons. The dosing interval of cabergoline at every 72 hours, compared with every 24 hours for bromocriptine, is es- tablished and minimally stressful for the animal.29,30 Ca- bergoline was compounded at a concentration of 2 mg/ mL, so the rat received 0.2 mL of cabergoline suspen- sion every 72 hours, a dosing regimen likely to achieve higher client compliance than a more frequently dosed drug. According to the compounding pharmacy,c and in accordance with manufacturer’s instructions, a suspen- sion of cabergoline diphosphate is stable at room tem- perature (approx 25°C). Furthermore, banana-apple flavoring of the suspension was chosen because it was pH neutral. In contrast, a suspension of bromocriptine mesylate must be refrigerated, and consequently, shelf life and stability of bromocriptine mesylate suspension were a concern. To avoid this problem, bromocriptine is typically administered SC to animals in research studies.30 Cabergoline also offers considerable advan- tages over bromocriptine in terms of drug efficacy.31 In humans, the decrease in prolactin secretion was sig- nificantly greater with cabergoline treatment than with bromocriptine treatment (93% decrease vs 87.5% de- crease, respectively) and normalization of blood pro- lactin concentrations was greater with cabergoline than with bromocriptine.32 Approximately 24% and 11% of human patients are resistant to treatment with bro- mocriptine and cabergoline, respectively.33
Because of the limited remaining treatment op- tions, advanced age, and eventual poor condition of the rat of this report, it was ultimately euthanized. How- ever, this is the first reported case of the use of cabergo- line to treat successfully an in vivo–documented pitu- itary adenoma in a pet rat. Magnetic resonance imaging proved to be the diagnostic imaging modality of choice to detect the pituitary adenoma. Cabergoline adminis- tered at a dosage of 0.6 mg/kg PO every 72 hours was safe and temporarily effective in controlling the clinical signs associated with pituitary macroadenomas in rats.

I've got the full study is anyone wants it.

 
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